Matrix Reports Antitumor Efficacy of MPI 5017 at American Association for Cancer Research.

FREMONT, Calif.--(BUSINESS WIRE)--April 24, 1996--Matrix Pharmaceutical, Inc. (NASDAQ:MATX) reported today preclinical results of its vinblastine/epinephrine injectable gel (MPI 5017) in bladder tumors.

The study showed that intratumoral delivery of MPI 5017 was more effective than intratumoral or intraperitoneal (abdominal) administration of aqueous vinblastine solutions. Also, simple aqueous solutions of vinblastine injected intratumorally resulted in severe adhesions of the internal organs and surrounding connective tissue with the abdominable wall, whereas the MPI 5017 exhibited a much more favorable safety profile. A potent inhibitor of cell division via tubulin binding, vinblastine is one of the most efficacious single-agent chemotherapeutics, but systemic side-effects have often limited its clinical utility.

Richard E. Jones, Ph.D., vice president of research and development, commented, "We believe that MPI 5017 is one of our more promising product candidates. Since vinblastine is a cell-cycle specific drug, MPI 5017 may improve the safety and efficacy of the drug by localizing the effects of the drug to the site of administration in the tumor tissue and increasing its residence time within the tumor, while decreasing the incidence of side-effects associated with systemic delivery."

The study, presented today at the American Association of Cancer Research (AACR), evaluated the efficacy of intratumoral injection of MPI 5017 versus intratumoral or intraperitoneal injection of aqueous vinblastine solution in mouse tumor models. The study also evaluated MPI 5017 in an ectopic model (mouse bladder tumors implanted in the skin) versus a more clinically relevant orthotopic model (mouse bladder tumors implanted in the normal site of the tumor in the bladder wall).

The tests showed that intratumoral delivery of MPI 5017 was considerably more effective than intratumoral or intraperitoneal administration of vinblastine solution, as measured by the delay in tumor growth following treatment. At the end of the 30-day study period, five out of seven orthotopically grown tumors receiving a single dose of MPI 5017 had completely resolved. The study also showed that the orthotopic tumors grew much more aggressively than the ectopically grown tumors, and that vinblastine exhibited antitumor activity, even in these more aggressive tumors. The use of an orthotopic tumor model has been proposed to be more clinically relevent than ectopic tumors in preclinical drug screening efforts.

Matrix presented two other posters at the AACR meeting. These reported on preclinical studies of its anhydrous vehicle system and a new three-dimensional imaging technique for tumor autoradiograms.

Matrix is a leader in the formulation and development of novel site-specific treatments for cancer and serious skin diseases. The company's most advanced product candidates, AccuSite Injectable Gel and IntraDose Injectable Gel, utilize approved chemotherapeutic agents in a proprietary viscous gel formulation and are directly injected into solid tumors and skin lesions. The company is currently pursuing six disease indications for its AccuSite and IntraDose products, including three indications in Phase II trials, two indications in Phase III trials and one indication pending regulatory approval.

CONTACT: Matrix Pharmaceutical Inc.

Beverly Holley, 510/742-9900