Two for One
Neuroendocrine cancer is rare and hard to diagnose – and it can be difficult to treat and to survive.
Its tumors can disrupt the body’s hormones and food transit through the bowels, causing an array of nonspecific symptoms that may not be diagnosed before the cancer spreads. The number of people affected keeps rising: more than 12,000 people in the United States were diagnosed with neuroendocrine cancer last year.
“Patients can have this disease for several years before they find the cause of their symptoms,” says Heloisa Soares, MD, PhD, an expert on neuroendocrine cancers who leads the gastrointestinal multidisciplinary team at The University of New Mexico Comprehensive Cancer Center.
To help make more accurate diagnoses more quickly, the UNM Department of Radiology recently started using a new, injectable imaging agent to pinpoint neuroendocrine tumors. And in October, UNM Cancer Center will begin offering a new treatment that uses part of that imaging agent to fight the tumors.
“It’s called a theranostic,” says Joanna Fair, MD, PhD, a doctor of radiology and nuclear medicine, and a member of UNM Cancer Center’s gastrointestinal multidisciplinary team. “It’s a combination of diagnostic and therapeutic nuclear medicine. You take the agent used for imaging and attach a different radioactive atom to make a therapy agent.”
The new imaging agent works its magic thanks to a molecule called dotatate, which binds to a site on a cell’s membrane called a somatostatin receptor. Neuroendocrine cancer cells have many more somatostatin receptors than healthy cells, so dotatate molecules cluster on those cells. The dotatate molecule is bound to a radioactive gallium-68 atom that lights up the cancer cells on a positron emission tomography/computed tomography (PET/CT), scan.
“Gallium-68 dotatate is more sensitive than what we were using in the past,” Fair says. “Our ability to make the diagnosis is better.” The radioactive gallium atoms deliver sharper tumor images and the new imaging agent requires only one visit (older imaging tools took several visits over a few days).
A new drug, called Lutathera, combines the dotatate molecule with a different radioactive atom – lutetium-177 – which emits radioactive beta particles. As the dotatate concentrates the lutetium-177 in the neuroendocrine cancer cells, the beta particles kill them. Beta particles don’t travel far inside the body, though, so only a few cells closest to the drug receive radiation, too.
Lutathera was approved by the Food and Drug Administration in January. According to Soares, a recent study in people with midgut cancers showed that tumors shrank in 18 percent of those given Lutathera, something rarely seen with other neuroendocrine therapies. Additionally, the Lutathera therapy provided a 79 percent reduction in risk of disease progression or death in comparison to people given the standard octreotide high-dose therapy.
Soares and Fair are quick to caution that every drug carries risks, and Lutathera is no exception. It is given as an infusion, along with amino acids to protect the kidneys. Each of the four infusions can take as long as eight hours and some people have side effects, such as nausea, from the amino acids. It also carries a small risk for leukemia and toxicity in the kidneys and liver.
Still, the majority of people who face neuroendocrine cancer may accept these risks, Soares says. Soares, Fair and their team already offer gallium-68 dotatate imaging. They plan to offer Lutathera in October as just one of the treatment options for their patients to consider.
Heloisa Soares, MD, PhD, is an assistant professor in the Department of Internal Medicine, Division of Hematology/Oncology, at the UNM School of Medicine. She is the section leader for the Hepatic, Pancreatic, Biliary and Neuroendocrine Tumors Clinical Program and leads the Gastrointestinal Multidisciplinary team at the UNM Comprehensive Cancer Center. Soares is an expert on neuroendocrine cancer treatment. You can follow her on Twitter @helops79
Joanna Fair, MD, PhD, is an associate professor in the Department of Radiology and associate dean of Graduate Medical Education at the UNM School of Medicine. She is a radiologist and nuclear medicine physician and a member of the Gastrointestinal Multidisciplinary team at the UNM Comprehensive Cancer Center. Nationally, Fair serves as a director and vice chair of the American Board of Nuclear Medicine.