Dynamics of T-cell receptor repertoire in patients with ankylosing spondylitis after biologic therapy.

INTRODUCTION: Ankylosing spondylitis (AS) is a chronic inflammatory autoimmune disease in which T-cell immune responses play important roles. AS has been characterized by altered T-cell receptor (TCR) repertoire profiles, which are thought to be caused by expansion of disease-related TCR clonotypes. However, how biological agents affect the TCR repertoire status and whether their therapeutic outcomes are associated with certain features or dynamic patterns of the TCR repertoire are still elusive. MATERIAL AND METHODS: We collected clinical samples from AS patients pre- and post-treatment with biologics. TCR repertoire sequencing was conducted to investigate associations of TCRα and TCRß repertoire characteristics with disease activity and inflammatory indicators/cytokines. RESULTS: Our results showed that good responders were associated with an increase in the TCR repertoire diversity with higher proportions of contracted TCR clonotypes. Additionally, we further identified a positive correlation between TCR repertoire diversity and interleukin (IL)-23 levels in AS patients. A network analysis revealed that contracted AS-associated TCR clonotypes with the same complementary-determining region 3 (CDR3) motifs, which represented high probabilities of sharing TCR specificities to AS-related antigens, were dominant in good responders of AS after treatment with biologic therapies. CONCLUSIONS: Our findings suggested an important connection between TCR repertoire changes and therapeutic outcomes in biologic-treated AS patients. The status and dynamics of TCR repertoire profiles are useful for assessing the prognosis of biologic treatments in AS patients.

Microbial metabolite butyrate promotes anti-PD-1 antitumor efficacy by modulating T cell receptor signaling of cytotoxic CD8 T cell.

Recent studies have demonstrated that the antitumor immunity of immune cells can be modulated by gut microbiota and their metabolites. However, the underlying mechanisms remain unclear. Here, we showed that the serum butyric acid level is positively correlated with the expression of programmed cell death-1 (PD-1) on circulating CD8+ and Vγ9 Vδ2 (Vδ2+) T cells in patients with non-small cell lung cancer (NSCLC). Responder NSCLC patients exhibited higher levels of serum acetic acid, propionic acid, and butyric acid than non-responders. Depletion of the gut microbiota reduces butyrate levels in both feces and serum in tumor-bearing mice. Mechanistically, butyrate increased histone 3 lysine 27 acetylation (H3K27ac) at the promoter region of Pdcd1 and Cd28 in human CD8+ T cells, thereby promoting the expression of PD-1/CD28 and enhancing the efficacy of anti-PD-1 therapy. Butyrate supplementation promotes the expression of antitumor cytokines in cytotoxic CD8+ T cells by modulating the T-cell receptor (TCR) signaling pathway. Collectively, our findings reveal that the metabolite butyrate of the gut microbiota facilitates the efficacy of anti-PD-1 immunotherapy by modulating TCR signaling of cytotoxic CD8 T cells, and is a highly promising therapeutic biomarker for enhancing antitumor immunity.

Chimeric TIM-4 receptor-modified T cells targeting phosphatidylserine mediates both cytotoxic anti-tumor responses and phagocytic uptake of tumor-associated antigen for T cell cross-presentation.

To leverage complementary mechanisms for cancer cell removal, we developed a novel cell engineering and therapeutic strategy co-opting phagocytic clearance and antigen presentation activity into T cells. We engineered a chimeric engulfment receptor (CER)-1236, which combines the extracellular domain of TIM-4, a phagocytic receptor recognizing the "eat me" signal phosphatidylserine, with intracellular signaling domains (TLR2/TIR, CD28, and CD3ζ) to enhance both TIM-4-mediated phagocytosis and T cell cytotoxic function. CER-1236 T cells demonstrate target-dependent phagocytic function and induce transcriptional signatures of key regulators responsible for phagocytic recognition and uptake, along with cytotoxic mediators. Pre-clinical models of mantle cell lymphoma (MCL) and EGFR mutation-positive non-small cell lung cancer (NSCLC) demonstrate collaborative innate-adaptive anti-tumor immune responses both in vitro and in vivo. Treatment with BTK (MCL) and EGFR (NSCLC) inhibitors increased target ligand, conditionally driving CER-1236 function to augment anti-tumor responses. We also show that activated CER-1236 T cells exhibit superior cross-presentation ability compared with conventional T cells, triggering E7-specific TCR T responses in an HLA class I- and TLR-2-dependent manner, thereby overcoming the limited antigen presentation capacity of conventional T cells. Therefore, CER-1236 T cells have the potential to achieve tumor control by eliciting both direct cytotoxic effects and indirect-mediated cross-priming.

Integrative tumour mutation burden with CD39 and PD-L1 for the prediction of response to PD-L1 blockade and adjuvant chemotherapy in muscle-invasive bladder cancer patients.

BACKGROUND: CD39, a rate-limiting enzyme to convert extracellular ATP (eATP) to adenosine, has been reported to be a key modulator of immune response, but its correlation with therapeutic sensitivity remains obscure. We conducted this study to determine whether the integration of CD39 and traditional biomarkers could improve the prediction of responsiveness to PD-L1 blockade and platinum-based chemotherapy. METHODS: We retrospectively enrolled a total of 760 patients from IMvigor210 trial, TCGA database and Zhongshan Hospital in this study. We constructed the CPT scoring system based on CD39, PD-L1 and tumour mutation burden (TMB) and validated its efficacy in predicting therapeutic responsiveness in MIBC patients. Kaplan-Meier survival and Cox regression analyses were applied to assess clinical outcomes of patients. RESULTS: The CPT scoring system could predict the response to PD-L1 blockade and platinum-based chemotherapy. The CPT score was positively correlated with APOBEC mutational signature and SNV neoantigens enrichment, antigen presentation, and TCR signalling. High CPT score also indicated the inflamed immune phenotype and basal/squamous molecular subtype. CONCLUSIONS: CD39 expression is closely correlated with the immunogenic contexture of MIBC. Integrating CD39 with PD-L1 and TMB could stratify the sensitivity of patients with MIBC to PD-L1 blockade and platinum-based chemotherapy.

CAR-NK Cells in the Treatment of Solid Tumors.

CAR-T (chimeric antigen receptor T) cells have emerged as a milestone in the treatment of patients with refractory B-cell neoplasms. However, despite having unprecedented efficacy against hematological malignancies, the treatment is far from flawless. Its greatest drawbacks arise from a challenging and expensive production process, strict patient eligibility criteria and serious toxicity profile. One possible solution, supported by robust research, is the replacement of T lymphocytes with NK cells for CAR expression. NK cells seem to be an attractive vehicle for CAR expression as they can be derived from multiple sources and safely infused regardless of donor-patient matching, which greatly reduces the cost of the treatment. CAR-NK cells are known to be effective against hematological malignancies, and a growing number of preclinical findings indicate that they have activity against non-hematological neoplasms. Here, we present a thorough overview of the current state of knowledge regarding the use of CAR-NK cells in treating various solid tumors.

Applications of CRISPR Genome Editing to Advance the Next Generation of Adoptive Cell Therapies for Cancer.

Adoptive cell therapy (ACT) for cancer shows tremendous potential; however, several challenges preclude its widespread use. These include poor T-cell function in hostile tumor microenvironments, a lack of tumor-specific target antigens, and the high cost and poor scalability of cell therapy manufacturing. Creative genome-editing strategies are beginning to emerge to address each of these limitations, which has initiated the next generation of cell therapy products now entering clinical trials. CRISPR is at the forefront of this revolution, offering a simple and versatile platform for genetic engineering. This review provides a comprehensive overview of CRISPR applications that have advanced ACT. SIGNIFICANCE: The clinical impact of ACT for cancer can be expanded by implementing specific genetic modifications that enhance the potency, safety, and scalability of cellular products. Here we provide a detailed description of such genetic modifications, highlighting avenues to enhance the therapeutic efficacy and accessibility of ACT for cancer. Furthermore, we review high-throughput CRISPR genetic screens that have unveiled novel targets for cell therapy enhancement.

Revving the CAR - Combination strategies to enhance CAR T cell effectiveness.

Chimeric antigen receptor (CAR) T cell therapy is currently approved for treatment of refractory B-cell malignancies. Response rates in these diseases are impressive by historical standards, but most patients do not have a durable response and there remains room for improvement. To date, CAR T cell activity has been even more limited in solid malignancies. These limitations are thought to be due to several pathways of resistance to CAR T cells, including cell-intrinsic mechanisms and the immunosuppressive tumor microenvironment. In this review, we discuss current experimental strategies that combine small molecules and monoclonal antibodies with CAR T cells to overcome these resistance mechanisms. We describe the biological rationale, pre-clinical data and clinical trials in progress that test the efficacy and safety of these combinations.

Anti-PD-1/PD-L1 Blockade Immunotherapy Employed in Treating Hepatitis B Virus Infection-Related Advanced Hepatocellular Carcinoma: A Literature Review.

Hepatitis B virus (HBV) infection is regarded as the main etiological risk factor in the process of hepatocellular carcinoma (HCC), as it promotes an immunosuppressive microenvironment that is partially mediated by the programmed cell death protein 1 (PD-1)/programmed death-ligand 1 (PD-L1) signaling pathway. The tumor microenvironment (TME) of HBV-related HCC is indeed more immunosuppressive than microenvironments not associated with viruses. And compared to TME in hepatitis C virus (HCV) infected HCC, TME of HBV-related HCC is less vascularized and presents different immune components resulting in similar immunosuppression. However, few studies are focusing on the specific side effects and efficacy of PD-1/PD-L1 blockade immunotherapy in HBV-related HCC patients, as well as on the underlying mechanism. Herein, we reviewed the basic research focusing on potential TME alteration caused by HBV infection, especially in HCC patients. Moreover, we reviewed PD-1/PD-L1 blockade immunotherapy clinical trials to clarify the safety and efficacy of this newly developed treatment in the particular circumstances of HBV infection. We found that patients with HBV-related HCC displayed an acceptable safety profile similar to those of non-infected HCC patients. However, we could not determine the antiviral activity of PD-1/PD-L1 blockade because standard anti-viral therapies were conducted in all of the current clinical trials, which made it difficult to distinguish the potential influence of PD-1/PD-L1 blockade on HBV infection. Generally, the objective response rates (ORRs) of PD-1/PD-L1 blockade immunotherapy did not differ significantly between virus-positive and virus-negative patients, except that disease control rates (DCRs) were obviously lower in HBV-infected HCC patients.

Characterization of T-Cell Receptor Repertoire in Patients with Rheumatoid Arthritis Receiving Biologic Therapies.

Rheumatoid arthritis (RA) is a systematic autoimmune disease, predominantly causing chronic polyarticular inflammation and joint injury of patients. For the treatment of RA, biologic disease-modifying antirheumatic drugs (bDMARDs) have been used to reduce inflammation and to interfere with disease progression through targeting and mediating the immune system. Although the therapeutic effects of bDMARDs in RA patients have been widely reported, whether these drugs also play important roles in T-cell repertoire status is still unclear. We therefore designed the study to identify the role of T-cell repertoire profiles in RA patients with different types of bDMARD treatments. A high-throughput sequencing approach was applied to profile the T-cell receptor beta chain (TCRB) repertoire of circulating T lymphocytes in eight patients given adalimumab (anti-TNF-α) with/without the following use of either rituximab (anti-CD20) or tocilizumab (anti-IL6R). We subsequently analyzed discrepancies in the clonal diversity and CDR3 length distribution as well as usages of the V and J genes of TCRB repertoire and interrogated the association between repertoire diversity and disease activities followed by the treatment of bDMARDs in these RA patients. All groups of patients showed well-controlled DAS28 scores (<2.6) after different treatment regimens of drugs and displayed no significant statistical differences in repertoire diversity, distribution of CDR3 lengths, and usage of V and J genes of TCRB. Nonetheless, a trend between overall TCRB repertoire diversity and disease activity scores in all bDMARD-treated RA patients was observed. Additionally, age was found to be associated with repertoire diversity in RA patients treated with bDMARDs. Through the profiling of the TCR repertoire in RA patients receiving different biologic medications, our study indicated an inverse tendency between TCR repertoire diversity and disease activity after biologic treatment in RA patients.

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.

Preclinical Evaluation of Chimeric Antigen Receptor-Modified T Cells Specific to Epithelial Cell Adhesion Molecule for Treating Colorectal Cancer.

Chimeric antigen receptor-modified T cells (CAR-T cells) have emerged as a promising cancer immunotherapy for solid tumors. Epithelial cell adhesion molecule (EpCAM) is overexpressed in a variety of tumors and is recognized as a biomarker for circulating tumor cells and cancer stem cells, representing an attractive target for adoptive T-cell immunotherapy. This study generated third-generation CAR-T cells with redirected specificity to EpCAM (EpCAM CAR-T) by lentiviral vector. The study demonstrated that EpCAM CAR-T cells can elicit lytic cytotoxicity to target cells in an EpCAM-dependent manner and secrete cytotoxic cytokines, including interferon gamma and tumor necrosis factor alpha. Furthermore, adoptive transfer of EpCAM CAR-T cells significantly delayed tumor growth and formation in xenograft models. In addition, the safety evaluation showed that CAR-T cells have no systemic toxicity in mice. The data confirmed the antitumor ability and safety of CAR-T cells targeting EpCAM and may provide a new target for CAR-T cell therapies in treating solid tumors.

Transcription factor YY1 is essential for iNKT cell development.

Invariant natural killer T (iNKT) cells develop from CD4+CD8+ double-positive (DP) thymocytes and express an invariant Vα14-Jα18 T-cell receptor (TCR) α-chain. Generation of these cells requires the prolonged survival of DP thymocytes to allow for Vα14-Jα18 gene rearrangements and strong TCR signaling to induce the expression of the iNKT lineage-specific transcription factor PLZF. Here, we report that the transcription factor Yin Yang 1 (YY1) is essential for iNKT cell formation. Thymocytes lacking YY1 displayed a block in iNKT cell development at the earliest progenitor stage. YY1-deficient thymocytes underwent normal Vα14-Jα18 gene rearrangements, but exhibited impaired cell survival. Deletion of the apoptotic protein BIM failed to rescue the defect in iNKT cell generation. Chromatin immunoprecipitation and deep-sequencing experiments demonstrated that YY1 directly binds and activates the promoter of the Plzf gene. Thus, YY1 plays essential roles in iNKT cell development by coordinately regulating cell survival and PLZF expression.

NKT cells - New players in CAR cell immunotherapy?

Low levels of peripheral blood natural killer T (NKT) cells in cancer patients and a favorable outcome associated with a high number of tumor-infiltrating NKT cells demonstrated in several studies indicated the important role of these immune cells in the antitumor response. With effective antitumor immunity via direct tumor lysis, cytokine modulation of effector cells and regulation of immunosuppressive cells, type I NKT cells display interesting features/properties for the rapidly developing chimeric antigen receptor (CAR) technology. Due to their restriction to the monomorphic HLA-like molecule CD1d, but not to the polymorphic human leukocyte antigen (HLA), NKT CAR cells show potential for enabling autologous and allogeneic/off-the-shelf cancer immunotherapy. Promising results were obtained in preclinical NKT CAR cell studies, but clinical trials have not yet been conducted. In this review, we summarize the biological features of NKT cells, their role in antitumor immunity and recent advances in the development of NKT CAR cells.

Chimeric Antigen Receptor T Cells: Extending Translation from Liquid to Solid Tumors.

Successful translation of chimeric antigen receptor (CAR) T cells designed to target and eradicate CD19+ lymphomas has emboldened scientists and physicians worldwide to explore the possibility of applying CAR T-cell technology to other tumor entities, including solid tumors. Next-generation strategies such as fourth-generation CARs (CAR T cells redirected for universal cytokine killing, also known as TRUCKs) designed to deliver immunomodulatory cytokines to the tumor microenvironment, dual CAR designs to improve tumor control, inclusion of suicide genes as safety switches, and precision genome editing are currently being investigated. One major ongoing goal is to determine how best to generate CAR T cells that modulate the tumor microenvironment, overcome tumor survival mechanisms, and thus allow broader applicability as universal allogeneic T-cell therapeutics. Development of state-of-the-art and beyond viral vector systems to deliver designer CARs coupled with targeted genome editing is expected to generate more effective off-the-shelf CAR T cells with activity against a greater number of cancer types and importantly solid tumors.

Protein tyrosine phosphatase PTPN22 regulates LFA-1 dependent Th1 responses.

A missense C1858T single nucleotide polymorphism within PTPN22 is a strong genetic risk factor for the development of multiple autoimmune diseases. PTPN22 encodes a protein tyrosine phosphatase that negatively regulates immuno-receptor proximal Src and Syk family kinases. Notably, PTPN22 negatively regulates kinases downstream of T-cell receptor (TCR) and LFA-1, thereby setting thresholds for T-cell activation. Alterations to the quality of TCR and LFA-1 engagement at the immune synapse and the regulation of downstream signals can have profound effects on the type of effector T-cell response induced. Here we describe how IFNγ+ Th1 responses are potentiated in Ptpn22-/- T-cells and in T-cells from mice expressing Ptpn22R619W (the mouse orthologue of the human genetic variant) as they age, or following repeated immune challenge, and explore the mechanisms contributing to the expansion of Th1 cells. Specifically, we uncover two LFA-1-ICAM dependent mechanisms; one T-cell intrinsic, and one T-cell extrinsic. Firstly, we found that in vitro anti-CD3/LFA-1 induced Th1 responses were enhanced in Ptpn22-/- T-cells compared to WT, whereas anti-CD3/anti-CD28 induced IFNy responses were similar. These data were associated with an enhanced ability of Ptpn22-/- T-cells to engage ICAM-1 at the immune synapse when incubated on planar lipid bilayers, and to form conjugates with dendritic cells. Secondly, we observed a T-cell extrinsic mechanism whereby repeated stimulation of WT OT-II T-cells with LPS and OVA323-339 pulsed Ptpn22-/- bone marrow derived dendritic cells (BMDCs) was sufficient to enhance Th1 cell development compared to WT BMDCs. Furthermore, this response could be reversed by LFA-1 blockade. Our data point to two related but distinct mechanisms by which PTPN22 regulates LFA-1 dependent signals to enhance Th1 development, highlighting how perturbations to PTPN22 function over time to regulate the balance of the immune response.

Influence of Retronectin-Mediated T-Cell Activation on Expansion and Phenotype of CD19-Specific Chimeric Antigen Receptor T Cells.

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.

Anti-CD123 chimeric antigen receptor T-cells (CART): an evolving treatment strategy for hematological malignancies, and a potential ace-in-the-hole against antigen-negative relapse.

Chimeric antigen receptor-modified T-cells (CART) are a potent and targeted immunotherapy which have induced remissions in some patients with chemotherapy refractory or relapsed (RR) hematologic malignancies. Hundreds of patients have now been treated worldwide with anti-CD19 CART cells, with complete response rates of up to 90%. CART therapy has a unique toxicity profile, and unfortunately not all responses are durable. Treatment failure occurs via two main routes - by loss of the CART cell population, or relapse with antigen loss. Emerging data indicate that targeting an alternative antigen instead of, or as well as CD19, could improve CART cell efficacy and reduce antigen-negative relapse. Other strategies include the addition of other immune-based therapies. This review explores the rationale, pre-clinical data and currently investigative strategies underway for CART therapy targeting the myeloid and lymphoid stem/progenitor antigen CD123.

Novel and shared neoantigen derived from histone 3 variant H3.3K27M mutation for glioma T cell therapy.

The median overall survival for children with diffuse intrinsic pontine glioma (DIPG) is less than one year. The majority of diffuse midline gliomas, including more than 70% of DIPGs, harbor an amino acid substitution from lysine (K) to methionine (M) at position 27 of histone 3 variant 3 (H3.3). From a CD8+ T cell clone established by stimulation of HLA-A2+ CD8+ T cells with synthetic peptide encompassing the H3.3K27M mutation, complementary DNA for T cell receptor (TCR) α- and ß-chains were cloned into a retroviral vector. TCR-transduced HLA-A2+ T cells efficiently killed HLA-A2+H3.3K27M+ glioma cells in an antigen- and HLA-specific manner. Adoptive transfer of TCR-transduced T cells significantly suppressed the progression of glioma xenografts in mice. Alanine-scanning assays suggested the absence of known human proteins sharing the key amino acid residues required for recognition by the TCR, suggesting that the TCR could be safely used in patients. These data provide us with a strong basis for developing T cell-based therapy targeting this shared neoepitope.

Preclinical Optimization of a CD20-specific Chimeric Antigen Receptor Vector and Culture Conditions.

Chimeric antigen receptor (CAR)-based adoptive T-cell therapy is a highly promising treatment for lymphoid malignancies, and CD20 is an ideal target antigen. We previously developed a lentiviral construct encoding a third generation CD20-targeted CAR but identified several features that required additional optimization before clinical translation. We describe here several improvements, including replacement of the immunogenic murine antigen-binding moiety with a fully human domain, streamlining the transgene insert to enhance lentiviral titers, modifications to the extracellular IgG spacer that abrogate nonspecific activation resulting from binding to Fc receptors, and evaluation of CD28, 4-1BB, or CD28 and 4-1BB costimulatory domains. We also found that restimulation of CAR T cells with an irradiated CD20 cell line boosted cell growth, increased the fraction of CAR-expressing cells, and preserved in vivo function despite leading to a reduced capacity for cytokine secretion in vitro. We also found that cryopreservation of CAR T cells did not affect immunophenotype or in vivo antitumor activity compared with fresh cells. These optimization steps resulted in significant improvement in antitumor activity in mouse models, resulting in eradication of established systemic lymphoma tumors in 75% of mice with a single infusion of CAR T cells, and prolonged in vivo persistence of modified cells. These results provide the basis for clinical testing of a lentiviral construct encoding a fully human CD20-targeted CAR with CD28 and 4-1BB costimulatory domains and truncated CD19 (tCD19) transduction marker.