Genetic engineering? Immunotherapy? These are terms often mentioned in the news, but we don’t totally grasp their significance- especially for cancer victims.
These two techniques are being combined to augment our arsenal against cancers. In this first case, white blood cells- in particular, T cells- are withdrawn from the patient’s blood. The T cells are then modified to amplify their capabilities, then grown in the lab (for 7 to 10 days), only to be re-injected into the patient. These cells are then able to use our own immune system to fight the cancer attacking our bodies.The trick is in combining the T cells with a disabled virus so they produce chimeric antigen receptors (CARs). These CARS are super-sensitive to the malignant proteins that are on the surface of the cancer cells; which means they can then attach to and kill those cells.
It’s not just one company doing this sort of research. Novartis (in cahoots with the U of P), Juno (Memorial Sloan Kettering is their partner), Pfizer, Kite Pharma and Celgene are all entering this pharmaceutical space. Of course, no one knows how long the remission the treatment affords actually lasts. And, there is a big side effect- surge in heart rates and drops in blood pressure (both part of the cytokine release syndrome)- due to the immune response when the therapy is effective against the cancer.
And, let us not forget how expensive this therapy is. This is customized medicine- one drug for one patient. And a complex manufacturing sequence to boot.
That’s why Pfizer is attempting to produce what could be termed a generic CAR therapy- one that works in any human. (Don’t get too excited- this is still preclinical research.)
There’s also another competitive approach. Instead of developing T cells that recognize the cancer cells, folks like Bristol Myers Squibb produce a drug that employs an entirely different approach.
Going after those tumors that have “blockades” or “inhibitors” that prevent our body’s T cells from recognizing and attaching to the cancerous growths is where this other method is aimed. An inhibitor drug (like ipilimumab and pembrolizumab) counteracts these blockades, so the T cell can attach to the tumor and kill it. These sorts of drugs are often termed “checkpoint inhibitors”.
The problem is like the other drugs mentioned above, we don’t know how long they last- which also means we don’t know how long the drug therapy is required. Moreover, the results for this therapy are not uniform. Those who garner significant improvement may do so because of the actual census (how many) of T cells the patient had before therapy or the approach may only work for those patients that produce different sorts of T cells.
Either way, these new therapies are going to be expensive.
(Tomorrow, we’ll consider some of the more radical changes in thought regarding cancer therapy.)
