X0202 SCHEDULE 13G 0002063423 XXXXXXXX LIVE Voting Common Stock, $0.0001 par value per share 09/21/2026 0001783328 TScan Therapeutics, Inc. 89854M101 830 Winter Street Waltham MA 02451 Rule 13d-1(c) Readout Capital, LP DE 0.00 3453388.00 0.00 3453388.00 3453388.00 5.4 IA PN Readout Capital GP, LLC DE 0.00 3453388.00 0.00 3453388.00 3453388.00 5.4 HC Matthew Smith X1 0.00 3453388.00 0.00 3453388.00 3453388.00 5.4 HC IN TScan Therapeutics, Inc. 830 Winter Street, Waltham, MASSACHUSETTS, 02451. This statement is being filed by (i) Readout Capital, LP, ( the "Firm"), (ii) Readout Capital GP, LLC ("Readout GP"), and (iii) Matthew Smith. Each a "Reporting Person." Readout GP is the General Partner to the Firm. Matthew Smit is a Managing Member of Readout GP. The principal business address of each of the Reporting Persons is 1630 Columbia Road NW, Unit 418, Washington, D.C. 20009. See Item 4 of the cover page for each Reporting Person. Y See Item 9 of the cover page for each Reporting Person. By virtue of the Firm's position as the investment manager to Readout Capital Master Fund, LP (the "Master Fund") and the Sub-Advised Funds ("the Sub-Advised Funds"), the direct holders of an aggregate of 3,453,388 of Voting Common Stock, $0.0001 par value per share (the "Common Stock") of TScan Therapeutics, Inc. (the "Issuer"). The Firm may be deemed to exercise voting and investment power over such shares of Common Stock held by the Master Fund and the Sub-Advised Funds, and thus may be deemed to beneficially own such shares of Common Stock. By virtue of its position as the General Partner to the Firm, Readout GP may be deemed to exercise voting and investment power over the shares of Common Stock held directly by the Master Fund and the Sub-Advised Funds, and thus may be deemed to beneficially own such shares of Common Stock. By virtue of Matthew Smith's position as the Managing Member of Readout GP, Matthew Smith may be deemed to exercise voting and investment power over the shares of Common Stock held directly by the Master Fund and the Sub-Advised Funds, and thus may be deemed to beneficially own such shares of Common Stock. Ownership percentages are based on 63,502,667 shares of Common Stock reported as issued and outstanding as of August 7, 2026 in the Issuer's Quarterly Form 10-Q filed with the Securities and Exchange Commission on August 12, 2026. See Item 11 of the cover page for each Reporting Person. See Item 5 of the cover page for each Reporting Person. See Item 6 of the cover page for each Reporting Person. See Item 7 of the cover page for each Reporting Person. See Item 8 of the cover page for each Reporting Person. Y N Y Y Y Y N By signing below I certify that, to the best of my knowledge and belief, the securities referred to above were not acquired and are not held for the purpose of or with the effect of changing or influencing the control of the issuer of the securities and were not acquired and are not held in connection with or as a participant in any transaction having that purpose or effect, other than activities solely in connection with a nomination under § 240.14a-11. Exhibit 1: Joint Filing Agreement Readout Capital, LP Scott Barnes 09/25/2026 Readout Capital GP, LLC Matthew Smith 09/25/2026 Matthew Smith Matthew Smith 09/25/2026