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

LAUSANNE, Switzerland & MONTREAL–(BUSINESS WIRE)– 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, and Repare Therapeutics Inc. (“Repare”) (Nasdaq: RPTX), a leading clinical-stage precision oncology company, announced that the first patient has been dosed in Module 4 of the ongoing Phase 1/1b MYTHIC (NCT04855656) clinical trial, investigating the combination of Debio 0123 and lunresertib. 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, Debiopharm and Repare announced a collaboration to evaluate the clinical combination of Debio 0123, an oral, brain-penetrant, highly selective WEE1 kinase inhibitor and lunresertib, a first-in-class, selective and potent oral small molecule inhibitor of PKMYT1. 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.

“Debio 0123 and lunresertib 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.”

“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.”

About Debio 0123

Debio 0123 is an oral, brain-penetrant, highly selective WEE1 kinase inhibitor. WEE1 is a key regulator of the G2/M and S phase checkpoints, activated in response to DNA damage and replication stress, allowing cells to repair their DNA before resuming their cell cycle. WEE1 inhibition, particularly in combination with DNA damaging agents, induces an accumulation of DNA damage and pushes the cells through cell cycle without DNA repair, promoting mitotic catastrophe and induction of apoptosis in cancer cells. Debio 0123 is currently being investigated in clinical trials in patients with solid tumors as a monotherapy and in combination. Debio 0123 is being developed to address high unmet needs of patients living with the burden of difficult-to-treat cancers.

About Lunresertib

Lunresertib (RP-6306) is a first-in-class, selective and potent oral small molecule inhibitor of PKMYT1, a cancer target Repare discovered and identified as synthetic lethal with CCNE1 amplification, FBXW7 and PPP2R1A alterations in solid tumors. Lunresertib is currently the sole PKMYT1 inhibitor known to be in clinical trials and is being evaluated alone and in combinations across several studies in the US, UK/EU4 and Canada. Repare has presented positive initial Phase 1 data from its ongoing Phase 1 MYTHIC trial (NCT04855656) demonstrating proof of concept for lunresertib alone and in combination. In addition to being well tolerated and having a compelling safety profile, Repare presented anti-tumor activity for lunresertib in combination with camonsertib, an ATR inhibitor developed by Repare, expanded clinical studies for which are ongoing.

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 lunresertib (also known as RP-6306), a PKMYT1 inhibitor currently in Phase 1/2 clinical development; camonsertib (also known as RP-3500), a potential leading ATR inhibitor currently in Phase 1/2 clinical development; RP-1664, a Phase 1 PLK4 inhibitor program; RP-3467, a preclinical Polθ ATPase inhibitor program; as well as additional, undisclosed preclinical programs. For more information, please visit reparerx.com and follow @Reparerx on X (formerly Twitter) and LinkedIn.

Debiopharm’s Commitment to Patients

Debiopharm aims to develop innovative therapies that target high unmet medical needs in oncology and bacterial infections. Bridging the gap between disruptive discovery products and real-world patient reach, we identify high-potential compounds and technologies for in-licensing, clinically demonstrate their safety and efficacy, and then hand stewardship to large pharmaceutical commercialization partners to maximize patient access globally.

For more information, please visit www.debiopharm.com

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Contacts

Debiopharm
Dawn Bonine

Head of Communications

dawn.bonine@debiopharm.com
Tel: +41 (0)21 321 01 11