On October 13, 2023 Repare Therapeutics Inc. ("Repare" or the "Company") (Nasdaq: RPTX), a leading clinical-stage precision oncology company, reported positive initial data from Modules 1 and 2 of its ongoing Phase 1 MYTHIC clinical trial evaluating lunresertib alone and in combination with camonsertib, an ATR inhibitor (Press release, Repare Therapeutics, OCT 13, 2023, View Source [SID1234635954]). The data are being presented in a plenary session titled, "New Drugs on the Horizon" at the AACR (Free AACR Whitepaper)-NCI-EORTC AACR-NCI-EORTC (Free AACR-NCI-EORTC Whitepaper) International Conference on Molecular Targets and Cancer Therapeutics (EORTC-NCI-AACR) (Free ASGCT Whitepaper) (Free EORTC-NCI-AACR Whitepaper), being held October 11-15, 2023 in Boston, Mass.
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Lunresertib (RP-6306) is a first-in-class precision oncology small molecule PKMYT1 inhibitor that targets CCNE1 amplification, FBXW7 and PPP2R1A alterations in solid tumors. Lunresertib is being evaluated alone and in combination with camonsertib (RP-3500 / RG6526), a potent and selective oral inhibitor of ATR developed by Repare and now partnered with Roche for development excluding the lunresertib + camonsertib combination.
"We’re excited by these first clinical proof-of concept results and believe that they further validate the pipeline power of our SNIPRx discovery platform and demonstrate the potential of lunresertib as the only clinical-stage PKMYT1 inhibitor," said Lloyd M. Segal, President and Chief Executive Officer of Repare. "We saw early efficacy signals across multiple tumor types and in each genotype selected, most notably in gynecological tumors where the lunresertib + camonsertib combination provides a potential new treatment option for these patients. Today is an important step forward in Repare’s mission to deliver next-generation precision oncology medicines to patients with genomically-defined tumor alterations predicted by our platform to respond to our candidate drugs."
"The data presented today, although early, are highly promising as lunresertib in combination with camonsertib results in clear clinical activity across several tumor types and genotypes along with a favorable safety and tolerability profile," said Dr. Timothy A. Yap, MBBS, PhD, FRCP, Professor in the Department of Investigational Cancer Therapies (Phase 1 Program) and Vice President, Head of Clinical Development in the Therapeutics Discovery Division at The University of Texas MD Anderson Cancer Center and Principal
Investigator on the MYTHIC trial. "These early data suggest treatment with lunresertib in combination with camonsertib could result in efficacy outcomes for patients in the gynecological cancer setting, an area where we’re still seeing unmet patient needs despite current therapies."
Key Initial Findings from the Phase 1 MYTHIC Clinical Trial:
MYTHIC (NCT: NCT04855656), a first-in-human, global, open-label Phase 1 dose-escalation clinical trial to evaluate safety, pharmacokinetics, pharmacodynamics and preliminary anti-tumor activity of lunresertib as a monotherapy (Module 1) or in combination with camonsertib (Module 2) in patients with advanced solid tumors harboring CCNE1 amplification or FBXW7 or PPP2R1A deleterious alterations achieved clinical proof of concept. As of September 5, 2023, the cutoff date for the data presented at the AACR (Free AACR Whitepaper)-NCI-EORTC conference, 67 patients were enrolled in Module 1 and 59 patients in Module 2.
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Protocol-defined overall response (OR) (RECIST or GCIG CA-125 responses) at the combination preliminary recommended phase 2 dose (RP2D) was 33.3% (N=18); CBR at the combination preliminary RP2D (overall response or stable disease of at least 16 weeks without tumor progression) was 50.0%. In all evaluable patients, across all doses (N-55), OR was 23.6% and CBR was 41.8%.
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In patients with gynecologic tumors at the combination preliminary RP2D (N=10), the RECIST response was 50%, OR 60%, and CBR 70%. Patients in this cohort had a median of 3 and up to 9 prior lines of therapy.
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RECIST responses in this ongoing combination trial included 8 confirmed and 3 unconfirmed partial responses (PR). Additionally, 3 patients with ovarian tumors had cancer antigen 125 (CA-125) responses.
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RECIST responses and clinical benefit with combination therapy was seen across all 3 lunresertib-sensitizing alterations: CCNE1 amplification or FBXW7 or PPP2R1A deleterious alterations. Molecular response rate (MRR) was significantly higher in combination compared to monotherapy (p=0.003), providing further evidence of enhanced anti-tumor activity: observed MRR in combination therapy was 50% (n=24), compared to 10% (n=30) with lunresertib monotherapy.
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Encouraging and highly manageable safety and tolerability was observed for the combination therapy (n=59). The most common treatment-related adverse event (TRAE) was anemia, with grade 3 occurring in 42% of patients:
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Anemia usually improved with a one-week treatment interruption and standard supportive care and did not lead to any therapy discontinuations at preliminary RP2D.
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There were no Grade 4 or Grade 5 TRAEs reported at preliminary RP2D.
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Data clearly indicates that anemia management can be individualized and alleviated with simple patient monitoring. This approach is now being tested in the MYTHIC trial.
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35% of patients did not develop anemia at preliminary RP2D. Generally, those with grade 3 anemia had the lowest hemoglobin values at entry, were intensely pretreated with >4 prior therapies and were of advanced age.
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Achieved the first clinical proof-of-concept for a synthetic lethal strategy with a PKMYT1 inhibitor combined with an ATR inhibitor in patients with molecularly-selected cancers.
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Patient enrollment in MYTHIC continues both to optimize the schedule for the combination and to further investigate the promising antitumor signals seen to date in a larger number of patients with selected tumors and genomic alterations.
"The encouraging Phase 1 safety and tolerability profile and early antitumor efficacy data provide proof of concept for lunresertib and clear direction for further development of the chemotherapy-free combination of lunresertib + camonsertib to selectively target the lunresertib-relevant alterations across multiple tumor types, including line of sight on later stage randomized or otherwise definitive studies as the data continue to mature," said Maria Koehler, MD, PhD, Chief Medical Officer of Repare. "This novel, orally delivered combination may provide new therapeutic options in areas of high unmet need, and we look forward to completing the multiple expansions of the Phase 1 MYTHIC study and reporting results in 2024 with later-stage trials expected to initiate shortly thereafter."
Company Virtual Webcast Event:
Repare will host a conference call and webcast today, October 13, 2023, at 5:30 p.m. Eastern Time to discuss the results presented at the AACR (Free AACR Whitepaper)-NCI-EORTC conference, including updated data since the September 5, 2023 data cutoff. Repare’s executive management team will be joined by Dr. Timothy A. Yap, MBBS, PhD, FRCP, Principal Investigator, Professor in the Department of Investigational Cancer Therapies (Phase 1 Program) and Vice President, Head of Clinical Development in the Therapeutics Discovery Division at the University of Texas MD Anderson Cancer Center in Houston, Texas.
To access the call, please dial (877) 870-4263 (U.S. and Canada) or (412) 317-0790 (international) at least 10 minutes prior to the start time and ask to be joined to the Repare Therapeutics call. A live webcast will be available in the Investor section of the Company’s website at View Source . A webcast replay will also be archived for at least 30 days.