- 01Efti focus: HNSCC CPS<1 & STS neo.
- 02Root-cause: scale diff 200L vs 2000L in TACTI-004.
- 03FDA Fast Track HNSCC; Orphan Drug STS; Dr Reddy's supports.
Immutep (ASX: IMM) has outlined a more focused development strategy for eftilagimod alfa (efti), concentrating future registration-directed work on head and neck squamous cell carcinoma (HNSCC) and soft tissue sarcoma (STS).
The biotechnology company plans to target HNSCC patients with negative programmed death-ligand 1 expression, defined by a Combined Positive Score (CPS) below one, alongside the neoadjuvant treatment setting for STS.
The decision follows an ongoing root cause analysis of the discontinued TACTI-004 study that has identified subtle structural differences between efti manufactured at different production scales.
Preparations for the next clinical studies have begun, with Immutep targeting a start during the second half of calendar 2027 subject to trial design, regulatory interactions, manufacturing timelines, partnering and available resources.
Manufacturing Differences
Immutep’s investigation identified differences between efti manufactured at 200 litres scale for earlier clinical studies and product manufactured at 2,000L scale for TACTI-004, including a subtle difference in N-glycan structure.
The company considers those differences potentially relevant because TACTI-004 produced a markedly different immune activation profile from previous trials alongside an unexpected clinical outcome, although the root cause analysis remains incomplete.
Based on data available so far, Immutep does not believe the result can be explained by clinical factors such as protocol design, treatment-arm imbalances, or safety findings, or by trial execution factors including randomisation or general clinical conduct.
“We intend to apply these learnings rigorously and focus future potential development on settings where the clinical evidence, biological rationale, time-to-market, and unmet medical need are most compelling,” chief executive officer Marc Voigt said.
Immutep has consequently contracted a new 200L manufacturing run, the scale previously used for 10 good manufacturing practice batches deployed across successful Phase I and Phase II studies including TACTI-mel, TACTI-002, and INSIGHT-003.
Clinical Focus Narrows
For HNSCC, Immutep intends to focus on patients with CPS below one, drawing on clinical efficacy and mature overall survival data in a population it considers to have high unmet need and limited approved treatment options.
Efti has received Fast Track designation from the US Food and Drug Administration for first-line HNSCC, while Immutep described previous FDA feedback on the proposed pathway as constructive.
The STS strategy is centred on the neoadjuvant setting following positive Phase II data that achieved the primary endpoint, with the FDA having granted efti Orphan Drug Designation for STS in April 2026.
Licensing partner Dr. Reddy’s Laboratories has been consulted and supports the proposed approach, while Immutep has also begun preliminary discussions with other parties around the development pathway.
Beyond efti, Immutep continues development of IMP761—its agonist anti-LAG-3 antibody for autoimmune disease—in line with previously disclosed plans as it narrows the near-term clinical strategy around efti.
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