Long Term Molecular Remissions after Autologous Haematopoietic Stem Cell Transplant in Follicular Lymphoma.

Background and aim of the study: Autologous stem cell transplant (ASCT) has been shown to be an effective treatment for first-line and relapsed follicular lymphomas (FL). But no long term molecular remission was described. The aim of this retrospective study was to determine the clinical and molecular outcome of patients with FL who received ASCT during a 12-year period.

Method: All patients who underwent ASCT for first-line or relapsed FL between January 1992 and December 2004 were included. Overall survival (OS) and progression-free survival (PFS) were estimated by Kaplan-Meier method and cumulative incidence of nonrelapse mortality (NRM), with relapse as a competing event, by Fine and Gray method.

Patient characteristics: Seventy-one patients with a median age of 45 years and a median follow-up of 108 months were analysed. The majority were of the subtype grade 1 (57 %), had a high tumour burden (50 %) and were treated in firstline (52 %). After an anthracyclin-based induction regimen, 12 patients were in first complete remission (CR), 25 in first very good partial response (VGPR), 8 in second CR and 26 in second VGPR. They received BCNU, Etoposide, Aracytine, Melphalan (BEAM in 58 %) or Cyclophosphamide, total body irradiation (42 %) as conditioning for the ASCT. The majority of them received an unpurged graft (58%).

Results : Thirty-eight patients were alive, 24 without progression between 4 and 12 years; 31 patients had died, 7 without progression. A total of 38 patients (55 %) developed recurrent lymphoma. Median OS was estimated at 8 years and 4 months. The ten-year PFS and the ten-year OS were 33 % and 47 %, respectively and the tenyear molecular PFS was 37 %. There was an apparent plateau on the remission duration curve at 32 % at 72 months and on the molecular remission duration curve at 37 % at 80 months. A plateau on the OS curve seemed to emerge at 41 % from the tenth year. Patients who received a purged graft had better OS and better PFS (median OS not reached versus 50 months, p = 0.08; median PFS not reached versus 22 months, p = 0.035) Three patients developed a secondary neoplasm and two a secondary myelodysplastic syndrome. The 10-year non-relapse mortality (NRM) was 20 %.

Conclusion : This long follow-up study showed a plateau on the PFS and on the molecular PFS curves, suggesting that a selected group of patients might be cured by ASCT.