Non-viral vectors for chimeric antigen receptor immunotherapy

B-cell maturation antigen chimeric antigen receptor T-cell re-expansion in a patient with myeloma following salvage programmed cell death protein 1 inhibitor-based combination therapy.

Chimeric antigen receptor (CAR) T-cell therapy has been shown to produce profound results in the treatment of certain hematologic malignancies, however treatment of solid tumors with CAR T cells has not been as successful. Studies have suggested that T-cell exhaustion plays a role in limiting the ability of CAR T cells to eradicate solid tumors. Additionally, stem-like qualities of T cells have been associated with better outcomes in patients treated with cellular therapies, including CAR T cells. Therefore, maintaining stem-like qualities and overcoming T-cell exhaustion may be key to improving clinical efficacy of CAR T cells in patients with solid tumors. ROR1 is a cell surface antigen expressed in several solid tumor types and chronic lymphocytic leukemia (CLL). ROR1 expression has been reported in 57% of triple-negative breast cancer (TNBC), as well as 42% of adenocarcinoma and 12% of squamous cell carcinoma subtypes of non-small cell lung cancer (NSCLC). These expression data of ROR1 in TNBC and NSCLC provide support for anti-ROR1 agents as a therapeutic strategy for these cancers. LYL797 is a novel, ROR1-targeted chimeric antigen receptor (CAR) T-cell product that incorporates genetic and epigenetic reprogramming technologies, Gen-R and Epi-R, to overcome barriers of CAR T-cell therapies in solid tumors. The ROR1-specific CAR contains a single-chain variable fragment (scFv) derived from an R12 rabbit monoclonal antibody that recognizes and binds with high specificity to human ROR1. Gen-R is ex vivo genetic reprogramming technology that engineers CAR T cells to overexpress c-Jun. Dysregulation of activator protein 1 (AP-1) has been implicated in CAR T-cell exhaustion, and studies have demonstrated that overexpression of c-Jun renders CAR T cells less susceptible to exhaustion, enhancing both anti-tumor efficacy and persistence in preclinical models of hematologic and solid tumors. Epi-R is a proprietary optimized manufacturing process that results in maintenance of stem-like phenotype and function of T-cell products. In preclinical studies LYL797 cells reprogrammed with Gen-R and Epi-R led to improved functional activity in the presence of ROR1+ tumor cells compared to conventional ROR1 CAR T cells. Additional studies are underway to determine the mechanisms by which antitumor activity of LYL797 in ROR1-positive solid tumor xenograft models is enhanced. LYL797 is anticipated to enter into Phase 1 clinical trials for TNBC and NSCLC in 2022. Citation Format: Spencer Park, Courtney Simianer, Sydney Spadinger, Xiao Wang, Purnima Sundar, Shobha Potluri, Rachel Lynn, Bijan Boldajipour, Grace Wang, Neeraj Sharma, Hajime Hiraragi, Veena Krishnamoorthy, Suman Kumar Vodnala, E-Ching Ong, Chang-Chih Wu, Martin Wohlfahrt, Byoung Ryu, Lisa Song, Brian D. Weitzner, Howell Moffett, Marc Lajoie, Scott Boyken, Tamer Shabaneh, Shivani Srivastava, Tina Albertson, Blythe Sather. LYL797, a ROR1 CAR T-cell therapy with genetic and epigenetic reprogramming for solid tumors [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 2754.

Chimeric antigen receptor (CAR) T-cell therapy has shown remarkable efficacy in cancer treatment. Nevertheless, most patients receiving CAR T cells relapse within 5 years of treatment. CAR-mediated trogocytosis (CMT) is a potential tumor escape mechanism in which cell surface proteins transfer from tumor cells to CAR T cells. CMT results in the emergence of antigen-negative tumor cells, which can evade future CAR detection, and antigen-positive CAR T cells, which have been suggested to cause CAR T-cell fratricide and exhaustion. Whether CMT indeed causes CAR T-cell dysfunction and the molecular mechanisms conferring CMT remain unknown. Using a selective degrader of trogocytosed antigen in CAR T cells, we show that the presence of trogocytosed antigen on the CAR T-cell surface directly causes CAR T-cell fratricide and exhaustion. By performing small molecule screening using a custom high-throughput CMT screening assay, we found that the cysteine protease cathepsin B is essential for CMT and that inhibition of cathepsin B is sufficient to prevent CAR T-cell fratricide and exhaustion, leading to improved long-term in vitro and in vivo CAR T-cell persistence and in vitro antitumor activity. Our data demonstrate that it is feasible to separate CMT from cytotoxic activity, that CAR T-cell persistence, a key factor associated with clinical CAR T-cell efficacy, is directly linked to cathepsin B activity in CAR T cells, and that it is possible to improve CAR T-cell function through selective inhibition of CMT.

Fetal bovine serum (FBS) or human serum is widely used in the production of chimeric antigen receptor (CAR) T-cells. In order to overcome a lot-to-lot inconsistency, the use of chemically defined medium that is free of animal-components would be highly desirable. The present study compared three serum-free media [Prime-XV™ T Cell CDM, Fujifilm™ (FF), LymphoONE™ T-Cell Expansion Xeno-Free Medium, Takara Bio™ (TB) and TCM GMP-Prototype, CellGenix™ (CG)] to the standard CAR T-cell medium containing FBS (RCF). After 12 days of CD19.CAR T-cell culture, the expansion, viability, transduction efficiency and phenotype were assessed using flow cytometry. The functionality of CAR T-cells was evaluated using intracellular staining, a chromium release assay and a long-term co-culture assay. Expansion and viability did not differ between the CAR T-cells generated in serum-free media compared to the standard FBS-containing medium. The CG CAR T-cells had a statistically significant higher frequency of IFNγ+ and IFNγ+TNF-α+ CAR T-cells than the CAR T-cells cultured with FBS (22.5 vs. 7.6%, P=0.0194; 15.3 vs. 6.2%, P=0.0399, respectively) as detected by intracellular cytokine staining. The CAR T-cells generated with serum-free media exhibited a higher cytotoxicity than the CAR T-cells cultured with FBS in the evaluation by chromium release assay [CG vs. RCF (P=0.0182), FF vs. RCF (P=0.0482) and TB vs. RCF (P=0.0482)]. Phenotyping on day 12 of CAR T-cell production did not reveal a significant difference in the expression of the exhaustion markers, programmed cell death protein 1, lymphocyte-activation gene 3 and T-cell immunoglobulin and mucin-domain containing-3. The CAR T-cells cultured in FF had a higher percentage of central memory CAR T-cells (40.0 vs. 14.3%, P=0.0470) than the CAR T-cells cultured with FBS, whereas the CAR T-cells in FF (6.2 vs. 24.2%, P=0.0029) and CG (11.0% vs. 24.2%, P=0.0468) had a lower frequency of naïve CAR T-cells. On the whole, the present study demonstrates that in general, the functionality and expansion of CAR T cells are maintained in serum-free media. Given the advantages of freedom from bovine material and consistent quality, serum-free media hold promise for the future development of the field of GMP manufacturing of CAR T-cells.

Immune response to three doses of mRNA SARS-CoV-2 vaccines in CD19-targeted chimeric antigen receptor Tcell immunotherapy recipients.

CRG-023 Is a Novel Tri-Specific CAR T Product Candidate Engineered to Prevent Antigen Escape and Sustain Durable Anti-Tumor Functionality Against B-Cell Malignancies

Identification of Two CAR T-Cell Populations Associated with Complete Response or Progressive Disease in Adult Lymphoma Patients Treated with Axi-Cel

Allogeneic CD34-Selected HSCT Following CAR T-Cells Is Associated with Low TRM and Favorable OS in Pediatric/Young Adult Patients with Relapsed/Refractory B-ALL

CD84: A Novel Target for CAR T-Cell Therapy for Acute Myeloid Leukemia

Antibiotic Therapy and Low Gut Microbiome Diversity Is Associated with Decreased Response and High Toxicity in BCP-ALL and DLBCL Patients after Treatment with CD19. CAR T-Cells

BackgroundPatients with relapsed/refractory osteosarcoma (OS) have dismal outcomes, and there are no systemic therapies that provide a survival benefit. Chimeric antigen receptor (CAR) T-cell immunotherapy involves the adoptive transfer of...

<div>Abstract<p>Chimeric antigen receptor (CAR) T-cell immunotherapy has revolutionized the treatment of refractory leukemias and lymphomas, but is associated with significant toxicities, namely cytokine release syndrome (CRS) and neurotoxicity. A major barrier to developing therapeutics to prevent CAR T cell–mediated neurotoxicity is the lack of clinically relevant models. Accordingly, we developed a rhesus macaque (RM) model of neurotoxicity via adoptive transfer of autologous CD20-specific CAR T cells. Following cyclophosphamide lymphodepletion, CD20 CAR T cells expand to 272 to 4,450 cells/μL after 7 to 8 days and elicit CRS and neurotoxicity. Toxicities are associated with elevated serum IL6, IL8, IL1RA, MIG, and I-TAC levels, and disproportionately high cerebrospinal fluid (CSF) IL6, IL2, GM-CSF, and VEGF levels. During neurotoxicity, both CD20 CAR and non-CAR T cells accumulate in the CSF and in the brain parenchyma. This RM model demonstrates that CAR T cell–mediated neurotoxicity is associated with proinflammatory CSF cytokines and a pan–T cell encephalitis.</p><p><b>Significance:</b> We provide the first immunologically relevant, nonhuman primate model of B cell–directed CAR T-cell therapy–mediated CRS and neurotoxicity. We demonstrate CAR and non-CAR T-cell infiltration in the CSF and in the brain during neurotoxicity resulting in pan-encephalitis, accompanied by increased levels of proinflammatory cytokines in the CSF. <i>Cancer Discov; 8(6); 750–63. ©2018 AACR.</i></p><p><i>This article is highlighted in the In This Issue feature, p. 663</i></p></div>

<div>Abstract<p>Chimeric antigen receptor (CAR) T-cell therapy is effective in the treatment of cancers of hematopoietic origin. In the immunosuppressive solid tumor environment, CAR T cells encounter obstacles that compromise their efficacy. We developed a strategy to address these barriers by having CAR T cells secrete single-domain antibody fragments [variable heavy domain of heavy chain antibodies (VHH) or nanobodies] that can modify the intratumoral immune landscape and thus support CAR T-cell function in immunocompetent animals. VHHs are small in size and able to avoid domain swapping when multiple nanobodies are expressed simultaneously—features that can endow CAR T cells with desirable properties. The secretion of an anti-CD47 VHH by CAR T cells improves engagement of the innate immune system, enables epitope spreading, and can enhance the antitumor response. CAR T cells that secrete anti–PD-L1 or anti–CTLA-4 nanobodies show improved persistence and demonstrate the versatility of this approach. Furthermore, local delivery of secreted anti-CD47 VHH-Fc fusions by CAR T cells at the tumor site limits their systemic toxicity. CAR T cells can be further engineered to simultaneously secrete multiple modalities, allowing for even greater tailoring of the antitumor immune response.</p></div>

Anti-CD19 CAR T Therapy Following Autologous HSCT May be Safe and Effective in Patients with Refractory Large B-Cell Lymphoma

Glioblastoma is a highly aggressive and difficult-to-treat brain cancer that resists conventional therapies. Recent advances in chimeric antigen receptor (CAR) T-cell therapy have shown promising potential for treating glioblastoma; however, achieving optimal efficacy remains challenging due to tumor antigen heterogeneity, the tumor microenvironment, and T-cell exhaustion. In this study, we developed a mathematical model of CAR T-cell therapy for glioblastoma to explore combinatorial antigen targeting with multiple CAR T-cell treatments that take into account the spatial heterogeneity of antigen expression. Our hybrid model, created using the multicellular modeling platform PhysiCell, couples partial differential equations that describe the tumor microenvironment with agent-based models for glioblastoma and CAR T-cells. The model captures cell-to-cell interactions between the glioblastoma cells and CAR T-cells throughout treatment, focusing on three target antigens–IL-13Rα2, HER2, and EGFR. We analyze tumor antigen expression heterogeneity informed by expression patterns identified from human tissues and investigate patient-specific combinatorial multiple CAR T-cell treatment strategies. Our model demonstrates that an early intervention is the most effective approach, especially in glioblastoma tumors characterized by mixed antigen expression. However, in tissues with clustered antigen patterns, we find that sequential administration with specific CAR T-cell types can achieve efficacy comparable to simultaneous administration. For instance, the percent tumor reduction is 7.1% for simultaneous administration versus 6.7% for sequential administration. In addition, spatially targeted delivery of CAR T-cells to specific tumor regions with matching antigen is an effective strategy as well, resulting in up to 19.6% greater tumor reduction with multi-location administration compared to baseline injection. Our model provides a valuable platform for developing patient-specific CAR T-cell treatment plans with the potential to optimize scheduling and locations of CAR T-cell injections based on individual antigen expression profiles.