Comparison of cisplatin/gemcitabine or carboplatin/gemcitabine on efficacy, toxicity, and quality of life from the randomized DISCUS trial.

4583 Background: The DISCUS trial compared 3 versus 6 cycles (3C versus 6C) of chemotherapy followed by avelumab in 267 patients receiving first-line treatment for metastatic urothelial cancer. It showed 3 cycles of chemotherapy followed by maintenance avelumab was associated with better QoL than six cycles (NCT06892860). Efficacy outcomes of the two arms appeared similar. Here we compare the cisplatin (cis) or carboplatin (carbo) chemotherapy subsets in the 3C and 6C arms. Methods: Patients were randomized to receive either 3 or 6 cycles of chemotherapy. Cisplatin or carboplatin was allocated by physician choice. Progression free survival (PFS), Overall survival (OS), response rates, patient-reported outcomes (PROs) and treatment related adverse events were collected (TRAEs) were collected. The analysis was exploratory and p values nominal. Results: 267 were included of whom 55 received 3C/cis, 55 6C/cis, 78 3C/carbo and 79 6C/carbo. Patients receiving carboplatin had poor performance status (ECOG >=1 in 17% cis vs 35% carbo). Table 1 showed similar efficacy outcomes with potentially marginally superior OS with cisplatin. The comparison of efficacy and QOL endpoints for 3 vs 6 cycles of carboplatin showed many similarities. Six cycles of cisplatin-based chemotherapy was associated with a major drop in QOL compared to 3 cycles without showing any clear benefits in efficacy endpoints. Conclusions: The QoL benefits of shorter chemotherapy appear to be more marked in patients receiving cisplatin than carboplatin. The efficacy results for 3 cycles of cisplatin were impressive. This study was not powered for non-inferiority. Clinical trial information: NCT06892860 . Outcomes by treatment arm. 3C/cis (n=56) 3C/carbo (n=77) 6C/cis (n=54) 6C/carbo(n=80) CR (%) 16% 10% 14% 12% PFS (months), median(95% CI) 8.8(6.5-12.8) 8.0(5.8-12.0) 8.7(6.4-18.9) 9.0(6.6-13.1) OS (months), median(95% CI) Not reached(12.8-.) 18.5(12.6-.) 21.9(10.5-.) 15.0(9.8-.) G3 and above TRAE (n) 32 40 49 79 PRO (change from baseline to C7D1) 2.96 -2.51 -13.44 -4.86