Security	Conv. / exercise price	Date	Code	Shares	A/D	Exercisable	Expires	Underlying	Underlying shares	Owned after	D/I
Non-Qualified Stock Option (right to buy)^{F1,F2,F3,F4,F5,F6,F7,F8}	$3.94	Jun 9, 2026	A	38,000	A	—	Jun 8, 2036	Common Stock	38,000	38,000	I
Non-Qualified Stock Option (right to buy)^{F1,F2,F4,F5,F6,F7,F8,F9}	$3.94	Jun 9, 2026	A	38,000	A	—	Jun 8, 2036	Common Stock	38,000	38,000	I

Explanation of responses

F1Includes 38,000 non-qualified stock options ("Stock Options") exercisable solely into common stock ("Common Stock") of Prelude Therapeutics Incorporated (the "Issuer") granted by the Issuer to Dr. Paul C. Scherer, a full-time employee of Baker Bros. Advisors LP (the "Adviser"), on June 9, 2026, in his capacity as a director of the Issuer, pursuant to the Issuer's 2020 Equity Incentive Plan (the "Incentive Plan"). The Stock Options have a strike price of $3.94 per share, and vest on the earlier of the first anniversary of the grant date or the date of the next annual meeting of stockholders of the Issuer, subject to Dr. Scherer's continued service on the board of directors of the Issuer (the "Board") through such vesting date or an earlier change in control of the Issuer. The Stock Options expire on June 8, 2036.
F2Dr. Scherer serves on the Board as a representative of 667, L.P. ("667") and Baker Brothers Life Sciences, L.P. ("Life Sciences", and together with 667, the "Funds") and their affiliates and control persons.
F3After 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 Stock Options reported in column 9 of Table II held for the benefit of 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.
F4The 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 for the benefit of 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 for the benefit of 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 for the benefit of the Funds.
F5Julian C. Baker, Felix J. Baker, the Adviser GP and the Adviser disclaim beneficial ownership of the securities held for the benefit of 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.
F6Pursuant to the policies of the Adviser, Dr. Scherer does not have a right to any of the Issuer's securities issued as compensation for his service on the Board and the Funds are entitled to an indirect proportionate pecuniary interest in such securities. The Funds each own an indirect proportionate pecuniary interest in such securities. Solely as a result of their ownership interest in (i) the general partners of the Funds and (ii) the Funds, Felix J. Baker and Julian C. Baker may be deemed to have an indirect pecuniary interest in the shares of Common Stock, Stock Options and Common Stock issued upon exercise of Stock Options (i.e. no direct pecuniary interest) issued as compensation for such Board service.
F7Pursuant to the policies of the Adviser, the Adviser has voting and dispositive power over the Stock Options and any Common Stock received as a result of the exercise of the Stock Options.
F8The acquisition of Stock Options reported on this form represents a single grant to Dr. Scherer of 38,000 Stock Options on Table II. This grant of 38,000 Stock Options to Dr. Scherer is reported for each of the Funds as each has an indirect pecuniary interest in such securities.
F9After 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, Julian C. Baker and Felix J. Baker each may be deemed to have an indirect pecuniary interest in the Stock Options reported in column 9 of Table II held for the benefit of 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.

Remarks

Dr. Paul C. Scherer, a full-time employee of Baker Bros. Advisors LP, is a director of Prelude Therapeutics Incorporated (the "Issuer"). By virtue of their representation on the board of directors of the Issuer, for purposes of Section 16 of the Securities Exchange Act of 1934, as amended, the reporting persons are deemed directors by deputization of the Issuer.