Neoadjuvant Cisplatin, Gemcitabine, and Docetaxel in Sarcomatoid Bladder Cancer – Clinical Activity and Whole Transcriptome Analysis

Background: Sarcomatoid urothelial cancer of the bladder (SBC) is a rare, but aggressive histological subtype for which novel treatments are needed. Objective: We evaluated the clinical activity and safety of neoadjuvant cisplatin plus gemcitabine plus docetaxel (CGD) in muscle-invasive patients with SBC and assessed SBC tumor biology by whole transcriptome RNA sequencing. Methods: A single-institution, retrospective analysis of muscle-invasive SBC patients treated with neoadjuvant CGD with molecular analysis. Patients received cisplatin 35 mg/m2 + gemcitabine 800 mg/m2 + docetaxel 35 mg/m2 intravenously on days 1 and 8 + pegfilgrastim 6 mg subcutaneously on day 9 every 3 weeks for 4 cycles followed by cystectomy. The primary endpoint was pathologic complete response (ypCR) rate. Results: Sixteen patients with SBC received neoadjuvant CGD with a ypCR rate of 38% and a < ypT2 rate of 50%. Grade 3 and 4 toxicity occurred in 80% and 40% of patients, but was manageable with 81% of patients completing > 3 CGD cycles. Whole transcriptome RNA sequencing demonstrates co-clustering of SBC with conventional urothelial tumors. SBC tumors are characterized by basal-squamous and stroma rich gene signatures with frequent increased expression of immune checkpoint (CD274 (PD-L1)), chemokine (CXCL9), and T-cell (CD8A) genes. Conclusions: SBC is a chemosensitive subtype, with ypCR rate similar to urothelial bladder cancer following CGD neoadjuvant therapy. Whole transcriptome tissue analyses demonstrate increased expression of immune checkpoint and T-cell genes with therapeutic implications.