Johnston, Patrick B.

e19552 Background: Leukemic involvement (LI) in diffuse large B cell lymphoma (L-DLBCL) is very rare and has been sparsely reported. We report our experience with this entity in a large academic multi-center setting. Methods: Medical records of patients with DLBCL who received care at Mayo Clinic between 1/2003 and 6/2020 were reviewed. DLBCL patients with LI were identified. LI was defined as increased white blood cell counts and the presence of clonal B cells on peripheral blood flow-cytometry. Kaplan-Meier method was used for survival analysis. Results: Twenty patients with L-DLBCL were identified with a median follow-up of 32.5 months (CI95%, 32.5-NR). Median age at initial diagnosis was 62 (45-80) years. 60% (12/20) were male; 90% (18/20) were Caucasian. Pathologically, 90% (18/20) had DLBCL and 10% (2/20) had high-grade B cell lymphoma (HGBCL) with intermediate features between DLBCL and Burkitt lymphoma. By Hans criteria, 58% (11/19) had germinal center B-cell DLBCL (GCB-DLBCL) and 42% (8/19) had non-germinal center B-cell DLBCL (non-GCB-DLBCL). 40% (8/20) had transformed DLBCL (t-DLBCL); 36% (5/14) had double-hit lymphoma (DHL) by FISH analysis. LI was present in 55% (11/20) at initial diagnosis and 45% (9/20) at relapse. Median WBC was 39.5/ul (range, 4.3-121) with median absolute lymphocyte count of 25 k/ul (range, 0.7-117). Immunophenotypically, the leukemic lymphoma cells expressed CD19, CD20, and CD79a. Bone marrow involvement and pancytopenia were documented in all patients with a median bone marrow cellularity of 80%. Other extranodal sites of involvement with LI included spleen (65%;13/20), liver (20%;4/20), breast and soft tissue (20%;4/20), bladder or kidneys (10%;2/20), skeleton (10%;2/20), and myocardium (5%;1/20). 65% (13/20) had B-symptoms. All patients had LDH elevation (UNL 222 U/L) with a median of 2125 U/L (range, 308-10,760). 45% (5/11) of patients with LI at initial diagnosis had CNS involvement on relapse/progression. All patients with LI at initial diagnosis received anthracycline-based chemoimmunotherapy with or without CNS prophylaxis. Patients with LI at relapse had had a median of 2 prior treatments (range, 1-5) before LI. Median overall survival (OS) for the whole group was 9 months (CI 95%; 5.8-11.8). There were no long-term survivors. Median progression free survival after LI was 4.7 months (CI95%; 0.8-7.6) in the newly diagnosed group and 3 months (CI95%; 0.9-20) in the relapsed group. 90% (18/20) died due to their progressive disease. Cell of origin, DHL status, or newly diagnosed vs. relapsed status did not have a significant impact on OS in patients with L-DLBCL. Conclusions: Leukemic involvement at any time during the course of DLBCL is associated with poor prognosis. It also appears to be a major risk factor for CNS relapse. It is most frequently associated with DHL and t-DLBCL. Novel therapeutic approaches at the time of initial therapy need to be developed for L-DLBCL.

e19547 Background: Primary cutaneous diffuse large B-cell lymphoma, leg type (PCDLBCL, LT) is a rare, aggressive lymphoma characterized by skin involvement predominantly in the lower extremities, and is associated with an inferior prognosis compared to other primary cutaneous B-cell lymphomas. Immunochemotherapy with or without involved-field radiation therapy (IFRT) is considered standard, front-line therapy. Interestingly, over-expression of PD-L1/PD-L2 has been shown in a high proportion of PCDLBCL, LT cases, but efficacy of immune checkpoint inhibitors (ICI) in relapsed/refractory, PCDLBCL, LT has not been thoroughly studied. Therefore, we describe the outcomes of 1) immunochemotherapy with and without IFRT as front-line treatment of PCDLBCL, LT, and 2) ICIs in the relapsed/refractory setting. Methods: We conducted a retrospective cohort study of patients diagnosed with PCDLBCL, LT seen at Mayo Clinic from January 1, 2000 to December 31, 2020. Using the Kaplan-Meier method, we calculated progression-free survival (PFS), duration of response (DOR), and overall survival (OS) in patients who received front-line R-CHOP with and without IFRT, and salvage ICI therapy for relapsed/refractory disease. Results: A total of 28 patients with PCDLBCL, LT were identified. The median age at diagnosis was 71.6 years (range 48.0-91.7), 50% (N = 14) were male, and 78.6% (N = 22) had disease involvement of the lower extremities at diagnosis. For front-line treatment, 31.2% (N = 9) received R-CHOP with IFRT, and 31.2% (N = 9) received R-CHOP without IFRT. The median PFS in patients treated with R-CHOP plus IFRT was 41.8 months [95% CI: 30.2-69.6] compared to 13.7 months [95% CI: 10.7-27.7; p= 0.01] in those treated with R-CHOP without IFRT. The median OS in patients treated with R-CHOP plus IFRT was 74.7 months [95% CI: 53.0-108.6] compared to 38.2 months [95% CI: 26.0-80.4; p= 0.14] in those treated with R-CHOP without IFRT. Patient and disease characteristics were similar among these two groups. ICIs were used in 17.9% (N = 5) of patients with relapsed/refractory, PCDLBCL, LT, and these patients had received a median of three (range 2-10) prior systemic therapies. The overall response rate was 60% as three patients treated with ICIs achieved a complete response, and the other two patients showed no clinical response. The median DOR from ICIs was 23.0 months [95% CI: 3.6-26.0]. The median PFS from ICI therapy was 10.2 months [95% CI: 3.6 – not reached]. Only one of the five patients was noted to have a mild side effect from ICI treatment (elevated alkaline phosphatase, grade 1). Conclusions: R-CHOP with IFRT was associated with a longer median PFS compared to R-CHOP without IFRT as front-line therapy for PCDLBCL, LT. Furthermore, ICIs may have a role in treating relapsed/refractory disease as reasonable activity in heavily pre-treated patients and a favorable safety profile were observed in this study. Further studies would be of benefit to confirm our findings.

e19501 Background: The current standard of care for patients with relapsed or refractory (RR) diffuse large B-cell lymphoma (DLBCL) following frontline immunochemotherapy (IC) is salvage therapy, followed by high-dose chemotherapy and autologous stem cell transplant (ASCT) rescue in patients responding to salvage therapy. Time to first relapse (or refractory status) and response to salvage therapy in patients with RR DLBCL may reflect the chemosensitivity of the underlying disease. The aim of this study is to determine whether these factors impact post-ASCT outcomes. Methods: Patients with DLBCL that relapsed after R-CHOP or R-CHOP-like frontline therapy who underwent salvage therapy and ASCT at Mayo Clinic or University of Iowa between 07/2000 and 4/2020 were identified from institutional lymphoma and transplant databases. Clinical characteristics, treatment information, and outcome data were abstracted. Progression-free survival (PFS) and overall survival (OS) from the time of ASCT were analyzed using Kaplan-Meier method and Cox proportional hazards models. Results: A total of 437 patients with RR DLBCL who underwent salvage therapy and ASCT were identified. 280 (64%) were male. Median time from initial diagnosis to 1st relapse/salvage was 1.0 years (range 0.1-16.4). A median of 1 line (range 1-3) of salvage therapy was required. Response prior to ASCT was complete response (CR) in 211 (48%), partial response in 199 (46%), stable disease in 24 (5%), and unknown in 3 (1%) patients. Median age at ASCT was 61 years (range 19-78), and median follow up after ASCT was 8.0 years (95% CI 7.2-8.7). Median PFS and OS was 2.7 (95% CI 1.5-4.3) and 5.4 (4.2-7.4) years, respectively. Time to 1st relapse/salvage (≤1 vs 1-2 vs > 2 years) was not associated with PFS (median 0.8 vs 2.4 vs 4.9 years, p = 0.170) but was associated with OS (2.4 vs 7.4 vs 6.8 years, p = 0.013). Patients who required > 1 line of salvage therapy had significantly inferior PFS (median 0.3 vs 4.5 years, p < 0.001) and OS (0.9 vs 7.4 years, p < 0.001). In addition, patients who failed to achieve a CR prior to ASCT had significantly worse PFS (median 0.8 vs 5.3 years, p < 0.001) and OS (2.7 vs 9.2 years, p < 0.001). In multivariate Cox regression models adjusted for age and sex, time to 1st relapse/salvage was not associated with PFS (p = 0.313) or OS (p = 0.081); however, lines of salvage and response prior to ASCT remain significantly prognostic for PFS ( > 1 line of salvage: HR 2.14, 95% CI 1.59-2.87, p < 0.001; non-CR: HR 1.61, 95% CI 1.26-2.05, p < 0.001) and OS ( > 1 line of salvage: HR 2.25, 95% CI 1.66-3.05, p < 0.001; non-CR: HR 1.63, 95% CI 1.26-2.12, p < 0.001). Conclusions: In patients with RR DLBCL following frontline IC, requiring more than 1 line of salvage therapy and failure to achieve CR are strong independent risk factors for poor PFS and OS after ASCT. Novel therapies such as CAR-T cell therapy should be studied in this population.

7558 Background: A low absolute lymphocyte to monocyte ratio (ALC/AMC) has been found to predict decreased survival in lymphoma patients receiving chemotherapy and stem cell transplant. We report its clinical significance and additional cellular phenotype changes in patients receiving chimeric antigen receptor T-cell (CART) therapy. Methods: Records were reviewed for patients (pts) who received axicabtagene ciloleucel between 6/2016 and 12/2020. Receiver operator curve was generated using nominal logistic regression to predict CR as best response. Survivals were calculated using Kaplan- Meier method. Blood immune phenotype were assayed by multiparametric flow. Principle component analysis (PCA) was performed using ClusterVis. Results: Low ALC/AMC (≤0.8) prior to lymphodepletion (LD) chemotherapy on day -5 was associated with lower CR rate (AUC=0.68, Table). Our cohort of 81 pts had similar baseline characteristics except that noted in Table. Low ALC/AMC ratio is associated with shorter EFS and OS (EFS: 2.6 vs. 6.4 months, P<0.0001; OS: 5.3 months vs. not reached, P=0.0006), respectively. Prognostic association remained significant in multivariate analysis including ASCT, bridging therapy and CRP. Interestingly, compared to the high ALC/AMC group, the low ALC/AMC group had decreased CD8 Tem, increased CD16+CCR2+ monocytes and increased monocytes’ producing IL12, IL-10, and IL-1β (n=26). Unsupervised PCA identified 3 clusters: 1. Low ALC/AMC, all non-CR; 2. High ALC/AMC, some non-CR; 3. High ALC/AMC, all CR. Compared to cluster 1 and 2, cluster 3 had increased CD4 Tnaive, CD8 Tcm and IL-17 producing CD4 T and NK cells. Conclusions: ALC/AMC is a clinically accessible test that is strongly associated with CAR-T response and survival. Immune characterization revealed that the biologic effect is not just associated with cell ratio. Increased inflammation has been found to negatively impact CAR-T response, with some cytokines known to be from the myeloid lineage. We show that CRP is elevated in the low ALC/AMC group with increased cytokine production by monocytes. In addition, presence of T cell subset and IL-17 producing cells, before LD, are associated with clinical response. Further investigation on optimizing host immunity may help improve clinical outcome with CAR-T.[Table: see text]

7555 Background: While CAR-T therapy is not myelo-ablative, patients with aggressive lymphoma treated with CD19 chimeric antigen receptor T cell therapy (CAR-T) are lymphodepleted and have prolonged B cell aplasia. The impact of CAR-T on immunologic protection from vaccine-preventable diseases (and thus the need to revaccinate) is not known. We report the vaccine titers of patients treated with axicabtagene ciloleucel (axi-cel) at Mayo Clinic. Methods: Retrospective chart review of adult lymphoma patients who received axi-cel from 9/2018 to 9/2020 for anti-viral and anti-bacterial titers prior to CAR-T infusion and at month 3 (MO3) post CAR-T. Results: Prior to CAR-T therapy, positive titer rate was highest for tetanus and lowest for Strep pneumoniae (Strep PNA) (Table). Similar trends were seen whether patients had stem cell transplant (ASCT) within 2 years of CAR-T (i.e. within immunization timeframe post ASCT) or not (Table). Compared to patients who had ASCT, those who did not had higher rate of positive titer for Strep PNA and lower rate for hepatitis B, Mumps, and VZV. The same trend for sero-positive rate were observed at MO3 post CAR-T. Patients with IgG<400 mg/dl received IVIG supplement for prophylaxis. Among the 23 patients who received IVIG, variable rate of conversion from negative to positive titers were seen for measles (1/2, 50%), mumps (2/3, 67%), rubella (2/3, 67%), varicella-zoster (VZV, 3/3, 100%), hepatitis A (6/6, 100%), hepatitis B (6/7, 86%) and Strep PNA (0/10, 0%). For patients who did not receive IVIG prophylaxis, there was one loss of seropositivity for Strep PNA (1/4, 25%). Conclusions: The presence of protective vaccine titers is variable for patients receiving CAR-T, regardless of recent ASCT. The loss of protective titers post CART was low. IVIG variably impacted vaccine titer status. Immunization remains important for patients with ASCT prior to CART, without completion of post ASCT immunization protocol. Further study is needed to inform the need for immunization and optimal timing post CART.[Table: see text]

7554 Background: Chimeric antigen receptor T-cell therapy (CAR-T) are commonly administered inpatient due to concern for early onset cytokine release syndrome (CRS), especially with axicabtagene ciloleucel (axi-cel). We report Mayo Clinic Rochester experience for hospital-based outpatient (HBO) management of patients (pts) receiving axi-cel and identify opportunities for improvement. HBO is closely integrated with inpatient practice and includes the same specialty trained clinical team. It is the first point of contact 24/7 for pts and triage evaluations. Lymphodepletion chemotherapy and CAR-T infusion is given on HBO followed by daily monitoring till day 8 and thereafter, as clinically needed until admission criteria is met. Methods: We retrospectively analyzed database of pts who received axi-cel between 1/2018 and 1/2021. After 06/2020, remote patient monitoring (RPM) tools were implemented to collect patient-reported neurologic symptoms and vital signs via bluetooth-enabled devices 4 times daily through month 1. Adverse data trends are addressed by the HBO team. Results: Among 72 recipients, 89% received their cells outpatient; 8% remained outpatient for the entire month. CRS and neurotoxicity incidence were comparable to those reported from CIBMTR. Median time to first admission was 2 days (Table). Use of bridging therapy, increased CRP and LDH were associated with early admission (≤3 days). Median time to tocilizumab, steroid, oxygen support, vasopressor was 4 days after admission. Half of HBO visits required intervention such as blood transfusions, IV medications through the first month. Nine pts had enrolled in RPM to date; with 8 having evaluable data. With 4 scheduled entries/day, a median of 1 entry/day was skipped and 2 entries/day were answered incompletely. An average of 57 additional unscheduled entries were generated per pt. Among a median of 373 (range 91-522) readings per pt over the first month, 4% (2%-20%) of the readings generated alerts. An average of 4 alerts were seen within 48 hours prior to admission. Data including additional subjects will be presented at ASCO meeting. Conclusions: We report a feasible outpatient care model for management of axi-cel recipients with safe outcomes. Clinical characteristics associated with more aggressive disease are associated with likelihood of early admission. Early RPM experience suggest use of digital tools could improve monitoring compliance and may predict evolution to symptoms requiring escalation of care.[Table: see text]

7542 Background: 60-70% of patients with newly diagnosed diffuse large B-cell lymphoma (DLBCL) can be cured with R-CHOP or R-CHOP-like immunochemotherapy. However, patients ≥80 years of age were either excluded or underrepresented in modern DLBCL trials, and their outcomes are understudied. The aim of this study is to define the survival trends and risk factors for inferior survival in older adult patients with DLBCL. Methods: Patients with newly diagnosed DLBCL were identified from the National Cancer Database (2004-2017, representing the rituximab era). Clinical characteristics, treatment, and outcomes were compared between patients ages ≥ 80, 65-79, and < 65 years. The Kaplan-Meier method and Cox proportional hazards model were used for survival analysis. Results: A total of 231,756 patients with newly diagnosed DLBCL were identified; 46,250 (20%) were ≥80 years, 87,702 (38%) were 65-79 years, and 97,904 (42%) were < 65 years. Patients ≥80 years were more likely to have a higher Charlson-Deyo Comorbidity Index score (CDS) (CDS ≥2, 12% vs 11% vs 8%, p = 0.001), less likely to receive systemic chemotherapy (63% vs 83% vs 89%, p < 0.001), and more likely to receive treatment at a non-academic center (71% vs 65% vs 48%, p < 0.001), compared to patients 65-79 and < 65 years, respectively. Median overall survival (OS) was significantly worse for patients ≥80 years compared to patients 65-79 years (11.6 vs 61.0 months, p = 0.001) and patients < 65 years (11.6 vs 178.1 months, p = 0.001). During the study period, the median OS had only minimally improved for patients ≥80 years (10.6 months in 2004-2007 vs 11.5 months in 2008-2011 vs 12.3 months in 2012-2016, p = 0.006). In contrast, the OS improvement appears more meaningful in patients 65-79 years (median in months: 51 vs 61.2 vs 65.9, p = < 0.001) and patients < 65 years (median in years: 14.6 vs 11.3 vs not reached, p < 0.001) in the prespecified intervals (2004-07, 2008-11, and 2012-16). In multivariate analysis, the most substantial risk factor for worse survival in patients ≥80 years was not receiving systemic therapy (hazard ratio [HR] = 3.26, 95%CI = 3.01-3.54, p = 0.001). Other risk factors associated with worse survival included high-risk IPI score (HR = 2.16, 95%CI = 1.96-2.39, p = 0.001), CDS score ≥2 (HR = 1.56, 95%CI = 1.40-1.73, p = 0.001), male sex (HR = 1.16, 95%CI = 1.09-1.24, p = 0.001), B symptoms at diagnosis (HR = 1.16, 95%CI = 1.08-1.25, p = 0.001), and treatment at a non-academic center (HR = 1.1, 95%CI = 1.01-1.20, p = 0.001). Conclusions: Patients ≥ 80 years of age with DLBCL have a significantly inferior survival which has not meaningfully improved in recent years. More than 1/3 of patients ≥ 80 years did not receive systemic therapy. Older adult patients with DLBCL should be assessed for fitness for chemotherapy using validated geriatric assessment tools. Novel therapeutic strategies with favorable safety profiles are urgently needed for this expanding patient population.

7530 Background: Clinical trials of novel salvage therapies (ST) have encouraging outcomes for relapsed/refractory classic Hodgkin lymphoma (R/R cHL) eligible for autologous stem cell transplant (ASCT). In this observational study, we report efficacies and outcomes of different ST in ASCT-eligible R/R cHL. Methods: Consecutive ASCT-eligible R/R cHL pts at 3 Mayo Clinic sites were included. Demographics and clinical variables at relapse were recorded by medical records review. Time to event endpoints were defined from relapse. Univariate associations were confirmed in multivariate models of age, sex, B symptoms, stage, bulky disease (BD, single mass > 6 cm) extra nodal disease (END), primary refractory disease (PRD) and early relapse (ER, within 1 year). Results: From Jan 2008 to May 2020, 207 ASCT-eligible pts with R/R cHL were included. Median age was 33 (24-43) years, 53% were male, 52% had advanced stage, 24% had BD, 36% had B symptoms, 41% had END, 11% had PRD and 43% had ER. All patients received ST and underwent ASCT; 43 (21%) received 2 ST, 14 (7%) 3 ST and 4 (0.5%) received 4 ST. 6 groups of ST were identified: ifosfamide, carboplatin and etoposide (ICE), bendamustine/brentuximab (BBV), brentuximab vedotin (BV), gemcitabine-based therapy (Gem), checkpoint inhibitor (CPI), and others. Table lists response to first line ST. BBV had significantly higher overall response rate (ORR) and complete response (CR) as first ST in univariate and multivariate models. 114 (79%) after ICE, 30 (97%) after BBV, 15 (56%) after BV, 25 (76%) after Gem, 8 (73%) after CPI and 15 (79%) after other ST underwent ASCT. Higher number of pts were bridged to ASCT after BBV than ICE (p<0.01). 110 (53%) went to ASCT in CR, 74 (36%) in partial response (PR) and 11% in progressive disease (PD). 43 received BV maintenance (BVm) after ASCT. Pts going to ASCT in PR or PD had significantly lower progression free survival (PFS) compared to pts in CR (2 yr PFS: 62%, 18% vs 77%, respectively, p<0.0001) in univariate and multivariate models. There was no difference in PFS and overall survival (OS) by type of ST. BVm was associated with higher PFS (HR 0.3 (CI95 0.2-0.8)) and higher number of ST was associated with lower OS (HR 2 (CI95 1.4-3)) in multivariate model (p<0.001). For pts transplanted in CR, there was no significant difference in PFS and OS by type of ST but higher number of ST predicted lower OS (HR 2.4 (CI95 1.2-3.5), p<0.01). Conclusions: Type of ST did not predict survival, response to and number of ST did. For pts with CR, number of ST not type of ST predicted survival. BBV had higher response rates, higher rates of bridge to ASCT, and may be a preferable ST than ICE. Large, randomized trials are needed to evaluate efficacy of BBV compared to ICE.[Table: see text]

7522 Background: Patients with newly diagnoseddiffuse large B-cell lymphoma (DLBCL) who achieve event-free survival at 24 months (EFS24) following immunochemotherapy (IC) have excellent overall survival (OS) similar to that of age- and sex-matched general population. The standard of care for patients with relapsed or refractory (RR) DLBCL following frontline IC is salvage therapy followed by autologous stem cell transplant (ASCT). The goal of this study is to evaluate the role of progression-free survival (PFS) at 24 months (PFS24) as a landmark after ASCT in patients with RR DLBCL. Methods: Patients with RR DLBCL after frontline R-CHOP or R-CHOP-like IC who underwent salvage therapy and ASCT at Mayo Clinic or University of Iowa between 07/2000 and 4/2020 were identified from institutional lymphoma transplant databases. Clinical characteristics, treatment information, and outcome data were abstracted. Post-ASCT PFS, OS, and post-relapse survival (PRS) were plotted by Kaplan-Meier method, and cumulative incidences of relapse vs non-relapse mortality (NRM) and different causes of death were compared accounting for competing events. Statistical analyses were performed in EZR v1.54. Results: A total of 437 patients were identified. Median age at ASCT was 61 years (range 19-78), and 280 (64%) were male. After a median post-ASCT follow up of 8.0 years (95% CI 7.2-8.7), 215 patients had a relapse (or disease progression), 180 within 2 years and 35 after 2 years. For the entire cohort, post-ASCT relapse rate was much higher than NRM rate (48.1 vs 9.1% at 5-year). Median PFS and OS after ASCT was 2.7 and 5.4 years, respectively. Lymphoma was the primary cause of death after ASCT. In contrast, for patients who had achieved PFS24 (n = 220), rates of post-PFS24 relapse and NRM were similar (14.8% and 12.3% at 5-year). Median PFS and OS after achieving PFS24 was 10.0 and 11.5 years, respectively. Lymphoma related and unrelated death rates were similar after achieving PFS24 (Table). For all patients who had a post-ASCT relapse, median PRS was 0.7 years (95% CI 0.5-0.9), and late relapse ( > 2 vs ≤2 years after ASCT) was associated with better PRS (median 2.3 [1.7-4.8] vs 0.5 [0.3-0.7] years, p < 0.001). Conclusions: Post-ASCT PFS24 is an important prognostic predictor of post-ASCT outcomes in patients with RR DLBCL following frontline IC.[Table: see text]

e19527 Background: While extra nodal involvement by MCL is relatively common, involvement of the central nervous system (CNS) is a rare ( < 5% of cases) complication with limited treatment options. We report the outcomes of a large cohort of patients (pts) with CNS MCL. Methods: MCL pts with CNS involvement seen at Mayo Clinic between 1/1/1995-9/16/2020 were identified. 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 outcome. Kaplan-Meier method was used for time to event analysis. Results: Out of 1,753 pts with MCL, 36 (2%) had CNS involvement by MCL. Median age at MCL diagnosis was 64 years (range 36-83) and 26 were male (72%). At MCL diagnosis, non-CNS extranodal involvement was seen in 30 pts, 24 with 1 site and 6 with ≥ 2 sites; 24 had bone marrow involvement. 11 (31%) pts had blastoid variant. Median Ki-67 was 40% (range 15-100%). MIPI score was available in 17 pts [low risk (n = 5, 29%), intermediate risk (n = 9, 53%), high risk (n = 3, 18%)]. The most common frontline regimen for MCL was R-CHOP and 14 (39%) pts underwent autologous stem cell transplant in CR1. The incidence of CNS involvement was overall similar over the study period. Median time from MCL diagnosis to CNS involvement was 25 months (m) (range 0-167). 4 (11%) pts presented with CNS involvement at initial diagnosis and 32 presented at relapse (12 isolated CNS relapse and 20 concurrent CNS and systemic relapse. Abnormal CSF was noted in 27 (87%) pts [consistent with MCL diagnosis (n = 26), atypical lymphocytes (n = 1)]. Abnormal CNS imaging was reported in 27 (75%) pts [leptomeningeal (n = 18), leptomeningeal and parenchymal (n = 5), parenchymal (n = 2), ocular (n = 2)]. First line CNS-directed therapy data was available in 33 (92%) pts. 12 (34%) received intrathecal (IT) therapy alone, 19 (54%) received systemic +/- IT therapy, 2 (6%) received radiation alone, and 2 (6%) pts received no treatment (hospice). The overall CNS response to therapy was CR in 13 (42%) pts, PR in 3 (10%), SD in 8 (26%), and PD in 7 (22%) pts. Three pts received BTK inhibitors [ibrutinib (n = 2) or acalabrutinib (n = 1)] as the first CNS-directed therapy. One patient achieved a CR with a response lasting 4 m, another patient achieved a PR with response lasting 10 m. CNS response data was not available in the remaining pts. Median follow up from CNS involvement was 72 m (95% CI: 41-NR). Median EFS for the 1 st CNS-directed therapy was 3.7 m (95% CI: 1.6-6.1). At last follow up, 30 pts were deceased. The cause of death was CNS lymphoma in 10 (33%) pts and systemic lymphoma in 9 (30%) pts. Median OS from CNS involvement was 4.7 m (95% CI: 2.3-6.7). Conclusions: CNS involvement by MCL has dismal outcomes as evident by a median OS of approximately 5 m. BTK inhibitors may have a role in treatment of this rare complication, but further prospective investigation is needed.