Celltrion announced on the 6th through a regulatory filing that it has applied to the U.S. Food and Drug Administration (FDA) for an amendment to the protocol of its global Phase 3 clinical trial in the U.S. for 'CT-P51,' a biosimilar candidate to the anticancer drug 'Keytruda' (ingredient name: pembrolizumab).

According to the filing, the amendment application was submitted to the FDA on July 6, 2026, local time, with the date of occurrence being the same day.

■ Clinical Trial Overview

CT-P51 is a global Phase 3 clinical trial that compares the efficacy and safety of the candidate with those of the original drug, Keytruda, in patients with previously untreated metastatic non-squamous non-small cell lung cancer (NSCLC). The trial will be conducted as a double-blind, randomized, active-controlled study involving a total of 220 patients over a treatment period of two years.

Celltrion plans to continue the development of the biosimilar by comparing the efficacy and safety of CT-P51 and Keytruda through this trial.

■ Investment Cautions

The company also disclosed investment precautions in the filing. It explained that the statistical probability of an investigational drug receiving final approval as a medicinal product is known to be around 10%, and that the clinical trial and product approval processes may yield results that fall short of expectations.

Accordingly, the company added that there is a possibility of altering or abandoning its commercialization plans, and therefore, investors should carefully consider the investment risks disclosed in real-time filings and business reports before making investment decisions.

Meanwhile, Celltrion stated that the content of this filing will be utilized for future press releases and IR materials. CT-P51's U.S. Phase 3 clinical trial plan was initially submitted in June 2024, and the trial protocol was approved in August of the same year.