Personal Treatments for Your Unique Tumor

In a recent study in Science reviewed here, human immunologist Beatriz Carreno of Washington University in St. Louis and her coworkers have used a patient’s own immune system against their cancer cells. It is too soon to know whether the treatment can cure patients or not but the patients in the study did tolerate the treatment well and their immune systems responded appropriately.

Now this isn’t a big deal because they used the patient’s immune system to attack cancer. Heck, the prostate cancer treatment Provenge has been on the market since 2010 and it uses the same idea.

No, what makes this approach so important is that it has the potential to become a treatment for lots and lots of different cancers. It could turn out to be chemotherapy without the hair loss and nausea.

Potentially Transformative and Punishingly Expensive

The authors in this study analyzed three different patients’ tumor cells and found a unique set of triggers for each patient that they used to activate their immune systems. Each patient received an individualized treatment tailored to their own tumor.

If this all works out, there is no reason to think that a similar approach couldn’t be used for most anyone’s cancer. This study might be showing us the way to a truly personalized medicine in which each patient has their own unique treatment with minimal side effects. Or, then again, maybe not.

Even if it works, a personalized treatment like this will almost certainly be breathtakingly (or maybe more appropriately breath-givingly) expensive. The much simpler treatment Provenge costs over $100,000. A treatment based on this approach will cost even more because it is so much more complicated.

And there is no guarantee that it will be particularly effective either. On average Provenge gives patients an additional 4 months or so. It is possible this new treatment could be better but then again it might not be.

Still, the convergence of cheap DNA sequencing and a better understanding of how the immune system works has opened the door to new treatments for cancer. Even if this treatment doesn’t work, we still may use our newfound knowledge to dream up newer, more precise treatments.

Cancer as Other 

We can get our immune systems to recognize tumors because cancer cells have changed so much from what they originally were that they are almost as foreign as bacteria or viruses. And our immune systems know what to do with foreign cells. They find and destroy them.

Unfortunately cancer cells aren’t quite foreign enough for our immune systems to recognize them on their own. This is why we need scientists to give our immune systems a gentle nudge in the right direction. They do this by using the cancer cell’s mutations against itself.

Cancer starts out as a cell that gets a few mutations in its DNA that cause it to either grow uncontrollably and/or refuse to die. Then, because some of these mutations also make the DNA in these cells less stable, more and more mutations happen as the cancer develops.

This is why each person’s cancer is unique. Each person’s cancer has a distinct set of mutations that depend on what happened to the cell’s DNA after those first few critical mutations.

This is also why the scientists in this study needed to create unique treatments for each patient. The three patients did not share the same set of mutations that were useful for the therapy and so could not be treated in the same way.

If this approach works, it could be a game changer for cancer vaccines* like this. They will be able to be used by many different patients with a wide range of cancers.

*Cancer vaccine is the current name for these treatments but it isn’t great. Vaccine implies that it will prevent the cancer from happening if you take it but it does no such thing. A better term is probably immunotherapy.

Not Your Uncle’s Cancer Vaccines

As I said, there is a similar product on the market, the prostate cancer treatment Provenge. With Provenge, every patient’s immune system is activated with the same prostate-cancer specific trigger. What makes it personalized is that each treatment uses a patient’s own immune cells.

This approach is different in that it adds an additional layer of personalization. Each patient’s cells are activated by a set of triggers unique to their particular cancer. This is a much more complicated undertaking than Provenge.

Scientists first need to read and compare the DNA of the cells of the patient and the cancer. Then they need to identify the key differences between the two and convert them into a set of triggers that can be used to program the patient’s immune cells to recognize the cancer cells. While this is getting cheaper and easier, it is still no picnic. It takes a lot of time and money to pull off.

After this part, it is pretty much the same as with Provenge. The right immune cells are removed from the patient and put in a dish. Then the immune cells are exposed to the triggers, grown up in the dish and then put back into the patient. Then, if everything is working right, the patient’s immune system seeks out and destroys any tumor cells it finds.

This is obviously nontrivial! But still, given how cheap DNA sequencing has become, it is certainly doable. Now we will have to wait and see if it is effective and affordable.

A lengthy but very complete description of this approach to making cancer vaccines: