Polaris Group reports phase III study results of ADI-PEG 20 plus best supportive care in advanced hepatocellular carcinoma

The full study results were presented at the American Society of Clinical Oncology’s 2016 annual meeting in Chicago

Polaris Group has 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 (p = 0.884, HR=1.022 [95 per cent CI: 0.847, 1.233]). However, analysis of study data revealed that patients with arginine depletion for seven weeks or longer had a median OS of 12.5 months, compared to 6.3 months (P < 0.0001) for patients with arginine depletion lasting less than seven 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 na i ve 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 a plenary session by the lead investigator, Dr Ghassan K Abou-Alfa from the Memorial Sloan Kettering Cancer Center, at the American Society of Clinical Oncology’s 2016 annual meeting in Chicago.

“We are encouraged to see the overall survival benefit demonstrated by ADI-PEG 20 in the patient population with prolonged arginine depletion, which supports the theory that arginine depletion can be a safe way to extend life for these very ill patients,” said John Bomalaski, Executive Vice President, Medical Affairs at Polaris Pharmaceuticals. “We have already identified new combination therapy strategies that can significantly prolong arginine depletion and enable ADI-PEG 20 to synergise with current cancer treatments as shown in early stage clinical studies. We are making plans to move these combination therapies into late stage clinical development in the near future.”