Olaparib combined to metronomic cyclophosphamide and metformin in women with recurrent advanced/metastatic endometrial cancer: the ENDOLA phase I/II trial

Endometrial cancers are characterized by frequent alterations in the PI3K-AKT-mTor, IGF1 and DNA repair signaling pathways. Concomitant inhibition of these pathways was warranted. ENDOLA phase I/II trial (NCT02755844) was designed to assess the safety/efficacy of the triplet combination of the PARP inhibitor olaparib, metronomic cyclophosphamide (50 mg daily), and PI3K-AKT-mTor inhibitor metformin (1500 mg daily) in women with recurrent endometrial carcinomas. Olaparib dose-escalation (100-300 mg twice-a-day (bid)) was used to determine the recommended-phase II-trial-dose (RP2D, primary endpoint), followed by an expansion cohort to determine the non-progression rate at 10 weeks (NPR-10w, secondary endpoint). 31 patients were treated. Olaparib RP2D was defined as 300 mg bid. The tolerability was acceptable, and grade 3-4 adverse events (51% patients) were mainly hematological. The NPR-10w was 61.5%, and the median progression-free survival (mPFS) was 5.2 months. In a post-hoc analysis, when explored by molecular subtypes/alterations, longer PFS were observed in patients with tumors characterized by a non-specific-molecular-profile (NSMP, n = 4; mPFS, 9.1 months), and by both TP53 altered & high number of large genomic alterations (LGA ≥ 8)(n = 10, mPFS, 8.6 months)). The analyses about kinetics of circulating biomarkers and pharmacodynamic effects are not reported here. In total, the benefit/toxicity ratio of the all-oral olaparib/cyclophosphamide/metformin regimen was favorable in heavily pretreated patients with recurrent endometrial cancer.