Cao, Miao

Abstract Introduction: T-PLL is a rare, aggressive leukemia with poor prognosis and limited therapies. Previous studies on T-PLL patients receiving an allogeneic stem cell transplant (alloSCT) are limited by small numbers with limited data on disease and transplant characteristics. Further, recent data from our large national cohort of patients demonstrated significant survival difference between TCL1A+ and TCL1A- T-PLL, and CD8+ T-PLL vs CD8- T-PLL. In this large multi-center series, utilizing comprehensive disease subtype and alloSCT clinical data, we evaluated prognostic and survival therapeutic outcomes in T-PLL patients that had an alloSCT with a particular focus on T-PLL disease subtypes. Methods: We retrospectively evaluated 572 diagnosed with T-PLL at 21 academic cancer centers throughout the USA between 2000-2023, of which we performed a further evaluation on the169 that proceeded with alloSCT. Overall survival (OS) and progression-free survival (PFS) were assessed using Kaplan-Meier methods and Cox proportional hazard models. Results: Among n=169 alloSCT recipients with T-PLL, the median follow-up time was 20.9 months post-alloSCT (range: 0.2-182.9), the median age at transplant was 59 years (range: 35-77) and 52% were male. In evaluated patients (n=109), TCL1A was positive by cytogenetics or FISH in 69%. As our recent analysis demonstrated significant differences in survival among specific subtypes of T-PLL, we evaluated outcomes in patients with CD4+CD8- T-PLL (n=90, 53%), CD4-CD8+ (n=17, 10%) T-PLL, and CD4+CD8+ T-PLL (n=52, 31%). 53% (87/164) had known nodal involvement at diagnosis identified by PET or CT scan and 45% (43/96) of known patients had minimal residual disease (MRD) at the time of transplant [defined as <5% T-PLL in marrow by flow, or +cytogenetics (e.g. TCL1A)] prior to alloSCT. At the time of alloSCT, 136 (80%) patients were in CR and 23 (14%) patients were in PR. Forty-nine (30%) had a myeloablative (MAC)conditioning regimen and 114 (70%) had a reduced intensity chemotherapy (RIC) conditioning regimen. Eighty (49%) patients had TBI as part of their regimen. The most common regimens were fludarabine (flu)/melphalan based regimens (n=44; 26.0%), flu/cyclophosphamide (cy) based regimens (n=33; 19.5%), flu/busulfan based regimens (n=22; 13.0%), flu/total body irradiation (TBI) (n=8; 4.7%), and cy/TBI (n=4; 2.4%). Across the whole cohort, the median OS and PFS post-alloSCT was 32.6 months (95% CI: 21.0-41.9) and 20.8 months (95% CI: 14.4-30.5) months while the 1-year cumulative incidences (CI) of NRM and relapse were 17% and 20%, respectively. The incidences of grade II-IV acute GVHD and cGVHD were 19% and 23%. There was no difference between patients with myeloablative conditioning (MAC) (n=49, 29%) when compared to patients that received reduced intensity conditioning (RIC) (n=114, 67%) in OS (33.1 vs 29.2; p=0.68) and PFS (20.2 vs 20.8; p=0.97). Patients that were MRD+ (n=31) had worse OS (22.2 vs 48.6; p=0.1) and PFS (14.1 vs 32.5; p=0.04) and higher rates of relapse (1-year relapse 20% vs 8%; p=0.08) than patients that were MRD- (n=50). PFS was improved in those who received alloSCT though only trended towards significance due to low numbers (HR 0.76, p=0.09). In subtype analysis, TCL1A+ T-PLL had significantly worse outcomes compared to TCL1A negative T-PLL. TCL1A+ disease had significantly worse OS (21.6 vs 63.1; p=0.01) and PFS (12.4 vs 50.7; p=0.01) compared to TCL1A-. Additionally, in TCL1A+ disease CI of NRM (24% vs 3%; p=0.02) and relapse (25% vs 12%; p=0.86) was higher vs TCL1A- PLL. CD4+CD8-, CD4-CD8+, and CD4+CD8+ disease had no difference in survival via either OS (28.0 vs 34.4 vs 21.0; p=0.17) or PFS (29.4 vs 23.5 vs 13.6; p=0.09) as well as no difference 1-year CI of NRM ( 11.6 vs 23.5 vs 26.2; p=0.35) and relapse (18.5 vs 23.5 vs 20.0; p=0.67).Conclusions: AlloSCT significantly improved outcomes for patients with T-PLL compared to those who did not proceed to alloSCT and remains he only curative therapy for those with T-PLL. OS, PFS, and CI relapse were significantly worse for patients with TCL1A+ subtype of T-PLL, or those with MRD positivity or PR prior to alloSCT. Novel strategies to decrease relapse such as post-alloSCT maintenance therapy to improve outcomes are urgently needed in these patients.

Introduction: T-PLL is a rare, aggressive malignancy with poor prognosis and limited therapies. Outside of prospective trials utilizing alemtuzumab, data is derived primarily from small retrospective series, and limited data on survival outcomes and therapeutic efficacy, particularly beyond frontline therapy are available. In this large multi-center series, with comprehensive clinical data, we evaluated survival and therapeutic outcomes in T-PLL patients, with a focus on identification of prognostic subgroups of T-PLL, that will inform future investigations into the biology and treatment of this disease. Methods: We retrospectively evaluated all patients diagnosed with T-PLL at 15 academic cancer centers throughout the USA between 2000-2023 using the recent TPLL-ISG staging and response criteria with overall response rate (ORR) defined as CR and PR. Overall survival (OS) and progression-free survival (PFS) were assessed using Kaplan-Meier methods and cox proportional hazard models. Single-cell RNA sequencing (scRNAseq) was performed using the standard 10X Genomics platform. Results: 377 patients, with a median follow-up time of 29 months (range: 0-196) were evaluated. The median age at diagnosis was 64 and 51% were male. In evaluated patients (n=223), TCL1A was positive by cytogenetics or FISH in 82%. 61% of patients had CD4+CD8- T-PLL, 11% of patients had CD4-CD8+ T-PLL, and 24% of patients had CD4+CD8+ T-PLL, with 4% unknown. 175 patients (46.4%) had known nodal involvement at diagnosis identified by PET or CT scan. Among treated patients (n=342, 91%), using TPLL-ISG criteria, the ORR to any frontline treatment was 67% (49% CR, 18% PR). Median OS and PFS was 19 months and 10 months in responding patients from the start of treatment initiation. For those treated with frontline alemtuzumab (n=250), the ORR was 74% (58% CR), with a median OS and PFS of 18 and 12 months. 20 patients (5%) were treated with a combination of alemtuzumab/pentostatin frontline with an ORR of 85% (70% CR), which was superior to alemtuzumab alone (ORR 74%, 58% CR). Patients that had frontline chemotherapy (excluding pentostatin, n=48) had a worse ORR of 35% (15% CR) (p<0.001), and a worse PFS of 4 months (p=0.002), when compared to those who received alemtuzumab. Among patients in 1st CR/PR (n=226), 44% (n=99) received an allograft and had an improved 3-year OS of 50% vs 17%, (HR=0.67, 95%CI 0.48-0.93), and 50% improvement in PFS (HR 0.48, 0.33-0.68) compared to those who did not receive an allograft. For patients that received second line treatment (n=176, 52%), re-treatment with alemtuzumab (n=33) produced a 46% ORR (21% CR). Other active second-line treatments included: pentostatin (n=23; 44% ORR, 17% CR), ruxolitinib-based regimens (n=4; 25% ORR, 0% CR), venetoclax-based regimens (n=13; 39% ORR, 8% CR), bendamustine (n=10; 30% ORR, 0% CR), and nelarabine (n=4; 75% ORR, 50% CR). In subgroup survival analysis, TCL1A+ patients had a worse OS and PFS when compared to TCL1A- patients (23 months vs 43 months; p=0.02), and (14 months vs 24 months; p=0.02) respectively, with HR 1.58 (1.08, 2.31) (p=0.02) for OS and HR 1.62 (1.09-2.40) (p=0.02) for PFS. Furthermore, CD4- T-PLL had worse OS (16 months vs 25 months) when compared to CD4+ patients [HR 1.57 (1.08, 2.27), p=0.02]. Single cell RNA seq in 13 patients, including 3 TCL1A- patients, with a total of 66,269 T-PLL cells, demonstrated a unique RNA signature between the CD4+/- and TCL1A+/- patients, suggesting these represent unique molecular subtypes of T-PLL. Conclusions: In this large, multi-center study of T-PLL, frontline treatment with a combination of alemtuzumab/pentostatin improved response rates and OS. Further, among patients who attained a CR, allograft improved OS & PFS vs no allograft. In relapsed T-PLL, retreatment with alemtuzumab had a high ORR, and we report significant activity of multiple novel/alternative agents with the largest reported numbers to date. Intriguingly, TCL1A+, and CD4- T- PLL had worse OS/PFS, and scRNAseq confirmed unique molecular signatures in these populations, suggesting these represent novel molecular subtypes of T-PLL with prognostic significance. These studies form the foundation for future, targeted, therapeutic studies in this rare, aggressive disease with few treatment options.

Abstract Little is known about risk factors for central nervous system (CNS) relapse in mature T-cell and natural killer cell neoplasms (MTNKNs). We aimed to describe the clinical epidemiology of CNS relapse in patients with MTNKN and developed the CNS relapse In T-cell lymphoma Index (CITI) to predict patients at the highest risk of CNS relapse. We reviewed data from 135 patients with MTNKN and CNS relapse from 19 North American institutions. After exclusion of leukemic and most cutaneous forms of MTNKNs, patients were pooled with non-CNS relapse control patients from a single institution to create a CNS relapse–enriched training set. Using a complete case analysis (n = 182), including 91 with CNS relapse, we applied a least absolute shrinkage and selection operator Cox regression model to select weighted clinicopathologic variables for the CITI score, which we validated in an external cohort from the Swedish Lymphoma Registry (n = 566). CNS relapse was most frequently observed in patients with peripheral T-cell lymphoma, not otherwise specified (25%). Median time to CNS relapse and median overall survival after CNS relapse were 8.0 and 4.7 months, respectively. We calculated unique CITI risk scores for individual training set patients and stratified them into risk terciles. Validation set patients with low-risk (n = 158) and high-risk (n = 188) CITI scores had a 10-year cumulative risk of CNS relapse of 2.2% and 13.4%, respectively (hazard ratio, 5.24; 95% confidence interval, 1.50-18.26; P = .018). We developed an open-access web-based CITI calculator (https://redcap.link/citicalc) to provide an easy tool for clinical practice. The CITI score is a validated model to predict patients with MTNKN at the highest risk of developing CNS relapse.