Inhibrx Biosciences (INBX) shares are up Monday after the company reported that its experimental drug INBRX-106, when combined with Merck's (MRK) blockbuster immunotherapy Keytruda, shrank tumors far more effectively than Keytruda alone in patients with head and neck cancer.
The interim results come from the Phase 2 portion of the HexAgon study. In the combination arm, 44% of patients had a confirmed objective response, compared to just 21.4% in the control group receiving Keytruda solo. That's more than double the response rate — a meaningful jump for a patient population that often runs out of options.
But it's not just about who responds. The quality of those responses also stood out. Most patients in the combo group saw their target lesions shrink by more than half, and three patients had a complete radiographic response, meaning no detectable cancer remained on scans. Deeper tumor reductions like these often translate into longer-lasting benefits, though we'll need to see the progression-free survival data to know for sure.
Inhibrx expects that data in the fourth quarter of 2026 and plans to kick off a Phase 3 trial in the third quarter. The company is clearly betting big on INBRX-106, which is designed to activate OX40, a protein on immune cells that acts like a booster pedal for the immune system. The idea is that adding an OX40 agonist to a checkpoint inhibitor like Keytruda could turn more cold tumors hot.
Beyond head and neck cancer, Inhibrx is expanding the pipeline. A perioperative non-small cell lung cancer (NSCLC) study is expected to start later this quarter. The company believes OX40 agonism may have the strongest curative potential in earlier-stage disease, when the immune system is still relatively intact. A first-line metastatic NSCLC study is also on the docket for 2027.
And Inhibrx isn't stopping at checkpoint inhibitors. The company plans to test INBRX-106 alongside other therapies that could benefit from T-cell costimulation, including vaccines, T-cell engagers, and CAR-T therapies. That's a broad strategy, but it reflects a growing belief in the field that OX40 agonists could be versatile partners in combination regimens.
As of publication Monday, Inhibrx shares were up 3.95% at $139.66.
