The patient in question developed a QTc prolongation, which can increase the risk of sudden cardiac death. Although the two pharma firms will continue to treat chronic myelogenous leukaemia (CML) patients already in the Phase II trial for MK-0457 (VX-680), no new patients will be recruited. A Phase I trial of the drug has also been suspended. The news is particularly worrying for Merck and Vertex as MK-0457 is not the only aurora kinase they are developing together. Another of the drugs has recently been discontinued "after the compound [MK-6592/VX-667] did not meet pharmacokinetic objectives in a Phase I clinical study". Despite these setbacks, the pharma giant did say that it still plans to begin clinical development of VX-689 early next year. Whether the problem is definitely caused by MK-0457 is, as yet unclear, but if the two are linked then the news could spell trouble for the numerous other companies with aurora kinase inhibitors in various stages of clinical development. MK-0457 is the most advanced drug with this target in clinical development. Miikana Therapeutics and SuperGen both had aurora kinase inhibitors in preclinical development - MCK-1693 and MP529 respectively - while many other companies also had drugs of this class in Phase I trials. These include Astex Therapeutics (AT9283, actually Phase I/II), AstraZeneca (AZD1152), Cyclcel Pharmaceuticals (CYC116), Millennium Pharmaceuticals (MLN8054 and MLN8237), Sunesis Pharmaceuticals (SNS-314) and finally Merck KGaA, in collaboration with Rigel were testing R763 (AS703569) in a Phase I trial as well.