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The adaptive T cell immune response requires cellular plasticity to generate distinct subsets with diverse functional and migratory capacities. Studies of CAR T cells have primarily focused on a limited number of phenotypic markers in blood, representing an incomplete view of CAR T cell complexity. Here, we adapted mass cytometry to simultaneously analyze trafficking and functional proteins expression in CD19 CAR T cells across patients' tissues, including leukapheresis T cells, CAR product, CAR T cells in peripheral blood, bone marrow, and cerebrospinal fluid post infusion and correlate them with phenotypes. This approach revealed spatiotemporal plasticity of CAR T cells. Patients' CAR product revealed upregulation in many trafficking and activation molecules compared to leukapheresis T cells as baseline. Including statistically significant upregulation in CD4 and CD8 integrin-β7, CD4 granzyme B, and CD11a as well as CD8 CD25 and CD95. Moreover, patients' tissues showed spatiotemporal alteration in trafficking, activation, maturation, and exhaustion features, with a distinct signature in the central nervous system niche. Compared to peripheral blood samples, cerebrospinal fluid samples were statistically significant enriched in CD4 and CD8 trafficking and memory phenotype proteins integrin β7, CCR7, CXCR4, and CD8 CD69. Our data provide a potential framework to remodel CAR T cells and enhance immunotherapy efficacy. [ABSTRACT FROM AUTHOR]

B-cell malignancies can potentially be cured by CD19 chimeric antigen receptor (CAR) T-cell therapy. Although clinical response rates can be up to 93% in acute lymphoblastic leukemia, treatment-related antigen loss and lack of therapeutic persistence contribute to disease relapse. These shortcomings of current CAR T-cell therapy indicate the need for biologically relevant target selection and for improving the efficacy and persistence of the CAR T cells, which we have addressed by developing a novel B-cell activating factor receptor (BAFF-R) CAR T-cell therapy with improved therapeutic persistence. BAFF-R is a B-cell survival receptor and highly expressed in B-cell malignancies. We developed a prototype CAR T cell that efficiently and specifically eliminated BAFF-R expressing human B-cell tumors in several xenogeneic mouse models, including models of CD19 antigen loss. We proceeded with translational development and validation of BAFF-R CAR T cells produced under current good manufacturing practices (cGMP). cGMP-grade BAFF-R CAR T cells underwent in vitro and in vivo validation in established models to confirm that the potency and efficacy of our original research modeling was replicated. Food and Drug Administration required release testing was performed to ensure our BAFF-R CAR T cells meet specifications for new drug products. Completing and exceeding these requirements, the data fully support the initiation of a first-in-human Phase 1 trial for BAFF-R-positive relapsed/refractory (r/r) B-ALL. [ABSTRACT FROM AUTHOR]

Virus helps drive CAR T cells: Chimeric antigen receptor (CAR) T cells are engineered to recognize specific antigens on tumor cells. In some cases, such as with the B cell antigen CD19, a naturally occurring antigen presents an effective target. In most cases, however, there is no antigen that is uniformly present on tumor cells but not normal tissues. Park et al. designed an oncolytic virus that delivers CD19 to tumor cells, which can then be targeted with CD19-specific CAR T cells. Killed tumor cells release additional copies of the virus, propagating CD19 expression to adjacent tumor cells. This combination strategy showed promising results in multiple mouse models of cancer. Chimeric antigen receptor (CAR)–engineered T cell therapy for solid tumors is limited by the lack of both tumor-restricted and homogeneously expressed tumor antigens. Therefore, we engineered an oncolytic virus to express a nonsignaling, truncated CD19 (CD19t) protein for tumor-selective delivery, enabling targeting by CD19-CAR T cells. Infecting tumor cells with an oncolytic vaccinia virus coding for CD19t (OV19t) produced de novo CD19 at the cell surface before virus-mediated tumor lysis. Cocultured CD19-CAR T cells secreted cytokines and exhibited potent cytolytic activity against infected tumors. Using several mouse tumor models, delivery of OV19t promoted tumor control after CD19-CAR T cell administration. OV19t induced local immunity characterized by tumor infiltration of endogenous and adoptively transferred T cells. CAR T cell–mediated tumor killing also induced release of virus from dying tumor cells, which propagated tumor expression of CD19t. Our study features a combination immunotherapy approach using oncolytic viruses to promote de novo CAR T cell targeting of solid tumors. [ABSTRACT FROM AUTHOR]

Acute lymphoblastic leukemia (ALL) in older adults presents a real challenge as a result of adverse disease biology and comorbidities that preclude delivering curative regimens. Conventional chemotherapy approaches have generally yielded unsatisfactory results in older patients with ALL as a result of excessive induction mortality, chemotherapy resistance of the leukemia, and the need to omit or dose reduce key drugs during the course of therapy because of adverse effects. Philadelphia chromosome–positive ALL represents about a quarter of newly diagnosed older adults, and the striking single-agent activity and excellent safety profile of tyrosine kinase inhibitors has allowed incorporation of these agents into therapy, significantly improving the outcome of older adults with Philadelphia chromosome–positive ALL. Allogeneic hematopoietic cell transplantation using reduced-intensity conditioning is a potentially curative approach in the older adult with ALL, and ironically, it may be better tolerated than intensive combination chemotherapy in a subset of older patients with ALL. Immunotherapies such as chimeric antigen receptor–modified T-cells, the bispecific T-cell–engaging antibody targeting CD19 (blinatumomab), and the antibody-drug conjugate targeting CD22 (inotuzumab) have shown safety and exceptional activity even in advanced ALL, and the efficacy of these agents has been observed irrespective of patient age. Several promising studies tailored specifically toward older adults with ALL are ongoing, with the majority of them incorporating novel immunotherapies, targeted therapies, or third-generation tyrosine kinase inhibitors into the front-line treatment regimen. [ABSTRACT FROM AUTHOR]

The article discusses a study that examined the association between breast implants and incident T-cell lymphomas in the California Teachers Study (CTS) cohort comprised of female public school professionals who enrolled in 1995 to 1996. Results indicate a positive association between breast implants and anaplastic large cell lymphoma (ALCL) risk. Possible reasons for the study's discordance with previous studies include differences in population sampling and insufficient sample size.

New therapeutic modalities are needed for ovarian cancer, the most lethal gynecologic malignancy. Recent clinical trials have demonstrated the impressive therapeutic potential of adoptive therapy using chimeric antigen receptor (CAR)-redirected T cells to target hematological cancers, and emerging studies suggest a similar impact may be achieved for solid cancers. We sought determine whether genetically-modified T cells targeting the CE7-epitope of L1-CAM, a cell adhesion molecule aberrantly expressed in several cancers, have promise as an immunotherapy for ovarian cancer, first demonstrating that L1-CAM was highly over-expressed on a panel of ovarian cancer cell lines, primary ovarian tumor tissue specimens, and ascites-derived primary cancer cells. Human central memory derived T cells (TCM) were then genetically modified to express an anti-L1-CAM CAR (CE7R), which directed effector function upon tumor antigen stimulation as assessed by in vitro cytokine secretion and cytotoxicity assays. We also found that CE7R+ T cells were able to target primary ovarian cancer cells. Intraperitoneal (i.p.) administration of CE7R+ TCM induced a significant regression of i.p. established SK-OV-3 xenograft tumors in mice, inhibited ascites formation, and conferred a significant survival advantage compared with control-treated animals. Taken together, these studies indicate that adoptive transfer of L1-CAM-specific CE7R+ T cells may offer a novel and effective immunotherapy strategy for advanced ovarian cancer. [ABSTRACT FROM AUTHOR]

Immune checkpoint blockade has emerged as a potent new tool in the war on cancer. However, only a subset of cancer patients benefit from this therapeutic modality, sparking a search for combination therapies to increase the fraction of responding patients. We argue here that inhibition of protein phosphatase 2A (PP2A) is a promising approach to increase responses to immune checkpoint blockade and other therapies that rely on the presence of tumor‐reactive T cells. Inhibition of PP2A increases neoantigen expression on tumor cells, activates the cGAS/STING pathway, suppresses regulatory T cells, and increases cytotoxic T cell activation. In preclinical models, inhibition of PP2A synergizes with immune checkpoint blockade and emerging evidence indicates that patients who have tumors with mutations in PP2A respond better to immune checkpoint blockade. Therefore, inhibition of PP2A activity may be an effective way to sensitize cancer cells to immune checkpoint blockade and cell‐based therapies using tumor‐reactive T cells. [ABSTRACT FROM AUTHOR]

Human CD8+effector T cells derived from CD45RO+CD62L+precursors enriched for central memory (TCM) precursors retain the capacity to engraft and reconstitute functional memory upon adoptive transfer, whereas effectors derived from CD45RO+CD62L−precursors enriched for effector memory precursors do not. Here we sought to compare the engraftment fitness and function of CD8+effector T cells derived from CD45RA+CD62L+precursors enriched for naïve and stem cell memory precursors (TN/SCM) with that of TCM. We found that cytotoxic T cells (CTLs) derived from TCMtranscribed higher levels of CD28, FOS, INFγ, Eomesodermin (Eomes), and lower levels of BCL2L11, maintained higher levels of phosphorylated AKT, and displayed enhanced sensitivity to the proliferative and anti-apoptotic effects of γ-chain cytokines compared to CTLs derived from TN/SCM. Higher frequencies of CTLs derived from TCMretained CD28 expression and upon activation secreted higher levels of IL-2. In NOD/ScidIL-2RγCnullmice, CD8+TCMderived CTLs engrafted to higher frequencies in response to human IL-15 and mounted robust proliferative responses to an immunostimulatory vaccine. Similarly, CD8+TCMderived CD19CAR+CTLs exhibited superior antitumor potency following adoptive transfer compared to their CD8+TN/SCMderived counterparts. These studies support the use of TCMenriched cell products for adoptive therapy of cancer. [ABSTRACT FROM PUBLISHER]

Clinical trials are currently testing whether induction of haploidentical mixed chimerism (Haplo-MC) induces organ transplantation tolerance. Whether Haplo-MC can be used to treat established autoimmune diseases remains unknown. Here, we show that established autoimmunity in euthymic and adult-thymectomized NOD (H-2g7) mice was cured by induction of Haplo-MC under a non-myeloablative anti-thymocyte globulin-based conditioning regimen and infusion of CD4+ T cell-depleted hematopoietic graft from H-2b/g7 F1 donors that expressed autoimmune-resistant H-2b or from H-2s/g7 F1 donors that expressed autoimmune-susceptible H-2s. The cure was associated with enhanced thymic negative selection, increased thymic Treg (tTreg) production, and anergy or exhaustion of residual host-type autoreactive T cells in the periphery. The peripheral tolerance was accompanied by expansion of donor- and host-type CD62L-Helios+ tTregs as well as host-type Helios-Nrp1+ peripheral Tregs (pTregs) and PD-L1hi plasmacytoid DCs (pDCs). Depletion of donor- or host-type Tregs led to reduction of host-type PD-L1hi pDCs and recurrence of autoimmunity, whereas PD-L1 deficiency in host-type DCs led to reduction of host-type pDCs and Helios-Nrp1+ pTregs. Thus, induction of Haplo-MC reestablished both central and peripheral tolerance through mechanisms that depend on allo-MHC+ donor-type DCs, PD-L1hi host-type DCs, and the generation and persistence of donor- and host-type tTregs and pTregs. [ABSTRACT FROM AUTHOR]

• Establishing a quality program for immune effector cell (IEC) therapy requires a multidisciplinary approach. • Considerations such as standardization of patient care management and data management are crucial for a new IEC quality program. • IEC quality programs must align accreditation and federal requirements with institutional policies. • Auditing and reporting are essential elements of IEC quality programs. As the world of cellular therapy expands to include immune effector cell (IEC) products such as commercial chimeric antigen receptor (CAR) T cells, quality management (QM) professionals are faced with creating either new IEC stand-alone programs or expand existing hematopoietic cell transplantation (HCT) programs to promote patient safety and be aligned with quality, regulatory, and accreditation requirements. The team professionals at City of Hope (COH) recently expanded the quality HCT program to include IEC products and, in doing so, implemented new regulatory infrastructure while maintaining high quality patient care. At COH, we developed the quality structure of our cellular therapy program through collaborations between quality, regulatory, and CAR T patient care committees, which included physicians and nurse coordinators. To ensure the quality of our program, we monitor data collection and reporting, perform quarterly proactive audits of, for example, outcome analysis, and measure selected end-points for benchmarking purposes. QM professionals play a critical role in the monitoring and evaluation processes and provide guidance on how to implement accreditation requirements and what impact the requirements may have on care management. Here we describe the process by which COH expanded our HCT QM program to include IEC therapy. We share examples of how we developed our overall program structure and other key items such as how we addressed patient care management and accreditation to apprise other programs that wish to create and/or expand existing programs. [ABSTRACT FROM AUTHOR]

High-grade (WHO grades III-IV) glioma remains one of the most lethal human cancers. Adoptive transfer of tumor-targeting chimeric antigen receptor (CAR)-redirected T cells for high-grade glioma has revealed promising indications of anti-tumor activity, but objective clinical responses remain elusive for most patients. A significant challenge to effective immunotherapy is the highly heterogeneous structure of these tumors, including large variations in the magnitudes and distributions of target antigen expression, observed both within individual tumors and between patients. To obtain a more detailed understanding of immunotherapy target antigens within patient tumors, we immunochemically mapped at single cell resolution three clinically-relevant targets, IL13Rα2, HER2 and EGFR, on tumor samples drawn from a 43-patient cohort. We observed that within individual tumor samples, expression of these antigens was neither random nor uniform, but rather that they mapped into local neighborhoods – phenotypically similar cells within regions of cellular tumor – reflecting not well understood properties of tumor cells and their milieu. Notably, tumor cell neighborhoods of high antigen expression were not arranged independently within regions. For example, in cellular tumor regions, neighborhoods of high IL13Rα2 and HER2 expression appeared to be reciprocal to those of EGFR, while in areas of pseudopalisading necrosis, expression of IL13Rα2 and HER2, but not EGFR, appeared to reflect the radial organization of tumor cells around hypoxic cores. Other structural features affecting expression of immunotherapy target antigens remain to be elucidated. This structured but heterogeneous organization of antigen expression in high grade glioma is highly permissive for antigen escape, and combinatorial antigen targeting is a commonly suggested potential mitigating strategy. Deeper understanding of antigen expression within and between patient tumors will enhance optimization of combination immunotherapies, the most immediate clinical application of the observations presented here being the importance of including (wild-type) EGFR as a target antigen. [ABSTRACT FROM AUTHOR]

The success of adoptive therapy using chimeric antigen receptor (CAR)-expressing T cells partly depends on optimal CAR design. CARs frequently incorporate a spacer/linker region based on the constant region of either IgG1 or IgG4 to connect extracellular ligand-binding with intracellular signaling domains. Here, we evaluated the potential for the IgG4-Fc linker to result in off-target interactions with Fc gamma receptors (FcγRs). As proof-of-principle, we focused on a CD19-specific scFv-IgG4-CD28-zeta CAR and found that, in contrast to CAR-negative cells, CAR+ T cells bound soluble FcγRs in vitro and did not engraft in NSG mice. We hypothesized that mutations to avoid FcγR binding would improve CAR+ T cell engraftment and antitumor efficacy. Thus, we generated CD19-specific CARs with IgG4-Fc spacers that had either been mutated at two sites (L235E; N297Q) within the CH2 region (CD19R(EQ)) or incorporated a CH2 deletion (CD19Rch2Δ). These mutations reduced binding to soluble FcγRs without altering the ability of the CAR to mediate antigen-specific lysis. Importantly, CD19R(EQ) and CD19Rch2Δ T cells exhibited improved persistence and more potent CD19-specific antilymphoma efficacy in NSG mice. Together, these studies suggest that optimal CAR function may require the elimination of cellular FcγR interactions to improve T cell persistence and antitumor responses. [ABSTRACT FROM AUTHOR]

• Autologous T cells derived from MDS patients can be successfully transduced and are highly active in multiple functional assays. • A xenograft model was developed in which high-risk MDS specimens engraft to high levels and thus provide an in vivo model for characterization of MDS stem cell behavior. • Autologous T cells are highly active in our xenograft model and selectively target the CD123-positive population. Importantly, CD123 CAR T cells did not exhibit appreciable targeting of normal hematopoietic stem and progenitor cells. Myelodysplastic syndrome (MDS) is a group of heterogeneous disorders caused by ineffective hematopoiesis and characterized by bone marrow dysplasia and cytopenia. Current treatment options for MDS are limited to supportive care, hypomethylating agents, and stem cell transplant. Most patients eventually succumb to the disease or progress to leukemia. Previously, we found that CD123 can be used to delineate MDS stem cells in patients at high risk for MDS and that the CD123-positive population is biologically distinct from normal hematopoietic stem cells. Furthermore, selective targeting of MDS stem cells can dramatically reduce tumor burden in preclinical models. On the basis of these findings, we propose CD123 as a candidate target for chimeric antigen receptor (CAR) T-cell therapy in high-risk MDS patients. To test this concept, we employed a CAR lentiviral vector containing a CD123-specific single-chain variable fragment in combination with the CD28 costimulatory domain, CD3ζ signaling domain, and truncated estimated glomerular filtration rate. Utilizing this system, we illustrate that CD123 CAR can be expressed on both healthy donor and MDS patient-derived T lymphocytes with high efficiency, leading to the successful elimination of MDS stem cells both in vitro and in patient-derived xenografts. These results provide the concept for the use of CD123-targeted CAR T cells as a therapeutic option for patients with MDS. [ABSTRACT FROM AUTHOR]