Long-Term Outcomes of Allogeneic Stem Cell Transplant in Peripheral T-Cell Lymphoma

Introduction: Peripheral T-cell Lymphoma represents a heterogeneous group of lymphoid malignancies characterized by poor prognosis with 5-year overall survival (OS) about 25% with conventional chemotherapy. Autologous stem cell transplant (Auto-SCT), as consolidation, is often considered in first complete remission (CR), providing between 30 to 40% long term disease-free survival. However, patients receiving Auto-SCT in second CR or with refractory disease have poor outcomes with progression-free survival ranging from 15-20% to 0%, respectively. In such cases, allogeneic stem cell transplant (Allo-SCT) may provide long term disease control. We intended to study outcomes of Allo-SCT in peripheral T-cell lymphoma patients.

Methods: We have retrospectively evaluated long-term outcomes of adult peripheral T-cell lymphoma patients at Karmanos Cancer Institute. The objectives were to determine GVHD rate, overall survival (OS), relapse rate, progression-free survival (PFS) and non-relapse mortality (NRM) following Allo-SCT.

Results: Between January 2005 and December 2017, 39 patients underwent Allo-SCT. The different diagnoses included peripheral T-cell lymphoma, not-otherwise-specified (n=16), angioimmunoblastic T-cell lymphoma (n=8), anaplastic T-cell lymphoma (n=8), hepatosplenic T-cell lymphoma (n=2), cutaneous T-cell (n=3) and NK cell lymphoma (n=2). The median age at transplant was 50 years (range, 21-67). The median number of prior therapies was 2 (range, 1-5) and 12 patients (31%) had failed prior Auto-SCT. Sixteen patients (41%) were in CR and 2 (5%) were in partial remission at the time of Allo-SCT, whereas 12 (31%) patients had relapsed disease and 9 (23%) had refractory disease. Twenty-one patients (54%) received matched related and 18 patients (46%) had unrelated Allo-SCT. Myeloablative conditioning regimen was used in 22 patients (56%), whereas reduced intensity regimen was used in 17 (44%) patients.

Grade III-IV acute GVHD occurred in 25.6% (95% CI, 13.2-40.1%) and chronic GVHD occurred in 41% (95% CI, 25.1-56.3%). After a median follow-up of 3.08 years (95% CI, 2.49-7.28) among surviving patients, the estimated probabilities of 3-year OS and PFS were 35.9% (95% CI, 22.4-57.6%) and 32.5% (95% CI, 19.9-53%), respectively. The 3-year relapse rate was 23.9% (95% CI, 11.5-38.7%), whereas NRM was 35.9% (95% CI, 21.1-50.9%). No difference in OS and PFS was noticed in patients receiving Allo-SCT in first CR compared with patients receiving Allo-SCT beyond first CR (p=0.81; p=0.94). Similarly, no difference in OS and PFS was noted in patients with Allo-SCT followed by failed prior Auto-SCT compared with patients with upfront Allo-SCT (p=0.31; p=0.47). Seventeen of 39 patients were alive and 22 were deceased (n=7 disease relapse; n=15 NRM). Out of 39 patients, 13 (33%) alive patients are free of relapse and GVHD as of data analysis.

Conclusion: Our study suggests that Allo-SCT is a viable treatment option for peripheral T-cell lymphoma and appears to provide cure in these highly selected patients. The survival advantage was noted in patients beyond first remission; therefore, it should be considered in all transplant eligible patients. In addition, certain proportion of patients who failed prior Auto-SCT benefited from Allo-SCT, which points towards potential role of graft-versus-lymphoma effect.

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