Systemic immune activation with eftilagimod alfa associated with statistically significant increased overall survival in late-stage cancer patients

SYDNEY, AUSTRALIA, May 28, 2026 (GLOBE NEWSWIRE) --Immutep Limited(ASX: IMM; NASDAQ: IMMP) (“Immutep” or “the Company”), a clinical-stage biotechnology company targeting cancer and autoimmune diseases, today announced results from a systematic evaluation of 5 clinical trials of eftilagimod alfa (“efti”) an antigen-presenting cell (APC) activator in combination with standard-of-care (SOC) therapies in late-stage cancer patients.

In these trials, treatment with 30 mg subcutaneous (SC) efti plus SOC resulted in a significant increase in circulating absolute lymphocyte count (ALC), a blood-based measure of immune activity, compared to SOC alone where this effect was not seen. More importantly, increased ALC was significantly associated with improved clinical outcomes in the E+SOC group. A clinically meaningful and significant median overall survival (OS) improvement (median +7.7 months; p=0.00171) was seen in ALC responders compared to ALC non-responders in the efti + SOC group (figure on the left). No corresponding association between ALC response and OS was observed in the SOC alone group (figure on the right).

The analysis included 5922patients across five independent clinical studies (TACTI-mel, TACTI-002, TACTI-003, AIPAC, AIPAC-003) spanning four cancer indications (NSCLC, HNSCC, MBC, melanoma), correlating the pharmacological effects of efti in combination with SOC treatments with clinical efficacy.

Overall survival of late-stage cancer patients treated with SOC + efti (left) and SOC alone (right), ALC responders vs ALC non-responders.

Effects were observed across the different tumor types and were independent of the combination partner i.e., chemotherapy or immunotherapy such as PD-1 antagonists.

“These findings link the immune-activating effect of efti measured in patients´ blood with meaningful and significant survival improvements observed in previous clinical trials. Importantly, this highlights a key connection between efti´s mechanism of action and clinical efficacy,” said Frederic Triebel, Chief Scientific Officer of Immutep.

In addition, treatment with efti plus SOC was associated with a rapid and significant increase in circulating TH1-related biomarkers, which correlated with clinical response. Gene expression profiling further demonstrated enhanced T-cell function scores in responding patients.

Collectively, these data suggest that efti induced broad immune activation, including circulating immune cells, cytokine responses and gene expression, and that this activation was associated with improved clinical benefit in late-stage cancer patients across multiple tumor types.

The data will be presented in a poster at the 2026 American Society of Clinical Oncology (ASCO) Annual Meeting.

ASCO 2026 Poster Presentation DetailsTitle:Eftilagimod alfa, an APC activator via MHC class II, induced lymphocyte activation linked to improved survival in metastatic cancer patientsPoster Session:Developmental Therapeutics—ImmunotherapyDate and Time:30 May 2026, 1:30 PM-4:30 PM CDTPoster Board:359Abstract #:2569

The poster will be available on the Posters & Publications section ofImmutep’s websitefollowing the presentation.

In March 2026, following a planned interim futility analysis, Immutep discontinued the TACTI-004 Phase III trial in first-line non-small cell lung cancer based on a recommendation from the Independent Data Monitoring Committee, and Immutep continues to review available data to understand factors behind the futility outcome and to evaluate implications for the broader eftilagimod alfa development program.

The data presented in this explorative analysis does not include data from the TACTI-004 study, as immune data collection for that trial had not been completed at the time of the analysis. All data presented were generated from earlier clinical trials.

About ImmutepImmutep Limited (ASX: IMM; NASDAQ: IMMP) is a clinical-stage biotechnology company targeting cancer and autoimmune diseases. The Company is developing novel immunotherapies based on Lymphocyte Activation Gene-3 (LAG-3). For more information, please visitwww.immutep.com.

Forward-Looking StatementsThis press release contains forward-looking statements, including statements regarding anticipated clinical development, regulatory progress and potential benefits of eftilagimod alfa. These forward-looking statements are based on current expectations, estimates and projections, and involve known and unknown risks, uncertainties and other important factors that could cause actual results to differ materially from those expressed or implied in such statements.

Factors that could cause actual results to differ materially include risks associated with clinical trial outcomes, regulatory developments, and the Company’s ability to advance its product candidates.

Readers are cautioned not to place undue reliance on forward-looking statements, which speak only as of the date of this release. Immutep undertakes no obligation to update or revise such statements, except as required by applicable law.

DisclaimerThis announcement has been prepared for informational purposes only and does not constitute an offer to sell, or a solicitation of an offer to buy, securities in any jurisdiction.

1Overall survival was compared using Kaplan-Meier estimates and a log-rank test.2Details of the analysis are described on the poster in the methods section.