Immutep Receives FDA Orphan Drug Designation for Eftilagimod Alfa in Soft Tissue Sarcoma

Immutep (NASDAQ: IMMP) announced the FDA has granted Orphan Drug Designation for eftilagimod alfa (efti) to treat soft tissue sarcoma (STS) on April 15, 2026.

Rhea-AI Summary

Immutep (NASDAQ: IMMP) announced the FDA has granted Orphan Drug Designation for eftilagimod alfa (efti) to treat soft tissue sarcoma (STS) on April 15, 2026. The designation may provide regulatory support, tax credits, fee waivers and seven years of market exclusivity if approved.

Immutep cited investigator‑initiated Phase II EFTISARC‑NEO data in 38 evaluable patients showing median tumour hyalinization/fibrosis of 51.5%, above the pre‑specified 35% target and historical ~15% with radiotherapy alone; the study reported immune activation signals and a favourable safety profile without surgery delays.

Positive

• FDA granted Orphan Drug Designation for efti in STS
• Phase II EFTISARC‑NEO: median tumour hyalinization 51.5%
• Favourable safety profile with no delays to planned surgery
• ODD may provide seven years of market exclusivity upon approval

Negative

• Company discontinued the Phase III TACTI‑004 trial
• ODD is not an approval and does not guarantee regulatory success
• EFTISARC‑NEO data derived from 38 evaluable patients (investigator‑initiated)

Argus Apr 15 session

+72.81% close to close Open Argus

Details

News Market Reaction – IMMP

On Apr 15, the day this news came out, IMMP closed 72.81% above the previous close.

Data tracked by StockTitan Argus for the Apr 15 session.

Key Figures

Evaluable patients: 38 patients Median tumour hyalinization/fibrosis: 51.5% Pre-specified target: 35% +5 more

Evaluable patients

38 patients

EFTISARC-NEO Phase II trial in resectable soft tissue sarcoma

Median tumour hyalinization/fibrosis

51.5%

Primary endpoint in EFTISARC-NEO Phase II trial

Pre-specified target

35%

Primary endpoint benchmark for EFTISARC-NEO trial

Historical benchmark (radiotherapy alone)

15%

Historical tumour hyalinization/fibrosis with radiotherapy monotherapy

US prevalence threshold

200,000 people

ODD applies to diseases affecting fewer than this number in US

Market exclusivity period

7 years

US ODD market exclusivity upon approval

Current share price

$0.3148

Pre-news price context vs 52-week range

52-week performance vs high

-91.08%

Distance from 52-week high of $3.5299 before ODD news

Previous Clinical trial Reports

5 past events · Latest: Mar 19

Same Type 5 events

1. Mar 19

   Phase I progress

   24h Move

   -0.7%

   IMP761 Phase I SAD completed up to 14 mg/kg with no dose-limiting toxicities.

2. Mar 13

   Phase III futility stop

   24h Move

   -82.4%

   TACTI-004 Phase III in 1L NSCLC discontinued after interim futility analysis.

3. Feb 06

   Trial enrolment update

   24h Move

   +0.0%

   TACTI-004 reached 50% enrolment with 378 patients across 27 countries.

4. Dec 22

   Positive Phase I update

   24h Move

   +4.9%

   IMP761 Phase I showed favourable safety and durable immunosuppression signals.

5. Dec 16

   Phase III operational update

   24h Move

   +2.0%

   TACTI-004 Phase III for efti reported strong operational progress and enrolment.

24h Move is the share-price change in the day after each event; other market factors may also have contributed.

Key Terms

orphan drug designation, soft tissue sarcoma, neoadjuvant, phase ii, +2 more

6 terms

orphan drug designation regulatory

"the FDA has granted Orphan Drug Designation (ODD) for eftilagimod alfa"

Orphan drug designation is a special status given to medicines developed to treat rare diseases affecting only a small number of people. This status often provides benefits like faster approval processes and financial incentives, making it more attractive for companies to develop these drugs. For investors, it signals potential for exclusive market rights and reduced competition, which can impact the drug’s profitability.

soft tissue sarcoma medical

"for the treatment of Soft Tissue Sarcoma (STS), a rare cancer"

A soft tissue sarcoma is a type of cancer that starts in the body’s soft tissues — such as muscles, fat, nerves, blood vessels or connective tissue — rather than in organs or bones. For investors, it matters because treatments for these cancers drive drug development, clinical trial results and regulatory decisions; a successful therapy can create a meaningful commercial market while trial failures or safety issues can affect a company’s valuation and prospects.

neoadjuvant medical

"in the neoadjuvant setting in patients with resectable soft tissue sarcoma"

"Neoadjuvant" describes treatments or interventions that are given before the main or primary procedure, such as surgery or a major decision. It’s like preparing the ground before planting seeds, aiming to improve the final outcome. For investors, understanding neoadjuvant approaches can provide insight into how companies enhance results or effectiveness in their processes or products.

phase ii medical

"Phase II EFTISARC-NEO trial which has been evaluating efti"

Phase II is the mid-stage clinical trial where a potential drug or medical treatment is tested in a larger group of patients to see if it works and to help determine the best dose and common side effects. For investors, Phase II results matter because they give the first meaningful evidence about effectiveness and safety—like a road test that shows whether a product has real promise before a much bigger, costly final trial and potential regulatory approval.

pembrolizumab medical

"in combination with radiotherapy and KEYTRUDA® (pembrolizumab) in the neoadjuvant"

A cancer immunotherapy drug that helps the body’s immune system recognize and attack tumor cells by blocking a molecular “brake” that tumors use to hide. Investors watch it because regulatory approvals, clinical trial results, dosing rules, and competition directly affect potential sales, profit forecasts, and the valuation of companies that sell or license the drug—think of trial outcomes as checkpoint signs that can open or close a revenue road.

mechanism of action medical

"immune activation consistent with efti’s mechanism of action, with a favourable"

Mechanism of action describes how a drug, therapy, or medical product produces its effect in the body—the specific steps, targets, and biological processes it engages, like a key fitting into a lock to open a door. Investors care because a clear, well-understood mechanism reduces scientific uncertainty, supports regulatory approval and market confidence, and helps predict safety, effectiveness and additional uses, all of which influence a product’s commercial potential and a company’s valuation.

AI-generated analysis. How Rhea-AI works. Not financial advice.

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SYDNEY, AUSTRALIA, April 15, 2026 (GLOBE NEWSWIRE) -- Immutep Limited (ASX: IMM; NASDAQ: IMMP) (“Immutep” or “the Company”), a clinical-stage biotechnology company targeting cancer and autoimmune diseases, today announces that the United States Food and Drug Administration (FDA) has granted Orphan Drug Designation (ODD) for eftilagimod alfa (“efti”) for the treatment of Soft Tissue Sarcoma (STS), a rare cancer with significant unmet medical need.

The FDA’s Orphan Drug Designation program is designed to encourage development of therapies for rare diseases affecting fewer than 200,000 people in the United States. Benefits of ODD may include regulatory support, potential tax credits, fee exemptions, and seven years of market exclusivity upon approval.

This designation recognises the potential therapeutic relevance of efti in STS, supported by encouraging clinical data from the investigator-initiated Phase II EFTISARC-NEO trial which has been evaluating efti in combination with radiotherapy and KEYTRUDA^® (pembrolizumab) in the neoadjuvant setting in patients with resectable soft tissue sarcoma. In 38 evaluable patients, the study met its primary endpoint, demonstrating a median tumour hyalinization/fibrosis of 51.5%, significantly exceeding the pre-specified target of 35% and historical benchmarks of ~15% with radiotherapy alone.¹

These results were observed across multiple sarcoma subtypes and were supported by translational data showing immune activation consistent with efti’s mechanism of action, with a favourable safety profile and no delays to planned surgery.²

CEO of Immutep, Marc Voigt said: “We are pleased that the FDA has recognised the potential of efti for patients with soft tissue sarcoma, a rare and difficult to treat cancer. As previously communicated, the Company is currently undertaking a comprehensive review and analysis following the discontinuation of its Phase III TACTI-004 trial and the outcome will influence the decision regarding any potential future clinical trial with efti. The FDA’s designation, based on very encouraging data from the EFTISARC-NEO trial, provides us with a potential direct step forward into a late-stage study in the neoadjuvant setting for STS.”

About Immutep
Immutep is a clinical-stage biotechnology company developing novel immunotherapies for cancer and autoimmune diseases. The Company is a pioneer in the understanding and advancement of therapeutics related to Lymphocyte Activation Gene-3 (LAG-3), and its diversified product portfolio harnesses LAG-3’s ability to stimulate or suppress the immune response. Immutep is dedicated to leveraging its expertise to bring innovative treatment options to patients in need and to maximise value for shareholders. For more information, please visit www.immutep.com.

1. ESMO Congress 2025 Proffered Paper presentation, “EFTISARC-NEO: A phase II study of neoadjuvant eftilagimod alpha, pembrolizumab and radiotherapy in patients with resectable soft tissue sarcoma”.
2. CTOS 2025 Annual Meeting Oral Presentation, “Primary endpoint and translational correlates from EFTISARC-NEO: Phase II trial of neoadjuvant eftilagimod alfa (efti), pembrolizumab and radiotherapy in patients with resectable soft tissue sarcoma”.

KEYTRUDA^® is a registered trademark of Merck Sharp & Dohme LLC, a subsidiary of Merck & Co., Inc., Rahway, NJ, USA.

Australian Investors/Media:
Eleanor Pearson, Sodali & Co.
+61 2 9066 4071; eleanor.pearson@sodali.com

U.S. Investors/Media:
Matthew Beck, astr partners
Ph: +1 (917) 415-1750; matthew.beck@astrpartners.com

This announcement was authorised for release by the CEO of Immutep Limited.

FAQ

AI-generated questions and answers. How Rhea-AI works. Not financial advice.

What does the FDA Orphan Drug Designation mean for Immutep (IMMP) and efti in STS?

ODD grants potential regulatory incentives and exclusivity to support development of efti for STS. According to the company, benefits may include regulatory support, potential tax credits, fee exemptions and seven years of market exclusivity if efti receives approval.

What were the key results from the EFTISARC‑NEO trial cited by Immutep (IMMP)?

The trial reported a median tumour hyalinization/fibrosis of 51.5% in 38 evaluable patients. According to the company, this exceeded the pre‑specified 35% target and historical ~15% with radiotherapy alone, plus showed immune activation and a favourable safety profile.

Does the Orphan Drug Designation mean efti is approved for soft tissue sarcoma?

No, ODD is not an approval and does not guarantee marketing authorization. According to the company, ODD supports development but efti must still complete required trials and regulatory review to gain approval.

How does the discontinuation of the Phase III TACTI‑004 trial affect Immutep (IMMP)?

The company has halted its Phase III TACTI‑004 program and is reviewing options for future trials. According to the company, the outcome of its comprehensive review will influence decisions about potential late‑stage studies with efti.

What safety and surgical timing information did Immutep (IMMP) report for efti in STS?

EFTISARC‑NEO reported a favourable safety profile and no delays to planned surgery. According to the company, translational data also showed immune activation consistent with efti’s mechanism of action.

How many patients were evaluated in the EFTISARC‑NEO trial referenced by Immutep (IMMP)?

The study included 38 evaluable patients in the neoadjuvant setting for resectable STS. According to the company, results were observed across multiple sarcoma subtypes in that cohort.