Long-Term Follow-Up Of Reduced-Intensity Allogeneic Hematopoietic Stem Cell Transplantation For High Risk Follicular Lymphoma

Follicular lymphoma (FL) is the most frequent indolent lymphoma. Autologous hematopoietic stem cell transplantation (ASCT) allows durable progression-free survival in selected relapsed patients. Recently, the EBMT lymphoma working party has published the recommendations for ASCT and allogeneic hematopoietic transplantation (alloTPH) in FL. For those high-risk young patients relapsing after ASCT, alloTPH is a valid therapeutic option; the majority being done with reduced intensity conditioning (alloRIC).

Our aim is to describe the outcome of patients with FL who underwent an alloTPH in our cente. Factors potentially influencing outcome such us age, sex, FLIPI at diagnosis, disease status prior alloTPH, EBMT risk score, type of donor, graft vs host disease (GVHD) prophylaxis and development of GVHD were also analized.

Actuarial estimates of OS and PFS rates were calculated using the Kaplan-Meier method. OS was estimated from the date of transplantation to the date of death or last follow-up. PFS was defined as the time from transplantation until progression or death from any cause.

We retrospectively found 26 alloTPH in the period 1999 - 2013. Two alloTPH were conditioned with a myeloablative regimen. Patients who underwent an alloRIC (n=24) were all conditioned with Fludarabine 30 mg/m²/5 days and Melphalan 70 mg/m²/1 day.

AlloTPH was from a matched related donor in 70.8% of cases, from a mismatched related donor in 4.2%, matched unrelated donor in 8.3% and from a mismatched unrelated donor in 16.7%.

The median age was 49.5 years (range 35-61). The median time from diagnosis to alloTPH was 48 months (range 9 – 190), male: female ratio was 2:1. FLIPI at diagnosis was 0 in 16.7%, FLIPI 1 in 25%, FLIPI 2 in 33.3%, FLIPI 3 in 8.3% and FLIPI 4 in 16.7. Mean number of treatment pre alloTPH was 4.5 (range 2-6). Ten patients (41.7%) had previously received an ASTC.

Response before alloTPH was complete response in 54.2%, partial response in 37.5% and stable disease in 8.4%. The majority of patients (95.8%) had an EBMT risk score higher than 3.

Graft vs host disease prophylaxis consisted on cyclosporine + short course of methotrexate in 54.2%, cyclosporine + micophenolate in 41.7% and sirolimus + tacrolimus in 4.2%. In vivo T-cell depletion was done in 4 patients receiving grafts from a mismatched unrelated donor (ATG or alemtuzumab, 2 patients each).

Mean CD34 cells/Kg infused was 6.45 x10⁶/kg (range 1.92 – 15.6). The median time to granulocyte recovery (>0.5x10⁹/L) was 15 days (range 11-19) and the median time to platelets recovery (>50x10⁹/L) was 14 days (range 6-56).

Acute GVHD was developed in 45.8% of patients; it was global grade 1-2 in 36.4% ,and grade 3-4 in 63.6%. Chronic GVHD was present in 58.3% of patients. The median time of chronic GVHD presentation was 196 days after alloTPH (range 101 – 569 days).

Regarding opportunistic infections, 20.8% of patients reactivated CMV with no disease, 16.7% had intestinal disease due to CMV. Thirteen per cent of patients developed pulmonary fungal infection (i.e Aspergillus sp).

With a median follow up of 48.50 months (range 0-161), the 5 years OS was 66.1% (CI 95% 43.76 - 88.44) and the 5 years PFS was 63.8% (CI 95% 43.22 - 84.4). Overall morbidity at 3, 6 and 12 months after alloTPH was 5%, 5% and 10.3% respectively. Only 1 patient relapsed at 38 months after alloTPH but is still alive. Causes of death were refractory GVHD (n=5), sepsis (n=3) and acute renal failure due to microangiopathy (n=1).

Survival was influenced by GVHD prophylaxis. At the median time of follow up (48.50 months) patients receiving cyclosporine-methotrexate had an OS of 82.5% vs 30% for patients receiving cyclosporine-MMF (p<0.01).

Other variables (FLIPI at diagnosis, sex, age older than 60 years, the EBMT risk score pre alloTPH and disease status) had no influence on survival.

AlloTPH for high risk FL patients seems to overcome the negative effect of FL prognostic factors at diagnosis. This strategy shows an excellent disease control with a low transplant-related mortality.

No relevant conflicts of interest to declare.