Repare Therapeutics Doses First Patient in Phase 1 Clinical Trial of RP-6306 in Combination with Gemcitabine for the Treatment of Advanced Solid Tumors

Repare Therapeutics Inc. ("Repare" or the "Company") RPTX, a leading clinical-stage precision oncology company enabled by its proprietary synthetic lethality approach to discover and develop novel therapeutics, today announced the first patient has been dosed in the Company's Phase 1 clinical trial of RP-6306, a first-in-class small molecule candidate targeting PKMYT1, in combination with gemcitabine for the treatment of molecularly selected advanced solid tumors (NCT05147272) (the "MAGNETIC" trial).

"Dosing of the first patient in the Phase 1 RP-6306 trial in combination with gemcitabine, alongside our ongoing monotherapy "MYSTIC" trial, is an exciting milestone for Repare as we continue to advance our unique precision oncology pipeline across multiple fronts," said Maria Koehler MD, PhD, Chief Medical Officer of Repare. "MAGNETIC will assess the safety and tolerability of RP-6306 in combination with gemcitabine. It will enroll approximately 104 patients with tumors harboring genomic alterations that were identified through Repare's proprietary STEP² screens. We look forward to providing updates on RP-6306 later in 2022."

This multicenter Phase 1 study aims to determine the maximum tolerated dose (MTD), identify a recommended phase 2 dose (RP2D) and preferred schedule, and assess preliminary anti-tumor activity.

About RP-6306

RP-6306 is a first-in-class, selective, orally available inhibitor of PKMYT1 that was discovered and developed entirely in-house by Repare. Through Repare's SNIPRx screen campaign for targets that are SL with CCNE1 amplification, the Company identified and validated this novel SL gene that has the characteristics of a therapeutic target. Repare has developed novel and selective inhibitors against PKMYT1, which demonstrated compelling pre-clinical anti-tumor activity alone and in combination with certain anticancer agents, and subsequently announced the advancement of a clinical candidate to this potential, first-in-class program.

About Repare Therapeutics, Inc.

Repare Therapeutics is a leading clinical-stage precision oncology company enabled by its proprietary synthetic lethality approach to the discovery and development of novel therapeutics. The Company utilizes its genome-wide, CRISPR-enabled SNIPRx® platform to systematically discover and develop highly targeted cancer therapies focused on genomic instability, including DNA damage repair. The Company's pipeline includes its lead product candidate RP-3500, a potential leading ATR inhibitor, currently in Phase 1/2 clinical development, its second clinical candidate RP-6306, a PKMYT1 inhibitor, currently in Phase 1 clinical development, a Polθ inhibitor program, as well as eight other early-stage, pre-clinical programs. For more information, please visit reparerx.com.

SNIPRx® is a registered trademark of Repare Therapeutics Inc.

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