Neoadjuvant sorafenib, gemcitabine, and cisplatin (SGC) for muscle-invasive urothelial bladder cancer (MIUBC): Final results and translational findings of an open-label, single-arm, phase II study

345 Background: Despite cisplatin-based chemotherapy (CT) is recommended in MIUBC, an unmet need is to identify new drugs or combinations to improve the outcomes. SGC combination was evaluated in an open-label, single-arm, phase 2 trial (NCT01222676). Methods: After TURB, pts with T2-T4a N0 MIUBC received 4 cycles of cisplatin 70 mg/m2 d1, gemcitabine 1000 mg/m2d1 and 8, q3 wks. Sorafenib 400 mg q12h was administered daily from day 1 until radical cystectomy. In a Simon’s 2-stage design, the primary endpoint was pathologic complete responses (pT0). Residual carcinoma in situ was considered pT0. ITT analysis was applied. Statistical hypothesis assumed H0: ≤0.20 and H1: ≥0.40 (α and β of 5% and 10%). ERCC1 immunohistochemistry (IHC) and next-generation sequencing (NGS) of TURB tissue, and measurement of baseline circulating VEGF levels, were planned. Results: From 04/2011-06/2016, 45 pts were enrolled. 28 pts (62.2%) had macroscopical residual disease after TURB, 17 (37.8%) presented with clinical stage T3-4. pT0 was obtained in 19 pts (42.2%, 95%CI: 27.6-57.9); pT≤1 in 24 (53.3%, 95%CI: 37.9-68.3). After median follow-up of 35 months, median PFS was not reached (IQR: 29.4-NE), like median OS (IQR: 30.3-NE). Pathological response (pT0 vs pT≤1 vs other) predicted for both PFS (p=0.015) and OS (p=0.046). Hematologic (hem) G3-4 adverse events (AE): platelet 28.9%, neutrophils 15.6%, Hb (4.4%). Extra-hem AEs were seen in 9 pts (20%). 24 (53.3%) pts needed S temporary interruption (5 cases discontinuation). Tumor samples were available from 23 pts for ERCC1-IHC, 24 for NGS: ERCC1 IHC expression was associated with non response (pT≥2, p=0.033). ERBB2/ERBB3 mutations were found only in responders (pT≤1, 20%). PIK3CA/AKTmutations (missense, and newly-identified mutations) were more frequent in pT≥2 pts (35.7% vs 20%). Baseline VEGF levels did not predict for PFS/OS. NGS of the remaining pts of the trial is ongoing. Conclusions: SGC combination was active and effective in MIUBC. Translational analyses are providing information to develop combination of CT with new more potent and selective TKIs, possibly in more selected pts. Clinical trial information: NCT01222676.