A PILOT PHASE II TRIAL OF PSC 833 MODULATION OF MULTIDRUG RESISTANCE TO PACLITAXEL IN THE TREATMENT OF METASTATIC CARCINOMA OF THE BREAST

OBJECTIVES: I. Evaluate the antitumor activity, as measured by frequency of objective response and time to progression, of the multidrug resistance modulator PSC 833 in combination with paclitaxel in women with recurrent or metastatic breast cancer. II. Describe the toxicity of this regimen.

OUTLINE: All patients receive PSC 833 by mouth every 6 hours for a total of 12 doses. Paclitaxel is infused over 3 hours, after the 5th dose of PSC 833. Treatment is repeated every 3 weeks in stable and responding patients. PSC 833 must not be mixed with grapefruit juice. Growth factors may be used at the discretion of the investigator. Patients are followed every 3 months for the first two years, then every 6 months for years 2-5, and then annually thereafter.

PROJECTED ACCRUAL: It is anticipated that approximately 36 patients will be entered over 24 months if there are at least 6 responses in the first 17 patients.