Development of gene therapies using the p53 tumor suppressor gene has been a two-horse race, between Schering-Plough Corp. and its Canji Inc. subsidiary on the one hand, and Rhone-Poulenc Rorer and partner Introgen Therapeutics Inc. on the other. The pharma companies are betting about $50 million each on the outcome (see BioCentury Oct. 31, 1994).

The intellectual property issues surrounding p53-based gene therapies became one step more complicated last week, with the issuance of the first U.S. patent on the p53 tumor suppressor gene. Patent No. 5,532,220 issued to the University of California. Schering