Pemetrexed in Advanced Non-Small-Cell Lung Cancer: at Progression vs Maintenance Therapy After Induction Chemotherapy

Overview

Non-small-cell lung cancer (NSCLC) accounts for a majority (approximately 85%) of lung cancer cases. Patients with localized disease can be cured through surgery, but only 20 % are operable.For the majority of patients with advanced disease, palliative cytotoxic chemotherapy remains the recommended therapy. Chemotherapy prolongs survival and improves quality of life. The recommended first-line therapy is 4-6 courses of a platinum in combination with a third generation compound (e.g. gemcitabine, vinorelbine, docetaxel, pemetrexed, paclitaxel). After first-line therapy, it has been recommended to observe the patients and offer second-line chemotherapy at disease progression. Regimens for second-line therapy include docetaxel or pemetrexed monotherapy. Pemetrexed is less toxic and superior to gemcitabine in non-squamous NSCLC, whereas docetaxel is the recommended second-line therapy in squamous cell carcinoma. The results of the studies of maintenance pemetrexed therapy are encouraging; the observed survival benefit is clinically relevant and relatively large considering the poor survival in patients with advanced NSCLC. Furthermore, pemetrexed appears to be well tolerated. There are, however, several limitations to the studies that have been conducted: Relatively few elderly patients and no PS 2 patients were enrolled - and not all patients on the control-arms received pemetrexed at progression. The overall aim of this study is to investigate whether immediate maintenance pemetrexed therapy prolongs survival compared to observation and pemetrexed therapy at progression in patients with advanced NSCLC. Furthermore, it will be explored whether patients with 'performance status' 2 and elderly ≥ 70 years tolerate and benefit from maintenance therapy; and what characteristics and blood biomarkers are associated with sensitivity and tolerability of such therapy.

In previous studies without maintenance therapy, median overall survival (OS) for performance status (PS) 0-1 patients has been approximately 9 months, corresponding to 6 months from randomization in this study. We consider an improvement in overall survival of two months to be the minimum difference that will lead to routine use of maintenance pemetrexed in Norway. To demonstrate an improvement in median overall survival from 6 to 8 months with an α =0.05 and β =0.20, 198 evaluable patients are required on each arm. We expect a drop-out rate of maximum 10 %, and therefore intend to randomize a total of 436 patients (PS 0-1) - of which we expect 150 to be 70 years or older. Sample size is calculated on PS 0-1 patients only. In addition, PS 2 patients will be randomized until the required number of PS 0-1 patients have been accrued. We estimate that a total of 100 PS 2 patients will be enrolled - sufficient for hypothesis-generating analyses of the benefit of maintenance therapy in elderly and PS 2 patients. Based on experience from our previous studies we estimate that approximately 30% of patients will not complete or progress during induction chemotherapy; or be ineligible due deterioration of PS. Consequently, we need to include approximately 765 patients.