Wired.com is running an article on a theory of cancer development which proposes that most tumor growth is driven by a subset of specialized tumor cells called cancer stem cells and that the key to treating cancer in general is to treat these cells in particular. The theory states that cancer stem cells are responsible for stimulating and directing tumor growth just as traditional stem cells are responsible for stimulating and directing organ and tissue growth. Cancer stem cells would help explain why some cancers return after what appears to be a successful treatment and why others do not: if the treatment removes most of the cancerous cells, but the ones remaining are cancer stem cells, then the tumor is likely to return, but if the ones remaining are not stem cells, then the cancer will die off.

The theory is still controversial within certain aspects of the cancer research community, but it is quickly winning over many former skeptics. As an example of just how important many researchers think these treatments will be, GlaxoSmithKline has signed a $1.4 billion deal with Oncomed, the first company who will be conducting human trials on cancer stem cell treatments, for the right to commercialize and market the treatments should the trials prove effective. Oncomed’s leading drug candidate, currently known as M2118, is an example of monoclonal antibody therapy and was developed to bind with cancer stem cells and to disrupt the signaling systems they use to stimulate tumor growth. Monoclonal antibodies are antibodies that are created to bind with the receptors of a particular cell or other antigen, to either stimulate an immune system response which subsequently attacks the antigen or to prevent specific signaling structures from becoming engaged. M2118 has been successful in a number of pre-clinical and animal studies, but has not yet been tested on humans. Wired is reporting that M2118 can be combined with other treatments, so its use as part of a combination therapy can hopefully augment the effectiveness of both treatments.

Oncomed expects to be begin human trials of M2118 later this year, so by early 2009 researchers should have at least a partial data set by which to examine the efficacy of M2118 in particular and of cancer stem cells in general. Studies using mouse models have shown that these cancer stem cells are active in mice and can be treated therapeutically as well, but even Oncomed CEO Paul Hastings knows that success in these murine models is no guarantee of success in human trials. All in all though, Wired quotes Hastings as saying that the company was looking forward to beginning these human trials.

Cancer stem cells represent the latest attempt to solve the problems of cancer once and for all. As cancer is a family of diseases and not a single disease, it is difficult to imagine that a single therapy will be effective across the entire spectrum of cancer disorders; however, cancer stem cells have generated a significant amount of interest in a relatively short period of time and they do represent a fundamentally new class of treatment. Just how effective these treatments are will not be known for months, and probably years to come, but the fight against cancer is being conducted on a number of promising fronts these days and there is real hope among doctors and patients alike that improving treatments are finally changing the dynamics involved in cancer therapy.

Labels: cancer