Immutep s Efti with KEYTRUDA (pembrolizumab) & Chemotherapy Achieves High Response Rates in First-Line Non-Small Cell Lung Cancer Novel combination achieves 60.8% response rate and 90.2% disease control rate in first-lin

Immutep s Efti with KEYTRUDA (pembrolizumab) & Chemotherapy

Achieves High Response Rates in First-Line Non-Small Cell Lung Cancer

SYDNEY, AUSTRALIA May 15, 2025 Immutep Limited (ASX:

IMM; NASDAQ: IMMP) ( Immutep or the Company ), a late-stage immunotherapy company targeting cancer and autoimmune diseases, today announces that a 60.8% response rate and 90.2% disease control rate, according to RECIST1.1, has

been achieved in the investigator-initiated INSIGHT-003 trial as of the data-cut off date of 06 May 2025. INSIGHT-003 is evaluating eftilagimod alpha (efti) in

combination with the anti-PD-1 therapy, KEYTRUDA (pembrolizumab) and doublet chemotherapy as first-line

treatment for patients with advanced or metastatic non-squamous non-small cell lung cancer (1L NSCLC).

Marc Voigt, CEO of Immutep, stated, Our level of confidence in efti driving a new standard of care for patients with non-small cell lung cancer via our pivotal TACTI-004 trial continues to rise with the strength of the data from INSIGHT-003 and TACTI-002. Across two trials we have now efficacy data from 165 patients with 1L NSCLC who have been treated with efti and KEYTRUDA, either with or without chemotherapy. In multi-national settings, efti has

generated consistent and remarkable improvements in response rates. In particular, the interim ORR data in patients with PD-L1 expression below 50% in the ongoing

INSIGHT-003 trial, who represent over two-thirds of the 1L NSCLC patient population, is very encouraging.

Majority of Patients have PD-L1 TPS <50%

Notably, ~92% of all evaluable patients (N=51) in the INSIGHT-003 study have

PD-L1 TPS <50%. This includes 49% of patients with PD-L1 Tumour Proportion Score (TPS) of 1-49% and 43% of patients with PD-L1 TPS <1%, as shown in the table below.

Strong Response Rates Across All

PD-L1 Expression Levels

Data from all evaluable patients demonstrates significant improvement of Overall

Response Rate (ORR) according to RECIST 1.1 across all levels of PD-L1 expression compared to historical control from a registrational trial of

anti-PD-1 and doublet chemotherapy in non-squamous 1L NSCLC1:

The 60.8% response rate regardless of PD-L1 expression (TPS 0-100%) represents a substantial improvement compared to historical control of 48.0%.1 The relative outperformance is particularly strong given the

registrational trial has four times as many patients with high PD-L1 expression (~32% of patients versus ~8% in INSIGHT-003), who have the highest response rates.

Importantly, in patients with TPS <50% (N=47), who have a high unmet need and represent over two-thirds of the 1L NSCLC patient populaton, the triple combination with efti achieved a 59.6% response rate as compared to historical control of 40.8%.1

to be favourable for the triple combination in 1L NSCLC with no new safety signals.

Additional data updates from this trial are expected to be presented at a medical conference in 2025 and beyond.

INSIGHT-003 is an investigator-initiated study conducted by the Frankfurt Institute of Clinical Cancer Research

IKF and several other German centres. It is being run as the third arm (Stratum C) of the ongoing Phase I INSIGHT trial with Prof. Dr. Salah-Eddin Al-Batran as lead investigator. The study is evaluating a triple combination therapy in

front-line non-small cell lung cancer patients consisting of efti administered subcutaneously in conjunction with an existing approved

standard-of-care combination of anti-PD-1 therapy (pembrolizumab) and chemotherapy

(carboplatin and pemetrexed) delivered intravenously. The trial will assess the safety, tolerability, and initial efficacy of the combination.

Eftilagimod Alfa (efti)

Efti is Immutep s proprietary soluble LAG-3 protein and MHC Class II agonist

that stimulates both innate and adaptive immunity for the treatment of cancer. As a first-in-class antigen presenting cell (APC) activator, efti binds to MHC (major

histocompatibility complex) Class II molecules on APC leading to activation and proliferation of CD8+ cytotoxic T cells, CD4+ helper T cells, dendritic cells, NK cells, and monocytes. It also upregulates the expression of key biological

molecules like IFN- and CXCL10 that further boost the immune system s ability to fight cancer.

under evaluation for a variety of solid tumours including non-small cell lung cancer (NSCLC), head and neck squamous cell carcinoma (HNSCC), and metastatic breast cancer. Its favourable safety profile enables

various combinations, including with anti-PD-[L]1 immunotherapy and/or chemotherapy. Efti has received Fast Track designation in first line HNSCC and in first line NSCLC

from the United States Food and Drug Administration (FDA).

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:

Catherine Strong, Sodali & Co.

Chris Basta, VP, Investor Relations and Corporate Communications

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

announcement was authorised for release by the Board of Immutep Limited.

Immutep Limited, Level 32, Australia Square, 264

George Street, Sydney NSW 2000, Australia