Immutep (IMMP) said early Wednesday that the United States Food and Drug Administration has granted orphan drug designation to eftilagimod alfa for the treatment of soft tissue sarcoma, a rare cancer.

Shares of the company surged more than 58% in recent premarket activity.

The move follows clinical data from a phase 2 trial that evaluated efti in combination with radiotherapy and Keytruda (pembrolizumab). In 38 patients, the study met its primary endpoint, demonstrating a median tumor hyalinization/fibrosis of almost 52%, exceeding the pre-specified target of 35% and historical benchmarks of about 15% with radiotherapy alone. Tumor hyalinization/fibrosis refers to healing.

The company said the results were observed across multiple sarcoma subtypes and showed immune activation consistent with efti, with a favourable safety profile and no delays to planned surgery.

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