A clinical study of Celgene Corporation’s investigational cancer drug, Revlimid (lenalidomide), has been temporarily halted on safety concerns over a higher incidence of blood clots in patients, according to the Wall Street Journal.

Trial organizers were reportedly concerned that some patients were not regularly taking aspirin, as recommended, and so the evaluation was suspended to allow the rules to be modified to command the simultaneous use of this blood thinner.

The National Cancer Institute-funded, 250-patient trial is assessing the efficacy of Revlimid when administered in combination with a steroid for the treatment multiple myeloma. Although lead study investigator SV Rajkumar, an oncologist at the USA’s Mayo Clinic, would not divulge how many participants developed blood clots, he did note that the trial was expected to resume shortly, the WSJ reports.

Suspension of the investigation comes at a tender time for the company, which is expecting a decision on its New Drug Application for the agent as a therapy for transfusion-dependent anemia in patients with the rare blood disorder myelodysplastic syndrome, who are consequently at greater risk from developing acute leukemia.

According to industry observers, the agent, which holds Orphan Drug status in the USA and Europe, is one of the most eagerly-anticipated new cancer drugs on the verge of approval, and analysts have forecast peak annual sales of $500 million-$1.0 billion [[15/09/05c]].