Hycamtin has been approved for the treatment of subjects with metastatic ovarian cancer after failure of initial or subsequent chemotherapy. After initial therapy, cancer cells frequently become resistant to existing chemotherapies. Hycamtin produced responses after progression with prior chemotherapy used to treat ovarian cancer, including platinum compounds and paclitaxel.
In an open, randomized comparison study, 20% of subjects receiving Hycamtin responded to treatment compared to 12% of subjects receiving paclitaxel. Response was defined as 50% or greater shrinkage in tumor size. Median progression-free survival or time to progression for all treated subjects, defined as the time when the tumor progresses, was both statistically and clinically significant, indicating that subjects receiving Hycamtin experienced progressive disease less rapidly--23 weeks compared to 14 weeks for paclitaxel.
The efficacy of Hycamtin was confirmed in an additional open, noncomparative study. In each study, the dosage of Hycamtin was 1.5 mg/m2 administered intravenously over 30 minutes daily for five days and repeated every 21 days.
As with many cancer chemotherapeutic agents, the main side effect demonstrated by Hycamtin in clinical trials was suppression of blood cells produced in the bone marrow that was predictable, noncumulative, reversible, and manageable. The most frequently reported non-hematologic side effects were gastrointestinal, including nausea and vomiting. However, only 8% of all subjects experienced severe nausea.
Hycamtin is the first topoisomerase I inhibitor to be approved for marketing in the United States. This new class of drugs kills cancer cells by inhibiting the enzyme topoisomerase I, which is essential in the replication of DNA in human cells. While several anticancer drugs act by inhibiting the related enzyme topoisomerase II, Hycamtin is the first agent to act against topoisomerase I.
Ovarian cancer is the leading cause of gynecologic cancer deaths among American women and will kill an estimated 14,800 women annually.