Bennani, N. Nora

e19556 Background: CD19 chimeric antigen receptor T cell therapy possesses unique side effects including cytokine release syndrome (CRS) and immune effector cell associated neurotoxicity syndrome (ICANS). Age is a major risk factor for ICANS. However, whether ICANS in older patients is different compared to younger patients is unknown. Herein, we report clinical course, outcomes and risk factors for ICANS in older patients with large B cell lymphoma (LBCL) treated with axicabtagene ciloleucel (axi-cel). Methods: We comprehensively reviewed detailed clinical courses of ICANS in 78 adult patients with LBCL treated with axi-cel between June 2016 and October 2020. Incidence, manifestation, risk factors, treatment, and outcomes of ICANS were compared between patients age ≥60 (n=32) and <60 (n=46) years old. Results: Baseline characteristics were comparable between older and younger patients except higher proportion of high international prognostic index and underlying cerebral microvascular disease in older patients. ICANS was observed in 16 patients in the older and 24 patients in the younger age group, with a 30-day incidence of 52% and 50%, respectively. Median time to CRS and ICANS were similar between 2 age groups. The most common initial neurological findings included aphasia, dysgraphia and encephalopathy in both age groups. Table summarizes the characteristics, clinical course and interventions of ICANS in older and younger patients. In Cox regression model, the presence of CRS was the only factor associated with ICANS in both age groups. Age, history of central nervous system involvement and cerebral microvascular disease were not associated with ICANS. Importantly, all patients had complete resolution of ICANS. No elderly patients in our cohort experienced seizure as a manifestation of ICANS. Conclusions: In our study, older age was not a risk factor for ICANS. CRS was the only factor associated with ICANS in both younger and older patients. Incidence, clinical course and neurological outcomes of ICANS in older patients treated with axi-cel were comparable to younger patients. [Table: see text]

e19554 Background: Obesity is associated with a pro-inflammatory state and immune dysregulation. Retrospective studies indicate that obesity could affect toxicities and outcomes after immunotherapies including checkpoint inhibitors and allogeneic stem cell transplant. Currently, there are no data specifically on outcomes for obese patients who receive chimeric antigen receptor T (CAR-T) cells. We described the clinical outcome in obese patients with large B cell lymphoma (LBCL) who received axicabtagene ciloleucel (axi-cel). Methods: We analyzed the effect of body weight (BW) and body mass index (BMI) on toxicities and outcomes of 78 adults with LBCL who received axi-cel between June 2016 and October 2020 at Mayo Clinic. Obesity was defined as having BMI of 30 or higher. Results: Of 78 patients, 22 (28%) and 19 (24%) were classified as overweight (BMI 25-29.99 kg/m2) and obese (BMI ≥30 kg/m2), respectively. Baseline characteristics were not statistically significantly different between non-obese and obese patients. The median delivered dose of fludarabine was similar between non-obese and obese patients (89 [0-105] vs 88 [56-94] mg/m2, P=0.32) whereas the median delivered dose of cyclophosphamide was lower in non-obese patients (1503 [1077-1525] vs 1512 [1021-1660] mg/m2, P=0.01). The 30-days cumulative incidence of CRS and ICANS were similar between non-obese and obese patients. BW and BMI were not associated with CRS or ICANS. The overall response rate was 66% (CR 47%) and 68% (CR 53%) in non-obese and obese group, respectively ( P=0.83). The 1-year event free survival (EFS) and overall survival (OS) was 34.6% and 64.5%, neither were different between non-obese and obese patients (EFS 35.8% vs. 30.7%, P=0.60; OS 59.4% vs. 83.9%, P=0.18). The 1-year cumulative incidence of relapse and non-relapse mortality was comparable (60.8% vs. 69.0%, P=0.40 and 3.4% vs. 0%, P=0.42). In the Cox proportional hazards model, higher dose of fludarabine, but not cyclophosphamide, was associated with better EFS and OS; however, neither obesity nor BW were associated with toxicities and outcomes. Conclusions: In our study, Obesity was not associated with risk of toxicities or adverse survival outcomes. The effect of obesity on the pattern of LD chemotherapy dosing including toxicities and outcomes after CAR-T warrants further exploration. [Table: see text]

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.

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]

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.

7050 Background: Langerhans cell histiocytosis (LCH) is an inflammatory myeloid neoplasm manifesting as unifocal, multifocal, multisystem (MS) or pulmonary LCH (smoking-related). In pediatric LCH, somatic BRAFV600E prevalence is reported at 55-70%, and associated with increased risk of multisystem disease and early treatment failure. Our aim was to describe the prevalence of BRAFV600E mutation and evaluate its association with clinical manifestations and outcomes in adults with LCH. Methods: A retrospective review of adult patients diagnosed with LCH consecutively seen at Mayo Clinic from 2011 to 2020 was performed.Evaluation of association of BRAFV600E mutational status and clinical factors was conducted by the Chi-square test for independence. Progression-free survival (PFS) and overall survival (OS) were analyzed via the Kaplan Meier method and compared with the log-rank test to assess the effect of BRAFV600E. Results: Of the total LCH cohort ( n= 128), 88 patients with available BRAFV600E results were included in the study. Median age at diagnosis was 41y (range 19 - 88); 52.3% were male. 40 (45.5%) patients had a BRAFV600E mutation. Increasing age was associated with BRAFV600E (10-year increase OR 1.42, 95%CI 1.07-1.89; p= 0.017). No correlation was observed between BRAFV600E status and site of disease, risk organ (RO: liver, spleen, marrow) involvement, or MS disease. Patients with BRAFV600E were 4 times more likely to receive targeted therapy ( BRAF inhibitor) than non- BRAFV600E patients ( p= 0.018). After a median follow up of 46 mo (95% CI 30.8-61.2), PFS was similar between BRAFV600E and non- BRAFV600E patients ( p= 0.167). However, patients with BRAFV600E had a worse 3-year OS compared with non- BRAFV600E patients (84% vs. 97.1%, p= 0.027). Patients who died had a significantly higher age at LCH diagnosis (median 62 vs. 38 years; p= 0.0002). Conclusions: In our cohort of adults with LCH, BRAFV600E was less frequent than reported in pediatric literature and was associated with worse OS. The frequency of BRAFV600E was positively correlated with increasing age. Contrary to reports in pediatric LCH, there were no significant associations between BRAFV600E and high-risk or multisystem disease.[Table: see text]