A first-in-human (FIH), phase 1/2, dose-escalation, dose-optimization, and dose-expansion study of PARP1-selective inhibitor IMP1734 in participants with advanced solid tumors.

TPS3191 Background: PARP inhibitors (PARPi) selectively kill tumor cells harboring genetic mutations in critical DNA repair genes (e.g., BRCA1/2). While several approved nonselective PARPi have provided robust anti-tumor activity, they are associated with significant hematologic toxicities that limit dose intensity and clinical benefit. Drugs that selectively inhibit PARP1 but spare PARP2 may improve the risk-benefit profile for this class of therapies by retaining anti-tumor activity while avoiding PARP2-related toxicities. IMP1734 (EIK1003) is a potent PARP1-selective inhibitor that inhibits tumor growth in nonclinical models and may widen the therapeutic index in tumors where non-selective PARPi have demonstrated efficacy. Methods: Study EIK1003-001 (IMP1734-101) is a global, multi-center, Phase 1/2 study evaluating the safety and potential antitumor activity of IMP1734 in participants with advanced solid tumors. The study has 3 parts: Part 1 (FIH; Dose Escalation), Part 2 (Dose Optimization), and Part 3 (Dose Expansion at the recommended dose for expansion RDE). Part 1 of this study is currently enrolling and consists of dose escalation of IMP1734 in study participants with advanced/recurrent/metastatic ovarian, breast, or prostate cancer with suspected deleterious/deleterious mutations in a pre-specified panel of homologous recombination repair (HRR) genes (n = 70). Eligible participants must be ≥ 18 years of age, have histologically or cytologically confirmed tumors as indicated in each study part, and at least 1 RECIST v1.1-measurable lesion and/or pre-specified serum tumor-specific marker. All participants must have a deleterious or suspected deleterious mutation in select HRR genes. Primary endpoints include safety and tolerability (evaluation of dose-limiting toxicities and determining the maximum tolerated dose, maximum achievable dose, and RDE). Secondary endpoints include evaluation of the pharmacokinetic parameters of IMP1734 and measures of efficacy, including overall response rate, duration of response, progression-free survival, and overall survival. Exploratory endpoints include analysis of pharmacodynamic biomarkers, serial ctDNA measurements, and patient quality-of-life measures. This study opened on 11 Dec 2023. Clinical trial information: NCT06253130 .