Bristol-Myers shares fall 10% after cancer treatment disappoints

A researcher in a Bristol-Myers Squibb laboratory.
Emile Wamsteker | Bloomberg | Getty Images
A researcher in a Bristol-Myers Squibb laboratory.

Shares of Bristol-Myers Squibb fell 10 percent Monday, after details from a clinical trial showed the pharmaceutical company's Opdivo cancer immunotherapy drug performed worse than investors had expected.

At a European medical conference on Sunday, New York City-based Bristol-Myers released the results of the closely watched trial. They showed that patients did worse on Opdivo than those on chemotherapy, and survived only 4.2 months before their disease worsened.

That compares with 5.9 months for patients on chemotherapy, though the difference had no statistical significance, Reuters reported.

Five-day performance of Bristol-Myers Squibb

Investors had been closely eyeing Opdivo's results in wake of the drug's failed trial in August, which resulted in the loss of $22 billion from Bristol-Myer's market value in one day.

Yet some wondered whether Opdivo failed simply because it was tested in patients for whom it was unsuitable. As a result, some analysts had expected the drug to at least work for lung cancer patients who had high levels of the protein PD-L1, according to Reuters. But there was no evidence of that in the latest results.