At first glance, a Positron Emission Tomography scanner looks just like an MRI or CT scanner. But obtaining images is a little more complicated in PET.
Before undergoing the scan, patients are injected with a glucose solution tagged with radioactive nuclides, or tracers. Once the solution is circulated through the body, which takes about an hour, the patient is placed inside the scanner which constructs a three-dimensional image based on gamma rays set off by the emission of positrons from the tracers in the solution.
The area of interest for most PET scans has been cancer. Since tumors thrive on glucose to grow, their comparatively greater uptake of glucose solution with radio tracers allows for very detailed images.
As the acknowledged technology platform for oncology, the only approved compound for PET imaging has been for cancer patients.
But change is in the air.
Thijs Spoor is confident that the new compounds his company is developing will soon allow PET scanners to do for cardiologists what they’ve done for cancer specialists.
Spoor, a nuclear pharmacist by training, is Chairman and CEO of FluoroPharma Medical, Inc. (OTCQB: FPMI), which is designing and testing two new PET imaging agents to assess patients with cardiovascular disease, a potentially huge market.
Imaging in cardiology is mostly done by CT scans, ultrasound, or SPECT (single photon emission computed tomography). PET can offer unique advantages compared to each, according to Spoor.
The PET scanner can do more, it can see more with the right diagnostic. And that’s where Fluoropharma hopes to make its mark.
Cancer as a disease state has paid for installing the vast majority of the PET infrastructure in the U.S., said Spoor. So the platform is ready to expand in applications. “You have cyclotrons across the country that make the isotope that’s used for imaging (for cancer patients); you have PET scanners in every major hospital–there’s about 2,500 across the U.S., and they do about two million reimbursed PET procedures for oncology.”
The company is currently in Phase 2 clinical trials for the compounds, or radio tracers, which it hopes to bring to the market by 2016.
BFPET (blood-flow PET) is designed to measure cardiovascular blood flow to detect coronary disease in patients as they undergo stress tests. The potential population: 12 million patients.
BFPET is a positively charged lipid, Spoor told me. It will cross the cell membrane because it’s fat soluble (lipophilic). And because it has the positive electric charge, it will be driven by a kind of static cling feature. “So you can determine how much blood flow the heart tissue is getting,” he said.
For patients or providers concerned about radiation exposure, BFPET uses just one-third the radiation dose that the current compound (Technetium) for SPECT requires, and it has the potential to yield higher image quality than SPECT in the same application, due to the higher physical energy of PET-emitters.
“It’s important to determine if the heart has adequate blood flow,” said Spoor. “It’s also important to know what the muscle can do with it once it has blood flow–and that’s where we have the potential to offer better value–with superior imaging.”
For example, he said, in cardiac imaging, you can have complications if there are ‘holes’ in the cross sections of images taken during stress tests using SPECT. Described as ‘false positives’, they can be interpreted as absence of coronary flow in specific regions; more false positives could mean more unnecessary procedures later, and at higher cost to the system.
Compared to SPECT, PET with BFPET brings you from 10mm resolution down to 3mm resolution, said Spoor. Generally, clinical studies have shown SPECT at 70% accuracy versus 85% accuracy for PET overall .
Reaching the Cardiologists
Spoor knows that in addition to getting the new compounds approved, Fluoropharma has to convince doctors that the properties and the imaging resolution will make a real difference in clinical imaging. Nuclear cardiologists, numbering about 5,000 in the US, said Spoor, know they’re at their limits with what they can do with SPECT. “Our market research indicates that forty percent of their new patients could be better served with PET than SPECT,” he added.
Another issue that will cause complications for SPECT imaging: there could soon be more frequent shortages of Technetium, the isotope most commonly used for the SPECT platform. The daughter product of a reactor-produced isotope called Molybdenum, it comes from 2 reactors in Canada; which are scheduled to be shut down in 2016. These reactors are currently responsible for a significant percentage of the global supply of Molybdenum. This means periods of shortage are more likely, potentially coupled with increased expense and longer waiting periods for patients who may not be able to afford to wait longer for testing.
Technetium has a useful energy level, and it can be mixed with stable compounds to optimize imaging for the heart and many other organs. It’s been the standard for most Nuclear Medicine procedures..
There are approximately 450 nuclear pharmacies across the U.S. that compound Technetium doses daily for SPECT imaging–and it has to be used every day because it decays, or breaks down, said Spoor.
Technetium doses have a physical half-life of 6 hours, he added. “Its energy is going to disappear within half a day.”
Clinicians want more options.
Fluoropharma is also conducting a Phase 2 clinical trial for CardioPET in Belgium.
CardioPET is designed for the detection of coronary disease in acute and chronic heart disease in patients who cannot undergo stress testing. There are 17 million potential patients in this market, according to Spoor.
The compound allows the PET scanner to detect regions of fatty acid uptake, which the heart uses as its main source of energy. This system switches to glucose metabolism when blood flow is compromised.
Ultimately, there are two ways to look at Fluoropharma’s approach to the PET market, Spoor said. One is from the technology platform, and one is from the unmet medical need.
“And I think they both intersect, and we have to have a mindset for both of these; if you’re just dealing with a cool technology and trying to find a home for it, then it’s going to be difficult in medicine. When you present this new compound and the physician says, ‘Well, so what?’ you need to be able to answer that question.”
Cardiology is 60-70% of all imaging procedures, over the past 25 years. And it’s key for four reasons, said Spoor. You have established medical therapies: therapeutics and risk factor modification, angioplasty, coronary bypass grafting or heart transplant based on your results.
But the cardiologists need to get the diagnosis right, up front. That’s where Spoor hopes Fluoropharma’s two compounds will make all the difference. (A third compound has yet to enter clinical trials.)
Fluoropharma is not alone in pursuing this market. Lantheus Medical Imaging will compete with them with their own cardiac blood flow compound, Flurpiridaz F18, although preliminary results in their Phase 3 trial suggests that Fluoropharma may have a chance to catch up with them.
Spoor thinks the competition will be good for both companies.
“It helps to have a Coke and Pepsi War at the start,” he said.