Antitumor activity of AZD0754, a dnTGFβRII-armored, STEAP2-targeted CAR-T cell therapy, in prostate cancer
Peter Zanvit, … , Gordon Moody, Emily E. Bosco
Peter Zanvit, … , Gordon Moody, Emily E. Bosco
Published November 15, 2023
Citation Information: J Clin Invest. 2023;133(22):e169655. https://doi.org/10.1172/JCI169655.
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Research Article Oncology

Antitumor activity of AZD0754, a dnTGFβRII-armored, STEAP2-targeted CAR-T cell therapy, in prostate cancer

Abstract

Prostate cancer is generally considered an immunologically “cold” tumor type that is insensitive to immunotherapy. Targeting surface antigens on tumors through cellular therapy can induce a potent antitumor immune response to “heat up” the tumor microenvironment. However, many antigens expressed on prostate tumor cells are also found on normal tissues, potentially causing on-target, off-tumor toxicities and a suboptimal therapeutic index. Our studies revealed that six-transmembrane epithelial antigen of prostate-2 (STEAP2) was a prevalent prostate cancer antigen that displayed high, homogeneous cell surface expression across all stages of disease with limited distal normal tissue expression, making it ideal for therapeutic targeting. A multifaceted lead generation approach enabled development of an armored STEAP2 chimeric antigen receptor T cell (CAR-T) therapeutic candidate, AZD0754. This CAR-T product was armored with a dominant-negative TGF-β type II receptor, bolstering its activity in the TGF-β–rich immunosuppressive environment of prostate cancer. AZD0754 demonstrated potent and specific cytotoxicity against antigen-expressing cells in vitro despite TGF-β–rich conditions. Further, AZD0754 enforced robust, dose-dependent in vivo efficacy in STEAP2-expressing cancer cell line–derived and patient-derived xenograft mouse models, and exhibited encouraging preclinical safety. Together, these data underscore the therapeutic tractability of STEAP2 in prostate cancer as well as build confidence in the specificity, potency, and tolerability of this potentially first-in-class CAR-T therapy.

Authors

Peter Zanvit, Dewald van Dyk, Christine Fazenbaker, Kelly McGlinchey, Weichuan Luo, Jessica M. Pezold, John Meekin, Chien-ying Chang, Rosa A. Carrasco, Shannon Breen, Crystal Sao-Fong Cheung, Ariel Endlich-Frazier, Benjamin Clark, Nina J. Chu, Alessio Vantellini, Philip L. Martin, Clare E. Hoover, Kenesha Riley, Steve M. Sweet, David Chain, Yeoun Jin Kim, Eric Tu, Nathalie Harder, Sandrina Phipps, Melissa Damschroder, Ryan N. Gilbreth, Mark Cobbold, Gordon Moody, Emily E. Bosco

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Figure 5

dnTGFβRII CAR-T armoring enhances activity and persistence in vitro and in vivo.

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dnTGFβRII CAR-T armoring enhances activity and persistence in vitro and ...
(A) Serial killing was measured following coculture of LNCaP and CART-T cells at an E/T ratio of 0.3:1, as indicated by arrowheads. (B) Cytokines were profiled 24 hours after each coculture in A. (C) The 40A3Bz and 40A3Bz CAR-Ts were dosed at 3 concentrations (0.5 × 106, 2.5 × 106, and 5 × 106 CAR-positive cells) by tail vein injection in NSG mice implanted with C4-2 cells overexpressing TGF-β (n = 10). Tumor volumes and body weights were measured. (D) For C, a cohort of animals from each group were sacrificed to examine CAR-T pharmacodynamics and phenotype in dissociated tumors by FACS (n = 4). Representative plots revealed the percentage of tumor-infiltrated human CD45+ (hCD45+) cells in mice dosed with 5 × 106 cells at day 14. Bottom bar graph shows CAR-positive, tumor-infiltrated 40A3Bz cells (paratope+ TGFβRII– hCD45+) and 40A3Bz dnTGFβRII CAR-Ts (paratope+ TGFβRII+ hCD45+). (E) Paratope-positive cells from D were analyzed for the percentage of IFN-γ+, TNF+, and IL-2+ cells in mice at day 14. (F) As in E, cells were analyzed for expression of Tim3+, Lag3+, and PD-1+ cells. UMAP plots in E and F show populations identified by a FlowSOM algorithm and further defined by heatmap. (G) Similarly to C, mice bearing 22RV1 cells overexpressing TGF-β, and 40A3Bz dnTGFβRII CAR-Ts were dosed at 3 concentrations (3 × 106, 7 × 106, and 12 × 106 CAR-positive cells) (n = 10). (H) C4-2 luciferase-expressing cells were implanted in the intratibial space of NSG mice, and luciferase signal was monitored. Randomization occurred when the tumor flux reached 4.04 × 108 photons/second (p/s), and CAR-Ts from C were dosed at 3 concentrations (0.1 × 106, 0.5 × 106, and 1 × 106 CAR-positive cells). (n = 5). Data shown in A–C and G are representative of 3 independent experiments using CAR-Ts from 2 donors. H and D–F were performed twice with material from 2 donors. All error bars represent mean ± SEM. Statistical significance was determined using 1-sided growth rate comparison nonparametric test in C and H and unpaired 2-tailed Student’s t test in E and F (*P < 0.05, **P < 0.01, ***P < 0.001).