Merck Suspends Enrollment in Drug Trial

Patients now in the trial will continue to be dosed and will receive additional monitoring, a Vertex spokesman said. The spokesman did not know how many patients were already enrolled in the trial.

Vertex and Merck plan a full analysis of all efficacy and safety data for the treatment, MK-0457, which the is lead investigational Aurora kinase inhibitor in their collaboration.

The midstage trial began in January and was designed to enroll up to 272 patients.

MK-0457 was found to cause QTc prolongation in one patient, according to preliminary data. The QT interval is a measurement which relates to the heart rate.

The companies expect to start an early-stage trial of Aurora kinase inhibitor, VX-689, in patients with advanced and/or refractory solid tumors in early 2008.

The companies discontinued development of another Aurora kinase inhibitor MK-6592 (VX-667) after the compound did not meet pharmacokinetic objectives in a Phase 1 clinical study, Vertex said Tuesday.

In after-hours trading, Vertex shares lost 82 cents, or 3.3 percent, to $23.75. They earlier lost 51 cents, or 2 percent, to $24.57 in the regular session. Merck shares were unchanged at $57.92.