PRLD

SEC source: 0001209191-21-029033 · doc4.xml · nonDerivative · entry 1

Mauro David J · CIK 0001621172 · Chief Medical Officer

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 25,000

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

SEC source: 0001209191-21-027874 · doc4.xml · derivative · entry 4

Mauro David J · CIK 0001621172 · Chief Medical Officer

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 252,610

Underlying: Common Stock · 25,000 shares

Expires 2029-06-16

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F4 · derivative.exercise_date: The stock option vested as to 25% of the total shares monthly on May 1, 2020, and thereafter vests as to 1/48 of the total shares monthly until fully vested, subject to the Reporting Person's provision of service to the Issuer on the vesting date.

SEC source: 0001209191-21-027874 · doc4.xml · nonDerivative · entry 3

Mauro David J · CIK 0001621172 · Chief Medical Officer

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 0

F1 · kind: The transactions reported on this Form 4 were effected pursuant to a Rule 10b5-1 trading plan adopted by the reporting person.

F3 · price: The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $31.19 to $31.51, inclusive. The reporting person undertakes to provide to the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the ranges set forth herein.

SEC source: 0001209191-21-027874 · doc4.xml · nonDerivative · entry 2

Mauro David J · CIK 0001621172 · Chief Medical Officer

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 4,000

F1 · kind: The transactions reported on this Form 4 were effected pursuant to a Rule 10b5-1 trading plan adopted by the reporting person.

F2 · price: The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $30.19 to $31.18, inclusive. The reporting person undertakes to provide to the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the ranges set forth herein.

SEC source: 0001209191-21-027874 · doc4.xml · nonDerivative · entry 1

Mauro David J · CIK 0001621172 · Chief Medical Officer

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 25,000

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

SEC source: 0001209191-21-026872 · doc4.xml · derivative · entry 6

Mauro David J · CIK 0001621172 · Chief Medical Officer

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 277,610

Underlying: Common Stock · 9,617 shares

Expires 2029-06-16

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F6 · derivative.exercise_date: The stock option vested as to 25% of the total shares monthly beginning on May 1, 2020, and thereafter vests as to 1/48 of the total shares monthly until fully vested, subject to the Reporting Person's provision of service to the Issuer on the vesting date.

SEC source: 0001209191-21-026872 · doc4.xml · nonDerivative · entry 5

Mauro David J · CIK 0001621172 · Chief Medical Officer

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 0

F1 · kind: The transactions reported on this Form 4 were effected pursuant to a Rule 10b5-1 trading plan adopted by the reporting person.

F5 · price: The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $39.38 to $40.05, inclusive. The reporting person undertakes to provide to the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the ranges set forth herein.

SEC source: 0001209191-21-026872 · doc4.xml · nonDerivative · entry 4

Mauro David J · CIK 0001621172 · Chief Medical Officer

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 3,549

F1 · kind: The transactions reported on this Form 4 were effected pursuant to a Rule 10b5-1 trading plan adopted by the reporting person.

F4 · price: The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $38.38 to $39.37, inclusive. The reporting person undertakes to provide to the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the ranges set forth herein.

SEC source: 0001209191-21-026872 · doc4.xml · nonDerivative · entry 3

Mauro David J · CIK 0001621172 · Chief Medical Officer

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 4,842

F1 · kind: The transactions reported on this Form 4 were effected pursuant to a Rule 10b5-1 trading plan adopted by the reporting person.

F3 · price: The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $37.38 to $38.36, inclusive. The reporting person undertakes to provide to the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the ranges set forth herein.

SEC source: 0001209191-21-026872 · doc4.xml · nonDerivative · entry 2

Mauro David J · CIK 0001621172 · Chief Medical Officer

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 6,343

F1 · kind: The transactions reported on this Form 4 were effected pursuant to a Rule 10b5-1 trading plan adopted by the reporting person.

F2 · price: The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $36.37 to $37.35, inclusive. The reporting person undertakes to provide to the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the ranges set forth herein.

SEC source: 0001209191-21-026872 · doc4.xml · nonDerivative · entry 1

Mauro David J · CIK 0001621172 · Chief Medical Officer

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 9,617

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

SEC source: 0001209191-21-026875 · doc4.xml · derivative · entry 6

Scherle Peggy · CIK 0001824632 · Chief Scientific Officer

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 66,460

Underlying: Common Stock · 4,630 shares

Expires 2028-11-12

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F7 · derivative.exercise_date: The stock option vested as to 25% of the total shares monthly beginning on November 13, 2019, and thereafter vests as to 1/48 of the total shares monthly until fully vested, subject to the Reporting Person's provision of service to the Issuer on the vesting date.

SEC source: 0001209191-21-026875 · doc4.xml · nonDerivative · entry 5

Scherle Peggy · CIK 0001824632 · Chief Scientific Officer

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 172,920

F2 · kind: The transactions reported on this Form 4 were effected pursuant to a Rule 10b5-1 trading plan adopted by the reporting person.

F6 · price: The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $39.39 to $40.05, inclusive. The reporting person undertakes to provide to the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the ranges set forth herein.

F1 · balance_after: Certain of the shares are subject to forfeiture to the Issuer if underlying vesting conditions are not met.

SEC source: 0001209191-21-026875 · doc4.xml · nonDerivative · entry 4

Scherle Peggy · CIK 0001824632 · Chief Scientific Officer

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 174,589

F2 · kind: The transactions reported on this Form 4 were effected pursuant to a Rule 10b5-1 trading plan adopted by the reporting person.

F5 · price: The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $38.38 to $39.36, inclusive. The reporting person undertakes to provide to the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the ranges set forth herein.

F1 · balance_after: Certain of the shares are subject to forfeiture to the Issuer if underlying vesting conditions are not met.

SEC source: 0001209191-21-026875 · doc4.xml · nonDerivative · entry 3

Scherle Peggy · CIK 0001824632 · Chief Scientific Officer

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 175,258

F2 · kind: The transactions reported on this Form 4 were effected pursuant to a Rule 10b5-1 trading plan adopted by the reporting person.

F4 · price: The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $37.38 to $38.32, inclusive. The reporting person undertakes to provide to the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the ranges set forth herein.

F1 · balance_after: Certain of the shares are subject to forfeiture to the Issuer if underlying vesting conditions are not met.

SEC source: 0001209191-21-026875 · doc4.xml · nonDerivative · entry 2

Scherle Peggy · CIK 0001824632 · Chief Scientific Officer

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 176,133

F2 · kind: The transactions reported on this Form 4 were effected pursuant to a Rule 10b5-1 trading plan adopted by the reporting person.

F3 · price: The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $36.37 to $37.27, inclusive. The reporting person undertakes to provide to the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the ranges set forth herein.

F1 · balance_after: Certain of the shares are subject to forfeiture to the Issuer if underlying vesting conditions are not met.

SEC source: 0001209191-21-026875 · doc4.xml · nonDerivative · entry 1

Scherle Peggy · CIK 0001824632 · Chief Scientific Officer

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 177,550

F1 · balance_after: Certain of the shares are subject to forfeiture to the Issuer if underlying vesting conditions are not met.

SEC source: 0001209191-21-026874 · doc4.xml · derivative · entry 3

Pierce Christopher · CIK 0001824631 · EVP and Chief of Business Oper

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 7,618

Underlying: Common Stock · 200 shares

Expires 2030-03-26

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F2 · derivative.exercise_date: The stock option is fully vested.

SEC source: 0001209191-21-026874 · doc4.xml · nonDerivative · entry 2

Pierce Christopher · CIK 0001824631 · EVP and Chief of Business Oper

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 3,750

F1 · kind: The transactions reported on this Form 4 were effected pursuant to a Rule 10b5-1 trading plan adopted by the reporting person.

SEC source: 0001209191-21-026874 · doc4.xml · nonDerivative · entry 1

Pierce Christopher · CIK 0001824631 · EVP and Chief of Business Oper

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 3,950

SEC source: 0001209191-21-026873 · doc4.xml · derivative · entry 3

Morosini Deborah · CIK 0001824625 · EVP, Chief of Clinical Affairs

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 7,546

Underlying: Common Stock · 100 shares

Expires 2030-03-26

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F2 · derivative.exercise_date: The stock option is fully vested.

SEC source: 0001209191-21-026873 · doc4.xml · nonDerivative · entry 2

Morosini Deborah · CIK 0001824625 · EVP, Chief of Clinical Affairs

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 444

F1 · kind: The transactions reported on this Form 4 were effected pursuant to a Rule 10b5-1 trading plan adopted by the reporting person.

SEC source: 0001209191-21-026873 · doc4.xml · nonDerivative · entry 1

Morosini Deborah · CIK 0001824625 · EVP, Chief of Clinical Affairs

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 544

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

SEC source: 0001209191-21-026291 · doc4.xml · derivative · entry 4

Mauro David J · CIK 0001621172 · Chief Medical Officer

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 287,227

Underlying: Common Stock · 15,383 shares

Expires 2029-06-16

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F4 · derivative.exercise_date: The stock option vested as to 25% of the total shares monthly beginning on May 1, 2020, and thereafter vests as to 1/48 of the total shares monthly until fully vested, subject to the Reporting Person's provision of service to the Issuer on the vesting date.

SEC source: 0001209191-21-026291 · doc4.xml · nonDerivative · entry 3

Mauro David J · CIK 0001621172 · Chief Medical Officer

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 0

F1 · kind: The transactions reported on this Form 4 were effected pursuant to a Rule 10b5-1 trading plan adopted by the reporting person.

F3 · price: The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $39.30 to $40.25, inclusive. The reporting person undertakes to provide to the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the ranges set forth herein.

SEC source: 0001209191-21-026291 · doc4.xml · nonDerivative · entry 2

Mauro David J · CIK 0001621172 · Chief Medical Officer

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 7,083

F1 · kind: The transactions reported on this Form 4 were effected pursuant to a Rule 10b5-1 trading plan adopted by the reporting person.

F2 · price: The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $38.30 to $39.28, inclusive. The reporting person undertakes to provide to the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the ranges set forth herein.

SEC source: 0001209191-21-026291 · doc4.xml · nonDerivative · entry 1

Mauro David J · CIK 0001621172 · Chief Medical Officer

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 15,383

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

SEC source: 0001209191-21-026294 · doc4.xml · derivative · entry 5

Scherle Peggy · CIK 0001824632 · Chief Scientific Officer

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 71,090

Underlying: Common Stock · 15,370 shares

Expires 2028-11-12

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F5 · derivative.exercise_date: The stock option vested as to 25% of the total shares monthly beginning on November 13, 2019, and thereafter vests as to 1/48 of the total shares monthly until fully vested, subject to the Reporting Person's provision of service to the Issuer on the vesting date.

SEC source: 0001209191-21-026294 · doc4.xml · nonDerivative · entry 4

Scherle Peggy · CIK 0001824632 · Chief Scientific Officer

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 172,920

F2 · kind: The transactions reported on this Form 4 were effected pursuant to a Rule 10b5-1 trading plan adopted by the reporting person.

F1 · balance_after: Certain of the shares are subject to forfeiture to the Issuer if underlying vesting conditions are not met.

SEC source: 0001209191-21-026294 · doc4.xml · nonDerivative · entry 3

Scherle Peggy · CIK 0001824632 · Chief Scientific Officer

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 173,120

F2 · kind: The transactions reported on this Form 4 were effected pursuant to a Rule 10b5-1 trading plan adopted by the reporting person.

F4 · price: The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $39.26 to $40.15, inclusive. The reporting person undertakes to provide to the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the ranges set forth herein.

F1 · balance_after: Certain of the shares are subject to forfeiture to the Issuer if underlying vesting conditions are not met.

SEC source: 0001209191-21-026294 · doc4.xml · nonDerivative · entry 2

Scherle Peggy · CIK 0001824632 · Chief Scientific Officer

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 180,001

F2 · kind: The transactions reported on this Form 4 were effected pursuant to a Rule 10b5-1 trading plan adopted by the reporting person.

F3 · price: The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $38.26 to $39.25, inclusive. The reporting person undertakes to provide to the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the ranges set forth herein.

F1 · balance_after: Certain of the shares are subject to forfeiture to the Issuer if underlying vesting conditions are not met.

SEC source: 0001209191-21-026294 · doc4.xml · nonDerivative · entry 1

Scherle Peggy · CIK 0001824632 · Chief Scientific Officer

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 188,290

F1 · balance_after: Certain of the shares are subject to forfeiture to the Issuer if underlying vesting conditions are not met.

SEC source: 0001209191-21-026292 · doc4.xml · derivative · entry 3

Morosini Deborah · CIK 0001824625 · EVP, Chief of Clinical Affairs

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 7,646

Underlying: Common Stock · 1,000 shares

Expires 2030-03-26

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F3 · derivative.exercise_date: The stock option is fully vested.

SEC source: 0001209191-21-026292 · doc4.xml · nonDerivative · entry 2

Morosini Deborah · CIK 0001824625 · EVP, Chief of Clinical Affairs

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 444

F1 · kind: The transactions reported on this Form 4 were effected pursuant to a Rule 10b5-1 trading plan adopted by the reporting person.

F2 · price: The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $40.00 to $40.15, inclusive. The reporting person undertakes to provide to the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the ranges set forth herein.

SEC source: 0001209191-21-026292 · doc4.xml · nonDerivative · entry 1

Morosini Deborah · CIK 0001824625 · EVP, Chief of Clinical Affairs

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 1,444

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

SEC source: 0001209191-21-026293 · doc4.xml · derivative · entry 3

Pierce Christopher · CIK 0001824631 · EVP and Chief of Business Oper

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 7,818

Underlying: Common Stock · 828 shares

Expires 2030-03-26

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F3 · derivative.exercise_date: The stock option is fully vested.

SEC source: 0001209191-21-026293 · doc4.xml · nonDerivative · entry 2

Pierce Christopher · CIK 0001824631 · EVP and Chief of Business Oper

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 3,750

F1 · kind: The transactions reported on this Form 4 were effected pursuant to a Rule 10b5-1 trading plan adopted by the reporting person.

F2 · price: The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $40.00 to $40.30, inclusive. The reporting person undertakes to provide to the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the ranges set forth herein.

SEC source: 0001209191-21-026293 · doc4.xml · nonDerivative · entry 1

Pierce Christopher · CIK 0001824631 · EVP and Chief of Business Oper

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 4,578

SEC source: 0001638599-21-000113 · doc4_7019.xml · derivative · entry 4

BAKER BROS. ADVISORS LP · CIK 0001263508 · Director · 10% owner

667, L.P. · CIK 0001551139 · Director · 10% owner

Baker Bros. Advisors (GP) LLC · CIK 0001580575 · Director · 10% owner

Baker Brothers Life Sciences LP · CIK 0001363364 · Director · 10% owner

BAKER FELIX · CIK 0001087940 · Director · 10% owner

BAKER JULIAN · CIK 0001087939 · Director · 10% owner

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: Not disclosed

Ownership: Indirect · See Footnotes

Disclosed balance after: 41,500

Underlying: Common Stock · 5,188 shares

Expires 2030-09-01

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F10 · price: These non-qualified stock options are not priced.

F1 · derivative.exercise_date: Common stock ("Common Stock") of Prelude Therapeutics Incorporated (the "Issuer") received upon exercise of 5,188 non-qualified stock options exercisable into Common Stock on a 1-for-1 basis ("Stock Options") that were issued to Dr. Kelvin M. Neu, a former employee of Baker Bros. Advisors LP (the "Adviser") and former director of the board of directors of the Issuer (the "Board"), in his capacity as a former director of the Issuer are reflected in the ownership of each of the Funds (as defined below). The Stock Options with a strike price of $12.85 per share, vested in 36 equal monthly installments beginning on October 24, 2020, subject to an individual designated by the Adviser continuing to serve on the Board.

F2 · derivative.exercise_date: Dr. Neu and Julian C. Baker, a managing member of Baker Bros. Advisors (GP) LLC (the "Adviser GP") and current director of the Issuer pursuant to the policies of the Adviser, do not have any right to the pecuniary interest in the Stock Options issued or the Common Stock received upon exercise of such Stock Options for either Dr. Neu's past service on the the Board or Julian C. Baker's current service on the Board Each of the Funds owns an indirect proportionate pecuniary interest in the Common Stock received upon exercise of the Stock Options issued in connection with Dr. Neu's past service on the Board and Julian C. Baker's current service on the Board, less the exercise cost of those options.

F4 · ownership.nature: In addition, each of the Funds has the right to receive a portion of the 41,500 options reported in column 9 of Table II held directly by Dr. Neu.

F5 · ownership.nature: After giving effect to the transaction reported herein and as a result of their ownership interest in (i) Baker Brothers Life Sciences Capital, L.P. and (ii) Baker Brothers Life Sciences, L.P. ("Life Sciences", and together with 667, the "Funds"), Julian C. Baker and Felix J. Baker each may be deemed to have an indirect pecuniary interest in 9,247,763 shares of Common Stock reported in column 5 of Table I directly held by Life Sciences, a limited partnership of which the sole general partner is Baker Brothers Life Sciences Capital, L.P., a limited partnership of which the sole general partner is Baker Brothers Life Sciences Capital (GP),LLC, due to their interest in Life Sciences and Baker Brothers Life Sciences Capital, L.P.'s right to receive an allocation of a portion of the profits from Life Sciences and the 5,188 shares of Common Stock reported in column 5 of Table I held directly by the Adviser.

F6 · ownership.nature: The Adviser serves as the investment adviser to the Funds. In connection with the services provided by the Adviser, the Adviser receives an asset-based management fee that does not confer any pecuniary interest in the securities held by the Funds. The Adviser GP is the Adviser's sole general partner. Julian C. Baker and Felix J. Baker are managing members of the Adviser GP. The Adviser has complete and unlimited discretion and authority with respect to the investment and voting power of the securities held by the Funds. The general partners of the Funds relinquished to the Adviser all discretion and authority with respect to the investment and voting power of the securities held by the Funds.

F7 · ownership.nature: Julian C. Baker, Felix J. Baker, the Adviser GP and the Adviser disclaim beneficial ownership of the securities held directly by the Funds except to the extent of their pecuniary interest therein, and this report shall not be deemed an admission that any of Julian C. Baker, Felix J. Baker, the Adviser GP or the Adviser is a beneficial owner of such securities for purposes of Section 16 or any other purpose.

F8 · ownership.nature: The policy of the Funds and the Adviser, and the Nominee Agreement (as defined below) do not permit former employees of the Adviser or managing members of the Adviser GP to receive compensation for serving as a director of the Issuer, and the Funds are instead entitled to the pecuniary interest in the Common Stock received from the exercise of the Stock Options.

F9 · ownership.nature: Solely as a result of their ownership interest in (i) the general partners of the Funds and (ii) the Funds as limited partners, Felix J. Baker and Julian C. Baker may be deemed to have an indirect pecuniary interest in the shares issued upon exercise of the Stock Options (i.e. no direct pecuniary interest).

F11 · ownership.nature: The disclosure of the exercise of Stock Options for Common Stock reported on this form is a single exercise of 5,188 shares. The 5,188 shares are reported for each of the Funds as each has an indirect pecuniary interest.

F12 · ownership.nature: Dr. Neu entered into a Nominee Agreement (the "Nominee Agreement") with the Adviser on January 23, 2021. Pursuant to the Nominee Agreement, Dr. Neu agreed that, with respect to the Stock Options and Common Stock from the exercise of Stock Options, the Adviser will have dispositive power as well as the ability to control the timing of exercise of the Stock Options and that any proceeds from the sale of the Common Stock will be remitted to the Adviser net of brokerage commissions consistent with the policies of the Adviser for current employees.

SEC source: 0001638599-21-000113 · doc4_7019.xml · derivative · entry 3

BAKER BROS. ADVISORS LP · CIK 0001263508 · Director · 10% owner

667, L.P. · CIK 0001551139 · Director · 10% owner

Baker Bros. Advisors (GP) LLC · CIK 0001580575 · Director · 10% owner

Baker Brothers Life Sciences LP · CIK 0001363364 · Director · 10% owner

BAKER FELIX · CIK 0001087940 · Director · 10% owner

BAKER JULIAN · CIK 0001087939 · Director · 10% owner

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: Not disclosed

Ownership: Indirect · See Footnotes

Disclosed balance after: 41,500

Underlying: Common Stock · 5,188 shares

Expires 2030-09-01

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F10 · price: These non-qualified stock options are not priced.

F1 · derivative.exercise_date: Common stock ("Common Stock") of Prelude Therapeutics Incorporated (the "Issuer") received upon exercise of 5,188 non-qualified stock options exercisable into Common Stock on a 1-for-1 basis ("Stock Options") that were issued to Dr. Kelvin M. Neu, a former employee of Baker Bros. Advisors LP (the "Adviser") and former director of the board of directors of the Issuer (the "Board"), in his capacity as a former director of the Issuer are reflected in the ownership of each of the Funds (as defined below). The Stock Options with a strike price of $12.85 per share, vested in 36 equal monthly installments beginning on October 24, 2020, subject to an individual designated by the Adviser continuing to serve on the Board.

F2 · derivative.exercise_date: Dr. Neu and Julian C. Baker, a managing member of Baker Bros. Advisors (GP) LLC (the "Adviser GP") and current director of the Issuer pursuant to the policies of the Adviser, do not have any right to the pecuniary interest in the Stock Options issued or the Common Stock received upon exercise of such Stock Options for either Dr. Neu's past service on the the Board or Julian C. Baker's current service on the Board Each of the Funds owns an indirect proportionate pecuniary interest in the Common Stock received upon exercise of the Stock Options issued in connection with Dr. Neu's past service on the Board and Julian C. Baker's current service on the Board, less the exercise cost of those options.

F3 · ownership.nature: After giving effect to the transaction reported herein and as a result of their ownership interest in (i) Baker Biotech Capital, L.P. and (ii) 667, L.P. ("667"), Julian C. Baker and Felix J. Baker each may be deemed to have an indirect pecuniary interest in 870,873 shares of Common Stock reported in column 5 of Table I directly held by 667, a limited partnership of which the sole general partner is Baker Biotech Capital, L.P., a limited partnership of which the sole general partner is Baker Biotech Capital (GP),LLC, due to their interest in 667 and Baker Biotech Capital, L.P.'s right to receive an allocation of a portion of the profits from 667 and the 5,188 shares of Common Stock reported in column 5 of Table I held directly by the Adviser.

F4 · ownership.nature: In addition, each of the Funds has the right to receive a portion of the 41,500 options reported in column 9 of Table II held directly by Dr. Neu.

F6 · ownership.nature: The Adviser serves as the investment adviser to the Funds. In connection with the services provided by the Adviser, the Adviser receives an asset-based management fee that does not confer any pecuniary interest in the securities held by the Funds. The Adviser GP is the Adviser's sole general partner. Julian C. Baker and Felix J. Baker are managing members of the Adviser GP. The Adviser has complete and unlimited discretion and authority with respect to the investment and voting power of the securities held by the Funds. The general partners of the Funds relinquished to the Adviser all discretion and authority with respect to the investment and voting power of the securities held by the Funds.

F7 · ownership.nature: Julian C. Baker, Felix J. Baker, the Adviser GP and the Adviser disclaim beneficial ownership of the securities held directly by the Funds except to the extent of their pecuniary interest therein, and this report shall not be deemed an admission that any of Julian C. Baker, Felix J. Baker, the Adviser GP or the Adviser is a beneficial owner of such securities for purposes of Section 16 or any other purpose.

F8 · ownership.nature: The policy of the Funds and the Adviser, and the Nominee Agreement (as defined below) do not permit former employees of the Adviser or managing members of the Adviser GP to receive compensation for serving as a director of the Issuer, and the Funds are instead entitled to the pecuniary interest in the Common Stock received from the exercise of the Stock Options.

F9 · ownership.nature: Solely as a result of their ownership interest in (i) the general partners of the Funds and (ii) the Funds as limited partners, Felix J. Baker and Julian C. Baker may be deemed to have an indirect pecuniary interest in the shares issued upon exercise of the Stock Options (i.e. no direct pecuniary interest).

F11 · ownership.nature: The disclosure of the exercise of Stock Options for Common Stock reported on this form is a single exercise of 5,188 shares. The 5,188 shares are reported for each of the Funds as each has an indirect pecuniary interest.

F12 · ownership.nature: Dr. Neu entered into a Nominee Agreement (the "Nominee Agreement") with the Adviser on January 23, 2021. Pursuant to the Nominee Agreement, Dr. Neu agreed that, with respect to the Stock Options and Common Stock from the exercise of Stock Options, the Adviser will have dispositive power as well as the ability to control the timing of exercise of the Stock Options and that any proceeds from the sale of the Common Stock will be remitted to the Adviser net of brokerage commissions consistent with the policies of the Adviser for current employees.

SEC source: 0001638599-21-000113 · doc4_7019.xml · nonDerivative · entry 2

BAKER BROS. ADVISORS LP · CIK 0001263508 · Director · 10% owner

667, L.P. · CIK 0001551139 · Director · 10% owner

Baker Bros. Advisors (GP) LLC · CIK 0001580575 · Director · 10% owner

Baker Brothers Life Sciences LP · CIK 0001363364 · Director · 10% owner

BAKER FELIX · CIK 0001087940 · Director · 10% owner

BAKER JULIAN · CIK 0001087939 · Director · 10% owner

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: Not disclosed

Ownership: Indirect · See Footnotes

Disclosed balance after: 9,252,951

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F5 · ownership.direct: After giving effect to the transaction reported herein and as a result of their ownership interest in (i) Baker Brothers Life Sciences Capital, L.P. and (ii) Baker Brothers Life Sciences, L.P. ("Life Sciences", and together with 667, the "Funds"), Julian C. Baker and Felix J. Baker each may be deemed to have an indirect pecuniary interest in 9,247,763 shares of Common Stock reported in column 5 of Table I directly held by Life Sciences, a limited partnership of which the sole general partner is Baker Brothers Life Sciences Capital, L.P., a limited partnership of which the sole general partner is Baker Brothers Life Sciences Capital (GP),LLC, due to their interest in Life Sciences and Baker Brothers Life Sciences Capital, L.P.'s right to receive an allocation of a portion of the profits from Life Sciences and the 5,188 shares of Common Stock reported in column 5 of Table I held directly by the Adviser.

F1 · ownership.nature: Common stock ("Common Stock") of Prelude Therapeutics Incorporated (the "Issuer") received upon exercise of 5,188 non-qualified stock options exercisable into Common Stock on a 1-for-1 basis ("Stock Options") that were issued to Dr. Kelvin M. Neu, a former employee of Baker Bros. Advisors LP (the "Adviser") and former director of the board of directors of the Issuer (the "Board"), in his capacity as a former director of the Issuer are reflected in the ownership of each of the Funds (as defined below). The Stock Options with a strike price of $12.85 per share, vested in 36 equal monthly installments beginning on October 24, 2020, subject to an individual designated by the Adviser continuing to serve on the Board.

F2 · ownership.nature: Dr. Neu and Julian C. Baker, a managing member of Baker Bros. Advisors (GP) LLC (the "Adviser GP") and current director of the Issuer pursuant to the policies of the Adviser, do not have any right to the pecuniary interest in the Stock Options issued or the Common Stock received upon exercise of such Stock Options for either Dr. Neu's past service on the the Board or Julian C. Baker's current service on the Board Each of the Funds owns an indirect proportionate pecuniary interest in the Common Stock received upon exercise of the Stock Options issued in connection with Dr. Neu's past service on the Board and Julian C. Baker's current service on the Board, less the exercise cost of those options.

F5 · ownership.nature: After giving effect to the transaction reported herein and as a result of their ownership interest in (i) Baker Brothers Life Sciences Capital, L.P. and (ii) Baker Brothers Life Sciences, L.P. ("Life Sciences", and together with 667, the "Funds"), Julian C. Baker and Felix J. Baker each may be deemed to have an indirect pecuniary interest in 9,247,763 shares of Common Stock reported in column 5 of Table I directly held by Life Sciences, a limited partnership of which the sole general partner is Baker Brothers Life Sciences Capital, L.P., a limited partnership of which the sole general partner is Baker Brothers Life Sciences Capital (GP),LLC, due to their interest in Life Sciences and Baker Brothers Life Sciences Capital, L.P.'s right to receive an allocation of a portion of the profits from Life Sciences and the 5,188 shares of Common Stock reported in column 5 of Table I held directly by the Adviser.

F6 · ownership.nature: The Adviser serves as the investment adviser to the Funds. In connection with the services provided by the Adviser, the Adviser receives an asset-based management fee that does not confer any pecuniary interest in the securities held by the Funds. The Adviser GP is the Adviser's sole general partner. Julian C. Baker and Felix J. Baker are managing members of the Adviser GP. The Adviser has complete and unlimited discretion and authority with respect to the investment and voting power of the securities held by the Funds. The general partners of the Funds relinquished to the Adviser all discretion and authority with respect to the investment and voting power of the securities held by the Funds.

F7 · ownership.nature: Julian C. Baker, Felix J. Baker, the Adviser GP and the Adviser disclaim beneficial ownership of the securities held directly by the Funds except to the extent of their pecuniary interest therein, and this report shall not be deemed an admission that any of Julian C. Baker, Felix J. Baker, the Adviser GP or the Adviser is a beneficial owner of such securities for purposes of Section 16 or any other purpose.

F8 · ownership.nature: The policy of the Funds and the Adviser, and the Nominee Agreement (as defined below) do not permit former employees of the Adviser or managing members of the Adviser GP to receive compensation for serving as a director of the Issuer, and the Funds are instead entitled to the pecuniary interest in the Common Stock received from the exercise of the Stock Options.

F9 · ownership.nature: Solely as a result of their ownership interest in (i) the general partners of the Funds and (ii) the Funds as limited partners, Felix J. Baker and Julian C. Baker may be deemed to have an indirect pecuniary interest in the shares issued upon exercise of the Stock Options (i.e. no direct pecuniary interest).

F11 · ownership.nature: The disclosure of the exercise of Stock Options for Common Stock reported on this form is a single exercise of 5,188 shares. The 5,188 shares are reported for each of the Funds as each has an indirect pecuniary interest.

F12 · ownership.nature: Dr. Neu entered into a Nominee Agreement (the "Nominee Agreement") with the Adviser on January 23, 2021. Pursuant to the Nominee Agreement, Dr. Neu agreed that, with respect to the Stock Options and Common Stock from the exercise of Stock Options, the Adviser will have dispositive power as well as the ability to control the timing of exercise of the Stock Options and that any proceeds from the sale of the Common Stock will be remitted to the Adviser net of brokerage commissions consistent with the policies of the Adviser for current employees.

SEC source: 0001638599-21-000113 · doc4_7019.xml · nonDerivative · entry 1

BAKER BROS. ADVISORS LP · CIK 0001263508 · Director · 10% owner

667, L.P. · CIK 0001551139 · Director · 10% owner

Baker Bros. Advisors (GP) LLC · CIK 0001580575 · Director · 10% owner

Baker Brothers Life Sciences LP · CIK 0001363364 · Director · 10% owner

BAKER FELIX · CIK 0001087940 · Director · 10% owner

BAKER JULIAN · CIK 0001087939 · Director · 10% owner

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: Not disclosed

Ownership: Indirect · See Footnotes

Disclosed balance after: 876,061

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F3 · ownership.direct: After giving effect to the transaction reported herein and as a result of their ownership interest in (i) Baker Biotech Capital, L.P. and (ii) 667, L.P. ("667"), Julian C. Baker and Felix J. Baker each may be deemed to have an indirect pecuniary interest in 870,873 shares of Common Stock reported in column 5 of Table I directly held by 667, a limited partnership of which the sole general partner is Baker Biotech Capital, L.P., a limited partnership of which the sole general partner is Baker Biotech Capital (GP),LLC, due to their interest in 667 and Baker Biotech Capital, L.P.'s right to receive an allocation of a portion of the profits from 667 and the 5,188 shares of Common Stock reported in column 5 of Table I held directly by the Adviser.

F1 · ownership.nature: Common stock ("Common Stock") of Prelude Therapeutics Incorporated (the "Issuer") received upon exercise of 5,188 non-qualified stock options exercisable into Common Stock on a 1-for-1 basis ("Stock Options") that were issued to Dr. Kelvin M. Neu, a former employee of Baker Bros. Advisors LP (the "Adviser") and former director of the board of directors of the Issuer (the "Board"), in his capacity as a former director of the Issuer are reflected in the ownership of each of the Funds (as defined below). The Stock Options with a strike price of $12.85 per share, vested in 36 equal monthly installments beginning on October 24, 2020, subject to an individual designated by the Adviser continuing to serve on the Board.

F2 · ownership.nature: Dr. Neu and Julian C. Baker, a managing member of Baker Bros. Advisors (GP) LLC (the "Adviser GP") and current director of the Issuer pursuant to the policies of the Adviser, do not have any right to the pecuniary interest in the Stock Options issued or the Common Stock received upon exercise of such Stock Options for either Dr. Neu's past service on the the Board or Julian C. Baker's current service on the Board Each of the Funds owns an indirect proportionate pecuniary interest in the Common Stock received upon exercise of the Stock Options issued in connection with Dr. Neu's past service on the Board and Julian C. Baker's current service on the Board, less the exercise cost of those options.

F3 · ownership.nature: After giving effect to the transaction reported herein and as a result of their ownership interest in (i) Baker Biotech Capital, L.P. and (ii) 667, L.P. ("667"), Julian C. Baker and Felix J. Baker each may be deemed to have an indirect pecuniary interest in 870,873 shares of Common Stock reported in column 5 of Table I directly held by 667, a limited partnership of which the sole general partner is Baker Biotech Capital, L.P., a limited partnership of which the sole general partner is Baker Biotech Capital (GP),LLC, due to their interest in 667 and Baker Biotech Capital, L.P.'s right to receive an allocation of a portion of the profits from 667 and the 5,188 shares of Common Stock reported in column 5 of Table I held directly by the Adviser.

F6 · ownership.nature: The Adviser serves as the investment adviser to the Funds. In connection with the services provided by the Adviser, the Adviser receives an asset-based management fee that does not confer any pecuniary interest in the securities held by the Funds. The Adviser GP is the Adviser's sole general partner. Julian C. Baker and Felix J. Baker are managing members of the Adviser GP. The Adviser has complete and unlimited discretion and authority with respect to the investment and voting power of the securities held by the Funds. The general partners of the Funds relinquished to the Adviser all discretion and authority with respect to the investment and voting power of the securities held by the Funds.

F7 · ownership.nature: Julian C. Baker, Felix J. Baker, the Adviser GP and the Adviser disclaim beneficial ownership of the securities held directly by the Funds except to the extent of their pecuniary interest therein, and this report shall not be deemed an admission that any of Julian C. Baker, Felix J. Baker, the Adviser GP or the Adviser is a beneficial owner of such securities for purposes of Section 16 or any other purpose.

F8 · ownership.nature: The policy of the Funds and the Adviser, and the Nominee Agreement (as defined below) do not permit former employees of the Adviser or managing members of the Adviser GP to receive compensation for serving as a director of the Issuer, and the Funds are instead entitled to the pecuniary interest in the Common Stock received from the exercise of the Stock Options.

F9 · ownership.nature: Solely as a result of their ownership interest in (i) the general partners of the Funds and (ii) the Funds as limited partners, Felix J. Baker and Julian C. Baker may be deemed to have an indirect pecuniary interest in the shares issued upon exercise of the Stock Options (i.e. no direct pecuniary interest).

F11 · ownership.nature: The disclosure of the exercise of Stock Options for Common Stock reported on this form is a single exercise of 5,188 shares. The 5,188 shares are reported for each of the Funds as each has an indirect pecuniary interest.

F12 · ownership.nature: Dr. Neu entered into a Nominee Agreement (the "Nominee Agreement") with the Adviser on January 23, 2021. Pursuant to the Nominee Agreement, Dr. Neu agreed that, with respect to the Stock Options and Common Stock from the exercise of Stock Options, the Adviser will have dispositive power as well as the ability to control the timing of exercise of the Stock Options and that any proceeds from the sale of the Common Stock will be remitted to the Adviser net of brokerage commissions consistent with the policies of the Adviser for current employees.

SEC source: 0000947871-21-000054 · ownership.xml · derivative · entry 1

ORBIMED ADVISORS LLC · CIK 0001055951 · Director · 10% owner

OrbiMed Capital GP VI LLC · CIK 0001682115 · 10% owner

ORBIMED CAPITAL LLC · CIK 0001157524 · Director · 10% owner

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: Not disclosed

Ownership: Indirect · See Footnotes

Disclosed balance after: 5,596,886

Underlying: Common Stock · 41,700 shares

Expires not disclosed

F1 · derivative.exercise_price: These shares of the Issuer's common stock ("Shares") were purchased in the Company's underwritten public offering. Each share of the Issuer's Non-Voting Common Stock is convertible into one share of the Issuer's Common Stock at any time at the option of the holder without consideration subject to a 9.99% beneficial ownership limitation which may be increased or decreased by the holder upon 61 days' notice to the Issuer.

F1 · derivative.exercise_date: These shares of the Issuer's common stock ("Shares") were purchased in the Company's underwritten public offering. Each share of the Issuer's Non-Voting Common Stock is convertible into one share of the Issuer's Common Stock at any time at the option of the holder without consideration subject to a 9.99% beneficial ownership limitation which may be increased or decreased by the holder upon 61 days' notice to the Issuer.

F1 · derivative.expiration_date: These shares of the Issuer's common stock ("Shares") were purchased in the Company's underwritten public offering. Each share of the Issuer's Non-Voting Common Stock is convertible into one share of the Issuer's Common Stock at any time at the option of the holder without consideration subject to a 9.99% beneficial ownership limitation which may be increased or decreased by the holder upon 61 days' notice to the Issuer.

F2 · ownership.nature: The Shares are held of record by OrbiMed Private Investments VI, LP ("OPI VI"). OrbiMed Capital GP VI LLC ("GP VI") is the general partner of OPI VI and OrbiMed Advisors LLC ("OrbiMed Advisors") is the managing member of OrbiMed GP VI. OrbiMed GP VI and OrbiMed Advisors may be deemed to have voting and investment power over the securities held by OPI VI and may be deemed to have beneficial ownership over such securities. OrbiMed Advisors exercises voting and investment power through a management committee comprised of Carl L. Gordon, Sven H. Borho, and Jonathan T. Silverstein, each of whom disclaims beneficial ownership of the Shares held by OPI VI.

F3 · ownership.nature: This report on Form 4 is filed by OrbiMed Advisors, OrbiMed GP VI, and OrbiMed Capital LLC ("OrbiMed Capital"). Each of the Reporting Persons disclaims beneficial ownership of the securities reported herein for purposes of Rule 16a-1(a) under the Securities Exchange Act of 1934, as amended (the "Exchange Act"), except to the extent of its pecuniary interest therein, if any. The Reporting Persons have designated David Bonita, a member of OrbiMed Advisors, to serve on the Issuer's board of directors. This report on Form 4 shall not be deemed an admission that any of the Reporting Persons, or David Bonita, is a beneficial owner of such securities for the purpose of Section 16 of the Exchange Act, or for any other purpose.

SEC source: 0000947871-21-000053 · ownership.xml · derivative · entry 1

Bonita David P · CIK 0001572451 · Director · 10% owner

10b5-1 filing: Not disclosed

Ownership: Indirect · See Footnotes

Disclosed balance after: 5,596,886

Underlying: Common Stock · 41,700 shares

Expires not disclosed

F1 · derivative.exercise_price: These shares of the Issuer's common stock ("Shares") were purchased in the Company's underwritten public offering. Each share of the Issuer's Non-Voting Common Stock is convertible into one share of the Issuer's Common Stock at any time at the option of the holder without consideration subject to a 9.99% beneficial ownership limitation which may be increased or decreased by the holder upon 61 days' notice to the Issuer.

F1 · derivative.exercise_date: These shares of the Issuer's common stock ("Shares") were purchased in the Company's underwritten public offering. Each share of the Issuer's Non-Voting Common Stock is convertible into one share of the Issuer's Common Stock at any time at the option of the holder without consideration subject to a 9.99% beneficial ownership limitation which may be increased or decreased by the holder upon 61 days' notice to the Issuer.

F1 · derivative.expiration_date: These shares of the Issuer's common stock ("Shares") were purchased in the Company's underwritten public offering. Each share of the Issuer's Non-Voting Common Stock is convertible into one share of the Issuer's Common Stock at any time at the option of the holder without consideration subject to a 9.99% beneficial ownership limitation which may be increased or decreased by the holder upon 61 days' notice to the Issuer.

F2 · ownership.nature: The Shares are held of record by OrbiMed Private Investments VI, LP ("OPI VI"). OrbiMed Capital GP VI LLC ("GP VI") is the general partner of OPI VI and OrbiMed Advisors LLC ("OrbiMed Advisors") is the managing member of OrbiMed GP VI. OrbiMed GP VI and OrbiMed Advisors may be deemed to have voting and investment power over the securities held by OPI VI and may be deemed to have beneficial ownership over such securities. OrbiMed Advisors exercises voting and investment power through a management committee comprised of Carl L. Gordon, Sven H. Borho, and Jonathan T. Silverstein, each of whom disclaims beneficial ownership of the Shares held by OPI VI. The Reporting Person is a member of OrbiMed Advisors.

F3 · ownership.nature: Each of the Reporting Person, OrbiMed Advisors, OrbiMed GP VI, and OrbiMed Capital LLC ("OrbiMed Capital") disclaims beneficial ownership of the securities reported herein for purposes of Rule 16a-1(a) under the Securities Exchange Act of 1934, as amended (the "Exchange Act"), except to the extent of its or his pecuniary interest therein, if any. This report on Form 4 shall not be deemed an admission that any such entity or person, including the Reporting Person, is a beneficial owner of such securities for the purpose of Section 16 of the Exchange Act, or for any other purpose.

SEC source: 0001638599-21-000064 · doc4_6992.xml · derivative · entry 2

BAKER BROS. ADVISORS LP · CIK 0001263508 · Director · 10% owner

667, L.P. · CIK 0001551139 · Director · 10% owner

Baker Bros. Advisors (GP) LLC · CIK 0001580575 · Director · 10% owner

Baker Brothers Life Sciences LP · CIK 0001363364 · Director · 10% owner

BAKER FELIX · CIK 0001087940 · Director · 10% owner

BAKER JULIAN · CIK 0001087939 · Director · 10% owner

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: Not disclosed

Ownership: Indirect · See Footnotes

Disclosed balance after: 5,212,371

Underlying: Common Stock · 154,222 shares

Expires not disclosed

F1 · derivative.exercise_price: 667, L.P. ("667") and Baker Brothers Life Sciences, L.P. ("Life Sciences" and together with 667, the "Funds") purchased 12,444 and 154,222 shares of non-voting common stock ("Non-Voting Common Stock") of Prelude Therapeutics Incorporated (the "Issuer"), respectively, for $60.00 per share pursuant to an underwritten offering that closed on January 11, 2021. The Non-Voting Common Stock have no expiration date and are convertible immediately at any time at the option of the holder on a 1-for-1 basis without consideration into common stock of the Issuer ("Common Stock") to the extent that after giving effect to such conversion the holders thereof, together with their affiliates and any members of a Section 13(d) group with such holders, would beneficially own, for purposes of Rule 13d-3 under the Securities Act of 1934, as amended, no more than 9.99% of the outstanding shares of Common Stock (the "Beneficial Ownership Limitation") immediately prior to and following such conversion.

F2 · derivative.exercise_price: By written notice to the Issuer, the Funds may from time to time increase or decrease the Beneficial Ownership Limitation applicable to that Fund to any other percentage not in excess of 19.99%. Any such change will not be effective until the 61st day after such notice is delivered to the Issuer.

F1 · shares: 667, L.P. ("667") and Baker Brothers Life Sciences, L.P. ("Life Sciences" and together with 667, the "Funds") purchased 12,444 and 154,222 shares of non-voting common stock ("Non-Voting Common Stock") of Prelude Therapeutics Incorporated (the "Issuer"), respectively, for $60.00 per share pursuant to an underwritten offering that closed on January 11, 2021. The Non-Voting Common Stock have no expiration date and are convertible immediately at any time at the option of the holder on a 1-for-1 basis without consideration into common stock of the Issuer ("Common Stock") to the extent that after giving effect to such conversion the holders thereof, together with their affiliates and any members of a Section 13(d) group with such holders, would beneficially own, for purposes of Rule 13d-3 under the Securities Act of 1934, as amended, no more than 9.99% of the outstanding shares of Common Stock (the "Beneficial Ownership Limitation") immediately prior to and following such conversion.

F2 · shares: By written notice to the Issuer, the Funds may from time to time increase or decrease the Beneficial Ownership Limitation applicable to that Fund to any other percentage not in excess of 19.99%. Any such change will not be effective until the 61st day after such notice is delivered to the Issuer.

F1 · derivative.exercise_date: 667, L.P. ("667") and Baker Brothers Life Sciences, L.P. ("Life Sciences" and together with 667, the "Funds") purchased 12,444 and 154,222 shares of non-voting common stock ("Non-Voting Common Stock") of Prelude Therapeutics Incorporated (the "Issuer"), respectively, for $60.00 per share pursuant to an underwritten offering that closed on January 11, 2021. The Non-Voting Common Stock have no expiration date and are convertible immediately at any time at the option of the holder on a 1-for-1 basis without consideration into common stock of the Issuer ("Common Stock") to the extent that after giving effect to such conversion the holders thereof, together with their affiliates and any members of a Section 13(d) group with such holders, would beneficially own, for purposes of Rule 13d-3 under the Securities Act of 1934, as amended, no more than 9.99% of the outstanding shares of Common Stock (the "Beneficial Ownership Limitation") immediately prior to and following such conversion.

F2 · derivative.exercise_date: By written notice to the Issuer, the Funds may from time to time increase or decrease the Beneficial Ownership Limitation applicable to that Fund to any other percentage not in excess of 19.99%. Any such change will not be effective until the 61st day after such notice is delivered to the Issuer.

F1 · derivative.expiration_date: 667, L.P. ("667") and Baker Brothers Life Sciences, L.P. ("Life Sciences" and together with 667, the "Funds") purchased 12,444 and 154,222 shares of non-voting common stock ("Non-Voting Common Stock") of Prelude Therapeutics Incorporated (the "Issuer"), respectively, for $60.00 per share pursuant to an underwritten offering that closed on January 11, 2021. The Non-Voting Common Stock have no expiration date and are convertible immediately at any time at the option of the holder on a 1-for-1 basis without consideration into common stock of the Issuer ("Common Stock") to the extent that after giving effect to such conversion the holders thereof, together with their affiliates and any members of a Section 13(d) group with such holders, would beneficially own, for purposes of Rule 13d-3 under the Securities Act of 1934, as amended, no more than 9.99% of the outstanding shares of Common Stock (the "Beneficial Ownership Limitation") immediately prior to and following such conversion.

F2 · derivative.expiration_date: By written notice to the Issuer, the Funds may from time to time increase or decrease the Beneficial Ownership Limitation applicable to that Fund to any other percentage not in excess of 19.99%. Any such change will not be effective until the 61st day after such notice is delivered to the Issuer.

F4 · ownership.nature: After giving effect to the transaction reported herein and as a result of their ownership interest in (i) Baker Brothers Life Sciences Capital L.P. and (ii) Life Sciences, Felix J. Baker and Julian C. Baker may be deemed to have an indirect pecuniary interest in Non-Voting Common Stock reported in column 9 of Table II directly held by Life Sciences, a limited partnership of which the sole general partner is Baker Brothers Life Sciences Capital, L.P., a limited partnership of which the sole general partner is Baker Brothers Life Sciences Capital (GP), LLC, due to their interest in Life Sciences and Baker Brothers Life Sciences Capital, L.P.'s right to receive an allocation of a portion of the profits from Life Sciences.

F5 · ownership.nature: Baker Bros. Advisors LP (the "Adviser") serves as the investment adviser to the Funds. In connection with the services provided by the Adviser, the Adviser receives an asset-based management fee that does not confer any pecuniary interest in the securities held by the Funds. Baker Bros. Advisors (GP) LLC (the "Adviser GP") is the Adviser's sole general partner. Julian C. Baker and Felix J. Baker are managing members of the Adviser GP. The Adviser has complete and unlimited discretion and authority with respect to the investment and voting power of the securities held by the Funds. The general partners of the Funds relinquished to the Adviser all discretion and authority with respect to the investment and voting power of the securities held by the Funds.

F6 · ownership.nature: Julian C. Baker, Felix J. Baker, the Adviser GP and the Adviser disclaim beneficial ownership of the securities held directly by the Funds except to the extent of their pecuniary interest therein, and this report shall not be deemed an admission that any of Julian C. Baker, Felix J. Baker, the Adviser GP or the Adviser is a beneficial owner of such securities for purposes of Section 16 or any other purpose.

SEC source: 0001638599-21-000064 · doc4_6992.xml · derivative · entry 1

BAKER BROS. ADVISORS LP · CIK 0001263508 · Director · 10% owner

667, L.P. · CIK 0001551139 · Director · 10% owner

Baker Bros. Advisors (GP) LLC · CIK 0001580575 · Director · 10% owner

Baker Brothers Life Sciences LP · CIK 0001363364 · Director · 10% owner

BAKER FELIX · CIK 0001087940 · Director · 10% owner

BAKER JULIAN · CIK 0001087939 · Director · 10% owner

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: Not disclosed

Ownership: Indirect · See Footnotes

Disclosed balance after: 509,480

Underlying: Common Stock · 12,444 shares

Expires not disclosed

F1 · derivative.exercise_price: 667, L.P. ("667") and Baker Brothers Life Sciences, L.P. ("Life Sciences" and together with 667, the "Funds") purchased 12,444 and 154,222 shares of non-voting common stock ("Non-Voting Common Stock") of Prelude Therapeutics Incorporated (the "Issuer"), respectively, for $60.00 per share pursuant to an underwritten offering that closed on January 11, 2021. The Non-Voting Common Stock have no expiration date and are convertible immediately at any time at the option of the holder on a 1-for-1 basis without consideration into common stock of the Issuer ("Common Stock") to the extent that after giving effect to such conversion the holders thereof, together with their affiliates and any members of a Section 13(d) group with such holders, would beneficially own, for purposes of Rule 13d-3 under the Securities Act of 1934, as amended, no more than 9.99% of the outstanding shares of Common Stock (the "Beneficial Ownership Limitation") immediately prior to and following such conversion.

F2 · derivative.exercise_price: By written notice to the Issuer, the Funds may from time to time increase or decrease the Beneficial Ownership Limitation applicable to that Fund to any other percentage not in excess of 19.99%. Any such change will not be effective until the 61st day after such notice is delivered to the Issuer.

F1 · shares: 667, L.P. ("667") and Baker Brothers Life Sciences, L.P. ("Life Sciences" and together with 667, the "Funds") purchased 12,444 and 154,222 shares of non-voting common stock ("Non-Voting Common Stock") of Prelude Therapeutics Incorporated (the "Issuer"), respectively, for $60.00 per share pursuant to an underwritten offering that closed on January 11, 2021. The Non-Voting Common Stock have no expiration date and are convertible immediately at any time at the option of the holder on a 1-for-1 basis without consideration into common stock of the Issuer ("Common Stock") to the extent that after giving effect to such conversion the holders thereof, together with their affiliates and any members of a Section 13(d) group with such holders, would beneficially own, for purposes of Rule 13d-3 under the Securities Act of 1934, as amended, no more than 9.99% of the outstanding shares of Common Stock (the "Beneficial Ownership Limitation") immediately prior to and following such conversion.

F2 · shares: By written notice to the Issuer, the Funds may from time to time increase or decrease the Beneficial Ownership Limitation applicable to that Fund to any other percentage not in excess of 19.99%. Any such change will not be effective until the 61st day after such notice is delivered to the Issuer.

F1 · derivative.exercise_date: 667, L.P. ("667") and Baker Brothers Life Sciences, L.P. ("Life Sciences" and together with 667, the "Funds") purchased 12,444 and 154,222 shares of non-voting common stock ("Non-Voting Common Stock") of Prelude Therapeutics Incorporated (the "Issuer"), respectively, for $60.00 per share pursuant to an underwritten offering that closed on January 11, 2021. The Non-Voting Common Stock have no expiration date and are convertible immediately at any time at the option of the holder on a 1-for-1 basis without consideration into common stock of the Issuer ("Common Stock") to the extent that after giving effect to such conversion the holders thereof, together with their affiliates and any members of a Section 13(d) group with such holders, would beneficially own, for purposes of Rule 13d-3 under the Securities Act of 1934, as amended, no more than 9.99% of the outstanding shares of Common Stock (the "Beneficial Ownership Limitation") immediately prior to and following such conversion.

F2 · derivative.exercise_date: By written notice to the Issuer, the Funds may from time to time increase or decrease the Beneficial Ownership Limitation applicable to that Fund to any other percentage not in excess of 19.99%. Any such change will not be effective until the 61st day after such notice is delivered to the Issuer.

F1 · derivative.expiration_date: 667, L.P. ("667") and Baker Brothers Life Sciences, L.P. ("Life Sciences" and together with 667, the "Funds") purchased 12,444 and 154,222 shares of non-voting common stock ("Non-Voting Common Stock") of Prelude Therapeutics Incorporated (the "Issuer"), respectively, for $60.00 per share pursuant to an underwritten offering that closed on January 11, 2021. The Non-Voting Common Stock have no expiration date and are convertible immediately at any time at the option of the holder on a 1-for-1 basis without consideration into common stock of the Issuer ("Common Stock") to the extent that after giving effect to such conversion the holders thereof, together with their affiliates and any members of a Section 13(d) group with such holders, would beneficially own, for purposes of Rule 13d-3 under the Securities Act of 1934, as amended, no more than 9.99% of the outstanding shares of Common Stock (the "Beneficial Ownership Limitation") immediately prior to and following such conversion.

F2 · derivative.expiration_date: By written notice to the Issuer, the Funds may from time to time increase or decrease the Beneficial Ownership Limitation applicable to that Fund to any other percentage not in excess of 19.99%. Any such change will not be effective until the 61st day after such notice is delivered to the Issuer.

F3 · ownership.nature: After giving effect to the transaction reported herein and as a result of their ownership interest in (i) Baker Biotech Capital, L.P. and (ii) 667, Julian C. Baker and Felix J. Baker each may be deemed to have an indirect pecuniary interest in the Non-Voting Common Stock reported in column 9 of Table II directly held by 667, a limited partnership of which the sole general partner is Baker Biotech Capital, L.P., a limited partnership of which the sole general partner is Baker Biotech Capital (GP), LLC, due to their interest in 667 and Baker Biotech Capital, L.P.'s right to receive an allocation of a portion of the profits from 667.

F5 · ownership.nature: Baker Bros. Advisors LP (the "Adviser") serves as the investment adviser to the Funds. In connection with the services provided by the Adviser, the Adviser receives an asset-based management fee that does not confer any pecuniary interest in the securities held by the Funds. Baker Bros. Advisors (GP) LLC (the "Adviser GP") is the Adviser's sole general partner. Julian C. Baker and Felix J. Baker are managing members of the Adviser GP. The Adviser has complete and unlimited discretion and authority with respect to the investment and voting power of the securities held by the Funds. The general partners of the Funds relinquished to the Adviser all discretion and authority with respect to the investment and voting power of the securities held by the Funds.

F6 · ownership.nature: Julian C. Baker, Felix J. Baker, the Adviser GP and the Adviser disclaim beneficial ownership of the securities held directly by the Funds except to the extent of their pecuniary interest therein, and this report shall not be deemed an admission that any of Julian C. Baker, Felix J. Baker, the Adviser GP or the Adviser is a beneficial owner of such securities for purposes of Section 16 or any other purpose.

SEC source: 0001209191-20-052404 · doc4.xml · derivative · entry 10

ORBIMED ADVISORS LLC · CIK 0001055951 · Director · 10% owner

OrbiMed Capital GP VI LLC · CIK 0001682115 · Director · 10% owner

ORBIMED CAPITAL LLC · CIK 0001157524 · Director · 10% owner

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: Not disclosed

Ownership: Indirect · See footnote

Disclosed balance after: 5,555,186

Underlying: Common Stock · 5,555,186 shares

Expires not disclosed

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F5 · derivative.exercise_price: Each share of the Issuer's Series A Preferred Stock, Series B Preferred Stock, and Series C Preferred Stock automatically converted into one share of the Issuer's Non-Voting Common Stock immediately prior to the closing of the Issuer's initial public offering and has no expiration date. Each share of the Issuer's Non-Voting Common Stock is convertible into one share of the Issuer's Common Stock at any time at the option of the holder without consideration subject to a 9.99% beneficial ownership limitation which may be increased or decreased by the holder upon 61 days' notice to the Issuer.

F5 · price: Each share of the Issuer's Series A Preferred Stock, Series B Preferred Stock, and Series C Preferred Stock automatically converted into one share of the Issuer's Non-Voting Common Stock immediately prior to the closing of the Issuer's initial public offering and has no expiration date. Each share of the Issuer's Non-Voting Common Stock is convertible into one share of the Issuer's Common Stock at any time at the option of the holder without consideration subject to a 9.99% beneficial ownership limitation which may be increased or decreased by the holder upon 61 days' notice to the Issuer.

F5 · derivative.exercise_date: Each share of the Issuer's Series A Preferred Stock, Series B Preferred Stock, and Series C Preferred Stock automatically converted into one share of the Issuer's Non-Voting Common Stock immediately prior to the closing of the Issuer's initial public offering and has no expiration date. Each share of the Issuer's Non-Voting Common Stock is convertible into one share of the Issuer's Common Stock at any time at the option of the holder without consideration subject to a 9.99% beneficial ownership limitation which may be increased or decreased by the holder upon 61 days' notice to the Issuer.

F5 · derivative.expiration_date: Each share of the Issuer's Series A Preferred Stock, Series B Preferred Stock, and Series C Preferred Stock automatically converted into one share of the Issuer's Non-Voting Common Stock immediately prior to the closing of the Issuer's initial public offering and has no expiration date. Each share of the Issuer's Non-Voting Common Stock is convertible into one share of the Issuer's Common Stock at any time at the option of the holder without consideration subject to a 9.99% beneficial ownership limitation which may be increased or decreased by the holder upon 61 days' notice to the Issuer.

F2 · ownership.nature: This report on Form 4 is jointly filed by OrbiMed Advisors, OrbiMed Capital GP VI LLC ("GP VI"), and OrbiMed Capital. Each of the Reporting Persons disclaims beneficial ownership of the securities reported herein for purposes of Rule 16a-1(a) under the Exchange Act, except to the extent of its pecuniary interest therein, if any. This report shall not be deemed an admission that any such entity is a beneficial owner of such securities for purpose of Section 16 of the Exchange Act, or for any other purpose. The Reporting Persons have designated a representative, David Bonita, a member of OrbiMed Advisors, to serve on the Issuer's board of directors.

F3 · ownership.nature: These securities are held of record by OrbiMed Private Investments VI, L.P. ("OPI VI"). GP VI is the general partner of OPI VI and OrbiMed Advisors is the managing member of GP VI. By virtue of such relationships, GP VI and OrbiMed Advisors may be deemed to have voting power and investment power over the securities held by OPI VI and as a result, may be deemed to have beneficial ownership over such securities. OrbiMed Advisors exercises voting and investment power through a management committee comprised of Carl L. Gordon, Sven H. Borho, and Jonathan T. Silverstein, each of whom disclaims beneficial ownership of the shares held by OPI VI.

SEC source: 0001209191-20-052404 · doc4.xml · derivative · entry 9

ORBIMED ADVISORS LLC · CIK 0001055951 · Director · 10% owner

OrbiMed Capital GP VI LLC · CIK 0001682115 · Director · 10% owner

ORBIMED CAPITAL LLC · CIK 0001157524 · Director · 10% owner

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: Not disclosed

Ownership: Indirect · See footnote

Disclosed balance after: 0

Underlying: Non-Voting Common Stock · 413,234 shares

Expires not disclosed

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F5 · derivative.exercise_price: Each share of the Issuer's Series A Preferred Stock, Series B Preferred Stock, and Series C Preferred Stock automatically converted into one share of the Issuer's Non-Voting Common Stock immediately prior to the closing of the Issuer's initial public offering and has no expiration date. Each share of the Issuer's Non-Voting Common Stock is convertible into one share of the Issuer's Common Stock at any time at the option of the holder without consideration subject to a 9.99% beneficial ownership limitation which may be increased or decreased by the holder upon 61 days' notice to the Issuer.

F5 · price: Each share of the Issuer's Series A Preferred Stock, Series B Preferred Stock, and Series C Preferred Stock automatically converted into one share of the Issuer's Non-Voting Common Stock immediately prior to the closing of the Issuer's initial public offering and has no expiration date. Each share of the Issuer's Non-Voting Common Stock is convertible into one share of the Issuer's Common Stock at any time at the option of the holder without consideration subject to a 9.99% beneficial ownership limitation which may be increased or decreased by the holder upon 61 days' notice to the Issuer.

F5 · derivative.exercise_date: Each share of the Issuer's Series A Preferred Stock, Series B Preferred Stock, and Series C Preferred Stock automatically converted into one share of the Issuer's Non-Voting Common Stock immediately prior to the closing of the Issuer's initial public offering and has no expiration date. Each share of the Issuer's Non-Voting Common Stock is convertible into one share of the Issuer's Common Stock at any time at the option of the holder without consideration subject to a 9.99% beneficial ownership limitation which may be increased or decreased by the holder upon 61 days' notice to the Issuer.

F5 · derivative.expiration_date: Each share of the Issuer's Series A Preferred Stock, Series B Preferred Stock, and Series C Preferred Stock automatically converted into one share of the Issuer's Non-Voting Common Stock immediately prior to the closing of the Issuer's initial public offering and has no expiration date. Each share of the Issuer's Non-Voting Common Stock is convertible into one share of the Issuer's Common Stock at any time at the option of the holder without consideration subject to a 9.99% beneficial ownership limitation which may be increased or decreased by the holder upon 61 days' notice to the Issuer.

F2 · ownership.nature: This report on Form 4 is jointly filed by OrbiMed Advisors, OrbiMed Capital GP VI LLC ("GP VI"), and OrbiMed Capital. Each of the Reporting Persons disclaims beneficial ownership of the securities reported herein for purposes of Rule 16a-1(a) under the Exchange Act, except to the extent of its pecuniary interest therein, if any. This report shall not be deemed an admission that any such entity is a beneficial owner of such securities for purpose of Section 16 of the Exchange Act, or for any other purpose. The Reporting Persons have designated a representative, David Bonita, a member of OrbiMed Advisors, to serve on the Issuer's board of directors.

F3 · ownership.nature: These securities are held of record by OrbiMed Private Investments VI, L.P. ("OPI VI"). GP VI is the general partner of OPI VI and OrbiMed Advisors is the managing member of GP VI. By virtue of such relationships, GP VI and OrbiMed Advisors may be deemed to have voting power and investment power over the securities held by OPI VI and as a result, may be deemed to have beneficial ownership over such securities. OrbiMed Advisors exercises voting and investment power through a management committee comprised of Carl L. Gordon, Sven H. Borho, and Jonathan T. Silverstein, each of whom disclaims beneficial ownership of the shares held by OPI VI.

SEC source: 0001209191-20-052404 · doc4.xml · derivative · entry 8

ORBIMED ADVISORS LLC · CIK 0001055951 · Director · 10% owner

OrbiMed Capital GP VI LLC · CIK 0001682115 · Director · 10% owner

ORBIMED CAPITAL LLC · CIK 0001157524 · Director · 10% owner

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: Not disclosed

Ownership: Indirect · See footnote

Disclosed balance after: 0

Underlying: Common Stock · 619,850 shares

Expires not disclosed

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F4 · derivative.exercise_price: Each share of the Issuer's Series A Preferred Stock, Series B Preferred Stock, and Series C Preferred Stock automatically converted into one share of the Issuer's Common Stock immediately prior to the closing of the Issuer's initial public offering and has no expiration date.

F4 · price: Each share of the Issuer's Series A Preferred Stock, Series B Preferred Stock, and Series C Preferred Stock automatically converted into one share of the Issuer's Common Stock immediately prior to the closing of the Issuer's initial public offering and has no expiration date.

F4 · derivative.exercise_date: Each share of the Issuer's Series A Preferred Stock, Series B Preferred Stock, and Series C Preferred Stock automatically converted into one share of the Issuer's Common Stock immediately prior to the closing of the Issuer's initial public offering and has no expiration date.

F4 · derivative.expiration_date: Each share of the Issuer's Series A Preferred Stock, Series B Preferred Stock, and Series C Preferred Stock automatically converted into one share of the Issuer's Common Stock immediately prior to the closing of the Issuer's initial public offering and has no expiration date.

F2 · ownership.nature: This report on Form 4 is jointly filed by OrbiMed Advisors, OrbiMed Capital GP VI LLC ("GP VI"), and OrbiMed Capital. Each of the Reporting Persons disclaims beneficial ownership of the securities reported herein for purposes of Rule 16a-1(a) under the Exchange Act, except to the extent of its pecuniary interest therein, if any. This report shall not be deemed an admission that any such entity is a beneficial owner of such securities for purpose of Section 16 of the Exchange Act, or for any other purpose. The Reporting Persons have designated a representative, David Bonita, a member of OrbiMed Advisors, to serve on the Issuer's board of directors.

F3 · ownership.nature: These securities are held of record by OrbiMed Private Investments VI, L.P. ("OPI VI"). GP VI is the general partner of OPI VI and OrbiMed Advisors is the managing member of GP VI. By virtue of such relationships, GP VI and OrbiMed Advisors may be deemed to have voting power and investment power over the securities held by OPI VI and as a result, may be deemed to have beneficial ownership over such securities. OrbiMed Advisors exercises voting and investment power through a management committee comprised of Carl L. Gordon, Sven H. Borho, and Jonathan T. Silverstein, each of whom disclaims beneficial ownership of the shares held by OPI VI.

SEC source: 0001209191-20-052404 · doc4.xml · derivative · entry 7

ORBIMED ADVISORS LLC · CIK 0001055951 · Director · 10% owner

OrbiMed Capital GP VI LLC · CIK 0001682115 · Director · 10% owner

ORBIMED CAPITAL LLC · CIK 0001157524 · Director · 10% owner

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: Not disclosed

Ownership: Indirect · See footnote

Disclosed balance after: 0

Underlying: Non-Voting Common Stock · 2,945,458 shares

Expires not disclosed

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F5 · derivative.exercise_price: Each share of the Issuer's Series A Preferred Stock, Series B Preferred Stock, and Series C Preferred Stock automatically converted into one share of the Issuer's Non-Voting Common Stock immediately prior to the closing of the Issuer's initial public offering and has no expiration date. Each share of the Issuer's Non-Voting Common Stock is convertible into one share of the Issuer's Common Stock at any time at the option of the holder without consideration subject to a 9.99% beneficial ownership limitation which may be increased or decreased by the holder upon 61 days' notice to the Issuer.

F5 · price: Each share of the Issuer's Series A Preferred Stock, Series B Preferred Stock, and Series C Preferred Stock automatically converted into one share of the Issuer's Non-Voting Common Stock immediately prior to the closing of the Issuer's initial public offering and has no expiration date. Each share of the Issuer's Non-Voting Common Stock is convertible into one share of the Issuer's Common Stock at any time at the option of the holder without consideration subject to a 9.99% beneficial ownership limitation which may be increased or decreased by the holder upon 61 days' notice to the Issuer.

F5 · derivative.exercise_date: Each share of the Issuer's Series A Preferred Stock, Series B Preferred Stock, and Series C Preferred Stock automatically converted into one share of the Issuer's Non-Voting Common Stock immediately prior to the closing of the Issuer's initial public offering and has no expiration date. Each share of the Issuer's Non-Voting Common Stock is convertible into one share of the Issuer's Common Stock at any time at the option of the holder without consideration subject to a 9.99% beneficial ownership limitation which may be increased or decreased by the holder upon 61 days' notice to the Issuer.

F5 · derivative.expiration_date: Each share of the Issuer's Series A Preferred Stock, Series B Preferred Stock, and Series C Preferred Stock automatically converted into one share of the Issuer's Non-Voting Common Stock immediately prior to the closing of the Issuer's initial public offering and has no expiration date. Each share of the Issuer's Non-Voting Common Stock is convertible into one share of the Issuer's Common Stock at any time at the option of the holder without consideration subject to a 9.99% beneficial ownership limitation which may be increased or decreased by the holder upon 61 days' notice to the Issuer.

F2 · ownership.nature: This report on Form 4 is jointly filed by OrbiMed Advisors, OrbiMed Capital GP VI LLC ("GP VI"), and OrbiMed Capital. Each of the Reporting Persons disclaims beneficial ownership of the securities reported herein for purposes of Rule 16a-1(a) under the Exchange Act, except to the extent of its pecuniary interest therein, if any. This report shall not be deemed an admission that any such entity is a beneficial owner of such securities for purpose of Section 16 of the Exchange Act, or for any other purpose. The Reporting Persons have designated a representative, David Bonita, a member of OrbiMed Advisors, to serve on the Issuer's board of directors.

F3 · ownership.nature: These securities are held of record by OrbiMed Private Investments VI, L.P. ("OPI VI"). GP VI is the general partner of OPI VI and OrbiMed Advisors is the managing member of GP VI. By virtue of such relationships, GP VI and OrbiMed Advisors may be deemed to have voting power and investment power over the securities held by OPI VI and as a result, may be deemed to have beneficial ownership over such securities. OrbiMed Advisors exercises voting and investment power through a management committee comprised of Carl L. Gordon, Sven H. Borho, and Jonathan T. Silverstein, each of whom disclaims beneficial ownership of the shares held by OPI VI.