This agent proved difficult to synthesize and could only be obtained from the bark of the Pacific Yew tree, which forced the NCI into the costly business of harvesting substantial quantities of yew trees from public lands. After 4 years of clinical testing in solid tumours, it was found in 1987 (23 years after its initial discovery) to be effective in ovarian cancer therapy. Notably, this agent, although developed by the NCI in partnership with Bristol-Myers Squibb, was exclusively marketed by BMS (who had utilized the synthetic methodology developed by Robert Holton at Florida State University) who went on to make over a billion dollars profit from Taxol.[citation needed]