Exelixis submits IND for XL281 RAF inhibitor

Exelixis, Inc. has submitted an investigational new drug (IND) application to the U.S. Food and Drug Administration for XL281, a novel anticancer compound designed to potently inhibit the RAS/RAF/MEK/ERK signaling pathway. Mutational activation of RAS occurs in about 30 percent of all human tumors, including non-small cell lung, pancreatic, and colon cancer. XL281 is a specific inhibitor of RAF kinases, including the mutant form of B-RAF, which is activated in 60 percent of melanomas, 24-44 percent of thyroid cancers, and 9 percent of colon cancers.

"XL281 emerged from our strategy to advance novel compounds that potently and selectively inhibit mutationally activated downstream kinases implicated in promoting the growth of specific tumor types," said George A. Scangos, Ph.D., president and chief executive officer of Exelixis. "We have identified five additional next-generation compounds that selectively inhibit key targets in the PI3 kinase, RAS/RAF and JAK/STAT pathways and expect to file IND applications throughout the next nine months."

SO, what's RAF? What's a kinase? First of all there are specific paths from which the cell uses to obtain certain goals. For example, when a cell gets a growth factor binding to the cell surface, it activates proteins downstream all the way to the nucleus. RAF is one such protein in the cascade from the EGFR growth pathway. Stopping it's function thus, my limit how the cell grows, an important step in cancer drugs.

Kinases are enzymes that use ATP as energy to transfer a phospate group and attach it to another protein, at specific amino acids, being tyrosine, serine and threonine.

Exelixis trades on the Nasdaq: EXEL and was trading up 16 cents on friday to 9.82. I would keep an eye on this stock, I think it should spike up with it's encouraging pipeline of next generation protein inhibitors.