Erica Carpenter, MBA, PhD, Director of the Liquid Biopsy Center at the Perelman School of Medicine at the University of Pennsylvania, explains how liquid biopsy is an innovative and non-invasive way to treat cancer patients.
Interview conducted by Ivanhoe Broadcast News in May 2017.
We met with Kim and it was a lifesaver for her to be involved in this, it’s given her extension of her life and mentally a new perspective. I understand the scientific part of what you run, but from an emotional standpoint as a researcher, how do you feel about that?
Dr. Carpenter: This is why we come to work in the morning. I mean at the end of the day, to hear from a patient’s point of view how the work we do affects their life, perhaps even extends their life, it doesn’t get any better than that on an emotional perspective. To know that we, in this translational area of medicine, are truly able to take what was just a glimmer of hope technologically ten years ago, and move it into the clinical space and actually have it affect our patients? It’s a win-win it doesn’t get any better than that.
In a timeline of what happens, from a germination of an idea, how long does it generally take for something like this to get in to the general population?
Dr. Carpenter: It takes too long.One of the things that we’re trying to do is accelerate the pace of technology translation. So that when we see an idea that actually has clinical merit, in other words; a technology that will help us make better decisions in the clinic, we want to figure out ways that we can accelerate the path so it gets to patients sooner. But, to do that in a methodical and rigorous way so we know that when we do bring it into the clinic it will truly bring benefit to the patient. There are many examples of liquid biopsy that are currently in the clinic. One would be circulating tumor cells. Now this is not the test that we used for Mrs. Belcastro.Circulating tumor cells are something we’ve known about for decades. But FDA approval of a CTC test took years and years to come about. Currently there’s one FDA-approved technology for circulating tumor cells. That’s something that we certainly hope to change over the next few years. Circulating tumor DNA, which is the test that we used for Mrs. Belcastro and many other of our patients here at the Abramson Cancer Center, that’s a technology that went from idea to technology to clinical application faster. As I said, we’re working to actually shorten that time span.
How did Kim come to be involved in this study? Where do you find the participants to recruit for any study?
Dr. Carpenter: I wouldn’t say that she was part of a study per say. The test that she received is one that clinicians here at the cancer center can order as part of standard of care. Any patient, let’s say any lung cancer patient like Mrs. Belcastro, who comes to our clinic, their physician would carefully evaluate then make a decision as to whether that test would add important information to the decision making process. That is done routinely here. We are one of few leading academic cancer centers who provide that.
What does that do for the patient? Does that early diagnosis leading to intervention?
Dr.Carpenter: Using Mrs. Belcastro as an example, I wouldn’t say that this was early detection. The point at which the test was ordered, we knew that she had lung cancer. The question that we were trying to answer was just slightly more refined. What we were trying to figure out was does her cancer have certain mutations we can therapeutically target? Therefore, giving this test at the diagnosis of her cancer allows us to make better decisions about treatment earlier in her treatment.
Specifically what did you find about those mutations and how did that help you to treat her better to actually extend her life?
Dr. Carpenter: While we’ll never know with certainty whether the detection of the mutations extended her life, we actually were able to detect mutations, genetic alterations that were in her tumor that we could find in her blood. In her case we were able to find the one or two very, very small pieces, microscopic pieces of DNA that contained this mutation among billions and billions of other pieces of DNA that were in her blood. The technology is incredible, but the actionability of it in this case was that, that mutation was something for which we have an approved drug, that allowed us to treat Mrs. Belcastro. Then there’s another dimension to her treatment that is also true for many patients here for whom we order this test and that is, we are able to order this test more than once over the course of their therapy. Previously, the only option for us to genetically monitor their therapy, in other words see if they’re still getting benefit from the drug that was prescribed or whether we need to switch to another therapy was through repeat biopsies. Repeat biopsies can be very uncomfortable and even painful for a patient. Some patients simply refuse after the original diagnostic tissue biopsy. But a blood test is performed in the physician’s office. In fact the vast majority, almost a hundred percent of the DNA tests that we perform from blood are done when the medical oncologist is already ordering other blood work. Consequently, there’s actually no additional discomfort to the patient, and it’s at an already scheduled office visit.
These mutations that occur mutate again and again as the cancer grows?
Dr. Carpenter: Right.
So it takes a constant re-diagnosis?
Dr. Carpenter: Yes, it sometimes can. That’s exactly what I’m talking about here. So for many of the targeted therapies that we can offer patients, for whom we detect the mutation in the blood or the tissue, we know that to your point the mutations will evolve over time. Unfortunately, new mutations will evolve. But again we have second and third line inhibitors, in other words other drugs that we can give when we see new mutations arise. The clinical problem is that it’s very difficult to detect that specific mutation by repeat biopsies. We know from imaging, for example; standard of care monitoring through imaging, that a patient may be relapsing. Nevertheless, an image can’t currently tell us whether that mutation is present.
So how often will you continue to do this liquid biopsy say on Mrs. Belcastro?
Dr. Carpenter: It depends on the clinical presentation. We’re able to do them with whatever frequency the patient is visiting our clinic, either to see the medical oncologist or for standard of care imaging.
Where does the germination of the idea for something like this come from? Who gets the light bulb moment?
Dr. Carpenter: At our cancer center the idea always starts from an unanswered and unanswerable clinical question. Rather than the historical perspective which has been, we’ve got a technology, how can we deploy the technology,we like to start with the question, what’s the imminent need in the clinic? Where do we lack information to make better decisions and then what technology, like the circulating tumor DNA technology we used for Mrs. Belcastro, what technology do we have the best answers for that question. That’s the germination of the idea that led to this success with her.
END OF INTERVIEW
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