Two drugs from unlikely sources -- an ocean-growing sponge and a European evergreen tree -- apparently team up well to prevent the spread of cancer cells.The sponge-based drug, discodermolide, works with a yew tree derivative called paclitaxel to thwart tumor cell growth, according to research published in the July 15 issue of Cancer Research.In fact, using the drugs in combination is several times more effective than using either drug alone, concluded researchers at the University of California, Santa Barbara.Both drugs prevent cancer spread by interfering with tumor cells’ ability to divide, keeping cells stalled in a pre-division stage of growth.Paclitaxel currently is an approved drug for the control of cancer growth, while discodermolide is undergoing phase one clinical trials.