A randomised phase II study of pegylated arginine deiminase (ADI-PEG 20) in Asian advanced hepatocellular carcinoma patients

BACKGROUND: Human hepatocellular carcinoma (HCC) cells are largely deficient of argininosuccinate synthetase and thus auxotrophic for arginine. This study aims to investigate the efficacy and pharmacodynamics of pegylated arginine deiminase (ADI-PEG 20), a systemic arginine deprivation agent, in Asian HCC patients. METHODS: Patients with advanced HCC who were not candidates for local therapy were eligible and randomly assigned to receive weekly intramuscular injections of ADI-PEG 20 at doses of 160 or 320 IU m(−2). The primary end point was disease-control rate (DCR). RESULTS: Of the 71 accruals, 43.6% had failed previous systemic treatment. There were no objective responders. The DCR and the median overall survival (OS) of the intent-to-treat population were 31.0% (95% confidence interval (CI): 20.5–43.1) and 7.3 (95% CI: 4.7–9.9) months respectively. Both efficacy parameters were comparable between the two study arms. The median OS of patients with undetectable circulating arginine for more than or equal to and <4 weeks was 10.0 (95% CI: 2.1–17.9) and 5.8 (95% CI: 1.4–10.1) months respectively (P=0.251, log-rank test). The major treatment-related adverse events were grades 1–2 local and/or allergic reactions. CONCLUSIONS: ADI-PEG 20 is safe and efficacious in stabilising the progression of heavily pretreated advanced HCC in an Asian population, and deserves further exploration.