Australian biotech Immutep has terminated a late-stage study evaluating its lead oncology candidate, eftilagimod alfa (efti), in combination with MSD’s Keytruda (pembrolizumab) in non-small cell lung cancer (NSCLC).
This follows a recommendation from an independent data monitoring committee (IDMC), which warned Immutep that efti, a lymphocyte activation gene-3 (LAG-3) protein-targeting immunotherapy, plus Keytruda, was unlikely to meet the trial’s primary endpoints of overall survival (OS) and progression-free survival (PFS).
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Following this outcome, Immutep will wind down operations for the Phase III TACTI-004 study (NCT06726265). This means the biotech will stop enrolling new patients and end the study once it has completed the appropriate patient follow-ups.
Otherwise known as KEYNOTE-F91, the TACTI-004 trial was evaluating the potential of eftilagimod alfa plus Keytruda in the frontline NSCLC setting, with patients randomised to receive either efti plus standard of care (SoC) Keytruda-platinum doublet chemotherapy or a placebo and SoC combination.
In a 13 March statement, Immutep’s CEO, Marc Voigt, voiced his “surprise” with the outcome of the IDMC’s futility analysis – pointing to the drug’s performance in previous studies. In the Phase II TACTI-003 trial (NCT04811027) in head and neck cancer, efti and Keytruda triggered an overall response rate (ORR) of 34% regardless of programmed cell death ligand 1 (PD-L1) expression.
However, the drug missed its primary PFS endpoint, while failing to significantly improve OS in the Phase IIb AIPAC study (NCT02614833) in HR-positive, HER2-negative metastatic breast cancer.
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By GlobalDataNow, Voigt says Immutep will conduct a “comprehensive review of the available data” to understand the results and determine what comes next for the immunotherapy’s programme, which currently spans across soft tissue sarcomas and non-squamous NSCLC, as well as breast cancer and head & neck cancer.
It appears that this readout has not deterred Immutep from progressing efti, as the company noted it remains “focused on advancing its pipeline… including efti”.
However, investors did not respond well to the readout, as Immutep’s stock value dropped more than 80% from $2.76 at market close on 12 March to $0.55 when the markets opened today [13 March].
Analysts unsure on efti’s future
While Immutep is standing by efti’s potential by continuing the drug’s development, some have raised concerns about the drug’s efficacy. This includes analysts from investment bank Jefferies, who noted that efti’s efficacy is now “obviously in question” following the discontinuation of TACTI-004.
According to Biswajit Podder, oncology and haematology analyst at GlobalData, the trial’s discontinuation in NSCLC marks a “meaningful setback” for Immutep.
“The study was stopped after a planned interim futility analysis by the IDMC based on the available efficacy and safety data, so this looks like a failure to show enough clinical benefit rather than a new safety issue,” Podder said.
This matter as frontline metastatic NSCLC already has strong approved immunotherapy backbones, Podder added, meaning the bar for adding a new agent is “very high”.
However, Podder does not believe that TACTI-004’s discontinuation invalidates efti’s mechanism in solid tumours overall. “The more credible opportunity for efti now looks selective rather than broad; head and neck cancer still looks promising,” he commented.
