Innovent Biologics has reported a phase 3 victory for IBI343, boosting the prospects of an antibody-drug conjugate (ADC) that Takeda bet big on last year.
IBI343, also called arcotatug tavatecan and TAK-921, is designed to deliver a cytotoxic exatecan payload to cells that express CLDN18.2. Astellas won FDA approval for an anti-CLDN18.2 antibody in 2024. But rival drug developers have identified chances to hit the target, a transmembrane protein also known as Claudin-18.2, with novel modalities to improve outcomes.
The phase 3 win cements Innovent’s place at the front of the race to launch next-generation CLDN18.2 drugs. Innovent delivered the victory in a phase 3 clinical trial that enrolled 464 people in China and Japan with locally advanced unresectable or metastatic CLDN18.2-positive gastric or gastroesophageal junction adenocarcinoma. Patients had received at least two prior systemic therapies.
At the first interim analysis, progression-free survival (PFS) was significantly longer on IBI343 than on investigator-selected control therapies, which included chemotherapy drugs. PFS was one of the study’s primary endpoints.
Innovent’s statement lacks the numbers behind the PFS victory or adverse event data. Physicians quoted in the press release called the efficacy “excellent” and safety and tolerability “good,” with a low rate of gastrointestinal-related toxicity. Innovent is keeping the data back for academic conferences or journals. The biotech has yet to comment on the other primary endpoint, overall survival.
China’s National Medical Products Administration has accepted IBI343 for priority review. The filing is the first time a CLDN18.2-directed ADC has begun regulatory review, Innovent said. Innovent retained rights to the drug candidate in Greater China when it partnered the program with Takeda last year.
Takeda paid $1.2 billion for ex-China rights to IBI343 and a bispecific candidate, IBI363, which Takeda execs discussed with Fierce at ASCO last week. Studies of IBI343 in first-line gastric and pancreatic cancer are underway.
Multiple companies are pursuing the same opportunities. AstraZeneca licensed a CLDN18.2 bispecific in 2022 and struck a deal for an ADC the next year. Astellas picked up an ADC last year as rivals circled its nascent CLDN18.2 franchise. Moderna entered the field in 2023. Merck & Co. had a CLDN18.2 candidate from its Kelun-Biotech collaboration but returned the ADC in 2024.