A Phase I Study to Investigate the Safety, Tolerability and Pharmacokinetics of Napabucasin Combined with Sorafenib in Japanese Patients with Unresectable Hepatocellular Carcinoma.

Background and objective: For patients with advanced hepatocellular carcinoma (HCC), the standard of care for many years has been sorafenib. Preliminary data have suggested that the combination of the NAD(P)H:quinone oxidoreductase 1 bioactivatable agent napabucasin plus sorafenib may improve clinical outcomes in patients with HCC. In this phase I, multicenter, uncontrolled, open-label study, we evaluated napabucasin (480 mg/day) plus sorafenib (800 mg/day) in Japanese patients with unresectable HCC.

Methods: Adults with unresectable HCC and an Eastern Cooperative Oncology Group performance status of 0 or 1 were enrolled in a 3 + 3 trial design. The occurrence of dose-limiting toxicities was assessed through 29 days from the start of napabucasin administration. Additional endpoints included safety, pharmacokinetics, and preliminary antitumor efficacy.

Results: In the six patients who initiated treatment with napabucasin, no dose-limiting toxicities occurred. The most frequently reported adverse events were diarrhea (83.3%) and palmar-plantar erythrodysesthesia syndrome (66.7%), all of which were grade 1 or 2. The pharmacokinetic results for napabucasin were consistent with prior publications. The best overall response (per Response Evaluation Criteria in Solid Tumors [RECIST] version 1.1) was stable disease in four patients. Using Kaplan-Meier methodology, the 6-month progression-free survival rate was 16.7% per RECIST 1.1 and 20.0% per modified RECIST for HCC. The 12-month overall survival rate was 50.0%.

Conclusions: These findings confirm the viability of napabucasin plus sorafenib treatment, and there were no safety or tolerability concerns in Japanese patients with unresectable HCC.

Clinical trial registration: ClinicalTrials.gov identifier NCT02358395, registered on 9 February 2015.