Maintenance olaparib after platinum-based chemotherapy for advanced/metastatic endometrial cancer: GINECO randomized phase IIb UTOLA trial

Single-agent maintenance poly(ADP-ribose) polymerase (PARP) inhibition may represent an effective strategy in patients with advanced/metastatic endometrial cancer responding to platinum-based chemotherapy, including for molecular subtypes with suboptimal options. To explore this approach, we initiated the randomized phase IIb UTOLA trial (NCT03745950). Female patients without progression following front-line platinum-based chemotherapy for advanced/metastatic endometrial cancer were randomized 2:1 to twice-daily maintenance oral olaparib 300 mg or placebo until progression or intolerance, stratified by p53 status, mismatch repair status, and response to initial chemotherapy. The primary endpoint was progression-free survival (PFS) in the intention-to-treat population. Secondary endpoints were PFS in subgroups, time to second progression or death, time to first and second subsequent therapy, objective response rate, overall survival, patient-reported outcomes, and safety. In the intention-to-treat population (n = 145), there was no PFS difference between olaparib and placebo (median 5.6 vs. 4.0 months, respectively; hazard ratio 0.94, 95% confidence interval 0.65–1.35; p = 0.74). However, intriguing numerical PFS effects were observed in exploratory analyses of pre-specified subgroups (p53-abnormal, complete response to initial chemotherapy, chromosomal instability). There was no overall survival difference between treatments. Grade 3/4 adverse events occurred in 36% versus 10% of olaparib- versus placebo-treated patients and were consistent with the olaparib safety profile in other cancers. Maintenance olaparib did not improve PFS, but promising numerical effects in subsets of patients warrant prospective evaluation.