A phase I/II trial of sorafenib (S) with bevacizumab (B) in metastatic renal cell cancer (mRCC) patients (Pts)

Abstract

3031 Background: In an effort to enhance the efficacy of vascular endothelial growth factor (VEGF) pathway blockade in mRCC we initiated a Phase I-II trial of combination S and B to block VEGFR signaling and VEGF binding, as well as, platelet derived growth factor receptor β (PDGFR) signaling. Methods: Pts with measurable (RECIST) mRCC, adequate organ function, and PS 0–1 were eligible for this trial. Cohorts of 6 pts were enrolled at 3 sites to define the MTD and DLT of the combination of S and B. The schedule was B IV q 14 days and S daily with cycles of 28 days. Response and toxicity were assessed at the end of 2 cycles. Dose levels began with S at 200mg BID and B at 5 mg/kg (level 1) with the hope to reach phase II doses of both agents (S at 400mg BID and B at 10mg/kg). The MTD or the phase II dose of each agent would then be administered to up to 45 pts with mRCC, clear cell histology, and prior nephrectomy. Results: A total of 18 patients have been enrolled to date, with 15 completing their first response evaluation. Pts were median age 61 years (46–74 range); M/F: 15/3; PS: 0/1= 12/6; 17 clear cell, 1 chromophobe, 11 prior nephrectomy; 4 with prior cytokine therapy. Two pts in level 1 experienced DLT with recurrent and intolerable (grade 3) hand-foot syndrome (HFS). An additional 6 patients were treated at dose level -1 (S at 200mmg QD and B at 3mg/kg) with no DLTs. Six more pts have been treated at dose level 1 with Vit B6 at 300mg/d in an attempt to minimize HFS. Toxicity data in this cohort is incomplete. Additional toxicities among the 18 pts included grade 3 hypertension (4), grade 3 proteinuria (2), and grade 2 stomatitis (3). Responses including 4 objective PRs, and 4 pts with 20–30% regression have been seen in the 14 evaluated pts. Only 2 patients have had disease progression. Conclusions: The phase II doses for this combination have not yet been established, but will likely be lower than the full phase II doses of the individual agents. The toxicities from HFS (primarily) and hypertension and stomatitis appear to be limiting. Even at the initial low doses of S and B, significant anti-tumor activity has been observed. The completion of this phase I trial will be reported. The phase II studies in mRCC are highly anticipated. Support by phase I contract UO-1 CA099177 [Table: see text]