Abstract: The therapy of hematologic malignancies has been revolutionized by the development of therapies using chimeric antigen receptor modified T-cells (CAR-T). However, CAR-T cell therapy is often associated with cytokine release syndrome (CRS), characterized by fevers, hypotension, and hypoxia, as well as immune effector cell-associated neurotoxicity syndrome (ICANS). Severe cases of CRS can result in significant morbidity and mortality. Although disease features such as tumor burden may predict for more severe CRS and ICANS, other clinical features and biomarkers predictive of CRS and ICANS remain lacking, with the exception of measurements of serum cytokines following cell infusion (PMID: 27076371, PMID: 24553386). Experimental models have implicated elaboration of inflammatory cytokines such as IL-1 and IL-6 by monocytes in the pathogenesis of CRS and ICANS (PMID: 29808007, PMID: 29808005). Accordingly, the severity and duration of CRS and ICANS can be mitigated in part by IL-6 receptor blockade with tocilizumab and treatment with corticosteroids such as dexamethasone. Recent work has implicated ascorbate in the regulation of the activity of TET enzymes in hematopoietic cells (PMID: 28825709, PMID: 28823558). Given that TET2 deficiency has been associated with increased elaboration of inflammatory cytokines such as IL-6 and IL-1 by macrophages (PMID 3026882, PMID: 28104796, PMID: 28636844), we reasoned that ascorbate deficiency might predict for more pronounced cytokine release in patients leading to more severe CRS or ICANS. We identified 13 patients receiving CAR-T cell therapy for hematologic malignancies at the University of Texas Southwestern. Plasma specimens were collected from patients at baseline prior to receipt of lymphodepleting chemotherapy and/or at two weeks following CAR-T cell infusion. Given the poor reliability of clinical ascorbate measurements due to oxidation, we used an optimized protocol incorporating a C13-labeled ascorbate internal standard to obtain highly precise serum measurements using liquid-chromatography mass spectrometry. The incidence and severity of CRS and ICANS was classified using standardized grading criteria as per the American Society for Transplantation and Cellular Therapy. We measured serum ascorbate in 7 baseline and 12 post CAR-T cell infusion specimens obtained from 13 patients, with a median age of 65 (range 53 to 77). The cohort included eight patients with diffuse large B-cell lymphoma and two patients with mantle cell lymphoma receiving CD19-targeted CAR-T cells, as well as three patients with multiple myeloma receiving BCMA-targeted CAR-T cells. Eight patients developed grade one CRS, three patients developed grade two CRS, and two patients did not develop CRS. One patient developed grade one ICANS, one developed grade two ICANS, and one developed grade three ICANS. Eight patients received dexamethasone for CRS or ICANS, and eight patients received tocilizumab. Five patients only received one dose of tocilizumab, while two received two doses and one received three doses. Taking all pre- and post-CAR-T cell infusion ascorbate measurements into account, a significant correlation was found between having low serum ascorbate levels and a higher maximal grade of CRS or ICANS (Figure 1A, r 2=-0.64, p=0.0039). Post-infusion ascorbate measurements also demonstrated a significant correlation between low serum ascorbate levels and higher maximal CRS or ICANS (Figure 1B, r 2=-0.78, p=0.0035), while there was no correlation between pre-infusion ascorbate measurements and CRS or ICANS. Finally, we noted a significant decrease in serum ascorbate levels when comparing pre-infusion to post-infusion specimens (Figure 1C, p=0.048), including five paired specimens. There was no significant correlation between serum ascorbate levels and the number of doses of tocilizumab or dexamethasone administered. Low serum ascorbate levels may be associated with an increased risk for developing severe CRS and ICANS following CAR-T cell therapy. Although follow-up studies with a larger cohort of patient are necessary to substantiate this correlation, these data provide preliminary evidence that serum ascorbate levels may serve as a useful biomarker to predict severity of CRS and ICANS. Furthermore, they suggest ascorbate supplementation as a promising future strategy to mitigate these common complications of CAR-T cell therapy. Figure 1 Figure 1. Disclosures Kansagra: Alynylam, Celgene/BMS, Cota Health, GSK, Janssen, Karyopharm, Oncopeptide, Pfizer, Takeda, Sanofi: Membership on an entity's Board of Directors or advisory committees. Anderson: Celgene, BMS, Janssen, GSK, Karyopharm, Oncopeptides, Amgen: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding. Awan: Abbvie: Consultancy; Dava Oncology: Consultancy; Johnson and Johnson: Consultancy; Incyte: Consultancy; BMS: Consultancy; Astrazeneca: Consultancy; ADCT therapeutics: Consultancy; Pharmacyclics: Consultancy; Janssen: Consultancy; Beigene: Consultancy; Merck: Consultancy; Gilead sciences: Consultancy; Cardinal Health: Consultancy; Verastem: Consultancy; MEI Pharma: Consultancy; Karyopharm: Consultancy; Celgene: Consultancy; Kite pharma: Consultancy; Genentech: Consultancy. Madanat: Stem line pharmaceutical: Honoraria; Blue Print Pharmaceutical: Honoraria; Onc Live: Honoraria; Geron Pharmaceutical: Consultancy. Patel: Agios: Membership on an entity's Board of Directors or advisory committees; PVI: Honoraria; Celgene-BMS: Membership on an entity's Board of Directors or advisory committees. Sweetenham: EMA Wellness: Membership on an entity's Board of Directors or advisory committees.

Abstract: Background: Vitamin C is an essential water-soluble vitamin required for many redox reactions in our body and its deficiency causes scurvy, a well characterized disease with multiple hematological manifestations. Studies dating back to 1950's demonstrated that patients with myeloid neoplasms tend to have lower plasma levels of vitamin C than healthy controls. Recent studies have shown that as much as 80% of patients with hematological malignancies in a cohort from Denmark had low vitamin C levels. Myeloid neoplasms tend to harbor mutations in epigenetic regulators which play a role in DNA methylation. One such mutation commonly seen in myeloid neoplasms and clonal hematopoiesis of indeterminate potential (CHIP) is TET2 for which vitamin C serves as a cofactor. There is a scarcity of clinical data on patients with low vitamin C level in myeloid neoplasms. Our study investigated the rates of vitamin C deficiency and the disease clinical and genomic characteristics associated with it at our center. Methods: We retrospectively collected data from a prospectively maintained list of patients treated for myeloid neoplasms at a large tertiary cancer center on whom vitamin C levels where serially collected during the study period. We obtained multiple baseline characteristics at the time of diagnosis including cytogenetic and molecular mutational data. Baseline characteristics were defined using descriptive statistics. Categorical variables were compared using a Fisher's exact test and continuous variables were analyzed using Mann Whitney U test for statistical significance. Institutional review board approval was obtained for the study. Statistical analysis was done using R Studio version 1.4.1717. Results: A total of 50 patients with myeloid neoplasms were identified with vitamin C levels available at least once during the study period. Nine (18%) patients had a low vitamin C level (LOW) defined as less than 0.4 mg/dl as per the Mayo lab testing with a reference range between 0.4 to 2.0 mg/dl. Baseline characteristics of patients with low vitamin C level and patients with normal vitamin C level (NORMAL) are shown in Table 1. The median vitamin C level in the LOW group was 0.2 mg/dl and NORMAL group was 1 mg/dl (p & lt;0.001). The median age at diagnosis for patients in the LOW cohort was 64 years compared to 72 years for patients with normal vitamin C level (p = 0.015). Twenty-two (53.6%) of patients were female in the NORMAL cohort while six patients (66.7%) were females in the LOW cohort (p=NS). In the vitamin C LOW group only 55% of the patients were white compared to 83% in the NORMAL group (p = 0.093). The majority of patients in the Vit C LOW group had acute myeloid leukemia (AML) 44.5%, compared to 9.8% in the group with normal vitamin C levels (p = 0.03). Median white blood cell count, platelet counts, peripheral blast count and bone marrow blast count were not statistically significant amongst the 2 groups. Majority of patients in both groups 56.1% (NORMAL) vs 77.8% (LOW) had normal cytogenetics at the time of diagnosis (p = 0.284). There was a higher tendency to harbor ASXL1 and IDH2 mutation in the cohort with LOW levels 44.5% (p = 0.09) and 22.2% (p value = 0.143) compared to 17% and 4.8% respectively in the NORMAL cohort. Conclusions: Our analysis of the baseline characteristics of patients with myeloid neoplasms with vitamin C levels reveals interesting findings including a lower age at diagnosis for patients with low vitamin C levels and higher proportion of patients with acute myeloid leukemia compared to the cohort with normal levels. We also noted a higher tendency for occurrence of certain molecular mutations including ASXL1 and IDH2 among the patients with low vitamin C level. With recent papers implicating the role of ASXL1 in leukaemogenesis these findings suggest the hypothesis that vitamin C deficiency could accelerate clonal evolution with a higher tendency to transform into acute leukemia at a lower age. Further multi-institutional studies are needed to understand the relevance of low vitamin C level in myeloid neoplasms and the role of therapeutic vitamin C supplementation to retard leukaemogenesis. Figure 1 Figure 1. Disclosures Patel: Celgene-BMS: Membership on an entity's Board of Directors or advisory committees; Agios: Membership on an entity's Board of Directors or advisory committees; PVI: Honoraria. Awan: Cardinal Health: Consultancy; Abbvie: Consultancy; Merck: Consultancy; Beigene: Consultancy; Johnson and Johnson: Consultancy; Astrazeneca: Consultancy; BMS: Consultancy; Janssen: Consultancy; Genentech: Consultancy; Dava Oncology: Consultancy; Verastem: Consultancy; ADCT therapeutics: Consultancy; Incyte: Consultancy; MEI Pharma: Consultancy; Karyopharm: Consultancy; Kite pharma: Consultancy; Celgene: Consultancy; Gilead sciences: Consultancy; Pharmacyclics: Consultancy. Anderson: Celgene, BMS, Janssen, GSK, Karyopharm, Oncopeptides, Amgen: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding. Madanat: Blue Print Pharmaceutical: Honoraria; Stem line pharmaceutical: Honoraria; Onc Live: Honoraria; Geron Pharmaceutical: Consultancy.

Abstract: Background: The risk of severe COVID-19 is increased in patients (pts) with hematologic malignancies, with a reported risk of death of 34% (Vijenthira et al, 2020). The ASH-ASTCT COVID-19 vaccine guidelines indicate that certain immunocompromised patient populations could have an attenuated response to the SARS-CoV-2 vaccine. However, most SARS-CoV-2 vaccine trials required pts to be off immune suppression to be eligible and therefore excluded most pts with hematologic malignancies. Little is known about the efficacy of SARS-CoV-2 vaccines in pts with hematologic malignancies. In this study, we aimed to evaluate the serological response of Pfizer and Moderna vaccination after two doses given in pts with hematologic malignancies with a focus on pts with myeloid malignancies. Methods: Patients with a history of hematologic malignancies treated at the University of Texas Southwestern Medical Center and received two doses of vaccination with quantitative measurement of SARS-CoV-2 IgG Spike antibody to assess vaccination response were included in this study. Baseline patient and disease characteristics including disease status and therapy given at the time of vaccination were collected. Time to vaccine response was defined as having a positive quantifiable spike IgG antibody titer per the lab reference range. The development of COVID-19 infection as well as antibody titer levels were collected. Categorical variables were compared using Chi-square and Fisher's exact tests and student t-test and ANOVA test were used to compare continuous variables. Results: A total of 61 pts with hematologic malignancies had spike IgG antibody testing after receiving 2 doses of the vaccine were included in this study. The median age at the time of vaccination was 72 (22-85) and 46% of pts were female. Eighty five percent of pts were Caucasian. The majority of pts (67.3%) had a myeloid malignancy (MDS/CMML 29.5%, AML 14.8%, myelofibrosis 16.4%, CML 6.6%), followed by chronic lymphocytic leukemia (16.4%), and others (6.6%). The median time from hematologic malignancy diagnosis to the first vaccine dose was 51 months (0.4-337 months). At the time of vaccine administration, 46 (75%) of pts were on active therapy and 39 (64%) of pts had active disease. Median time from the second vaccine dose to IgG spike antibody testing was 64 days (26-268 days). Most pts (75%) mounted a serological response with quantifiable COVID-IgG spike antibodies, 85% and 56% in myeloid and lymphoid malignancy, respectively. All pts with MDS/CMML/CCUS and CML mounted an immune response (100%), followed by acute myeloid leukemia (n: 7/9, 78%) and myelofibrosis (n: 6/10, 60%). Eight (13%) of pts were receiving hypomethylating agent therapy at the time of vaccination and all (100%) had a positive IgG response. Only one patient developed COVID-19 infection post vaccination with a documented IgG response and 2 pts had COVID-19 infection prior to the first dose of vaccination, both of these pts had IgG titers & gt;10,000. Sixty percent of pts (9/15) with negative IgG response received treatment with either CD20 monoclonal antibodies or BTK inhibitors within 12 months of the first vaccine dose. Two out of three pts (67%) receiving Ruxolitinib had negative serology. Seven pts were on treatment with hydroxyurea, interestingly, all but the 2 pts with polycythemia vera had a negative antibody titer while on treatment with hydroxyurea. There was a strong positive correlation between vaccine titer and absolute lymphocyte count (r 2=0.27, p & lt;0.001) (Figure). Conclusions: In this retrospective study, we demonstrate a higher rate of COVID-19 vaccine efficacy in pts with myeloid malignancy with varying responses per treatment and disease subtype compared to pts with B-cell malignancy with variable anti-CD20 or BTK inhibitor therapy. Pts with myelodysplastic syndromes, overlap syndromes of clonal cytopenia of undetermined significance all developed spike antibodies irrespective of hypomethylating therapy or Hydrea as did pts with chronic myeloid leukemia. However, pts with polycythemia vera and those on treatment with Ruxolitinib had an attenuated response to the vaccine. Albeit this single center study, pts with myelodysplastic syndromes should be offered COVID vaccines irrespective of their blood counts or ongoing treatment. Our findings should be validated in a larger group of patients. Figure 1 Figure 1. Disclosures Patel: Agios: Membership on an entity's Board of Directors or advisory committees; Celgene-BMS: Membership on an entity's Board of Directors or advisory committees; PVI: Honoraria. Anderson: Celgene, BMS, Janssen, GSK, Karyopharm, Oncopeptides, Amgen: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding. Awan: Cardinal Health: Consultancy; BMS: Consultancy; Dava Oncology: Consultancy; Karyopharm: Consultancy; Merck: Consultancy; Johnson and Johnson: Consultancy; Incyte: Consultancy; Beigene: Consultancy; Verastem: Consultancy; MEI Pharma: Consultancy; Celgene: Consultancy; Kite pharma: Consultancy; Gilead sciences: Consultancy; Pharmacyclics: Consultancy; Janssen: Consultancy; Abbvie: Consultancy; ADCT therapeutics: Consultancy; Astrazeneca: Consultancy; Genentech: Consultancy. Madanat: Blue Print Pharmaceutical: Honoraria; Onc Live: Honoraria; Stem line pharmaceutical: Honoraria; Geron Pharmaceutical: Consultancy.

Abstract: Introduction: CAR T-cells remain in a quiescent or dormant state when unstimulated, showing no proliferative activity. In contrast, upon specific antigen stimulation (i.e., CD19) CAR T-cells divide both in-vitro and in-vivo, initiate immune responses and can kill their target cells in the body. However, one of the major physiological immune changes with increased age is the progressive impairment of T-cell responses. This process termed immunosenescence (which may be similar T-cell exhaustion) is associated with the shortening of telomeres, specific DNA repeated sequences that protect the end of linear chromosomes from degradation and fusion with neighbor chromosomes. We aim to investigate change in T-cell telomere length with CAR-T cell therapy and its potential impact on outcome in patients receiving CART immunotherapy. Methods: We enrolled adult patients (age range: 30-80 years old) receiving CART immunotherapy for diffuse large B cell lymphoma (DLBCL), multiple myeloma (MM), mantle cell lymphoma (MCL), or follicular lymphoma (FL). We collected peripheral blood at two time points: i) pre-lymphodepletion therapy and ii) two weeks post CAR-T cell infusion. Peripheral blood mononuclear cells were isolated from blood via density gradient and T-cells isolated from PBMC with magnetic beads (negative selection). Telomere lengths are quantified from T-cells by using a highly sensitive technique called TeSLA (Telomere Shortest Length Assay) that allows absolute quantification of both the average telomere length and the lengths of critically short telomeres, which are believed to play a major role in promoting cell cycle arrest and T-cell exhaustion. Results: We identified 7 patients receiving CAR T cell therapy for hematological malignancies at University of Texas Southwestern Medical Center. The cohort included 7 patients, 2 patients with DLBCL and 1 patient with MCL receiving CD19 CAR-T Cell therapy and 4 patients with MM receiving BCMA CAR-T cell therapy. Median age of patient was 65 yrs. Median follow up was 273 days post CAR T-cell therapy with all patients being alive at last follow-up. Two patients experienced Grade I Cytokine release syndrome (CRS), two patients with Grade 2 CRS and one patient with Grade 2 ICANS. Our initial analysis shows that patients telomere lengths changes pre and post CAR T-cell infusion. Regarding change in critically short telomere ( & lt;1.6kb); 6 out of 7 patients had reduction the shorter telomere from BL to post CAR-T. We are currently evaluating the effect of change in telomere length on outcomes. Conclusions: CAR T-cell therapy is a game-changer for hematological malignancies; however, disease still relapse. Understanding the mechanics of poor response or relapse after CAR T-cell therapy is critical in advancing the field. Initial results suggest T-cell telomere length are significantly affected during CAR T-cell manufacturing process and post infusion. These results are potentially important as telomere length can be utilized as a biomarker to predict CAR T-cell therapy outcomes. Figure 1 Figure 1. Disclosures Anderson: Celgene, BMS, Janssen, GSK, Karyopharm, Oncopeptides, Amgen: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding. Awan: Verastem: Consultancy; Incyte: Consultancy; Cardinal Health: Consultancy; Dava Oncology: Consultancy; BMS: Consultancy; ADCT therapeutics: Consultancy; Beigene: Consultancy; Celgene: Consultancy; Karyopharm: Consultancy; Pharmacyclics: Consultancy; MEI Pharma: Consultancy; Merck: Consultancy; Kite pharma: Consultancy; Gilead sciences: Consultancy; Johnson and Johnson: Consultancy; Abbvie: Consultancy; Janssen: Consultancy; Astrazeneca: Consultancy; Genentech: Consultancy. Madanat: Onc Live: Honoraria; Blue Print Pharmaceutical: Honoraria; Geron Pharmaceutical: Consultancy; Stem line pharmaceutical: Honoraria. Patel: Celgene-BMS: Membership on an entity's Board of Directors or advisory committees; PVI: Honoraria; Agios: Membership on an entity's Board of Directors or advisory committees. Sweetenham: EMA Wellness: Membership on an entity's Board of Directors or advisory committees. Kansagra: Alynylam, Celgene/BMS, Cota Health, GSK, Janssen, Karyopharm, Oncopeptide, Pfizer, Takeda, Sanofi: Membership on an entity's Board of Directors or advisory committees.