Southwestern oncology Group phase II trial (S0526) of pemetrexed in bronchioloalveolar carcinoma subtypes of advanced adenocarcinoma

Background: Pemetrexed, a multitargeted antifolate drug, is an active agent in non-small-cell lung cancer (NSCLC), especially adenocarcinomas. Based on preclinical data supporting the relevance of alpha-folate receptors in adenocarcinoma of the bronchioloalveolar carcinoma (BAC) subtype, this trial was designed to assess pemetrexed in patients with this pathologic subtype of lung adenocarcinoma. Patients and Methods: Patients with histologically confirmed stage IIIB (with malignant pleural effusion) or stage IV adenocarcinoma with BAC features or pure BAC were eligible. Treatment consisted of pemetrexed, 500 mg/m², administered intravenously every 21 days. Results: Of 27 patients enrolled, 24 were eligible and assessable for adverse events: Toxicity was primarily hematologic, consisting of leukopenia/neutropenia, thrombocytopenia, and anemia. The median follow-up among patients still alive (n = 8) was 35 months (range, 26-47 months). Among 17 patients with measurable disease, the response rate was 23% (all partial responses; 95% confidence interval [CI], 10%-56%). The median progression-free survival (PFS) and overall survival (OS) were 6 and 25 months, respectively. Conclusion: Pemetrexed is active and well tolerated and, in patients with adenocarcinoma BAC subtypes, likely related to its underlying mechanism of action as a multitargeted antifolate drug.