Immutep Announces Improving Data from the Phase II TACTI-002 Study

Presented at ASCO 2020 Annual Meeting

• First complete response reported in 2^nd line head and neck squamous cell carcinoma (HNSCC)
• Improving Overall Response Rate (iORR) in HNSCC, increasing to 38.9% (previously 33% iORR)
• Progression free survival (PFS) continues to improve in 1^st line non-small cell lung cancer (NSCLC) patients, estimated at more than 9 months

SYDNEY, Australia, June 01, 2020 (GLOBE NEWSWIRE) -- Immutep Limited (IMMIMMP announces new interim data from its ongoing Phase II TACTI-002 study. This data relates to the cut-off date of 4 May 2020 and shows improving efficacy results. The results were presented as a poster short talk by trial investigator, Dr Enriqueta Felip, of Vall d'Hebron University Hospital in Barcelona, Spain, at the 2020 American Society of Clinical Oncology (ASCO) Virtual Annual Meeting. The poster presentation from Dr. Felip is available on the company's website (click here).  

TACTI-002 is being conducted in collaboration with Merck & Co., Inc., Kenilworth, NJ, USA (known as "MSD" outside the United States and Canada). The study is evaluating the combination of the Company's lead product candidate eftilagimod alpha ("efti" or "IMP321") with MSD's KEYTRUDA® (pembrolizumab) in up to 109 patients with second line Head and Neck Squamous Cell Carcinoma (HNSCC) or Non-Small Cell Lung Cancer (NSCLC) in first and second line.

Immutep CSO and CMO, Dr Frederic Triebel said: "TACTI-002 is generating increasingly promising data from both the NSCLC and HNSCC arms of study, as patients continue to receive efti in combination with KEYTRUDA. Remarkably, one HNSCC patient has even achieved a complete response, bringing the total response rate to an improved 39% in this arm. This is an early indication that the efti in combination with pembrolizumab may more than double the proportion of HNSCC patients that respond to pembrolizumab monotherapy, which is usually 18% or less¹."

Trial investigator, Dr. Felip said: "It is encouraging to see that patients continue to receive benefit from the combination treatment. We now expect progression free survival to be more than 9 months for patients with 1^st line NSCLC, significantly longer than the 5-6 months delivered by pembrolizumab monotherapy. We are alo seeing deeper responses in both arms with patients responding after a number of months of treatment.  The improving data in both HNSCC and NSCLC patients supports the use of efti in combination with pembrolizumab as a promising new therapeutic option for patients."

Stage 1 Part A (1st line NSCLC, N=17):

• iORR of 53%, with 9 out of 17 patients reporting a Partial Response (iPR) according to iRECIST.
• 71% (12/17) of patients with target lesion decrease (tumour shrinkage responses in all PD-L1 subgroups. 4 out of 9 patients with PRs had a Tumour Proportion Score less than 50% (typically less responsive to anti-PD-1 monotherapy such as pembrolizumab)
• 41% (7/17) of patients were still under treatment at data cut-off, indicating an estimated median PFS more than 9 months
• All three PD-L1 subgroups present, indicating the trial is a PD-L1 all comer study

Stage 1 Part C (2nd line HNSCC):

• iORR has increased to 38.9% (7 out of 18 patients), previously 33% from earlier data cut-off of 20 March
• 1 patient has reported a Complete Response (iCR) and 6 patients reported iPRs, including, 1 iPR after pseudoprogression
• 44% (8) of patients still under therapy
• All three PD-L1 subgroups present -> PD-L1 all comer study

Safety
The combination treatment continues to be safe and well tolerated with no new safety signals reported thus far.

TACTI-002 Recruitment Update
Trial recruitment continues to progress well, with 77 patients out of up to 109 already enrolled at 12 clinical sites across Australia, Europe, the UK and US. Recruitment details for each Part are below and are current as at 29 May 2020.

Further information can be found on the Company's website www.immutep.com or by contacting:

Australian Investors/Media:
Catherine Strong, Citadel-MAGNUS
+61 (0)406 759 268; cstrong@citadelmagnus.com

U.S. Media:
Garth Russell, LifeSci Advisors
+1 (646) 876-3613; garth@lifesciadvisors.com

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1} KEYNOTE-040