Immutep to Present New Data from AIPAC-003 Phase II at the 2025 San Antonio Breast Cancer Symposium

Rhea-AI Summary

Immutep (NASDAQ: IMMP) will present Phase II AIPAC-003 data at SABCS 2025 showing the immunotherapy-chemotherapy combination of eftilagimod alfa (efti) plus paclitaxel produced strong responses and immune activation in heavily pretreated metastatic breast cancer patients.

In the evaluable population (N=64) ORR/DCR were 41.9%/87.1% (30 mg) and 48.5%/78.8% (90 mg); time to response was ~2.0 months. FDA Project Optimus requirements were satisfied and 30 mg was selected as efti’s optimal biological dose (OBD) after tolerability issues at 90 mg.

Positive

• Objective response rate 41.9% at 30 mg
• Disease control rate 87.1% at 30 mg
• Objective response rate 48.5% at 90 mg
• Project Optimus completion and 30 mg OBD selection
• Immune activation shown by increases in ALC and IFN-γ

Negative

• Tolerability suboptimal at 90 mg including dose-limiting toxicities
• Higher proportion of local injection site reactions at 90 mg

News Market Reaction

-7.07%

10 alerts

-7.07% News Effect

-9.2% Trough in 24 hr 10 min

-$21M Valuation Impact

$271M Market Cap

1.3x Rel. Volume

On the day this news was published, IMMP declined 7.07%, reflecting a notable negative market reaction. Argus tracked a trough of -9.2% from its starting point during tracking. Our momentum scanner triggered 10 alerts that day, indicating notable trading interest and price volatility. This price movement removed approximately $21M from the company's valuation, bringing the market cap to $271M at that time.

Data tracked by StockTitan Argus on the day of publication.

Key Figures

Participants: 66 patients Evaluable patients: 64 patients ORR (30 mg): 41.9% +5 more

8 metrics

Participants 66 patients Randomised Phase II AIPAC-003 metastatic breast cancer trial

Evaluable patients 64 patients AIPAC-003 evaluable population for efficacy analysis

ORR (30 mg) 41.9% Objective response rate with 30 mg efti plus paclitaxel

DCR (30 mg) 87.1% Disease control rate with 30 mg efti plus paclitaxel

ORR (90 mg) 48.5% Objective response rate with 90 mg efti plus paclitaxel

DCR (90 mg) 78.8% Disease control rate with 90 mg efti plus paclitaxel

Time to response (30 mg) 2.0 months Median time to onset of response with 30 mg efti

Time to response (90 mg) 1.9 months Median time to onset of response with 90 mg efti

Market Reality Check

Price: $3.17 Vol: Volume 717,346 is below t...

low vol

$3.17 Last Close

Volume Volume 717,346 is below the 20-day average of 1,684,778 (relative volume 0.43x). low

Technical Price at 2.63 is trading above the 200-day MA of 1.78, indicating a pre-existing upward trend.

Peers on Argus

IMMP gained 11.11% while the only peer in the momentum scan (ACIU) moved down; o...

1 Down

IMMP gained 11.11% while the only peer in the momentum scan (ACIU) moved down; other biotech peers showed mixed, mostly modest moves, suggesting a stock-specific reaction.

Common Catalyst Clinical-trial news featured in the sector, but IMMP’s move appears more company-specific than broad biotech rotation.

Historical Context

5 past events · Latest: Dec 08 (Positive)

Pattern 5 events

Date	Event	Sentiment	Move	Catalyst
Dec 08	Licensing partnership	Positive	+26.1%	Global efti collaboration with Dr. Reddy’s including upfront and milestones.
Dec 02	Clinical data update	Positive	-7.1%	AIPAC-003 Phase II data with strong responses and 30 mg OBD selection.
Nov 13	Clinical data update	Positive	+2.8%	EFTISARC-NEO Phase II met primary endpoint with robust translational signals.
Nov 03	Tax incentive cash	Positive	-3.2%	Receipt of French R&D tax incentive to support ongoing development.
Oct 29	Quarterly update	Positive	-1.0%	Q1 FY26 report highlighting TACTI-004 progress and cash of <b>A$109.85M</b>.

Pattern Detected

Recent history shows more divergences than alignments, with several positive updates followed by negative or muted price reactions.

Recent Company History

Over the past few months, Immutep reported multiple milestones, including positive Phase II data in soft tissue sarcoma, a sizeable R&D tax incentive, and progress updates on its Phase III TACTI-004 NSCLC trial, plus a major efti out-licensing deal with Dr. Reddy’s. The AIPAC-003 SABCS presentation continues this pattern of clinically oriented news. Price reactions have been mixed, with some strong gains like the Dec 8 partnership and several instances where favorable news coincided with share price declines.

Market Pulse Summary

The stock moved -7.1% in the session following this news. A negative reaction despite positive AIPAC...

Analysis

The stock moved -7.1% in the session following this news. A negative reaction despite positive AIPAC-003 data would fit the pattern of past divergences, where favorable updates sometimes coincided with selling pressure. The trial mainly refines dosing and supports immune-activation biology rather than providing registrational data, so some investors may have reassessed risk-reward. Given prior instances where good clinical or financial news led to declines, future durability would likely hinge on larger, late-stage outcomes and execution in NSCLC.

Key Terms

objective response rates, disease control rates, pharmacodynamic, biomarkers, +4 more

8 terms

objective response rates medical

"led to strong objective response rates and immune activation in heavily pretreated"

Objective response rate (ORR) is the share of patients in a clinical trial whose disease shows a clear, measurable improvement—usually tumor shrinkage or disappearance—based on predefined criteria. For investors, ORR offers a concrete early signal of a therapy’s effectiveness: higher ORR can increase the drug’s chance of regulatory approval, commercial value, and revenue potential, much like a product’s percent of satisfied customers predicting market success.

disease control rates medical

"led to strong objective response rates (ORR) and disease control rates (DCR) of 41.9%"

Disease control rate (DCR) is the percentage of patients in a clinical study whose disease either shrinks or remains stable for a predefined period after treatment, combining responses like tumor reduction and stable disease into one measure. For investors, DCR offers a quick snapshot of a therapy’s ability to halt progression — like noting how many storms a treatment has calmed — and can signal commercial potential and regulatory interest when assessing drug programs.

pharmacodynamic medical

"elicited the desired pharmacodynamic (PD) response in line with efti’s mechanism"

Pharmacodynamic describes how a drug acts on the body — the biological effects it produces, how strong those effects are, and how long they last. For investors, pharmacodynamic data show whether a treatment actually works and at what dose, shaping expectations about a drug’s safety, effectiveness, regulatory success and market potential; think of it like testing how well a key turns a lock and whether it reliably opens the door.

biomarkers medical

"substantial increases in immune activation biomarkers including absolute-lymphocyte count"

Biomarkers are measurable indicators found in the body, such as substances in blood or tissues, that reveal information about health or disease. For investors, they can signal how well a medical treatment is working or whether a disease is developing, helping to assess the potential success or risks of healthcare companies or innovations. Think of biomarkers as biological signals that provide clues about a person’s health status.

absolute-lymphocyte count medical

"immune activation biomarkers including absolute-lymphocyte count (ALC) and interferon-gamma"

Absolute lymphocyte count is a blood test that measures the actual number of lymphocytes — the white blood cells that help fight infections and regulate the immune system — in a given volume of blood. Investors watch it because changes can signal how a patient population is responding to a therapy, reveal safety issues (like immune suppression), affect clinical trial outcomes or regulatory decisions, and therefore influence a company’s valuation or market outlook.

interferon-gamma medical

"absolute-lymphocyte count (ALC) and interferon-gamma (IFN-γ). Data cut-off date"

Interferon-gamma is an immune signaling protein produced by certain white blood cells that helps coordinate the body’s defense against infections and abnormal cells; think of it as a coach that tells other immune cells when and how to act. It matters to investors because drugs, diagnostics, or safety findings involving interferon-gamma can change clinical trial results, regulatory decisions, and market potential for therapies, which in turn can affect a company’s valuation and stock performance.

dose-limiting toxicities medical

"Tolerability at 90 mg was suboptimal including dose-limiting toxicities (DLT)"

Dose-limiting toxicities are the harmful side effects seen in early clinical trials that are severe enough to stop researchers from raising a drug’s dose. Like a car’s speed limiter marking the safe top speed, DLTs define the maximum tolerable dose, and they matter to investors because they determine whether a medicine can reach effective levels, influence development timelines, costs, and regulatory chances, and thus affect a drug’s commercial prospects.

non-small cell lung cancer medical

"Phase III trial evaluating efti in combination with MSD’s anti-PD-1 therapy KEYTRUDA"

A broad category of lung tumors that grow from the cells lining the airways and make up the majority of lung cancer cases; it includes several subtypes that behave and respond to treatment differently, like different models of the same car family. It matters to investors because its large patient population and variety of treatment options — surgery, traditional chemo, targeted drugs and immunotherapies — create major markets where clinical trial results, drug approvals or changing treatment guidelines can quickly affect a company’s revenue and stock value.

AI-generated analysis. Not financial advice.

• Immunotherapy-chemotherapy combination of eftilagimod alfa (efti) and paclitaxel led to strong objective response rates and immune activation in heavily pretreated metastatic breast cancer patients
• AIPAC-003 has resulted in successful completion of FDA’s Project Optimus requirements and selection of 30 mg as efti’s optimal biological dose

SYDNEY, AUSTRALIA, Dec. 02, 2025 (GLOBE NEWSWIRE) -- Immutep Limited (ASX: IMM; NASDAQ: IMMP) (“Immutep” or “the Company”), a late-stage immunotherapy company targeting cancer and autoimmune diseases, today announces new data from the AIPAC-003 trial will be presented at the 2025 San Antonio Breast Cancer Symposium (SABCS) taking place in San Antonio, Texas, from December 9-12, 2025.

The Phase II study randomised female participants (N=66) with HR+ and HER2-negative/HER2-low metastatic breast cancer (MBC) resistant to endocrine-based therapy (ET) including cyclin-dependent kinase 4/6 (CDK4/6) inhibitors or metastatic triple-negative breast cancer (mTNBC) not eligible for PD-(L)1-based therapy. Patients were randomised 1:1 to receive either 30 or 90 mg eftilagimod alfa (efti) in combination with paclitaxel to determine the optimal biological dose (OBD) consistent with the FDA’s Project Optimus initiative.

Both efti dosing levels on top of weekly paclitaxel in heavily pretreated metastatic breast cancer patients, who received a median of three prior lines of systemic therapy, led to strong objective response rates (ORR) and disease control rates (DCR) of 41.9% and 87.1% (30 mg efti) and 48.5% and 78.8% (90 mg efti), respectively, in the evaluable population (N=64). Time to onset of response (TTR) was comparable at 2.0 months (30 mg) versus 1.9 months (90 mg).

Additionally, both dosing levels elicited the desired pharmacodynamic (PD) response in line with efti’s mechanism of action with substantial increases in immune activation biomarkers including absolute-lymphocyte count (ALC) and interferon-gamma (IFN-γ). Data cut-off date for efficacy results was 15 September 2025.

Dr. Nuhad Ibrahim, Professor, Department of Breast Medical Oncology, Division of Cancer Medicine, The University of Texas MD Anderson Cancer Center noted, “Evaluating two biologically active doses allowed us to integrate clinical response data with meaningful pharmacodynamic readouts. In keeping with Project Optimus principles, the study generated rigorous comparative data in heavily pretreated metastatic breast cancer patients showing consistent efficacy measures and immune-activation signals across both arms, reinforcing efti’s novel mechanism of action and the clinical potential of this immunotherapy-chemo combination.”

Tolerability at 90 mg was suboptimal including dose-limiting toxicities (DLT) and a higher proportion of local injection site reactions (LISR). In line with FDA guidance/advice and as previously reported on 13 October 2025, 30 mg of efti administered subcutaneously has been defined as the OBD.

Marc Voigt, CEO of Immutep said, “We are pleased to conclude this important phase of efti’s clinical development and are fully committed to advancing this novel immunotherapy to address the needs of cancer patients globally, especially in light of our ongoing Phase III in 1^st line NSCLC. This study holds significant importance in satisfying FDA’s Project Optimus requirements and defining efti’s OBD across our entire oncology clinical pipeline and potential future combinations with new therapeutic agents such as ADCs and bispecifics as well as for a potential future Biological Licence Application.”

The AIPAC-003 trial has resulted in the successful completion of the FDA’s Project Optimus requirements and agreement on 30 mg as efti’s OBD carries strategic importance in ongoing and future clinical programs in oncology. This includes the global TACTI-004 (KEYNOTE-F91) Phase III trial evaluating efti in combination with MSD’s (Merck & Co., Inc., Rahway, NJ, USA) anti-PD-1 therapy KEYTRUDA^® (pembrolizumab), and chemotherapy as first-line treatment for advanced or metastatic non-small cell lung cancer (1L NSCLC), regardless of PD-L1 expression, which is now in the process of opening sites in the United States.

Details on the SABCS 2025 presentation are as follows:

Title: Optimal biological dose of eftilagimod alpha, a soluble LAG-3 protein, in metastatic breast cancer patients receiving weekly paclitaxel in AIPAC-003
Presenter: Dr. Nuhad Ibrahim, Professor, Department of Breast Medical Oncology, Division of Cancer Medicine, The University of Texas MD Anderson Cancer Center
Presentation number: PS1-09-16
Abstract number: 315
Date and time: Wednesday, December 10^th at 12:30-2:30 p.m. CST

The poster presentation is available on the Posters & Publications section of Immutep’s website.

About Immutep
Immutep is a late-stage biotechnology company developing novel immunotherapies for cancer and autoimmune disease. 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.

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:
Chris Basta, VP, Investor Relations and Corporate Communications
+1 (631) 318 4000; chris.basta@immutep.com

FAQ

What AIPAC-003 efficacy did Immutep report for IMMP at SABCS 2025?

In the evaluable population (N=64) ORR was 41.9% (30 mg) and 48.5% (90 mg); DCR was 87.1% (30 mg) and 78.8% (90 mg).

What dose did FDA Project Optimus determine as efti’s OBD for IMMP?

Following AIPAC-003 and FDA guidance, 30 mg subcutaneous efti was selected as the optimal biological dose.

When and where will Immutep (IMMP) present AIPAC-003 data?

Presentation at SABCS 2025 on December 10, 2025, 12:30–2:30 p.m. CST (poster PS1-09-16, abstract 315).

How quickly did patients respond to efti plus paclitaxel in AIPAC-003?

Time to onset of response was comparable: 2.0 months (30 mg) and 1.9 months (90 mg).

Did AIPAC-003 show immune activation for efti in IMMP’s results?

Yes; both doses showed pharmacodynamic immune activation including rises in ALC and IFN-γ.

What safety concerns were reported for efti at 90 mg in AIPAC-003?

Tolerability at 90 mg was suboptimal with reported dose-limiting toxicities and more local injection site reactions.

How does AIPAC-003 impact Immutep’s oncology programs for IMMP?

Completion of Project Optimus and 30 mg OBD carry strategic importance for ongoing and future trials including the global Phase III TACTI-004 (KEYNOTE-F91).