Association of immune gene expression profiling with vinflunine clinical benefit in metastatic urothelial cancer (mUC).

Abstract

e16034 Background: There are limited treatment options for mUC after platinum-based chemotherapy failure. Immune checkpoint inhibitors (ICI) have shown a durable benefit but only in a minority of patients (20-25%). Vinflunine remains as a therapeutic option without validated biomarkers. In this study, we sought to analyze the molecular determinants of vinflunine response in mUC. Methods: mUC patients from 4 University Hospitals in Spain who received second-line vinflunine after platinum-based chemotherapy were classified in non-responders (NR: progressive disease ≤3 months; N = 10) or responders (R: response ≥ 6 months, N = 14). Targeted- sequencing of 275 cancer-related genes and a PanCancer Immune Profiling Panel were performed on pre-treatment tumors. Selected genes were evaluated by RT-qPCR and protein expression was detected by immunohistochemistry. Results: The most common alteration, TP53 mutations, had a similar frequency in R (7/14, 50%) and NR (4/10, 40%). Mutations in 5 genes: ERBB3 (4/14; 28,6%), KTM2C (4/14; 28,6%), PI3KCA (4/14; 28,6%), ARID2 (3/14; 21,4%) and FGFR3 (3/14; 21,4%) were identified only in R. Mutations in ERBB4 (3/10, 33,3%) and BCOR (2/10, 20%) were identified only in NR. Estimated TMBs were not significantly different among the R (13 per Mb) and NR (9 per Mb) samples. According to gene expression profiling, NR had high cytotoxic cells infiltrate and T cells as well as high counts of TILs compared to R. In addition, expression of IDO, MAGE A4, and SOCS1, that has been associated with response to ICIs, were down-regulated in R compared with NR. Conclusions: Gene profiling showed that low-expression levels of immune-related genes are significantly associated with clinical benefit from vinflunine. Validation and complementary studies are ongoing in patients treated with ICIs.