SWOG S1314: A randomized phase II study of co-expression extrapolation (COXEN) with neoadjuvant chemotherapy for localized, muscle-invasive bladder cancer with overall survival follow up.

Abstract

536 Background: This trial evaluated COXEN, a gene expression model, as a predictive biomarker in muscle-invasive bladder cancer (BC) patients randomized to Gemcitabine-Cisplatin (GC) or dose-dense Methotrexate-Vinblastine-Adriamycin/doxorubicin-Cisplatin (ddMVAC). Primary results correlating COXEN with pathologic response at surgery have been reported. This secondary analysis includes progression-free (PFS) and overall survival (OS). Methods: Eligibility included Stage cT2-T4a N0 M0, urothelial BC (mixed histology allowed), ≥ 5 mm of viable tumor, cisplatin eligible, with plan for cystectomy. 237 patients were randomized between ddMVAC, given every 14 days for 4 cycles, and GC, given every 21 days for 4 cycles. Cox regression was used to evaluate COXEN score or treatment arm association with PFS and OS, adjusting for stratification factors (stage and PS). Results: 167 patients were included in the primary COXEN analysis all having either at least 3 cycles of chemo and surgery within 100 days of last chemo or having progressed while receiving chemo. The COXEN scores were not significantly prognostic for OS or PFS in their respective arms; the COXEN GC score was a significant predictor for OS in pooled arms. OS and PFS data are shown for both scores in the table. In the intent to treat analysis (n=227), there was no significant difference in OS or PFS for ddMVAC versus GC (for OS, HR =0.87, 95% CI 0.54-1.40), p = 0.57); for PFS (HR= 0.76 95% CI 0.58-1.01, p = 0.055). Association of path response with OS will be presented. Conclusions: The COXEN GC score may be prognostic of survival in those receiving platinum-based neoadjuvant treatment. The randomized, prospective design provides estimates of OS and PFS for GC and ddMVAC that appear comparable, but this phase II trial is underpowered for definitive comparisons. The prospective data and correlative samples from S1314 will allow for further assessment of COXEN and other RNA and DNA based predictive and prognostic biomarkers. Clinical trial information: NCT02177695. [Table: see text]