Meta-analysis to evaluate the role of interferon in follicular lymphoma

Purpose: To determine whether interferon (IFN)-α2, when given with or following chemotherapy, influences response rate, remission duration, and survival in newly diagnosed patients with follicular lymphoma. Patients and Methods: Ten phase III studies evaluating the role of IFN-α2 in 1,922 newly diagnosed patients with follicular lymphoma were analyzed. Updated individual patient data were used to perform meta-analyses for response, survival, and remission duration. Results: The addition of IFN-α2 to initial chemotherapy did not significantly influence response rate. An overall meta-analysis for survival showed a significant difference in favor of IFN-α2, but also showed significant heterogeneity between studies. Further analyses were carried out in order to explain this heterogeneity, and to define the circumstances in which IFN-α2 prolonged survival. The survival advantage was seen when IFN-α2 was given: (1) in conjunction with relatively intensive initial chemotherapy (2P = .00005), (2) at a dose ≥ 5 million units (2P = .000002), (3) at a cumulative dose ≥ 36 million units per month (2P = .000008), and (4) with chemotherapy rather than as maintenance therapy (P = .004). With regard to remission duration, there was also a significant difference in favor of IFN-α2, irrespective of the intensity of chemotherapy used, IFN dose, or whether IFN was given as a maintenance strategy or with chemotherapy. Conclusion: When given in the context of relatively intensive initial chemotherapy, and at a dose ≥ 5 million units (≥ 36 × 10⁶ units per month), IFN-α2 prolongs survival and remission duration in patients with follicular lymphoma.