Polaris Group and The Ludwig Institute for Cancer Research Ltd Initiate Phase 2 Trial of Amino-Acid Degrading Enzyme, ADI-PEG 20, in Patients with Small Cell Lung Cancer

NEW YORK and SAN DIEGO, Feb. 14, 2011 /PRNewswire/ -- Polaris Group (Polaris) and The Ludwig Institute for Cancer Research (LICR) today announced the enrollment of the first patient in a Phase 2 clinical trial evaluating ADI-PEG 20 in the treatment of small cell lung cancer (SCLC).  The trial, sponsored by LICR, is enrolling patients at Memorial Sloan-Kettering Cancer Center and Duke University Medical Center and will soon commence at St. Bartholomew's Hospital in London.

This study will evaluate the effectiveness of ADI-PEG 20 in patients with relapsed or refractory SCLC. Patients will be enrolled in two cohorts, each of which will have the sample size determined through a Simon two-stage design. SCLC is the fastest growing and most aggressive form of lung cancer and accounts for approximately 15 percent of all cases. Once diagnosed, few patients survive more than two years with current treatment.

ADI is a microbial enzyme, arginine deiminase, that degrades the amino acid arginine. ADI-PEG 20 is ADI conjugated with polyethylene glycol (PEG).  Since arginine can be internally synthesized in normal cells via the urea cycle, but not in certain cancer cells if they lack the necessary enzyme(s) to make arginine, deprivation of arginine caused by ADI-PEG 20 can selectively kill cancer cells without affecting the growth of normal cells. In preclinical models, ADI-PEG 20 eliminated arginine from the blood and showed substantial anti-tumor activity for arginine-dependent tumors.  In clinical trials, ADI-PEG 20 was also found to safely and efficiently eliminate arginine from the blood, and tumor responses as well as extension in overall survival have been observed in hepatocellular carcinoma and melanoma patients treated with ADI-PEG 20.

Amino acid deprivation is an established approach in the treatment of cancer and is exemplified by asparaginase, a widely used treatment for childhood leukemia. Lloyd J. Old, M.D., Director of the New York Branch of LICR and a key figure in the development of amino-acid deprivation therapy for childhood leukemia, has guided the scientific, clinical and early commercial development of ADI-PEG 20. Dr. Old states, "Enzymes, such as asparaginase and arginine deiminase, represent a novel class of cancer therapeutics which, used alone or in combination with other treatments, has the potential to be a promising new approach to the treatment of the disease."

"A long held dream in cancer research has been to discover factors required by cancer cells that are not essential for normal cells," said Dr. Old. "An important step in this direction came from findings over 40 years ago that certain cancer cells lacked enzymes necessary for the synthesis of asparagine, a non-essential amino acid for growth of normal cells. In mice, the asparagine-degrading enzyme asparaginase has strong anti-tumor activity against tumors that require this amino acid. The success of asparaginase in childhood leukemia validated this therapeutic approach and initiated a search for other non-essential amino acids that were required by cancer cells and for the corresponding amino acid degrading enzymes that could be exploited for therapeutic purposes. This long search was rewarded by the finding that the non-essential amino acid arginine was required by certain cancer cells, such as melanoma and SCLC that lack an arginine synthesizing enzyme."

SCLC is a uniquely suitable tumor type to test the anti-tumor activity of ADI-PEG 20 in humans since more than 70 percent of small cell lung cancers lack the arginine synthesizing enzyme, argininosuccinate synthetase.  While SCLC is often highly sensitive to cytotoxic agents, it shows a relatively rapid development of drug resistance.

"We are delighted to expand our relationship with Dr. Old and The Ludwig Institute and are hopeful that this approach will be successful in patients with SCLC, as current therapies offer little hope for long term survival," said Bor-Wen Wu, Ph.D., CEO of Polaris. "Dr. Old and his seminal work on amino acid degrading enzymes has been an inspiration to us as we search for drugs to treat cancer, and we are enthusiastic about the potential of ADI-PEG 20 in SCLC patients."

Argininosuccinate synthetase, the arginine synthesizing enzyme, can potentially serve as a biomarker to select patients who may respond to arginine depletion with ADI-PEG 20. Using this biomarker, Polaris and collaborators have identified multiple other cancers that are significantly deficient in the enzyme argininosuccinate synthetase and may be susceptible to ADI-PEG 20 treatment. The company plans to initiate clinical trials of ADI-PEG 20 in these other cancers later this year, including a pivotal multinational Phase 3 study for hepatocellular carcinoma.

About The Ludwig Institute for Cancer Research

The Ludwig Institute for Cancer Research Ltd is a non-profit research organization with more than 600 scientists at research sites in North and South America, Europe and Australia.  The Institute pursues scientific discoveries, identifies those with potential human benefit, and rapidly translates them into clinical applications through its distinctive not for profit biotech structure. For more information visit www.licr.org

About Polaris Group

Polaris Group is a privately held biopharmaceutical company that focuses on the development of drugs to treat cancer. For more information visit www.polarispharma.com

SOURCE Polaris Group