Switzerland’s Roche has suffered a dent to its stock after revealing that it has temporarily suspended recruitment into a Phase II dose-finding study with its new anaemia drug Mircera.

The company noted that it has acted on the recommendations of an independent drug safety monitoring board looking at a study of Mircera/Cera (continuous erythropoietin receptor activator). in anaemic patients with advanced non-small-cell lung cancer receiving chemotherapy. The decision to stop enrolment has been taken “because of a numerical imbalance in the number of deaths across the four arms of the study” (three arms with Mircera and one with darbepoetin alfa, Amgen’s Aranesp).

Roche noted that the investigators reported all deaths to be unrelated to the study drugs and there appears to be no association of these events to excessive haemoglobin levels or the administered doses based on the current review of the data. The firm added that it has not observed a similar type of imbalance in previously-completed studies with Mircera in cancer patients receiving chemotherapy and no deaths have been reported in another ongoing study in Japan.

Nevertheless, some analysts are saying that the suspension of enrolment reflects growing safety concerns over the class of erythropoietin-based drugs such as Amgen Aranesp and Johnson & Johnson's Procrit (epoetin alfa). Jim Reddoch, an analyst with Friedman, Billings, Ramsey, said in a research note that “we believe this event adds an additional black cloud to EPO drugs in cancer patients and may ultimately force physicians to become more cautious in their EPO use and payors to cut back on reimbursement."

It is feared that the suspension is unlikely to help Roche's bid to win US approval for Mircera and the US Food and Drug Administration extended its review period for the drug in chronic kidney disease in December. A decision is expected on or around May 21.