Isolation and use of solid tumor stem cells

Patent Number: 6984522

In the cancer patient it is believed that tumors are actually a heterogeneous population of cells, and that not all the tumor cells have equal proliferative capability. This concept of the "tumor stem cell" maintaining the bulk of the tumor population is very important since many believe that the cells targeted by conventional therapies are not the actual tumor stem cell but derivatives thereof. This means that it is useless to kill the 99% of the cells since the 1% stem cell will just continue to make up for the death of the 99%. This patent describes ways of identifying tumor stem cells in solid tumors of epithelial origin. The patent claims revolves around the phenotype of the tumor stem cell being CD44+, negative for one or more of the following differentiation markers (CD2, CD3, CD10, CD14, CD16, CD31, CD45, CD64, and CD140b) and not expressing, or weakly expressing CD24. The first independent claim covers "An isolated population of solid tumor stem cells ", the second covers "An enriched population of solid tumor stem cells " and the third covers "A method of enriching for a population of solid tumor stem cells". This patent will be useful for generation of approaches that target the tumor stem cell has opposed to progeny thereof. One interesting question is if the tumor stem cells described in this patent are actually similar to the tumor stem cells published by Ralph Reisfeld's group from Scripps (La Jolla CA) which bear a "side population" phenotype ( Kruger JA et al. Characterization of stem cell like cancer cells in immune competent mice. Blood. 2006 Aug 15;).

View this patent on the USPTO website.