Repare Therapeutics & Debiopharm Announce First Patient Dosed in Phase 1/1b MYTHIC Trial Evaluating the Synthetic Lethal Combination of PKMYT1 and WEE1 Inhibition

Repare Therapeutics Inc. (“Repare” or the “Company”) (Nasdaq: RPTX), a leading clinical-stage precision oncology company, and Debiopharm (www.debiopharm.com), a privately-owned, Swiss-based biopharmaceutical company aiming to establish tomorrow’s standards of care to cure cancer and infectious diseases, today announced that the first patient has been dosed in Module 4 of the ongoing Phase 1/1b MYTHIC (NCT04855656) clinical trial investigating lunresertib in combination with Debio 0123. In this trial, Debiopharm and Repare seek to assess the safety, pharmacokinetics, pharmacodynamics and preliminary clinical activity of this PKMYT1 and WEE1 inhibitor combination.

In early January, Repare and Debiopharm announced a collaboration to evaluate the clinical combination of lunresertib, a first-in-class, selective and potent oral small molecule inhibitor of PKMYT1, and Debio 0123, an oral, brain-penetrant, highly selective WEE1 kinase inhibitor. This collaboration is based on preclinical in vivo data and other data showing rapid, remarkable tumor regressions and high predicted clinical tolerability and represents the first clinical-stage approach to inhibiting both PKMYT1 and WEE1.

“We are excited to have treated our first patient with lunresertib and Debio 0123,” said Maria Koehler, MD, PhD, Executive Vice President and Chief Medical Officer of Repare. “Each of these compounds is well understood and clinically characterized. This combination provides us a unique opportunity to optimize dosing between two selective compounds and overcome limitations inherent to dual-inhibitor approaches. We expect this clinical collaboration will allow us to optimize the excellent synergy we saw preclinically to maximize patient benefit and tolerability.”

"Lunresertib and Debio 0123 have the potential to be a transformative combination therapy for cancer patients with high unmet medical need,” said Angela Zubel, Chief Development Officer of Debiopharm. “Treating the first patient in this new Module of the MYTHIC clinical trial is an important milestone for our collaboration, as it allows us to execute clinical development swiftly. We look forward to working closely with Repare to further characterize these innovative precision medicine therapies.”