A phase I dose escalation study of sunitinib plus capecitabine in patients with advanced solid tumors

Abstract

3592 Background: Sunitinib malate (SU) is an oral, multitargeted tyrosine kinase inhibitor of VEGFRs, PDGFRs, KIT, RET, and FLT3, approved internationally for the treatment of advanced RCC and imatinib-resistant or -intolerant GIST. This phase I study assesses the safety, tolerability and pharmacokinetics (PK) of SU in combination with capecitabine (C). Methods: Pts with advanced solid tumors not amenable to curative therapy, previously treated with =2 prior chemotherapy regimens, and ECOG PS =1 were eligible. Prior antiangiogenic therapy was not permitted. Three SU schedules were evaluated: 4 wks on treatment followed by 2 wks off in 6-wk cycles (4/2 schedule); 2 wks on followed by 1 wk off in 3-wk cycles (2/1 schedule), and continuous dosing (CD schedule). In all cases C was administered orally bid on days 1–14. SU and C doses were alternately escalated in serial pt cohorts to determine the maximum tolerated dose (MTD) of SU for all schedules using a standard 3 + 3 design. PK and antitumor efficacy were also assessed. Results: A total of 50 pts have been enrolled; 28 pts have been treated on the 4/2 schedule: SU 50 mg + C 1,000 mg/m2, and SU 37.5 mg + C 1,250 mg/m2 were not tolerated. Dose limiting toxicities (DLTs) included: grade 3 myalgia (n=1), grade 3 fatigue (n=2), and grade 3 hand- foot syndrome (n=2). The MTD for the 4/2 schedule was SU 37.5 mg/day + C 1,000 mg/m2. No DLTs nor dose reductions were observed among 9 pts treated at the MTD. Preliminary PK data do not indicate drug-drug interactions between SU and C. 3 pts (1 each with breast cancer, neuroendocrine carcinoma, and thyroid carcinoma) achieved confirmed partial responses. On the 2/1 schedule patients are being accrued to SU 37.5 or 50 mg + C 1,000 mg/m2 and doses of SU 37.5 mg + C 1,000 mg/m2 or SU 25 mg + C 1,250 mg/m2 are being explored on the CD schedule. Conclusions: The combination of SU 37.5 mg/day (4/2 schedule) with C 1,000 mg/m2 in pts with advanced solid tumors appears tolerable. SU may be administered in combination with C with no apparent drug-drug interaction. Subsequent cohorts will define the MTD of SU administered on the 2/1 and CD schedules. Further studies of this combination in breast cancer are warranted. No significant financial relationships to disclose.