Immutep Quarterly Activities Report Q4 FY23 - Seite 2

Based on the robust initial results, the trial’s Data Monitoring Committee recommended extending OS follow-up data collection to show mature 3-year and potentially 5-year rates. More mature OS data and additional efficacy and safety results will be presented at a major medical conference in H2 CY2023.

• 2nd Line Head and Neck Squamous Cell Carcinoma (2L HNSCC)

Immutep reported positive final TACTI-002 data in 2L HNSCC patients in a poster presentation at the ASCO 2023 Annual Meeting in June. Deep and durable responses were seen from efti plus pembrolizumab regardless of patients’ PD-L1 expression levels (measured by Combined Positive Score or CPS). Encouragingly, median Duration of Response had not been reached (meaning the response is still ongoing) despite a long median follow up of 39 months, providing continued evidence of the durable responses efti helps drive. Notably, one long-lasting Complete Response occurred in a patient with negative PD-L1 expression, who wouldn’t typically be expected to respond to PD-L1 monotherapy.

Efti plus pembrolizumab led to an encouraging overall response rate (ORR) of 29.7% and Complete Response (CR) rate of 13.5% in 2L HNSCC patients. Responses were seen across all PD-L1 subgroups. A promising ORR of 38.5% & 60%, median Overall Survival (mOS) of 12.6 & 15.5 months, and 12-month Overall Survival (OS) rate of 52.0% & 66.7%, were seen in patients with a PD-L1 CPS of ≥1 and a PD-L1 CPS ≥20, respectively. The results from the chemo-free IO-IO combination of efti plus pembrolizumab in 2L HNSCC patients with a PD-L1 CPS ≥1 compare favourably to reported results from a registrational trial of anti-PD-1 monotherapy in the same patient population, which showed a 17.3% ORR, mOS of 8.7 months, 12-month OS rate of 40%, a CR rate of 2%, and mDoR of 18.4 months.¹

TACTI-003 – Phase IIb clinical trial in 1st line HNSCC
Immutep’s ongoing TACTI-003 trial is evaluating efti in combination with pembrolizumab in the 1st line setting in HNSCC. The trial has reached ~91% patient recruitment, and Immutep is on track to report top-line results from TACTI-003 in H2 of CY2023.

TACTI-004 Phase III registrational trial in 1st line NSCLC
In May, Immutep received positive feedback from the US Food and Drug Administration (FDA), which is supportive of a registrational trial to evaluate efti in combination with an anti-PD-1 for the treatment of 1L NSCLC. Among the items discussed at the meeting were the toxicological package and general aspects of the trial design, including statistics and potential patient population with a focus on 1st line NSCLC patients with a Tumor Proportion Score (TPS) PD-L1 of >1% for which efti plus pembrolizumab has already received Fast Track designation. The Company is advancing its preparations for the trial.