A phase II trial of MEK inhibitor BAY 86-9766 in combination with sorafenib as first-line systemic treatment for patients with unresectable hepatocellular carcinoma (HCC).

Abstract

4103 Background: Sorafenib (S) is the only approved systemic treatment for unresectable HCC. Nevertheless, there remains an unmet medical need for more effective treatment options for this disease. BAY 86-9766 (B) is an oral, allosteric inhibitor of MEK, a key component of the MAP kinase pathway. This study evaluated the efficacy and safety of a combination therapy with B plus S in patients (pts) with HCC. Methods: This is a single arm, open-label, phase 2 study. Eligible were pts with unresectable HCC, Child-Pugh Class A, performance status (PS) 0-1, and no prior systemic anticancer therapy for HCC. Pts started Cycle 1 (21 days) with B 50 mg bid orally plus S 600 mg daily (200 mg AM, 400 mg PM) orally. If there was no hand-foot skin reaction, fatigue, or gastrointestinal toxicity ≥ grade 2, S was escalated to 400 mg bid from Cycle 2 on. Treatment continued until progression or withdrawal criteria were met. Tumor assessment was performed every 6 weeks during treatment. Safety was evaluated every week for the first 6 weeks and every 3 weeks thereafter. Results: Seventy pts from Asia started study treatment. Pts were predominantly male (86%); median age was 56 years; 54% had PS of 0 and 46% PS of 1. The vast majority had liver cirrhosis (83%) and infection with HBV (76%) or HCV (17%). Sixty-five were evaluable for efficacy per protocol. Three pts (5%) had confirmed partial response and 25 pts (38%) had prolonged stable disease (≥10 weeks), with a disease control rate of 43%. Median time-to-progression was 4.1 months. Survival data are not mature, yet. The most frequent drug-related adverse events (AEs) were rash (60%), diarrhea (59%), AST elevation (43%), vomiting (30%), nausea (29%), ALT elevation (26%), and anorexia (26%). There were 4 Grade 5 related AEs (hepatic failure, sepsis/hepatic encephalopathy, tumor lysis syndrome, and unknown cause, respectively). Dose modifications due to AEs were necessary in almost all pts. The median daily dose was 64.2 mg for B and 443.3 mg for S, respectively. Conclusions: B in combination with S showed antitumor activity in pts with HCC. However, frequent dose modifications due to AEs might have limited the treatment effect of this combination.