Chemotherapy – Targeting

In my most recent (I don’t use “last” anymore) post, I mentioned the 4-phase cell cycle and suggested that tumor cells are most sensitive to chemotherapy in the G1 and M phases. Sounds like a logical approach to targeted treatment would include identifying the cell state and treating it when it is most sensitive. Logical, but unfortunately not practical, as cells don’t cycle through their phases in lockstep and the time span of each cycle will vary and be too short to be useful.

So what can be done to improve targeting? Virtually all of the newest research is focusing on DNA/RNA for the answer. Preliminary results suggest that the genetic structure of a person’s cells, especially tumor cells, can provide valuable information about how to attack cancer for a specific individual, as well, more general approaches.

Targeted therapies, which include cell growth inhibitors and immunotherapy, are emerging as a fourth approach, different from chemotherapy. A distinction being made is that traditional chemo- is a “chemical approach to a biological program,” where as targeted therapies can be characterized as a “biological approach to a chemical problem,”

Although there is a growing belief that traditional chemo is more limited in what can be achieved than targeted therapies, there are still benefits to be gained from genetic research, especially in choosing the most appropriate chemical approach and avoiding more harmful ones. It is likely, therefore, that genetic profiling will become one of the baseline tests for cancer treatment. Lobby you insurer and Congress folk to make sure it is covered by private insurance, Medicare, and Medicaid – it’s not cheap yet.

Truth in advertising – genetic profiling is a powerful tool in the fight against cancer. Unfortunately, in order to be most useful, tumor cells must be present and accessible. For example, when I had my first episode of a very small tumor in my lung, it was removed surgically. At that point, I was “NED” – no evident disease. Shortly thereafter a promising clinical trial opened up, but I was ineligible because you must have detectable, observable tumors so the clinician-researchers can determine the effect of the treatment being tested. For a melanoma patient, this is particularly frustrating, because you know the mutated cells are there, they’re just too small to be detected.

Again, within the last month, a new trial for an immunotherapy agent was announced. This time, with tumor aplenty, I am still ineligible because the lesion must be on the skin or sufficiently close under the skin so it can be accessed physically and fairly frequently. Mine are out of reach without significant surgical damage – ineligible.

In my next post, I will have more to say about traditional chemical approaches and how it is being modified by new knowledge.

Pip pip – stiff upper lip.