A phase II trial of durvalumab (Medi 4736) in advanced endometrial cancer: PHAEDRA.

Abstract

TPS5614 Background: Advanced endometrial cancer (EC) progressing after 1 or more lines of chemotherapy is an area of unmet need with objective tumour response rates to subsequent lines of chemotherapy of ≤20%. DNA mismatch repair (MMR) deficiency, seen in approximately 15% of EC, is associated with a high mutational load and in addition, up to 90% of ECs are reported to have PDL1/ PD1 expressions. These factors make immune check point inhibition an ideal target for treatment. Methods: DESIGN: Multicentre phase 2 trial in two cohorts. ELIGIBILITY: Advanced, unresectable endometrial cancer that is either MMR-proficient and progressing after 1-3 lines of chemotherapy, or MMR-deficient and progressing after 0-3 lines of chemotherapy. ENDPOINTS: Objective tumour response rate (OTRR) according to iRECIST (primary) and RECIST 1.1, disease control rates at 16 and 24 weeks, progression free survival, overall survival, duration of OTR and DC, adverse events, health related quality of life. Tertiary correlative objectives: Associations between immunologic (including PD-L1), DNA mismatch repair (MMR) and other genetic characteristics with clinical outcomes; and family history of cancer and referral to familial cancer services. INTERVENTION: Durvalumab 1500 mg intravenously every 28 days until disease progression or prohibitive toxicity. STATISTICS: Total of 70 participants in two cohorts (35 each) will have 90% power to distinguish a difference in observed OTRR of ≥20% versus ≤5% (uninteresting rate) using Simon’s 2-stage minimax design with 10% type 1 error rate and allowing 10% ineligibility and missing data. Durvalumab will be considered worthy of pursuit if 4 or more OTR are observed in the first 32 participants in each cohort (OTRR ≥12.5%). BIOSPECIMENS: Tumour tissue and serial bloods (5 time points) will be collected for translational research. PHAEDRA is an investigator-initiated, cooperative-group trial led by ANZGOG, in collaboration with NHMRC Clinical Trials Centre, University of Sydney. Australian New Zealand Clinical Trials Registry: Clinical trial information: ACTRN12617000106336.