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

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-ß type II receptor, bolstering its activity in the TGF-ß-rich immunosuppressive environment of prostate cancer. AZD0754 demonstrated potent and specific cytotoxicity against antigen-expressing cells in vitro despite TGF-ß-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.

Cartilage-Targeted IGF-1 Treatment to Promote Longitudinal Bone Growth.

Recombinant human growth hormone (GH) is commonly used to treat short stature in children. However, GH treatment has limited efficacy, particularly in severe, non-GH-deficient conditions such as chondrodysplasias, and potential off-target effects. Because short stature results from decreased growth plate chondrogenesis, we developed a cartilage-targeting single-chain human antibody fragment (CaAb) aiming to deliver therapeutic molecules to the growth plate, thereby increasing treatment efficacy while minimizing adverse effects on other tissues. To this end, we created fusion proteins of these CaAbs conjugated with insulin-like growth factor 1 (IGF-1), an endocrine and/or paracrine factor that positively regulates chondrogenesis. These CaAb-IGF-1 fusion proteins retained both cartilage binding and IGF-1 biological activity, and they were able to stimulate bone growth in an organ culture system. Using a GH-deficient (lit) mouse model, we found that subcutaneous injections of these CaAb-IGF-1 fusion proteins increased overall growth plate height without increasing proliferation in kidney cortical cells, suggesting on-target efficacy at the growth plate and less off-target effect on the kidney than IGF-1 alone. Alternate-day injections of these fusion proteins, unlike IGF-1 alone, were sufficient to produce a therapeutic effect. Our findings provide proof of principle that targeting therapeutics to growth plate cartilage can potentially improve treatment for childhood growth disorders.

An RNA-directed nucleoside anti-metabolite, 1-(3-C-ethynyl-beta-d-ribo-pentofuranosyl)cytosine (ECyd), elicits antitumor effect via TP53-induced Glycolysis and Apoptosis Regulator (TIGAR) downregulation.

1-(3-C-ethynyl-beta-d-ribo-pentofuranosyl)cytosine (ECyd) is a ribose-modified nucleoside analog of cytidine with potent anticancer activity in several cancers. The main antitumor mechanism of this promising RNA-directed nucleoside anti-metabolite is efficient blockade of RNA synthesis in cancer cells. Here, we examined the therapeutic potential of this RNA-directed anti-metabolite in in vitro models of nasopharyngeal cancer (NPC). In a panel of 6 NPC cell lines, ECyd effectively inhibited cellular proliferation at nM concentrations (IC(50): approximately 13-44nM). Moreover, cisplatin-resistant NPC cells were highly sensitive to ECyd (at nM concentration). The ECyd-mediated growth inhibition was associated with G(2)/M cell cycle arrest, PARP cleavage (a hallmark of apoptosis) and Bcl-2 downregulation, indicating induction of apoptosis by ECyd in NPC cells. Unexpectedly, ECyd-induced significant downregulation of TIGAR, a newly described dual regulator of apoptosis and glycolysis. More importantly, this novel action of ECyd on TIGAR was accompanied by marked depletion of NADPH, the major reducing power critically required for cell proliferation and survival. We hypothesized that ECyd-induced TIGAR downregulation was crucially involved in the antitumor activity of ECyd. Indeed, overexpression of TIGAR was able to rescue NPC cells from ECyd-induced growth inhibition, demonstrating a novel mechanistic action of ECyd on TIGAR. We demonstrated for the first time that an RNA-directed nucleoside analog, ECyd, exerts its antitumor activity via downregulation of a novel regulator of apoptosis, TIGAR. Moreover, ECyd may represent a novel therapy for NPC.

Leachianone A as a potential anti-cancer drug by induction of apoptosis in human hepatoma HepG2 cells.

The Chinese herbal medicine Radix Sophorae is widely applied as an anti-carcinogenic/ anti-metastatic agent against liver cancer. In this study, Leachianone A, isolated from Radix Sophorae, possessed a profound cytotoxic activity against human hepatoma cell line HepG2 in vitro, with an IC(50) value of 3.4microg/ml post-48-h treatment. Its action mechanism via induction of apoptosis involved both extrinsic and intrinsic pathways. Its anti-tumor effect was further demonstrated in vivo by 17-54% reduction of tumor size in HepG2-bearing nude mice, in which no toxicity to the heart and liver tissues was observed. In conclusion, this is the first report describing the isolation of Leachianone A from Radix Sophorae and the molecular mechanism of its anti-proliferative effect on HepG2 cells.

Proteomic characterization of Sophoraflavone J-induced apoptosis in HepG2 cells.

Chinese herb Radix sophorae is widely applied as an anticarcinogenic/antimetastatic agent against liver cancers. In the current study, Sophoraflavone J, a flavonoid constituent enriched in the root of Radix sophorae, induced apoptosis in human hepatoma HepG2 cells via the intrinsic mitochondrial death pathway. The molecular mechanism of the cytotoxic effect was further investigated by a comparative proteomic approach. Differentially expressed proteins identified included membrane proteins/antigens, structural proteins, transcriptional factors, glycolytic enzymes, heat-shock chaperon proteins, ROS-related proteins and proteosomes, etc. These findings were further validated by Western blot analysis and real-time PCR. Preliminary experiments to characterize the roles of these proteins were conducted. Our data suggested that Sophoraflavone J treatment triggered nutrient depletion and generation of ROS in cells, which subsequently led to mitochondrial dysfunction and apoptosis.