Background: Lucitanib is an oral, potent tyrosine kinase inhibitor that selectively inhibits VEGFR1–3, PDGFRα/β, and FGFR1–3. In preclinical studies, antitumor activity of rucaparib is enhanced by lucitanib through antiproliferative, antiangiogenic, and immunological mechanisms. We hypothesize that combining lucitanib and rucaparib is tolerable and can induce a higher hypoxic state and homologous recombination repair deficiency that may lead to greater sensitivity to PARP inhibition. Methods: Patients with advanced solid tumors who had ≥1 prior line of therapy were eligible. Patients with BRCA1/2-mutated ovarian cancer must have received prior PARP inhibitor. Rucaparib and lucitanib were escalated using a 3+3 phase 1b dose-escalation design from starting doses of 300 mg BID and 4 mg QD, respectively. Dose-limiting toxicities (DLTs) were assessed during the first 28 days of treatment. Plasma samples were collected for pharmacokinetic analyses. Genomic alterations were identified by local testing, or through central testing of plasma or tumor tissue. Results: As of February 1, 2021, 16 patients were treated with rucaparib + lucitanib and included in the analyses (Table). Patients had a median of 4 prior therapies; 1 patient had prior PARP inhibitor (olaparib) treatment. Median time on treatment was 58.5 days, with 2 patients ongoing as of the data cutoff date. A DLT of grade 3 proteinuria was seen in Cohort 1; no other DLTs have been reported. Across all cohorts, the most common any-grade treatment-emergent adverse events were nausea (n=9; grade ≥3, n=1), hypertension (n=8; grade ≥3, n=2) and ALT/AST increased (n=7; grade ≥3, n=3). Initial pharmacokinetic data indicated no drug interactions between the 2 agents. To date, 1 patient in Cohort 1 with PALB2-mutated advanced endometrial cancer had a confirmed partial response per RECIST v1.1, lasting 30 weeks; 6 patients had RECIST v1.1 stable disease (SD), including 1 patient each in Cohorts 1 and 3 with SD for ≥16 weeks. In addition, 1 patient in Cohort 2 with BRCA2-mutated castration-resistant prostate cancer continued to receive treatment despite initial progressing bone metastases, resulting in a prostate-specific antigen response (≥50% change) lasting 16 weeks and a best change in sum of target lesions of −46.3%. Conclusions: Initial findings suggest that rucaparib + lucitanib has an acceptable safety profile. The safety and efficacy of the combination are being further evaluated. Clinical trial information: NCT03992131

*Based on local testing results only. BID, twice daily; QD, daily; HRR, homologous recombination repair.