CD19-directed Chimeric Antigen Receptor T-cell Research Articles

TNFR2 As a Target to Improve CD19-Directed CART Cell Fitness and Antitumor Activity in Large B Cell Lymphoma

TNFR2 As a Target to Improve CD19-Directed CART Cell Fitness and Antitumor Activity in Large B Cell Lymphoma

Safety and Efficacy of FT596, a First-in-Class, Multi-Antigen Targeted, Off-the-Shelf, iPSC-Derived CD19 CAR NK Cell Therapy in Relapsed/Refractory B-Cell Lymphoma

Safety and Efficacy of FT596, a First-in-Class, Multi-Antigen Targeted, Off-the-Shelf, iPSC-Derived CD19 CAR NK Cell Therapy in Relapsed/Refractory B-Cell Lymphoma

Adverse Cardiovascular and Pulmonary Events Associated With Chimeric Antigen Receptor T-Cell Therapy

BackgroundPivotal trials of chimeric antigen receptor T-cell (CAR-T) have identified common toxicities but may have been underpowered to detect cardiovascular and pulmonary adverse events (CPAEs). ObjectivesThis study sought to investigate CPAEs associated with commercial CD19-directed CAR-T therapy. MethodsIn this retrospective, pharmacovigilance study, the authors used the Food and Drug Administration adverse event reporting system to identify CPAEs associated with axicabtagene-ciloleucel and tisagenlecleucel. The authors evaluated disproportionate reporting by the reporting odds ratio (ROR) and the lower bound of the information component 95% credibility interval (IC025 >0 is deemed significant). Significant associations were further adjusted to age and sex (adj.ROR). ResultsThe authors identified CAR-T reports of 2,657 patients, including 546 CPAEs (20.5%). CPAEs overlapped with cytokine release syndrome in 68.3% (373 of 546) of the reports. Compared with the full database, CAR-T was associated with overreporting of tachyarrhythmias (n = 74 [2.8%], adj.ROR = 2.78 [95% CI: 2.21-3.51]), cardiomyopathy (n = 69 [2.6%], adj.ROR = 3.51 [2.42-5.09]), pleural disorders (n = 46 [1.7%], adj.ROR = 3.91 [2.92-5.23]), and pericardial diseases (n = 11 [0.4%], adj.ROR = 2.26 [1.25-4.09], all IC025 >0). Venous thromboembolic events (VTEs) were associated only with axicabtagene-ciloleucel therapy (n = 28 [1.6%], adj.ROR = 1.80 [1.24-2.62], IC025 >0). Atrial fibrillation (n = 55) was the leading tachyarrhythmia, followed by ventricular arrhythmias (n = 14). Tachyarrhythmias and VTEs were reported more often following axicabtagene-ciloleucel than tisagenlecleucel in an age- and sex-adjusted model (adj.ROR = 1.82 [1.04-3.18] and adj.ROR = 2.86 [1.18-6.93], respectively). Finally, the fatality rate of CPAEs was 30.9%. ConclusionsIn this largest post-marketing study to date, the authors identified an association between CAR-T and various CPAEs, including tachyarrhythmias, cardiomyopathy, pericardial and pleural disorders, and VTEs. These findings should be considered in the multidisciplinary assessment for and monitoring of CAR-T therapy recipients.

CAR T cells for the long run in aggressive B-cell lymphoma.

Since first being reported in 2010, 1 Kochenderfer JN Wilson WH Janik JE et al. Eradication of B-lineage cells and regression of lymphoma in a patient treated with autologous T cells genetically engineered to recognize CD19. Blood. 2010; 116: 4099-4102 Crossref PubMed Scopus (912) Google Scholar CD19-directed chimeric antigen receptor (CAR) T cells have led a revolution in the treatment of B-cell non-Hodgkin lymphomas. The US Food and Drug Administration have approved three CAR T-cell products for the treatment of relapsed or refractory aggressive B-cell lymphomas: tisagenlecleucel, axicabtagene ciloleucel, and lisocabtagene maraleucel. All three showed high rates of complete responses in patients with refractory disease in pivotal trials (37 [40%] of 93, 2 Schuster SJ Bishop MR Tam CS et al. Tisagenlecleucel in adult relapsed or refractory diffuse large B-cell lymphoma. N Engl J Med. 2019; 380: 45-56 Crossref PubMed Scopus (1179) Google Scholar 59 [58%] of 101, 3 Locke FL Ghobadi A Jacobson CA et al. Long-term safety and efficacy of axicabtagene ciloleucel in refractory large B-cell lymphoma (ZUMA-1): a single-arm, multicentre, phase 1–2 trial. Lancet Oncol. 2019; 20: 31-42 Summary Full Text Full Text PDF PubMed Scopus (693) Google Scholar and 136 [53%] of 256, 4 Abramson JS Palomba ML Gordon LI et al. Lisocabtagene maraleucel for patients with relapsed or refractory large B-cell lymphomas (TRANSCEND NHL 001): a multicentre seamless design study. Lancet. 2020; 396: 839-852 Summary Full Text Full Text PDF PubMed Scopus (271) Google Scholar respectively), taking into account different patient selection and trial designs in each study. In parallel, real-world data have emerged for these products, showing similar overall responses of 61·8% (95% CI 53·6–69·6) for tisagenlecleucel and 70% (61–78) for axicabtagene ciloleucel, and complete responses in 60 (39%) of 152 patients for tisagenlecleucel and 61 (50%) of 122 patients for axicabtagene ciloleucel. 5 Pasquini MC Hu ZH Curran K et al. Real-world evidence of tisagenlecleucel for pediatric acute lymphoblastic leukemia and non-Hodgkin lymphoma. Blood Adv. 2020; 4: 5414-5424 Crossref PubMed Scopus (71) Google Scholar , 6 Jacobson CA Hunter BD Redd R et al. Axicabtagene ciloleucel in the non-trial setting: outcomes and correlates of response, resistance, and toxicity. J Clin Oncol. 2020; 38: 3095-3106 Crossref PubMed Scopus (72) Google Scholar Real-world studies have supported the efficacy and safety of CD19-directed CAR T-cell therapies, including in many patients who would not have been eligible for the pivotal clinical trials. Among patients treated with axicabtagene ciloleucel in the ZUMA-1 study 7 Jacobson C Locke FL Ghobadi A et al. Long-term survival and gradual recovery of B cells in patients with refractory large B cell lymphoma treated with axicabtagene ciloleucel (axi-cel). Blood. 2020; 136: 40-42 Google Scholar with at least 4 years of follow-up (median follow-up 51·1 months), the median overall survival was 25·8 months, and the 4-year estimated overall survival was 44%. The reported duration of follow-up in the JULIET study was relatively short until now. Long-term clinical outcomes of tisagenlecleucel in patients with relapsed or refractory aggressive B-cell lymphomas (JULIET): a multicentre, open-label, single-arm, phase 2 studyTisagenlecleucel shows durable activity and manageable safety profiles in adult patients with relapsed or refractory aggressive B-cell lymphomas. For patients with large B-cell lymphomas that are refractory to chemoimmunotherapy or relapsing after second-line therapies, tisagenlecleucel compares favourably with respect to risk–benefit relative to conventional therapeutic approaches (eg, salvage chemotherapy). Full-Text PDF

CD19-targeted chimeric antigen receptor T-cell therapy for CNS relapsed or refractory acute lymphocytic leukaemia: a post-hoc analysis of pooled data from five clinical trials

CNS relapse of acute lymphocytic leukaemia is difficult to treat. Durable remissions of relapsed or refractory B-cell acute lymphocytic leukaemia have been observed following treatment with CD19-directed chimeric antigen receptor (CAR) T cells; however, most trials have excluded patients with active CNS disease. We aimed to assess the safety and activity of CAR T-cell therapy in patients with a history of CNS relapsed or refractory B-cell acute lymphocytic leukaemia. In this post-hoc analysis, we included 195 patients (aged 1-29 years; 110 [56%] male and 85 [44%] female) with relapsed or refractory CD19-positive acute lymphocytic leukaemia or lymphocytic lymphoma from five clinical trials (Pedi CART19, 13BT022, ENSIGN, ELIANA, and 16CT022) done at the Children's Hospital of Philadelphia (Philadelphia, PA, USA), in which participants received CD19-directed CAR T-cell therapy between April 17, 2012, and April 16, 2019. The trials required control of CNS disease at enrolment and infusion and excluded treatment in the setting of acute neurological toxic effects (>grade 1 in severity) or parenchymal lesions deemed to increase the risk of neurotoxicity. 154 patients from Pedi CART19, ELIANA, ENSIGN, and 16CT022 received tisagenlecleucel and 41 patients from the 13BT022 trial received the humanised CD19-directed CAR, huCART19. We categorised patients into two strata on the basis of CNS status at relapse or within the 12 months preceding CAR T-cell infusion-either CNS-positive or CNS-negative disease. Patients with CNS-positive disease were further divided on the basis of morphological bone marrow involvement-either combined bone marrow and CNS involvement, or isolated CNS involvement. Endpoints were the proportion of patients with complete response at 28 days after infusion, Kaplan-Meier analysis of relapse-free survival and overall survival, and the incidence of cytokine release syndrome and neurotoxicity. Of all 195 patients, 66 (34%) were categorised as having CNS-positive disease and 129 (66%) as having CNS-negative disease, and 43 (22%) were categorised as having isolated CNS involvement. The median length of follow-up was 39 months (IQR 25-49) in the CNS-positive stratum and 36 months (18-49) in the CNS-negative stratum. The proportion of patients in the CNS-positive stratum with a complete response at 28 days after infusion was similar to that in the CNS-negative stratum (64 [97%] of 66 vs 121 [94%] of 129; p=0·74), with no significant difference in relapse-free survival (60% [95% CI 49-74] vs 60% [51-71]; p=0·50) or overall survival (83% [75-93] vs 71% [64-79]; p=0·39) at 2 years between the two groups. Overall survival at 2 years was significantly higher in patients with isolated CNS involvement compared with those with bone marrow involvement (91% [82-100] vs 71% [64-78]; p=0·046). The incidence and severity of neurotoxicity (any grade, 53 [41%] vs 38 [58%]; grade 1, 24 [19%] vs 20 [30%]; grade 2, 14 [11%] vs 10 [15%]; grade 3, 12 [9%] vs 6 [9%], and grade 4, 3 [2%] vs 2 [3%]; p=0·20) and cytokine release syndrome (any grade, 110 [85%] vs 53 [80%]; grade 1, 12 [9%] vs 2 [3%]; grade 2, 61 [47%] vs 38 [58%]; grade 3, 18 [14%] vs 7 [11%] and grade 4, 19 [15%] vs 6 [9%]; p=0·26) did not differ between the CNS-negative and the CNS-positive disease strata. Tisagenlecleucel and huCART19 are active at clearing CNS disease and maintaining durable remissions in children and young adults with CNS relapsed or refractory B-cell acute lymphocytic leukaemia or lymphocytic lymphoma, without increasing the risk of severe neurotoxicity; although care should be taken in the timing of therapy and disease control to mitigate this risk. These preliminary findings support the use of these CAR T-cell therapies for patients with CNS relapsed or refractory B-cell acute lymphocytic leukaemia. Children's Hospital of Philadelphia Frontier Program.

CD19-directed CAR T-cell therapy for treatment of primary CNS lymphoma

AbstractCD19-directed chimeric antigen receptor (CD19CAR) T-cell therapy has been successful in treating several B-cell lineage malignancies, including B-cell non-Hodgkin lymphoma (NHL). This modality has not yet been extended to NHL manifesting in the central nervous system (CNS), primarily as a result of concerns for potential toxicity. CD19CAR T cells administered IV are detectable in cerebrospinal fluid (CSF), suggesting that chimeric antigen receptor (CAR) T cells can migrate from the periphery into the CNS, where they can potentially mediate antilymphoma activity. Here, we report the outcome of a subset of patients with primary CNS lymphoma (PCNSL; n = 5) who were treated with CD19CAR T cells in our ongoing phase 1 clinical trial. All patients developed grade ≥ 1 cytokine release syndrome and neurotoxicity post-CAR T-cell infusion; toxicities were reversible and tolerable, and there were no treatment-related deaths. At initial disease response, 3 of 5 patients (60%; 90% confidence interval, 19-92%) seemed to achieve complete remission, as indicated by resolution of enhancing brain lesions; the remaining 2 patients had stable disease. Although the study cohort was small, we demonstrate that using CD19CAR T cells to treat PCNSL can be safe and feasible. This trial was registered at www.clinicaltrials.gov as #NCT02153580.

A novel and efficient tandem CD19- and CD22-directed CAR for B cell ALL

CD19-directed chimeric antigen receptor (CAR) Tcells have yielded impressive response rates in refractory/relapse B cell acute lymphoblastic leukemia (B-ALL); however, most patients ultimately relapse due to poor CAR Tcell persistence or resistance of either CD19+ or CD19- B-ALL clones. CD22 is a pan-B marker whose expression is maintained in both CD19+ and CD19- relapses. CD22-CAR Tcells have been clinically used in B-ALL patients, although relapse also occurs. Tcells engineered with a tandem CAR (Tan-CAR) containing in a single construct both CD19 and CD22 scFvs may be advantageous in achieving higher remission rates and/or preventing antigen loss. We have generated and functionally validated using cutting-edge assays a 4-1BB-based CD22/CD19 Tan-CAR using in-house-developed novel CD19 and CD22 scFvs. Tan-CAR-expressing Tcells showed similar invitro expansion to CD19-CAR Tcells with no increase in tonic signaling. CRISPR-Cas9-edited B-ALL cells confirmed the bispecificity of the Tan-CAR. Tan-CAR was as efficient as CD19-CAR invitro and invivo using B-ALL cell lines, patient samples, and patient-derived xenografts (PDXs). Strikingly, the robust antileukemic activity of the Tan-CAR was slightly more effective in controlling the disease in long-term follow-up PDX models. This Tan-CAR construct warrants a clinical appraisal to test whether simultaneous targeting of CD19 and CD22 enhances leukemia eradication and reduces/delays relapse rates and antigen loss.

ABCL-022: LOTIS-2 Follow-Up Analysis: Updated Results from a Phase 2 Study of Loncastuximab Tesirine (Lonca) in Relapsed or Refractory Diffuse Large B-Cell Lymphoma

Context Patients with relapsed/refractory diffuse large B-cell lymphoma (R/R DLBCL) who are ineligible for, or relapse after, salvage chemotherapy/stem cell transplant (SCT) have a poor prognosis. Lonca comprises a humanized anti-CD19 antibody conjugated to a potent pyrrolobenzodiazepine dimer toxin. Objective To assess updated efficacy and safety findings from a Phase 2 study evaluating Lonca in patients with R/R DLBCL (LOTIS-2; NCT03589469). Design Multicenter, open-label, single-arm Phase 2 study in adult patients (≥18 years) with pathologically defined R/R DLBCL and ≥2 prior systemic treatments. Intervention Lonca (150 µg/kg every 3 weeks [Q3W] for 2 cycles; 75 µg/kg Q3W thereafter). Main Outcomes Measures Primary efficacy endpoint: Overall response rate (ORR), assessed by central review. Secondary efficacy endpoints: Duration of response (DoR), progression-free survival (PFS), and overall survival (OS). Safety analyses: Treatment-emergent adverse events (TEAEs). Follow-up period: Q12W for ≤3 years after end of treatment. Results 145 patients with R/R DLBCL received ≥1 Lonca dose. Median age was 66 years (range 23–94). Patients received a median of 3 prior therapies (range 2–7). At data cut-off (October 26, 2020, ≥12 months since first dose), 2 patients continued treatment. Patients received a mean of 4.6 Lonca cycles (std 4.1; range 1–22). ORR was 48.3% (complete response [CR]: 24.8%; partial response [PR]: 23.4%). Median DoR was 12.6 months for patients with CR or PR (n=70); not reached for patients with CR. Median PFS and OS were 4.9 and 9.5 months, respectively. Post-Lonca treatment, 15 patients received CD19-directed chimeric antigen receptor T-cell therapy with an investigator-assessed ORR of 46.7%, and 11 patients proceeded to SCT as consolidation after Lonca response. Most common (≥25.0%) all-grade TEAEs were increased gamma-glutamyltransferase (41.4%), neutropenia (40.0%), thrombocytopenia (33.1%), fatigue (27.6%), and anemia (26.2%). Grade ≥3 TEAEs occurred in 107 (73.8%) patients. Treatment-related TEAEs leading to treatment discontinuation and dose delays occurred in 26 (17.9%) and 62 (42.8%) patients, respectively. Conclusions After longer follow-up of patients in LOTIS-2, durable responses to Lonca continue to be observed in heavily pre-treated patients with R/R DLBCL. No new safety concerns occurred. Research funding ADC Therapeutics SA.

CAR T-cell Therapy in Indolent Lymphoma

Introduction CD19 directed chimeric antigen receptor (CAR) T-cell therapy has had a transformative impact on the natural history of chemotherapy refractory aggressive B-cell non-Hodgkin lymphoma (B-NHL) and B-cell acute lymphoblastic leukemia (B-ALL), inducing long-term remissions in 40–50% of patients.1–5 It does this, however, at the expense of both financial and clinical toxicity. But the cost and risk of care in the absence of CAR T-cells in these instances outweighs the risk of the therapy itself, and so it has broadly been accepted as a standard of care for these patients. Moving CD19 directed CAR T-cell therapy into the slower growing, but historically incurable, indolent B-NHLs has the potential to challenge this balance between risks and benefits. Will CAR T-cells offer definitive therapy for these otherwise incurable diseases? If not, will CAR T-cells positively affect long-term survival over alternative therapies? The answer to these questions will determine how oncologists weigh the financial and clinical costs against the therapeutic benefits.

Dynamics of Measurable Disease at Remission Determines Survival in Patients (Pts) with Philadelphia Chromosome Negative B-Cell Acute Lymphoblastic Leukemia (ALL)

Dynamics of Measurable Disease at Remission Determines Survival in Patients (Pts) with Philadelphia Chromosome Negative B-Cell Acute Lymphoblastic Leukemia (ALL)

CD19 CAR T cells for adults with relapsed or refractory acute lymphoblastic leukaemia

CD19-directed chimeric antigen receptor (CAR) T cells first showed potency in adults with chronic lymphocytic leukaemia 1 Porter DL Levine BL Kalos M Bagg A June CH Chimeric antigen receptor-modified T cells in chronic lymphoid leukemia. N Engl J Med. 2011; 365: 725-733 Crossref PubMed Scopus (2417) Google Scholar and with acute lymphoblastic leukaemia 2 Brentjens RJ Davila ML Riviere I et al. CD19-targeted T cells rapidly induce molecular remissions in adults with chemotherapy-refractory acute lymphoblastic leukemia. Sci Transl Med. 2013; 5177ra38 Crossref PubMed Scopus (1390) Google Scholar a decade ago, but clinical development of CAR T cells in these two disease populations stalled. Chronic lymphocytic leukaemia did not respond to CAR T cells as frequently as hoped, in part because of challenges with making the product from patients whose T cells were not as fit, either due to the underlying disease or exposure to years of chemotherapy. 3 Porter DL Hwang WT Frey NV et al. Chimeric antigen receptor T cells persist and induce sustained remissions in relapsed refractory chronic lymphocytic leukemia. Sci Transl Med. 2015; 7303ra139 Crossref PubMed Scopus (1024) Google Scholar , 4 Frey NV Gill S Hexner EO et al. Long-term outcomes from a randomized dose optimization study of chimeric antigen receptor modified T cells in relapsed chronic lymphocytic leukemia. J Clin Oncol. 2020; 38: 2862-2871 Crossref PubMed Scopus (36) Google Scholar In adults with acute lymphoblastic leukaemia, severe toxic effects led to delays in order to test modified dosing strategies, 5 Frey NV Shaw PA Hexner EO et al. Optimizing chimeric antigen receptor T-cell therapy for adults with acute lymphoblastic leukemia. J Clin Oncol. 2020; 38: 415-422 Crossref PubMed Scopus (65) Google Scholar or even complete halting of trials. 6 Cancer DiscoveryJCAR015 in ALL: a root-cause investigation. Cancer Discov. 2018; 8: 4-5 Google Scholar The toxic effects were a result of the high potency of CAR T cells, which led to remarkable cytokine elevations and permeability of the blood–brain barrier that resulted in cerebral oedema in a series of high-profile cases. 6 Cancer DiscoveryJCAR015 in ALL: a root-cause investigation. Cancer Discov. 2018; 8: 4-5 Google Scholar Toxicity seemed to be particularly lethal with more chemotherapy lymphodepletion, with CAR T cells bearing the CD28 costimulatory signalling domain (so-called sprinter CAR T cells) or in the setting of a coincident infection, which is a fairly frequent occurrence in this patient population. Children and young adults with relapsed or refractory acute lymphoblastic leukaemia seemed to tolerate these cytokine elevations much better than adults, 7 Grupp SA Kalos M Barrett D et al. Chimeric antigen receptor-modified T cells for acute lymphoid leukemia. N Engl J Med. 2013; 368: 1509-1518 Crossref PubMed Scopus (2268) Google Scholar and the first pivotal study and approval from the US Food and Drug Administration (FDA) were secured in this population with a CAR T-cell product (tisagenlecleucel) bearing the 4-1BB costimulatory domain (so-called marathoner CAR T cells). 8 Maude SL Laetsch TW Buechner J et al. Tisagenlecleucel in children and young adults with B-cell lymphoblastic leukemia. N Engl J Med. 2018; 378: 439-448 Crossref PubMed Scopus (1950) Google Scholar The FDA has since approved both CD28-bearing and 4-1BB-bearing CAR T cells targeting the CD19 antigen for adults with large-cell lymphoma (CD28-bearing: axicabtagene cilolecuel; 4-1BB-bearing: tisagenlecleucel and lisocabtagene maraleucel), mantle cell lymphoma (CD28-bearing: brexucabtagene autoleucel), and follicular lymphoma (CD28-bearing: axicabtagene cilolecuel). KTE-X19 for relapsed or refractory adult B-cell acute lymphoblastic leukaemia: phase 2 results of the single-arm, open-label, multicentre ZUMA-3 studyKTE-X19 showed a high rate of complete remission or complete remission with incomplete haematological recovery in adult patients with relapsed or refractory B-precursor acute lymphoblastic leukaemia, with the median overall survival not reached in responding patients, and a manageable safety profile. These findings indicate that KTE-X19 has the potential to confer long-term clinical benefit to these patients. Full-Text PDF

Indirect Treatment Comparison of Liso-Cel vs. Salvage Chemotherapy in Diffuse Large B-Cell Lymphoma: TRANSCEND vs. SCHOLAR-1.

Most patients with relapsed/refractory (R/R) diffuse large B-cell lymphoma (DLBCL) have exhausted their treatment options and are deemed palliative. CD19-directed chimeric antigen receptor (CAR) T-cell therapy has recently been introduced as a new option for these patients. Lisocabtagene maraleucel (liso-cel) is an investigational CAR T-cell therapy that has shown promising activity in this setting. We used an unanchored matching-adjusted indirect comparison (MAIC) methodology to compare liso-cel, using individual patient-level data from the TRANSCEND NHL 001 (TRANSCEND; NCT02631044) trial, to salvage chemotherapy, using summary-level data from the SCHOLAR-1 study, for the treatment of patients with R/R LBCL. Standardized mean differences were used to evaluate imbalances between the TRANSCEND and SCHOLAR-1 studies. MAIC was conducted to determine the relative efficacy of liso-cel vs. salvage chemotherapy with regard to overall survival, complete response rate, and objective response rate. For all efficacy outcomes assessed, comparisons of clinical factors before MAIC showed that five of seven baseline characteristics were similar between the TRANSCEND and SCHOLAR-1 studies; however, age and R/R to last therapy status differed between studies, thus requiring matching and adjusting to ensure the validity of this analysis. The base case analyses demonstrated a significantly lower risk of mortality (hazard ratio, 0.5; 95% confidence interval [CI] 0.4–0.6; p < 0.001) with significantly higher rates of complete response (odds ratio, 12.9; 95% CI 8.0–20.7) and objective response (odds ratio, 7.0; 95% CI 4.6–10.5) for patients treated with liso-cel than patients treated with salvage chemotherapy. MAIC comparisons demonstrated favorable efficacy for liso-cel compared with salvage chemotherapy in the treatment of patients with R/R LBCL.Trial Registration ClinicalTrials.gov identifier: NCT02631044.

Obese microenvironments attenuate the efficacy of endogenous and CD19-directed CAR T-cells

Abstract Background: Hematological malignancies represent the largest class of cancers in pediatric patients. Despite successes in treating primary diseases, patients with relapsed B-cell acute lymphoblastic leukemia (B-ALL) and diffuse large B-cell lymphoma (DLBCL) have significantly lower survival outcomes. This has led to the use of immunotherapies, notably chimeric antigen receptor (CAR) T-cells, to treat relapse. Unfortunately, only 50% respond to CAR-T therapy, with relapse common in less than a year. Objective: Given that obesity is associated with poorer survival outcomes in pediatric patients with B-cell malignancies and promotes a loss of immune homeostasis, we hypothesize that obesity compromises the function of endogenous and engineered T-cells in B-cell malignancies. Results: Using in vitro models of adiposity and diet-induced obesity mouse models to study the impact of obesity on primary T-cell function, we observe defects in proliferation, cytokine production, and the upregulation of cytolytic mediators when cultured in adipocyte but not in bone marrow cell or unconditioned media. The introduction of CD19-direct CARs did not overcome adipocyte-induced defects in T-cell function, which resulted in increased PD-1 surface expression, compromised cytokine production, and defective killing of human CD19-expressing B-ALL cells. Interestingly, human B-ALL cells cultured in adipocyte-secreted factors downregulated CD19, suggesting that adipocytes promote B-ALL pathogenesis by compromising T-cell function and reducing the surface expression of antigens on target cells. Conclusion: Our studies are the first to demonstrate the inhibitory impact of the adipocyte secretome on CAR T-cell function in models of B-ALL.

Outcomes for Australian children with relapsed/refractory acute lymphoblastic leukaemia treated with blinatumomab.

We report on the Australian experience of blinatumomab for treatment of 24 children with relapsed/refractory precursor B-cell acute lymphoblastic leukaemia (B-ALL) and high-risk genetics, resulting in a minimal residual disease (MRD) response rate of 58%, 2-year progression-free survival (PFS) of 39% and 2-year overall survival of 63%. In total, 83% (n=20/24) proceeded to haematopoietic stem cell transplant, directly after blinatumomab (n=12) or following additional salvage therapy (n=8). Four patients successfully received CD19-directed chimeric antigen receptor T-cell therapy despite prior blinatumomab exposure. Inferior 2-year PFS was associated with MRD positivity (20%, n=15) and in KMT2A-rearranged infants (15%, n=9). Our findings highlight that not all children with relapsed/refractory B-ALL respond to blinatumomab and factors such as blast genotype may affect prognosis.

Selecting the Optimal CAR-T for the Treatment of B-Cell Malignancies.

Chimeric antigen receptor T-cell (CAR-T) therapy is a form of adoptive cellular therapy that has revolutionized the treatment landscape in hematologic malignancies, especially B-cell lymphomas. In this review, we will discuss some of the landmark data behind these therapies and then lay out our approach to utilizing this new therapy. CD19-directed CAR-Ts are the most common type currently used in treatment of relapsed B-cell lymphoid neoplasms. There are currently three FDA-approved products: axicabtagene ciluecel and tisagenlecleucel for the treatment of relapsed/refractory large B-cell lymphoma and pediatric B-cell acute lymphocytic leukemia (tisagenlecleucel only) and brexucabtagene autoleucel for the treatment of relapsed/refractory mantle cell lymphoma. These therapies are associated with distinctive acute toxicities such as cytokine release syndrome and neurotoxicity and chronic toxicities such as cytopenias and hypogammaglobulinemia. CAR-T therapy provides significant potential in the treatment of relapsed B-cell lymphomas despite current limitations. Several novel CAR cell designs are currently being studied in clinical trials which include tandem CAR-Ts, allogeneic CAR-Ts, and CAR-NK cells.

Toxicity and effectiveness of CD19 CAR T therapy in children with high-burden central nervous system refractory B-ALL.

Although recent clinical trials have demonstrated the efficacy of CD19-directed chimeric antigen receptor (CAR) T-cell therapy for refractory or relapsed B acute lymphoblastic leukemia (r/r B-ALL), most trials exclude patients with high-burden CNS leukemia (CNSL) to avoid the risk of severe neurotoxicity. There were only sparse cases describing the effect of CAR T cells on low-burden CNSL, and the safety and effectiveness of CAR T cells in high-burden CNSL remains unknown. Here, we retrospectively analyzed the results of CD19 CAR T-cell therapy in 12 pediatric patients that had low (Blasts < 20/μL in CSF) or high-burdens (Blasts or intracranial solid mass) of CNS B-ALL, that are enrolled in three clinical trials and one pilot study at Beijing Boren Hospital RESULTS: Eleven patients (91.7%) achieved complete remission (CR) on day 30, and one patient got CR on day 90 after infusion. Most patient experienced mild cytokine-release syndrome. However, of the five patients who retained > 5/μL blasts in CSF or a solid mass before CAR T-cell expansion, four developed severe (grade 3-4) neurotoxicity featured by persistent cerebral edema and seizure, and they fully recovered after intensive managements. Sustained remission was achieved in 9 of the 12 patients, resulted in a 6-month leukemia-free survival rate of 81.8% (95% CI 59.0-100). Only one patient has CNS relapse again. Our study demonstrates that CAR T cells are effective in clearing both low- and high-burden CNSL, but a high CNSL burden before CAR T-cell expansion may cause severe neurotoxicity requiring intense intervention.

Incidence and Management of Effusions Before and After CD19-Directed Chimeric Antigen Receptor (CAR) T Cell Therapy in Large B Cell Lymphoma

In patients with lymphoma, third-space fluid accumulations may develop or worsen during cytokine release syndrome (CRS) associated with chimeric antigen receptor (CAR) T cell therapy. Pre-existing symptomatic pleural effusions were excluded by the ZUMA-1 trial of axicabtagene ciloleucel for large B cell lymphoma (LBCL) and variants. The incidence and management of effusions during CAR T cell therapy for LBCL are unknown. We performed a single-center retrospective study evaluating 148 patients receiving CD19-directed CAR T cell therapy for LBCL between May 2015 and September 2019. We retrospectively identified patients who had radiographic pleural, pericardial, or peritoneal effusions that were present prior to the time of CAR T infusion (pre-CAR T) or that newly developed during the first 30 days after CAR T-cell infusion (post-CAR T). Of 148 patients, 19 patients had a pre-CAR T effusion, 17 patients without pre-existing effusion developed a new infusion after CAR T, and 112 patients had no effusions. Comparing pre-CAR T effusions to new effusions post-CAR T, pre-CAR T effusions were more often malignant (84% versus 12%), persistent beyond 30 days (95% versus 18%), and required interventional drainage after CAR T infusion (79% versus 0%). Compared to patients with no effusion, patients with pre-CAR T therapy effusions had a higher frequency of high-risk baseline characteristics, such as bulky disease and high International Prognostic Index. Similarly, patients with pre-CAR T therapy effusions had a higher rate of toxicity with grade 3 or higher CRS occurring in 32% of patients. On multivariate analysis adjusting for age, Eastern Cooperative Oncology Group status, bulky disease, albumin, and lactate dehydrogenase, a pre-CAR T therapy effusion was associated with reduced overall survival (hazard ratio, 2.34; 95% confidence interval, 1.09 to 5.03; P = .03). Moreover, there was higher non-relapse mortality (11% versus 1%; P = .005). Post-CAR T effusions were not associated with significant difference in survival. Effusions commonly complicate CAR T cell therapy for lymphoma. Malignant effusions that occur prior to CAR T therapy are frequently persistent and require therapeutic intervention, and patients have a higher rate of toxicity and death. Effusions that newly occur after CAR T therapy can generally be managed medically and tend not to persist.

Hypogammaglobulinemia and Infection Risk in Chronic Lymphocytic Leukemia (CLL) Patients Treated with CD19-Directed Chimeric Antigen Receptor T (CAR-T) Cells

Hypogammaglobulinemia and Infection Risk in Chronic Lymphocytic Leukemia (CLL) Patients Treated with CD19-Directed Chimeric Antigen Receptor T (CAR-T) Cells

Outcomes of Patients Requiring ICU Admission after CD19 Directed CAR T-Cells

Introduction:Chimeric antigen receptor (CAR) T-cells are engineered T-cells that target specific antigens on tumor cell surfaces. CD19 directed CAR T-cells have demonstrated efficacy in B-cell lymphomas and B-cell acute lymphoblastic leukemia (B-ALL); however, patients are at risk for life-threatening complications including cytokine release syndrome (CRS) and immune effector cell-associated neurotoxicity syndrome (ICANS). Grade 3 ICANS and higher have been reported in 12-28% and Grade 3 CRS and higher in 1-23% in pivotal studies for B-cell lymphoma.1 The majority, if not all, patients with Grade 3 ICANS and CRS require intensive care unit (ICU) admission. The long-term outcomes of patients requiring ICU admission after CD19 directed CAR T-cells are unknown. Methods:Clinical data were retrospectively reviewed from consecutive patients with relapsed or refractory B-cell lymphomas and B-ALL treated with axicabtagene ciloleucel or tisagenlecleucel at a single institution from January 1, 2016 to July 1, 2020. Diagnosis of CRS and ICANS was based on the American Society for Transplantation and Cellular Therapy consensus grading.2 Demographics, medical co-morbidities, therapeutic interventions, relapse rate, and all-cause mortality were assessed. Results:Thirty-seven patients received CAR T-cells. Sixty-seven percent (n=25) of patients were male with a median age of 55 years (range 23 - 77). Eighty-nine percent of patients had large B cell lymphoma. Patients received a median of 3 prior therapies (range 1 - 6). The median IPI and ECOG scores at time of CAR T-cells administration were 3 and 1, respectively. Forty-three percent (n=16) of patients required ICU admission. The median length of ICU stay was 3.5 days (range 1 - 18). The median CRS and ICANS grades in patients requiring ICU admission were 2 and 3, compared to 2 and 0 in patients not requiring ICU admission, respectively. Thirty-one percent of ICU admitted patients had CRS grade 3 or above, and 61% had ICANS grade 3 or above. All 4 patients with B-ALL experienced grade 3 or above CRS and required ICU admission. Only 1 of the 37 patients (2.7%) patients died from CRS. Fifty-six percent of ICU patients experienced disease progression during follow-up, compared to 33% of non-ICU patients (OR 2.50, p = 0.20, 95% CI 0.55-12.11). Over a median follow up of 399 days, 56% of ICU patients died compared to 14% of non-ICU patients (OR 7.23, p = 0.01, 95% CI 1.32-54.27). The majority of deaths (58%) were due to disease progression. Conclusions:A significant number of patients who receive CD-19 direct CAR T-cells require ICU admission. Patients requiring ICU admission after CAR T-cell have a worse outcome and overall survival, compared to non-ICU patients. The mortality rate of ICU admitted patients is primarily driven by death from disease. Disclosures Tzachanis: MS:Research Funding;EUSA Pharma:Consultancy;Fate:Research Funding;Genetech:Research Funding;Gilead Sciences:Consultancy, Research Funding, Speakers Bureau;Incyte:Research Funding;Jazz Pharmaceuticals:Consultancy;Kyowa Kirin:Consultancy;Magenta:Consultancy;Takeda:Consultancy, Speakers Bureau.Goodman:Seattle Genetics:Consultancy;EUSA Pharma:Consultancy.

Obesity Attenuates T-Cell Function Which Impacts the Efficacy of T-Cell Based Immunotherapies in Acute Lymphoblastic Leukemia

The incidence of obesity continues to rise with over 50% of the world's population predicted to be overweight/obese by the year 2030. The global health impact of this trend is concerning given that obesity is a risk factor for developing cancers of varying etiologies. Alarmingly, the survival outcomes for obese patients with cancer are lower than those observed in lean patients. Obesity is characterized by the accumulation of adipocytes which alters drug dynamics and impacts the function of cancer and immune cells in the tumor microenvironment. Obesity-induced immune defects are troubling given the increasing use of immunotherapy in the treatment of malignancies. Here we show that adipocyte-secreted factors upregulate immunosuppressive mechanisms on human B-cell acute lymphoblastic leukemia (B-ALL) cells, attenuate the function of endogenous T-cells, and compromise the efficacy of T-cell based immunotherapies. To study the impact of adiposity on T-cell function, CD4+ and CD8+ T-cells were purified from the spleens of C57BL/6 mice and activated with PMA/Ionomycin for 72 hours in unconditioned media (UCM), bone marrow stromal-cell conditioned media (SCM), and adipocyte-conditioned media (ACM) followed by flow cytometry analysis for surface marker expression, cytokine production, and the induction of cytolytic mediators. Interestingly, T-cells activated in ACM, but not UCM or SCM, showed an attenuated phenotype highlighted by decreased CD44 and PD-1 expression, diminished cytokine production (IFN-γ/TNF-α) and reduced induction of cytolytic mediators (granzyme B/perforin). These observations were also true in obese, relative to lean, patients with B-ALL where we found that T-cells purified from the peripheral blood mononuclear cells (PBMCs) failed to produce significant levels of TNF-α when stimulated with PMA/Ionomycin. In all, these results demonstrate that adipocyte-secreted factors directly compromise the function of endogenous T-cells, which phenocopies T-cell defects observed in obese relative to lean pediatric patients with B-ALL. We next assessed the impact of adiposity on malignant cells by culturing human B-ALL cell lines in the conditioned mediums described above and performed flow cytometric analysis to assess their surface expression of the B-cell lineage antigen CD19 and proteins that modulate immunity. In addition to being a marker for B-cells, CD19 is the primary target of the T-cell based immunotherapies Blinatumomab and CAR T-cells directed against B-ALL cells. Surprisingly, when human B-ALL cells were co-cultured with adipocytes, every cell line tested (n=6) exhibited lower surface CD19 expression with 5 out 6 reaching statistical significance. Furthermore, adipocyte-secreted factors alone were sufficient to reduce CD19 surface levels on B-ALL cells in 2 of the 6 cell lines tested. Human B-ALL cells cultured in ACM, but not UCM or ACM, also upregulated their surface expression of the immunoinhibitory proteins HVEM, PD-L1, and PD-L2. These results demonstrate that adipocytes directly induce the downregulation of CD19 on human B-ALLs and increase their immune evasive capacity. Given these observations, we hypothesized that adipocyte-secreted factors would compromise T-cell-based immunotherapies targeting CD19-expressing B-ALL cells. To this end, primary human T-cells were engineered to express a CD19-directed chimeric antigen receptor (CAR). CAR T-cells and human B-ALL cells were separately pre-treated for 24 hours in UCM, SCM or ACM followed by co-culture for cytolytic analysis using Annexin-V/PI staining. Adipocyte-secreted factors significantly inhibited CAR T-cell mediated killing of CD19-expressing B-ALL cells at 4 hours. In addition to CAR T-cells, we tested the leukemia killing efficacy of the bispecific T-cell engager, Blinatumomab. After 3 days of culture, we found that Blinatumomab significantly increased the killing capacity of endogenous T-cells with 60-80% of B-ALL cells being killed after 3 days of culture in UCM and SCM. In contrast, we found that ACM significantly compromised the efficacy Blinatumomab with only 30% of B-ALL cells being killed over 3 days when co-cultured with human T-cells. Our pre-clinical data highlights the negative impact of an adipose-rich microenvironment on T-cell function and B-ALL immunogenicity, which subsequently compromises the efficacy of multiple classes of immunotherapies targeting CD19. Disclosures No relevant conflicts of interest to declare.