Exhibit 99.1

ASX/Media Release

Immutep Quarterly Activities Report & Appendix 4C

Q3 FY25

SYDNEY, AUSTRALIA – 29 April 2025 – Immutep Limited (ASX: IMM; NASDAQ: IMMP) (“Immutep” or “the Company”), a clinical-stage biotechnology company developing novel LAG-3 immunotherapies for cancer and autoimmune disease, provides an update on its activities for the quarter ended 31 March 2025 (Q3 FY25).

EFTI DEVELOPMENT PROGRAM FOR CANCER

TACTI-004 – First Patient Successfully Dosed in Pivotal Phase III Trial in 1L NSCLC

In March 2025, Immutep announced the first patient in the Company’s pivotal TACTI-004 Phase III trial was successfully dosed at Calvary Mater Newcastle Hospital in Australia. TACTI-004 evaluates eftilagimod alfa (efti), a first-in-class MHC Class II agonist, in combination with MSD’s (Merck & Co., Inc., Rahway, NJ, USA) anti-PD-1 therapy KEYTRUDA® (pembrolizumab) and chemotherapy as first line treatment of patients with advanced or metastatic non-small cell lung cancer (1L NSCLC). The global Phase III trial with efti will randomize approximately 756 patients at more than 150 clinical sites and trial results will inform a potential marketing approval application in non-small cell lung cancer, one of the largest indications in oncology.

Immutep also presented the pivotal TACTI-004 Phase III trial as a Trial-in-Progress poster at the European Lung Cancer Congress (ELCC) 2025, in Paris, France, in late March. The poster included an overview and study design of the TACTI-004 Phase III trial. Informed by the Company’s AIPAC-003 study, Immutep has determined to move forward with 30 mg efti dosing as the optimal biological dose. We have observed encouraging support from the investigators participating in the study in our meetings to date including those held at ELCC 2025 and after quarter end at the investigator meeting in Budapest, Hungary. Consistent feedback has been that the efficacy and safety data collected thus far from the TACTI-002 and INSIGHT-003 trials are impressive and address the unmet medical needs seen by many key opinion leaders.

Recruitment in TACTI-004 is underway at a growing number of activated clinical sites and countries with approvals from regulatory authorities expanded to now 19 countries including Australia, Austria, Belgium, Bulgaria, Canada, Germany, Greece, Hungary, India, Ireland, Italy, Latvia, Lithuania, Portugal, Spain, and the United Kingdom.

TACTI-003 (KEYNOTE-C34) – Phase IIb Trial in 1L HNSCC

Immutep continued to follow patients in the TACTI-003 (KEYNOTE-C34) Phase IIb trial, which is evaluating efti in combination with MSD’s anti-PD-1 therapy KEYTRUDA® (pembrolizumab) as first-line treatment of recurrent or metastatic head and neck squamous cell carcinoma (1L HNSCC), during Q3 FY25. Immutep most recently reported positive results from Cohort B of the trial in 1L HNSCC patients with PD-L1 negative tumours (CPS <1) who typically do not respond well to anti-PD-1 therapy alone, at the ESMO Immuno-Oncology Annual Congress in December 2024. Immutep will continue to follow the maturing data from TACTI-003 and plans to engage with regulatory authorities regarding potential paths forward by mid of this year.

AIPAC-003 – Phase II/III Trial in Metastatic Breast Cancer

Immutep continues to execute the AIPAC-003 trial, which enrolled 71 metastatic hormone receptor positive (HR+), HER2-negative/low or triple-negative breast cancer patients who exhausted endocrine therapy including cyclin-dependent kinase 4/6 (CDK4/6) inhibitors. Immutep completed patient enrolment in the randomised Phase II portion of the AIPAC-003 trial in late 2024. Patients across 22 clinical sites in Europe and the United States have been randomised 1:1 to receive either 30mg or 90mg dosing of efti in combination with paclitaxel to determine the optimal biological dose consistent with the FDA’s Project Optimus initiative and prior regulatory interaction with FDA. Patient follow up, data cleaning and analysis is ongoing and an update is anticipated in CY2025.

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

In January 2025, Immutep announced that patient enrolment has been completed for the ongoing investigator-initiated INSIGHT-003 trial. INSIGHT-003 is evaluating efti in combination with the anti-PD-1 therapy, KEYTRUDA® (pembrolizumab) and doublet chemotherapy as first line treatment of patients with advanced or metastatic non-squamous non-small cell lung cancer (1L NSCLC). The Phase I trial has reached its enrolment target of approximately 50 evaluable patients across multiple clinical sites in Germany led by the Frankfurt Institute of Clinical Cancer Research IKF.

Positive first Overall Survival results and other data points from INSIGHT-003 were reported in late 2024. Data updates from INSIGHT-003 are expected in CY2025.

EFTISARC-NEO – Phase II Trial in Soft Tissue Sarcoma

In January 2025, Immutep announced that patient enrolment has been completed in the ongoing investigator-initiated EFTISARC-NEO trial. EFTISARC-NEO is evaluating efti in combination with radiotherapy plus KEYTRUDA® (pembrolizumab) in the neoadjuvant setting for patients with resectable soft tissue sarcoma (STS). The Phase II trial being conducted by the Maria Skłodowska-Curie National Research Institute of Oncology (MSCNRIO) in Warsaw, the national reference centre for STS in Poland, reached its enrolment target of 40 patients.

Encouraging data from EFTISARC-NEO was presented at the Connective Tissue Oncology Society (CTOS) Annual Meeting in November 2024. Data updates from EFTISARC-NEO are expected in CY2025.

IMP761 DEVELOPMENT PROGRAM FOR AUTOIMMUNE DISEASE

Immutep is progressing with the ongoing Phase I trial of its autoimmune candidate IMP761. IMP761 is a first-in-class agonist LAG-3 antibody designed to restore balance to the immune system by enhancing the “brake” function of LAG-3 to silence dysregulated self-antigen-specific memory T cells that cause many autoimmune diseases. Following previously reported favourable initial safety data in December 2024, additional safety data and assessment of pharmacokinetic/pharmacodynamic (PK/PD) relationships are expected to be reported in CY2025.

INTELLECTUAL PROPERTY

During the quarter, Immutep was granted two new patents for LAG525 in in the Philippines and the United States. Immutep was also granted a Russian patent directed to an assay for use in measuring the potency of IMP761, for example, as part of a quality control step in production of the agonist LAG-3 antibody.

CASH FLOW SUMMARY

During the quarter, Immutep continued to advance its clinical trial programs for efti and for IMP761 with prudent cash management. The Company is well funded with a strong cash and cash equivalent, and term deposit balance as at 31 March 2025 of approximately A$146.25 million, which is greater than budgeted as at the beginning of the current financial year, whilst delivering on our announced goals. The total balance consists of: 1) a cash and cash equivalent balance of A$92.45 million and 2) bank term deposits totaling A$53.80 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 FY25, cash receipts from customers were A$12k. The net cash used in G&A activities in the quarter was A$704k, compared to A$566k in Q2 FY25. Payments to Related Parties (detailed in item 6.1 of the Appendix 4C) comprises Non-Executive Directors’ fees and Executive Directors’ remuneration of A$363k.

The net cash used in R&D activities during the quarter was A$13.6 million, compared to A$16.2 million in Q2 FY25. The decrease is mainly due to:

Payment for staff costs was A$2.5 million in the quarter, which was the same as for Q2 FY25.

Total net cash outflows used in operating activities in the quarter were A$16.26 million compared to A$19.0 million in Q2 FY25.

Total cash inflow from investing activities for the quarter was A$32.34 million, mainly due to the maturity of short-term investments. The short-term investments are comprised of term deposits with maturities of greater than 3 months and less than 12 months. During the quarter, the company transferred back A$32.34 million from short-term investments that had matured to cash at bank, resulting in a positive cashflow in investing activities.

A copy of the Appendix 4C - Quarterly Cash Flow Report for the quarter is attached.

About Immutep

Immutep is a clinical-stage biotechnology company developing novel LAG-3 immunotherapy for cancer and autoimmune disease. We are pioneers in the understanding and advancement of therapeutics related to Lymphocyte Activation Gene-3 (LAG-3), and our diversified product portfolio harnesses its unique 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.

Australian Investors/Media:

Catherine Strong, Sodali & Co

+61 (0)406 759 268; catherine.strong@sodali.com

U.S. Investors/Media:

Chris Basta, VP, Investor Relations and Corporate Communications

+1 (631) 318 4000; chris.basta@immutep.com

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

Immutep Limited, Level 32, Australia Square, 264 George Street, Sydney NSW 2000, Australia

ABN: 90 009 237 889

Rule 4.7B

Appendix 4C

Quarterly cash flow report for entities

subject to Listing Rule 4.7B

Appendix 4C

Quarterly cash flow report for entities subject to Listing Rule 4.7B

Appendix 4C

Quarterly cash flow report for entities subject to Listing Rule 4.7B

Note: if any amounts are shown in items 6.1 or 6.2, your quarterly activity report must include a description of, and an explanation for, such payments.

The amount at 6.1 includes payment of Non-Executive Directors’ fees and Executive Directors’ remuneration.

Appendix 4C

Quarterly cash flow report for entities subject to Listing Rule 4.7B

Appendix 4C

Quarterly cash flow report for entities subject to Listing Rule 4.7B

Compliance statement

Notes