Role of Allogeneic Stem Cell Transplantation (AlloSCT) in Patients Affected By Peripheral T-Cell Lymphomas (PTCL): No Difference in Outcome Between Patients Allografted at Diagnosis and in First Chemosensitive Relapse

Introduction: Despite novel therapies are under investigation in peripheral T-cell lymphomas (PTCL), the majority of the patients (pts) still have a dismal outcome. AlloSCT seems an effective approach in the salvage setting, but very small series of pts have been transplanted at diagnosis.

Methods: We report the long-term outcome (median follow-up of 60 months) of 72 pts affected by PTCL who underwent AlloSCT at diagnosis (Allo1) (n=23) or for chemosensitive relapse (Allo2) (n=49) that have been enrolled in two transplantation protocols. Pathological classification included: 20 PTCL-not otherwise specified (PTCL-NOS), 2 anaplastic large cell lymphoma (ALCL) and 1 rare subtype in Allo1 group; 18 PTCL-NOS, 11 ALCL, 8 AILD and12 rare subtypes in Allo2 group. Donor sources were HLA-matched siblings [n=39: n=13 Allo1 and n=26 Allo2 (p=0.80)], matched or mismatched unrelated donors [n=25: n=10 Allo1 and n=15 Allo2 (p=0.30], and haploidentical family donors [n=8, only in the Allo2 group]. All pts underwent transplant with chemosensitive disease: 45 in complete remission (CR) (63%) [n=20 Allo1, n=25 Allo2 (p=0.003)]; 27 in partial remission (PR) (37%) [n=3 Allo1, n=24 Allo2 (p=0.003)]. In the Allo2 group, 37 pts (75%) were allografted in first relapse and 12 in second relapse.

Results: In the Allo1 group, at a median follow-up of 59 months, of the 23 pts 15 (65%) are alive in CR, 4 (17%) died for progressive disease (PD), 3 for non-relapse mortality (NRM, 13%) and 1 for myocardial infarction. In the Allo2 group, at a median follow-up of 64 months, of the 49 pts 31 (63%) are alive (29 in CR), 11 (22%) died for PD and 6 (12%) for NRM while 1 for a second cancer. Five years crude cumulative incidence of relapse was 18% and 38% in Allo1 and Allo2 group (p=0.11), respectively. Five-year relapse-free survival (RFS), progressive-free-survival (PFS), and overall-survival (OS) were as follows: 80%, 60% and 62%, respectively, in Allo1 group; 61%, 47%and 59%, respectively, in Allo2 group without any statistical difference. However, we observed a significant difference in PFS between pts allografted at diagnosis and those in second-relapse (5-year PFS 61% versus 16%, p=0.0044) but not between the allografted at diagnosis and first-relapse (5-year PFS 61% versus 57%, p=0.92). When analyzed pts affected by PTCL-NOS, a better PFS trend was confirmed in pts receiving allograft at diagnosis or in first relapse as compared to second relapse [5-year PFS: 65% versus 55% versus 25%, respectively, (p=0.2)]. Pts who went to alloSCT in first CR did not have a significant advantage [5-year PFS and OS: 59% versus 43% (p=0.44); 60% versus 58% (p=0.82) in Allo1 and Allo2 group, respectively].

Conclusions: Despite the limitations due to the sample size, this is the first analysis in this setting. AlloSCT should be not indicated as a consolidation of first complete or partial remission approach/treatment outside a clinical trial. In fact, AlloSCT is very effective in patients with chemosensitive first relapse.