Interferon as therapy for multiple myeloma: an individual patient data overview of 24 randomized trials and 4012 patients.

Many randomized trials have evaluated alpha-interferon as myeloma therapy, some suggesting a benefit and others not. Most were too small to give reliable answers, so a systematic overview has been performed to provide a more reliable estimate of the effect of interferon. The main end-points were response rates (induction trials), progression-free survival (PFS) and overall survival (OS). Individual patient data were supplied for 24 trials involving 4012 patients, 12 induction trials (2469 patients) and 12 maintenance trials (1543 patients). In induction, response rates were slightly better with interferon (57.5% versus 53.1%, P = 0.01). PFS was better with interferon (33% versus 24% at 3 years, P < 0.00001), an effect seen in both induction (P = 0.0003) and maintenance (P < 0.00001) trials. Median time to progression was increased by about 6 months in both settings. OS was somewhat better with interferon (53% versus 49% at 3 years, P = 0.01) with median survival increased by about 4 months. This benefit was restricted to the smaller trials. The effect of interferon was not significantly related to the dose or duration of interferon or to patients' characteristics. PFS was improved with interferon, but the survival benefit, if any, was small and needs balancing against cost and toxicity.