Immutep Announces Compelling Clinical Results from Phase II Trial Utilizing its First-in-Class Soluble LAG-3 Protein Eftilagimod Alpha in 1st Line NSCLC at SITC 2022 Annual Meeting

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, today announces compelling new clinical data from the TACTI-002 all-comer PD-L1 Phase II trial evaluating Immutep's lead product candidate, eftilagimod alpha ('efti' or 'IMP321') in combination with MSD's (Merck & Co., Inc., Rahway, NJ., USA) anti-PD-1 therapy KEYTRUDA (pembrolizumab) in 114 patients with 1L NSCLC.

The new data was presented today in a late-breaking abstract oral presentation (Abstract 1470) at the 37th Annual Society of Immunotherapy of Cancer (SITC) Meeting by Wade T. Iams, MD, Assistant Professor of Medicine, Vanderbilt-Ingram Cancer Center Division of Hematology/Oncology. Today's presentation followed the abstract data that had been discussed at the SITC 2022 Press Conference on 8 November 2022.

Dr. Iams stated, 'The encouraging ORR, PFS and DCR presented today at SITC build on the promise of efti, a first-in-class soluble LAG-3 protein, to uniquely engage the innate and adaptive immune system to enhance the clinical effect of pembrolizumab. Responses in TACTI-002 were seen across all PD-L1 expression levels and histologic types, including in patients with PD-L1 TPS less than 50%. The deep and durable responses driven by efti plus pembrolizumab continue to be favorable with median DoR of 21.6 months.'

Immutep CSO and CMO, Dr Frederic Triebel, noted, 'The strengthening of efficacy, with improving overall response rates across all levels of PD-L1 stratification in first-line NSCLC patients, with no new safety signals, is quite encouraging. We are pleased to see ORR reach 40.4%, which compares favourably to the approximate 20% response rates in other PD-L1 all-comer trials utilizing anti-PD-1 monotherapy. Importantly, this additional clinical benefit is occurring with a safety profile consistent with that observed in previously reported studies for pembrolizumab monotherapy. We are also excited to share the first pharmacodynamic data from efti's combination with pembrolizumab, showing significant elevation of IFN- and the CXCL10 chemokine serum biomarkers for systemic TH1 response. Similar to the immune response biomarker data seen in efti's randomized Phase IIb trial in breast cancer, this further substantiates efti's novel ability to engage and activate the immune system.'

Immutep CEO Marc Voigt added, 'We are pleased to see patient outcomes improving yet again, and continue to believe that efti, with its unique mechanism of action targeting a subset of MHC class II molecules to mediate antigen-presenting cell activation, holds significant potential to benefit cancer patients. This includes those with PD-L1 expression levels below 50% that represent the vast majority of patients with NSCLC. Based on this compelling data in this large Phase II trial, coupled with the large market opportunity and high unmet need for more durable and tolerable options, we continue to push forward with our late-stage clinical development plans in frontline NSCLC in combination with anti-PD-1 therapy.'

About Eftilagimod Alpha (Efti) Efti is Immutep's proprietary soluble LAG-3 clinical stage candidate that is a first-in-class antigen presenting cell (APC) activator for the treatment of cancer, capitalising on LAG-3's unique characteristics to stimulate both innate and adaptive immunity. Efti binds to and activates antigen presenting cells via MHC II molecules leading to expansion 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 CXCL10 that further boost the immune system's ability to fight cancer.

Efti is under evaluation for a variety of solid tumours including non-small cell lung cancer (NSCLC), head and neck squamous cell carcinoma (HNSCC), and HER2-/HR+ 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 1st line HNSCC and in 1st line NSCLC from the United States Food and Drug Administration (FDA).

About the TACTI-002 Trial TACTI-002 (Two ACTive Immunotherapies) is being conducted in collaboration with Merck & Co., Inc., Rahway, NJ, USA (known as 'MSD' outside the United States and Canada). The study is evaluating the combination of eftilagimod alpha (efti) with MSD's anti-PD-1 therapy KEYTRUDA (pembrolizumab) in patients with second line head and neck squamous cell carcinoma or non-small cell lung cancer in first and second line.

The trial is a Phase II, Simon's two-stage, non-comparative, open-label, single-arm, multicentre clinical study that is taking place in study centres across Australia, Europe, and the US.

Patients participate in one of the following: Part A - first line Non-Small Cell Lung Cancer (NSCLC), PD-X naive Part B - second line NSCLC, PD-X refractory Part C - second line Head and Neck Squamous Cell Carcinoma (HNSCC), PD-X naive

TACTI-002 is an all-comer study in terms of PD-L1 status, a well-known predictive marker for response to pembrolizumab monotherapy especially in NSCLC and HNSCC. More information about the trial can be found on Immutep's website or on ClinicalTrials.gov (Identifier: NCT03625323).

About Immutep Immutep is a clinical stage biotechnology company leading the development of LAG-3 related immunotherapy products for the treatment of cancer and autoimmune disease. The Company is dedicated to leveraging its technology and expertise to bring innovative treatment options to market for patients and to maximise value to shareholders.

Immutep's lead product candidate is eftilagimod alpha ('efti' or 'IMP321'), a soluble LAG-3 fusion protein (LAG-3Ig), which is a first-in-class antigen presenting cell (APC) activator being explored in cancer in multiple clinical trials. The Company is also developing an agonist of LAG-3 (IMP761) for autoimmune disease. Additional LAG-3 product candidates, including antibodies for immune response modulation, are licensed to and being developed by Immutep's large pharmaceutical partners.

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