In 2011, a 52-year-old runner and yoga enthusiast walked into the office of Monica Loghin, a neuro-oncologist at MD Anderson Cancer Center in Houston, complaining of numbness and weakness in her lower limbs and difficulty controlling her bladder.
The symptoms were of grave concern, as the patient had previously undergone surgery for breast cancer that had spread to her brain. If such a cancer returns post-surgery, that is often a sign the patient doesn’t have much time left.
An MRI confirmed that the breast cancer had again spread to the woman’s cerebrospinal fluid. Loghin ordered testing of that fluid to see if the patient might have certain biomarkers that could be targeted by existing drugs. (A biomarker is a DNA sequence or protein associated with the disease; different biomarkers can suggest specific treatments, depending on the disease and other factors.) She asked for tests that could detect tumor cells circulating in the blood.
The cancer cells in the fluid bathing the woman’s spinal cord and brain chambers did, in fact, have a lot of the protein that controls a glucose (sugar) transporter that drives cancer cells. The cancer cells in the fluid also had a lot of HER2, a protein associated with aggressive breast cancers but also treatable with a drug called Herceptin (trastuzumab). The drug is usually taken intravenously, but Loghin had heard of a couple of cases in which Herceptin was delivered directly into the cerebrospinal fluid via a flexible tube, or catheter. The patient agreed to this experimental treatment.
It took only a week for the news to improve. After the first infusion of Herceptin, the patient’s cancer numbers were down. Within a few weeks, her cancer cell numbers had fallen so low that her immune system had begun to take over, clearing out the remaining cancer cells. Nearly two and a half years later, the patient is still alive and well enough to do yoga. Another MD Anderson patient who had a similar disease profile and therapy is also alive and well one year after treatment.
This case outlines the dream of personalized medicine: A disease is analyzed at the molecular level. The analysis identifies a drug target. The drug gets delivered where it needs to go. The patient gets better. And while this hopeful scenario has yet to become commonplace, it is becoming more and more the norm for many breast cancer patients.