Keymed Biosciences Inc. announced that the latest data from a Phase I clinical study of CMG901 (also known as AZD0901), a Claudin 18.2-targeted antibody-drug conjugate, in the treatment of advanced gastric/gastroesophageal junction (G/GEJ) cancer has been presented by way of oral presentation at the American Society of Clinical Oncology (ASCO) Annual Meeting 2024. This presentation represents an update of previously presented data at November 2023 session of the ASCO Plenary Series, with a median follow-up of 10.1 months. The KYM901 trial (NCT04805307) was designed to evaluate the safety and tolerability, pharmacokinetics, immunogenicity, and preliminary efficacy of CMG901 in patients with advanced solid tumors.

As of February 24, 2024, a total of 113 patients with G/GEJ cancer received CMG901 at doses of 2.2 mg/kg, 2.6 mg/kg and 3.0 mg/kg (n=44, 50, and 19, respectively). The median lines of prior therapy of the patients was two. 74% of patients previously received anti- PD-1/PD-L1 therapy.

Among 89 evaluable patients with Claudin 18.2-high (defined as 2+ membrane staining intensity in 20% tumor cells) G/GEJ cancer in the 2.2-3.0 mg/kg cohorts, the confirmed objective response rate (ORR) and confirmed disease control rate (DCR) were 35% and 70%, respectively. A confirmed ORR of 48% was observed in the 2.2 mg/kg cohort. For all 93 patients with Claudin 18.

2-high G/GEJ cancer, the median progression-free survival (mPFS) and the median overall survival (mOS) were 4.8 months and 11.8 months, respectively. In terms of safety, among the 113 patients with G/GE J cancer in the 2.2 to 3 treatment-emergent adverse events (TEAEs) occurred in 55% of patients, and drug-related serious AEs were reported in 32% of patients. 8% of patients discontinued CMG901 treatment due to drug-related AEs.

Overall, CMG901 had a manageable safety and tolerability profile, and most adverse events were well-managed through prophylactic medications or standard treatment management while continuing CMG901 treatment. CMG901 demonstrated promising efficacy in patients with advanced Claudin 18.2- high G/GEJ cancer.