Armored TGFßRIIDN ROR1-CAR T cells reject solid tumors and resist suppression by constitutively-expressed and treatment-induced TGFß1.

BACKGROUND: Chimeric antigen receptor (CAR) T-cell therapy target receptor tyrosine kinase-like orphan receptor 1 (ROR1) is broadly expressed in hematologic and solid tumors, however clinically-characterized ROR1-CAR T cells with single chain variable fragment (scFv)-R12 targeting domain failed to induce durable remissions, in part due to the immunosuppressive tumor microenvironment (TME). Herein, we describe the development of an improved ROR1-CAR with a novel, fully human scFv9 targeting domain, and augmented with TGFßRIIDN armor protective against a major TME factor, transforming growth factor beta (TGFß). METHODS: CAR T cells were generated by lentiviral transduction of enriched CD4+ and CD8+ T cells, and the novel scFv9-based ROR1-CAR-1 was compared with the clinically-characterized ROR1-R12-scFv-based CAR-2 in vitro and in vivo. RESULTS: CAR-1 T cells exhibited greater CAR surface density than CAR-2 when normalized for %CAR+, and produced more interferon (IFN)-γ tumor necrosis factor (TNF)-α and interleukin (IL)-2 in response to hematologic (Jeko-1, RPMI-8226) and solid (OVCAR-3, Capan-2, NCI-H226) tumor cell lines in vitro. In vivo, CAR-1 and CAR-2 both cleared hematologic Jeko-1 lymphoma xenografts, however only CAR-1 fully rejected ovarian solid OVCAR-3 tumors, concordantly with greater expansion of CD8+ and CD4+CAR T cells, and enrichment for central and effector memory phenotype. When equipped with TGFß-protective armor TGFßRIIDN, CAR-1 T cells resisted TGFß-mediated pSmad2/3 phosphorylation, as compared with CAR-1 alone. When co-cultured with ROR-1+ AsPC-1 pancreatic cancer line in the presence of TGFß1, armored CAR-1 demonstrated improved recovery of killing function, IFN-γ, TNF-α and IL-2 secretion. In mouse AsPC-1 pancreatic tumor xenografts overexpressing TGFß1, armored CAR-1, in contrast to CAR-1 alone, achieved complete tumor remissions, and yielded accelerated expansion of CAR+ T cells, diminished circulating active TGFß1, and no apparent toxicity or weight loss. Unexpectedly, in AsPC-1 xenografts without TGFß overexpression, TGFß1 production was specifically induced by ROR-1-CAR T cells interaction with ROR-1 positive tumor cells, and the TGFßRIIDN armor conferred accelerated tumor clearance. CONCLUSIONS: The novel fully human TGFßRIIDN-armored ROR1-CAR-1 T cells are highly potent against ROR1-positive tumors, and withstand the inhibitory effects of TGFß in solid TME. Moreover, TGFß1 induction represents a novel, CAR-induced checkpoint in the solid TME, which can be circumvented by co-expressing the TGßRIIDN armor on T cells.

Allogeneic CD19/CD22 CAR T-Cell Therapy for B-Cell Acute Lymphoblastic Leukemia.

This case series reports durable remissions in 2 patients with relapsed/refractory B-cell acute lymphoblastic leukemia treated with allogeneic bispecific CD19/CD22-targeting chimeric antigen receptor T cells.

Preclinical development of a chimeric antigen receptor T cell therapy targeting FGFR4 in rhabdomyosarcoma.

Pediatric patients with relapsed or refractory rhabdomyosarcoma (RMS) have dismal cure rates, and effective therapy is urgently needed. The oncogenic receptor tyrosine kinase fibroblast growth factor receptor 4 (FGFR4) is highly expressed in RMS and lowly expressed in healthy tissues. Here, we describe a second-generation FGFR4-targeting chimeric antigen receptor (CAR), based on an anti-human FGFR4-specific murine monoclonal antibody 3A11, as an adoptive T cell treatment for RMS. The 3A11 CAR T cells induced robust cytokine production and cytotoxicity against RMS cell lines in vitro. In contrast, a panel of healthy human primary cells failed to activate 3A11 CAR T cells, confirming the selectivity of 3A11 CAR T cells against tumors with high FGFR4 expression. Finally, we demonstrate that 3A11 CAR T cells are persistent in vivo and can effectively eliminate RMS tumors in two metastatic and two orthotopic models. Therefore, our study credentials CAR T cell therapy targeting FGFR4 to treat patients with RMS.

CD19/22 CAR T cells in children and young adults with B-ALL: phase 1 results and development of a novel bicistronic CAR.

Remission durability following single-antigen targeted chimeric antigen receptor (CAR) T-cells is limited by antigen modulation, which may be overcome with combinatorial targeting. Building upon our experiences targeting CD19 and CD22 in B-cell acute lymphoblastic leukemia (B-ALL), we report on our phase 1 dose-escalation study of a novel murine stem cell virus (MSCV)-CD19/CD22-4-1BB bivalent CAR T-cell (CD19.22.BBζ) for children and young adults (CAYA) with B-cell malignancies. Primary objectives included toxicity and dose finding. Secondary objectives included response rates and relapse-free survival (RFS). Biologic correlatives included laboratory investigations, CAR T-cell expansion and cytokine profiling. Twenty patients, ages 5.4 to 34.6 years, with B-ALL received CD19.22.BBζ. The complete response (CR) rate was 60% (12 of 20) in the full cohort and 71.4% (10 of 14) in CAR-naïve patients. Ten (50%) developed cytokine release syndrome (CRS), with 3 (15%) having ≥ grade 3 CRS and only 1 experiencing neurotoxicity (grade 3). The 6- and 12-month RFS in those achieving CR was 80.8% (95% confidence interval [CI]: 42.4%-94.9%) and 57.7% (95% CI: 22.1%-81.9%), respectively. Limited CAR T-cell expansion and persistence of MSCV-CD19.22.BBζ compared with EF1α-CD22.BBζ prompted laboratory investigations comparing EF1α vs MSCV promoters, which did not reveal major differences. Limited CD22 targeting with CD19.22.BBζ, as evaluated by ex vivo cytokine secretion and leukemia eradication in humanized mice, led to development of a novel bicistronic CD19.28ζ/CD22.BBζ construct with enhanced cytokine production against CD22. With demonstrated safety and efficacy of CD19.22.BBζ in a heavily pretreated CAYA B-ALL cohort, further optimization of combinatorial antigen targeting serves to overcome identified limitations (www.clinicaltrials.gov #NCT03448393).

Patient-reported outcomes and neurotoxicity markers in patients treated with bispecific LV20.19 CAR T cell therapy.

Background: With the rising number of chimeric antigen receptor (CAR) T cell treated patients, it is increasingly important to understand the treatment's impact on patient-reported outcomes (PROs) and, ideally, identify biomarkers of central nervous system (CNS) adverse effects. Methods: The purpose of this exploratory study was to assess short-term PROs and serum kynurenine metabolites for associated neurotoxicity among patients treated in an anti-CD20, anti-CD19 (LV20.19) CAR T cell phase I clinical trial (NCT03019055). Fifteen CAR T treated patients from the parent trial provided serum samples and self-report surveys 15 days before and 14, 28, and 90 days after treatment. Results: Blood kynurenine concentrations increased over time in patients with evidence of neurotoxicity (p = 0.004) and were increased in self-reported depression (r = 0.52, p = 0.002). Depression improved after CAR T infusion (p = 0.035). Elevated 3-hydroxyanthranilic acid (3HAA) concentrations prior to cell infusion were also predictive of neurotoxicity onset (p = 0.031), suggesting it is a biomarker of neurotoxicity following CAR T cell therapy. Conclusions: Elevated levels of kynurenine pathway metabolites among CAR T cell recipients are associated with depressed mood and neurotoxicity. Findings from this exploratory study are preliminary and warrant validation in a larger cohort.

This study examined the impact of chimeric antigen receptor (CAR) T cell therapy­a therapy that gets immune cells to fight cancer by changing them in the lab to find and destroy cancer cells­on blood markers associated with depression, anxiety, pain, fatigue, and poor sleep. Fifteen CAR T cell patients provided blood samples and completed surveys before and three timepoints after treatment. We found that the amount of kynurenine, a normal blood constituent, and related molecules was higher in patients who experienced significant CAR T cell side effects on the brain and in patients reporting more depression. These results identify the excessive elevation of blood constituents related to the mood that may also be associated with depression and brain dysfunction following CAR T. These blood constituents could potentially be used as markers and targeted with interventions to prevent brain dysfunction.

Bispecific targeting of CD20 and CD19 increases polyfunctionality of chimeric antigen receptor T-cell products in B-cell malignancies.

BACKGROUND AIMS: Selective immune pressure contributes to relapse due to target antigen downregulation in patients treated with anti-CD19 chimeric antigen receptor (CAR) T cells. Bispecific lentiviral anti-CD20/anti-CD19 (LV20.19) CAR T cells may prevent progression/relapse due to antigen escape. Highly polyfunctional T cells within a CAR T-cell product have been associated with response in single-antigen-targeted anti-CD19 CAR T cells. METHODS: The authors performed a single-cell proteomic analysis to assess polyfunctional cells in our LV20.19 CAR T-cell product. Analysis was limited to those treated at a fixed dose of 2.5 × 106 cells/kg (n = 16). Unused pre-infusion CAR T cells were thawed, sorted into CD4/CD8 subsets and stimulated with K562 cells transduced to express CD19 or CD20. Single-cell production of 32 individual analytes was measured and polyfunctionality and polyfunctional strength index (PSI) were calculated. RESULTS: Fifteen patients had adequate leftover cells for analysis upon stimulation with CD19, and nine patients had adequate leftover cells for analysis upon stimulation with CD20. For LV20.19 CAR T cells, PSI was 866-1109 and polyfunctionality was 40-45%, which were higher than previously reported values for other CAR T-cell products. CONCLUSIONS: Stimulation with either CD19 or CD20 antigens resulted in similar levels of analyte activation, suggesting that this product may have efficacy in CD19- patient populations.

Primary CD33-targeting CAR-NK cells for the treatment of acute myeloid leukemia.

Acute myeloid leukemia (AML) is a malignant disorder derived from neoplastic myeloid progenitor cells characterized by abnormal proliferation and differentiation. Although novel therapeutics have recently been introduced, AML remains a therapeutic challenge with insufficient cure rates. In the last years, immune-directed therapies such as chimeric antigen receptor (CAR)-T cells were introduced, which showed outstanding clinical activity against B-cell malignancies including acute lymphoblastic leukemia (ALL). However, the application of CAR-T cells appears to be challenging due to the enormous molecular heterogeneity of the disease and potential long-term suppression of hematopoiesis. Here we report on the generation of CD33-targeted CAR-modified natural killer (NK) cells by transduction of blood-derived primary NK cells using baboon envelope pseudotyped lentiviral vectors (BaEV-LVs). Transduced cells displayed stable CAR-expression, unimpeded proliferation, and increased cytotoxic activity against CD33-positive OCI-AML2 and primary AML cells in vitro. Furthermore, CD33-CAR-NK cells strongly reduced leukemic burden and prevented bone marrow engraftment of leukemic cells in OCI-AML2 xenograft mouse models without observable side effects.

Armored BCMA CAR T Cells Eliminate Multiple Myeloma and Are Resistant to the Suppressive Effects of TGF-ß.

CAR T-cell therapies targeting the B-cell maturation antigen eliminate tumors in relapsed/refractory multiple myeloma patients, however durable remissions remain difficult to attain. Transforming growth factor beta (TGF-ß) is a multifunctional cytokine abundantly expressed in the multiple myeloma bone marrow niche, where it promotes an immunosuppressive tumor microenvironment. We hypothesized that BCMA CAR T-cells armored to resist the suppressive effects of TGF-ß will provide an advantage in treating multiple myeloma. The armored B2ARM CAR T cells, co-expressing BCMA targeting CAR with TGF-ß dominant-negative receptor II, were generated by lentiviral transduction of primary human CD4+ and CD8+ T cells. The B2ARM CAR T cells eliminated MM.1S multiple myeloma targets in long-term cytotoxicity assays, even under TGF-ß-high conditions, whereas cytotoxic function of the non-armored B2 CAR -T cells was inhibited by TGF-ß. Concordantly, after long-term exposure to targets in the presence of TGF-ß, the B2ARM CAR T cells were enriched for Granzyme B, CD107a, Ki67 and polyfunctional cells T-cells (double or triple-positive for IFN-γ, IL-2 and/or TNF-α), as determined by flow cytometry. In addition, the B2ARM CAR T-cells, but not the conventional B2 CAR T-cells, resisted the TGF-ß-mediated suppression of activation (CD25), exhaustion (PD-1, LAG3), and differentiation to T effectors (CD45RA+ CD45RO-CD62L-). In NSG mice bearing RPMI-8226 tumors overexpressing TGF-ß, the B2ARM CAR mediated 100% tumor rejection and survival, superior infiltration of tumors on day 7 post CAR T treatment (%CD3+CAR+), and greater expression of IFN-γ, TNF-α, Ki67, Granzyme B, and PD-1, as compared to tumor-infiltrating non-armored B2 CAR T-cells. In NSG RPMI-8226 xenograft model in which tumors were additionally supplemented with TGF-ß injections on days -1 through 11 of CAR T treatment, the B2ARM CAR T cells rejected tumors faster than the non-armored B2 CARs, and showed greater numbers of CD3+ and CD3+CAR+, central memory (CD45RO+CD62L+) and effector memory (CD45RO+CD62L-) T cells in the peripheral blood 18 days after treatment. In summary, the armored B2ARM CAR T cells mediate superior persistence, proliferation, multi-functionality, effector differentiation and anti-tumor function in pre-clinical models of multiple myeloma, while abrogating TGF-ß-mediated suppression.

Multiple site place-of-care manufactured anti-CD19 CAR-T cells induce high remission rates in B-cell malignancy patients.

Chimeric antigen receptor (CAR) T cells targeting the CD19 antigen are effective in treating adults and children with B-cell malignancies. Place-of-care manufacturing may improve performance and accessibility by obviating the need to cryopreserve and transport cells to centralized facilities. Here we develop an anti-CD19 CAR (CAR19) comprised of the 4-1BB co-stimulatory and TNFRSF19 transmembrane domains, showing anti-tumor efficacy in an in vivo xenograft lymphoma model. CAR19 T cells are manufactured under current good manufacturing practices (cGMP) at two disparate clinical sites, Moscow (Russia) and Cleveland (USA). The CAR19 T-cells is used to treat patients with relapsed/refractory pediatric B-cell Acute Lymphocytic Leukemia (ALL; n = 31) or adult B-cell Lymphoma (NHL; n = 23) in two independently conducted phase I clinical trials with safety as the primary outcome (NCT03467256 and NCT03434769, respectively). Probability of measurable residual disease-negative remission was also a primary outcome in the ALL study. Secondary outcomes include complete remission (CR) rates, overall survival and median duration of response. CR rates are 89% (ALL) and 73% (NHL). After a median follow-up of 17 months, one-year survival rate of ALL complete responders is 79.2% (95%CI 64.5‒97.2%) and median duration of response is 10.2 months. For NHL complete responders one-year survival is 92.9%, and median duration of response has not been reached. Place-of-care manufacturing produces consistent CAR-T cell products at multiple sites that are effective for the treatment of patients with B-cell malignancies.

Titratable Pharmacological Regulation of CAR T Cells Using Zinc Finger-Based Transcription Factors.

Chimeric antigen receptor (CAR) T cell therapy has emerged as an attractive strategy for cancer immunotherapy. Despite remarkable success for hematological malignancies, excessive activity and poor control of CAR T cells can result in severe adverse events requiring control strategies to improve safety. This work illustrates the feasibility of a zinc finger-based inducible switch system for transcriptional regulation of an anti-CD20 CAR in primary T cells providing small molecule-inducible control over therapeutic functions. We demonstrate time- and dose-dependent induction of anti-CD20 CAR expression and function with metabolites of the clinically-approved drug tamoxifen, and the absence of background CAR activity in the non-induced state. Inducible CAR T cells executed fine-tuned cytolytic activity against target cells both in vitro and in vivo, whereas CAR-related functions were lost upon drug discontinuation. This zinc finger-based transcriptional control system can be extended to other therapeutically important CARs, thus paving the way for safer cellular therapies.

Self-driving armored CAR-T cells overcome a suppressive milieu and eradicate CD19+ Raji lymphoma in preclinical models.

Chimeric antigen receptor (CAR) T cells typically use a strong constitutive promoter to ensure maximal long-term CAR expression. However, recent evidence suggests that restricting the timing and magnitude of CAR expression is functionally beneficial, whereas constitutive CAR activation may lead to exhaustion and loss of function. We created a self-driving CD19-targeting CAR, which regulates its own function based on the presence of a CD19 antigen engaged by the CAR itself, by placing self-driving CAR19 constructs under transcriptional control of synthetic activator protein 1 (AP1)-nuclear factor κB (NF-κB) or signal transducer and activator of transcription (STAT)5 promoters. CD19 antigen-regulated expression was observed for self-driving AP1-NFκB-CAR19, with CAR19 upregulation within 18 h after exposure to target CD19, and corresponded to the level of tumor burden. Self-driving CAR-T cells showed enhanced tumor-dependent activation, expansion, and low exhaustion in vitro as compared to constitutively expressed EF1α and murine stem cell virus (MSCV) CARs and mediated tumor regression and survival in Raji-bearing NOD.Cg-PrkdcscidIl2rgtm1Wjl/SzJ (NSG) mice. Long-term CAR function correlated with upregulated CAR expression within 24 h of exposure to tumor antigen. The self-driving AP1-NFκB-CAR19 circuit was also used to inducibly express dominant-negative transforming growth factor ß receptor II (TGFBRIIdn), which effectively countered the negative effects of TGF-ß on CAR-T activation. Thus, a self-driving CAR approach may offer a new modality to express CAR and auxiliary proteins by enhancing CAR-T functional activity and limiting exhaustion.

Trispecific CD19-CD20-CD22-targeting duoCAR-T cells eliminate antigen-heterogeneous B cell tumors in preclinical models.

A substantial number of patients with leukemia and lymphoma treated with anti-CD19 or anti-CD22 monoCAR-T cell therapy relapse because of antigen loss or down-regulation. We hypothesized that B cell tumor antigen escape may be overcome by a chimeric antigen receptor (CAR) design that simultaneously targets three B cell leukemia antigens. We engineered trispecific duoCAR-T cells with lentiviral vectors encoding two CAR open reading frames that target CD19, CD20, and CD22. The duoCARs were composed of a CAR with a tandem CD19- and CD20-targeting binder, linked by the P2A self-cleaving peptide to a second CAR targeting CD22. Multiple combinations of intracellular T cell signaling motifs were evaluated. The most potent duoCAR architectures included those with ICOS, OX40, or CD27 signaling domains rather than those from CD28 or 4-1BB. We identified four optimal binder and signaling combinations that potently rejected xenografted leukemia and lymphoma tumors in vivo. Moreover, in mice bearing a mixture of B cell lymphoma lines composed of parental triple-positive cells, CD19-negative, CD20-negative, and CD22-negative variants, only the trispecific duoCAR-T cells rapidly and efficiently rejected the tumors. Each of the monoCAR-T cells failed to prevent tumor progression. Analysis of intracellular signaling profiles demonstrates that the distinct signaling of the intracellular domains used may contribute to these differential effects. Multispecific duoCAR-T cells are a promising strategy to prevent antigen loss-mediated relapse or the down-regulation of target antigen in patients with B cell malignancies.

Bispecific anti-CD20, anti-CD19 CAR T cells for relapsed B cell malignancies: a phase 1 dose escalation and expansion trial.

Chimeric antigen receptor (CAR) T cells targeting CD19 are a breakthrough treatment for relapsed, refractory B cell malignancies1-5. Despite impressive outcomes, relapse with CD19- disease remains a challenge. We address this limitation through a first-in-human trial of bispecific anti-CD20, anti-CD19 (LV20.19) CAR T cells for relapsed, refractory B cell malignancies. Adult patients with B cell non-Hodgkin lymphoma or chronic lymphocytic leukemia were treated on a phase 1 dose escalation and expansion trial (NCT03019055) to evaluate the safety of 4-1BB-CD3ζ LV20.19 CAR T cells and the feasibility of on-site manufacturing using the CliniMACS Prodigy system. CAR T cell doses ranged from 2.5 × 105-2.5 × 106 cells per kg. Cell manufacturing was set at 14 d with the goal of infusing non-cryopreserved LV20.19 CAR T cells. The target dose of LV20.19 CAR T cells was met in all CAR-naive patients, and 22 patients received LV20.19 CAR T cells on protocol. In the absence of dose-limiting toxicity, a dose of 2.5 × 106 cells per kg was chosen for expansion. Grade 3-4 cytokine release syndrome occurred in one (5%) patient, and grade 3-4 neurotoxicity occurred in three (14%) patients. Eighteen (82%) patients achieved an overall response at day 28, 14 (64%) had a complete response, and 4 (18%) had a partial response. The overall response rate to the dose of 2.5 × 106 cells per kg with non-cryopreserved infusion (n = 12) was 100% (complete response, 92%; partial response, 8%). Notably, loss of the CD19 antigen was not seen in patients who relapsed or experienced treatment failure. In conclusion, on-site manufacturing and infusion of non-cryopreserved LV20.19 CAR T cells were feasible and therapeutically safe, showing low toxicity and high efficacy. Bispecific CARs may improve clinical responses by mitigating target antigen downregulation as a mechanism of relapse.

Automated Manufacture of Autologous CD19 CAR-T Cells for Treatment of Non-hodgkin Lymphoma.

Chimeric antigen receptor T cells (CAR-T cell) targeting CD19 are effective against several subtypes of CD19-expressing hematologic malignancies. Centralized manufacturing has allowed rapid expansion of this cellular therapy, but it may be associated with treatment delays due to the required logistics. We hypothesized that point of care manufacturing of CAR-T cells on the automated CliniMACS Prodigy® device allows reproducible and fast delivery of cells for the treatment of patients with non-Hodgkin lymphoma. Here we describe cell manufacturing results and characterize the phenotype and effector function of CAR-T cells used in a phase I/II study. We utilized a lentiviral vector delivering a second-generation CD19 CAR construct with 4-1BB costimulatory domain and TNFRSF19 transmembrane domain. Our data highlight the successful generation of CAR-T cells at numbers sufficient for all patients treated, a shortened duration of production from 12 to 8 days followed by fresh infusion into patients, and the detection of CAR-T cells in patient circulation up to 1-year post-infusion.

Persistent Polyfunctional Chimeric Antigen Receptor T Cells That Target Glypican 3 Eliminate Orthotopic Hepatocellular Carcinomas in Mice.

BACKGROUND AND AIMS: Glypican 3 (GPC3) is an oncofetal antigen involved in Wnt-dependent cell proliferation that is highly expressed in hepatocellular carcinoma (HCC). We investigated whether the functions of chimeric antigen receptors (CARs) that target GPC3 are affected by their antibody-binding properties. METHODS: We collected peripheral blood mononuclear cells from healthy donors and patients with HCC and used them to create CAR T cells, based on the humanized YP7 (hYP7) and HN3 antibodies, which have high affinities for the C-lobe and N-lobe of GPC3, respectively. NOD/SCID/IL-2Rgcnull (NSG) mice were given intraperitoneal injections of luciferase-expressing (Luc) Hep3B or HepG2 cells and after xenograft tumors formed, mice were given injections of saline or untransduced T cells (mock control), or CAR (HN3) T cells or CAR (hYP7) T cells. In other NOD/SCID/IL-2Rgcnull (NSG) mice, HepG2-Luc or Hep3B-Luc cells were injected into liver, and after orthotopic tumors formed, mice were given 1 injection of CAR (hYP7) T cells or CD19 CAR T cells (control). We developed droplet digital polymerase chain reaction and genome sequencing methods to analyze persistent CAR T cells in mice. RESULTS: Injections of CAR (hYP7) T cells eliminated tumors in 66% of mice by week 3, whereas CAR (HN3) T cells did not reduce tumor burden. Mice given CAR (hYP7) T cells remained tumor free after re-challenge with additional Hep3B cells. The CAR T cells induced perforin- and granzyme-mediated apoptosis and reduced levels of active ß-catenin in HCC cells. Mice injected with CAR (hYP7) T cells had persistent expansion of T cells and subsets of polyfunctional CAR T cells via antigen-induced selection. These T cells were observed in the tumor microenvironment and spleen for up to 7 weeks after CAR T-cell administration. Integration sites in pre-infusion CAR (HN3) and CAR (hYP7) T cells were randomly distributed, whereas integration into NUPL1 was detected in 3.9% of CAR (hYP7) T cells 5 weeks after injection into tumor-bearing mice and 18.1% of CAR (hYP7) T cells at week 7. There was no common site of integration in CAR (HN3) or CD19 CAR T cells from tumor-bearing mice. CONCLUSIONS: In mice with xenograft or orthoptic liver tumors, CAR (hYP7) T cells eliminate GPC3-positive HCC cells, possibly by inducing perforin- and granzyme-mediated apoptosis or reducing Wnt signaling in tumor cells. GPC3-targeted CAR T cells might be developed for treatment of patients with HCC.

Corrigendum: A Distinct Subset of Highly Proliferative and Lentiviral Vector (LV)-Transducible NK Cells Define a Readily Engineered Subset for Adoptive Cellular Therapy.

[This corrects the article DOI: 10.3389/fimmu.2019.02001.].

A Distinct Subset of Highly Proliferative and Lentiviral Vector (LV)-Transducible NK Cells Define a Readily Engineered Subset for Adoptive Cellular Therapy.

Genetic engineering is an important tool for redirecting the function of various types of immune cells and their use for therapeutic purpose. Although NK cells have many beneficial therapeutic features, genetic engineering of immune cells for targeted therapy focuses mostly on T cells. One of the major obstacles for NK cell immunotherapy is the lack of an efficient method for gene transfer. Lentiviral vectors have been proven to be a safe tool for genetic engineering, however lentiviral transduction is inefficient for NK cells. We show in this study that lentiviral vectors pseudotyped with a modified baboon envelope glycoprotein can transduce NK cells 20-fold or higher in comparison to VSV-G pseudotyped lentiviral vector. When we investigated the mechanism of transduction, we found that activated NK cells expressed baboon envelope receptor ASCT-2. Further analysis revealed that only a subset of NK cells could be expanded and transduced with an expression profile of NK56bright, CD16dim, TRAILhigh, and CX3CR1neg. Using CD19-CAR, we could show that CD19 redirected NK cells efficiently and specifically kill cell lines expressing CD19. Taken together, the results from this study will be important for future genetic modification and for redirecting of NK cell function for therapeutic purpose.

Multispecific anti-HIV duoCAR-T cells display broad in vitro antiviral activity and potent in vivo elimination of HIV-infected cells in a humanized mouse model.

Adoptive immunotherapy using chimeric antigen receptor-modified T cells (CAR-T) has made substantial contributions to the treatment of certain B cell malignancies. Such treatment modalities could potentially obviate the need for long-term antiretroviral drug therapy in HIV/AIDS. Here, we report the development of HIV-1-based lentiviral vectors that encode CARs targeting multiple highly conserved sites on the HIV-1 envelope glycoprotein using a two-molecule CAR architecture, termed duoCAR. We show that transduction with lentiviral vectors encoding multispecific anti-HIV duoCARs confer primary T cells with the capacity to potently reduce cellular HIV infection by up to 99% in vitro and >97% in vivo. T cells are the targets of HIV infection, but the transduced T cells are protected from genetically diverse HIV-1 strains. The CAR-T cells also potently eliminated PBMCs infected with broadly neutralizing antibody-resistant HIV strains, including VRC01/3BNC117-resistant HIV-1. Furthermore, multispecific anti-HIV duoCAR-T cells demonstrated long-term control of HIV infection in vivo and prevented the loss of CD4+ T cells during HIV infection using a humanized NSG mouse model of intrasplenic HIV infection. These data suggest that multispecific anti-HIV duoCAR-T cells could be an effective approach for the treatment of patients with HIV-1 infection.

A Unique Human Immunoglobulin Heavy Chain Variable Domain-Only CD33 CAR for the Treatment of Acute Myeloid Leukemia.

Acute myeloid leukemia (AML) remains a challenging pediatric and adult disease. Given the elevated expression of the CD33 antigen on leukemic blasts, therapeutic approaches to AML now feature the approved antibody drug conjugate (Mylotarg, GO) and investigational CART cell approaches incorporating CD33-binding domains derived from humanized scFvs. We designed a functional chimeric antigen receptor utilizing a human targeting sequence, derived from a heavy chain variable domain, termed CAR33VH. Lentiviral-based expression vectors which encoded CAR constructs incorporating the novel binding domain (CAR33VH), or the My96 scFv control binder (My96CAR) in frame with a CD8 hinge and transmembrane domain, a 4-1BB costimulatory domain and a CD3 zeta activation domain, were transduced into primary human CD4+ and CD8+ T cells, and CAR expression was confirmed by flow cytometry. CAR33VH, similar to My96CAR, demonstrated robust and specific cytotoxicity in short-term and long-term co-incubation killing assays against CD33+ AML lines. In overnight cytokine release assays in which CAR T cells were challenged with the CD33+ tumor cells HL-60, MOLM-14 and KG-1a, CAR33VH elicited IFN-gamma, TNF-alpha and IL-2. This was seen with CD33+ cell lines, but not when CAR T were cultured alone. Studies with a CD33- cell line engineered to stably express the full length CD33 variant 1, or the naturally occurring CD33 splice variant 2, revealed that both CAR33VH and My96CAR, target the V domain of CD33, suggesting a similar therapeutic profile. Colony-formation assays utilizing peripheral blood CD34+ hematopoietic stem cells treated with CAR33VH, My96CAR, or with an untransduced T cell control, yielded similar numbers of BFU-E erythroid and CFU-GM myeloid colonies, suggesting a lack of CAR-related overt toxicity. In an in vivo AML model, NSG mice engrafted with MOLM-14 cells stably expressing firefly luciferase, both CAR33VH and CARMy96 efficiently eliminated tumors. In conclusion, we demonstrate for the first time the feasibility and efficacy of employing human variable domain-only binder derived from a phage display library in an anti-AML CAR design. CAR33VH, comprised of a human heavy-chain variable fragment-only antigen binding domain, was efficient in tumor killing in vitro and in vivo, and showed comparable functionality to the scFv-based My96CAR.

AIBP augments cholesterol efflux from alveolar macrophages to surfactant and reduces acute lung inflammation.

Acute respiratory distress syndrome (ARDS) is characterized by an excessive pulmonary inflammatory response. Removal of excess cholesterol from the plasma membrane of inflammatory cells helps reduce their activation. The secreted apolipoprotein A-I binding protein (AIBP) has been shown to augment cholesterol efflux from endothelial cells to the plasma lipoprotein HDL. Here, we find that AIBP was expressed in inflammatory cells in the human lung and was secreted into the bronchoalveolar space in mice subjected to inhalation of LPS. AIBP bound surfactant protein B and increased cholesterol efflux from alveolar macrophages to calfactant, a therapeutic surfactant formulation. In vitro, AIBP in the presence of surfactant reduced LPS-induced p65, ERK1/2 and p38 phosphorylation, and IL-6 secretion by alveolar macrophages. In vivo, inhalation of AIBP significantly reduced LPS-induced airspace neutrophilia, alveolar capillary leak, and secretion of IL-6. These results suggest that, similar to HDL in plasma, surfactant serves as a cholesterol acceptor in the lung. Furthermore, lung injury increases pulmonary AIBP expression, which likely serves to promote cholesterol efflux to surfactant and reduce inflammation.