Outcome Of Patients With HTLV-1 Associated Adult T-Cell Leukemia/Lymphoma (ATL) Who Have Undergone Stem Cell Transplantation: A Retrospective Study Of The EBMT Lymphoma Working Party

Adult T-cell leukemia/lymphoma (ATL) is an aggressive malignancy of mature activated T-cells caused by the human T cell lymphotropic virus type I (HTLV-1). ATL carries a very poor prognosis because of intrinsic chemoresistance and severe immunosuppression. Indeed, prognosis of the two most frequent forms of the disease (acute ATL and ATL lymphoma) remains dismal with a median survival of less than 12 months. A recent worldwide metaanalysis demonstrated that the combination of zidovudine and interferon-alpha is highly effective in the chronic and acute subtypes of ATL and should be considered as standard first line therapy in that setting. However, because of the high rate of relapse in acute subtype and lymphoma, allogeneic stem cell transplantation (allo-SCT) is an attractive potentially curative option. A number of retrospective studies from Japan confirmed the feasibility of myeloablative or reduced-intensity conditioning allo-SCT in ATL patients and a large retrospective study reported a 3-year overall survival of 33%. No reports on allo-SCT are available outside Japan.

We performed a retrospective analysis of transplanted ATL patients in the EBMT registry.

Data could be retrieved for 21 HTLV-I seropositive patients transplanted between 2004 and 2010 for ATL (10 males, 11 females; median age 48 years; range 21-67; interquartile range 36-52). According to the Shimoyama classification, 7 (33%) patients had acute ATL, 12 (57%) had ATL lymphoma and 2 (9%) had an unknown subtype. At transplant, 12 (57%) patients were in complete remission, 5 (24%) patients were in partial remission and 4 (19%) patients were refractory. Four (19%) patients received autologous SCT (auto-SCT), all of whom died from relapsed/refractory disease in less than one year. Seventeen patients (81%) received allo-SCT (4 myeloablative, 13 reduced intensity and one unknown conditioning) from identical sibling (6), haploidentical relative (3), unrelated (7) or unknown donor (1). Of those who underwent allo-SCT 6/17 patients are alive and the majority of them (4/6) were in CR at time of allo-SCT. Eleven patients died (65%) within 2 years of allo-SCT (median time to death was 5 months), 8 of relapse/progression and 3 from transplant related causes (sepsis n=1; GVHD n=2.) Four patients developed acute GVHD (24%). Data on chronic GVHD were available for 15 patients. Eight patients developed chronic GVHD, 4 were alive at last FU, 2 died from relapse/progression and 2 died from GVHD. Conversely, seven patients did not develop chronic GVHD, 5 of them died from relapse/progression.

Overall these results indicate that allo-SCT but not auto-SCT may salvage a subset of ATL patients, particularly those transplanted in CR and who achieve chronic GVHD suggesting the existence of graft versus ATL effect. Although based on a low number of patients these data are consistent with those previously reported by Japanese studies.

Dreger:Riemser Pharma : Consultancy, Honoraria, Research Funding.