Nonmyeloablative Allogeneic Transplantation (NMT) for Relapsed Follicular Lymphoma (FL): Continuous Complete Remission with Longer Follow-Up.

NMT carries the promise of long-term disease control in FL by graft-versus-lymphoma immunity. We investigated the long-term efficacy of this strategy. Between March 1999 and April 2005, 47 consecutive patients were enrolled, ranging in age from 33 to 68 years (median, 53 years). The time from diagnosis to transplantation ranged from 7 months to 24 years (median, 3 years). All patients had recurrent chemosensitive FL. Each patient had received 2 to 7 (median, 2) chemotherapy regimens. Eight patients (17%) had failed a prior autologous transplantation. At the time of transplantation, 29 patients (61%) were in PR, and 18 (31%) were in CR. The conditioning regimen consisted of fludarabine (30 mg/m² daily for 3 days), cyclophosphamide (750 mg/m² daily for 3 days) and rituximab (Khouri, Blood 2001). This was followed by an infusion of HLA-matched hematopoietic cells from related (n=45) or unelated donors (n=2). Tacrolimus and methotrexate were used for graft-versus-disease (GVHD) prophylaxis. All patients achieved CR after transplantation. The median time to achieve CR in patients who had evidence of active disease at study entry was 5.5 months. Two relapses occurred. One was observed at 18 months; this patient responded to DLI with a continuous CR at 24+ months. The other patient who developed a relapse, was found to be simultaneously in graft failure 20 months after his transplantation. That patient was treated with rituximab and is still in CR at his last follow-up 4 years later. Eighteen patients had PCR evidence of bcl-2 translocation in the bone marrow at study entry. There were a total of 100 bone marrow post-treatment PCR samples available for analysis. Ninety eight samples that are drawn at a median time of 45 months after transplantation (range 4 months to 72 months) showed a negative PCR result. Two samples from 2 different patients were PCR-positive early after transplant; they became PCR-negative 3 months later. With a median follow-up time of 56 months (range, 19–94 months), the estimated overall survival (OS) and current progression-free survival (CPFS) rates at 6 years were 85% (95% confidence interval [CI], 71%–93%) and 83% (95% CI 69%–91%), respectively. The incidence of acute grade II–IV GVHD was 11% (95% CI, 31%–66%). The incidence of chronic extensive and limited GVHD, was 51% (95% CI, 44%–78%). Of the 28 patients who developed chronic GVHD, 20 (71%) had a de novo onset. The median time of onset of chronic GVHD was 262 days after transplantation, and the OS of patients with chronic GVHD was 89%, with a median follow-up time of 57 months (range, 19–94 months). Only five patients of the whole study group are still receiving immunosuppressive therapy at the time of their last follow-up. In conclusion, the longer follow-up of our study does provide further insight into long-term disease activity and regimen toxicity of NMT for FL, laying the groundwork for prospective comparative trials. We believe that the described results are a step forward toward finding a cure for this disease.