Exelexis suspends XL999 P2 trials

EXEL suspended enrollment of patients in the Phase II cancer program for XL999 after a preliminary review showed four out of 14 patients enrolled during October experienced serious adverse cardiovascular events. EXEL said 12 out of 117 patients had experienced serious cardiovascular events through the end of September. Because all but one of the events occurred on first administration, EXEL is continuing to treat the patients already enrolled in the trial. To date, 115 of the 131 patients enrolled have received repeated doses with no cardiac toxicities. Dosing has been every week or every other week, ranging from two doses (two weeks) to 53 doses (about two years). EXEL expects enrollment to be suspended for two weeks to three months while it reviews data. XL999 is a spectrum selective inhibitor of VEGF, FGF and platelet derived growth factor (PDGF) receptors and FMS-like tyrosine kinase 3 (FLT3). On Thursday, EXEL fell $1.13 (12%) to $8.21.