Edatrexate (10-ethyl-deaza-aminopterin) (NSC #626715) with or without leucovorin rescue for malignant mesothelioma

BACKGROUND The Cancer and Leukemia Group B (CALGB) conducted sequential Phase II multicenter trials to evaluate the activity of edatrexate alone (E) or with leucovorin rescue (EL) in patients with malignant pleural mesothelioma (CALGB Protocol 9131). METHODS Twenty patients were accrued to the E portion of the study and received edatrexate, 80 mg/m2, intravenously over 20–30 minutes weekly. After a protocol amendment precipitated by excessive toxic events with E, 40 patients were enrolled in the EL arm and received the same dose of edatrexate with leucovorin, 15 mg orally, every 6 hours for 4 doses beginning 24 hours after edatrexate. Eligibility criteria included a CALGB performance status of 0–2 and no prior chemotherapy. A central pathology review was performed. Of the 58 patients included in this analysis (20 receiving E and 38 receiving EL), 36 had epithelial cell type and 22 had mixed or sarcomatous cell types. There were 31 patients with measurable disease and 27 with evaluable disease. RESULTS The overall response rate was 25% for E (95% confidence interval [95% CI], 9–49%) and 16% for EL (95% CI, 6–31%). There was a 5% complete response [CR] rate, a 10% partial response [PR] rate, and a 10% regression [R] rate for E and a 0% CR rate, a 3% PR rate, and a 13% R rate for EL. The median survival duration from study entry was 9.6 months and 6.6 months, respectively, for E and EL; 1-year survival was 50% and 32%, respectively, for E and EL. There were four early deaths with the E regimen (including two from neutropenic sepsis) and one early death with the EL regimen (from progressive disease). Principal toxicities included mu cositis, myelosuppression, and rash, which were less frequent with leucovorin rescue. CONCLUSIONS Moderate antitumor activity has been observed with both regimens. Leucovorin rescue ameliorated the mucosal, hematologic, and dermatologic toxicities of edatrexate, but also may have reduced its efficacy. Cancer 1999;86:1985–91. © 1999 American Cancer Society.