Following IDMC recommendation after interim futility analysis the decision was made to discontinue the TACTI-004 Phase III trial
Root cause analysis is ongoing and implications for the broader eftilagimod alfa development program are under review
Phase I IMP761 data demonstrates favourable safety profile; trial progressing to multiple ascending dose phase; data expected at EULAR conference in June CY2026
Cash, cash equivalent and term deposit position of A$110.6 million, providing an expected cash reach into H1 CY2028 based on current assumptions.

SYDNEY, AUSTRALIA, April 30, 2026 (GLOBE NEWSWIRE) -- Immutep Limited ((ASX: IMM, NASDAQ:IMMP) ("Immutep" or "the Company"), a clinical-stage biotechnology company targeting cancer and autoimmune diseases, provides an update on its activities for the quarter ended 31 March 2026 (Q3 FY26).

LUNG CANCER

TACTI-004 (KEYNOTE-F91) – Phase III Trial in 1L NSCLC

In March 2026, Immutep announced that the Independent Data Monitoring Committee (IDMC) for the TACTI-004 Phase III study evaluating eftilagimod alfa ("efti") in patients in first-line non-small cell lung cancer (1L NSCLC) had recommended the discontinuation of the trial following a planned interim futility analysis in accordance with the study protocol.

The futility analysis was based on data from approximately 170 patients and included a review of baseline disease characteristics, safety, and overall response rate ("ORR").

After carefully considering the recommendation of the IDMC, as well as conducting its own internal review of the data, Immutep has followed the IDMC's recommendation and decided to discontinue TACTI-004. Notably, Immutep's review included additional data such as early interim progression-free survival data.

More specifically, the Company decided that it was necessary to discontinue TACTI-004 because patients receiving a combination of efti, KEYTRUDA and chemotherapy (the "efti arm") were underperforming relative to patients receiving a combination of placebo, KEYTRUDA and chemotherapy (the "control arm"). This outcome was unexpected, given that efti combined with standard of care has typically produced higher response rates when compared to historical studies or controls. In particular, this outcome was notably inferior to results observed in INSIGHT-003 which was testing the same combinations in non-squamous 1L NSCLC patients.

In response to the IDMC's recommendation, enrolment in TACTI-004 has been halted and Immutep is implementing an orderly wind-down of the study, including appropriate patient follow-up and site close-out in accordance with regulatory and ethical obligations.

While this is a disappointing outcome, it is important to note that this decision relates specifically to TACTI-004 and does not necessarily mean that efti as a broader development program will be discontinued.

Immutep is conducting a thorough review of available data to understand factors behind the futility outcome, examining clinical, operational, analytical, and manufacturing aspects. The process includes collecting and analysing patient samples from TACTI-004 across up to 150 sites and relevant data cleaning. This root cause analysis may extend into Q3 CY2026, depending on data availability and logistics, covering database lock, statistical analysis, and laboratory data review.

Dr. Reddy's Laboratories Ltd. ("Dr. Reddy's"), a key licensing partner for Immutep's efti, continues to demonstrate support and provide technical expertise to assist with the completion of the root cause analysis.

"We continue to work collaboratively with Immutep on the ongoing evaluation of eftilagimod alfa, with a shared focus on determining the appropriate path forward" stated M.V. Ramana, CEO – Global Generics, Dr. Reddy's.

INSIGHT-003 – Phase I Trial in Non-Squamous 1L NSCLC

Patients in the investigator-initiated INSIGHT-003 trial, in which dosing had been completed, continue to be followed up.

In this study, the combination of efti with KEYTRUDA and chemotherapy has generated strong objective response rates (ORR) and disease control rates (DCR) in 51 evaluable patients with advanced or metastatic non-squamous 1L NSCLC across all PD-L1 expression levels.¹

SOFT TISSUE SARCOMA

EFTISARC-NEO – Phase II Trial in Soft Tissue Sarcoma

The investigator-initiated EFTISARC-NEO Phase II trial was evaluating efti with radiotherapy plus KEYTRUDA in the neoadjuvant setting for resectable soft tissue sarcoma (STS).

The study met its primary objective and patients show a strong immune system activation in line with efti's mode of action, with statistically significant increases in the expression of key cytokines and chemokines in peripheral blood — specifically CXCL9, CXCL10, IL-23, and IFN-γ.^2,3 Dosing is completed, and patients are being followed up for disease free survival.

In April 2026, Immutep announced that it had received an orphan drug designation for efti in this setting from the FDA.

BREAST CANCER

AIPAC-003 – Phase II Trial in Metastatic Breast Cancer

Immutep continues to follow up patients in the AIPAC-003 Phase II trial which is evaluating efti in combination with chemotherapy in hormone receptor positive (HR+), HER2-negative/low metastatic breast cancer resistant to endocrine-based therapy or metastatic triple-negative breast cancer not eligible for PD-(L)1-based therapy.

Patients were randomised 1:1 (N=66) to receive either 30 mg or 90 mg efti in combination with chemotherapy to determine the optimal biological dose (OBD) of efti consistent with the FDA's Project Optimus initiative. Dosing is complete, and patients are being followed up for overall survival.

Investigator-Initiated Phase II Trial for Neoadjuvant Efti in HR+/HER2-negative Breast Cancer

A proposed investigator-initiated Phase II trial evaluating neoadjuvant efti as monotherapy and in combination with chemotherapy prior to surgery in early-stage HR+/HER2-negative breast cancer patients is on hold and subject to the root cause analysis related to TACTI-004.

IMP761 DEVELOPMENT PROGRAM FOR AUTOIMMUNE DISEASE

IMP761 – Phase I Trial

In March 2026, Immutep announced an update from the placebo-controlled, double-blind first-in-human Phase I study in healthy participants evaluating IMP761, a first-in-class LAG-3 agonist antibody for autoimmune diseases.

The single ascending portion of the Phase I trial has now been completed, with dosing up to 14 mg/kg and no safety concerns observed. The study is now continuing in the multiple ascending dose (MAD) phase, which is evaluating pharmacokinetics and safety at two dose levels, with completion expected in 3Q CY2026.

The Company will present details on IMP761 at the upcoming EULAR 2026 Congress, which will be held in London, from 3–6 June 2026 and plans to release additional data in 2H CY2026.

INTELLECTUAL PROPERTY

During the quarter, Immutep was granted a new patent in Mexico directed to an assay for use in measuring the potency of IMP761 as part of a quality control step in production of the agonist LAG-3 antibody.

A new Japanese patent was also granted during the quarter directed to LAG525. The patent is co-owned by Immutep S.A.S. and Novartis AG and exclusively licensed to Novartis AG.

FINANCIAL SUMMARY

During the quarter, Immutep continued to exercise prudent cash management, particularly in light of the TACTI-004 Phase III discontinuation.

The Company is well funded with a cash and cash equivalent, and term deposit balance as at 31 March 2026 of approximately A$110.6 million, which is better than the FY2026 budget. However, this cash balance will be reduced by the wind down costs of TACTI-004 and associated activities.

The total balance consists of 1) a cash and cash equivalent balance of A$84.3 million and 2) bank term deposits totaling A$26.3 million, which have been recognised as short-term investments due to having maturities of more than 3 months and less than 12 months.

In Q3 FY26, cash receipts from customers were A$28.85 million, which is mainly due to the US$20 million (A$28.84 million⁴) upfront payment from Dr. Reddy's. The net cash used in G&A activities in the quarter was A$0.9 million compared to A$1.3 million in Q2 FY26.

In respect of the upfront licence fee of US$20 million received from Dr. Reddy's in January 2026, US$2.7million (A$4.1 million⁵) was recognised as revenue and US$17.3 million (A$25.8 million⁶) was recognised as unearned revenue in the Company's Half Year Financial Report for the period ended 31 December 2025.

Following the discontinuation of TACTI‑004, a payment obligation has arisen under the Company's licence agreement with Dr. Reddy's. Under the licence agreement terms, the Company must pay US$10 million to Dr. Reddy's by June 2026 in these circumstances. No payment has been made to Dr. Reddy's at the date of this announcement. The expected payment will result in a cash outflow of US$10 million in the June 2026 quarter and corresponding reduction in unearned revenue. The remaining balance of US$7.3 million in unearned revenue is expected to be recognised as revenue for the half-year ending 30 June 2026.

As previously disclosed, under the terms of the licensing agreement, Dr. Reddy's has the exclusive rights to develop and commercialise efti in the licensed territories; Immutep has an entitlement to potential regulatory, development and commercial milestone payments of up to US$349.5 million; royalties on commercial sales in the licensed territories; and Immutep retains global manufacturing rights and will supply the product to Dr. Reddy's in the licensed markets.

The cash used in R&D activities during the quarter was A$11.8 million, compared to A$9.9 million in Q2 FY26. Payment for staff costs was A$2.6 million in the quarter, remaining the same level as in Q2 FY26. Total net cash inflows from operating activities in the quarter were A$13.5 million compared to net cash outflow of A$9.4 million in Q2 FY26.

Payments to Related Parties comprises Non-Executive Directors' fees and Executive Directors' remuneration of A$515k.

Total net cash inflow received in investing activities for the quarter was A$20k, which is mainly the refund of an office security deposit.

After the TACTI-004 Phase III futility outcome, the Company has started to initiate cost reduction measures to preserve capital and extend its cash runway. These measures include a targeted reduction in headcount and other operating expense reductions. The discontinuation of TACTI-004 also precipitates a reduction in cash outlays due to the trial activity being wound down. At the time of preparing this report, the Company expects its cash runway to extend into H1 of CY28.

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 the Lymphocyte Activation Gene-3 (LAG-3)/MHC Class II immune control mechanism, and its diversified product portfolio harnesses the ability of this mechanism to stimulate or suppress the immune system. 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 Poster Presentation, "Eftilagimod alpha (soluble LAG-3 protein) combined with 1^st line chemo-immunotherapy in metastatic non-squamous non-small cell lung cancer (NSCLC) – Updates from INSIGHT-003 (IKF-s614)".

2. 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".

3. 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".

4. Translated using the March 2026 quarter average AUD/USD exchange rate

5. Translated using December 2025 average AUD/USD exchange rate

6. Translated using 31 December 2025 AUD/USD closing exchange rate

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.

Immutep Quarterly Activities Report Q3 FY26