Development Of Cytokine Release Syndrome Research Articles

The adrenal stress response is an essential host response against therapy-induced lethal immune activation.

Cytokine release syndrome (CRS) is a systemic inflammatory syndrome associated with infection- or drug-induced T cell activation and can cause multiple organ failure and even death. Because current treatments are ineffective in some patients with severe CRS, we set out to identify risk factors and mechanisms behind severe CRS that might lead to preventive therapies and better clinical outcomes in patients. In mice, we found that deficiency in the adrenal stress response-with similarities to such in patients called relative adrenal insufficiency (RAI)-conferred a high risk for lethal CRS. Mice treated with CD3 antibodies were protected against lethal CRS by the production of glucocorticoids (GC) induced by the adrenal stress response in a manner dependent on the scavenger receptor B1 (SR-BI), a receptor for high-density lipoprotein (HDL). Mice with whole-body or adrenal gland-specific SR-BI deficiency exhibited impaired GC production, more severe CRS, and increased mortality in response to CD3 antibodies. Pretreatment with a low dose of GC effectively suppressed the development of CRS and rescued survival in SR-BI-deficient mice without compromising T cell function through apoptosis. Our findings suggest that RAI may be a risk factor for therapy-induced CRS and that pretreating RAI patients with GC may prevent lethal CRS.

Arginine-Glycine-Aspartic Acid-anchored Curcumin-based Nanotherapeutics Inhibit Pyroptosis-induced Cytokine Release Syndrome for In Vivo and In Vitro Sepsis Applications.

We aimed to design RGD-anchored liposomes encapsulating an antipyroptosis drug that could efficiently target macrophages and relieve the rate of cytokine release syndrome, providing a new strategy for sepsis treatment, especially sepsis-induced acute renal injury. Sepsis is a clinical syndrome of life-threatening organ dysfunction caused by host response disorders due to infection. Sepsis has a high incidence and remains one of the leading causes of death worldwide. Macrophage-mediated pyroptosis plays an important role in the occurrence and development of cytokine release syndrome and organ injury caused by sepsis. Curcumin can inhibit inflammasome assembly and slow the progression of pyroptosis by scavenging intracellular reactive oxygen species, but it has poor water solubility and low bioavailability. The emergence of drug-delivery nanosystems has overcome this problem, but there is still a lack of research on how to accurately deliver antipyroptotic drugs to innate immune cells and subsequently hinder pyroptosis. We constructed a curcumin-loaded RGD-modified liposome (RGD-lipo/Cur) and demonstrated that RGD-lipo/Cur could effectively target macrophages. In vitro, RGD-lipo/Cur reduced the upregulation of caspase-1, caspase-3, NLRP3, IL-1β and GSDMD, inhibiting pyroptosis, reducing oxidative stress, and attenuating the proinflammatory cytokine cascade. RGD-lipo/Cur was considered to have great potential for sepsis treatment.

258 - Utilizing Biomarkers, CRP and Ferritin, to Predict the Development of Cytokine Release Syndrome in Patients Receiving Chimeric Antigen Receptor Cell Therapy

258 - Utilizing Biomarkers, CRP and Ferritin, to Predict the Development of Cytokine Release Syndrome in Patients Receiving Chimeric Antigen Receptor Cell Therapy

Early prediction of cytokine release syndrome by measuring phosphate and magnesium levels following chimeric antigen receptor T cell therapy.

Cytokine release syndrome (CRS) is a life-threatening side effect of chimeric antigen receptor T (CAR-T) cell therapy. This study investigated whether serum inorganic phosphate (IP) and magnesium (Mg) levels are predictive markers of CRS development. This single-center retrospective cohort study enrolled 16 consecutive patients with diffuse large B-cell lymphoma who had received CAR-T cell therapy. Logistic regression models with generalized estimating equations were used to evaluate whether changes in IP and Mg levels from their baseline values were associated with the development of CRS within 48 hours. Decreased IP and Mg levels from baseline (per 10% change) were associated with an increased CRS incidence (adjusted odds ratio 2.18 [95% confidence interval (CI), 1.31-3.62], 3.18 [95% CI, 1.57-6.44], respectively). Changes in IP and Mg concentrations within 48 hours may be useful predictive markers of CRS onset.

CD4 CAR-T cells targeting CD19 play a key role in exacerbating cytokine release syndrome, while maintaining long-term responses

BackgroundTo date, T cells redirected with CD19-specific chimeric antigen receptors (CAR) have gained impressive success in B-cell malignancies. However, treatment failures are common and the occurrence of severe toxicities, such...

Cytokine Release Syndrome (CRS) Is Not Required for CAR-T Cell Efficacy in Aggressive Large B-NHL

BACKGROUND Chimeric antigen receptor (CAR) T-cell therapy for treatment of aggressive large B-cell non-Hodgkin lymphoma (B-NHL) has changed management and outcomes for this disease. Treatment with CAR T-cells is accompanied by a unique set of adverse effects, including development of cytokine release syndrome (CRS). Though rates of CRS varied in trials, the development of severe (Grade 3 or 4) CRS was rare and similar incidences have been noted in real world studies. Here, we addressed whether the development of CRS is associated with outcomes in patients with aggressive large B-NHL undergoing treatment with CAR T cells. METHODS Patients aged ≥18 years with aggressive large B-NHL who underwent apheresis between May 2018 and January 2021 for commercial CAR T-cell therapy at eight academic US medical centers were identified from the Cell Therapy Consortium (CTC) registry. Providers could prescribe either axicabtagene ciloleucel (axi-cel) or tisagenlecleucel (tisa-cel). CRS was graded using ASTCT consensus criteria. Tumor response 90 days after CAR T-cell infusion was assessed per Lugano criteria by the treating clinician. Persistent cytopenias were defined as ANC<1000 and/or Plt<50 and evaluated at the following intervals post infusion: day 30, 3 months, 6 months, 9 months, and one year. Cox regression analysis and the Kaplan Meier method were used for survival outcomes. Logistic regression analysis was used to assess association with tumor response and persistent cytopenias. RESULTS This study included 351 patients who underwent apheresis for commercial CAR T cell therapy for aggressive large B-NHL (Table 1A). Of these, 262 (74.4%) developed CRS while 90 (25.5%) did not. The median age at apheresis was 61 (range 18-88) among patients who developed CRS and 65 (range 37-85) among those who did not (p=0.005). Of the patients included, 202 (57.6%) received axi-cel and 149 (42.5%) received tisa-cel. With median follow up of 21.6 months, there were no differences in progression free survival (PFS) or overall survival (OS) between patients who developed CRS and those who did not. Median PFS in patients who did not develop CRS was 5.99 months compared to 5.89 months (p=0.99) in those who did. Median OS in patients who did not develop CRS was 26.6 months compared to 17.5 months in patients who did (p=0.16). Exploratory analysis showed that CRS grade did not influence PFS or OS (Figure 1). Results of the multivariate analysis are summarized in Table 1. The development of CRS did not have a significant impact on PFS or OS. A peak ferritin level of greater than 5000 within 28-days following CAR T-cell infusion was associated with worse PFS (HR 2.61; CI: 1.71-3.98, p<0.001) and OS (HR 2.38; CI: 1.50-3.76, p<0.001). LDH greater than the upper limit of normal was associated with worse progression-free (HR 2.11; CI: 1.49-2.98, p<0.001) and OS (HR 2.34; CI: 1.55-3.53, p<0.001). The administration of steroids for treatment of CAR T-cell associated toxicities had no significant impact on PFS or OS. Presence of bulky disease (≥10 cm) had no impact on PFS but was associated with worse OS (HR 1.81; CI: 1.29-2.75, p=0.005). Receipt of bridging therapy was associated with worse PFS (HR 1.58; CI: 1.11-2.24, p=0.011), though not OS. At 30 days post-infusion, there was no difference in ORR (66% vs 52%, p=0.081) or CR rate (39% vs 27%, p=0.155) between patients who developed CRS and those who did not. The occurrence of CRS within 28 days of treatment was significantly associated with cytopenias at day 30 (p=0.001), but not at any other time point. Amongst patients with Grade ≥3, 63% had cytopenias at day 30, compared to 47% among patients who did not have CRS (p=0.142). Grade ≥3 CRS was not significantly associated with cytopenias beyond day 30. CONCLUSION Survival outcomes were similar in patients with aggressive large B-NHL treated with CAR T-cell therapy who did or did not develop CRS. Furthermore, the occurrence of CRS had no impact on ORRs or CR rates. Having CRS was associated with cytopenias at day 30 post infusion, though not at subsequent time points. These findings lend further support to the finding that development of CRS does not impact efficacy of CAR T-cell therapy. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

Effects of HLA Mismatches on Cytokine Release Syndrome and Associated Non-Relapse Mortality in Allogeneic Stem Cell Transplantation with Post-Transplant Cyclophosphamide

Background Post-transplant cyclophosphamide (PTCy) is an effective method for graft versus host disease prevention in allogeneic stem cell transplantation (alloSCT). The alloreactive T-cell response in the first days after PTCy-alloSCT can induce a systemic inflammatory response known as cytokine release syndrome (CRS). The incidence of CRS appears to increase with higher degrees of HLA mismatch between patient and donor. In haplo-identical PTCy-alloSCT, CRS occurs frequently (73-94%) and has a negative impact on non-relapse mortality (NRM) and survival. In 10/10 HLA matched related and unrelated allogeneic stem cell transplantation (MRD/MUD PTCy-alloSCT), CRS is less frequently observed (14-23%) without effects on NRM and survival. The specific contributions of different HLA mismatches in CRS development are not well known. Aim To study the effects of HLA mismatching in MRD/MUD PTCy-alloSCT transplantation on development of CRS and CRS-associated NRM and survival. Methods We retrospectively studied CRS, survival and NRM in a group of 97 MRD/MUD PTCy-alloSCT patients with different degrees of HLA matching (20% of patients were 12/12, 50% 10/10 and 30% 9/10 HLA-matched). Results CRS developed in 69% of patients, mostly grade 1 (85%), 12% grade 2 and 3% grade 3. CRS developed significantly more in patients transplanted with a 9/10 or 10/10 match compared to a 12/12 match (90% and 75% versus 26%). By focusing on the maximum grade of fever developing during CRS, CRS severity grading was refined, revealing effects of specific HLA mismatches on CRS. In 10/10 matched patients, HLA-DPB1 non-permissiveness significantly increased grade 2-3 fever CRS incidence from 10 to 62%. Although regarded to be unimportant in HLA matching, single HLA-DRB3/4/5 mismatches could induce grade 3 fever CRS. Strongest effects on fever developed in 9/10 matched patients (35% grade 3 fever CRS), showing differences between various HLA mismatch groups. HLA-DRB1 mismatches induced significantly higher fever than HLA-C mismatches. The total number of HLA mismatches (combined HLA-A, B, C, DRB1, DRB3/4/5, DQ and DP non-permissive mismatches) was found to correlate with the height of fever developing. Importantly, patients with grade 3 fever CRS showed significantly increased NRM and significantly inferior survival compared to patients with grade 0-2 fever CRS. Conclusions In contrast to earlier publications in which CRS was demonstrated mainly in haplo-identical PTCy-alloSCT, we show that also in HLA matched related and unrelated PTCy-alloSCT incidence of CRS can be high and influence transplantation results. Development of CRS is dependent on the degree of HLA matching (90% in 9/10, 75% in 10/10 and 26% in 12/12 matched patients). By focusing on the maximum grade of fever developing during CRS, CRS severity grading can be refined, revealing effects of specific HLA mismatches on CRS. The height of fever during CRS is dependent on the number and types of HLA mismatches. CRS with grade 3 fever increases NRM and decreases survival. HLA matching decisions may be used to prevent grade 3 fever CRS, and thereby possibly also NRM. Alternatively, anti-inflammatory interventions may be considered in patients developing grade 3 fever early after alloSCT.

Sarcopenia Prevalence and Influence on the Development of Toxicity and Length of Stay in Patients with Relapsed and Refractory Myeloma Treated with Commercial Anti-BCMA CART Cells

Background Sarcopenic muscle loss has well-documented adverse impacts on treatment outcomes and mortality across cancer types and is particularly prevalent in patients with multiple myeloma, reported in 54% of newly diagnosed patients (Nandakumar ASCO 2022). Two chimeric antigen receptor T-cell (CAR-T) constructs have been FDA approved for relapsed/refractory multiple myeloma (RRMM) after exposure to at least 4 prior lines of therapy. MM Treatment combinations frequently incorporate high dose dexamethasone, well known to cause muscle atrophy, and patients may be on therapy for many years prior to becoming eligible for commercial products with associated detrimental effects from cumulative toxicities. We sought to determine the prevalence of sarcopenia in a real-world cohort of patients with RRMM presenting for commercial CAR-T. Methods We identified all patients presenting to our center treated with commercially approved CAR-T with available restaging imaging performed prior to lymphodepleting chemotherapy (LD-chemo). Cross-sectional area (CSA) of skeletal muscle were measured using Sliceomatic software (v6, Tomovision, 2022), abdominal images obtained from low-dose CT of PET/CT scans, standardized to the midpoint of of the L3 vertebrae. CSA was standardized to the square of patient height to compute skeletal muscle index (SMI, cm2/m2). Patients were categorized as sarcopenic according to international gender-specific consensus cutoffs for SMI, male: < 55.4 cm2/m2 and female: < 38.9 cm2/m2 (Mourtzakis et al, 2008) Patients with the following FISH cytogenetics were considered high risk: t(4;14), t(14;16) and deletion 17p/monosomy 17 whereas the remainder were standard risk. All variables were summarized with descriptive statistics, Mann-Whitney U test, students t-test, chi-squared or Fisher's exact were used where appropriate. Analyses were conducted in Stata (16.1, StataCorp LLC, College Station, TX). Results The cohort consisted of 61 patients, 55 (90%) received ide-cel and 6 (10%) received cilta-cel. Baseline characteristics are summarized in Table 1. Of these 16 (26%) were ≥70 years at the time of treatment and 36 (59%) had co-morbidity index >2 at the time of therapy (Sorror, Blood 2005). All scans were performed a median of 16 days prior to CAR-T administration (range 2-90). Prior to CAR-T administration 47 (77%) of patients met criteria for sarcopenia based on their pre-LD chemo restaging imaging. Male patients were more likely than women to meet criteria for sarcopenia (89% vs 62%, p=0.01) and 31 (50%) met criteria for sarcopenic overweight or obesity. Sarcopenic patients had poorer baseline performance status ECOG >=2 (23% vs 7%, p=0.17), higher baseline ferritin (p=0.08) and higher baseline tumor burden as defined by >50% marrow involvement (40% vs 14%, p=0.08) when compared to non-sarcopenic patients, although not significant at the P=0.05 level. The majority (63%) of sarcopenic patients did not meet criteria for registration trials. No significant relationship was found between the presence of sarcopenia and the development of cytokine release syndrome, but all patients who developed neurotoxicity (any grade) had underlying sarcopenia (any grade ICANS 12/47, 26% vs 0%, p=0.04). A greater proportion of sarcopenic patients had extended lengths of stay >=9 days 51% vs 21%, p=0.05). In total 24/61 (39%) were recommended for post-discharge rehab/physical therapy, of whom the majority (N=20) had baseline sarcopenia. Similarly, 13/61 (21%) required additional supports at home on discharge, N=10 with baseline sarcopenia. Conclusion Sarcopenia is highly prevalent, found in 77% of patients attending for BCMA-directed CAR-T therapy in the commercial setting. We have shown that analysis of body habitus is straightforward to perform using images acquired as standard and could inform practice. In the real-world setting, sarcopenic patients appear to be at higher risk of developing neurotoxicity, although this merits further investigation. Although high prevalence of sarcopenia in this sample may preclude statistical detection of its adverse clinical impacts, it is clearly a significant clinical issue for patients undergoing complex immunotherapies for MM and warrants further research and intervention. Pre-habilitation strategies may be beneficial while patients are awaiting apheresis availability, or during cell manufacturing. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

Effective Cell Dose and Functional Attributes of Azercabtagene Zapreleucel (azer-cel; PBCAR0191) Associate with Allogeneic CAR T-Cell Safety and Efficacy in Patients with Relapsed/Refractory B-Cell Lymphoma

Background: Characterization of product cellular attributes contributing to the in vivo expansion and toxicity of allogeneic, CD19-directed chimeric antigen receptor (CAR) T-cell therapy is necessary to optimize efficacy and safety. Using a single step process, the azer-cel CD19 CAR is knocked into the T-cell receptor alpha constant (TRAC) gene locus via a TRAC-specific ARCUS nuclease in activated T cells. Unlike autologous CAR T-cell therapy, all allogeneic CAR T products are cryopreserved. In this phase I study of the allogeneic, CD19-directed CAR T azer-cel, we analyzed post-thaw product attributes and cell composition of the infused product associated with pharmacokinetics (PK), pharmacodynamics (PD), and clinical outcomes (NCT03666000). Methods: Azer-cel was administered as a single infusion to 44 subjects across several dose levels and fludarabine/cyclophosphamide lymphodepletion regimens. CAR T cell peak expansion (Cmax), PK and area under the concentration-time curve (AUC) was assessed by flow cytometry and PD by multiplex cytokine assays. Azer-cel post-thaw cell composition was assessed by flow cytometry (minimally differentiated stem central memory [SCM], CC-chemokine receptor 7 (CCR7)+; differentiated effector memory, CCR7-). Effective cell number infused for any antigenically defined population was estimated using the product of the population percentage and the total post-thaw viable cell number. Overall tumor burden was measured as sum of the products of perpendicular diameters of target lesions and response was evaluated using Lugano 2016 criteria. Responders had either a complete or partial response at Day 28 or later. Relationships to safety events and efficacy were assessed using univariate correlative analyses (variables selected based on Pearson correlation coefficients ρ(rho)>0.35 unless specified, P-value <0.05). Results: Peak azer-cel levels and AUC varied by dose level with median Cmax ranging from 38 cells/mL at DL2 to 6.7x 104 cells/mL at DL4b, whereas median AUC0-28 ranged between 3 x 102 to 5.1x 105(cells/mL*days). Both azer-cel Cmax and AUC correlated strongly with SCM cell dose (P=0.009 & P=0.0026, respectively). Development of cytokine release syndrome (CRS) associated with effective SCM CD8+ cell dose (P<0.05) and total tumor burden (P=0.0087), in addition to Cmax of the cytokines interleukin (IL)-6, TNFα, MIP1α, IL-10 and C-X-C motif chemokine ligand 10 (CXCL10) or Interferon gamma-induced protein 10 (IP10) (P<0.01). Immune effector cell-associated neurotoxicity syndrome (ICANS) correlated with azer-cel Cmax (P=0.035), AUC (P=0.0057), total tumor burden (P=0.004), and effective SCM CAR T cell dose (P<0.05), as well as changes in a distinct set of cytokines that included IL-2, IL-8, IIL-15, IL-6, and IP10 (P<0.05). Grade >3 ICANS correlated strongly with effective SCM CD4+ cell dose (P=0.0015), differentiated CD4+CCR7- cell dose (ρ =0.34, P=0.029) and CD4:CD8 ratio (ρ = 0.32, P= 0.036), in addition to Cmax of IL-6, IL-2 and IP10 (P< 0.01). Overall response to azer-cel treatment negatively correlated with differentiated CD4+ CCR7- cell dose (P=0.04). Conclusions: Post-thaw product composition and effective cell dose are predictive for in vivo expansion potential, CAR-T-related adverse events and response to treatment with azer-cel. This is the first analysis of an allogeneic CD19 CAR T product composition to demonstrate that strategies intended to maximize stem central memory T-cell fraction (CCR7+) while limiting CD4+ CCR7- differentiated fraction may improve safety and efficacy of CAR T therapy.

Pretreatment with Tocilizumab Prior to the CD3 Bispecific Cevostamab in Patients with Relapsed/Refractory Multiple Myeloma (RRMM) Showed a Marked Reduction in Cytokine Release Syndrome Incidence and Severity

Background: Blockade of the cytokine IL-6 receptor by monoclonal antibodies, such as tocilizumab (TCZ), is a key strategy for the management of both CAR-T and T-cell dependent bispecific monoclonal antibody (TDB) induced cytokine release syndrome (CRS). Preclinical data indicate that inhibition of IL-6, IL-1, or TNF-α signaling prior to TDB administration can prevent development of CRS without any impact on anti-tumor activity (Li et al. Sci Transl Med 2019). To test this hypothesis in the clinic, a dedicated TCZ pretreatment arm was added to the ongoing GO39775 Phase I study (NCT03275103) of cevostamab, an FcRH5xCD3 TDB, to determine whether a single dose of TCZ administered prior to the first dose of cevostamab can reduce the incidence of CRS. Methods: Patients (pts) who have RRMM for which no established therapy is available, appropriate or tolerable were enrolled in a dedicated TCZ pretreatment arm. Cevostamab was administered intravenously (IV) in a 21-day Cycle (C). A single 3.6mg priming dose was given on Day (D) 1 of C1 followed by a target dose of 90mg on C1D8 and then C2D1 and beyond. A single IV 8mg/kg dose of TCZ was administered as a pretreatment on C1D1 two hours prior to the administration of cevostamab. Patient data from the previously enrolled non-TCZ 3.6/90mg dosing arm served as a retrospective comparator. Pts in both arms received corticosteroid, antihistamine and acetaminophen premedication prior to cevostamab. CRS is reported using ASTCT criteria (Lee et al. Biol Blood Marrow Transplant 2019). Results: At data cut-off (March 8, 2022), 28 pts had enrolled in the TCZ pretreatment arm (median age: 64.5 years) and 44 pts in the non-TCZ comparator (median age: 63.0 years). Median prior lines of therapy were 4 (2.0-7.0) and 6 (2.0-11.0) in the TCZ pretreatment and non-TCZ arms, respectively. Twenty-two pts (78.6%) were triple-class refractory and 12 pts (42.9%) were penta-refractory in the TCZ pretreatment arm, vs. 38 (86.4%) triple-class refractory and 32 (72.7%) penta-refractory pts in the non-TCZ arm. Pts in the TCZ arm had a median time on study of 4.7 months (range: 0.3-11.3) vs. 13.1 months (range: 0.2-30.8) in the non-TCZ arm. All patients in the TCZ arm experienced at least one adverse event (AE). Overall, 35.7% of pts in the TCZ arm experienced CRS as compared to 90.9% in the non-TCZ 3.6/90mg group (see figure). One patient in each group experienced G3 CRS and no G4/G5 events were observed. Fewer pts required TCZ to treat CRS (5/28) in the TCZ arm than the non-TCZ arm (16/44). Only two pts on the TCZ arm had more than one CRS event (vs. 12/44 non-TCZ) and no CRS events were observed at C2 and beyond (vs. 5/44 non-TCZ). Rates of non-CRS AEs (notably thrombocytopenia, infections, and liver enzyme elevations) in the TCZ arm were similar to the non-TCZ arm with the exception of neutropenia (Trudel et al. ASH 2021). In the TCZ arm 64.3% of pts experienced G3/G4 neutropenia as compared to 38.6% in the comparator arm. In both arms, neutropenia events were reversible, manageable with growth factor as indicated, and none led to the discontinuation of cevostamab. Consistent with preclinical data, no apparent negative impact on anti-tumor activity was observed. The overall response rate in the TCZ arm with 90mg target dose was 50% (13/26) [95% CI: 28.9-71.2] compared to 37.2% (16/43) [95% CI: 21.6-52.8] in pts receiving 90mg without TCZ pretreatment. Very good partial response or better (VGPR+) rates were 26.9% vs. 25.6%, respectively. Available pharmacodynamic data did not demonstrate any apparent change in measures of T-cell activation and proliferation in pts receiving TCZ pretreatment. Consistent with the known mechanism of action of TCZ, levels of C-reactive protein, a downstream product of hepatic IL-6 activation, were heavily suppressed in the vast majority of pts in TCZ arm suggestive of near-complete inhibition of the IL-6 signaling pathway. Conclusions: Clinical data from the GO39775 study shows for the first time that TCZ pretreatment can significantly reduce the risk of developing TDB-induced CRS without an apparent impact on anti-myeloma activity. The data support additional investigation of the use of anti-cytokine pretreatment with the goal of substantially reducing the frequency and potentially the severity of CRS. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

Severity of Cytokine Release Syndrome Influences Outcome After Axicabtagene Ciloleucel for Large B cell Lymphoma: Results from the US Lymphoma CAR-T Consortium.

The majority of patients with large B-cell lymphoma treated with axicabtagene ciloleucel (axi-cel), an anti-CD19 chimeric antigen receptor (CAR) T-cell therapy, develop cytokine release syndrome (CRS). Whether the lack of development of CRS with axi-cel is associated with inferior lymphoma outcomes is unknown. Additionally, relationship between CRS grade and lymphoma outcome is not well established. The US Lymphoma CAR T Consortium includes seventeen US academic centers that contribute data independently of manufacturers. We analyzed the modified intent-to-treat population of 275 patients receiving axi-cel in two different ways: 1) Two group analysis comparing no CRS with any grade CRS; 2) Three group analysis comparing grade 0 CRS with grade 1 to 2 CRS, and grade 3-5 CRS. In this large multi-center observational cohort of 275 patients receiving axi-cel, 9% (n = 24) did not develop CRS, 84% (n = 232) developed grade 1-2 CRS, and 7% (n = 19) developed grade 3 to 5 CRS. Patients without CRS, compared with those having any grade CRS, had similar overall response rates (ORR), lower complete response (CR) rates and inferior progression free survival (PFS) with no statistically significant difference in overall survival (OS). Patients experiencing grade 1 to 2 CRS had superior CR rate and PFS, as compared to those without CRS or with grade 3 to 5 CRS. Grade 3 to 5 CRS was associated with a worse OS. Overall, durable responses were seen in patients that did not develop CRS, however grade 1 to 2 CRS was associated with better outcomes while those with grade 3 to 5 experienced the worse outcomes.

CD123-directed allogeneic chimeric-antigen receptor T-cell therapy (CAR-T) in blastic plasmacytoid dendritic cell neoplasm (BPDCN): Clinicopathological insights

PurposeBlastic plasmacytoid dendritic cell neoplasm (BPDCN) is a hematologic malignancy associated with overexpression of CD123. Allogeneic chimeric antigen receptor T cells (CAR-T) directed against CD123 in BPDCN have been studied in clinical trials. We performed post-mortem analysis of a patient treated with anti-CD123 CAR-T to elucidate cause of death, development of cytokine release syndrome (CRS), and tissue distribution of UCART123 cells. MethodsA post-mortem multidisciplinary clinicopathologic analysis was performed with digital droplet polymerase chain reaction of isolated blood and tissue ribonucleic acid (RNA) to evaluate tissue distribution of infused CAR-T. Multiparameter flow cytometry for detection of CAR-T was used for whole blood samples. Cytokine levels in plasma were measured using multiplex bead assay. Gene expression profiling on isolated RNA was performed using semi-custom Nanostring immune gene panel and RNA-sequence method. RNA in situ hybridization was performed using CAR-specific probe. ResultsThe patient developed severe clinical CRS refractory to corticosteroids, tocilizumab, and lymphodepletion. Despite significant reduction in BPDCN lesions, the patient passed away on day 9 of CAR-T. Autopsy results show that following lymphodepletion and UCART123 administration, the patient remained severely lymphopenic with few UCART123 cells detected, predominantly localized to spleen. ConclusionsNo definitive cause of death was determined, but we hypothesized that the patient may have succumbed to CAR-T-mediated cardiopulmonary toxicity. UCART123 cells displayed low overall distribution, with predominance in immune organs and tissues. Mechanism of CRS development is still poorly understood in patients receiving CAR-T therapy. Future directions in the field developing CD123-targeted agents in BPDCN are discussed.

P1369: PRETRANSPLANT MODIFIED ENDOTHELIAL ACTIVATION AND STRESS INDEX (M-EASIX-7): A PREDICTOR OF PROGNOSIS IN ALLOGENEIC HEMATOPOIETIC STEM CELL TRANSPLANTATION

Background: Endothelial damage is considered to be the major underlying mechanism in the physiopathogenesis of transplant related complications including graft versus host disease (GVHD), thrombotic microangiopathy (TMA), sinusoidal obstruction syndrome (SOS) and sepsis. A novel scoring index, Endothelial Activation and Stress Index (EASIX), is a simple method consisting of endothelial activation parameters, which was indicated to predict GVHD and posttransplant survival. Similarly, modified EASIX (mEASIX) is a marker of endothelial dysfunction and has been shown to be associated with the development of cytokine release syndrome after CAR-T cell therapy. Aims: In this study, we investigated the role of EASIX and mEASIX scores in the prediction of transplant related complications and survival in patients undergoing allogeneic hematopoietic stem cell transplantation (alloHCT). Methods: A total of 398 alloHCT recipients [median age: 43(17-71) years; male/female: 243/155] were included in this retrospective study. EASIX [lactate dehydrogenase (U/L) x creatinine (mg/dl) / platelets (109/L)] and mEASIX [lactate dehydrogenase (U/L) x C reactive protein (CRP) (mg/dl) / platelets (109/L)] scores were calculated on days -7, 0, +3 and +7. Statistical analysis was performed based on log2 transformed values. Patient and transplant characteristics are summarized in Table 1. Results: Median follow-up time was 573.5 (4-3877) days. Probability of OS was estimated to be 35.1% (1343 ± 351.7; 95% CI: 653.6-2032.3), while the probabilities of day-30 mortality, day-100 mortality and NRM were 6%, 12.5% and 49% respectively. In multivariate analysis EBMT score (p=0.026, HR: 1.177; 95% CI: 1.019-1.359), CRP (p=0.033, HR: 1.004; 95% CI: 1.000-1.008), EASIX-7 (p=0.042, HR: 0.182; 95% CI: 0.035-0.941) and mEASIX-7 (p=0.016, HR: 2.668; 95% CI: 1.202-5.924) were found to have significant impact on OS. The predictive effect of mEASIX-7 was confirmed for day-30 mortality (p=0.038; HR: 1.7; 95% CI: 1.030-2.805). A positive correlation was demonstrated between mEASIX-7 and SOS (p=0.013; r=0.249). On the other hand, mEASIX+7 was found to have a significant impact on the development of engraftment syndrome (p=0.028; HR: 1.403; 95% CI: 1.038-1.896), EASIX+3 on TMA (p=0.027; HR: 2.361; 95% CI: 1.100-5.066) and mEASIX0 on TMA (p=0.011; HR: 2.209; 95% CI: 1.199-4.068). Based on the optimal cutoff value of mEASIX-7 for the prediction of day-30 mortality, which was determined to be 2.71 [AUC: 0.747 (0.599-0.896);p=0.021], the study group was divided into two subgroups as low-mEASIX-7 and high-mEASIX7 groups. Probability of OS was significantly higher in the low-mEASIX-7 group compared to high-mEASIX-7 group (37% vs 25.2%; p=0.008; HR: 2.057; 95% CI: 1.208-3.504). Day-30 mortality (2.9% vs 19.4%; p=0.017; HR: 7.028; 95% CI: 1.418-34.836) and day-100 mortality (9% vs 33%; p=0.004; HR: 4.469; 95% CI: 1.619-12.336) were significantly lower in the low-mEASIX-7 group. Furthermore, the probability of NRM was significantly lower in the low-mEASIX-7 group compared to high-mEASIX-7 group (44.8% vs 61.4%; p=0.005; HR: 2.551; 95% CI: 1.318-4.941). Image:Summary/Conclusion: Pretransplant risk assessment is essential to guide the mainstays of the transplant procedure and optimize supportive care measures. In consideration with the basic role of endothelial activation in the development of life threatening complications of alloHCT, mEASIX-7 is indicated to have a predictive prognostic impact on survival and transplant related complications.

Effect of Chloroquine and Hydroxychloroquine on Cytokine Release Syndrome in Patients with COVID-19.

Objective: To assess the effect of chloroquine and hydroxychloroquine on cytokine release syndrome (CRS) in adult patients with coronavirus disease 2019 (COVID-19) having mild to moderate symptoms.Methods: This blinded, placebo-controlled, randomized study was conducted in the Department of Medicine, Pak Emirates Military Hospital Rawalpindi, from June 1-15, 2020. A total of 150 hospitalized patients were enrolled after diagnoses with COVID-19 through reverse transcription polymerase chain reaction (RT-PCR). They were divided into three groups: hydroxychloroquine plus general care (HGC, n=50), chloroquine plus general care (CGC, n=50); and only general care (OGC, n=50). The HGC group received treatment with hydroxychloroquine 400 mg every 12 hours for day one and 200 mg for the next 4 days. The CGC group received treatment with chloroquine 250 mg every 12 hours for 7 days. The OGC group was kept as a control with only general care. After 12 days, the patients were screened for development of CRS through detection of interleukin 6 (IL-6) in serum samples by using Roche cobas e411 electrochemiluminescence immunoassay analyzer.Results: The mean duration from onset of symptoms to randomization was 7.65 days (SD = 3.287 days; range, 2-15 days). The mean age of patients was 37.57 (range 19-63) years. Results showed that out of a total 150 patients, only 10 patients (6%, mean=1.93; CI=1.89-1.97, P=0.651) developed CRS in all study groups. Four patients (8%) developed CRS in the HGC group, 2 patients (4%) in the CGC group, and 4 patients (8%) in the OGC group. There was no significant difference in the mean level of CRS among study groups.Conclusion: Administration of hydroxychloroquine and chloroquine has no effect in reducing the development of CRS in patients with COVID-19 having mild to moderate symptoms.

Cytokine Release Syndrome Following Peripheral Blood Stem Cell Haploidentical Hematopoietic Cell Transplantation with Post-Transplantation Cyclophosphamide

Post-transplantation cyclophosphamide (PTCy) is a safe and efficacious graft-versus-host-disease (GVHD) prophylaxis following hematopoietic cell transplantation (HCT) from a haploidentical (haplo) donor. Cytokine release syndrome (CRS) is a common complication of this platform. Early fever post-haplo-HCT using bone marrow grafts is associated with higher CD3+ cell dose and CRS. However, the impact of CD3+ and CD34+ cell dose on CRS post-haplo-HCT using peripheral blood stem cell (PBSC) grafts is unknown. Our goals were to evaluate the incidence of CRS following PBSC transplantation (PBSCT) and to identify factors that can be modified to prevent the development of severe CRS in this setting. In 271 patients, we investigated factors associated with the development of CRS following haplo-PBSCT and examined the impact of CRS on clinical outcomes. Ninety-three percent of the patients developed CRS of any grade post-haplo-PBSCT. In multivariate analysis, severe CRS (grade 3-4 versus grade 0-1) was associated with higher nonrelapse mortality (hazard ratio [HR], 6.42; 95% confidence interval [CI], 2.68 to 15.39; P < .001), worse 1-year overall survival (HR, 3.40; 95% CI, 1.63 to 7.08; P=.005), and worse disease-free survival (HR, 4.02; 95% CI, 1.99 to 8.08; P < .001). Moderate to severe CRS (grade 2-4) did not impact 1-year relapse or acute GVHD (grade II-IV and III-IV) at 100 days (P=.71 and .19, respectively). Importantly, higher CD3+ cell dose, but not CD34+ cell dose, predicted a higher incidence of grade 2-4 CRS (HR, 1.20; 95% CI,1.07 to 1.36; P=.003) and grade 3-4 CRS (HR, 1.40; 95% CI, 1.05 to 1.86; P=.022). Both older age (HR, 8.57; 95% CI, 1.73 to 42.36; P < .001) and non-total body irradiation-based reduced-intensity conditioning with fludarabine/melphalan (HR, 15.38; 955 CI, 2.06 to 114.67; P < .001) were predictive of grade 3-4 CRS. Overall, we observed that severe CRS (grade 3-4) negatively affected transplantation outcome, and that higher CD3 cell dose was associated with the development of any grade CRS and severe CRS.

Adverse Events Following CAR T-Cell Therapy: A Single Institution Retrospective Analysis of Toxicities Following CAR T-Cell Therapy for Children and Young Adults with Relapsed Refractory B-Cell Acute Lymphoblastic Leukemia

Introduction: CAR T-cells have demonstrated remarkable ability to induce complete remission in patients with relapsed/refractory B-cell acute lymphoblastic leukemia (r/r ALL). This success, however, is tempered by the toxicities associated with CAR T-cell therapy. Much has been published on cytokine release syndrome (CRS), but, to date, a comprehensive profile of specific end organ toxicities secondary to CAR T-cell therapy in the pediatric and young adult population is lacking.Methods: This retrospective, single center study, was performed to characterize the specific adverse events (AEs) experienced by pediatric and young adult patients during the first 30 days following CAR T-cell infusion. AEs graded using Common Terminology Criteria for Adverse Events (CTCAE) were collected from all patients with r/r ALL treated on one of three phase I CAR T-cell trials (CD19, CD22, and CD1922) at the Pediatric Oncology Branch of the National Cancer Institute at the National Institutes of Health from 2012-2020. The primary objective was to determine the incidence of all severe AEs, defined as > grade (Gr) 3 AEs, overall and by organ system, attributed to research or disease. Secondary objectives were to stratify severe AEs based on development of CRS and CRS grade (using ASTCT CRS grading criteria). Descriptive statistics were reported along with comparisons of continuous parameters using Mann-Whitney and binomial parameters using Fischer's exact tests.Results: We reviewed AE data from 134 patients with r/r ALL receiving one of 3 unique CAR T-cell constructs (Table). The median age was 15.2 years (Interquartile range (IQR) 9.5-21.2). The median number of prior therapies was 5 (IQR 3-6) and 57% had received a prior hematopoietic stem cell transplant (HSCT).Amongst the 134 patients, a total of 1747 individual > Gr 3 AEs were experienced by 133 patients (99%) during the first 30 days following CAR infusion (Figure 1A). The median number of > Gr 3 AEs per patient was 10 (IQR 4.8-19).Cytopenias (including neutropenia, thrombocytopenia and anemia) comprised the vast majority of total > Gr 3 AEs (n=983, 56.3%). The most common severe (> Gr 3) AEs were thrombocytopenia (n=433, 24.8%), metabolic abnormalities (i.e. electrolyte derangements) (n=333, 19.1%), neutropenia (n=332, 19%), and anemia (n=218, 12.5%).With exclusion of cytopenias, 764 > Gr 3 AEs were experienced by 111 patients (83%), with a median of 4 (IQR 1-8.3) > Gr 3 AEs per patient. One grade 5 pulmonary AE occurred in the setting of acute respiratory distress syndrome (ARDS). Focusing on non-cytopenia AEs (Figure 1B), metabolic AEs made up 43.6% of AEs; hepatic toxicities (n=115, 15%), febrile neutropenia (n=114, 14.9%), and cardiovascular toxicities (n=59, 7.7%) were the next most frequent.Of the 134 patients, 104 (77.6%) developed CRS. All 30 patients without CRS had at least 1 > Gr 3 AE (median 6, IQR 3-11.3). In contrast, the median number of > Gr 3 AEs in those with CRS was 11.5 (IQR, 6-21.5), (p=0.0021). When stratified by CRS Gr 1-2 versus CRS Gr 3-4 (Figure 2), patients with higher-grade CRS also had a higher median number of > Gr 3 AEs per patient (p= 0.0017).Conclusions: Among 134 children and young adults with r/r ALL receiving phase I CAR T-cells, we found a high incidence (99%) of severe AEs, with a per patient median of 10 (IQR 4.8-19) > Gr 3 AEs. While the majority of > Gr 3 AEs were cytopenias, 17 different categories of AEs were experienced. The development and severity of CRS associated with an increase in the median number of severe AEs per patient. As phase I trials of CAR T-cell therapy expand, it is imperative to understand the full toxicity profile of these therapies. While the definition and refined grading of CRS has helped advance the field, there is a gap in knowledge regarding patient specific end-organ toxicities beyond CRS. Our data help establish a foundation for the full toxicity profile experienced by patients enrolling on phase I CAR T-cell trials. With an emerging role for earlier intervention for CRS, we anticipate that the toxicity burden will decrease. Next steps include characterizing the specific toxicities within each AE category, evaluating duration and time to resolution, distinguishing attribution to research versus disease and studying the impact of earlier use of tocilizumab on toxicity profile. Future directions will incorporate assessment of baseline organ function pre-CAR and its impact on development of post CAR severe AEs. [Display omitted] DisclosuresNo relevant conflicts of interest to declare.

Dynamics and Management of CAR-T Cells Associated Cytopenias: A Single-Center Experience

* Martín-Rojas RM and Bailén R equally contributed to this work.INTRODUCTIONCAR-T cell therapy is approved by the European Medicines Agency (EMA) and the Federal Drugs Administration (FDA) for the treatment of adult patients with relapsed/refractory (R/R) diffuse large B-cell lymphoma (DLBCL) after two or more lines of systemic therapy and for children and adults up to age 25 with relapsed/refractory B-cell acute lymphoblastic leukemia (B-ALL). Prolonged cytopenias have been reported in up to 30-60% of patients undergoing CAR-T cell therapy, but information about its pathophysiology, dynamics and clinical impact is scarce.METHODSWe conducted a retrospective study of consecutive patients undergoing commercial CAR-T cell therapy in our center between June 2019 and March 2021. We analyzed peripheral blood cell counts pre-lymphodepletion, at admission and during the first year of follow-up. This information was correlated with clinical data and analytical parameters. This study was approved by our institutional Ethics Committee and it was performed in compliance with the Declaration of Helsinki. Data were analyzed using IBM SPSS Statistics version 24 and GraphPad Prism version 8.4.3.RESULTSA total of 40 patients were included, 37 with diagnosis of R/R DLBCL and 3 with B-ALL (Table 1). 6-month overall survival was 71% for patients with lymphoma and 33.3% for patients with B-ALL.The dynamics of neutrophil and platelet counts is shown in Figure 1. Median hospitalization duration was 25 days (range: 11-241) and, during this period, 10 patients (25%) required transfusion of 5 or more red cell concentrates (18.9% lymphoma vs. 100% B-ALL; p=0.002), 11 patients (27.5%) required 5 or more platelet transfusions (21.6% lymphoma vs. 100% B-ALL; p=0.003) and 6 patients needed 5 or more doses of G-CSF (13.5% lymphoma vs. 33.3% B-ALL; p=0.3).On day +28 post CAR-T cell therapy, 26 patients (65%) showed persistent profound cytopenias not related with marrow infiltration (absolute neutrophil counts ≤500/μL and/or platelets ≤50000/ μL): a total of 4 patients (15.4%) had neutropenia, 8 patients (31%) thrombopenia and 14 patients (54%) both. 100% of patients with B-ALL maintained aplasia at day +28, with no evidence of disease.Due to persistent cytopenias at discharge, 22 patients (64.7%) received outpatient treatment with G-CSF (20 lymphoma vs. 2 B-ALL; p=0.41), 13 patients (38.2%) received erythropoietin (11 lymphoma vs. 2 B-ALL; p=0.16) and 12 patients (35.3%) were treated with thrombopoietin analogues (10 lymphoma vs. 2 B-ALL; p=0.13). One patient with B-ALL received a boost of selected CD34+ cells from her donor (Table 1).On day +90 post CAR-T cell therapy, 7 patients (26.9%) showed profound cytopenias and, on day +180 it increased to 9 patients (47.4%). None of the 9 patients who were alive at one year follow-up, presented profound cytopenias at this point (Figure 2).Profound cytopenias on day +28 were related to bridging therapy (p=0.04), bone marrow infiltration at diagnosis (p=0.05), higher lymphodepletion doses (p=0.05), evidence of a bulky mass pre-lymphodepletion (p=0.007), development of cytokine release syndrome (CRS) (p=0.012), ICU admission (p=0.07), infectious complications (p=0.008) and having less than 2000/ μL neutrophils pre-lymphodepletion (p=0.04). A multivariate analysis using logistic regression identified higher doses of lymphodepletion (OR 7.57; 95% CI 1.14-50.4; p=0.03) and bone marrow infiltration at diagnosis (OR 7.31; 95% CI 0.97-54.95; p=0.05) as the only independent predictors factors of these cytopenias.Profound cytopenias on day +180 were related to bone marrow infiltration at diagnosis (p=0.02), having received bridging therapy (p=0.05) and lower pre-lymphodepletion lymphocyte counts (p=0.04) and folate levels (p=0.05). None of these variables reached statistical significancy on the multivariate analysis.CONCLUSIONSProfound cytopenias not associated with progression or relapse were a frequent complication after commercial CAR-T cell therapy, with 65% of cases on day +28, being the lymphodepletion dose and bone marrow infiltration at diagnosis independent predictors for its development. Beyond day +28, up to 47% patients showed profound cytopenias. A higher number of patients and longer follow-up are needed to confirm our findings and identify other potential prognosis factors for these cytopenias. [Display omitted] DisclosuresMartín-Rojas: Pfizer: Membership on an entity's Board of Directors or advisory committees; Celgene-BMS: Consultancy, Membership on an entity's Board of Directors or advisory committees; Gilead: Membership on an entity's Board of Directors or advisory committees. Bailen: Pfizer, Kite-Gilead, Gilead: Honoraria. Oarbeascoa: Gilead: Honoraria, Speakers Bureau. Kwon: Novartis, Celgene, Gilead, Pfizer: Consultancy, Honoraria.

Feasibility of Outpatient CAR T Cell Therapy: Experience of a Single Institution

BackgroundChimeric Antigen Receptor (CAR) T cell therapy has emerged as a promising therapeutic option for relapsed/refractory non-Hodgkin lymphoma. However, access to CAR T cell therapy remains limited as CAR T cells are routinely administered in the hospital setting. Hence, there's a growing interest in standardizing outpatient administration of CAR T cells to increase patient access and minimize costs. Here, we describe our institution's experience with outpatient administration of CAR T cells.MethodsIn this retrospective study, we reviewed who received CAR T cell therapy in the outpatient setting at Karmanos Cancer Center between June 2019 and June 2021.Charts were reviewed for age, disease pathology, prior lines of therapy, need for hospitalization within 30 days, development of CRS and/or neurotoxicity, need for ICU admission, need for steroids and/or tocilizumab, length of admission, and disease state at last follow up. All patients received fludarabine and cyclophosphamide as lymphodepletion (LD) therapy day -5 to -3. CAR T cells were infused on day 0. Patients subsequently followed up in clinic daily for 2 weeks and were started on allopurinol, ciprofloxacin, fluconazole, acyclovir and levetiracetam. First response was assessed by FDG PET scan 4 weeks after CAR T cell .ResultsA total of 12 patients received CAR T cells during the study period. All patients had a diagnosis of DLBCL and received Tisagenlecleucel. Median age at CAR T cell therapy was 69.5 years (40-78 years). Median number of prior lines of therapy was (2-3) while 2 patients had received prior stem cell transplantation. Table 1 describes patient characteristics and lines of therapy. Two patients received bridging therapy prior to LD. Overall response rate was 58.3% (complete response-3, partial response-4). Median duration of follow up was 6.7 (0.6-13.8 months). Four patients required subsequent therapy after CAR T cell for disease progression while 9 patients were alive at the time of data cut off. Figure 1 summarizes disease response and follow .Table 2 summarizes complications during follow up. Nine (75%) patients developed anemia (grade 3-4 n=4, 33.3%), 8 (66.7%) developed thrombocytopenia (grade 3-4 n= 3, 37.5%), and 8 (66.7%) developed neutropenia (grade 3-4 n=8, 66.7%). Median time to platelet recovery to >,000 and neutrophil recovery to >500 was 66 days (44-81 days) and 11.5 days (6-65 days), respectively. Three (25%) patients required platelet and red blood cell transfusion support. Six (50%) patients developed cytokine release syndrome (CRS) with median grade 2 (range 1-3, grade 3-4 n=1). Five (5/6) patients required hospitalization, five (5/6) required tocilizumab, and one (1/6) required steroids. One (8.3%) patient developed neurotoxicity of grade 1 severity improved without systemic therapy.Six patients required hospitalization within 30 days of CAR T cell infusion. Median day of admission from CAR T cell infusion was 4 days (range 2-12 days (range 2-12 days, admission within 3 days n=2, admission under observation n=1). Patient characteristics at admission are summarized in table 3. Of these, 5 patients were diagnosed with CRS,1 patient with colitis and none with blood stream infection. Two patients required ICU admission. Median length of hospital admission was 5.5 days (2-9 days). All patients were alive at discharge while 1 patient required subsequent admission within 30 .ConclusionOutpatient administration of Tisagenlecleucel is feasible with low risk of hospital admission within 3 days of infusion. Adoption of outpatient CAR T cell therapy may increase patient access for treatment of DLBCL and diseases such as multiple myeloma while reducing administration costs for this novel therapy. [Display omitted] DisclosuresModi: Genentech: Research Funding; Seagen: Membership on an entity's Board of Directors or advisory committees; MorphoSys: Membership on an entity's Board of Directors or advisory committees. Deol: Kite, a Gilead Company: Consultancy.

Favorable Modulation of Chimeric Antigen Receptor T Cells Safety and Efficacy By the Non-Covalent BTK Inhibitor Vecabrutinib

Favorable Modulation of Chimeric Antigen Receptor T Cells Safety and Efficacy By the Non-Covalent BTK Inhibitor Vecabrutinib

Decreased Chimeric Antigen Receptor T-Cell Efficacy with Severe or Prolonged Post-Infusion Cytopenias

INTRODUCTIONProlonged cytopenias following Chimeric Antigen Receptor (CAR) T-cell therapy are common. The cytopenias are mainly due to the genotoxic effects of conditioning chemotherapy and systemic inflammatory insult to hematopoietic stem and progenitor cells from CAR T-cell activity. Tocilizumab, an anti-IL6 receptor antibody, reduces cytokine release syndrome (CRS), a clinical manifestation of CAR T inflammatory toxicity. We sought to determine if prophylactic tocilizumab can decrease the risk and/or severity of CRS. We secondarily hypothesized that decreasing the inflammatory injury to hematopoietic stem cells could improve bone marrow function after CAR T. Lastly, we analyzed the association between cytopenias and CAR T efficacy generally.METHODSIn this single-institution, retrospective cohort study, we examined all patients who had received axicabtagene ciloleucel for relapsed/refractory diffuse large B cell lymphoma (DLBCL) between March 2018 and April 2021 (Table 1). Each patient was evaluated for prolonged cytopenias, defined as requiring granulocyte-colony stimulating factor (G-CSF), red blood cell or platelet transfusion beyond day 28 after CAR T infusion. After CAR T infusion, no patient was given any anti-lymphoma therapy prior to collection of blood count data. We compared response to CAR T 6 weeks post-infusion, progression-free survival (PFS), and overall survival (OS) for patients with and without prolonged cytopenias. A univariate regression analysis was performed, and between group differences were calculated using Chi-squared, Fisher's exact tests, and Cox Proportional hazard regression model. Kaplan-Meier and log-rank analyses were used to evaluate the PFS and OS. We also compared patients who did and did not receive prophylactic tocilizumab 36 hours after CAR T infusion for differences in prolonged cytopenias, PFS, OS, and development and severity of CRS and neurotoxicity. CRS and neurotoxicity were graded using the ASTCT consensus grading system.RESULTSThe study included 54 patients, 31 (57.4%) met criteria for prolonged cytopenias. 1 (1.9%) patient died of progressive disease prior to day 28 and was excluded from analysis. All patients who died in this study did so on the basis of progressive lymphoma. Likelihood of no response to CAR T at 6 weeks was higher in patients who needed G-CSF support past day 28 (HR 2.20, p = 0.048), had a hemoglobin nadir less than 8 g/dL (HR 2.61, p = 0.031), were still requiring platelet transfusions after day 28 (HR 2.26, p = 0.038), or had a platelet nadir less than 25,000 per µl during the first 28 days (HR 4.01, p = 0.013, Table 2). For patients who had neutrophil counts below the median at day 28, the median PFS was 4.5 months vs. 17.9 months (HR 2.07, p = 0.035) compared to those above the median. In patients with a platelet nadir less than 25,000 per µl or below the median at day 28 (Figure 1), the median PFS was 4.5 months vs. not reached (HR 3.12, p = 0.003) and 3.9 months vs. not reached (HR 3.85, p = 0.0004) respectively. Median OS was 9.44 months in patients who required G-CSF support past day 28 (HR 2.79, p = 0.022) vs. not reached in those who didn't receive G-CSF past day 28. For patients with an ANC below the median on day 28, median OS was 19.87 months vs not reached (HR 2.65, p = 0.022). In patients with a platelet nadir less than 25,000 per µl or below the median at day 28, the median OS were 7.8 months vs not reached (HR 3.72, p = 0.006) and 7.79 months vs not reached (HR 3.39, p = 0.007) respectively. Among patients who received prophylactic tocilizumab, 12 (54.5%) had prolonged bone marrow failure compared to 19 (57.6%) among those who did not (p = 0.82). PFS, OS, and rates and severity of CRS and neurotoxicity did not differ between the prophylactic tocilizumab groups.CONCLUSIONSIn this study of patients with relapsed/refractory aggressive B-cell lymphomas receiving a CD28 domain-containing CAR T product, severe short-term or prolonged cytopenias were associated with an increased risk of lymphoma progression and death. This effect was not ameliorated by administration of prophylactic tocilizumab, which also did not affect the development or severity of CAR T inflammatory toxicities. Further study is required to determine the mechanistic nature of the relationship between post-infusion cytopenias and CAR T efficacy. [Display omitted] DisclosuresNo relevant conflicts of interest to declare.