Immutep Limited provided an update on the ongoing development of its product candidates, eftilagimod alpha (“efti”) and IMP761 for the quarter ended 31 December 2021. Efti Development Program for Cancer: AIPAC - Phase IIb clinical trial - final data: The company reported final Overall Survival (OS) data from its Phase IIb AIPAC clinical trial evaluating efti in metastatic breast cancer (MBC) in November 2021, as a late breaker poster at the Society for Immunotherapy of Cancer (SITC) Annual Meeting. The late-stage trial showed very encouraging OS data, including a statistically significant and clinically meaningful benefit in three patient predefined subgroups representing a majority of patients.

A survival benefit of +7.5 months was observed in patients < 65 years, reflecting a > 50% improvement compared to the control group. A +19.6 month survival benefit was seen in patients with low monocytes, a benefit of > 150% compared to the control group. Lastly, a survival benefit of +4.2 months was reported in luminal B patients, reflecting a > 33% benefit compared to the control group.

The data from these subgroups was improved data versus the interim data presented by the company in December 2020. In addition, a statistically significant Quality of Life preservation was demonstrated in the first 6 months from patients in the efti group in the total population. A statistically significant increase in peripheral CD8 T cells in patients in the efti group of the total population was also observed and positively correlated with improved OS.

These final results have given the company additional confidence efti can deliver a meaningful clinical improvement for diverse sets of cancer patients, as the Company started its preparations for a larger clinical trial in MBC via its Phase III clinical trial, AIPAC-003. AIPAC-003 - planned Phase III trial: In October 2021, the company received positive feedback from the European Medicines Agency (EMA) regarding its clinical development program for efti. The company has also been interacting with the US FDA and is providing additional information relating to efti's unique mechanism of action as an agonist that leads to T cell expansion and proliferation (rather than all other LAG-3 products in development which are antagonists that block an immune checkpoint).

Interactions with the EMA, US FDA and other regulators are ongoing. The feedback from competent authorities, along with insights from a rigorous engagement process with Key Opinion Leaders and other stakeholders will help the company generate a final study design. TACTI-003 - Phase IIb clinical trial: During the quarter, the company continued recruitment of patients for the TACTI-003 clinical trial.

At present, 6 of approximately 154 patients with 1st line HNSCC have been enrolled into the trial at active clinical sites. The study is in its start-up phase and additional sites are planned to be initiated in the first quarter of 2022. The company also presented the trial design for TACTI-003 via a poster at the SITC 2021 conference in November 2021.

It is a Phase IIb multicentre, open label, randomised and controlled trial. Fast track designation for 1 st line HNSCC by the US FDA was granted in April 2021. TACTI-002 (also designated KEYNOTE-PN798) - Phase II clinical trial: The company also reported data from the 2nd line HNSCC patients (Part C) of TACTI-002 at the SITC 2021 conference.

Part C is showing encouraging antitumor activity. An encouraging Overall Response Rate (ORR) was reported, with 29.7% of patients responding to the combination therapy of efti and pembrolizumab. In addition, a favourable duration and depth of responses was observed, with 5 Complete Responses and a minimum duration of response extended to > 9 months across all responding patients.

The responses continue to be reported in PD-L1 low and high expressors. During the quarter, the company enrolled and dosed the last patient in the expansion stage of Part A (1st line non-small cell lung cancer (NSCLC)), completing the recruitment of all cohorts of the TACTI-002 study. A total of 189 patients are now participating in TACTI-002 across Parts A, B, and C at approximately 20 clinical sites in Australia, Europe, and the US.

Additional data from TACTI-002, particularly in NSCLC, are planned to be reported in the first half of calendar year 2022. Data from the 114 patients in Part A (1 st line NSCLC) is expected to inform potential late-stage development of efti in this important indication.