LAG-3 Pioneer Immutep Fails Phase 3 Lung Cancer Study, Stock Crashes 88%

By Curie | Biotech Reporter

March 13, 2026 — Australian biotech Immutep's years-long bet on the LAG-3 checkpoint has suffered a major setback. The company announced Friday that its lead drug, eftilagimod alfa (efti), failed a Phase 3 trial in first-line non-small cell lung cancer, triggering an 88% collapse in its share price.

The Phase 3 study, called TACTI-004, was evaluating efti in combination with Merck's Keytruda (pembrolizumab) and chemotherapy. An independent data monitoring committee recommended discontinuing the trial after a planned interim futility analysis concluded the study was unlikely to meet its primary endpoints of progression-free survival and overall survival.

"We are very disappointed and surprised with the outcome of the futility analysis, in light of efti's performance in every other clinical trial," said CEO Marc Voigt in a statement. He thanked patients and investigators and said the company is conducting a "comprehensive review of the available data" to understand what went wrong.

The failure is a significant blow to the broader LAG-3 field. A few years ago, the oncology world wondered if LAG-3 might become the third major checkpoint inhibitor after PD-1 and CTLA-4. Bristol Myers Squibb brought the first LAG-3 drug to market in 2022 with Opdualag (relatlimab + nivolumab), but the class has struggled to expand beyond its initial melanoma approval.

MSD abandoned its own LAG-3 program, favezelimab, in 2024 after failed trials in lung and colorectal cancers. Now Immutep's failure in the largest checkpoint market — first-line NSCLC, which generates billions in Keytruda sales — raises fresh questions about whether the LAG-3 target can deliver on its promise.

Immutep's stock fell from roughly AU$1.20 to under AU$0.15 following the announcement. Despite the setback, the company said it expects its cash runway to extend beyond the previously guided Q2 2027, thanks to cost savings from terminating the trial. The company still has efti in trials for head and neck cancer, breast cancer, and soft tissue sarcoma.