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Understanding the mechanisms that regulate T cell immunity is critical for the development of effective therapies for diseases associated with T cell dysfunction, including autoimmune diseases, chronic infections, and cancer. Co-inhibitory "checkpoint molecules," such as programmed cell death protein-1, balance excessive or prolonged immune activation by T cell–intrinsic signaling. Here, by screening for mediators of natural killer (NK) cell recognition on T cells, we identified the immunoglobulin superfamily ligand B7H6 to be highly expressed by activated T cells, including patient-infused CD19-targeting chimeric antigen receptor (CAR) T cells. Unlike other checkpoint molecules, B7H6 mediated NKp30-dependent recognition and subsequent cytolysis of activated T cells by NK cells. B7H6+ T cells were prevalent in the tissue and blood of several diseases, and their abundance in tumor tissue positively correlated with clinical response in a cohort of patients with immune checkpoint inhibitor–treated esophageal cancer. In humanized mouse models, NK cell surveillance via B7H6 limited the persistence and antitumor activity of CAR T cells, and its genetic deletion enhanced T cell proliferation and persistence. Together, we provide evidence of B7H6 protein expression by activated T cells and suggest the B7H6-NKp30 axis as a therapeutically actionable NK cell–dependent immune checkpoint that regulates human T cell function. Editor's summary: Natural killer (NK) cells can eliminate infected or malignant cells, but they are also believed to be capable of killing host immune cells. By screening NK cell ligands on human T cells, Kilian et al. found that the immunoglobulin superfamily ligand B7H6 promotes cytolysis of activated T cells by NK cells. In leukemia-bearing humanized mice, NK cells restricted the antitumor activity of chimeric antigen receptor (CAR) T cells in a B7H6-dependent manner. A higher ratio of intratumoral NK to T cells was associated with poor response to immune checkpoint inhibition in a cohort of patients with esophageal cancer. These findings demonstrate that B7H6 recognition by NK cells can restrict human antitumor T cell responses. —Claire Olingy [ABSTRACT FROM AUTHOR]

Light chain amyloidosis (AL) is a rare disease caused by the generalized deposition of misfolded free light chains. Patients with immunoglobulin M gammopathy (IgM) and indolent B-cell lymphoma such as marginal zone lymphoma (MZL) may in some instances develop AL amyloidosis. So far, CAR T cells for AL amyloidosis have only been reported utilizing the B cell maturation antigen as target, while CD19 has so far not been used in AL amyloidosis. We report the case of a 71-year-old male, diagnosed with systemic AL kappa amyloidosis and MZL, receiving third-generation CAR T cell therapy targeting CD19. Prior treatment included bendamustine/rituximab and cyclophosphamide/ dexamethasone with subsequent autologous stem cell transplantation. CAR T application was well tolerated despite heart and kidney amyloid manifestations, and only early low-grade procedure-specific toxicities were observed. A continuous decrease in IgM, kappa light chains and kappa-to-lambda light chain difference was observed in the patient from day + 30 on, resulting in a deep hematological response six months after treatment. In summary, we present a novel case of CAR T cell treatment with third generation CD19 directed infusion for AL amyloidosis with an underlying secretory active B cell lymphoma, showing that this is an effective treatment modality and can be applied to patients with subsequent AL amyloidosis. [ABSTRACT FROM AUTHOR]

We investigated ≥ grade 3 (CTC-AE) organ toxicities for commercial CD19 chimeric antigen receptor T cell (CAR-T cell) products in 492 patients (Axi-Cel; n = 315; Tisa-Cel; n = 177) with Large B-cell Lymphoma in the European Society for Blood and Marrow Transplantation (EBMT) CAR-T registry. The incidence of ≥ grade 3 organ toxicities during the first 100 days after CAR-T was low and the most frequent were: renal (3.0%), cardiac (2.3%), gastro-intestinal (2.3%) and hepatic (1.8%). The majority occurred within three weeks after CAR-T cell therapy. Overall survival was 83.1% [79.8-86.5; 95% CI] at 3 months and 53.5% [49-58.4; 95% CI] at one year after CAR-T. The most frequent cause of death was tumour progression (85.1%). Non-relapse mortality was 3.1% [2.3-4.1; 95% CI] at 3 months and 5.2% [4.1-6.5; 95% CI] at one year after CAR-T. The most frequent causes of non-relapse mortality were cell-therapy-related toxicities including organ toxicities (6.4% of total deaths) and infections (4.4% of total deaths). Our data demonstrates good safety in the European real-world setting. [ABSTRACT FROM AUTHOR]

• This article addresses the possible role of allogeneic hematopoietic cell transplantation (allo-HCT) for relapsed and refractory diffuse large B cell lymphoma in the chimeric antigen receptor-engineered T (CART) cell era. • Allo-HCT should be explored for patients failing CART therapy. • Allo-HCT should be considered when CART therapy is not feasible or available. • Allo-HCT and CART outcome data should be collected and analyzed in registries. Chimeric antigen receptor-engineered T (CART) cells are a promising new treatment option for patients with multiply relapsed and refractory (R/R) diffuse large B cell lymphoma (DLBCL). Because of the favorable outcome data reported for CART cells, uncertainty is emerging if there is still a role for allogeneic hematopoietic cell transplantation (allo-HCT) in the treatment of R/R DLBCL. This article provides an overview of available evidence and theoretical considerations to put these 2 types of cellular immunotherapy (CI) into perspective. Altogether, current data suggest that CART cells are preferred now over transplantation as first-choice CI in many clinical situations. However, the majority of patients will fail CART therapy, resulting in an unmet medical need where allo-HCT could be beneficial. In contrast, employing allo-HCT instead of CART cells as first CI should be presently restricted to situations where CART cell therapy is deemed not feasible or useful, such as patients with refractory cytopenia or incipient myelodysplastic syndrome. However, allo-HCT remains a standard treatment option as first CI for patients with chemosensitive R/R DLBCL when CARTs are not available or transplantation is preferred by the patient. Continuous collection and analysis of CI outcome data by professional registries appear to be of key importance for developing rational strategies of CI allocation and sequencing. [ABSTRACT FROM AUTHOR]

This retrospective single-center analysis studied the impact of the conditioning and the graft-versus-host disease (GVHD) prophylaxis on outcome in unselected patients allografted for chronic myelomonocytic leukemia (CMML) and acute myeloid leukemia (AML) secondary to documented prior CMML. A total of 44 patients (median age 61 years) allografted between 2002 and 2019 in our institution were analyzed. Fifteen patients had secondary AML. The conditioning regimen was fractionated 6-8 Gy total body irradiation (TBI) in combination with fludarabine in 33 (75%) patients. Eleven patients (25%) received alkylator-based conditioning therapy without TBI. For GVHD prophylaxis, a calcineurin inhibitor (CNI) backbone in combination with methotrexate (MTX) or mycophenolate mofetil (MMF) was applied in 21 and 23 patients, respectively. All patients allografted from an unrelated donor (UD) received antithymocyte globuline. In univariate analysis of the entire cohort, TBI-based conditioning and MMF-containing immunosuppression were associated with improved leukemia-free survival (LFS, HR 0.16, P < 0.001 and HR 0.41, P = 0.030, respectively). After stratification according to conditioning and GVHD prophylaxis into four groups (TBI-MMF [n = 17], TBI-MTX [n = 16], alkylator-MMF [n = 6], alkylator-MTX [n = 5]), TBI-MMF was associated with improved overall survival (OS) and LFS (P = 0.001 and P < 0.001, respectively). Patient and disease characteristics did not differ between the groups. The associations of TBI-based conditioning and MMF with prolonged LFS were observed across the CMML (n = 29), secondary AML (n = 15), and UD allograft (n = 34) subgroups. In summary, our study suggests that allografting based on intermediate-dose TBI conditioning and MMF-containing GVHD prophylaxis is associated with increased disease control in CMML. Larger (registry-based) studies are warranted to confirm our findings. [ABSTRACT FROM AUTHOR]

Keywords: CAR T cells; cell therapy; costs; gene therapy; Immunotherapy EN CAR T cells cell therapy costs gene therapy Immunotherapy 514 515 2 11/27/20 20210115 NES 210115 We would like to comment on the article "Cost of decentralized CAR T cell production in an academic non-profit setting" by Ran et al1 published in your prestigious journal on June 14, 2020. Accordingly, is it possible that the authors simply calculated the costs for a research product and then added a gross estimate of regulatory costs? CAR T cells, cell therapy, costs, gene therapy, Immunotherapy. [Extracted from the article]

Simple Summary: Chimeric antigen receptor T (CAR-T) cells have become clinical practice for the treatment of acute lymphoblastic leukemia and non-Hodgkin lymphoma. The aim of this retrospective study was to assess infection complications after lymphodepletion and CAR-T cell therapy. Infections were commonly detected, but manageable in most cases. Fast and appropriate identification as well as treatment were critical, especially in this very vulnerable patient group. Effective strategies to prevent infections as well as adequate medical management also include standardized prophylaxis and additional supportive therapy. Chimeric antigen receptor T (CAR-T) cell therapy has proven to be very effective in patients with relapsed/refractory acute lymphoblastic leukemia (ALL) and non-Hodgkin lymphoma (NHL). However, infections—related either due to lymphodepletion or the CAR-T cell therapy itself—can result in severe and potentially life-threatening complications, while side effects such as cytokine release syndrome (CRS) might complicate differential diagnosis. Sixty-seven dosings of CAR-T cells in sixty adult patients with NHL (85%) and ALL (15%) receiving CAR-T cell therapy were assessed for infectious complications. Almost two-thirds of patients (61%) developed fever following lymphodepletion and CAR-T cell dosing. Microbiological or radiological findings were observed in 25% of all cases (bacterial 12%, viral 5%, fungal 8%). Inpatient infections were associated with more lines of therapy and more severe CRS. However, overall serious complications were rare after CAR-T therapy, with one patient dying of infection. Pathogen detection after inpatient stay was infrequent and mostly occurred in the first 90 days after dosing. Infections in CAR-T cell treated patents are common. Fast and suitable identification and treatment are crucial in these heavily pretreated and immunocompromised patients. In most cases infectious complications are manageable. Nonetheless, standardized anti-infective prophylaxis and supportive therapy are mandatory to reduce morbidity and mortality in CAR-T cell therapy. [ABSTRACT FROM AUTHOR]

Simple Summary: To monitor patients after CAR T cell treatment, measuring frequencies of chimeric antigen receptor (CAR) T cells is crucial. However, experimental assays to quantify CAR T cells are lacking. Here, we describe a quantitative single copy gene-based PCR approach to measure frequencies of CAR T cells based on the FMC63 single chain variable fragment (scFv) including commercially available CAR T cell products. Besides enabling to monitor development of CAR T cells after treatment and guide further therapeutic decisions, this quantification assay proved highly useful for diagnosis of CAR T cell associated neurotoxic side effects. Overall, this quantification approach contributes significantly to the better monitoring and safety of treatment of patients with CAR T cells. Chimeric antigen receptor (CAR) T cell (CART) therapy has been established as a treatment option for patients with CD19-positive lymphoid malignancies in both the refractory and the relapsed setting. Displaying significant responses in clinical trials, two second-generation CART products directed against CD19, axicabtagene ciloleucel (axi-cel) and tisagenlecleucel (tisa-cel), have been approved and integrated into the clinical routine. However, experimental assay for quantitative monitoring of both of these CART products in treated patients in the open domain are lacking. To address this issue, we established and validated a quantitative single copy gene (SCG)-based duplex (DP)-PCR assay (SCG-DP-PCR) to quantify CARTs based on the FMC63 single chain variable fragment (scFv), i.e., axi-cel and tisa-cel. This quantitative PCR (qPCR) approach operates without standard curves or calibrator samples, offers a tool to assess cellular kinetics of FMC63 CARTs and allows direct comparison of CART-copies in axi-cel versus tisa-cel patient samples. For treating physicians, SCG-DP-PCR is an important tool to monitor CARTs and guide clinical decisions regarding CART effects in respective patients. [ABSTRACT FROM AUTHOR]

Background: T lymphocyte collection through leukapheresis is an essential step for chimeric antigen receptor T (CAR-T) cell therapy. Timing of apheresis is challenging in heavily pretreated patients who suffer from rapid progressive disease and receive T cell impairing medication. Methods: A total of 75 unstimulated leukaphereses were analyzed including 45 aphereses in patients and 30 in healthy donors. Thereof, 41 adult patients with Non-Hodgkin's lymphoma (85%) or acute lymphoblastic leukemia (15%) underwent leukapheresis for CAR-T cell production. Results: Sufficient lymphocytes were harvested from all patients even from those with low peripheral lymphocyte counts of 0.18/nL. Only four patients required a second leukapheresis session. Leukapheresis products contained a median of 98 × 108 (9 - 341 × 108) total nucleated cells (TNC) with 38 × 108 (4 - 232 × 108) CD3+ T cells. Leukapheresis products from healthy donors as well as from patients in complete remission were characterized by high TNC and CD3+ T lymphocyte counts. CAR-T cell products could be manufactured for all but one patient. Conclusions: Sufficient yield of lymphocytes for CAR-T cell production is feasible also for patients with low peripheral blood counts. Up to 12–15 L blood volume should be processed in patients with absolute lymphocyte counts ≤ 1.0/nL. [ABSTRACT FROM AUTHOR]

Despite high response rates after initial chemotherapy in patients with acute myeloid leukemia (AML), relapses occur frequently, resulting in a five-year-survival by <30% of the patients. Hitherto, allogeneic hemotopoietic stem cell transplantation (allo-HSCT) is the best curative treatment option in intermediate and high risk AML. It is the proof-of-concept for T cell-based immunotherapies in AML based on the graft-versus-leukemia (GvL)-effect, but it also bears the risk of graft-versus-host disease. CD19-targeting therapies employing chimeric antigen receptor (CAR) T cells are a breakthrough in cancer therapy. A similar approach for myeloid malignancies is highly desirable. This article gives an overview on the state-of-the art of preclinical and clinical studies on suitable target antigens for CAR T cell therapy in AML patients. [ABSTRACT FROM AUTHOR]

• ECP was able to increase Tfh cells to ameliorate GvHD. • Upregulation of Th22 cells was observed in aGvHD patients with CR. • Tim-3 expression was downregulated on effector T cells by ECP. • ECP shows immunomodulatory effects in GvHD setting. Extracorporeal photopheresis (ECP), a personalized cellular immunotherapy, constitutes a promising treatment for steroid-refractory/-resistant graft-versus-host disease (SR-GvHD), with encouraging clinical response rates. To further investigate its mechanism of action, ECP's effects on T helper (Th) cells as well as on expression of immune checkpoint (PD-1 and Tim-3) and apoptotic (Fas receptor [FasR]) molecules were investigated in 27 patients with SR-GvHD. Our data show that GvHD patients had significantly higher levels of Th2, Th17, Th22 and granulocyte-macrophage colony-stimulating factor (GM-CSF)-positive Th (ThG) cells and clearly lower levels of T follicular helper (Tfh) cells, including Th1- and Th2-like cells, compared with healthy donors. ECP therapy for GvHD was effective through the modulation of different Th subsets: increases of Th22 (1.52-fold) and Tfh cells (1.48-fold) in acute GvHD (aGvHD) and increases of Th2-like Tfh cells (1.74-fold) in chronic GvHD (cGvHD) patients were associated with clinical response. Expression of FasR was further upregulated in CD4+CD8+ T cells. Additionally, Tim-3–expressing effector T cells associated with the severity of GvHD were reduced. Taken together, these data show that ECP therapy exerts immunomodulatory effects by promoting a balanced immune reconstitution and inducing immune tolerance. Therefore it represents an attractive option for the treatment of GvHD. [ABSTRACT FROM AUTHOR]

Enhanced in vivo expansion, long-term persistence of chimeric antigen receptor T (CART) cells, and efficient tumor eradication through these cells are linked to the proportion of less-differentiated cells in the CART cell product. Retronectin is well established as an adjuvant for improved retroviral transduction, while its property to enrich less-differentiated T cells is less known. In order to increase these subsets, this study investigated the effects of retronectin-mediated T-cell activation for CD19-specific CART cell production. Peripheral blood mononuclear cells of healthy donors and untreated chronic lymphocytic leukemia (CLL) patients without or with positive selection for CD3+ T cells were transduced with a CD19.CAR.CD28.CD137zeta third-generation retroviral vector. Activation of peripheral blood mononuclear cells was performed by CD3/CD28, CD3/CD28/retronectin, or CD3/retronectin. Interleukin-7 and -15 were supplemented to all cultures. Retronectin was used in all three activation protocols for retroviral transduction. Expansion was assessed by trypan blue staining. Viability, transduction efficiency, immune phenotype, and cytokine production were longitudinally analyzed by flow cytometry. Cytotoxic capacity of generated CART cells was evaluated using a classical chromium-51 release assay. Retronectin-mediated activation resulted in an enrichment of CD8+ cytotoxic CART cells and less-differentiated naïve-like T cells (CD45RA+CCR7+). Retronectin-activated CART cells showed increased cytotoxic activity. However, activation with retronectin decreased viability, expansion, transduction efficiency, and cytokine production, particularly of CLL patient-derived CART cells. Both retronectin-mediated activation protocols promoted a less-differentiated CART cell phenotype without comprising cytotoxic properties of healthy donor–derived CART cells. However, up-front retronectin resulted in reduced viability and expansion in CLL patients. This effect is probably attributed to the retronectin-mediated activation of B cells with prolonged CLL persistence. Consequently, CART cell expansion and generation failed. In summary, activation with retronectin should be performed with caution and may be limited to patients without a higher percentage of tumor cells in the peripheral blood. [ABSTRACT FROM AUTHOR]

Novel therapies with chimeric antigen receptor (CAR)-transduced T cells (TCs) sparked new hope for patients with relapsed or refractory CD19-positive leukemia or lymphoma even after stem cell therapies. This review focuses on CARs recognizing the B cell antigen CD19. Both retroviral and lentiviral vectors are used, encoding various anti-CD19 CAR constructs comprising costimulatory molecules such as CD28, CD137/4-1BB, and OX40 either alone (second-generation CARs) or in combination (third-generation CARs). Current, up-to-date published studies on anti-CD19 CAR therapy for acute lymphoblastic leukemia (ALL), chronic lymphocytic leukemia (CLL), and non-Hodgkin lymphoma (NHL) with observed side effects are discussed and an outlook on 58 ongoing trials is given. Clinical responses were achieved in up to 81% of ALL, 50% of CLL, and 40% of NHL patients. Factors with potential influence on the clinical outcome might be the design of the vector, the preconditioning regimen, and the number and quality of transfused CAR TCs. The applicability of clinical CAR TC therapy might include relapse after allogeneic stem cell transplantation (alloSCT), and ineligibility for or 'bridging' until alloSCT. In summary, CAR therapy represents a highly promising treatment option even in heavily pretreated patients. [ABSTRACT FROM AUTHOR]