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Background: Tumor mutational burden (TMB), defined as the number of nonsynonymous mutations per megabase (Mb) in the coding regions of a tumor genome, has been associated with improved response to immune checkpoint blockade treatments and more broadly with overall survival (OS) in many cancers. Limited prior studies have found that TMB is higher in diffuse large B-cell lymphoma (DLBCL) compared to many other cancers. However, only two studies have evaluated TMB and prognosis in newly diagnosed DLBCL patients. The prognostic role of TMB in diffuse large B-cell lymphoma (DLBCL) remains unclear as prior studies have been limited to panel sequencing of cancer genes and/or lacked matched germline-tumor samples for filtering. Methods: We characterized TMB from whole exome sequencing (WES) in newly diagnosed DLBCL patients with matched diagnostic tumor-normal samples prior to treatment with standard immunochemotherapy (IC). Tumor DNA was extracted from formalin-fixed, paraffin embedded tissue sections and germline DNA from peripheral blood. We evaluated the association between TMB and event-free (EFS) and OS using Cox regression adjusted for the international prognostic index (IPI) and other factors including cell of origin (COO), MYC double hit (DH) with BLC2 or BCL6 by FISH, and TP53 mutation status. EFS and OS were defined as time from diagnosis to earliest of treatment failure (EFS only), death, or last follow-up; EFS at 24 months (EFS24) was also modeled as a marker of early aggressive DLBCL. An optimal high/low TMB cutpoint was determined based on EFS using maximally selected rank statistics; sensitivity analyses used an 20/80 percentile to define the threshold. We also evaluated the association of driver tumor mutational load (driverTML) with EFS and OS, defined as the total number of mutations in 292 DLBCL driver genes. Results: In the analysis cohort of 394 DLBCL patients, the median age at diagnosis was 65 years (interquartile range: 56-73), 43% were female, 62.2% had IPI 0-2, and 57.4% germinal center B-cell COO. MYC was DH in 7.5% and TP53 was mutated in 16.2% of patients. Through a median follow-up of 7.5 years, there were 141 events and 122 deaths. EFS24 was achieved in 75.1% of the cohort; 5-year EFS was 69% (95% CI 64-74%) and 5-year OS was 75% (95% CI 71-80%). Median TMB in our cohort of DLBCL patients was 3.6 mutations/Mb, which was the fifth highest compared with 32 cancers in The Cancer Genome Atlas. As a continuous variable, increasing TMB (mutation/Mb) was associated with superior EFS (HR=0.89, 95% CI 0.81-0.98) and OS (HR=0.89, 95% CI 0.81-0.99) after adjustment for IPI. Spline analyses confirmed linear associations of TMB with EFS and OS. The optimal modeled cutpoint based on EFS was 4.5 mutations/Mb, with 31% classified as high TMB (>4.5). No significant ( P >.05) differences were observed between high and low TMB patients with clinical (i.e., age, sex, IPI category) or molecular (cell of origin, MYC DH, TP53 mutated) factors. In Cox regression, high-TMB was significantly protective for EFS and for OS compared to low-TMB after adjustment for each clinical factor ( Figure 1), with simultaneous adjustment for all these factors associated with superior EFS (HR=0.52, 95% CI 0.33-0.84) and OS (HR=0.59, 95% CI 0.36-1.00). TMB (high/low) combined with IPI (0-2, 3-5) was significantly ( P =.001) associated with EFS in Kaplan-Meier analysis ( Figure 2). Among patients with IPI 3-5, high TMB was significantly associated with superior EFS (HR=0.47, 95% CI 0.27-0.81) and OS (HR=0.57, 95% CI 0.33-0.99). Among patients with IPI 0-2, we also observed longer EFS (HR=0.62, 95% CI 0.34-1.11) and OS (HR=0.62, 95% CI 0.32-1.20) in high TMB patients, although the associations were not statistically significant ( P >.05). In sensitivity analyses, a 20/80 percentile TMB threshold found similar results for EFS (HR=0.64, 95% CI 0.41-1.03) and OS (HR=0.69, 95% CI 0.42-1.12) as in our main analyses. TMB and driverTML were significantly correlated ( R=0.65, P <10 -16) and we found similar effect sizes for EFS (HR=0.45, 95% CI 0.22-0.91) and OS (HR=0.55, 95% 0.27-1.13) as in our main analyses. Conclusions: In a large and well-defined cohort of IC treated DLBCL patients, we found DLBCL patients with higher TMB had superior EFS and OS after adjustment for other clinical and molecular prognostic factors, and the prognostic association for TMB was robust to threshold and gene set.

Background: Primary central nervous system lymphoma (PCNSL) is a rare form of non-Hodgkin lymphoma with two-year overall survival (OS) rates of 66-70% reported in prospective clinical trials. Induction therapy with high-dose methotrexate (HD-MTX) followed by consolidation has become the mainstay of treatment, however, there are few contemporary and robust prognostication indices widely available for clinical use. Some of the most used indices were developed prior to the routine use of rituximab and include the International Extranodal Lymphoma Study Group (IELSG; 1980-1999), Memorial Sloan-Kettering Cancer Center (MSKCC; 1983-2003), Nottingham/Barcelona (NB; 1986-2001), and Taipei Score (TS; 2003-2015). Herein, we describe a contemporary comparison of clinical prognostication indices using a single-center cohort of PCNSL patients treated at the Mayo Clinic. Methods: Patients with a diagnosis of PCNSL who received HD-MTX as part of induction therapy at Mayo Clinic between October 2010 and June 2022 were identified and retrospectively reviewed. Patients with prior or concurrent systemic lymphoma were excluded. Primary endpoints were progression-free survival (PFS) defined as time from diagnosis to relapse, progression, or death due to any cause; and OS defined as time from diagnosis to death due to any cause. PFS and OS were evaluated using Kaplan-Meier curves and compared by risk scores using a log-rank test. The association between baseline characteristics and survival outcome were assessed in univariate Cox regression models. Any characteristics showing significant (p-value <0.05) association with outcome were combined using a multivariate Cox regression model. All characteristics that maintained significant association with outcome were combined into a new prognostic model. We compared the performance of each prognostic index model using Harrell's C (HC). Results: A total of 148 patients were identified (50.7% female) with median age at diagnosis of 66 years (range 29-85), with 48 patients (32.4%) age >70 (Table 1). Most had multifocal disease (60.1%) and deep brain involvement (67.6%) at diagnosis with elevated CSF protein (58.1%) but no documented CSF involvement (93.9%). In total, 117 patients (79.1%) received methotrexate, rituximab, and temozolomide (MRT) induction therapy, and the remaining 31 patients (20.9%) received methotrexate and rituximab (MR) induction therapy with various consolidation strategies. The median follow-up for all patients was 4.5 years and the two-year OS was 79% (95% CI: 73-86%). This cohort was stratified using previously published prognostication indices (Table 1). Upon analysis, PFS was not accurately predicted using the IELSG (score 4-5: HR 0.7 (CI 0.3-2.0); HC 0.6), MSKCC (3: 1.3 (0.4-4.0); 0.5), NB (3: 0.9 (0.4-2.5); 0.6), or TS (3: 0.9 (0.1-7.2); 0.5) prognostication indices. Furthermore, OS was not accurately predicted using the IELSG (4-5: 1.5 (0.6-4.0); 0.6), MSKCC (3: 1.2 (0.5-3.2); 0.6), NB (3: 1.2 (0.5-3.2); 0.6), or TS (3: 1.3 (0.2-9.8); 0.6) prognostication indices. Upon multivariate analysis, no variables listed in Table 1 were associated with PFS within this cohort. The two variables predicting a worsened OS were an ECOG performance status of 2 or more (1.9 (1.01-3.6)) and an MR induction regimen instead of MRT (2.1 (1.05-4.3)) (Figure 1). The two-year OS with no risk factors was 86.1% (95% CI: 78.8-94.1%), one risk factor was 75.7% (95% CI: 63.6-90.1%), and two risk factors was 61% (95% CI: 43-86%) (Figure 1). Conclusions: This study reports overall improved outcomes in patients with PCNSL compared to prior prospective and retrospective cohorts, likely in part due to treatment advances and supportive care strategies. This single-center, retrospective cohort of rituximab-exposed patients with PCNSL were not well prognosticated using previously published indices, indicating that further study and more sophisticated approaches to prognostication are warranted. Although multivariate analysis did not demonstrate any variables associated with PFS, it did demonstrate an inferior OS with a performance score of 2 or more and in patients treated with MR rather than MRT.

Background: Primary central nervous system lymphoma (PCNSL) is a rare form of non-Hodgkin lymphoma with historically poor outcomes. Induction therapy with high-dose methotrexate (HD-MTX)-based regimens followed by consolidation with autologous stem cell transplant (auto-SCT) has become the mainstay of treatment with overall response rates (ORR) of 69-87% and two-year overall survival (OS) of 66-70% reported in prospective clinical trials. Limited data are available regarding a maintenance approach with single-agent HD-MTX, particularly in patients who are not auto-SCT candidates. Herein, we describe a comparison of outcomes in patients with PCNSL who underwent HD-MTX-based induction followed by either HD-MTX maintenance or auto-SCT consolidation at Mayo Clinic, Rochester. Methods: Patients with a diagnosis of PCNSL who received HD-MTX as part of induction therapy at Mayo Clinic between October 2010 and June 2022 were identified. Patients with prior or concurrent diagnosis of systemic lymphoma were excluded. Primary endpoints were progression-free survival (PFS) defined as time from post-induction treatment initiation to relapse, progression, or death due to any cause; and OS defined as time from post-induction treatment initiation to death due to any cause. We compared baseline characteristics by post-induction therapy using descriptive statistics. The primary endpoints PFS and OS were evaluated using Kaplan-Meier curves and compared by risk scores using a log-rank test. Results: A total of 148 patients were identified (51% female, 95% white) with median age at diagnosis of 66 years (range 29-85), with 48 patients (32%) age > 70. Most patients had multifocal disease (n=89, 60%) and deep brain involvement (n=100, 70%) at diagnosis. Few had vitreoretinal (n=15, 10%) or CSF involvement (n=9, 6%) at diagnosis. Using the Memorial Sloan Kettering (MSKCC) prognostic score for PCNSL, 35 patients (26%) scored class 3 (poor prognosis), 85 (62%) scored class 2, and 17 (12%) scored class 1. In total, 117 patients (79%) received methotrexate, rituximab, and temozolomide (MRT) induction therapy, and the remaining 31 patients (21%) received methotrexate and rituximab (MR) induction therapy (Table 1). A total of 70 patients (47%) underwent consolidation with auto-SCT and 37 patients (25%) received maintenance methotrexate. The patients who received maintenance methotrexate had higher median age of 72 versus 62 years, higher proportion of patients older than 70 (54% versus 16%, p<0.001), higher proportion of MSKCC prognostic score class 3 patients (33% versus 17%, p=0.026), and trend towards higher proportion of patients ECOG 2 or higher (41% versus 29%, p=0.109). A higher proportion of patients who underwent auto-SCT received MRT (vs MR) induction (n=64, 91%) compared to those who received maintenance methotrexate (n=24, 65%, p=0.004) (Table 1). The median follow-up for all patients was 4.5 years. At 1-, 3-, and 5-years post-induction treatment initiation, the PFS in the auto-SCT cohort was 85.8% (95% CI 77.7-94.9), 81.0% (95% CI 72.0-91.0), and 74.6% (95% CI 63.3-87.9), respectively; and the PFS in the HD-MTX maintenance cohort was 88.6% (95% CI 78.7-99.8), 72.6% (95% CI 58.8-89.8), and 72.6% (95% CI 58.8-89.8), respectively. At the same time points, the OS in the auto-SCT cohort was 94.0% (95% CI 88.4-99.9), 81.3% (95% CI 71.8-92.0), and 76.0% (95% CI 65.0-89.0), respectively; and the OS in the HD-MTX maintenance cohort was 94.3% (95% CI 86.9-100.0), 87.5% (76.8-99.8%), and 82.4% (69.0-98.4), respectively. Overall, there was no significant difference in PFS (p=0.64) or OS (p=0.95) based on post-induction treatment (Figure 1). Conclusions: Our study demonstrates comparable outcomes in PCNSL between a post-induction treatment approach with maintenance HD-MTX and consolidation auto-SCT, even though baseline characteristics indicate that patients who went on to receive auto-SCT were younger and had overall better performance status. This suggests that maintenance HD-MTX is a reasonable, time-limited strategy for patients with PCNSL responding to initial induction therapy, particularly in patients who are not candidates for auto-SCT.

Background: High Grade B cell Lymphoma (HGBL) with MYC and BCL2 and/or BCL6 rearrangements(R) was introduced as an entity in 2016 by the WHO revised 4 th edition. In 2022, both the WHO 5 th edition (beta version) and the International Consensus Classification (ICC) separated DHL- BCL2 (+/- BCL6-R)from DHL- BCL6 given differences in biology . However, while the ICC has maintainedDHL- BCL6 as a provisional entity, the WHO has removed the category, thus removing the requirement to FISH for BCL6-R in this setting. Clinical data on DHL- BCL6 is much more limited, as these cases represent only 10-20% of DHL and have been combined with BCL2-R cases in prior studies. Outcomes are variable in retrospective studies with no consistent data on prognosis or optimal therapeutic strategies. By retaining the category of DHL-BCL6 as a provisional entity, the ICC emphasized the need for further, multicenter, prospective studies evaluating the clinical and biological features of this disease. We herein report a comprehensive comparison of clinical characteristics and outcomes in patients with DHL- BCL6 compared to diffuse large B-cell lymphoma (DLBCL), not otherwise specified (NOS); DLBCL with MYC rearrangement only; DHL- BCL2; and HGBL, NOS in a large, multicenter, prospective cohort of patients from Lymphoma Epidemiology of Outcomes (LEO). Methods: Adult patients with newly diagnosed large B-cell or HGBL were enrolled within 6 months of diagnosis at one the 8 LEO cohort academic medical centers in the US between 2015 and 2020. Baseline characteristics were abstracted at the time of diagnosis per protocol. Based on FISH data patients were further sub mgrouped into DLBCL, NOS (without MYC rearrangement); MYC-R DLBCL, NOS; HGBL, NOS; DHL- BCL2 and DHL- BCL6. Event-free survival (EFS) was defined as the time from diagnosis until progression/relapse, retreatment, or death. Overall survival (OS) was defined as the time from diagnosis until death due to any cause. Results: A total of 1526 eligible patients were identified during this time period. All FISH data was available at the time of diagnosis and the choice of treatment was based on physician discretion. Median age at diagnosis was 63 years (IQR 53-72), with 148 (10%) patients in the AYA category, and 128 (8%) patients > 80 years. 58% (891) were male, 11% self identified as Hispanic or Latino, and 7% as Black/African American. The median diagnosis to treatment interval (DTI) was 20 days (IQR 12-32), and 33% had DTI < 14 days. The FISH-based subgroups were MYC-negative DLBCL, NOS (N=1146, 75%), MYC-R DLBCL,NOS 227 (N = 96, 6%), DHL- BCL2 (N=154, 10%), DHL- BCL6 (N=38, 3%), and HGBL, NOS (N=92, 6%). When available, COO by Hans algorithm was 92% GCB in DHL- BCL2 and 50% GCB in DHL- BCL6. Clinical characteristics can be found in the table. At a median follow-up of 49 months (IQR 36-67), 490 patients (32%) had an event and 356 patients (23%) died. EFS at 24 months (EFS24) was 75% (95% CI: 73-77). Patients with DHL- BCL6 were younger at diagnosis (median 60 years), had more extranodal site involvement (40%), more often stage III/IV disease (70%), and more often treated with a higher intensity regimen than R-CHOP (69%) compared to DLBCL,NOS and MYC-R DLBCL. DHL- BCL6 also had fewer patients that were males (47%), with DTI <=14 days (33%), NCCN IPI ≥ 4 (45%), elevated LDH (53%) than HGBL, NOS and DHL- BCL2. The 2-year EFS and OS rates were noted to be significantly better in the DHL- BCL6 (EFS 79%, 95% CI: 67-93; OS 92%, 95% CI: 84-100) as compared to DHL- BCL2 (EFS 58%, 95% CI: 50-66; OS 70%, 95% CI 63 - 78) and HGBL, NOS (EFS 74%, 95% CI: 65-84; OS 74%, 95% CI: 65-84 ), (Figure 1) but were comparable to that of DLBCL, NOS (EFS 78%, 95% CI: 76-81; OS 87%, 95% CI: 86-89). Conclusions: Our data support separating DHL- BCL6 from DHL -BCL2 as these patients form a unique subgroup with some clinical characteristics comparable to both DLBCL, NOS as well as HGBL, NOS and DHL- BCL2 subtypes. In this cohort, clinical outcomes are more comparable to DLBCL, NOS than DHL- BCL2 or HGBCL, NOS. More frequent use of intensive chemotherapy in DHL- BCL6 compared with DLBCL may account for this finding, although larger multicenter studies are needed. Our results support continued identification of DHL- BCL6 in the clinical setting to better understand optimal therapy and biology of this cohort.

Introduction: Histologic transformation (HT) from follicular lymphoma (FL) to an aggressive lymphoma is infrequent but has unfavorable outcomes. Sarkozy et al. (J Clin Oncol, 2019) reported that approximately half of FL-related deaths within the first decade of diagnosis occurred following HT. Our recent analysis showed heterogeneous outcomes with median overall survival (OS) of 61 months (Day et al., ASH, 2022). Prognostic tools post HT would be clinically useful but development has been limited by small cohort sizes. Factors previously associated with outcomes following HT have included age, time to progression, prior therapy, anthracycline exposure, and early HT. Utilizing the Lymphoma Epidemiology of Outcomes (LEO) Consortium of Real World Evidence (CReWE), we describe patterns of care and evaluate other prognostic factors following HT. Methods: This multicenter observational cohort consists of prospectively enrolled patients in the LEO Cohort, and patients with HT retrospectively identified at LEO centers. Patients diagnosed with biopsy proven grade 1-3A FL at diagnosis, and a subsequent biopsy showing HT to an aggressive lymphoma (FL grade 3B, diffuse large B cell lymphoma [DLBCL], or high-grade B cell lymphoma [HGBCL]) between 2002-2022, were eligible for the study. Patients with a component of FL grade 3B, DLBCL, or HGBCL at diagnosis were excluded. HGBCL was defined as double or triple hit or another aggressive subtype. OS was defined as the time from HT until death from any cause and calculated via Kaplan-Meier. Associations between clinical factors at time of HT and/or diagnosis and OS were evaluated using Cox models. Cause of death was evaluated using a competing risk approach. Results: Overall, 328 patients were confirmed with HT during the study period, 41% were female, and the median age at HT was 63 years (interquartile range [IQR] 56-70). The median time from diagnosis to transformation (TDT) was 35 months (IQR 12-66). At HT, 88% had advanced stage disease (III-IV) and LDH was elevated in 49%, while few patients exhibited B symptoms (5%) and ECOG performance status was >2 in 9%. 23% did not receive systemic therapy prior to HT. For those with prior therapy, the median time from prior therapy to HT was 15 months (IQR 7-39). The most frequent treatment regimens following HT were CD20-CHOP (42%), followed by platinum-based salvage therapy (20%), R-EPOCH (10%), CD20-Benda (8%), R-Mono (4%), and R-Gem-Ox (3%). 50 (15%) patients underwent consolidation with autologous stem cell transplant, 3 underwent allogeneic transplant (30 platinum-based, 15 CD20-CHOP, 5 R-EPOCH, 3 Other), and 2 received CAR T-cell therapy (Figure 1). After median follow-up of 85 months from HT, 170 patients had died; 5-year OS was 52% and median OS was 65 months (95% CI: 55-107). Among 160 patient deaths, cause was most often lymphoma-related (progression, n=107 [63%]; therapy-related, n=14 [7%]) compared to non-lymphoma (n=20, 13%) or missing/unknown causes (n=29, 17%). Clinical factors at the time of HT that were associated with worse OS include: ECOG PS >2, age ≥70, IPI 3-5, and shorter TDT (<24 months), hemoglobin <10 g/dl and elevated LDH. A transformation to HGBCL was also associated with inferior OS (Table 1). OS did not significantly differ by gender, BMI, stage, presence of B-symptoms, absolute lymphocyte count, number of extranodal groups, presence of bulky disease at HT, or response to prior FL treatment. Factors at the time of FL diagnosis that were associated with decreased OS after HT included FLIPI score 3-5 (high risk), FLIPI 2 (moderate risk), and FL grade 3A at diagnosis. Exposure to any systemic therapy for FL prior to HT was associated with shorter OS, with the worst outcomes in patients receiving an anthracycline prior to HT. POD24 to frontline immunochemotherapy was associated with inferior OS after HT (Table 1). Conclusions: Patterns of care in Transformed FL are heterogeneous and vary greatly in intensity. These data confirm previous reports that age, early HT, and any systemic therapies prior to HT are negative prognostic indicators for OS. At HT elevated LDH, low hemoglobin, POD24 status, poor performance status, and HT to HGBCL were associated with poor outcomes following HT. These data provide a basis for future prognostic indices to identify patients with highest risk of lymphoma related mortality for whom study of novel treatments is greatly needed.

Background Central nervous system (CNS) involvement is a rare complication (<5% of cases) of mantle cell lymphoma (MCL) and is associated with poor outcomes, highlighting the need for novel treatment approaches. We report the outcomes of a large cohort of patients (pts) with CNS MCL from Mayo Clinic and Memorial Sloan Kettering Cancer Center (MSKCC). Methods MCL pts with CNS involvement seen at Mayo Clinic and MSKCC between 1/2000-1/2021 were included. CNS involvement was defined by histologically confirmed CNS MCL, CSF analysis demonstrating lymphoma cells, and/or neuroimaging findings compatible with CNS lymphoma. Medical records were reviewed for baseline characteristics, treatment, and outcomes. First-line MCL chemotherapy was categorized into higher intensity chemotherapy (i.e., anthracycline-based +/- high-dose cytarabine), moderate intensity chemotherapy (i.e., bendamustine-based regimens or single agent chemotherapy), and other. CNS treatment regimens were categorized as intrathecal (IT) therapy alone, systemic therapy (with CNS penetration such as IV cytarabine or IV methotrexate) with/without IT therapy, regimens with Bruton's tyrosine kinase inhibitors (BTKi), chimeric antigen receptor T cell (CAR-T) therapy, or radiation alone. Kaplan-Meier method was used for time to event analysis. Forest plots were developed using univariable Cox proportional hazards models. Results Seventy patients were included in the cohort, 34 from MSKCC and 36 from Mayo Clinic. Median age at MCL diagnosis was 65 years (range 56-72) and 52 were male (74%). MIPI score was available in 60 pts: low (n=10, 17%), intermediate (n=20, 33%), and high (n=30, 50%) risk. First line therapy included: higher intensity chemotherapy (n=42, 60%), moderate intensity chemotherapy (n=25, 36%) and other (n=3, 4%). Twenty-five (36%) pts underwent autologous hematopoietic cell transplantation in CR1. Median time from initial MCL diagnosis to CNS involvement was 24 months (m) (range 0-167). Four (6%) pts had CNS involvement at initial diagnosis. Abnormal CNS imaging was reported in 53 (76%) pts: leptomeningeal (n=37), leptomeningeal and parenchymal (n=4), parenchymal (n=8), orbital (n=4). The most common regimen following CNS diagnosis was systemic therapy with or without IT therapy (n=34, 54%) followed by treatment including BTKi (n=13, 21%), IT alone (n=10, 16%), radiation alone (n=3, 5%), and treatment including CAR-T (n=3, 5%). Three patients elected hospice care and four patients had missing/unknown CNS treatment. The overall CNS response to therapy was available in 54 patients: CR in 22 (41%) pts, PR in 8 (15%), SD in 11 (20%), and PD in 13 (24%) pts. Of the 70 patients, 63 died. Median follow up was 6.9 years (range: 1.6-11.2) from initial MCL diagnosis and 2.1 years from CNS diagnosis (range: 0.4-7.9). Median OS from MCL diagnosis was 3.4 years (95% CI: 2.4-4.6). In univariable Cox models, sex, stage, performance status, Ki67, or first line systemic chemotherapy type were not significantly associated with OS from MCL diagnosis. Low risk MIPI score (score < 5.7) was associated with favorable OS (HR 0.31, 94% CI: 0.12-0.77; p value 0.01) compared to high risk. First-line treatment and treatment intensity were not associated with a significant difference in OS. Median PFS for the first CNS-directed therapy was 2.4 m (95% CI: 1.7-4.3). Cause of death was disease-related in a majority (n=49, 78%) of pts and therapy-related in 10% (n=6). The remaining 8 deaths had cause of death reported as missing or other (13%). Median OS from CNS involvement was 5.1 m (95% CI: 3.3-10.0) (Figure 1). When assessing OS from time of CNS diagnosis, treatment regimens incorporating BTK inhibitors were associated with a more favorable OS compared to systemic therapy +/- IT therapy (HR=0.37, 95% CI: 0.16-0.89, p value=0.03) (Figure 2). Conclusions Our dual center series confirms patients with CNS involvement by MCL have poor outcomes. When evaluating OS from the time of CNS diagnosis, novel therapies, including BTKi and CAR-T, may be more effective than CNS-penetrant chemotherapy for treatment of CNS relapse suggesting newer therapeutic approaches are required to improve outcomes.

Aim: Patients with R/R LBCL after first-line treatment have poor prognosis. Multiple novel therapies have been approved for R/R LBCL in recent years, but CIT regimens are still commonly used. This study evaluated the effectiveness of CIT and novel therapies in 2L+ in patients with R/R LBCL and the association between patient clinical characteristics and real-world outcomes. Methods: This was a multi-site retrospective observational study of patients aged ≥18 years with R/R LBCL in the Lymphoma Epidemiology of Outcomes (LEO) Consortium of Real-World Evidence (CReWE) cohort (patients followed from 1/1/2015 to 2/15/2023) who were treated with CIT or novel therapy in 2L+. CIT regimens included salvage/palliative chemotherapy, lenalidomide, rituximab, or obinutuzumab, used alone or in combination. Novel therapies included polatuzumab vedotin plus bendamustine and rituximab or variations thereof (i.e., pola-based regimen), tafasitamab plus lenalidomide or variations thereof (tafa-based regimen), and loncastuximab tesirine (lonca). Patients' demographic and clinical characteristics were assessed from the first confirmed R/R disease diagnosis and initiation of 2L+ therapy. When multiple lines of therapy (LOTs) were eligible for inclusion in the analysis, one was randomly selected as the index LOT. Real-world outcomes, determined by investigators at each clinical site, including overall response rate (ORR), complete response (CR) rate, duration of response (DOR), duration of complete response (DOCR), progression-free survival (PFS), and overall survival (OS) were described for all patients in each treatment group and for the subgroup of patients with prior chimeric antigen receptor (CAR) T-cell therapy. Multivariable Cox Proportional Hazards models were used to assess associations between select patient clinical characteristics and real-world outcomes. Results: The study population included patients treated with CIT (N=653), pola-based regimen (N=116), tafa-based regimen (N=55), and lonca (N=42) ( Figure 1A). The median (m) age at date of index treatment initiation across groups ranged from 63 to 74 years. Across groups, most patients had primary refractory disease-i.e., were refractory to the first LOT (69.5% CIT vs. 73.3% pola vs. 58.2% tafa vs. 71.4% lonca), whereas variable proportions had one prior LOT (65.5% vs. 17.2% vs. 43.6% vs. 7.1%) and prior CAR T-cell therapy (5.1% vs. 43.1% vs. 32.7% vs. 47.6%). In the CIT group, ORR was 33.8%, 15.5% of patients achieved CR, mPFS (95% CI) was 1.9 (1.7, 2.1) months, and mOS was 9.1 (8.1, 10.5) months. In the pola group, ORR was 42.2%, 24.1% of patients achieved CR, mPFS was 2.5 (2, 3.2) months and mOS was 7.8 (6.4, 11.8) months. In the tafa group, ORR was 25.5%, 14.5% of patients achieved CR, mPFS was 2.7 (2.1, 4.2) months, and mOS was 8 (5.3, 12.7) months. In the lonca group, ORR was 40.5%, 21.4% of patients achieved CR, mPFS was 3 (2.1, 5.1) months, and mOS was 4.7 (3.7, 10.8) months. Demographics and outcomes for all patients and those who received prior CAR T-cell therapy are summarized in Figure 1A. In the multivariable Cox regression analysis, International Prognostic Index (IPI) risk score ≥3, CIT as the index treatment type, and primary refractory status were significantly associated with time from response to progression/death (P<0.05; Figure 1B). IPI risk score ≥3, CIT as the index treatment type, and primary refractory status were significantly associated with worse PFS. IPI risk ≥3, ≥3 prior LOTs, and primary refractory status were significantly associated with OS. Conclusion: In this large clinical cohort of patients with R/R LBCL with high proportions having primary refractory disease, all common treatments were associated with modest ORR/CR and poor OS. Receiving CIT treatments, higher IPI score, primary refractory status, and higher number of prior LOTs were significantly associated with poor clinical outcomes. A study with larger sample size and longer follow-up may be warranted to further understand the clinical effectiveness of novel treatments. Thus, despite the availability of novel treatments during the study period, these findings highlight the need for more effective treatment alternatives beyond currently available options to improve outcomes.

Introduction The Ki-67 index has been previously shown to be prognostic, wherein the cut-off of 30% was associated with inferior survival outcomes (Determann O et al, Blood 2008) in newly diagnosed MCL patients (pts). However, this cut-off determination was made in pts treated with CHOP/R-CHOP as the first-line treatment, controlled only for MIPI, and predates the advent of novel agents. Short diagnosis to treatment interval (DTI ≤ 14 days) was recently shown to be prognostic in newly diagnosed MCL but its association with Ki-67 is unknown. We sought to determine the optimal Ki-67 cut-off in MCL and its prognostic relevance in the modern era. Methods This is a pooled analysis of 2 large datasets, one prospective (CALGB 50403) and one retrospective (MCL real world study [MCL-RWS]). CALGB is now part of the Alliance for Clinical Trials in Oncology. CALGB 50403 is a phase II randomized study wherein newly diagnosed MCL pts received intensive induction chemoimmunotherapy (IIC) followed by autologous transplant, and posttransplant rituximab. The MCL-RWS included adult pts (≥18 years [yrs]) with MCL treated from 2000 to 2017 at 12 participating US sites. Pts from sites in the MCL-RWS that enrolled on CALGB 50403 were excluded. Ki-67 was scored by central review in 10% increments in the CALGB 50403 and per institutional standard in the MCL-RWS. We assessed Ki-67 as a continuous variable and used a restricted quadratic spline fit to find an optimal cut-off. We looked at the associations between Ki-67 and other known/ established MCL prognostic markers including MIPI and DTI. The outcome parameters were PFS and OS. Time-to-event endpoints were evaluated by Kaplan-Meier and Cox proportional hazard methods. Results Among the 793 pts (n=666, MCL-RWS and n=127, CALGB 50403) in the pooled analysis, Ki-67 was available in 385 pts (311 from MCL-RWS and 74 from CALGB 50403). The median OS (mOS) and PFS (mPFS) in the entire cohort (n=793) was 11.8 years and 4.7 years, respectively. The two groups (gps), those with and without Ki-67 data, were well balanced including MIPI and DTI. The median age was 62 yrs (range, 32-88), 81% males, 94% with ECOG performance status (PS) 0-1 and 84% with stage 4. We found a Ki-67 cut-off of 50% to be optimal as the relative hazard of death rises after 50%. Pts in the Ki-67 >50% gp had significantly higher proportion with short DTI (36% vs 17%, p<0.001), ECOG PS ≥2 (12% vs 5%, p=0.02), elevated LDH (58% vs 39%, p=0.005), and MIPI ≥6.2 (38% vs 20%, p=0.007) compared to Ki-67 of ≤50%. Ki-67 >50% was associated with significantly inferior PFS with a hazard ratio (HR) of 2.10 (95%CI 1.50-2.92) compared to Ki-67 ≤50% with a mPFS of 2.1 vs 5.3 yrs, respectively, regardless of the age (young [≤65 yrs], 2.6 vs 5.3 yrs or old [>65 yrs], 1.1 vs 5.4 yrs) or receipt of IIC (2.2 vs 5.9 yrs). Figure 1 shows the statistically significant difference in PFS between the Ki-67 gps of ≤10%, >10% to <30%, ≥30 to ≤50%, and >50%. Ki-67 >50% remained prognostic for PFS in multivariable analysis (MVA) after adjusting for significant variables in univariable analysis (UVA) including short DTI, ECOG PS ≥2, stage 4, elevated LDH, and MIPI ≥6.2 with adjusted HR (aHR) 2.19, 95%CI 1.38-3.48, p <0.001. Ki-67 >50% was associated with significantly inferior OS with a HR of 2.10 (95%CI 1.33-3.32) compared to Ki-67 ≤50% with a mOS of 9.4 yrs vs not reached (NR), respectively, regardless of the age or receipt of IIC. Figure 2 shows the statistically significant difference in OS between the Ki-67 gps of ≤10%, >10% to <30%, ≥30 to ≤50%, and >50%. Ki-67 >50% was not prognostic for OS in MVA after adjusting for significant variables in the UVA (MIPI and sex), aHR 1.79, 95% CI 0.92-3.49, p=0.08. Similar findings were seen in multivariable analysis with Ki-67 >30%, which showed no prognostic significance (aHR 1.46, 95%CI 0.82-2.58, p=0.19). Because of disparate datasets, we performed sensitivity analysis looking at the prognostic relevance of in individual datasets (CALGB 50403 and MCL-RWS) and found Ki67 >50% was prognostic for PFS and OS in both of the datasets consistent with the primary analysis. Conclusions This study evaluating the optimal Ki-67 cut off for pts with newly diagnosed MCL in the modern era found that Ki-67 > 50% was prognostic for PFS but not OS in MVA. A potential reason for the lack of prognostic relevance for OS in this more recent dataset is the availability of effective options at relapse. We also found that short DTI was associated with high Ki-67 gp which is a novel finding.

Novel targeted therapies (small molecule inhibitors, antibody–drug conjugates, and CD19-directed therapies) have changed the treatment landscape of relapsed/refractory B-cell lymphomas. Bruton’s tyrosine kinase (BTK) inhibitors continue to evolve in the management of mantle cell lymphoma (MCL), in both the relapsed/refractory and the frontline setting. Anti-CD19 CAR T-cell therapies are now effective and approved treatment options for relapsed/refractory follicular lymphoma (FL), diffuse large B-cell lymphoma (DLBCL), and MCL. Bispecific T-cell engagers represent a novel immunotherapeutic approach for relapsed FL and DLBCL after multiple lines of therapies, including prior CAR T-cell therapy. These NCCN Guideline Insights highlight the significant updates to the NCCN Guidelines for B-Cell Lymphomas for the treatment of FL, DLBCL, and MCL.

SummaryMantle cell lymphoma (MCL) is clinically and biologically heterogeneous. While various prognostic features have been proposed, none currently impact therapy selection, particularly in older patients, for whom treatment is primarily dictated by age and comorbidities. Herein, we undertook a comprehensive comparison of clinicopathological features in a cohort of patients 60 years and older, uniformly treated with bendamustine and rituximab, with a median survival of >8 years. The strongest prognostic indicators in this cohort were a high‐risk call by a simplified MCL international prognostic index (s‐MIPI) (HR: 3.32, 95% CI: 1.65–6.68 compared to low risk), a high‐risk call by MCL35 (HR: 10.34, 95% CI: 2.37–45.20 compared to low risk) and blastoid cytology (HR: 4.21, 95% CR: 1.92–9.22 compared to classic). Patients called high risk by both the s‐MIPI and MCL35 had the most dismal prognosis (HR: 11.58, 95% CI: 4.10–32.72), while those with high risk by either had a moderate but clinically relevant prognosis (HR: 2.95, 95% CI: 1.49–5.82). A robust assay to assess proliferation, such as MCL35, along with stringent guidelines for cytological evaluation of MCL, in combination with MIPI, may be a strong path to risk‐stratify older MCL patients in future clinical trials.