Celltrion (KRX:068270) voluntarily terminated and withdrew its European Phase 3 clinical trial application for CT-P51, its biosimilar to cancer drug Keytruda, from the European Medicines Agency, according to a regulatory filing on Tuesday.

The South Korean biopharmaceutical company said the withdrawal follows changes in the global regulatory environment for biosimilar clinical trials.

The company has updated its clinical and regulatory strategy for Phase 3 trials in previously untreated metastatic non-squamous non-small cell lung cancer, reducing the number of patients recruited for the trial.

The company will continue the Phase 3 study in participating countries outside the European Union, comparing the efficacy and safety of CT-P51 against the reference drug Keytruda.