Introduction: The role of hematopoietic stem cell transplant remains undefined in the treatment of many peripheral T-cell lymphoma (PTCL) subtypes including PTCL not otherwise specified (PTCL-NOS), angioimmunoblastic T-cell lymphoma (AITL), and anaplastic large cell lymphoma (ALCL). Specifically, it is unclear whether consolidative transplant benefits patients who achieve a complete response to induction chemotherapy (CR1). At the same time, few studies have directly compared autologous stem cell transplant (auto-SCT) to allogeneic stem cell transplant (allo-SCT) in the setting of relapsed/refractory (R/R) disease. Here, we describe our outcomes using auto-SCT and allo-SCT for PTCL across different clinical contexts.

Methods: We conducted a retrospective review of adult patients with PTCL-NOS, AITL, or ALCL who received an auto-SCT or allo-SCT between 2009 and 2024 at the University of California San Diego. Baseline patient/disease characteristics, induction therapy outcomes, and transplant efficacy outcomes were obtained. Treatment responses were graded by the Lugano criteria, with objective response rate (ORR) comprising complete and partial responses. Additional outcomes included assessing outcomes of patients who went on to receive allo-SCT after having first received auto-SCT. Survival was estimated with the Kaplan-Meier method and significance between survivals was calculated utilizing Cox proportional hazards.

Results: A total of 51 patients with PTCL were included (18 PTCL-NOS, 19 AITL, 13 ALK- ALCL, 1 ALK+ ALCL). At time of first transplant, the median age was 61 (range, 26-75). 32 patients (63%) were male. Among 25 patients with international prognostic index scores available, 12 had a score ≤2 while 13 had a score >2. Ten patients (20%) had >1 extranodal site of disease involvement. Patients received a median of 2 lines of induction chemotherapy prior to first transplant (range, 1-4).

Among 14 patients with ALCL who underwent transplant, all first received auto-SCT. Six patients underwent consolidative auto-SCT after having achieved CR1; the ORR was 100%. One patient relapsed and received allo-SCT, subsequently achieving remission. After a median follow-up time of 49.3 months, median progression-free survival (PFS) for these 6 patients was not reached (NR) (95% CI, NR – NR) while median overall survival (OS) was NR (95% CI, NR – NR). Eight of 14 patients were R/R to induction chemotherapy prior to receiving auto-SCT; the ORR was 100%. One patient subsequently relapsed and received additional salvage chemotherapy. After a median follow-up time of 104.4 months, median PFS for these 8 patients was NR (95% CI, 87.7 months – NR) while median OS was NR (95% CI, NR – NR).

Among 37 patients with AITL or PTCL-NOS, 15 (8 AITL, 7 PTCL-NOS) received a consolidative transplant in CR1 (all auto-SCT); the ORR was 100%. Eight patients subsequently relapsed, of whom 6 (2 AITL, 4 PTCL-NOS) proceeded to allo-SCT (with an ORR of 83%). After a median follow-up time of 76.3 months, median PFS of these 8 AITL and 7 PTCL-NOS patients was 92.5 months (95% CI, 31.2 – not reached) and 17.92 months (95% CI, 5.0 – NR), respectively while median OS was 166.4 months (95% CI, 37.9 – NR), and NR (95% CI, 46.1 – NR), respectively.

Of 37 patients with AITL or PTCL-NOS, 22 were R/R to initial induction therapy prior to undergoing transplant (10 auto-SCT, 12 allo-SCT), with a median follow-up time of 64.2 months. The ORR for the 10 auto-SCT first patients was 80%; seven of 8 responders subsequently relapsed, and 3 proceeded to allo-SCT (with an ORR of 67%). Median PFS of these 10 patients was 29.9 months (95% CI, 4.3 – NR) while median OS was 101.0 months (95% CI, 24.4 – NR). The ORR for the 12 allo-SCT first patients was 92%; three of 11 responders subsequently relapsed. Median PFS of these 12 patients was NR (95% CI, 8.8 months – NR) while median OS was NR (95% CI, 12.8 months – NR).

Conclusion: In this patient series, we demonstrate that in the case of ALCL, auto-SCT as choice of first transplant (regardless of disease status) appears effective at achieving a durable response. Furthermore, we present data highlighting that allo-SCT may be associated with a better ORR and lower likelihood of relapse compared to auto-SCT in the setting of R/R AITL and PTCL-NOS. Nevertheless, further research is needed to determine if allo-SCT prolongs PFS and OS in these cases, given the greater toxicity risks that remain with allo-SCT.

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2025
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