Impact of bone marrow involvement in patients with peripheral T-cell lymphoma undergoing autologous stem cell transplant.
Authors: Stuver Robert , Mazloom Anita , Ganesan Nivetha , Horwitz Steven M. , Moskowitz Alison J. 
Published: June 2022

7550 Background: Nodal-based T-cell lymphomas (PTCL) are treated with induction therapy and consideration for autotransplant (autoSCT) in first remission. The impact of bone marrow (BM) involvement at diagnosis and at autoSCT is unclear. Methods: We performed a retrospective review of consecutive patients with PTCL-NOS, AITL, and ALCL who received autoSCT in first remission at Memorial Sloan Kettering Cancer Center from 1997-2021. For BM involvement at baseline, patients were classified as positive (≥5% by histology), any involvement (by histology and/or at least 1 high-sensitivity [HS] assay, referring to flow or clonal TCR gene rearrangement), or negative (no involvement by histology and at least 1 negative HS assay). Patients with no baseline BM biopsy were excluded. At end of therapy (EOT, after induction but prior to autoSCT), BM involvement was considered positive (≥5% by histology), minimal residual disease positive (MRD+, no histological involvement but at least 1 positive HS assay), and MRD- (no histological involvement and at least 1 negative HS assay). Patients with no EOT BM but negative baseline BM were included as a separate cohort. Patients with no baseline BM and no EOT BM were excluded, as were those with baseline BM involvement and no EOT BM. The Kaplan-Meier method was used to estimate survival and compared using log-rank tests. Results: A total of 135 patients were included. Median follow-up after autoSCT for survivors was 56 months. The 5-year PFS/OS for the entire cohort was 45% and 65%, respectively. By histology, 5-year PFS/OS for PTCL-NOS (N = 27), AITL (N = 78), ALK+ (N = 8) and ALK- (N = 21) ALCL was 36%, 37%, 75%, 74% (p = 0.005), and 51%, 59%, 100%, 85% (p = 0.01). Among those with adequate baseline BM evaluation (N = 98), 31 were positive, 52 had any involvement, and 44 were negative. Five-year PFS and OS in the positive, any involvement, and negative groups was 46%, 42%, 44% (p = 0.82), and 63%, 61%, 74% (p = 0.27). Of those with adequate EOT BM evaluation (N = 72), 1 was positive, 17 were MRD+, and 43 were MRD-; 32 patients had no EOT BM but negative baseline BM. Five-year PFS and OS by the EOT positive, MRD+, MRD-, and no EOT BM but negative baseline groups was 0%, 37%, 45%, 45% (p = 0.86), and 0%, 92%, 59%, 71% (p = 0.39). Of the 17 patients with MRD+ EOT BM, 14 (82%) had AITL. Two-year PFS/OS in the AITL only cohort by EOT BM was 0%, 54%, 48%, 33%, and 0%, 90%, 75%, 72%, for the positive, MRD+, MRD-, and no EOT BM but negative baseline groups (PFS: p = 0.4; OS: p = 0.3). Conclusions: In patients treated with upfront induction and autoSCT in first remission, neither BM involvement at diagnosis nor the presence of MRD at the time of autoSCT resulted in worse survival outcomes compared to those with no BM involvement. For patients with PTCL-NOS, AITL, or ALCL in first remission, baseline BM involvement or pre-autoSCT BM MRD+ should not dissuade use of autoSCT consolidation.