CMG901, a Claudin18.2-specific antibody-drug conjugate, for the treatment of solid tumors

Abstract

Claudin18.2 has been recently recognized as a potential therapeutic target for gastric/gastroesophageal junction or pancreatic cancer. Here, we develop a Claudin18.2-directed antibody-drug conjugate (ADC), CMG901, with a potent microtubule-targeting agent MMAE (monomethyl auristatin E) and evaluate its preclinical profiles. In vitro studies show that CMG901 binds specifically to Claudin18.2 on the cell surface and kills tumor cells through direct cytotoxicity, antibody-dependent cellular cytotoxicity (ADCC), complement-dependent cytotoxicity (CDC), and bystander killing activity. In vivo pharmacological studies show significant antitumor activity in patient-derived xenograft (PDX) models. Toxicity studies show that the major adverse effects related to CMG901 are reversible hematopoietic changes attributed to MMAE. The highest non-severely toxic dose (HNSTD) is 6 mg/kg in cynomolgus monkeys and 10 mg/kg in rats once every 3 weeks. CMG901's favorable preclinical profile supports its entry into the human clinical study. CMG901 is currently under phase 3 investigation in patients with advanced gastric/gastroesophageal junction adenocarcinoma expressing Claudin18.2 (NCT06346392).

Keywords: ADC; CMG901; Claudin18.2; solid tumors.

Graphical abstract

Figure 1

Binding, internalization, and trafficking into lysosome of CMG901 (A and B) Binding of CMG901 (anti-CLDN18.2 ADC), CM311 (anti-CLDN18.2 mAb), anti-KLH hIgG1, and anti-KLH hIgG1 ADC on human Claudin18.2-expressing KATOIII (A) or HEK293 (B) cells. Data are represented as mean ± SD (n = 2). (C and D) Binding of CM311 and zolbetuximab on 3T3-hCLDN18.2^High cells with high Claudin18.2 expression (C) or 3T3-hCLDN18.2^Dim cells with low Claudin18.2 expression (n = 1). (E) Endocytosis rate of CMG901 or CM311 (n = 1). (F) Tracing of CMG901 or CM311 entering into the lysosome of KATOIII-hCLDN18.2 (n = 1). (G) Colocalization of CMG901 (red) and the lysosome marker LAMP-1 (green).

Figure 2

In vitro cytotoxicity of CMG901 (A and B) Cytotoxicity of CMG901, CM311, anti-KLH hIgG1, and anti-KLH hIgG1 ADC on KATOIII-hCLDN18.2 (A) and HEK293-hCLDN18.2 (B). Data are represented as mean ± SD (n = 3). (C and D) ADCC of CMG901, CM311, anti-KLH hIgG1, and anti-KLH hIgG1 ADC on KATOIII-hCLDN18.2 (C) and HEK293-hCLDN18.2 (D). Data are represented as mean ± SD (n = 2). (E and F) CDC of CMG901, CM311, anti-KLH hIgG1, and anti-KLH hIgG1 ADC on KATOIII-hCLDN18.2 (E) and HEK293-hCLDN18.2 (F). Data are represented as mean ± SD (n = 2). (G) Bystander killing effect of CMG901 on Claudin18.2-negative organoids. (H) Bystander killing effect of CMG901 on Claudin18.2-negative cell lines.

Figure 3

In vivo antitumor activity of CMG901 (A) Tumor volume of the PDX model STO#025. Data are represented as mean ± SEM (n = 10). (B) Tumor volume of the PDX model PAN#026. Data are represented as mean ± SEM (n = 10). (C) Tumor volume of the PDX model STO#580. Data are represented as mean ± SEM (n = 10). (D) Tumor volume of the PC-PDOX model. Data are represented as mean ± SEM (n = 6). (E) Efficacy study of the combination of CMG901 and anti-PD-1 on HSC-NPG humanized PDX model STO#025. Data are represented as mean ± SEM (n = 6). (F) Efficacy study of the combination of CMG901 and anti-PD-1 on MC38 syngeneic mouse model. MC38-hCLDN18.2 xenografts were grown subcutaneously in C57BL/6 mice and treated with different doses of CMG901 and anti-PD-1. Data are represented as mean ± SEM (n = 5). (G) CD8⁺T cell infiltration in tumors. Data are represented as mean ± SEM (n = 3–4). (H) NK cell infiltration in tumors. Data are represented as mean ± SEM (n = 3–5). ^∗indicates statistical significance compared to the vehicle group, ^#denotes significance compared to the CM311 group. ^∗p & ^#p < 0.05, ^∗∗p & ^##p < 0.01, ^∗∗∗p & ^###p < 0.001.

Figure 4

Pharmacokinetics study of CMG901 in cynomolgus monkeys and rats (A) Tissue cross-reactivity (TCR) study of CMG901 or CM311 in human, cynomolgus monkey, and rat. (B) Mean concentration-time curves of CMG901, total antibody (TAb), and MMAE in the CMG901 dose groups (1, 3, and 6 mg/kg) after the first dose by intravenous injection in cynomolgus monkeys for 10 weeks. Data are represented as mean ± SD (n = 5). (C) Mean concentration-time curves of CMG901, TAb, and MMAE in the CMG901 dose groups (2.5, 5, and 10 mg/kg) after the first dose by intravenous injection in rats for 10 weeks. Data are represented as mean ± SD (n = 5). (D) Precipitated radioactivity distributions in different tissues/body fluids after a single intravenous dose of ¹²⁵I-CMG901 in rats (n = 6). (E) Plasma stability of CMG901 in human, cynomolgus monkey, and rat plasma.