A trial of Celgene's cancer drug Revlimid was temporarily suspended as of April 4, according to the Southwest Oncology Group, or SWOG, which was running the late-stage trial.
The statement, made on the group's Web site, did not give details.
However, Matthew Osborne, an analyst at Lazard Capital Markets, said he believes the suspension is designed to alter the protocol to allow patients to switch to a different treatment regimen, which was recently shown to improve survival.
Brian Gill, a spokesman for Celgene, confirmed that the trial has been temporarily closed but said the company could shed no light on the reason for the suspension.
"Matt Osborne's assumptions are very interesting and could well have validity but we don't have any definitive information," he said.
The SWOG study is testing Revlimid plus standard dose dexamethasone, a steroid, versus dexamethasone alone as a first-line treatment for multiple myeloma.
The news comes on the heels of a recent finding by the Eastern Cooperative Oncology Group, or ECOG, that patients who took Revlimid plus low-dose dexamethasone had a survival advantage over patients who took Revlimid plus standard dose dexamethasone.
It is not clear whether SWOG plans to stop the trial completely, but Osborne said that with a survival advantage for Revlimid plus low-dose dexamethasone it could be considered unethical to continue patients on standard dose dexamethasone alone.
"What this does is build on the evidence that Revlimid plus low-dose dexamethasone will become the standard of care in frontline multiple myeloma," Osborne said.
Currently, Revlimid is approved by the U.S. Food and Drug Administration in combination with standard-dose dexamethasone for patients with multiple myeloma who have received at least one prior therapy.
Osborne said, however, that as data from the Revlimid plus dexamethasone trials is further disseminated, physicians are likely to increase their use of Revlimid plus low-dose dexamethasone as their first choice therapy, even though it has not formally been approved for such use.
Physicians are allowed to prescribe drugs "off label" but companies are not allowed to market them for unapproved uses.
Revlimid is a successor to Celgene's drug Thalomid, currently the leading treatment for multiple myeloma.