A Phase 1 Trial of Durvalumab in Combination with Bacillus Calmette-Guerin (BCG) or External Beam Radiation Therapy in Patients with BCG-unresponsive Non-muscle-Invasive Bladder Cancer: The Hoosier Cancer Research Network GU16-243 ADAPT-BLADDER Study

Intravenous anti–PD-L1 durvalumab therapy can safely be combined with intravesical bacillus Calmette-Guerin (BCG) treatments or a short-course of bladder-focused external beam radiation therapy (6 Gy × 3) in BCG-unresponsive non–muscle-invasive bladder cancer patients. Encouraging preliminary efficacy requires validation. Novel treatments and trial designs remain a high priority for bacillus Calmette-Guerin (BCG)-unresponsive non–muscle-invasive bladder cancer (NMIBC) patients. To evaluate the safety and preliminary efficacy of anti–PD-L1 directed therapy with durvalumab (D), durvalumab plus BCG (D + BCG), and durvalumab plus external beam radiation therapy (D + EBRT). A multicenter phase 1 trial was conducted at community and academic sites. Patients received 1120 mg of D intravenously every 3 wk for eight cycles. D + BCG patients also received full-dose intravesical BCG weekly for 6 wk with BCG maintenance recommended. D + EBRT patients received concurrent EBRT (6 Gy × 3 in cycle 1 only). Post-treatment cystoscopy and urine cytology were performed at 3 and 6 –mo, with bladder biopsies required at the 6-mo evaluation. The recommended phase 2 dose (RP2D) for each regimen was the primary endpoint. Secondary endpoints included toxicity profiles and complete response (CR) rates. Twenty-eight patients were treated in the D (n = 3), D + BCG (n = 13), and D + EBRT (n = 12) cohorts. Full-dose D, full-dose BCG, and 6 Gy fractions × 3 were determined as the RP2Ds. One patient (4%) experienced a grade 3 dose limiting toxicity event of autoimmune hepatitis. The 3-mo CR occurred in 64% of all patients and in 33%, 85%, and 50% within the D, D + BCG, and D + EBRT cohorts, respectively. Twelve-month CRs were achieved in 46% of all patients and in 73% of D + BCG and 33% of D + EBRT patients. D combined with intravesical BCG or EBRT proved feasible and safe in BCG-unresponsive NMIBC patients. Encouraging preliminary efficacy justifies further study of combination therapy approaches. Durvalumab combination therapy can be safely administered to non–muscle-invasive bladder cancer patients with the goal of increasing durable response rates.