An interview with David Persing, MD, PhD, executive VP and chief medical and technical officer
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In the early 1990s, David Persing, MD, PhD, founded and oversaw the molecular microbiology lab at Mayo Clinic, Rochester, Minn, which pioneered many diagnostic techniques used in molecular pathology labs. He joined Cepheid, Sunnyvale, Calif, in 2004, where he leads efforts to fully automate the complex processes behind real-time molecular diagnostics so scientists, clinicians, and those with little training can tap the technology. The on-demand molecular diagnostics company develops and manufactures fully integrated systems and tests for genetic analysis. CLP recently caught up with Persing, who distilled his wide-ranging experiences into timely observations about where his company fits in the supply-and-demand food chain.
Q: How long were you director of Mayo Clinic’s molecular microbiology lab?
A: For about 10 years. I was recruited in 1990 to set up molecular diagnostic testing for the infectious disease diagnostics activity. The microbiology laboratories at that time were just starting to get into molecular techniques.
Q: Describe some diagnostic techniques pioneered by the lab that play a key role in molecular pathology labs today.
A: We were early adopters of PCR technology for routine use in the laboratory. The big concern back then was that of contamination problems with PCR. PCR was viewed as incredibly powerful, but essentially a technique that could not be tamed for routine laboratory use—because of the fact that during the process of performing PCR you create billions or trillions of copies of your target sequence that you’re amplifying to use to identify a particular organism. I spent the first couple of years at the Mayo Clinic figuring out ways to control the technique and make it usable as a routine laboratory method.
Q: You joined Cepheid as a director in May 2004, and became executive VP and chief medical and technology officer in August 2005. What is your role there?
A: When the opportunity came up to come in and reorient Cepheid from a biothreat company to a clinical diagnostics company, I jumped at the chance. What Cepheid has done is they’ve essentially taken my 4,000-square-foot laboratory at the Mayo Clinic with multiple rooms and separation between rooms and lab techs—all the stuff that we did within that PCR facility Cepheid accomplished inside of a little plastic cartridge that carries out all of the sample-processing steps. Nucleic acid extraction, purification, amplification by PCR is all carried out in a disposable cartridge that runs in a system called the GeneXpert, which is the automated instrument platform that all of our tests run on. Testing was so sophisticated it couldn’t be done in your average hospital, and we thrived on this reference lab model. But I saw the Cepheid technology is essentially producing a trend in the opposite direction where you can take this very sophisticated technology with no compromise in performance—you could decentralize the whole process and make it possible for virtually any hospital anywhere at any time to run these tests.
Q: Have you snagged FDA approval?
A: All of our clinical diagnostics either have gone or will go through the FDA approval process. Right now we have three FDA-approved products on the market. We hope to see two more by the end of the year.
Q: Why did you align yourself with the company?
A: Because of the chance to really make a difference in diagnostics. One test that I think is going to have a huge impact is for MRSA testing. Our test is designed to identify a carrier of MRSA rapidly and to minimize exposure of that individual to other hospital personnel by virtue of instituting infection precautions—barrier precautions, contact isolation quickly.
The other area I’m really excited about is a program we’re working on with a group called FIND (Foundation for Innovative New Diagnostics), which is funded by the Bill and Melinda Gates Foundation for the development of a rapid, extremely sensitive diagnostic cartridge for tuberculosis. Now, TB takes weeks or months to grow in the laboratory, and then if you really want to know if it’s one of the bad TB strains, one of the multi-drug-resistant TB strains, you have to wait for a couple more weeks to be able to do drug-resistance testing.
We developed in the GeneXpert, with support from the NIAID (National Institutes of Allergy Infectious Disease) and the Gates foundation through FIND, a cartridge that goes straight from a sputum specimen to a definitive TB result within 90 minutes. It does that in a way that allows us to predict drug resistance as well, so it gives us two things—the identification of tuberculosis and the likelihood of drug resistance—very rapidly, so the patients can be identified at the clinic door as being carriers of TB, placed in the appropriate conditions for reducing the risk of transmission, and they can be given the right drugs without waiting for months for a drug-resistance result, which in current conditions often translates into a postmortem diagnosis.
Q: How are you working on improving microRNA identification and analysis by combining bioinformatic approaches and updating your database to detect all microRNA sequence and antisense targets with in-house-developed methodology?
A: About 2 years ago, we bought a company in France called Actigenics. It specialized in the development of bioinformatic techniques for predicting the presence of microRNA in the human genome, and we’ve been looking at microRNA as a unique diagnostic opportunity for developing novel diagnostic applications in areas like inflammation and oncology. We’re focused heavily on discovering these microRNAs, characterizing them, and exploring their diagnostic value in panels of microRNAs that are measured by real-time PCR on our GeneXpert platform. The idea is to develop gene-expression profiles of microRNAs that are informative, that help make these decisions that I talked about relative to choice of therapy, whether to treat or not to treat, whether to use chemo or not to use chemo. These kinds of decisions are, we think, ultimately going to be resolved and facilitated by gene-expression profiling, and we think the microRNAs are going to have a big impact on the overall tests of the programs to stratify patients according to appropriate therapeutic options.
Q: Describe some industry trends.
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A: I see the industry trends in automation moving toward larger systems. Higher-throughput systems, but still batch-based systems. That’s great for the 12 laboratories in the universe that really need that level of throughput, but it doesn’t really meet the needs of your average hospital of 150 beds that’s 50 miles away from a major metro area. We have to get away from the central lab mentality, which is based on huge central-lab systems, because in order to get enough samples to justify having one of these instruments you have to transport samples across long distances in a reference lab model. There’s a lot of interest now in improving turnaround time by decentralizing the technology.
Q: What is the future of the industry?
A: Molecular diagnostics is the largest growth area for diagnostics. We’re going to see more drug companies building companion diagnostics into their products. We are going to see a lot more pharmacogenetics. The last thing a drug company wants is for their drug to be held hostage to a diagnostic test. Nobody wants to wait around for 2 days for a result when a prescribing decision is in the balance.
JUDY O’ROURKE IS ASSOCIATE EDITOR OF CLP.
