Therapy for chemopretreated metastatic urothelial cancer (mUC) with the antibody-drug conjugate (ADC) sacituzumab govitecan (IMMU-132).

327Background: Patients (pts) with mUC pre-treated with platinum-containing chemotherapy have limited therapeutic options, with checkpoint-inhibitor immunotherapy (IO) responses in a minority of pts. We present an interim update of the safety and activity of sacituzumab govitecan (IMMU-132), an anti-Trop-2-SN-38 ADC, as therapy for chemotherapy-pretreated mUC pts (ClinicalTrials.gov, NCT01631552). Methods: We enrolled 32 pts with mUC and ECOG PS 0-1 who failed ≥ 1 prior standard therapy (median=3; range, 1-5). IMMU-132 was administered at 8 or 10 mg/kg on days 1 and 8 every 21 days, continued until disease progression (PD) or unacceptable toxicity. Response-evaluable pts received ≥ 2 doses, and had ≥ 1 post-baseline response assessment. Results: Twenty-five pts [median age 68 yrs (range: 50-91), 24 males] are currently assessable for safety and response; 23 had prior platinum-containing therapy; 46% had >2 prior therapies; 4 also had IO agents. Sites of metastases included liver (N=4; 16%), lungs (N=7; 28...