EIK1003 (PARP1-selective inhibitor) + weekly paclitaxel shows 23% ORR with manageable myelosuppression in platinum-resistant OC/HER2(–) BC

EIK1003 is a potent PARP1-selective inhibitor designed to reduce PARP2-linked myelosuppression seen with “classical” PARP1/2 inhibitors and potentially enable combination with cytotoxic chemotherapy. In the EIK1003-001 Phase 1/2 dose-escalation study (NCT06253130), EIK1003 QD (DL1–4) plus paclitaxel 80mg/m² weekly (days 1/8/15 q21d) in platinum-resistant recurrent ovarian cancer and HER2(–) breast cancer treated 51 patients (39 efficacy-evaluable); 62% had ≥4 prior lines, with 1 DLT (febrile neutropenia at DL4), grade ≥3 TEAEs in 62.7% (notably neutropenia 43.1%, anemia 15.7%), discontinuations in 8/51, and ORR 23.1% (1 CR, 8 PR) with DCR 74.4% and median DOR 6.4+ months—numerically in the ballpark of historical weekly paclitaxel activity in platinum-resistant ovarian cancer (often ~10–20% ORR reported across studies, with broader real-world ranges). In the monotherapy cohort (10–160mg QD), 65 patients were treated (49 efficacy-evaluable) with grade ≥3 TEAEs 43.1% (anemia 9.2%, neutropenia 7.7%), ORR 14.3% overall and 31.3% in PARP-naïve patients (5/16), and median DOR 6.2+ months.