Repare Therapeutics' ATR Inhibitor Camonsertib Shows Promise in DNA Repair-Deficient Cancers
核心洞察
Camonsertib, a selective ATR inhibitor developed by Repare Therapeutics in partnership with Roche, demonstrated significant clinical activity in DNA damage response-deficient solid tumors (搜索) with results published in Nature Medicine.
The Phase 1/2 TRESR trial showed camonsertib combinations with PARP (搜索) inhibitors achieved a 48% clinical benefit rate across tumor types, with particularly compelling results in ovarian cancer (搜索) patients showing 32% overall response and 58% clinical benefit rate.
Early circulating tumor DNA molecular responses were observed in 66% of evaluable patients, confirming antitumor activity and providing mechanistic validation for the synthetic lethality approach in heavily pretreated patients.
Repare Therapeutics has achieved a significant milestone in precision oncology with the publication of promising clinical data for camonsertib (RP-3500/RG6526), a potent and selective oral ATR inhibitor developed in partnership with Roche. The results from the ongoing Phase 1/2 TRESR clinical trial, published in Nature Medicine, demonstrate the compound's potential in treating DNA damage response-deficient advanced solid tumors (搜索).
Clinical Trial Results Show Broad Antitumor Activity
The TRESR trial (NCT04497116), a first-in-human, multi-center, open-label Phase 1/2 dose-escalation and expansion study, evaluated camonsertib both as monotherapy and in combination with talazoparib or gemcitabine. The study was designed to establish the recommended Phase 2 dose and schedule while evaluating safety, pharmacokinetics, and preliminary anti-tumor activity.
"The results of the TRESR trial demonstrate not only the single agent activity of camonsertib, a potent and selective ATR inhibitor, but also define the importance of enhanced precision medicine approaches, such as the identification of bi-allelic alterations affecting the target DNA repair genes and other biomarkers," said Maria Koehler, MD, PhD, EVP and Chief Medical Officer of Repare.
Combination Therapy Shows Exceptional Promise
Additional data from the TRESR trial and the Phase 1b/2 ATTACC clinical trial (NCT04972110) revealed particularly encouraging results for camonsertib in combination with PARP (搜索) inhibitors. The ATTACC study evaluated camonsertib in combination with niraparib or olaparib in patients with advanced solid tumors (搜索).
Initial combination results from 107 patients, with 90 patients evaluable for efficacy, showed camonsertib combinations achieved a 48% clinical benefit rate across tumor types and different genomic alterations, regardless of the choice of PARP (搜索) inhibitor and presence of platinum resistance. Notably, patients with platinum-resistant tumors demonstrated an overall response rate of 12% and clinical benefit rate of 49%, performing similarly to non-platinum-resistant tumors.
Ovarian Cancer Results Particularly Compelling
The most striking results emerged in patients with advanced ovarian cancer (搜索), where 19 evaluable patients demonstrated a 32% overall response rate, 58% clinical benefit rate, and median progression-free survival of approximately 7 months. Treatment duration exceeded 16 weeks and remained ongoing in 9 patients at the time of data cutoff.
"We see promise in the camonsertib-PARPi combinations when administered concomitantly, at low doses across tumor types, especially in recurrent ovarian cancer (搜索) given that nearly all had recurred after prior PARPi treatment," noted Dr. Koehler. "We are particularly encouraged by the depth of response and duration of treatment."
Molecular Biomarkers Confirm Treatment Effect
The trials incorporated sophisticated biomarker analysis, including circulating tumor DNA (ctDNA) monitoring, which provided mechanistic validation of the treatment approach. Early ctDNA molecular responses were observed in 66% (31/47) of evaluable patients, confirming antitumor activity of the low-dose, intermittent PARP (搜索) inhibitor plus ATR inhibitor therapy.
The molecular response rate was significantly higher in patients with clinical benefit (83%) compared to those without (48%; p=0.015), confirming treatment effect. Importantly, molecular responses were observed even in patients with prior PARP (搜索) inhibitor exposure (57%) and platinum resistance (64%).
Safety Profile Supports Further Development
The safety profile of camonsertib combinations appeared favorable, with dose-limiting toxicities in 68 patients treated with proposed combination doses related primarily to myelotoxicity. Grade 3+ adverse events included anemia (3%), thrombocytopenia (6%), neutropenia (7%), and febrile neutropenia (3%). Notably, no prophylactic growth factors were required when administering the PARP (搜索) inhibitors at evaluated doses.
Precision Medicine Platform Drives Discovery
The success of camonsertib exemplifies Repare's SNIPRx® platform approach, which utilizes genome-wide CRISPR-based screening to identify synthetic lethal gene pairs. This proprietary platform enables the development of precision therapeutics targeting patients whose tumors contain specific genomic alterations identified through SNIPRx® screening.
"This study provides a framework for the testing of novel therapeutic approaches based on the principles of synthetic lethality and informed by genome-wide CRISPR screens," Dr. Koehler explained.
Lloyd M. Segal, President and Chief Executive Officer of Repare, emphasized the broader implications: "The circulating tumor DNA data showed a strong correlation with the degree of tumor shrinkage and duration of disease control, and provide a mechanistic explanation for the observed durable clinical benefit in heavily pretreated patients, beyond the natural history of the disease."
The company continues dose optimization efforts and efficacy assessment in tumor-specific expansions as part of its ongoing collaboration with Roche, with plans to refine the combinatorial dosing approach for additional tumor types beyond ovarian cancer (搜索).