450 Background: FGFR3 mutations appear to be enriched in luminal 1 UC, which have low expression of markers associated with an immune response, including CD8-T-effector gene expression levels. Objective response rate (ORR) to PD-1 and PD-L1 inhibitors in luminal 1 tumors appear lower (10-19%) than in infiltrated luminal 2 and basal 3 tumors (ORR 31-34%). This suggests FGFR3 mutations occur within a group of tumors less likely to benefit from immune checkpoint inhibition (ICI). Here we describe outcomes of a subgroup of pts with FGFR2/3 mutations and gene fusions, previously treated with PD-1/PD-L1 inhibitors and included in an ongoing erdafitinib phase 2 study. Methods: Patients who had received prior immunotherapy for advanced UC were selected from those enrolled on BLC2001, an ongoing phase 2, open-label study of the pan-FGFR inhibitor erdafitinib in subjects with advanced UC with specific FGFR2/3 gene alterations (NCT02365597). We explored investigator-reported clinical outcomes including ORR and median time to progression (TTP) of pts treated with ICI preceding erdafitinib therapy. Results: 28/203 pts had previously received anti PD-1 or anti PD-L1 treatment. In this subgroup, the median age was 67.0 y; 82% were male, 79% had an ECOG score ≤1, 36% had liver metastases, and 93% had ≥2 prior lines of systemic therapy. The response rate to anti PD-1/PD-L1 agents was 3.6% (95% CI, 0.1%-18.3%) with one partial response. Median TTP was 3.4 mo (range 2-15 mo; 95% CI, 2.3-4.9). Conclusions: In this post-hoc analysis, FGFR mutations and gene fusions seem to select for a group of pts less likely to respond to immune checkpoint inhibition. Although caution is needed due to the retrospective nature of the data, the presence of these alterations may reflect an unmet need with currently approved agents. This finding highlights the need for FGFR alteration testing and an effective FGFR-targeted therapy. Clinical trial information: NCT02365597.
Efficacy and safety results from CheckMate 140, a phase 2 study of nivolumab for relapsed/refractory follicular lymphoma