When cancer researchers talk about a promising area of research called the hedgehog pathway, they aren't studying spiny little mammals.

Rather, the term references a series of reactions inside a cell believed to play a key role in the proliferation of certain cancers. As a result, many companies including Roche Holding AG (RHHBY), Infinity Pharmaceuticals Inc. (INFI) and Bristol-Myers Squibb Co. (BMY) are developing drugs - called hedgehog inhibitors - that block the pathway and aim to limit the spread of cancerous cells

Any such drugs, though, aren't likely to hit the shelves until the first half of the next decade.

The hedgehog pathway got its name when researchers studying body development found it was responsible for creating mutant fly larvae that were furry, like little hedgehogs.

In humans, the pathway is mostly dormant except during embryonic development, when it plays a key role in cell differentiation from determining organ formation to the placement of your fingers. This role designates the drugs in development as off-limits to pregnant women.

Specifically, the hedgehog pathway causes problems when it produces signals that promote tumor survival and growth. This occurs from mutation or by being switched on by tumors to make the environment more conductive for disease growth.

Drug companies are working on compounds stop to this process, by blocking the specific protein that does the signalling in the cell.

Because such drugs would only prevent tumor growth, they would be used in conjunction with commonly used chemotherapies. In some cancers it is believed that using hedgehog inhibitors may allow such cell-killing therapies to have better access to cancer cells and make overall treatment more effective.

Roche's Genentech, working with Curis Inc. (CRIS), is leading the pack with its compound GDC-0449, which is currently in Phase II studies in basal cell carcinoma, colorectal cancer, and ovarian cancer.

Infinity Pharmaceuticals is developing IPI-926 in a Phase I study in solid tumors and expects to move forward with later stage trials in a number of cancers including pancreatic, small-cell lung cancer, and some blood cancers.

Bristol-Myers and Exelixis Inc. (EXEL) are also in Phase I development of BMS-833923 in patients with advanced solid tumors.

All these therapies generally mimic the action of a natural compound called cyclopamine, that was discovered in the 1950s as the cause of a number of sheep being born with one eye, a condition called cyclopia.

Cyclopamine isn't potent enough to be an effective treatment in humans, but it is thought to bind to the signalling protein, thus halting its activity down the pathway.

Because the drugs are in early development, the full extent of potential side effects isn't known. But the targeted nature of the treatments and lack of hedgehog activity in adults has researchers hopeful that adverse effects will be minimal with prolonged use.

David Tuveson, an oncologist at Cancer Research UK studying Infinity's compound in pancreatic cancer with no connection to the company, would be happy to trade side effects for a patient benefit in the especially lethal form of the disease where survival is measured in weeks.

"If we are treating pancreatic cancer for more than a year, that is a problem I can deal with," he said.

-By Thomas Gryta, Dow Jones Newswires; 212-416-2169; thomas.gryta@dowjones.com