People following (if only occasionally) this blog do probably agree with the importance of the evolutionary dimension of cancer to study its progression. Although somatic evolution is something that multicellular organisms can use to their advantage, witness the immune system, it is also something to be shielded from: cancer, viruses, bacteria.

It is good to read that more and more research groups are considering therapies that take evolution into account. This can range from those therapies that are aware that tumours will evolve towards resistance (to the therapy) to therapies that use evolving populations.

Bacteria image from wikipedia:

One way to do this would be to use anaerobic bacteria. Not my idea of course, but people have been using anaerobic bacteria to fight cancers. Results are mixed but apparently some strains of bacteria look for environments with hypoxia (they are anaerobic after all) and not much immune-cells activity (as tumours often produce factors to suppress the immune system response). The result is that most of them end up going to the tumour and eating the tumour cells. Some researchers think that antibiotics and boosting the immune system should suffice to get rid of the bacteria once the tumor cells have been used as bacterial food.

Another option is to use viruses, and that is the type of research reported here. This highlights one of the problems of recruiting external organisms to fight your own rebels: the immune system still considers them foreign so they will fight them whenever they have the chance. How do you help the virus without compromising the immune system? It would definitely not be wise to help the virus fight the cancer then to find no way to fight the virus. In this particular case the virus success is its downfall. Unfortunately it happens before it manages to completely kill the cancer. What happens is that as the virus attacks the tumour, the tumour cells produce angiogenic factors that stimulate the production of new blood vessels with the result that the immune system comes in and kills the virus. These results suggest that a viral therapy combined with an anti angiogenic one might just give the virus enough room to finish the job and completely kill the cancer.

Overall, it looks to me as if these strategies could be one of the better ways to treat cancer. In other ecosystems there have been attempts to control one species by introducing artificially another one to keep the original species in check. This has been successful many times but, if done carelessly, could backfire and double the amount of trouble. Nobody has ever said that aiming at a moving target is easy!