What’s New in Gastrointestinal Neuroendocrine Tumor Research?

Research is always going on in the field of gastrointestinal (GI) neuroendocrine  tumors. Scientists keep looking for the causes of, and new ways to prevent, diagnose, and treat these tumors.

Research on the genetics of GI neuroendocrine tumors

Researchers hope finding the causes of GI neuroendocrine  tumors can be used to help prevent or treat them in the future. For example, the IPMK gene (the gene associated with a small intestinal neuroendocrine tumor that runs in families) has now been found in people with GI neuroendocrine tumors who might not have a family history of small intestinal neuroendocrine tumors. Other genetic changes that seem to make tumors more aggressive are now being explored as well.

Research on diagnosis of GI neuroendocrine tumors

Because the outlook and treatment of GI neuroendocrine tumors and other cancers of the digestive tract are very different, accurate diagnosis is important. Imaging tests and serum markers like CgA are helping doctors make more accurate diagnoses and develop treatment plans for patients with neuroendocrine tumors.

 Imaging tests

In the past few years, a new imaging test called a Gallium-68 PET/CT Dotatate scan has been approved to look for GI neuroendocrine tumors. This type of imaging can detect specific parts of protein (i.e., somatostatin receptors) found in the cells of neuroendocrine tumor.  This scan appears to find neuroendocrine tumors better than the Octreoscan.  Researchers are looking at other imaging methods for early detection of neuroendocrine tumors.

Biomarkers

In addition to imaging, serum chromogranin A (CgA) is an important biomarker used in diagnosing and monitoring neuroendocrine tumors. Elevated levels of CgA in the blood can indicate the presence of these tumors and are often used to monitor tumor progression or response to treatment. 

Research on treatment of GI neuroendocrine tumors

Surgery is the main treatment for removable neuroendocrine tumors. Sometimes, removing the bulk of the neuroendocrine tumor can also reduce the severity of the carcinoid syndrome. Better treatment approaches are needed when surgery can’t remove all the tumors. Chemotherapy has had limited success. New chemotherapy drugs and combinations of drugs are being studied, but more effective advances are likely to come from other types of treatment.

Targeted therapy

Several newer types of drugs, known as targeted therapies, are now being studied for use against neuroendocrine tumors. Targeted therapies are drugs or other substances that identify and attack cancer cells while doing little damage to normal cells. These therapies attack the parts of cancer cells that make them different from normal, healthy cells. Each type of targeted therapy works differently, but all can change the way a cancer cell grows, divides, repairs itself, or interacts with other cells.

Bevacizumab (Avastin) attacks a tumor’s blood supply and stops growth of tumor blood vessels. It is already being used against other types of cancer and is being studied for neuroendocrine tumors.

Other targeted therapies block the molecules that increase the growth of cancer cells. Some of these are used in other types of cancer and are now being tested for use against neuroendocrine tumors.

The FDA has approved a newer, more improved radionuclide treatment for patients with advanced or worsening GI neuroendocrine tumors that have the somatostatin protein uptake on scans. This treatment uses Lu-177-dotatate (a radioactive substance) which attaches to neuroendocrine tumors with the somatostatin protein and releases small doses of radiation to kill the cancer cells.

Immunotherapy

Immunotherapy uses a person's own immune system to detect and attack cancer cells.  Like other cancer types, immune checkpoint inhibitors, such as ipilimumab and nivolumab, are being studied in people with neuroendocrine tumors.

Another form of immunotherapy, chimeric antigen receptor (CAR) T-cell therapy, relies on T cells to find and destroy cancer cells. Researchers are looking to see if these forms of therapy, either alone or in combination with other proven methods of treatment (i.e., Lu-177-dotatate), would be effective in treating neuroendocrine tumors.