Maintenance therapy with ex vivo expanded lymphokine‐activated killer cells and rituximab in patients with follicular lymphoma is safe and may delay disease progression

Summary Anti‐cluster of differentiation 20 (CD20) monoclonal antibodies (mAbs) have shown promise in follicular lymphoma (FL) as post‐induction therapy, by enhancing antibody‐dependent cellular cytotoxicity (ADCC). However, cytotoxic cells are reduced after this treatment. We hypothesised that ex vivo expanded lymphokine‐activated killer (LAK) cells administered to FL‐remission patients are safe and improve anti‐CD20 efficacy. This open, prospective, phase II, single‐arm study assessed safety and efficacy of ex vivo expanded LAK cells in 20 FL‐remission patients following rituximab maintenance. Mononuclear cells were obtained in odd rituximab cycles and stimulated with interleukin 2 (IL‐2) for 8 weeks, after which >5 × 10 8 LAK cells were injected. Patients were followed‐up for 5 years. At the end of maintenance, peripheral blood cells phenotype had not changed markedly. Natural killer, LAK and ADCC activities of mononuclear cells increased significantly after recombinant human IL‐2 (rhIL‐2) stimulation in all cycles. Rituximab significantly enhanced cytotoxic activity. No patients discontinued treatment. There were no treatment‐related serious adverse events. Three patients had progressed by the end of follow‐up. After a median (interquartile range) follow‐up of 59.4 (43.8–70.9) months, 85% of patients remained progression free. No deaths occurred. Quality‐of‐life improved throughout the study. Post‐induction LAK cells with rituximab seem safe in the long term. Larger studies are warranted to confirm efficacy.