Transgenic mice whose chromosomes carry extra copies of thepim-1 oncogene are 25 times more sensitive to cancer-causingagents than are normal mice, an article in today's CancerResearch reports.

This finding offers the prospect of a lower-cost animal model totest chemicals for their likelihood to cause cancer. Carcinogenictesting is a major portion of the broader $1 billion annualmarket for toxicology testing of new products.

It could also be a boon to GenPharm International of MountainView, Calif., the exclusive licensee of the so-called PIM mouse.GenPharm plans to ship the PIM mouse to several unnamedcompanies this spring, said Howard Rosen, GenPharm'smanager of business development.

"The results of this research demonstrate for the first time thata transgene can make an animal more responsive totumorigenic agents," said Dr. Anton Berns, the study's director.Berns, of the University of Amsterdam, is also a scientificadviser to GenPharm.

The study showed that exposing PIM mice to the carcinogenethylnitrosourea, even in low amounts, induced tumorlymphomas.

GenPharm maintains that the PIM mouse is much less likelythan other oncogene-containing transgenic mice to developspontaneous tumors, which can skew results of tests ofchemicals under study. The Oncomouse, developed by Du Pontunder license from Harvard University, has high spontaneousrates of tumor formation, Rosen said.

GenPharm hopes that the PIM mouse might replace traditionalresearch rodents in bioassays at an 80 percent cost savings tolaboratories, said Rosen. Traditional tests of a substance'sability to cause cancer can require more than 1,000 animals,take two years to complete and cost more $1 million. Incontrast, the PIM mouse assay requires only six months toform a lymphoma and uses fewer than 200 animals, resultingin more efficient drug development.

Stratagene Cloning Systems of La Jolla, Calif., is developing atransgenic mouse to detect carcinogen mutation rates. Dr. JayShort, its vice president of biological operations, predicted thatcompanies may want to use both mice because each hasadvantages. The Stratagene assay takes only three days, hesaid.

The PIM mouse shows directly if a chemical causes tumorgrowth, said Rosen.

Rosen sees the PIM mouse as an "important near-termopportunity" for GenPharm. Longer-term, it is also developingtransgenic animals for disease models and protein productionfactories.

-- Carol Talkington Verser, Ph.D. Special to BioWorld

(c) 1997 American Health Consultants. All rights reserved.

No Comments