A Novel GUCY2C-CD3 T-Cell Engaging Bispecific Construct (PF-07062119) for the Treatment of Gastrointestinal Cancers

Abstract

Purpose: Gastrointestinal cancers remain areas of high unmet need despite advances in targeted and immunotherapies. Here, we demonstrate potent, tumor-selective efficacy with PF-07062119, a T-cell engaging CD3 bispecific targeting tumors expressing Guanylyl Cyclase C (GUCY2C), which is expressed widely across colorectal cancer and other gastrointestinal malignancies. In addition, to address immune evasion mechanisms, we explore combinations with immune checkpoint blockade agents and with antiangiogenesis therapy. Experimental Design: PF-07062119 activity was evaluated in vitro in multiple tumor cell lines, and in vivo in established subcutaneous and orthotopic human colorectal cancer xenograft tumors with adoptive transfer of human T cells. Efficacy was also evaluated in mouse syngeneic tumors using human CD3e transgenic mice. IHC and mass cytometry were performed to demonstrate drug biodistribution, recruitment of activated T cells, and to identify markers of immune evasion. Combination studies were performed with anti-PD-1/PD-L1 and anti-VEGF antibodies. Toxicity and pharmacokinetic studies were done in cynomolgus macaque. Results: We demonstrate that GUCY2C-positive tumors can be targeted with an anti-GUCY2C/anti-CD3e bispecific, with selective drug biodistribution to tumors. PF-07062119 showed potent T-cell-mediated in vitro activity and in vivo efficacy in multiple colorectal cancer human xenograft tumor models, including KRASand BRAF-mutant tumors, as well as in the immunocompetent mouse syngeneic tumor model. PF-07062119 activity was further enhanced when combined with anti-PD-1/ PD-L1 treatment or in combination with antiangiogenic therapy. Toxicity studies in cynomolgus indicated a monitorable and manageable toxicity profile. Conclusions: These data highlight the potential for PF-07062119 to demonstrate efficacy and improve patient outcomes in colorectal cancer and other gastrointestinal malignancies.

Combination of T-Cell Bispecific Antibodies With PD-L1 Checkpoint Inhibition Elicits Superior Anti-Tumor Activity

“…TCB-induced T-cell activation is has been shown to upregulate PD-1 expression on T-cells and induce PD-L1 expression on tumor cells (IFNg driven) (8,9,(25)(26)(27)(28)(29). This may lead to adaptive immune resistance mechanisms related to the TCB mode of action, similar to what has been described for checkpoint inhibition (30,31).…”

“…A clear upregulation of both PD-1 (on CD4 and CD8 T-cells) as well as PD-L1 (on tumor cells and CD4 and CD8 T-cells) was detected in response to CEA-TCB treatment, indicative of the PD-1/PD-L1 axis being one of the adaptive resistance mechanisms related to TCB activity (8,9,(25)(26)(27)(28)(29). Combination of TCBs with anti-PD-L1 blocking antibody (in different tumor and mouse models and using different TCBs targeting both CEA (solid tumors) and CD20 (hematological malignancies) consistently translated into superior anti-tumor efficacy and stronger tumor growth inhibition when compared to either agent given as monotherapy.…”

A Bispecific DLL3/CD3 IgG-Like T-Cell Engaging Antibody Induces Antitumor Responses in Small Cell Lung Cancer

“…After formation of the cytolytic synapse, the T-cells produce perforin and granzyme B, leading to apoptosis of the tumor cells. Activation of T-cells leads to transient release of cytokines, which engages other immune cells and broadens the immune response against the tumor tissue leading to conversion of a noninflamed (cold) to an inflamed (hot) tumor environment, infiltration and proliferation of T-cells, and serial killing of tumor cells (10)(11)(12)(13). After recent clinical successes of bispecific T-cell engagers with a short half-life (BiTE) for the treatment of hematologic malignancies (14,15), the next generation of T-cell engagers incorporating half-life extension for increased dosing convenience for patients for the treatment of solid tumors is emerging (13,(16)(17)(18).…”

Discovery and optimization of a novel anti-GUCY2c x CD3 bispecific antibody for the treatment of solid tumors

“…[16][17][18] Expression of GUCY2C is confined to the luminal surfaces of healthy intestinal epithelium, and because tumors have disrupted tight junction architecture, GUCY2C may offer a promising target antigen for tumor-specific activation of systemically administered T cell redirection therapies. [19][20][21] GUCY2C cell-surface expression is reported to be higher on moderately to well-differentiated tumors compared to more poorly differentiated tumors. 21 We therefore sought to develop an anti-GUCY2C/anti-CD3ε T-BsAb that demonstrated potent in vitro cytotoxicity (EC 50 below 1 nM) and in vivo single-agent efficacy below 1 mg/kg in preclinical models, good tolerability in cynomolgus monkeys at the predicted human efficacious dose, a pharmacokinetic (PK) profile compatible with dosing every three weeks, and developability characteristics supporting clinical development.…”

“…[19][20][21] GUCY2C cell-surface expression is reported to be higher on moderately to well-differentiated tumors compared to more poorly differentiated tumors. 21 We therefore sought to develop an anti-GUCY2C/anti-CD3ε T-BsAb that demonstrated potent in vitro cytotoxicity (EC 50 below 1 nM) and in vivo single-agent efficacy below 1 mg/kg in preclinical models, good tolerability in cynomolgus monkeys at the predicted human efficacious dose, a pharmacokinetic (PK) profile compatible with dosing every three weeks, and developability characteristics supporting clinical development.…”