Efficacy Of Chimeric Antigen Receptor T-cell Therapy Research Articles

Associations of granulocyte colony-stimulating factor with toxicities and efficacy of chimeric antigen receptor T-cell therapy in relapsed or refractory B-cell acute lymphoblastic leukemia

Few studies have reported the associations of granulocyte colony-stimulating factor (G-CSF) with cytokine release syndrome (CRS), neurotoxic events (NEs) and efficacy after chimeric antigen receptor (CAR) T-cell therapy for relapsed or refractory (R/R) B-cell acute lymphoblastic leukemia (B-ALL). We present a retrospective study of 67 patients with R/R B-ALL who received anti-CD19 CAR T-cell therapy, 41 (61.2%) patients received G-CSF (G-CSF group), while 26 (38.8%) did not (non-G-CSF group). Patients had similar duration of grade 3–4 neutropenia between the two groups. The incidences of CRS and NEs were higher in G-CSF group, while no differences in severity were found. Further stratified analysis showed that the incidence and severity of CRS were not associated with G-CSF administration in patients with low bone marrow (BM) tumor burden. None of the patients with low BM tumor burden developed NEs. However, there was a significant increase in the incidence of CRS after G-CSF administration in patients with high BM tumor burden. The duration of CRS in patients who used G-CSF was longer. There were no significant differences in response rates at 1 and 3 months after CAR T-cell infusion, as well as overall survival (OS) between the two groups. In conclusion, our results showed that G-CSF administration was not associated with the incidence or severity of CRS in patients with low BM tumor burden, but the incidence of CRS was higher after G-CSF administration in patients with high BM tumor burden. The duration of CRS was prolonged in G-CSF group. G-CSF administration was not associated with the efficacy of CAR T-cell therapy.

Impact of Frailty on Outcomes after Chimeric Antigen Receptor T Cell Therapy for Patients with Relapsed/Refractory Multiple Myeloma

The literature is limited regarding outcomes in older adults and frail patients receiving BCMA-directed chimeric antigen receptor T cell therapy (CAR-T) for relapsed or refractory multiple myeloma. Here we describe the safety and efficacy of CAR-T in these clinically important subgroups treated in a real-world setting. Frailty was defined as a frail score ≥2 using the simplified frailty index (score based on age + Eastern Cooperative Oncology Group [ECOG] Performance Status + Hematopoietic Cell Transplantation Comorbidity Index [HCT-CI]). Of the 136 patients analyzed (age range, 41 to 81 years), 83 (61%) were considered frail at the time of CAR-T infusion. Compared to the nonfrail group, the frail group had higher proportions of patients with renal insufficiency (18% versus 6%), high-risk cytogenetics (45% versus 35%), extramedullary disease (51% versus 43%), and ECOG Performance Status ≥2 (18% versus 2%), and worse HCT-CI (3 versus 1). Although patients in the frail group had a higher incidence of immune effector cell-associated neurotoxicity syndrome (ICANS) (39% versus 17%), the incidences of all- grade cytokine release syndrome (CRS), as well as high-grade CRS and ICANS, were similar in the 2 groups. With a median follow-up of 7 months, the median progression-free survival was 6.9 months in the frail group versus 11.1 months in the nonfrail group (P = .028). The median overall survival was 14 months in the frail group and was not reached in the nonfrail group (P = .025). This study highlights the tolerable safety and reasonable efficacy of CAR-T for frail myeloma patients in a real-world practice. Although the frail patients did not experience any excessive high-grade toxicities, they did have inferior efficacy outcomes.

Impact of Frailty on Outcomes after CAR T-Cell Therapy for Patients with Relapsed/Refractory Multiple Myeloma

Introduction: Multiple myeloma (MM) is a disease of the elderly with a median age of 69 years at diagnosis. In addition to advanced age, many of these patients are frail with pre-existing comorbidities and have been historically excluded from clinical trials evaluating chimeric antigen receptor (CAR) T-cell therapy for relapsed refractory (RR) MM. It has been shown that chronologic age alone should not be a barrier towards effective treatment modalities including stem cell transplant and CAR T and that instead of age, frailty scores should be incorporated into CAR T screening and eligibility assessments. As there is limited literature on safety and efficacy of CAR T-cell therapy in frail patients, we conducted a multi-center retrospective study to evaluate clinical characteristics and outcomes of frail patients with RRMM who received standard of care CAR T-cell therapy in real-world practice. Methods: Three U.S. academic medical centers contributed data which included patients with RRMM who had received idecabtagene vicleucel (ide-cel) between 8/30/2021 and 05/31/2023. Frailty was defined using the simplified frailty index by Facon et al (score based on age + ECOG performance status + comorbidity index; frail = score ≥2). Descriptive statistics were used to analyze clinical characteristics such as age, performance status, and comorbidities. Response outcomes were evaluated using IMWG criteria. Adverse events were graded based on the ASTCT and CTCAE v5.0 criteria. Key data-points included incidence and severity of cytokine release syndrome (CRS), immune effector cell associated neurotoxicity syndrome (ICANS), infections, treatment-related mortality (TRM), overall response rates (ORR), partial response (PR), very good partial response (VGPR), complete response (CR), progression-free survival (PFS), and overall survival (OS). Results: Of the 104 patients analyzed (age range 41-81), 70 (67%) were considered frail at the time of CAR T-cell infusion. The frail group had a high proportion of patients with renal insufficiency (19% vs 6%), high-risk cytogenetics (46% vs 36%), extramedullary disease (54% vs 47%), performance status ≥2 (20% vs 3%), and worse comorbidity index (median 3 vs 1) but were otherwise similar to the non-frail group (Table 1). While patients in the frail group experienced less CRS (73% vs 88%) and more ICANS (34% vs 18%) when compared to the non-frail group, incidence of grade 3+ CRS and ICANS were similar between the two groups. Rates of infection were also similar between the groups with nearly one-third of the patients experiencing an infection within 6 months post CAR T. With a median follow up of 8 months, best ORR was 83% (37% sCR/CR, 30% VGPR, 16% PR) in the frail group vs 97% (53% sCR/CR, 35% VGPR, 9% PR) in the non-frail group. Median PFS was 6.6 months in the frail group vs 11 months (p=0.062) in non-frail group. Median OS was 14.4 months in the frail group and was not reached (p=0.086) in the non-frail group (Figure 1). TRM was observed in 3 (4%) patients in the frail group. There was no treatment related mortality observed in the non-frail group. Conclusion: A majority of patients treated with standard of care ide-cel for RRMM in this real-world experience were frail by simplified frailty index. While these patients had worse performance status and higher comorbidity burden at the time of CAR T infusion, they did not experience any excessive high-grade toxicities including TRM. When compared to the non-frail group, frail patients had numerically inferior but statistically similar depth and duration of response. This study supports the tolerable safety and reasonable efficacy of CAR T-cell therapy for frail MM patients in a real-world practice and highlights the need to study outcomes in this patient population in larger registry-based data as well as clinical trials.

Efficacy of Bispecific Antibodies Vs CAR-T in the Treatment of Extramedullary Disease and High-Risk Cytogenetics in Relapsed Multiple Myeloma: A Systematic Review and Meta-Analysis

Background: Bispecific antibodies (BsAb) and Chimeric antigen receptor T-cell therapy (CAR-T) have emerged as a promising treatment option for patients with relapsed, refractory multiple myeloma (RRMM) for greater than four previous lines of therapy. The efficacy of these novel drugs in extramedullary disease (EMD) and high-risk cytogenetic abnormalities (HRCA) is relatively less reported. The purpose of this systematic review and meta-analysis is to compare the efficacy of BsAbs vs CAR-T in the treatment of EMD and HRCAs in RRMM. Methods: A systematic literature search was conducted to identify clinical trials that investigated BsAbs and CAR-T therapies in treating RRMM patients using the PubMed, Cochrane, ASH 2022 and ASCO 2023 abstracts using search terms (bispecific antibodies) AND (multiple myeloma), (CAR T cell therapy) AND (multiple myeloma). For BsAbs, our search on PubMed yielded 263 studies. 7 were clinical trials and 5 of these were included. 6 ASH abstracts and one ASCO abstract were also included resulting in a total of 12 studies considered for this meta-analysis. For CAR-T, our search on PubMed and COCHRANE yielded 84 and 20 studies respectively. After screening, we have included 21 studies and 6 ASCO abstracts in final analysis. RStudio Desktop Version 2023.03.0+ 386 was used for statistical analysis. Cochrane-Q test and I² statistic were used to assess the statistical heterogenicity. Fixed effect model was used for low statistical heterogeneity (P > 0.05 in Cochrane-Q test and I² < 50%), while a random effect model was used for high statistical heterogeneity (P < 0.05 in Cochrane-Q test and I² > 50%). Categorical outcomes were summarized by pooled proportion with 95% CI. Subgroup analysis was performed wherever required. P <0.05 was considered statistically significant. Results Bispecific antibodies Overall response rates (ORR) were reported in a study population of 823 patients across 12 studies. The ORR was reported in 4 studies (n=106) for EMD and 4 studies (n=100) for HRCA respectively. The pooled ORR was 0.67 [95% CI; 0.59; 0.76) for the whole group. The pooled ORR was 0.48 (95% CI of 0.31 to 0.65) for EMD and 0.60 (95% CI of 0.51 to 0.70) for HRCA respectively. Subgroup analysis showed that there was a statistically significant difference in overall response rate according to different targets. However, there was no statistically significant difference in the ORR between the drugs with respect to EMD and HRCA. Combination therapy of Teclistamab and Talquetamab has highest ORR and RR in EMD disease compared to other BsABs in a study by Cohen et al. Funnel plot is symmetrical and showed no probability of publication bias for overall response rate for bispecific antibodies with a p-value of 0.676. CAR T cell therapy ORR with CAR-T cell therapy was reported across 27 studies with pooled sample size of 1469. The ORR was reported in 14 studies (n=172) for EMD and 11 studies (n=268) for HRCAs, respectively. The pooled ORR was 0.86 (95% CI of 0.82 to 0.90). The pooled proportion of RR among MM patients with EMD and HRCAs was 0.77 (95% CI of 0.68 to 0.87) and 0.77 (95% CI of 0.69 to 0.86), respectively. Funnel plot asymmetry showed possible publication bias for overall response rate for CAR T cell therapy with p-value of 0.021. Bispecific antibodies vs CAR-T. ORR in the whole cohort (P <0.001), EMD cohort (P <0.001), and HRCA cohort (P <0.046) were found to be significantly higher in CAR-T cell therapy as compared to bispecific antibodies. Conclusion: BsABs and CAR-T cell therapy are effective treatment options for relapsed MM patients.ORR in the whole cohort, EMD cohort, and HRCA cohort were found to be superior with CAR T cell therapy. However, it is difficult to make direct comparisons of pooled estimates of two different therapies. There was no significant difference in EMD and HRCA between the different types of BsAb therapy. Better reporting of EMD responses is urgently needed in published clinical data to know the true effect size and develop strategies to overcome this.

Improving Anti-Tumor Efficacy of CAR T-Cell Therapy for Acute Myeloid Leukemia (AML): Results from a Multi-Drug Interaction Screening Approach

Background: Acute myeloid leukemia (AML) is a hematopoietic malignancy characterized by uncontrolled proliferation and impaired differentiation of myeloid progenitor cells. With a 5-year overall survival of approx. 30%, the prognosis of patients with acute myeloid leukemia remains poor, in particular for those with relapse or refractory disease. The adoptive transfer of T-cells genetically modified to express a chimeric antigen receptor (CAR) have shown impressive remission rates in patients with B-cell lymphoid malignancies. In contrast, CAR T-cell therapy for AML has induced durable remission only in a minority of patients so far, highlighting the need for strategies to improve anti-tumor efficacy and persistence of AML-specific CAR T-cell products. Adapting an established high throughput screening platform, we aimed to identify compounds with the potential to enhance CAR T-cell mediated cytotoxicity through interaction with tumor and/or CAR T-cells. Methods: We established a high throughput platform to determine the cytotoxicity of four different AML-specific CAR T-cell products targeting CD33 (CD33.CD28.41BB.zeta), CD70 (CD27.zeta), CLL1 (CLL1.CD28.zeta) and EMR2 (also known as ADGRE2; EMR2.41BB.zeta) in the presence of 32 compounds at five different concentrations in a 10,000-fold concentration range. CAR T-cells were generated by transduction of activated T-cells derived from peripheral blood mononuclear cells (PBMCs) of three healthy donors with a gamma retroviral vector containing the different CAR constructs. On day 11 after activation, CAR T-cells and non-CAR-transduced control T-cells were incubated with luciferase-expressing target cells at an effector-target ratio of 1:4 in 384-well plates. Viability of target cells cultured with CAR T-cells, control T-cells or in the absence of T-cells was calculated after 24 and 48 hours using a luciferase signal intensity assay. Combinatorial toxicities were calculated with the Bliss Independence model for synergistic effect and the highest single agent model for additive combination effect. Results: In quality analysis, the intensity of luminescence signals in control wells (tumor only, non-CAR-transduced control T-cells) of different plates was similar and principal component analysis (PCA) of samples derived from different days (batches) did not show significant differences ruling out relevant edge or batch effects that could negatively impact the screening results. Of all tested compounds birinapant, a peptidomimetic of second mitochondrial-derived activator of caspases (SMAC) and inhibitor of apoptosis protein (IAP) family proteins and the hypomethylating agent (HMA) decitabine showed the strongest improvement of CAR T cell cytotoxicity in an additive but also in a synergistic manner. These effects were evident in CAR T-cell products derived from all different T cell donors without significant differences. Depending on the structural composition of the CAR construct, the strongest drug-induced improvement of CAR T-cell cytotoxicity was seen either after 24 or 48 hours. The third generation CAR T- cell construct (CD33.CD28.41BB.zeta) showed enhanced cytotoxicity already after 24 hours, whereas significant anti-leukemic efficacy of CD27.zeta, CLL1.CD28.zeta and EMR2.41BB.zeta CAR T-cells became evident at the later 48 hours timepoint. Importantly, co-treatment with birinapant and decitabine particularly enhanced the cytotoxicity of EMR2-specific CAR T-cells which exhibited the lowest baseline anti-tumor efficacy compared to all other CAR constructs highlighting the potential of distinct chemical compounds to improve the functionality of AML-specific CAR T-cells. Conclusion: Our data suggest that high throughput drug interaction screens are a reliable approach to investigate the impact of chemical compounds on the functionality of AML-specific CAR T-cell products. HMA and SMAC mimetics are promising candidates that may potentially enhance the cytotoxicity of CAR T-cells. Ongoing studies are evaluating the effect of HMAs and SMAC mimetics on CAR T-cell proliferation and anti-tumor efficacy against AML cell lines and primary AML patient samples upon serial antigen stimulation. Furthermore, in-depth proteogenomic characterization to identify molecular signatures of enhanced functionality are currently being performed.

TP53 Deficiency in AML Confers Resistance to CAR T-Cells That Can be Overcome By Targeting the Cholesterol or Wnt Pathways

Introduction TP53-mutant acute myeloid leukemia (AML) and myelodysplastic neoplasms (MDS) are distinct clinicogenomic entities characterized by chemotherapy resistance and high relapse rates after allogeneic stem cell transplantation, and thus, represent an unmet clinical need. Chimeric antigen receptor (CAR) T-cell therapy might be a promising therapeutic option for TP53-mutant AML/MDS. However, the AML-intrinsic determinants of response to T-cell-based approaches in AML, in particular the impact of TP53-deficiency, are largely unknown. In the present study, we addressed the biologically and clinically highly relevant question as to whether, and, if so, how TP53 deficiency in AML cells might confer resistance to CAR T-cell therapy. Results We took advantage of recently developed, CRISPR/Cas9-engineered TP53 isogenic AML cell lines harboring TP53 null, missense, or wildtype alleles to exclude other potential genetic confounders of therapy resistance. Flow cytometry-based co-culture assays using these isogenic cell lines together with CAR T-cells targeting the common AML surface antigens CD33, CD371, CD123, and CD117, showed that AML cells harboring TP53 null or missense mutations were relatively resistant to CAR T-cells in vitro. CAR T-cells engaging TP53-deficient leukemia cells proliferated less, upregulated exhaustion markers, displayed increased trogocytosis, and were ultimately unable to control AML cell outgrowth. Live-cell imaging revealed a longer engagement time of CAR T-cells with TP53-deficient AML cells before killing occurred as judged by propidium iodide influx. Immunodeficient mice xenografted with TP53-deficient AML cells and treated with CAR T-cells exhibited significantly shortened survival compared to TP53-wildtype AML controls. Transcriptional profiling revealed that the cholesterol pathway was upregulated in TP53-deficient AML cells under CAR T-cell attack. Simultaneously, CAR T-cells engaging TP53-deficient AML demonstrated a downregulated Wnt pathway, in particular the master regulators of T-cell fate TCF7 and EOMES. Rational pharmacological targeting of either of these pathways, blocking by Simvastatin and activation by BIO-acetoxime, respectively, rescued TP53-deficient AML cell sensitivity to CAR T-cell-mediated killing in vitro. Discussion and Outlook Using a combination of in vitro co-incubation assays, live-cell imaging, gene expression profiling and a therapeutic in vivo model we could demonstrate that TP53 deficiency in AML cells confers relative resistance to CAR T-cell therapy and elucidate some of the underlying molecular mechanisms in leukemia target cells and CAR T-cells. We thus propose a model, in which the intrinsic apoptotic defect in TP53-deficient AML/MDS cells results in a longer duration of the cellular interaction between CAR T-cells and TP53-deficient AML/MDS cells. This longer temporal interaction eventually leads to reduced CAR T-cell proliferation and enhanced CAR T-cell exhaustion with an overall decrease in AML cell killing (figure 1). Furthermore, we identified the cholesterol pathway as a potential therapeutic vulnerability of TP53-deficient AML cells engaged by CAR T-cells, and the Wnt pathway as a promising avenue to enhance the efficacy of CAR T-cell therapy in TP53-deficient AML/MDS. Our data suggest that the combination of CAR T-cell therapies with pharmacological co-interventions - as exemplified in this study - may be a preferable strategy towards more efficacious and tolerable cellular therapies for patients with TP53-mutant myeloid neoplasms.

Loss of p53 Impairs Death Receptor Expression and Confers Resistance to CD19-Directed CAR T-Cell Therapy in B-Cell Precursor Acute Lymphoblastic Leukemia

Background In recent years, new therapy strategies such as the antibody-drug conjugate inotuzumab ozogamicin, the bi-specific T-cell engager blinatumomab, and chimeric antigen receptor (CAR) T-cells have been introduced to salvage relapsed precursor B acute lymphoblastic leukemia (ALL). However, recent evidence indicates that these new therapies are ineffective in TP53-aberrant ALL, although the mechanism remains unclear. TP53 is the most frequently mutated gene in cancer, but in ALL, mutations or deletions affecting TP53 are rare, with an incidence of only 3% at diagnosis. However, at relapse, TP53 aberrations are found in approximately 12% of the patients and predict a very poor outcome. Consequently, relapsed TP53 deleted ALL is now classified as ‘very high risk’. Since p53-mediated apoptosis is an endpoint for many (cytotoxic) drugs, loss of p53 function induces therapy resistance to classical chemotherapeutics. Hence, there is a clear clinical need for more effective strategies to treat TP53 aberrant relapsed ALL. Methods Using CRISPR/Cas9, we introduced frameshift mutations in the TP53 gene to generate isogenic wild type and knockout models in TP53 WT ALL cell lines Nalm6 and RCH-ACV. Additionally, we prepared CD19-directed CAR T-cells with a 4-1BB co-stimulatory domain from three healthy donors by isolating, transducing, and expanding CD4+ and CD8+ T-cells separately. With flow cytometry, we assessed survival of p53 WT and p53 KO leukemic cells in the presence of CD4+ and CD8+ CAR T-cells at a 1:1 CD4:CD8 ratio. Moreover, we performed mRNA profiling by qRT-PCR and cell membrane profiling by flow cytometry to determine how loss of p53 affects CAR T mediated killing. Initial findings in cell lines were then validated in patient-derived xenografts. Results We observed that loss of p53 led to up to a 35% decrease in killing by overnight CAR T treatment in both cell line models (Figure 1A). Although loss of p53 has been linked to reduced cell surface expression of CD19 (Pan et al., 2020, Leukemia), no changes in CD19 expression were observed in response to p53 loss. In search for an explanation for the diminished killing, we performed mRNA profiling and found a reduced expression of death receptors CD95/Fas and DR5/TRAILR2 in p53-deficient cells, which was confirmed at the protein level with flow cytometry (Figure 1B). Indeed, CRISPR/Cas9 mediated loss of CD95/Fas expression in p53 wild type cells reduced CAR T mediated cell killing, consistent with a key role for CD95/Fas in T-cell mediated killing. Conversely, treatment of p53 proficient cells with MDM2 inhibitors induced expression of CD95/Fas and DR5/TRAILR2 (Figure 1B), which translated into enhanced killing of target cells. Most of these observations have already been recapitulated in a diagnosis-relapse pair of patient-derived cells in which the diagnosis was p53wild typeand the relapse was p53 deficient (Figure 1A-B). We observed lower baseline mRNA expression of CD95/Fas and DR5/TRAILR2 in p53-deficient cells, accompanied by a 50% reduction in killing relative to the p53 wild type controls. Conversely, MDM2 inhibition increased death receptor expression only in p53-proficient cells. The ongoing experiments validating enhanced killing after MDM2 inhibition in patient-derived cells will be presented during the meeting. Conclusions Loss of p53 impairs expression of CD95/Fas and DR5/TRAILR2, thereby protecting ALL cells from CAR T induced cell death. In addition, our results indicate that the p53-controlled expression of these receptors may be exploited to increase the efficacy of CAR T-cell therapy in p53-proficient patients.

The Impact of Pre-Existing Autoimmune Disease on the Safety and Efficacy of CAR T-Cell Therapy for Non-Hodgkin Lymphoma

Introduction: Chimeric antigen receptor T-cell therapy (CAR-T) has revolutionized the treatment of non-Hodgkin lymphoma (NHL). Despite having an increased risk of NHL, patients with pre-existing autoimmune disease (AID) were excluded from pivotal CAR-T trials due to concerns that CAR-T may exacerbate AID. As a result, there are limited data on the safety and efficacy of CAR-T for NHL in patients with AID. Interestingly, there is also growing evidence that CAR-T can be therapeutically effective for AID, such as in the treatment of systemic lupus erythematosus (SLE). As CAR-T utilization for NHL increases, it is essential to characterize the safety and efficacy of this potentially curative therapy in patients with AID. This study aimed to evaluate the impact of AID on outcomes in patients treated with commercial CD19-targeted CAR-T for NHL. Methods: Following Institutional Review Board approval, we conducted a retrospective analysis of all patients who were treated with commercial CD19-targeted CAR-T for NHL and had a pre-existing AID across the Mayo Clinic Enterprise (Arizona, Florida, and Minnesota) between January 2018 and May 2023. Variables collected included age, gender, NHL type, AID type, and CAR-T product. Efficacy outcomes, including response rates at 6 and 12 months after CAR-T, were collected. Toxicities, including cytokine release syndrome (CRS) and immune effector cell-associated neurotoxicity syndrome (ICANS), were collected and analyzed. Our chart review for AID included SLE, sarcoidosis, ulcerative colitis, celiac disease, pernicious anemia, Crohn's disease, psoriasis, Sjogren's syndrome, hypothyroidism (Hashimoto's disease), hyperthyroidism (Graves' disease), rheumatoid arthritis (RA), vasculitis, scleroderma, and mixed connective tissue disease (MCTD). Results: A total of 235 patients who received commercial CD19-targeted CAR-T for NHL across the Mayo Clinic Enterprise were identified (Table 1). Of these 235 patients, 27 had a pre-existing AID and 208 did not. The median age was 66 years (range 39-81) for patients with AID and 59 years (range 18-88) for patients without AID. Over half of the patients were male (59% of patients with AID and 51% of patients without AID). The most common NHL type was diffuse large B cell lymphoma (41% of patients with AID and 56% of patients without AID). Most patients received axicabtagene ciloleucel (85% of patients with AID and 84% of patients without AID). The most common AID was hypothyroidism (81%, n=22), although other conditions were also identified, including RA (11%, n=3), SLE (4%, n=1), pulmonary sarcoidosis (4%, n=1), psoriasis (4%, n=1), and MCTD (4%, n=1). Two patients had more than one AID. Median follow-up was 18 months (range 1-36) for patients with AID and 14 months (range 2-49) for patients without AID. Six months after CAR-T, the complete response (CR) rate was 77.2% and 45.1% in patients with AID and without AID, respectively (p=0.0042). Twelve months after CAR-T, the CR rate was 50% and 31.4% in patients with AID and without AID, respectively (p=0.0801). CRS of any grade occurred in 78% and 88% of patients with and without AID, respectively. ICANS of any grade occurred in 41% and 54% of patients with and without AID, respectively. Conclusion: AID did not appear to adversely impact the safety or efficacy of CAR-T for NHL. Limitations of our study include the small number of patients with AID and the fact that the most common AID was hypothyroidism. Larger studies are warranted to confirm these findings. Additional data are needed to characterize the impact of CAR-T for NHL on AID outcomes and to describe the effect of disease-modifying antirheumatic drugs on NHL outcomes after CAR-T.

PET-based radiomics signature can predict durable responses to CAR T-cell therapy in patients with large B-cell lymphoma.

Chimeric antigen receptor (CAR) T-cell therapy is a promising treatment option for relapsed or refractory (R/R) large B-cell lymphoma (LBCL). However, only a subset of patients will present long-term benefit. In this study, we explored the potential of PET-based radiomics to predict treatment outcomes with the aim of improving patient selection for CAR T-cell therapy. We conducted a single-center study including 93 consecutive R/R LBCL patients who received a CAR T-cell infusion from 2018 to 2021, split in training set (73 patients) and test set (20 patients). Radiomics features were extracted from baseline PET scans and clinical benefit was defined based on median progression-free survival (PFS). Cox regression models including the radiomics signature, conventional PET biomarkers and clinical variables were performed for most relevant outcomes. A radiomics signature including 4 PET-based parameters achieved an AUC=0.73 for predicting clinical benefit in the test set, outperforming the predictive value of conventional PET biomarkers (total metabolic tumor volume [TMTV]: AUC=0.66 and maximum standardized uptake value [SUVmax]: AUC=0.59). A high radiomics score was also associated with longer PFS and OS in the multivariable analysis. In conclusion, the PET-based radiomics signature predicted efficacy of CAR T-cell therapy and outperformed conventional PET biomarkers in our cohort of LBCL patients.

Axicabtagene Ciloleucel in Combination with the 4-1BB Agonist Utomilumab in Patients with Relapsed/Refractory Large B-Cell Lymphoma: Phase 1 Results from ZUMA-11.

Chimeric antigen receptor (CAR) T-cell therapies have shown clinical benefit for patients with relapsed/refractory (R/R) large B-cell lymphoma (LBCL), yet approximately 60% of patients do not respond or eventually relapse. We investigated the safety and feasibility of the CD19-directed CAR T-cell therapy axicabtagene ciloleucel (axi-cel) in combination with the 4-1BB agonist antibody utomilumab as an approach to improve efficacy of CAR T-cell therapy. In phase 1 of the single-arm ZUMA-11 trial, patients with R/R LBCL received a single axi-cel infusion (target dose, 2 × 106 cells/kg) plus utomilumab 10 to 200 mg intravenously every 4 weeks for up to 6 months in a dose-escalation design. The primary endpoint was incidence of dose-limiting toxicities (DLT) with utomilumab. Key secondary endpoints were safety, antitumor activity, pharmacokinetics, and pharmacodynamics. No DLTs were observed among patients treated with axi-cel and utomilumab (n = 12). Grade ≥3 adverse events occurred in 10 patients (83%); none were Grade ≥3 cytokine release syndrome or neurologic events. The objective response rate was 75% and seven patients (58%) had a complete response. Peak CAR T-cell levels increased in a utomilumab dose-dependent manner up to 100 mg. Patients who received utomilumab 100 mg had persistently increased CAR T cells on days 57 to 168 compared with other dose levels. Utomilumab was associated with dose-dependent increases in IL2, IFNγ, and IL10. Utomilumab-mediated 4-1BB agonism combined with axi-cel therapy had a manageable safety profile. Dual 4-1BB and CD28 costimulation is a feasible therapeutic approach that may enhance CAR T-cell expansion in patients with LBCL.

Neutralizing IFNγ improves safety without compromising efficacy of CAR-T cell therapy in B-cell malignancies

Chimeric antigen receptor T (CAR-T) cell therapy may achieve long-lasting remission in patients with B-cell malignancies not responding to conventional therapies. However, potentially severe and hard-to-manage side effects, including cytokine release syndrome (CRS), neurotoxicity and macrophage activation syndrome, and the lack of pathophysiological experimental models limit the applicability and development of this form of therapy. Here we present a comprehensive humanized mouse model, by which we show that IFNγ neutralization by the clinically approved monoclonal antibody, emapalumab, mitigates severe toxicity related to CAR-T cell therapy. We demonstrate that emapalumab reduces the pro-inflammatory environment in the model, thus allowing control of severe CRS and preventing brain damage, characterized by multifocal hemorrhages. Importantly, our in vitro and in vivo experiments show that IFNγ inhibition does not affect the ability of CD19-targeting CAR-T (CAR.CD19-T) cells to eradicate CD19+ lymphoma cells. Thus, our study provides evidence that anti-IFNγ treatment might reduce immune related adverse effect without compromising therapeutic success and provides rationale for an emapalumab-CAR.CD19-T cell combination therapy in humans.

Data driven model discovery and interpretation for CAR T-cell killing using sparse identification and latent variables.

In the development of cell-based cancer therapies, quantitative mathematical models of cellular interactions are instrumental in understanding treatment efficacy. Efforts to validate and interpret mathematical models of cancer cell growth and death hinge first on proposing a precise mathematical model, then analyzing experimental data in the context of the chosen model. In this work, we present the first application of the sparse identification of non-linear dynamics (SINDy) algorithm to a real biological system in order discover cell-cell interaction dynamics in in vitro experimental data, using chimeric antigen receptor (CAR) T-cells and patient-derived glioblastoma cells. By combining the techniques of latent variable analysis and SINDy, we infer key aspects of the interaction dynamics of CAR T-cell populations and cancer. Importantly, we show how the model terms can be interpreted biologically in relation to different CAR T-cell functional responses, single or double CAR T-cell-cancer cell binding models, and density-dependent growth dynamics in either of the CAR T-cell or cancer cell populations. We show how this data-driven model-discovery based approach provides unique insight into CAR T-cell dynamics when compared to an established model-first approach. These results demonstrate the potential for SINDy to improve the implementation and efficacy of CAR T-cell therapy in the clinic through an improved understanding of CAR T-cell dynamics.

Associations of granulocyte colony-stimulating factor with toxicities and efficacy of chimeric antigen receptor T-cell therapy in relapsed or refractory multiple myeloma

Background aimsFew studies have reported the associations of granulocyte colony-stimulating factor (G-CSF) with cytokine release syndrome (CRS), neurotoxic events (NEs) and efficacy after chimeric antigen receptor (CAR) T-cell therapy for relapsed or refractory (R/R) multiple myeloma (MM). We present a retrospective study performed on 113 patients with R/R MM who received single anti-BCMA CAR T-cell, combined with anti-CD19 CAR T-cell or anti-CD138 CAR T-cell therapy. MethodsEight patients were given G-CSF after successful management of CRS, and no CRS re-occurred thereafter. Of the remaining 105 patients that were finally analyzed, 72 (68.6%) received G-CSF (G-CSF group), and 33 (31.4%) did not (non G-CSF group). We mainly analyzed the incidence and severity of CRS or NEs in two groups of patients, as well as the associations of G-CSF timing, cumulative dose and cumulative time with CRS, NEs and efficacy of CAR T-cell therapy. ResultsBoth groups of patients had similar duration of grade 3–4 neutropenia, and the incidence and severity of CRS or NEs.There were also no differences in the incidence and severity of CRS or NEs between patients with the timing of G-CSF administration ≤3 days and those >3 days after CAR T-cell infusion. The incidence of CRS was greater in patients receiving cumulative doses of G-CSF >1500 μg or cumulative time of G-CSF administration >5 days. Among patients with CRS, there was no difference in the severity of CRS between patients who used G-CSF and those who did not. The duration of CRS in anti-BCMA and anti-CD19 CAR T-cell–treated patients was prolonged after G-CSF administration. There were no significant differences in the overall response rate at 1 and 3 months between the G-CSF group and the non–G-CSF group. ConclusionsOur results showed that low-dose or short-time use of G-CSF was not associated with the incidence or severity of CRS or NEs, and G-CSF administration did not influence the antitumor activity of CAR T-cell therapy.

Applications and current challenges of chimeric antigen receptor T cells in treating high-grade gliomas in adult and pediatric populations.

High-grade gliomas (HGGs) continue to be some of the most devastating diseases in the USA. Despite extensive efforts, the survival of HGG patients has remained relatively stagnant. Chimeric antigen receptor (CAR) T-cell immunotherapy has recently been studied in the context of improving these tumors' clinical outcomes. HGG murine models treated with CAR T cells targeting tumor antigens have shown reduced tumor burden and longer overall survival than models without treatment. Subsequent clinical trials investigating the efficacy of CAR T cells have further shown that this therapy could be safe and might reduce tumor burden. However, there are still many challenges that need to be addressed to optimize the safety and efficacy of CAR T-cell therapy in treating HGG patients.

Challenges for CAR-T cell therapy in multiple myeloma: overcoming the tumor microenvironment

Chimeric antigen receptor T (CAR-T) cell therapy has shown promising efficacy in multiple myeloma (MM) patients, leading to FDA approval of two B cell maturation antigen (BCMA)-specific CAR-T cell therapies (ide-cel and cilta-cel). Despite the remarkable response rates and response depth of MM patients to CAR-T cell therapy, patients inevitably relapse. A growing body of evidence suggests that the activity of CAR-T cells is affected by the immunosuppressive tumor microenvironment (TME). In this review we have summarized the main challenges that CAR-T cells face in the TME, including various immunosuppressive cells, structural components, hypoxia, nutrient starvation, and metabolism. Moreover, we also discussed some candidate strategies for CAR-T cell therapy to overcome immunosuppressive TME and improve the efficacy of CAR-T cell therapy in the treatment of MM.

Chimeric Antigen Receptor T Cells: Toxicity and Management Considerations

Chimeric Antigen Receptor T Cells: Toxicity and Management Considerations

Efficacy, Safety, and Challenges of CAR T-Cells in the Treatment of Solid Tumors.

Immunotherapy has been the fifth pillar of cancer treatment in the past decade. Chimeric antigen receptor (CAR) T-cell therapy is a newly designed adoptive immunotherapy that is able to target and further eliminate cancer cells by engaging with MHC-independent tumor-antigens. CAR T-cell therapy has exhibited conspicuous clinical efficacy in hematological malignancies, but more than half of patients will relapse. Of note, the efficacy of CAR T-cell therapy has been even more disappointing in solid tumors. These challenges mainly include (1) the failures of CAR T-cells to treat highly heterogeneous solid tumors due to the difficulty in identifying unique tumor antigen targets, (2) the expression of target antigens in non-cancer cells, (3) the inability of CAR T-cells to effectively infiltrate solid tumors, (4) the short lifespan and lack of persistence of CAR T-cells, and (5) cytokine release syndrome and neurotoxicity. In combination with these characteristics, the ideal CAR T-cell therapy for solid tumors should maintain adequate T-cell response over a long term while sparing healthy tissues. This article reviewed the status, clinical application, efficacy, safety, and challenges of CAR T-cell therapies, as well as the latest progress of CAR T-cell therapies for solid tumors. In addition, the potential strategies to improve the efficacy of CAR T-cells and prevent side effects in solid tumors were also explored.

The IAP antagonist birinapant enhances chimeric antigen receptor T cell therapy for glioblastoma by overcoming antigen heterogeneity

Antigen heterogeneity that results in tumor antigenic escape is one of the major obstacles to successful chimeric antigen receptor (CAR) Tcell therapies in solid tumors including glioblastoma multiforme (GBM). To address this issue and improve the efficacy of CAR Tcell therapy for GBM, we developed an approach that combines CAR Tcells with inhibitor of apoptosis protein (IAP) antagonists, a new class of small molecules that mediate the degradation of IAPs, to treat GBM. Here, we demonstrated that the IAP antagonist birinapant could sensitize GBM cell lines and patient-derived primary GBM organoids to apoptosis induced by CAR Tcell-derived cytokines, such as tumor necrosis factor. Therefore, birinapant could enhance CAR Tcell-mediated bystander death of antigen-negative GBM cells, thus preventing tumor antigenic escape in antigen-heterogeneous tumor models invitro and invivo. In addition, birinapant could promote the activation of NF-κB signaling pathways in antigen-stimulated CAR Tcells, and with a birinapant-resistant tumor model we showed that birinapant had no deleterious effect on CAR Tcell functions invitro and invivo. Overall, we demonstrated the potential of combining the IAP antagonist birinapant with CAR Tcells as a novel and feasible approach to overcoming tumor antigen heterogeneity and enhancing CAR Tcell therapy forGBM.

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

Novel technologies for improving the safety and efficacy of CAR-T cell therapy.

Chimeric antigen receptor-T (CAR-T) cell therapy has shown significant therapeutic efficacy in the treatment of hematological B-cell malignancies. However, the efficacy of CAR-T cell therapy against solid tumors is limited due to the heterogeneity of tumor antigens and the immunosuppressive tumor microenvironment. Therefore, there is strong demand for novel technologies to improve the efficacy of CAR-T cell therapy. In addition, as CAR-T cells often cause severe side effects, systems to control the activity of CAR-T cells so as to avoid or lessen the occurrence and intensity of these side effects are needed. Here, we describe recently emerging approaches to enhance and/or regulate CAR-T cell functions. These approaches have led to the development of CAR-T therapies with improved efficacy and safety, which are expected to be clinically applied to a variety of cancer types in combination with other therapies, such as immune checkpoint inhibitors, chemotherapy, molecular targeted drugs, and radiation therapy.