Recombinant interferon-α2b added to oral cyclophosphamide either as induction or maintenance in treatment-naive follicular lymphoma: final analysis of CALGB 8691

Recombinant interferon alpha-2b (IFN-α2) has direct and indirect antiproliferative effects in lymphoma, and may augment cytotoxicity when combined with chemotherapy. CALGB 8691 is a randomized study of daily oral cyclophosphamide (CPA) at 100 mg/m2 with or without IFN-α2 at 2 × 106 IU/m2 three times per week, followed by a second randomization between IFN-α2 maintenance (2 × 106 IU/m2 three times weekly) versus observation in treatment-naive patients with follicular lymphoma (FL). Five hundred eighty-one patients were randomized to either CPA (n = 293) or CPA plus IFN-α2 (n = 288). One hundred five responding patients were randomized to observation and 99 to maintenance IFN-α2. With a median follow-up of 11.5 years, the median event-free and overall survival (OS) for CPA induction alone were 2.5 years (95% CI 2.2, 3.0) and 9 years (95% CI 7.7, 10.2), compared to 2.4 years (95% CI 2.1, 3.1) and 8.4 years (95% CI 7.5, 11.1) for the combination arm (p = NS). Patients with a partial response (PR) and randomiz...