Washington Editor

Phoenix Pharmacologics Inc. started a Phase III confirmatory study on a cancer drug that demonstrated tumor regression in 47 percent of patients in a Phase II trial.

The product, ADI, or arginine deiminase, is a mycoplasma protein produced by recombinant DNA technology in E. coli. It is being studied in terminal liver cancer patients.

Discovered by Phoenix Pharmacologics, of Lexington, Ky., ADI is formulated with polyethylene glycol to decrease its immunogenicity and increase its circulating half-life in vivo.

Mike Clark, president and CEO of Phoenix Pharmacologics, told BioWorld Today the company in late October initiated an 80-patient, open-label Phase III at the Pascale National Cancer Institute in Naples, Italy. Beyond that trial, the company expects to start a second pivotal Phase III of 70 patients in the U.S. sometime in the second quarter of 2004.

ADI has been used in humans in the U.S., Italy and Taiwan. The candidate produced positive activity in Phase II trials, released by the company in July 2003. Two of 19 participating patients entered complete remission without any clinical evidence of disease, seven experienced a greater-than-50 percent remission of their tumor, and seven showed stable disease with no increase in tumor size. At six months, 14 continued to benefit from treatment and their average survival was five times greater than the historical life expectancy for comparable patient populations, the company said.

Patients in the study have primary liver cancer, or hepatocellular carcinoma, which is known to arise more frequently in people with chronic hepatitis C virus infections. About 50,000 people die each year in the U.S. and Europe combined from the cancer, the company said.

Clark said the company expects to file for regulatory approval in Europe late next year. He expects to file in the U.S. in 18 months based on both Phase III trials, plus some additional data.

Phoenix Pharmacologics is considering partnering ADI. Elsewhere in the pipeline, the company is developing Uricase (urate oxidase) for hyperuricemia, gout and tumor lysis syndrome. It currently is in Phase I trials.