Blog | Wednesday, June 25, 2014

Deadly virus meets deadly cancer with hopeful results

The history of the first hundred years of cancer therapy is that of a war, pitting bigger surgeries and stronger poisons against tumors, with patients caught in the middle. Over the last 2 decades, researchers have found ways of fighting cancer more precisely. One of the most successful examples is that of Gleevec (NYSE:NVS). Chronic myelogenous leukemia (CML), a kind of blood cancer, had been a tough disease to treat, even after the discovery of the genetic quirk responsible for its devastation. In the 90s, researchers discovered a chemical that specifically blocked the molecule produced by this abnormal gene and were able to treat CML specifically and effectively with a pill that caused minimal side effects (compared to traditional therapy).

The road to a unique cure for every cancer hasn’t been smooth–many cancers are much more complicated than CML, having many genetic abnormalities and other characteristics that make them hard to treat. As physicians we usually fall back to what we know: bigger surgeries, nastier drugs. But the search continues. This week, the Mayo Clinic reported two cases of another blood cancer that shrunk with a unique therapy: measles.

Measles can be a horrific childhood disease, but the virus has some interesting properties. Researchers have been able to modify the virus in 2 important ways: first, the virus can be made to latch on to a certain molecule on the surface of cells. Second, it can be made to suck up medical-grade radioactive iodine, making it easy to track with the right instrument.

The research that helped create the modified virus used the HeLa cancer cell line, derived from a woman from Baltimore named Henrietta Lacks, the subject of an excellent book by Rebecca Skloot. Mrs. Lacks died shortly after “donating” her cells, and her family never heard the full story of her contribution to science until Rebecca helped publicized it, leading to important discussions of medical ethics and law.

Multiple myeloma (MM) is a nasty disease which can shut down normal blood cell production, produce proteins toxic to the heart, kidneys and other organs, and create painful tumors in bone and soft tissue. It can often be treated for a while, but is rarely cured.

The team at Mayo came up with a clever idea: could the modified measles virus, which likes to kill cancer cells, be made to kill specific cancer cells? As luck would have it, the virus (called MV-NIS) is particularly attracted to a cell surface molecule that MM makes a lot of.

They found 2 patients, both of whom were dying of myeloma, having undergone all of the most rigorous therapies available. Both patients showed little immunity to measles, meaning they were less likely to fight off the virus before it could get to the tumors (although an argument might be made that the immune response could kill off infected tumor cells, but that’s not what this study looked at).

The 2 patients were enrolled in a “Phase I” trial, the sort of experiment in which no promises are made of any success. It is simply an experiment to see if the patients can tolerate or even survive a new treatment. These patients did, sort of. After being given large doses of the modified measles virus, they developed very high fevers and low blood pressure, but survived this “septic” phase. In one patient, tumor masses melted away and she had a complete remission that lasted about 9 months. The other patient responded to the treatment but only incompletely.

This study exemplified scientific cleverness on several levels. A nasty virus was altered to make it less harmful to normal tissue (it seemed not to infect normal tissue around tumors). The virus was also altered to suck up iodine so that it could be tracked by external scans. As a bonus, radioactive iodine sucked up by the virus can kill tumor cells by zapping them with radiation.

This is a promising proof of concept, but a very early one. This has been tried in 2 patients, neither of whom are cured, and the therapy was not without dangers. Many experts (and laypeople like Mrs. Lacks) contributed to each step that led to this therapy. This may be a promising treatment, or perhaps just one more step toward an eventual treatment. Either way, it’s good science.

Peter A. Lipson, ACP Member, is a practicing internist and teaching physician in Southeast Michigan. After graduating from Rush Medical College in Chicago, he completed his internal medicine residency at Northwestern Memorial Hospital. This post first appeared at his blog at Forbes. His blog, which has been around in various forms since 2007, offers "musings on the intersection of science, medicine, and culture." His writing focuses on the difference between science-based medicine and "everything else," but also speaks to the day-to-day practice of medicine, fatherhood, and whatever else migrates from his head to his keyboard.