Response to salvage chemotherapy after progression on immune checkpoint inhibitors in patients with advanced urothelial carcinoma.

Abstract

519 Background: Immune checkpoint inhibitors (ICI) are active in patients with advanced urothelial carcinoma which progressed to platinum-based chemotherapy. Recent data suggest that exposure to ICI improves response to salvage chemotherapy (SCT) in several cancer types. Here we evaluated whether PD-1/PD-L1 inhibitors affect the antitumor effects of SCT after ICI in patients with urothelial carcinoma. Methods: A retrospective study was conducted at Yonsei Cancer Center. Eligibility criteria were patients who received at least one SCT as 3rd-line or beyond, following progression after platinum-based chemotherapy and ICI and for whom efficacy data were available between January 2017 and September 2019. We evaluated efficacy outcomes to each therapy, including ORR by RECIST version 1.1, progression-free survival (PFS), and overall survival (OS). Results: In total, 35 patients met the inclusion criteria and were included in the analyses. ICIs were given as monotherapy and they were administrated as second-line in 48% and as later line in 52%. Twenty-six patients (74%) received a anti-PD-L1 inhibitor and 9 (26%) did a anti-PD-1 inhibitor. SCT included single paclitaxel (60%), MVAC (26%), gemcitabine/platinum combination (9%), and pemetrexed (6%). The ORR to SCT was 26%. Among 9 patients who received MVAC, 5 (55.5%) achieved a partial response. Median progression-free survival was 2.5 months and median overall survival was 7.8 months. A number of prior chemotherapy regimens was associated with response to SCT on univariate analysis. Conclusions: In urothelial cancer patients, the confirmed ORR (26%) to SCT after ICI exposure was higher as compared to historical data from the pre-ICI era. These data indicate that anti–PD-1/PD-L1 inhibitors could make tumors more vulnerable to subsequent chemotherapy.