[The proportion of CD19+CD25+ Bregs in peripheral blood and the expression of PD-1 and PD-L1 on cell surface in patients with systemic lupus erythematosus and their correlation with clinical indicators].

Objective To investigate the expression and clinical significance of PD-1 and its ligand PD-L1 in peripheral blood CD19+CD25+ regulatory B cells (Bregs) in patients with systemic lupus erythematosus (SLE). Methods Peripheral blood samples were collected from 50 patients and 41 healthy controls (HCs). The proportion of CD19+CD25+Bregs in peripheral blood as well as the expression of PD-1+B and PD-L1+B cells on CD19+CD25+/-B cells, were detected by flow cytometry. At the same time, clinical information, such as clinical manifestations and laboratory indexes, was collected from patients. CD4+T cells and CD19+B cells were isolated by immunomagnetic beads and co-cultured in vitro to detect the differentiation of Bregs. Results The proportion of CD19+CD25+Bregs in the peripheral blood of SLE patients was lower than that in HC, while the expression of PD-1 and PD-L1 on Bregs was higher than that in HCs. SLE patients with pleural effusion, arthritis, and elevated CRP had a higher frequency of Bregs compared to the corresponding negative group. SLE patients with decreased immunoglobulin M (IgM) and positive anti-ribonuclear protein (RNP) antibodies had a lower frequency of Bregs compared to the corresponding negative group. SLE patients with infection, fever, arthritis, and elevated immunoglobulin A (IgA) had a higher frequency of CD19+CD25+PD-1+ cells compared to the corresponding negative group. SLE patients with infection, fever, and elevated IgA had a higher frequency of CD19+CD25+PD-L1+ cells compared to the corresponding negative group. And activated CD4+T cells were beneficial to the expression of CD25 on CD19+B cells. Conclusion The peripheral blood CD19+CD25+ Bregs are decreased in SLE patients, while the expression of PD-1 and PD-L1 on cell surface is increased, which is correlated with clinical manifestations and laboratory parameters. Activation of CD4+T cells promotes the differentiation of Bregs.

Bendamustine lymphodepletion is a well-tolerated alternative to fludarabine and cyclophosphamide lymphodepletion for axicabtagene ciloleucel therapy for aggressive B-cell lymphoma.

Fludarabine/cyclophosphamide (Flu/Cy) is established for lymphodepletion (LD) prior to standard-of-care CAR T-cell therapy for lymphoma. There is ongoing need to test alternative LD regimens to preserve efficacy, improve safety, and address challenges including the recent national fludarabine shortage. We retrospectively evaluated outcomes among patients with relapsed/refractory aggressive B-cell lymphoma who received bendamustine (n = 27) or Flu/Cy (n = 42) LD before axicabtagene ciloleucel (axi-cel) at our institution. The median change in absolute lymphocyte count from pre-LD to time of axi-cel infusion was -0.6×109 /L in bendamustine cohort and -0.7×109 /L in Flu/Cy cohort. The best overall response/complete response rates were 77.8% (95% CI: 57.7%-91.4%)/48.1% (95% CI: 28.7%-68.1%) among bendamustine cohort and 81.0% (95% CI: 65.9%-91.4%)/50.0% (95% CI: 34.2%-65.8%) among Flu/Cy cohort. Six-month progression-free survival were 43.8% (95% CI: 24.7%-61.3%) and 55.6% (95% CI: 39.0%-69.3%) in bendamustine and Flu/Cy cohorts, while 6-month overall survival were 81.5% (95% CI: 61.1%-91.8%) and 90.4% (95% CI: 76.4%-96.3%), respectively. Relative to Flu/Cy-treated patients, bendamustine-treated patients did not show an increase in hazards associated with experiencing progression/relapse/death (aHR:1.4 [95% CI: 0.7-2.8]; p = .32) or death (aHR:1.6 [95% CI: 0.5-5.6]; p = .46), after adjusting for baseline number of prior therapies and refractory disease. Any grade/grade ≥3 CRS were observed in 89%/3.7% and 86%/4.8% among bendamustine and Flu/Cy cohorts, while any grade ICANS/grade ≥3 ICANS were observed in 30%/19% and 55%/31% respectively. While more Flu/Cy-treated patients experienced grade ≥3 neutropenia compared with bendamustine-treated patients (100% vs. 68%), grade ≥3 infectious complications were comparable (24% vs. 19% respectively). More patients received bendamustine LD and axi-cel as outpatient than Flu/Cy cohort, without increased toxicities and with shorter median inpatient stays. In conclusion, we observed comparable efficacy and lower any grade ICANS among patients receiving bendamustine relative to Flu/Cy LD, followed by axi-cel.

The nutritional impact of CD19-targeted CAR-T therapy versus BEAM chemotherapy for adult patients with lymphoma.

BACKGROUND: Chimeric antigen receptor T (CAR-T) cell therapy is a novel therapy demonstrating durable remissions in patients with refractory or relapsing non-Hodgkin's B-cell lymphoma. Maintaining a patient's nutritional status has been demonstrated to improve outcomes in cancer treatment. However, no studies have investigated how CAR-T therapy affects nutritional status, nor compared its impact with other cancer treatments for this patient group. The primary aim of the present study was to investigate the effect of CAR-T therapy on the prevalence of nutrition impact symptoms (NIS) and nutritional status within 30 days post-treatment of patients with lymphoma compared to a conditioning regimen for autologous haematopoetic stem cell transplant (carmustine/BCNU, Etoposide, cytarabine/Ara-C, Melphalan [BEAM] auto-haematopoetic stem cell transplant [HSCT]). METHODS: Clinical notes of patients with lymphoma who underwent either CAR-T therapy or BEAM auto-HSCT between 2018 and 2021 were reviewed. Data extracted included body weight measurements and NIS, including decreased appetite, nausea, vomiting, diarrhoea, constipation, mucositis, cytokine release syndrome (CRS) and neurotoxicity at baseline and 30 ± 7 days post-treatment. RESULTS: In total, 129 adults with lymphoma (n = 88 CAR-T vs. n = 41 BEAM) were included. Nutritional status was assessed in both groups at baseline prior to treatment. Mean absolute weight change was significantly different between groups (3.05 kg in CAR-T, -5.9 kg in BEAM, p ≤ 0.001). This was also significant when weight loss was categorised into percentage weight loss (p = 0.01). CAR-T patients experienced a significantly lower prevalence of decreased appetite (52.3% vs. 97.6%) nausea (25% vs. 78%,) vomiting (10.2% vs. 53.7%), diarrhoea (43.2% vs. 96.7%) and mucositis (5.7% vs. 75.6%) combined across all levels of severity compared to BEAM chemotherapy (all p ≤ 0.01). CRS and neurotoxicity, which are specific side effects of CAR-T therapy, were moderately positively associated with weight loss. CONCLUSIONS: Weight loss, percentage weight loss and NIS were significantly reduced in CAR-T compared to BEAM treatment. However, patients who experienced neurotoxicity during treatment did have significant weight loss.

Influence of Adipose Tissue Distribution, Sarcopenia, and Nutritional Status on Clinical Outcomes After CD19 CAR T-cell Therapy.

Although CD19-directed chimeric antigen receptor T-cell therapy (CD19.CAR-T) has proven clinical efficacy for multiple refractory B-cell malignancies, over 50% of patients ultimately relapse. Recent evidence has underlined the critical role of the host in determining treatment responses. In this retrospective observational study of 106 patients with relapsed/refractory large B-cell lymphoma receiving standard-of-care CD19.CAR-T, we analyzed the impact of immunometabolic host features and detailed body composition measurements on post-CAR T clinical outcomes. We extracted muscle and adipose tissue distributions from prelymphodepletion CT images and assessed laboratory-based immuno-nutritional scores. Early responders displayed increased total abdominal adipose tissue deposits (TAT: 336 mm3 vs. 266 mm3, P = 0.008) and favorable immuno-nutritional scores compared to nonresponding patients. On univariate Cox regression analysis, visceral fat distribution, sarcopenia, and nutritional indices significantly impacted both progression-free (PFS) and overall survival (OS). Patients with a low skeletal muscle index (SMI; e.g.<34.5), a sarcopenia indicator, exhibited poor clinical outcomes (mOS 3.0 months vs. 17.6 months, log-rank P = 0.0026). Prognostically adverse immuno-nutritional scores were linked to inferior survival [low PNI: HROS, 6.31; 95% confidence interval (CI), 3.35-11.90; P < 0.001]. In a multivariable analysis adjusting for baseline Eastern Cooperative Oncology Group performance status, C-reactive protein, and lactate dehydrogenase, increased TAT was independently associated with improved clinical outcomes (adjusted HROS, 0.27; 95% CI, 0.08-0.90; P = 0.03). We noted particularly favorable treatment outcomes in patients with both increased abdominal fat and muscle mass (TAThigh/SMIhigh: 1-year PFS 50%, 1-year OS 83%). These real-world data provide evidence for a role of body composition and immuno-nutritional status in the context of CD19.CAR-T and suggest that the obesity paradox may extend to modern T cell-based immunotherapies. See related Spotlight by Nawas and Scordo, p. 704.

Costs, effectiveness, and safety associated with Chimeric Antigen Receptor (CAR) T-cell therapy: Results from a comprehensive cancer center.

Real world effectiveness, toxicity and costs analyses from chimeric antigen receptor (CAR)-T cell therapy are of utmost relevance to determine whether and how to offer patients highly personalized immunotherapy. In this study, we aimed at describing CAR T-cells effectiveness, safety and costs in a Portuguese Comprehensive Cancer Center. We performed a retrospective descriptive study of adult patients with relapsed/refractory diffuse large B-cell lymphoma (DLBCL), primary mediastinal B-cell lymphoma and transformed follicular lymphoma referred to CAR T-cell therapy, between May 2019 and February 2021. Rates of treatment response, toxicity and survival (Kaplan-Meier method) were analyzed by intention-to-treat. Direct medical costs stratified by inpatient-care, outpatient-care, and diagnostic-therapeutic procedures (DTP) were derived based on resources used and their respective unit costs. In twenty patients (median age 49.5y; 55%male; 70%DLBCL; 50% with primary refractory disease), best overall and complete response rates were 65.0% and 45.0%, respectively. Median overall (OS) and progression-free survivals were 9.2 and 7.3 months; 12-month OS rate was 42.6% (95%CI:23.2-78.3). Grade≥3 cytokine release syndrome and neurotoxicity occurred in 5.6% and 11.1% of patients, respectively. CAR T-cell therapy expenditure, including adverse events costs, was 7 176 196€, or 286 238€ when excluding drug cost. Median cost for treated patient was 355 165€ with CAR T-cell drug cost accounting for 97.0% of the overall expense. Excluding CAR T-cell acquisition cost, inpatient-care and DTP accounted for 57% and 38% of total cost/patient, respectively. Our findings highlight the heavy economic burden of CAR T-cell therapy driven by drug acquisition costs.

Hypophosphatemia Due to Increased Effector Cell Metabolic Activity Is Associated with Neurotoxicity Symptoms in CD19-Targeted CAR T-cell Therapy.

A major complication of chimeric antigen receptor (CAR) T-cell therapy is immune effector cell-associated neurotoxicity syndrome (ICANS), which presents as aphasia, confusion, weakness, somnolence, seizures, and coma. This is similar to the neurologic manifestations of hypophosphatemia, which can result from sudden increases in metabolic demand for phosphorylated intermediates (e.g., refeeding syndrome and sepsis). Given these similarities, we investigated whether CAR T-cell effector metabolic activity is associated with increased extracellular phosphate consumption and a possible association between hypophosphatemia and ICANS. In vitro 4-1BB and CD28 CD19-targeted CAR T-cell effector activity was found to be associated with increased consumption of media phosphorus, which was temporally associated with increased single-cell effector secretomic activity and increased phosphorus-dependent metabolic demand of the CAR T cells. A clinical cohort of 77 patients treated with CD19-targeted CAR T-cell therapy demonstrated a significant anticorrelation between serum phosphorus and ICANS incidence and severity, with earlier onset of hypophosphatemia after CAR T-cell infusion more likely to result in neurotoxicity. These results imply phosphorous level monitoring could alert to the development of ICANS in clinical scenarios. See related Spotlight by Tobin et al., p. 1422.

TPEN selectively eliminates lymphoblastic B cells from bone marrow pediatric acute lymphoblastic leukemia patients.

B-cell acute lymphoblastic leukemia (B-ALL) is a hematologic disorder characterized by the abnormal proliferation and accumulation of immature B-lymphoblasts arrested at various stages of differentiation. Despite advances in treatment, a significant percentage of pediatric patients with precursor B-ALL still relapse. Therefore, alternative therapies are needed to improve the cure rates for pediatric patients. TPEN (N, N, N', N'-tetrakis(2-pyridylmethyl)-ethylenediamine) is a pro-oxidant agent capable of selectively inducing apoptosis in leukemia cell lines. Consequently, it has been suggested that TPEN could be a potential agent for oxidative therapy. However, it is not yet known whether TPEN can selectively destroy leukemia cells in a more disease-like model, for example, the bloodstream and bone marrow (BM), ex vivo. This investigation is an extension of a previous study that dealt with the effect of TPEN on ex vivo isolated/purified refractory B-ALL cells. Here, we evaluated the effect of TPEN on whole BM from nonleukemic patients (control) or pediatric patients diagnosed with de novo B-ALL or refractory B-ALL cells by analyzing the hematopoietic cell lineage marker CD34/CD19. Although TPEN was innocuous to nonleukemic BM (n = 3), we found that TPEN significantly induced apoptosis in de novo (n = 5) and refractory B-ALL (n = 6) leukemic cell populations. Moreover, TPEN significantly increased the counts of cells positive for the oxidation of the stress sensor protein DJ-1, a sign of the formation of H2O2, and significantly increased the counts of cells positive for the pro-apoptotic proteins TP53, PUMA, and CASPASE-3 (CASP-3), indicative of apoptosis, in B-ALL cells. We demonstrate that TPEN selectively eliminates B-ALL cells (CD34 + /CD19 +) but no other cell populations in BM (CD34 + /CD19-; CD34-/CD19 + ; CD34-/CD19-) independent of age, diagnosis status (de novo or refractory), sex, karyotype, or immunophenotype. Understanding TPEN-induced cell death in leukemia cells provides insight into more effective therapeutic oxidation-inducing anticancer agents.

Anti-CD19 monoclonal antibodies for the treatment of relapsed or refractory B-cell malignancies: a narrative review with focus on diffuse large B-cell lymphoma.

PURPOSE: CD19 is a cell surface protein that is found on both healthy and malignant B cells. Accordingly, it has become an important target for novel treatments for non-Hodgkin lymphomas and B-cell leukaemia. Three anti-CD19 monoclonal antibodies with distinct mechanisms of action have been developed for the treatment of B-cell malignancies. METHODS: We reviewed the preclinical and clinical data on the development of the newly approved anti-CD19 monoclonal antibodies blinatumomab, tafasitamab and loncastuximab tesirine, and consider their place in the treatment of relapsed or refractory B-cell malignancies. RESULTS: Blinatumomab is a bispecific T-cell engager that binds to both CD19 on B cells and CD3 on T cells, facilitating antibody-dependent cytotoxicity. Blinatumomab significantly prolongs overall survival in patients with relapsed or refractory B-cell acute lymphoblastic leukaemia, although cytokine release syndrome and severe neurotoxicity may necessitate discontinuation. Tafasitamab, which has modified anti-CD19 Fab and Fc regions, has significantly enhanced affinity for both CD19 and effector cell receptors compared with unmodified anti-CD19. In L-MIND, tafasitamab plus lenalidomide provided an overall response rate (ORR) of 57.5% in patients with relapsed or refractory diffuse large B-cell lymphoma (DLBCL) in patients non-transplant eligible. Loncastuximab tesirine is an antibody-drug conjugate that has been studied as monotherapy and in combination with ibrutinib in 3L + relapsed or refractory DLBCL. The ORR was 48.3% in a phase II trial of loncastuximab tesirine. The optimal place of anti-CD19 monoclonal antibodies in therapy has yet to be determined, but the prospect of improved outcomes for at least some patients with treatment-resistant B-cell malignancies appears likely, particularly in those with limited therapeutic options and poor prognosis.

Mucosal-associated invariant T (MAIT) cells, a new source of universal immune cells for chimeric antigen receptor (CAR)-cell therapy.

Treatment of hematological malignancies by autologous T cells expressing a chimeric antigen receptor (CAR) is a breakthrough in the field of cancer immunotherapy. As CAR-T cells are entering advanced phases of clinical development, there is a need to develop universal, ready-to-use products using immune cells from healthy donors, to reduce time to treatment, improve response rate and finally reduce the cost of production. Mucosal-associated invariant T cells (MAIT) are unconventional T cells which recognize microbial-derived riboflavin derivatives presented by the conserved MR1 molecule and are endowed with potent effector functions. Because they are not selected by classical MHC/peptide complexes and express a semi-invariant T cell receptor, MAIT cells do not mediate alloreactivity, prompting their use as a new source of universal effector cells for allogeneic CAR-T cell therapy without the need to inactivate their endogenous TCR. We produced CD19-CAR MAIT cells as proof-of-concept allowing subsequent head-to-head comparison with currently used CD19-CAR T cells. We demonstrated their anti-tumor efficacy in vitro and their capacity to engraft without mediating GVHD in preclinical immunodeficient mouse models. Universal, off-the-shelf CAR-MAIT cells could provide a suitable alternative to current autologous CAR-T cells to treat patients regardless of HLA disparity, without production delay, enabling a cost-effective manufacturing model for large-scale clinical application.

Targeting folate receptor beta on monocytes/macrophages renders rapid inflammation resolution independent of root causes.

Provoked by sterile/nonsterile insults, prolonged monocyte mobilization and uncontrolled monocyte/macrophage activation can pose imminent or impending harm to the affected organs. Curiously, folate receptor beta (FRß), with subnanomolar affinity for the vitamin folic acid (FA), is upregulated during immune activation in hematopoietic cells of the myeloid lineage. This phenomenon has inspired a strong interest in exploring FRß-directed diagnostics/therapeutics. Previously, we have reported that FA-targeted aminopterin (AMT) therapy can modulate macrophage function and effectively treat animal models of inflammation. Our current investigation of a lead compound (EC2319) leads to discovery of a highly FR-specific mechanism of action independent of the root causes against inflammatory monocytes. We further show that EC2319 suppresses interleukin-6/interleukin-1ß release by FRß+ monocytes in a triple co-culture leukemic model of cytokine release syndrome with anti-CD19 chimeric antigen receptor T cells. Because of its chemical stability and metabolically activated linker, EC2319 demonstrates favorable pharmacokinetic characteristics and cross-species translatability to support future pre-clinical and clinical development.

Expression Level of Membrane Markers CD5, CD19, and CD20 in B Cells after UV-Irradiation and Incubation in the Presence of Autologous Plasma.

The effect of UV-light (240-390 nm) in doses of 151 and 755 J/m2 on the expression of membrane markers CD5, CD19, CD20 in human peripheral blood B cells was studied by flow cytometry. In 24 h after exposure to UV light, we observed activation of processes accompanied by structural rearrangements of B-cell membranes leading to changes in the expression of receptor molecules: the content of of CD19 and CD20 increased due to activation of the synthesis of these proteins, while the content of CD5 decreased. The percentage of CD5+ cells decreased over 24 h after UV-irradiation of lymphocytes, while addition of autologous plasma to the incubation medium produced a photoprotective effect on CD5+ cells.

Donor-derived CD19 CAR-T cell therapy of relapse of CD19-positive B-ALL post allotransplant.

Safety and efficacy of allogeneic anti-CD19 chimeric antigen receptor T cells (CAR-T cells) in persons with CD19-positive B-cell acute lymphoblastic leukemia (B-ALL) relapsing after an allotransplant remain unclear. Forty-three subjects with B-ALL relapsing post allotransplant received CAR-T cells were analyzed. 34 (79%; 95% confidence interval [CI]: 66, 92%) achieved complete histological remission (CR). Cytokine release syndrome (CRS) occurred in 38 (88%; 78, 98%) and was ≥grade-3 in 7. Two subjects died from multiorgan failure and CRS. Nine subjects (21%; 8, 34%) developed ≤grade-2 immune effector cell-associated neurotoxicity syndrome (ICANS). Two subjects developed ≤grade-2 acute graft-versus-host disease (GvHD). 1-year event-free survival (EFS) and survival was 43% (25, 62%). In 32 subjects with a complete histological remission without a second transplant, 1-year cumulative incidence of relapse was 41% (25, 62%) and 1-year EFS and survival, 59% (37, 81%). Therapy of B-ALL subjects relapsing post transplant with donor-derived CAR-T cells is safe and effective but associated with a high rate of CRS. Outcomes seem comparable to those achieved with alternative therapies but data from a randomized trial are lacking.

Tracing Human IgE B Cell Antigen Receptor-Bearing Cells With a Monoclonal Anti-Human IgE Antibody That Specifically Recognizes Non-Receptor-Bound IgE.

Up to 30% of the population suffers from immunoglobulin E (IgE)-mediated allergies. Despite current stepwise gating approaches, the unambiguous identification of human IgE-producing cells by flow cytometry and immunohistology remains challenging. This is mainly due to the scarcity of these cells and the fact that IgE is not only expressed in a membrane-bound form on the surface of IgE-producing cells in form of the B cell antigen receptor (BCR), but is more frequently found on various cell types bound to the low and high affinity receptors, CD23 and FcϵRI, respectively. Here we sought to develop a sequential gating strategy for unambiguous detection of cells bearing the IgE BCR on their surface. To that aim we first tested the monoclonal anti-IgE antibody omalizumab for its ability to discriminate between IgE BCR and receptor-bound IgE using cells producing IgE or bearing IgE bound to CD23 as well as basophils exhibiting FcϵRI receptor-bound IgE. Using flow cytometry, we demonstrated that omalizumab recognized IgE producing cells with a high sensitivity of up to 1 IgE+ cell in 1000 human peripheral blood mononuclear cells (PBMCs). These results were confirmed by confocal microscopy both in cell suspensions as well as in nasal polyp tissue sections. Finally, we established a consecutive gating strategy allowing the clear identification of class-switched, allergen-specific IgE+ memory B cells and plasmablasts/plasma cells in human PBMCs. Birch pollen specific IgE+ memory B cells represented on average 0.734% of total CD19+ B cells in allergic patients after allergen exposure. Thus, we developed a new protocol for exclusive staining of non-receptor bound allergen-specific IgE+ B cell subsets in human samples.

Anti-CD19 chimeric antigen receptor T-cell therapy in acute lymphocytic leukaemia: a systematic review and meta-analysis.

BACKGROUND: Anti-CD19 chimeric antigen receptor (CAR) T-cell therapy has shown remarkable activity in patients with refractory or relapsed acute lymphocytic leukaemia. Various anti-CD19 CAR T-cell constructs have been trialled and responses vary widely among different studies. We aimed to systematically analyse the outcomes of patients with acute lymphocytic leukaemia treated with anti-CD19 CAR T cells and identify factors associated with differences in outcomes. METHODS: We did a systematic review and meta-analysis of published and unpublished clinical trials that reported data on the outcomes of adult or paediatric patients that were treated with anti-CD19 CAR T cells for relapsed or refractory B-cell acute lymphocytic leukaemia, reported between Jan 1, 2012, and April 14, 2020. Studies with two patients or fewer were excluded and summary data were extracted from the reports. The primary outcome was the number of patients who had complete remission at any time after anti-CD19 CAR T-cell infusion. This study is not registered in PROSPERO. FINDINGS: From 1160 studies, we identified 40 potentially appropriate studies, 35 (88%) of which met the eligibility criteria and were included in the final analysis (n=953 patients). The pooled complete remission was 80% (95% CI 75·5-84·8) and heterogeneity between studies was moderate (I2=56·96%). In the prespecified subgroup analyses, 195 (75% [95% CI 66·9-82·9, I2=35·22%]) of 263 patients in adult studies and 242 (81% [72·9-87·2, I2=54·45%]) of 346 patients in paediatric studies achieved complete remission, p=0·24. The pooled complete remission did not significantly differ with anti-CD19 CAR T-cell construct type or single-chain variable fragment clone, but was higher with autologous T-cell origin (727 [83%, 78·5-86·5, I2=44·34%] of 901 patients), compared with allogeneic T-cell origin (29 [55%, 30·6-79·0, I2=62·64%] of 52 patients; p=0·018). 242 (26% [95% CI 18·5-34·1]) of 854 patients developed grade 3 or worse cytokine release syndrome and 97 (12% [6·6-19·2]) of 532 developed grade 3 or worse neurotoxicity. There was no difference in the proportion of patients who achieved complete remission or who had cytokine release syndrome or neurotoxicity between different anti-CD19 CAR T-cell constructs. The risk of bias was assessed as low in 17 studies and moderate in 18 studies. INTERPRETATION: The high response rates after anti-CD19 CAR T-cell therapy can be used to guide the use of therapy in patients with relapsed or refractory acute lymphocytic leukaemia. Comparison studies are required to further determine differences in efficacy between different anti-CD19 CAR T-cell constructs in the setting of relapsed or refractory acute lymphocytic leukaemia. FUNDING: National Cancer Institute, National Comprehensive Cancer Network, Mayo Clinic K2R Research Pipeline, and Mayo Clinic Center for Individualized Medicine.

T Cell-Activating Bispecific Antibodies in Cancer Therapy.

Effector lymphocytes are multifunctional cells of the immune system that promote cytolysis of pathogen-infected cells and nascent tumors. Tumors must learn to evade effectors and employ a wide variety of mechanisms to do so. Bispecific Abs (BsAbs) are an emerging cancer immunotherapy approach seeking to re-engage either T effectors or NK cells with malignant cells. Possessing specificity for effector cells on one end and a tumor Ag on the other, these molecules work by attracting effectors to the target cell to build an immunologic synapse and induce tumor cell killing. The BsAb blinatumomab, for example, has specificity for the T cell-activating cell surface protein CD3 and the B cell Ag CD19. The only BsAb with regulatory approval currently, blinatumomab is used in the treatment of relapsed or refractory B cell acute lymphoblastic leukemia. Many additional BsAbs are in preclinical development, however, targeting many different tumor types. The variety of potential effector cells and cancer Ags, along with potential combination therapies, make BsAbs an active area of drug development. In this review, we discuss cancer recognition by the immune system and structural and mechanistic aspects of BsAbs. We summarize key steps in preclinical development and subsequent translation to medical practice. Future directions for BsAbs include combinations with a wide variety of both immunologic and nonimmunologic therapies. Defining their optimum clinical use is at early stages.

Preclinical activity of the antibody-drug conjugate denintuzumab mafodotin (SGN-CD19A) against pediatric acute lymphoblastic leukemia xenografts.

BACKGROUND: Denintuzumab mafodotin (SGN-CD19A) is a CD19-targeting antibody-drug conjugate, comprising a monoclonal antibody conjugated to the potent cytotoxin monomethyl auristatin F. Since denintuzumab mafodotin has previously shown activity against B-cell malignancies in early-stage clinical trials, it was of interest to test it against the Pediatric Preclinical Testing Program preclinical models of CD19+ pediatric acute lymphoblastic leukemia (ALL). PROCEDURES: Denintuzumab mafodotin was evaluated against eight B-cell lineage ALL patient-derived xenografts (PDXs), representing B-cell precursor ALL, Ph-like ALL, and mixed-lineage leukemia rearranged infant ALL. Denintuzumab mafodotin was administered weekly for 3 weeks at 3 mg/kg. It was also tested in combination with an induction-type chemotherapy regimen of vincristine, dexamethasone, and l-asparaginase (VXL) against three PDXs. The relationship between cell surface and gene expression of CD19 and drug activity was also assessed. RESULTS: Denintuzumab mafodotin significantly delayed the progression of seven of eight PDXs tested and achieved objective responses in five of eight. There was no apparent subtype specificity of denintuzumab mafodotin activity. No correlations were observed between CD19 mRNA or cell surface expression and denintuzumab mafodotin activity, perhaps due to small sample size, and denintuzumab mafodotin treatment did not select for reduced CD19 expression. Combining denintuzumab mafodotin with VXL achieved therapeutic enhancement compared to either treatment alone. CONCLUSIONS: Denintuzumab mafodotin showed single-agent activity against selected B-lineage ALL PDXs, although leukemia growth was evident in most models at 28 days from treatment initiation. This level of activity for denintuzumab mafodotin is consistent with that observed in adults with ALL.

Safety and tolerability of conditioning chemotherapy followed by CD19-targeted CAR T cells for relapsed/refractory CLL.

BACKGROUND: Subgroups of patients with relapsed or refractory (R/R) chronic lymphocytic leukemia (CLL) exhibit suboptimal outcomes after standard therapies, including oral kinase inhibitors. We and others have previously reported on safety and efficacy of autologous CD19-targeted CAR T-cells for these patients; here we report safety and long-term follow-up of CAR T-cell therapy with or without conditioning chemotherapy for patients with R/R CLL and indolent B-cell non-Hodgkin lymphoma (B-NHL). METHODS: We conducted a phase 1 clinical trial investigating CD19-targeted CAR T-cells incorporating a CD28 costimulatory domain (19-28z). Seventeen of 20 patients received conditioning chemotherapy prior to CAR T-cell infusion. Five patients with CLL received ibrutinib at the time of autologous T-cell collection and/or CAR T-cell administration. RESULTS: This analysis included 16 patients with R/R CLL and 4 patients with R/R indolent B-NHL. Cytokine release syndrome (CRS) was observed in all 20 patients but grades 3 and 4 CRS and neurological events were uncommon (10% for each). Ex vivo expansion of T-cells and proportions of CD4+/CD8+ CAR T-cells with CD62L+CD127+ immunophenotype were significantly greater in patients on ibrutinib at leukapheresis. Three of 12 evaluable CLL patients receiving conditioning chemotherapy achieved CR (two had minimal residual disease-negative CR). All patients achieving CR remained progression-free at median follow-up of 53 months. CONCLUSION: Conditioning chemotherapy and 19-28z CAR T-cells were acceptably tolerated across investigated dose levels in heavily pretreated patients with R/R CLL and indolent B-NHL, and a subgroup of patients achieved durable CR. Ibrutinib therapy may modulate autologous T-cell phenotype. TRIAL REGISTRATION: ClinicalTrials.gov NCT00466531. FUNDING: Juno Therapeutics.

Challenges of driving CD30-directed CAR-T cells to the clinic.

Chimeric antigen receptor T (CAR-T) cells are a promising new treatment for patients with relapsed or refractory hematologic malignancies, including lymphoma. Given the success of CAR-T cells directed against CD19, new targets are being developed and tested, since not all lymphomas express CD19. CD30 is promising target as it is universally expressed in virtually all classical Hodgkin lymphomas, anaplastic large cell lymphomas, and in a proportion of other lymphoma types, including cutaneous T cell lymphomas and diffuse large B cell lymphomas. Preclinical studies with CD30-directed CAR-T cells support the feasibility of this approach. Recently, two clinical trials of CD30-directed CAR-T cells in relapsed/refractory CD30+ lymphomas, including Hodgkin lymphoma, have been reported with minimal toxicities noted and preliminary efficacy seen in a proportion of patients. However, improving the persistence and expansion of CAR-T cells is key to further enhancing the efficacy of this treatment approach. Future directions include optimizing the lymphodepletion regimen, enhancing migration to the tumor site, and combination with other immune regulators. Several ongoing and upcoming clinical trials of CD30-directed CAR-T cells are expected to further enhance this approach to treat patients with relapsed and refractory CD30+ lymphomas.

Plasma Exchange Can Be an Alternative Therapeutic Modality for Severe Cytokine Release Syndrome after Chimeric Antigen Receptor-T Cell Infusion: A Case Report.

BACKGROUND: Tumor immunotherapy with chimeric antigen receptor-T cells (CAR-T) is a promising new treatment for B-cell malignancies and has produced exciting results. However, cytokine release syndrome (CRS) is the most significant toxicity associated with this treatment and can be life-threatening. CASE PRESENTATION: A 23-year-old male patient had been diagnosed with relapsed and refractory B-cell acute lymphocytic leukemia. The patient was recruited into our CAR-T clinical trial, and 1 × 106/kg of engineered anti-CD19 CAR-T cells was administered. After infusion of CAR-T cells (day 0), the patient underwent a typical CRS reaction, with increases in fever, muscle soreness, and inflammatory cytokines. He was treated with antiallergic and antipyretic drugs, glucocorticoids, and tocilizumab (4 mg/kg, days 3 and 5). However, CRS was not under control, and his condition rapidly deteriorated. He was transferred to the intensive care unit, where dexamethasone 10 mg q6h was administered, and plasma exchange was performed, with 3,000 mL of plasma replaced by fresh frozen plasma per day for 3 consecutive days. His symptoms gradually improved, and the CRS-related symptoms were relieved. Additionally, a bone marrow smear showed no lymphoblast cells, and minimal residual disease was negative on day 28. The patient was eventually discharged in a normal condition. CONCLUSIONS: CRS is caused by an exaggerated systemic immune response, potentially resulting in organ damage that can be fatal. Although therapeutic plasma exchange is not included in CRS management guidelines, this case shows that plasma exchange is feasible in at least some patients with severe CRS.