Current status of hematopoietic cell transplantation in patients with peripheral T-cell lymphoma including adult T-cell leukemia-lymphoma.

Peripheral T-cell lymphomas (PTCLs) are biologically diverse and clinically aggressive, and are difficult to control long-term with conventional immunochemotherapy. Hematopoietic cell transplantation (HCT) is a key treatment option. Autologous HCT (auto-HCT) as first-line consolidation has shown durable progression-free survival in phase 2 studies and in the auto-HCT arm of the randomized AATT trial (intent-to-treat PFS 30-49%), although its routine use after complete metabolic response remains controversial. A phase 3 trial comparing auto-HCT with observation is ongoing. For relapsed/refractory PTCL, expert consensus supports allogeneic HCT (allo-HCT) as the treatment of choice for eligible patients, with early referral and limited salvage therapy. While complete remission is ideal, partial remission is acceptable. Upfront allo-HCT is not recommended for unselected PTCL in light of the results of the AATT trial, but adult T-cell leukemia-lymphoma (ATL) is an exception. Multiple studies have shown graft-versus-ATL effects, supporting allo-HCT in aggressive ATL. Donor sources now include unrelated and haploidentical donors, with outcomes comparable to matched siblings. Despite advances, relapse after HCT remains a major challenge. Novel maintenance strategies and optimized transplant approaches are needed to further improve outcomes in PTCL and ATL.