Wed, Jul 06, 2016 - Page 12 News List

Polaris changes ADI-PEG 20 approach

By Ted Chen  /  Staff reporter

Biomedical company Polaris Group (北極星) yesterday said that it would continue developing its cancer treatment ADI-PEG 20, but with a new approach, following a setback in a clinical trial.

A phase III study of the effectiveness of ADI-PEG 20 as a second-line treatment for hepatocellular carcinoma (HCC) failed to demonstrate overall survival (OS) benefits, the company said in a statement on June 6.

The study showed that median OS was 7.8 months for patients receiving ADI-PEG 20, which was not significantly better than the 7.4 months for patients given a placebo.

Polaris Group chief executive officer Wu Bor-wen (吳伯文) told an investors’ conference that despite the setback, the company has formed a solid plan moving forward from the clinical trial.

ADI-PEG 20 is arginine deiminase (ADI) formulated with polyethylene glycol, with an average molecular weight of 20 kilodaltons (PEG 20), and the treatment is designed to degrade arginine, an amino acid crucial to tumor cell metabolism and the growth of certain cancers, Wu said.

An analysis of the clinical trial data showed that patients with arginine depletion for seven weeks or longer had a median OS of 12.5 months, compared with 6.3 months for patients with arginine depletion of less than seven weeks, Wu said.

“This outcome shows that the treatment is effective against cancer, as arginine-starved cancer cells are unable to survive and grow,” Wu said.

In addition, Wu said the study showed that ADI-PEG 20 was more beneficial for patients who have never had prior treatment with Nexarvar, a sorafenib-based drug for treating diseases including kidney and liver cancer, and thyroid carcinoma.

For some patients, prior treatment with Nexarvar reduced the arginine deprivation ability of ADI-PEG 20, and the company’s new treatment might be more effective as a first-line treatment, Wu said.

Nexarvar induces argininosuccinate synthase (ASS) expression, an enzyme that catalyzes the synthesis of argininosuccinate from citrulline and aspartate, which makes ADI-PEG 20 ineffective as a monotherapy option, Wu said.

The company said it would explore alternative roles for ADI-PEG 20, such as using the treatment as a component of combination therapy as a first-line treatment, as well as using higher dosages to promote longer arginine depletion, Wu said.

Wu added that in March, the firm began a number of clinical trials for ADI-PEG 20 on treating mesothelioma of the lungs and pancreatic cancer, and that regulatory approval for one of the indications might come in about 2018.

To obtain market approval, the company is to file biologics license applications with regulators, and expand its sales potential by testing more ASS-deficient tumors in trials, Wu said.

Combination research is becoming more common in new cancer drug development, but testing each combination candidate would require a tremendous amount of time, Polaris Group medical affairs executive vice president John Bomalaski said.

The company will also improve patient selection so that those who are more likely to benefit from ADI-PEG 20 are included in future clinical trials, Bomalaski said.

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