Marimastat in patients with advanced pancreatic cancer: a dose-finding study.

Patients with solid tumors, including carcinoma of the pancreas, express high levels of matrix metalloproteinases (MMP), and these enzymes are believed to be important for the growth, spread, and dissemination of most solid malignant tumors. Marimastat is the first orally available MMP inhibitor (MMPI) to be tested in humans and has been shown to inhibit the spread and growth of pancreatic cancer in animal models. The purpose of the present study was to define the toxicities, safety, and tolerance of various doses of marimastat and also to get an early indication of potential biologic activity in patients with advanced pancreatic cancer. The authors prospectively studied 64 patients with advanced carcinoma of the pancreas in whom standard treatments had failed. Eligible patients had a progressive rise in CA 19/9 levels of >25% over the 4-week period preceding their entry into the study. Patients were studied in groups of 8 to 10, with each group receiving escalating dosages ranging from 5 mg twice daily to 75 mg twice daily and 10 to 25 mg daily. Patients were considered for long-term (beyond 4 weeks) continuation treatment if clinical benefit, in the view of the investigator, was derived. Study endpoints were safety, tolerance, and changes in the rate of rise of CA 19/9, which were used as surrogate markers for disease progression. Marimastat was well tolerated. Musculoskeletal pain, stiffness, and tenderness emerged as dose-limiting toxicity. No other dose-related toxicities were observed. A reduced rate of rise of CA 19/9 was observed at dose levels of 5, 10, and 25 mg twice daily. The overall median survival was 160 days, with a 1-year survival of 21%. Marimastat was associated with an acceptable toxicity profile, and these preliminary data suggest that long-term oral administration is feasible and safe. Doses of 5, 10, and 25 mg twice daily were identified as the optimal doses to be tested in larger randomized studies.