Latest in precision cancer medicine
Prof Richard Schilsky - Chief Medical Officer, ASCO
I think we just heard three interesting studies presented about the emerging role of precision medicine in taking care of cancer patients. The first one was a large study of the potential role of so-called liquid biopsies in the management of cancer patients. So a liquid biopsy essentially is a blood test that measures the amount of tumour DNA that’s circulating in the blood stream. This is a kind of a test that’s emerging now to monitor both the amount of tumour DNA in the blood but also the mutations that are present in that DNA with the goal of ultimately potentially replacing the need in many cases for doing a more invasive and more risky tissue biopsy which is what is typically done these days to look at the mutational profile of many kinds of cancer. The study provided important information, a large study – more than 15,000 patients, basically showed that the genomic abnormalities present in those circulating tumour specimens were very similar to what one would expect based upon large data sets where the mutations were analysed in tumour tissue obtained from patients. The potential advantages of doing the circulating tumour DNA test are that it’s quick, it’s easy, it’s relatively painless, you can do it repetitively and it can be used to monitor the overall course of a patient’s cancer because the cancer does change over time and in response to treatment. So it’s a promising new technology; the study presented provides important data to move it along in its development towards greater clinical acceptance and I’m sure it will find its place in the management of cancer patients.
The second study we just heard presented, sponsored by Genentech, the so-called MyPathway study, again is looking at the concept of treating tumours based on their genomic profile rather than the histological type or the pathological diagnosis obtained by looking at the tumour under the microscope. So in that study patients with a variety of kinds of advanced cancer had testing done on their tumour to determine whether or not specific mutations were present and if certain mutations were present they were then eligible to be treated with a targeted therapy that’s already FDA approved for use in a certain tumour type but not necessarily in their tumour type to see whether or not using the drug against their tumour with the genomic target of the drug produces some benefit. Again the results are very encouraging, I think the most encouraging aspect of it was in patients with tumours that have abnormalities in the HER2 gene. This is a gene that we know to be abnormal in many women with breast cancer, there are standard and effective therapies available for it, most notably the drug Herceptin, but we don’t know whether or not drugs like Herceptin work if the HER2 gene is abnormal in another kind of cancer. What the investigators reported this morning is that in a substantial fraction of patients whose tumours have a HER2 abnormality that in fact those patients do respond to treatment with drugs like Herceptin that target the HER2 gene. So the most promising results were actually in patients with colorectal cancer. These were patients who were no longer responding to standard colon cancer therapies. A fraction of them had abnormalities in the HER2 gene and about a quarter of those patients when treated with Herceptin actually responded to that treatment. So it opens up the possibility now of treating patients based on the genomic abnormality in the tumour, more so than just on the type of cancer that the patient has.
The third study that we heard about is really a social media experiment about how to recruit patients to participate in clinical research. It’s a study in women with metastatic breast cancer, the investigators were seeking to enrol those women in a research study where the women would contribute their tumour specimen and other specimens into the study. Instead of doing it in the traditional way by going out to the medical community and asking doctors to find the patients, they just went directly to the patient community through social media, through websites, and what they found was a very rapid uptake of patient engagement in the study. Lots of interest, many patients enrolled in a very short period of time. We hear all the time about the fact that a very small percentage of adult cancer patients actually participate in clinical trials, 3-5% is the number typically quoted. The main reason for that, of course, is that patients are either unaware of the opportunity to participate in studies or aren’t given the opportunity to participate. What the study presented this morning demonstrated is that if you go directly to patients, patients are enthusiastic about the opportunities to participate in research, they view it as their contribution to developing better therapies for patients like them who have cancer. So we’re going to see this as an example of how to rapidly accelerate patient participation in clinical research by engaging the patients directly and we’ll find an enthusiastic response.