Two pharmaceutical companies have placed bets valued at up to $100 million on different start-up biotech companies that are racing to develop gene therapies based on the p53 tumor suppressor gene.

The strategic alliances linking Rhone-Poulenc Rorer to Introgen Therapeutics Inc. and Schering-Plough to Canji Inc. underscore the potential market size of p53-based gene therapies. In both cases the pharmaceutical companies will provide up to $50 million for marketing rights.

But the presumed importance of p53 has also made it a popular research target, leaving open intellectual property issues that probably won't be resolved for years.

The scale of the potential market and the number of potential indications - the gene is thought to be involved in about half of all cancer tumors - and the difficulty of delivering it mean that the basic patent on the use of p53 in gene therapy, if it is issued, may not be the key to commercial viability.


RPR and Schering are betting on their collaborations' abilities to obtain and defend patents, to develop effective cancer therapies, to get them into the clinic and through the regulatory process. Although both sets of companies claim to have solid patent positions, it is possible that either could build significant businesses without proprietary rights to p53 gene therapy.