International Prognostic Score for Nodular Lymphocyte-Predominant Hodgkin Lymphoma.

PURPOSE: Nodular lymphocyte-predominant Hodgkin lymphoma (NLPHL) is a rare cancer, and large international cooperative efforts are needed to evaluate the significance of clinical risk factors and immunoarchitectural patterns (IAPs) for all stages of pediatric and adult patients with NLPHL. METHODS: Thirty-eight institutions participated in the Global nLPHL One Working Group retrospective study of NLPHL cases from 1992 to 2021. We measured progression-free survival (PFS), overall survival (OS), transformation rate, and lymphoma-specific death rate. We performed uni- and multivariable (MVA) Cox regression stratified by management to select factors for the lymphocyte-predominant international prognostic score (LP-IPS) validated by five-fold cross-validation. RESULTS: We identified 2,243 patients with a median age of 37 years (IQR, 23-51). The median follow-up was 6.3 years (IQR, 3.4-10.8). Most had stage I to II (72.9%) and few B symptoms (9.9%) or splenic involvement (5.4%). IAP was scored for 916 (40.8%). Frontline management included chemotherapy alone (32.4%), combined modality therapy (30.5%), radiotherapy alone (24.0%), observation after excision (4.6%), rituximab alone (4.0%), active surveillance (3.4%), and rituximab and radiotherapy (1.1%). The PFS, OS, transformation, and lymphoma-specific death rates at 10 years were 70.8%, 91.6%, 4.8%, and 3.3%, respectively. On MVA, IAPs were not associated with PFS or OS, but IAP E had higher risk of transformation (hazard ratio [HR], 1.81; P < .05). We developed the LP-IPS with 1 point each for age ≥45 years, stage III-IV, hemoglobin <10.5 g/dL, and splenic involvement. Increasing LP-IPS was significantly associated with worse PFS (HR, 1.52) and OS (HR, 2.31) and increased risk of lymphoma-specific death (HR, 2.63) and transformation (HR, 1.41). CONCLUSION: In this comprehensive study of all ages of patients with NLPHL, we develop the LP-IPS to identify high-risk patients and inform upcoming prospective clinical trials evaluating de-escalation of therapy for patients with low LP-IPS scores (<2).

Impact of Race and Social Determinants of Health on Outcomes in Patients with Aggressive B-cell nHL Treated with CAR-T.

Healthcare disparities driven by multiple social, economic, and/or environmental factors lead to inequalities in health outcomes. CAR-T cell immunotherapy is an effective therapy for relapsed/refractory B-cell non-Hodgkin lymphoma (r/r B-NHL). However, data are limited on the impact of the convergence of race and social determinants of health on outcomes for patients treated with CAR-T therapy. We examined the impact of interactions between race and insurance type on health care utilization and outcomes in patients treated with CAR-T for aggressive B-NHL. Adult patients with r/r B-NHL treated with CD19 CAR-T were identified between 2015 and 2021 across 13 US academic centers. Insurance type, demographic and clinical data were collected and analyzed via Chi-squared and Kaplan-Meier analysis. Cox multivariable regression (MVA) was used to determine the impact of race/ethnicity and other variables on survival. 466 adult patients were included in our analysis. Median follow-up after CAR-T was 12.7 months. Median progression free survival (mPFS) was longer for Caucasians (11.5 months) than for African Americans (3.5 months, HR 1.56 [1.03-2.4], p=0.04) or Asians (2.7 months, HR 1.7 [1.02-2.67], p=0.04). Differences in median overall survival (mOS) were not significant. For Medicare (n=206) vs Medicaid (n=33) vs private insurance (n=219) vs self-pay (n=7): mPFS was 15.9 vs 4.2 vs 6.0 vs 0.9 months (p<0.001) and mOS was 31.2 vs 12.8 vs 21.5 vs 3.2 months (p<0.001), respectively. Collectively, our multi-center retrospective analysis showed that race and insurance status can impact outcomes for patients treated with CAR-T cell therapy.

Integrative analysis of clinicopathological features defines novel prognostic models for mantle cell lymphoma in the immunochemotherapy era: a report from The North American Mantle Cell Lymphoma Consortium.

BACKGROUND: Patients with mantle cell lymphoma (MCL) exhibit a wide variation in clinical presentation and outcome. However, the commonly used prognostic models are outdated and inadequate to address the needs of the current multidisciplinary management of this disease. This study aims to investigate the clinical and pathological features of MCL in the immunochemotherapy era and improve the prognostic models for a more accurate prediction of patient outcomes. METHODS: The North American Mantle Cell Lymphoma Project is a multi-institutional collaboration of 23 institutions across North America to evaluate and refine prognosticators for front-line therapy. A total of 586 MCL cases diagnosed between 2000 and 2012 are included in this study. A comprehensive retrospective analysis was performed on the clinicopathological features, treatment approaches, and outcomes of these cases. The establishment of novel prognostic models was based on in-depth examination of baseline parameters, and subsequent validation in an independent cohort of MCL cases. RESULTS: In front-line strategies, the use of hematopoietic stem cell transplantation was the most significant parameter affecting outcomes, for both overall survival (OS, p < 0.0001) and progression-free survival (PFS, p < 0.0001). P53 positive expression was the most significant pathological parameter correlating with inferior outcomes (p < 0.0001 for OS and p = 0.0021 for PFS). Based on the baseline risk factor profile, we developed a set of prognostic models incorporating clinical, laboratory, and pathological parameters that are specifically tailored for various applications. These models, when tested in the validation cohort, exhibited strong predictive power for survival and showed a stratification resembling the training cohort. CONCLUSIONS: The outcome of patients with MCL has markedly improved over the past two decades, and further enhancement is anticipated with the evolution of clinical management. The innovative prognostic models developed in this study would serve as a valuable tool to guide the selection of more suitable treatment strategies for patients with MCL.

Outcomes of patients with secondary central nervous system lymphoma following CAR T-cell therapy: a multicenter cohort study.

Chimeric antigen receptor T-cell therapy (CAR-T) has been successful in treating relapsed/refractory B-cell lymphomas. However, its role in the treatment of diseases involving the central nervous system (CNS) is not well studied. We performed a multicenter retrospective cohort study to evaluate the outcomes of patients with secondary CNS lymphoma (SCNSL) who received CAR-T. Eligibility required active CNSL at the time of apheresis. The objectives included evaluation of overall survival (OS), progression-free survival (PFS), identification of predictors of complete response (CR) post-CAR-T, and assessment of risk factors for cytokine release syndrome (CRS) and immune effector cell-associated neurotoxicity syndrome (ICANS). Sixty-one patients were included in the analysis. The overall response rate was 68% with a CR rate of 57%. In the multivariable analysis, patients who experienced any grade CRS had higher odds of achieving CR (OR = 3.9, 95% CI = 1.01-15.39, p = 0.047). The median PFS was 3.3 months (95% CI = 2.6-6.0 months) with 6- and 12-month PFS rates of 35% and 16%, respectively. The median OS was 7.6 months (95% CI = 5.0-13.5 months) with 6- and 12-month OS rates of 59% and 41%, respectively. Any grade CRS and ICANS were 70% (n = 43) and 57% (n = 34), respectively with grade ≥ 3 CRS and ICANS rates of 16% and 44%. Factors associated with increased risk of CRS and ICANS included receiving axi-cel or having leptomeningeal ± parenchymal + CNS involvement, respectively. Despite achieving high response rates, most patients experience early relapse or death following CAR-T in SCNSL. The current study provides a benchmark for future trials exploring novel therapeutic options in SCNSL.

Population Pharmacokinetics and Pharmacodynamics of Carfilzomib in Combination with Rituximab, Ifosfamide, Carboplatin, and Etoposide in Adult Patients with Relapsed/Refractory Diffuse Large B Cell Lymphoma.

BACKGROUND: In patients with relapsed/refractory (R/R) diffuse large B-cell lymphoma (DLBCL), salvage chemotherapy regimens (e.g., rituximab, ifosfamide, carboplatin, and etoposide, R-ICE) yield poor outcomes. Carfilzomib, an irreversible proteasome inhibitor, can overcome acquired rituximab-chemotherapy resistance and, when combined with R-ICE, improves outcomes in patients with R/R DLBCL. OBJECTIVE: This analysis aimed to develop a population pharmacokinetic/pharmacodynamic (PK/PD) model for carfilzomib in R/R DLBCL patients. PATIENTS AND METHODS: In a single-center, open-label, prospective phase 1 study, patients received carfilzomib (10, 15, or 20 mg/m2) on days 1, 2, 8, and 9, and standard doses of R-ICE on days 3-6 every 21 days (maximum of three cycles). Carfilzomib plasma concentrations up to 24 h postinfusion were measured by liquid chromatography coupled with tandem mass spectrometry. Proteasome activity (PD biomarker) in peripheral blood mononuclear cells was assessed on days 1-2 with sparse sampling. PK/PD models were developed using NONMEM v7.4.1 interfaced with Finch Studio v1.1.0 and PsN v4.7.0. Model selection was guided by objective function value, goodness-of-fit, and visual predictive checks. Stepwise covariate modeling was used for covariate selection. RESULTS: Twenty-eight patients were enrolled in the PK/PD analysis, from whom 217 PK samples and 127 PD samples were included. Carfilzomib PK was best described by a two-compartment model with linear disposition (typical total clearance of 133 L/h). Proteasome activity was best characterized using a turnover model with irreversible inactivation. All parameters were estimated with good precision. No statistically significant covariates were identified. CONCLUSIONS: A validated population-based PK/PD model of carfilzomib was developed successfully. Further research is needed to identify sources of variability in response to treatment with carfilzomib in combination with R-ICE. CLINICAL TRIAL REGISTRATION: ClinicalTrials.gov identifier number NCT01959698.

Impact of cumulative dose of brentuximab vedotin on outcomes of frontline therapy for advanced-stage Hodgkin lymphoma.

In the pivotal study ECHELON-1, brentuximab vedotin (BV), doxorubicin, vinblastine, and dacarbazine (A + AVD) demonstrated superior efficacy compared with bleomycin + AVD for the treatment of advanced-stage classic Hodgkin lymphoma (cHL). However, there are minimal available data regarding the frequency of dose reductions or omission of BV during curative therapy and the potential impact on patient outcomes. In a real-world analysis, we retrospectively reviewed the characteristics and outcomes of 179 patients with stage III or IV cHL treated with frontline A + AVD from January 2010 to April 2022. Treatment consisted of up to 1.2 mg/kg of BV and standard dose AVD IV on days 1 and 15 of each 28-day cycle for up to 6 cycles. At the time of treatment, the median patient age was 37 years, and a high-risk International Prognostic Score was observed in 46% of patients. Overall, 91% of patients received 6 cycles of AVD; 55% of patients did not receive the intended cumulative dose of BV (CDB); 28% of patients received two-thirds or less than the planned CDB. At a median follow-up time of 27.4 months (95% confidence interval [CI], 24.8-29), the median progression-free survival (PFS) was not reached, and the 12-month PFS was 90.3% (95% CI, 85.9-95.0). The impact of CDB on PFS was not significant (P = .15), nor was high CDB significantly associated with increased adverse events. In real-world experience, A + AVD is a highly effective treatment for patients with advanced-stage cHL, including for patients with prominent dose reductions of BV.

Impact of detectable monoclonal protein at diagnosis on outcomes in marginal zone lymphoma: a multicenter cohort study.

Given the paucity of data surrounding the prognostic relevance of monoclonal paraprotein (M-protein) in marginal zone lymphoma (MZL), we sought to evaluate the impact of detecting M-protein at diagnosis on outcomes in patients with MZL in a large retrospective cohort. The study included 547 patients receiving first-line therapy for MZL. M-protein was detectable at diagnosis in 173 (32%) patients. There was no significant difference in the time from diagnosis to initiation of any therapy (systemic and local) between the M-protein and no M-protein groups. Patients with M-protein at diagnosis had significantly inferior progression-free survival (PFS) compared with those without M-protein at diagnosis. After adjusting for factors associated with inferior PFS in univariate models, presence of M-protein remained significantly associated with inferior PFS (hazard ratio, 1.74; 95% confidence interval, 1.20-2.54; P = .004). We observed no significant difference in the PFS based on the type or quantity of M-protein at diagnosis. There were differential outcomes in PFS based on the first-line therapy in patients with M-protein at diagnosis, in that, those receiving immunochemotherapy had better outcomes compared with those receiving rituximab monotherapy. The cumulative incidence of relapse in stage 1 disease among the recipients of local therapy was higher in the presence of M-protein; however, this did not reach statistical significance. We found that M-protein at diagnosis was associated with a higher risk of histologic transformation. Because the PFS difference related to presence of M-protein was not observed in patients receiving bendamustine and rituximab, immunochemotherapy may be a preferred approach over rituximab monotherapy in this group and needs to be explored further.

Impact of early relapse within 24 months after first-line systemic therapy (POD24) on outcomes in patients with marginal zone lymphoma: A US multisite study.

Progression of disease within 24 months (POD24) from diagnosis in marginal zone lymphoma (MZL) was shown to portend poor outcomes in prior studies. However, many patients with MZL do not require immediate therapy, and the time from diagnosis-to-treatment interval can be highly variable with no universal criteria to initiate systemic therapy. Hence, we sought to evaluate the prognostic relevance of early relapse or progression within 24 months from systemic therapy initiation in a large US cohort. The primary objective was to evaluate the overall survival (OS) in the two groups. The secondary objective included the evaluation of factors predictive of POD24 and the assessment of cumulative incidence of histologic transformation (HT) in POD24 versus non-POD24 groups. The study included 524 patients with 143 (27%) in POD24 and 381 (73%) in non-POD24 groups. Patients with POD24 had inferior OS compared to those without POD24, regardless of the type of systemic therapy received (rituximab monotherapy or immunochemotherapy) at diagnosis. After adjusting for factors associated with inferior OS in the univariate Cox model, POD24 remained associated with significantly inferior OS (HR = 2.50, 95% CI = 1.53-4.09, p = 0.0003) in multivariable analysis. The presence of monoclonal protein at diagnosis and those who received first-line rituximab monotherapy had higher odds of POD24 on logistic regression analysis. Patients with POD24 had a significantly higher risk for HT compared to those without POD24. POD24 in MZL might be associated with adverse biology and could be used as an additional information point in clinical trials and investigated as a marker for worse prognosis.

High-grade B-cell lymphoma, not otherwise specified: a multi-institutional retrospective study.

In this multi-institutional retrospective study, we examined the characteristics and outcomes of 160 patients with high-grade B-cell lymphoma, not otherwise specified (HGBL-NOS)-a rare category defined by high-grade morphologic features and lack of MYC rearrangements with BCL2 and/or BCL6 rearrangements ("double hit"). Our results show that HGBL-NOS tumors are heterogeneous: 83% of patients had a germinal center B-cell immunophenotype, 37% a dual-expressor immunophenotype (MYC and BCL2 expression), 28% MYC rearrangement, 13% BCL2 rearrangement, and 11% BCL6 rearrangement. Most patients presented with stage IV disease, a high serum lactate dehydrogenase, and other high-risk clinical factors. Most frequent first-line regimens included dose-adjusted cyclophosphamide, doxorubicin, vincristine, and etoposide, with rituximab and prednisone (DA-EPOCH-R; 43%); rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisone (R-CHOP; 33%); or other intensive chemotherapy programs. We found no significant differences in the rates of complete response (CR), progression-free survival (PFS), or overall survival (OS) between these chemotherapy regimens. CR was attained by 69% of patients. PFS at 2 years was 55.2% and OS was 68.1%. In a multivariable model, the main prognostic factors for PFS and OS were poor performance status, lactate dehydrogenase >3 × upper limit of normal, and a dual-expressor immunophenotype. Age >60 years or presence of MYC rearrangement were not prognostic, but patients with TP53 alterations had a dismal PFS. Presence of MYC rearrangement was not predictive of better PFS in patients treated with DA-EPOCH-R vs R-CHOP. Improvements in the diagnostic criteria and therapeutic approaches beyond dose-intense chemotherapy are needed to overcome the unfavorable prognosis of patients with HGBL-NOS.

Pharmacologic targeting of Nedd8-activating enzyme reinvigorates T-cell responses in lymphoid neoplasia.

Neddylation is a sequential enzyme-based process which regulates the function of E3 Cullin-RING ligase (CRL) and thus degradation of substrate proteins. Here we show that CD8+ T cells are a direct target for therapeutically relevant anti-lymphoma activity of pevonedistat, a Nedd8-activating enzyme (NAE) inhibitor. Pevonedistat-treated patient-derived CD8+ T cells upregulated TNFα and IFNγ and exhibited enhanced cytotoxicity. Pevonedistat induced CD8+ T-cell inflamed microenvironment and delayed tumor progression in A20 syngeneic lymphoma model. This anti-tumor effect lessened when CD8+ T cells lost the ability to engage tumors through MHC class I interactions, achieved either through CD8+ T-cell depletion or genetic knockout of B2M. Meanwhile, loss of UBE2M in tumor did not alter efficacy of pevonedistat. Concurrent blockade of NAE and PD-1 led to enhanced tumor immune infiltration, T-cell activation and chemokine expression and synergistically restricted tumor growth. shRNA-mediated knockdown of HIF-1α, a CRL substrate, abrogated the in vitro effects of pevonedistat, suggesting that NAE inhibition modulates T-cell function in HIF-1α-dependent manner. scRNA-Seq-based clinical analyses in lymphoma patients receiving pevonedistat therapy demonstrated upregulation of interferon response signatures in immune cells. Thus, targeting NAE enhances the inflammatory T-cell state, providing rationale for checkpoint blockade-based combination therapy.

Effect of cumulative dose of brentuximab vedotin maintenance in relapsed/refractory classical Hodgkin lymphoma after autologous stem cell transplant: an analysis of real-world outcomes.

Sixteen cycles of Brentuximab vedotin (BV) after autologous stem cell transplant (ASCT) in high-risk relapsed/refractory classical Hodgkin lymphoma demonstrated an improved 2-year progression-free survival (PFS) over placebo. However, most patients are unable to complete all 16 cycles at full dose due to toxicity. This retrospective, multicenter study investigated the effect of cumulative maintenance BV dose on 2-year PFS. Data were collected from patients who received at least one cycle of BV maintenance after ASCT with one of the following high-risk features: primary refractory disease (PRD), extra-nodal disease (END), or relapse <12 months (RL<12) from the end of frontline therapy. Cohort 1 had patients with >75% of the planned total cumulative dose, cohort 2 with 51-75% of dose, and cohort 3 with ≤50% of dose. The primary outcome was 2-year PFS. A total of 118 patients were included. Fifty percent had PRD, 29% had RL<12, and 39% had END. Forty-four percent of patients had prior exposure to BV and 65% were in complete remission before ASCT. Only 14% of patients received the full planned BV dose. Sixty-one percent of patients discontinued maintenance early and majority of those (72%) were due to toxicity. The 2-year PFS for the entire population was 80.7%. The 2-year PFS was 89.2% for cohort 1 (n=39), 86.2% for cohort 2 (n=33), and 77.9% for cohort 3 (n=46) (P=0.70). These data are reassuring for patients who require dose reductions or discontinuation to manage toxicity.

AMG176, an MCL-1 inhibitor, is active in pre-clinical models of aggressive B-cell lymphomas.

Upregulation of the anti-apoptotic protein MCL-1 has been implicated in chemotherapy resistance and poor clinical outcomes in B-cell lymphoma (BCL). We report the activity of AMG176, a direct, selective MCL-1 inhibitor, in preclinical models of BCL. A panel of cell lines representing diffuse large B-cell lymphoma (DLBCL), double-hit lymphoma (DHL) and Burkitt's lymphoma (BL) was selected. AMG176 induced apoptotic cell death in a dose- and time-dependent manner in all BCL cell lines. Baseline MCL-1 expression was not predictive of response. AMG176 exhibited impressive synergy with venetoclax and chemotherapeutic agents, less so with proteasomal inhibitors, and antagonism with anti-CD20 monoclonal antibodies. The activity of AMG176 could not be confirmed in murine models of BCL. Combination therapy targeting MCL-1 and BCL-2 may provide an alternative therapeutic approach in BCL, however optimal patient selection will remain the key to obtaining high response rates and tolerability.

Older patients with primary central nervous system lymphoma: Survival and prognostication across 20 U.S. cancer centers.

There is a paucity of large-scale data delineating outcomes and prognostication of older patients with primary central nervous system lymphoma (PCNSL). We retrospectively analyzed 539 newly-diagnosed PCNSL patients ages ≥60 years across 20 U.S. academic centers. The median age was 70 years (range 60-88); at least one geriatric syndrome was present in 46%; the median Cumulative Index Ratings Scale-Geriatrics (CIRS-G) score was 6 (range, 0-27); and 36% had impairment in activities of daily living (ADL). The most common induction regimens were high-dose methotrexate (HD-MTX) ± rituximab; methotrexate, temozolomide, rituximab (MTR); and rituximab, methotrexate, procarbazine, vincristine (R-MPV). Overall, 70% of patients achieved remission, with 14% undergoing consolidative autologous stem cell transplant (ASCT) and 24% receiving maintenance. With 58-month median follow-up, median progression-free survival (PFS) and overall survival (OS) were 17 months (95% CI 13-22 months) and 43 months (95% CI 31-56 months), respectively. Three-year PFS and OS were highest with MTR (55% and 74%, respectively). With single-agent methotrexate ± rituximab, 3-year PFS and OS were 30% (p = .0002) and 47% (p = .0072). On multivariate analysis, increasing age at diagnosis and Cooperative Oncology Group (ECOG) performance status (PS) was associated with inferior PFS; age, hypoalbuminemia, higher CIRS-G score, and ECOG PS adversely affected OS. Among patients receiving maintenance, 3-year PFS was 65% versus 45% without maintenance (p = 0.02), with 3-year OS of 84% versus 61%, respectively (p = .0003). Altogether, outcomes in older PCNSL patients appeared optimized with HD-MTX combination induction regimens and maintenance therapy. Furthermore, several prognostic factors, including geriatric measures, were associated with inferior outcomes.

EBV-positive PCNSL in older patients: incidence, characteristics, tumor pathology, and outcomes across a large multicenter cohort.

The objective of this multicenter retrospective study was to examine the incidence, patient characteristics, pathology, and outcomes associated with Epstein-Barr virus (EBV)-related CNS lymphoma (CNSL) in older patients. Among 309 CNSL patients aged ≥60, 11.7% had EBV + tumors of which 72.2% were solid organ transplant (SOT)-related post-transplant lymphoproliferative disorders (PTLD). Younger age, SOT or autoimmune disease, and immunosuppressive treatment correlated highly with EBV-positivity. EBV + tumors were associated with absent C-MYC and BCL6 expression. EBV + PTLD was more likely to be associated with the absence of CD5 expression. EBV + non-PTLD had better median OS (not reached) compared to EBV + PTLD (10.8 months) and EBV-negative patients (43 months). Multivariable Cox regression analysis showed that age, performance status, and PTLD were negative predictors of OS. EBV status and immunosuppressive treatment were not correlated with OS. Our findings merit further investigation of EBV + PCNSL tumors and EBV-directed therapies.

Is local review of positron emission tomography scans sufficient in diffuse large B-cell lymphoma clinical trials? A CALGB 50303 analysis.

BACKGROUND: Quantitative methods of Fluorodeoxyglucose Positron Emission Tomography (FDG-PET) interpretation, including the percent change in FDG uptake from baseline (ΔSUV), are under investigation in lymphoma to overcome challenges associated with visual scoring systems (VSS) such as the Deauville 5-point scale (5-PS). METHODS: In CALGB 50303, patients with DLBCL received frontline R-CHOP or DA-EPOCH-R, and although there were no significant associations between interim PET responses assessed centrally after cycle 2 (iPET) using 5-PS with progression-free survival (PFS) or overall survival (OS), there were significant associations between central determinations of iPET ∆SUV with PFS/OS. In this patient cohort, we retrospectively compared local vs central iPET readings and evaluated associations between local imaging data and survival outcomes. RESULTS: Agreement between local and central review was moderate (kappa = 0.53) for VSS and high (kappa = 0.81) for ∆SUV categories (<66% vs. ≥66%). ∆SUV ≥66% at iPET was significantly associated with PFS (p = 0.03) and OS (p = 0.002), but VSS was not. Associations with PFS/OS when applying local review vs central review were comparable. CONCLUSIONS: These data suggest that local PET interpretation for response determination may be acceptable in clinical trials. Our findings also highlight limitations of VSS and call for incorporation of more objective measures of response assessment in clinical trials.

A multicenter analysis of the outcomes with venetoclax in patients with relapsed mantle cell lymphoma.

To report the activity of venetoclax in patients with relapsed mantle cell lymphoma (MCL), we identified 81 patients treated with venetoclax monotherapy (n = 50, 62%) or in combination with a Bruton tyrosine kinase inhibitor (BTKi) (n = 16, 20%), an anti-CD20 monoclonal antibody (n = 11, 14%), or other active agents at 12 US academic medical centers. Patients had high-risk disease features including Ki67 >30% (61%), blastoid/pleomorphic histology (29%), complex karyotype (34%), and TP53 alterations (49%), and received a median of 3 prior treatments including BTKis in 91%. Venetoclax alone or in combination resulted in an overall response rate (ORR) of 40% and median progression-free (PFS) and overall survival (OS) of 3.7 and 12.5 months, respectively. The receipt of ≤3 prior treatments was associated with higher odds of response to venetoclax in a univariable analysis. In a multivariable analysis, having a high-risk Mantle Cell Lymphoma International Prognostic Index score before receiving venetoclax and disease relapse or progression within 24 months of diagnosis were associated with inferior OS whereas the use of venetoclax in combination was associated with superior OS. Although most patients (61%) had low risk for tumor lysis syndrome (TLS), 12.3% of patients developed TLS despite the implementation of several mitigation strategies. In conclusion, venetoclax resulted in good ORR but short PFS in patients with MCL who are at high risk, and may have a better role in earlier lines of treatment and/or in conation with other active agents. TLS remains an important risk in patients with MCL who initiate treatment with venetoclax.