Phase III trial shows ADI PEG 20 did not meet primary endpoint in hepatocellular carcinoma- Polaris Group

Polaris Group announced that the phase III study of second line ADI-PEG 20 plus best supportive care versus placebo plus best supportive care in patients with advanced hepatocellular carcinoma (HCC) did not meet its primary endpoint of demonstrating overall survival (OS) benefits. Median OS was 7.8 months for ADI-PEG 20 vs. 7.4 months for placebo. However, analysis of study data revealed that patients with arginine depletion for 7 weeks or longer had a median OS of 12.5 months, compared to 6.3 months for patients with arginine depletion lasting less than 7 weeks.

It is believed that treating patients with ADI-PEG 20 depletes circulating arginine, thus starving cancer cells of arginine, which is an essential amino acid for these cancers. This results in the starved cancer cells being unable to survive and grow while leaving the body's normal cells unharmed. The statistically significant findings from the analysis of the study data appears to support this hypothesis.

Additionally, sorafenib naive patients appear to have benefited more than those who failed prior sorafenib treatment, suggesting that ADI-PEG 20 may be more efficacious in the first-line setting. The study also showed ADI-PEG 20 was well tolerated, with the most common side effects being fatigue and decrease of appetite. The full study results were presented at the American Society of Clinical Oncology's 2016 annual meeting in Chicago.