Dr Scott Paulson: Role of Somatostatin Analogs, Biomarkers in Treatment of GEP-NETs
Somatostatins have been the most game-changing drug in the treatment landscape of gastroenteropancreatic neuroendocrine tumors, explained Scott Paulson, MD, co-director of the Gastrointestinal Research Program for The US Oncology Network, medical director for the Neuroendocrine Research and Treatment Center at Baylor Charles A. Sammons Cancer Center, Baylor University Medical Center.
What role do somatostatin analogs play in the treatment of gastroenteropancreatic neuroendocrine tumors?
I’d say it’s probably the most central pharmaceutical in the treatment of these tumors. I think it’s probably been the most game-changing drug as far as the landscape’s concerned, over the last 20 years. They’re fairly low toxicity drugs. Their biggest toxicity is really that they’re costly and they’re monthly, so they require a little more effort out of the patients and that they’re going to have to continue to come in for monthly injections. But, they’re still going to be the most central pharmacologic agent and, often time, our best tool in the toolbelt, if you will.
Are there any patient characteristics or biomarkers that indicate response to treatment?
So, there’s a lot of things that are being looked at. Centrally, I think imaging is playing a bigger and bigger role, even in the community-based setting. So, things like DOTATATE PET/CT, 68Ga-DOTATATE PET/CT, has really changed the way that we look at it because you can get a much more comprehensive biomarker of the entire tumor by dong some nuclear imaging, and that gives you an idea of what receptors light up and what drugs you may be able to use and is an appropriate indicator of how well things like peptide receptor radionuclide therapy (PRRT) will work.
Whether it’s a really appropriate indicator of how well things like somatostatin analogs will work is still a little matter of debate. That evidence is not nearly as robust. But, that gives you a pretty good comprehensive picture of the tumor. There has been a lot of look at SSTR2A, which is a marker on the outside of the cells that they can stain for pathologically and how that’s being linked for responses to therapies is certainly being used as criteria for a couple of clinical trials at hand.
And then, the biggest indicators are classically what we’ve always used to just grade these things pathologically, which is what do they look like under a microscope, how aggressive do they look, what is the Ki-67, which continues to be an extremely useful prognostic tool. Those types of factors are still, I would say, the most central things that we use to try and make treatment decisions up front.