Stryker Corp’s bone-growth putty for spinal surgery should not be approved for expanded use in a wider population, advisors to federal drug regulators said on Tuesday. A Food and Drug Administration advisory panel of outside experts voted 6-1 to recommend against wider approval of the genetically engineered protein, already cleared for limited use in certain spine surgeries to treat back pain. Concerns among the panel included bias that may have crept into the company’s clinical trial and lack of scientific rigor in establishing safety and effectiveness.
Stryker’s first three analyses of its main study showed the putty failed to perform as well as the comparison treatment.
“I have major concerns about the biases in this study,” including reliance on patients’ self-reported satisfaction while at the same time knowing which group they were put in, said panel member Kathleen Propert, a statistician at the University of Pennsylvania.
After initial enthusiasm about the product, dubbed OP-1, weak trial results led to diminished expectations for its approval among Wall Street analysts. FDA staff had pointed to major shortcomings in the data, leading shares to fall about 1.7 percent on Friday.
“The expectations were pretty dour going in,” said Raj Denhoy, analyst with Thomas Weisel Partners.
The company said in a statement that it was disappointed with the vote and that it was reviewing its strategic options for the drug. Several panel members said a new study would likely be required to win approval. Stryker’s main study sought to prove “non-inferiority”, and compared the putty to a procedure in which surgeons take a piece of bone from a patient’s hip and use it to fuse the vertebrae. Earlier, the panel said the main study of about 300 people, did not prove the drug was effective, and it noted safety concerns including a potential for negative immune responses. The FDA usually follows recommendations from its advisory panels but is not required to do so.
Last year, the FDA said certain bone growth products, including OP-1, had been linked to life-threatening complications when used without approval. No definitive link was found though between the products and the adverse events, which included neck swelling and breathing problems.