Immutep Secures FDA Orphan Status for Efti in Sarcoma

Sydney, Australia | April 15, 2026

Immutep Limited has achieved a significant regulatory milestone with the U.S. Food and Drug Administration (FDA) granting Orphan Drug Designation (ODD) to eftilagimod alfa (efti) for the treatment of soft tissue sarcoma (STS), a rare and difficult-to-treat cancer. This designation highlights the growing importance of innovative immunotherapies in oncology and reinforces Immutep’s position as a leader in LAG-3-based immune modulation therapies. The FDA’s decision reflects both the unmet medical need in STS and the promising clinical data supporting efti’s mechanism of action and therapeutic potential.

FDA Orphan Drug Designation Strengthens Regulatory Pathway

The Orphan Drug Designation program is designed to accelerate the development of treatments for rare diseases affecting fewer than 200,000 patients in the United States. With this designation, efti becomes eligible for several regulatory incentives, including tax credits, fee waivers, regulatory assistance, and up to seven years of market exclusivity upon approval. These benefits significantly enhance the commercial and developmental viability of the therapy, allowing Immutep to advance its clinical strategy more efficiently. Importantly, the designation also signals regulatory confidence in the clinical potential of efti, positioning it as a strong candidate for late-stage development in soft tissue sarcoma.

Phase II Clinical Data Demonstrates Strong Efficacy Signal

The FDA’s decision is supported by encouraging results from the Phase II EFTISARC-NEO trial, which evaluated efti in combination with radiotherapy and pembrolizumab in patients with resectable STS. The study met its primary endpoint, demonstrating a median tumour hyalinization/fibrosis rate of 51.5%, significantly exceeding the predefined target of 35% and outperforming historical benchmarks of approximately 15% with radiotherapy alone.

These results were consistent across multiple sarcoma subtypes and were further supported by translational data showing immune activation aligned with efti’s mechanism of action. Additionally, the therapy exhibited a favourable safety profile, with no delays to planned surgical interventions, underscoring its clinical feasibility in neoadjuvant settings.

Advancing Immunotherapy Innovation in Rare Oncology

Eftilagimod alfa is part of Immutep’s broader portfolio of LAG-3-based immunotherapies, which are designed to modulate immune responses and enhance anti-tumor activity. By targeting the Lymphocyte Activation Gene-3 (LAG-3) pathway, efti aims to activate antigen-presenting cells and boost T-cell responses, offering a novel approach to cancer treatment. The ODD recognition not only validates this mechanism but also provides a potential pathway for accelerated clinical development and future regulatory approvals. The company is currently evaluating its next steps following recent strategic reviews, with the possibility of advancing directly into late-stage clinical trials in the neoadjuvant setting.

Strategic Impact on Oncology Drug Development

The FDA’s designation represents a critical step forward in addressing the high unmet need in soft tissue sarcoma, where treatment options remain limited and outcomes are often poor. By advancing a first-in-class immunotherapy approach, Immutep is contributing to the evolution of precision oncology and next-generation cancer therapies. The development of efti also aligns with broader industry trends toward combination therapies and immune system modulation, which are increasingly shaping modern cancer treatment paradigms.

As regulatory agencies continue to prioritize therapies for rare diseases, innovations like efti are expected to play a key role in expanding treatment options and improving patient outcomes. The combination of strong clinical data, regulatory incentives, and scientific innovation positions Immutep to make a meaningful impact in the oncology landscape.

The FDA Orphan Drug Designation for eftilagimod alfa marks a pivotal milestone for Immutep and underscores the growing importance of immunotherapy in rare cancers. With promising Phase II results and a clear regulatory pathway, efti has the potential to advance into late-stage clinical development and redefine treatment strategies for soft tissue sarcoma. As the company continues to progress its pipeline, this development highlights the critical role of regulatory support and clinical innovation in accelerating next-generation cancer therapies, ultimately offering new hope to patients facing limited treatment options.

Source: Immutep press release