American Pharmaceutical Partners Inc. received Food and Drug Administration approval late Friday for Abraxane, a key proprietary cancer drug on which the company has been pinning much of its future growth.

The company, based in Schaumburg, Ill. but controlled by Los Angeles Dr. Patrick Soon-Shiong through his privately held American BioScience Inc., saw its share rise $4.78, or 14.1 percent, to $38.71 on late trading in anticipation of the announcement, which came after markets closed.

The approval was for the treatment of metastatic breast cancer after the failure of other first line drugs. The company has touted the drug a form of paclitaxel, a common breast cancer drug as a significant advance in therapy. It does not include toxic solvents that other paclitaxel formulations contain, allowing more of it to be delivered to the patient. It is instead delivered through its binding with protein particles.

The FDA action marks a major milestone for Soon-Shiong, who has been a controversial figure on Wall Street because of the unusual structure of the public company and various legal entanglements he has had in the past.