Combination chemotherapy with gemcitabine and irinotecan in patients with previously treated carcinoma of an unknown primary site: a Minnie Pearl Cancer Research Network Phase II trial.

BACKGROUND: The current study was performed to evaluate the activity of combination chemotherapy with gemcitabine and irinotecan in patients with previously treated carcinoma of an unknown primary site.

METHODS: Patients with carcinoma of an unknown primary site who had received one previous chemotherapy regimen were eligible for this study. All patients received gemcitabine at a dose of 1000 mg/m2 intravenously (i.v.) and irinotecan at a dose of 100 mg/m2 i.v. on Days 1 and 8; treatment courses were repeated every 21 days. Patients were evaluated for response after completing two courses of treatment; responders/stable patients continued treatment for a recommended six courses.

RESULTS: Forty patients entered this multicenter, community-based Phase II trial between September 2000 and July 2003. Four of these 40 patients (10%) achieved objective responses (a partial response in 3 patients and a complete response in 1 patient). An additional 17 patients (43%) had stable disease/minor response at first reevaluation; 7 of these patients (18%) remained stable for longer than 6 months. The median survival for the entire group was 4.5 months, with 1-year and 2-year survival rates of 25% and 13%, respectively. The treatment was well tolerated by most patients. Neutropenia was the most common Grade 3/4 toxicity (according to the National Cancer Institute Common Toxicity Criteria, version 3.0) (occurring in 36% of patients). Myelosuppression-related complications were uncommon, as were severe nonhematologic toxicities.

CONCLUSIONS: The combination of gemcitabine and irinotecan has modest activity and is well tolerated in patients with recurrent/refractory carcinoma of an unknown primary site. Treatment-related toxicity, particularly myelosuppression, appears to be less severe than toxicity produced by the taxane and platinum regimens frequently used in the first-line therapy of these patients. Evaluation of the gemcitabine and irinotecan combination as first-line therapy is indicated.