GSK buys into Cancer Stem Cell Vision

London, UK, Philadelphia, PA and Redwood City, CA -

It was recently announced that the California venture capital backed company OncoMed has struck a deal with GlaxoSmithKline that could be worth up to 1.5 Billion in milestone payments alone, not counting royalties. Arguably this is one of the highest valued deals for a technology that is still preclinical.

In order to give a background to this, we should first review the cancer stem cell theory. OncoMed scientists believe that tumors are maintained by a small fraction of cells that reside in the tumor. In other words about 99% of cells making up the tumor mass are not capable of seeding and making new tumors, it is about 1% or less than 1% of the cells that make a tumor mass that are actually "cancer stem cells". This idea sounds basic but its implications are profound. For example, ALL drug development is usually performed using cell lines in vitro and measuring reduction of tumor size in animals in vivo, however no one has really used "tumor stem cells" as targets for drug development. Well this is not exactly true.

The scientific founder of OncoMed, Dr Michael Clarke from the University of Michigan School of Medicine has been filing and obtaining patents on ways of isolating tumor stem cells for numerous years. For example, patent 7,115,360 specifically covers screening of cancer stem cells with inhibitors. The phenotype of the cancer stem cell is described in detail in this patent. Patent 6,984,522 covers the composition of matter for tumor stem cells, which basically blocks others from using the cells for drug development.

OncoMed has actually developed a portfolio of antibodies to novel antigens on the tumor stem cells, some of these (OMP-21M18) anticipated to enter the clinic in 2008.

An interesting point however is that a patent with a priority data in 1978, 4,411,990 actually teaches the existance of tumor stem cells and how to culture them. Actually Irv Weissman also has a patent in this area teaching that one can select tumor stem cells based on expression of an activated beta catenin pathway. Along these lines it is interesting that if one blocks the hedgehog pathway, one can deplete tumor stem cells in some models.

Several important papers that one should read if one is interested in this area is the colon cancer stem cell paper from John Dick's group, in which they demonstrated that CD133+ cells possess much higher tumor forming ability than CD133- cells, as well as the paper in which BMP4 administration induced tumor stem cells to differentiate, the paper in which it was demonstrated that tumor stem cells selectively express the immune suppressive protein CD55 and the paper in which tumor stem cells were demonstrated to be chemoresistant.

We at StemCellPatents.com believe that the area of tumor stem cells will become more and more prolific in the years to come, after the "old school" gets over the fact that a lot of the previous drug development paradigms have to be discarded...a process that will not be easy.