Favourable Overall Survival with Myeloablative Allogeneic Stem Cell Transplantation for Follicular Lymphoma.

Introduction

Allogeneic stem cell transplantation (Allo-SCT) remains an option for patients with follicular lymphoma (FL). Our program employs a strategy using allo-SCT for patients (pts) with high risk disease based on clinical characteristics. We performed a retrospective analysis to examine long-term disease control and treatment-related mortality.

Methods

41 pts with indolent FL (follicular small cleaved [FSC], follicular mixed [FM] or FL grade 1,2 by WHO criteria) underwent allo-SCT at our institution between Jan 1989 and Dec 2005. Patients were in a chemosensitive remission at the time of SCT. The conditioning regimen consisted of busulfan (1 mg/kg PO q6h X4 days between 1989–200 and 3.2 mg/kg IV daily X 4days subsequently) and cyclophosphamide 60 mg/kg X 2 days. Cyclophosphamide 60 mg/kg X 2 days and TBI 12 Gy was used for unrelated donor SCT. GVHD prophylaxis was with cyclosporine A and methotrexate.

Results

There were 21 males and 20 females. The median age at the time of transplant was 45 years (range 24 to 58). Histologic subtype was: unclassified indolent FL: 3, Grade 1 or FSC: 17, Grade 2 or FM: 21. The median number of prior chemotherapy regimens was 2 (range 1 – 6) and was unavailable in 5. Prior anthracycline: 37, prior purine analog: 9, prior platinum-based: 20, prior auto-SCT: 1, prior rituximab: 11. The median time from diagnosis to allo-SCT was 23 months (range 6 – 161). 38 pts received BuCy conditioning. 2 patients underwent RIC SCT. Graft source was: matched related (MRD) bone marrow (BM): 28, MRD peripheral blood stem cells (PBSC): 4, Mismatch related (MMRD) bone marrow (BM): 1, MMRD PBSC: 2, matched unrelated donor (MUD) BM: 1, MUD PBSC: 1, and syngeneic BM: 4. The five year overall survival is 77% (95% confidence intervals 73 – 91%) with a median follow-up of 48 months post-SCT. Treatment-related mortality was 5 of 41 pts (12%). Non-relapse mortality was seen in one patient (3%). One patient has relapsed at over 3 years post-SCT while all recipients of syngeneic SCT remain in remission.

Conclusions

These results demonstrate that in selected patients, a fully myeloablative allo-SCT utilizing Busulfan-Cyclophosphamide conditioning provides excellent overall survival and disease control with low TRM. Prospective comparisons of RICSCT with myeloablative SCT should be performed in order to better evaluate these strategies.