Concurrent durvalumab and radiation therapy followed by adjuvant durvalumab in patients with locally advanced urothelial cancer of bladder (DUART): Btcrc-GU15-023.

Abstract

513 Background: Bladder cancer (BC) patients (pts) who are cisplatin ineligible/unfit for surgery, unresectable have limited treatment options. In this study, we investigate if the combination of radiation therapy (RT) and checkpoint inhibitor, durvalumab (durva) is safe and effective in these pts. Our results from phase (ph) Ib suggested that the combination was safe. Here we present the response rate post durvaRT and updated treatment related adverse events (TRAEs) amongst our evaluable pts in ph II. Methods: This is a single arm ph Ib-II study for T2-4 N0-2 M0 pts. The ph II primary endpoints a) PFS rate at 1 yr b) disease control rate (DCR); secondary endpoints were a) CR post durvaRT b) PFS c) OS. Pts were treated with durva (1500mg) Q4 wks x2 doses along with definitive RT (64.8Gy, 36 fractions over 7 wks) to the bladder and involved nodes followed by adjuvant durva Q4 wks x 1 yr. Response was evaluated with CT scan and cystoscopy+biopsy post durvaRT. We anticipated that durvaRT followed by durva would increase PFS at 1 yr from 50% to 75% when compared to RT; we assumed DCR of about 75%. A total of 26 pts were needed to reach a statistical power of at least 80% at one-sided alpha of 5% and to allow for 10% drop out rate. Results: Total N = 26 patients (male 19; female 7, median age 74yr). At the time of data cut off, 21/26 pts were evaluable for response post durvaRT. Post completion of durvaRT time point, clinical CR was seen in 15/21 pts (71.4%); PR 1/21 pts (4.7%); SD 4/21 (19%); PD 1/21 (4.7%). DCR was seen in 20/21 pts (95%) post durvaRT. Median follow up from D1 to last follow up was 6.1 mos. Grade ≥ 3 TRAE amongst 26 pts: anemia (1/26), lipase/amylase (1/26), immune nephritis (1/26), dyspnea (gr 4, copd/immune), fatigue (1/26), lymphopenia (6/26). Other TRAEs: Fatigue was the most common TRAE (16/26); UTI (5/26); cystitis (3/26). No fatal TRAEs were observed. Conclusions: DurvaRT demonstrated promising efficacy with clinical CR of 71.4% and DCR of 95% in unresectable, cisplatin ineligible locally advanced BC. It was generally well tolerated. Ph II study has completed accrual and longer-term results will further our understanding of this regimen’s efficacy in locally advanced BC. Clinical trial information: NCT02891161.