Immutep Wins FDA Orphan Drug Status for Eftilagimod Alfa in Soft Tissue Sarcoma

FDA Orphan Drug Status Highlights Eftilagimod Alfa's Promise in Rare Cancer

Immutep Limited (ASX:IMM, NASDAQ: IMMP) has secured a significant regulatory nod with the FDA granting Orphan Drug Designation (ODD) for its lead immunotherapy, eftilagimod alfa (efti), targeting soft tissue sarcoma (STS). This rare and challenging cancer affects fewer than 200,000 people in the US, positioning efti for potential seven years of market exclusivity and other regulatory incentives if approved.

The designation reflects the FDA's recognition of efti's potential based on encouraging clinical data from the Phase II EFTISARC-NEO trial. This investigator-led study combined efti with radiotherapy and Merck’s KEYTRUDA® (pembrolizumab) in a neoadjuvant setting for patients with resectable STS. Among 38 evaluable patients, the trial surpassed its primary endpoint with a median tumour hyalinization/fibrosis of 51.5%, well beyond the 35% target and historical 15% benchmark seen with radiotherapy alone.

Clinical Data Supports Immune Activation and Safety

The positive tumour response was consistent across multiple sarcoma subtypes and accompanied by translational evidence of immune activation aligned with efti’s mechanism of action. Importantly, the combination therapy maintained a favourable safety profile without causing delays to planned surgeries, a crucial consideration for neoadjuvant treatments.

CEO Marc Voigt highlighted the FDA’s recognition as a meaningful endorsement of efti’s potential in a rare disease with high unmet need. However, he also noted that Immutep is conducting a comprehensive review following the discontinuation of its Phase III TACTI-004 trial in non-small cell lung cancer (NSCLC). This reassessment will shape future clinical trial decisions for efti, with the current designation offering a promising direct route into late-stage trials in STS.

This regulatory milestone arrives shortly after Immutep’s strategic pivot following the halted TACTI-004 trial, which had cast uncertainty over efti’s development trajectory. The company’s recent Phase III trial update and the earlier decision to halt the pivotal NSCLC study underscore the importance of this orphan drug pathway as a potential catalyst for renewed clinical focus.

Immutep’s Position in Immuno-Oncology and Future Prospects

Immutep continues to leverage its expertise in LAG-3 biology, aiming to harness immune modulation for cancer and autoimmune diseases. While the setback in NSCLC has tempered near-term expectations, the orphan drug designation for STS represents a strategic inflection point. It opens the door to regulatory benefits such as tax credits and fee waivers, which could ease development costs and timelines.

Investors will be watching how Immutep’s management balances the opportunity in soft tissue sarcoma against the broader challenges of late-stage clinical development. The company’s next moves on trial design and capital allocation will be critical to unlocking value from efti’s promising Phase II results and navigating the competitive oncology landscape.