Inhibrx's combination cancer drug shrinks tumors in mid-stage head and neck cancer study

INBRX-106 is an immunotherapy designed to activate OX40, a protein on T cells that helps boost the body's immune response.

Other drugs targeting the OX40 pathway, including Amgen and Kyowa Kirin's rocatinlimab and Sanofi's amlitelimab, have been discontinued.

The company also plans to explore the potential of INBRX-106 in combination with therapeutic cancer vaccines.

"I think what matters to investors here is that this company went after this really difficult biological target, OX40, and were able to produce not just efficacious, but competitive results," said Stifel analyst Dara Azar, adding "we feel good based on...reviewing the data and seeing the numeric proof."

Inhibrx estimates about 30,000 HPV-positive head and neck cancer patients in the U.S. by 2029, of which about 6,000 are first-line recurrent patients representing a $1 billion annual sales opportunity.

Shares of the company, however, were down 8.8% at $110.45.

"We can't provide any explanation for the stock movement today, but it's a great entry point for anyone looking at the stock. Today's data was very de-risking for the program," said CEO Mark Lappe. The HPV-positive results don't limit where we can go but just the opposite, he added.

Inhibrx Biosciences said on Tuesday its experimental combination cancer drug helped reduce tumors in a mid-stage study in patients with a type of head and neck cancer.

In a 68-patient trial for head and neck squamous cell carcinoma that has spread and is inoperable, the drug INBRX-106 combined with Keytruda shrank or eliminated tumors in 48.3% of patients, versus 26.5% for Keytruda alone.