Pancreatic cancer is one of the most common causes of mortality worldwide. In a recent study, researchers at Okayama University have reported on a method for classifying the PD-L1 status of patients diagnosed with pancreatic cancer.1 Such classification is necessary for determining whether the patient can benefit from immune-checkpoint inhibitors, a new class of drugs that have recently been developed to combat the condition.
To impede the growth of cancer, immune-checkpoint inhibitors such as atezolizumab or avelumab bind to a protein called PD-L1, which is found on the pancreatic cancer cells of certain patients. Determining whether a patient is PD-L1-positive can help clinicians initiate immune-checkpoint inhibitor therapy earlier. However, correctly identifying patients whose tumors express PD-L1 remains a challenge for oncologists. Researchers at Okayama University recently investigated a technique for diagnosing this subgroup of patients.
Kazuyuki Matsumoto, MD, PhD, Okayama University.
In the human body, T-cells are the soldiers of the adaptive immune system. Their ability to battle pathogens is made possible by PD-1, a protein found on T-cells. Normal cells of the body are protected against this scavenging activity by expressing the protein PD-L1, which binds to PD-1 and deactivates T-cells. However, several types of cancer cells have also devised a mechanism to express PD-L1, thereby bypassing the surveillance of T-cells and protecting themselves from attack. Drugs such as immune-checkpoint inhibitors can deactivate the PD-L1 protein so that cancer cells are no longer protected.
A common, minimally invasive method for diagnosing cancer is fine-needle aspiration, an advanced technique that involves sliding a thin needle through the skin to extract suspected cancerous tissue, which is subsequently tested in the laboratory for cancer markers.
In the Okayama study, a research team led by Hiroyuki Okada, MD, PhD, professor of gastroenterology and hepatology, and Kazuyuki Matsumoto, MD, PhD, assistant professor of gastroenterology and hepatology, sought to determine whether fine-needle aspiration is advanced enough to help detect the presence of PD-L1.
Cancer patients often undergo surgery to have their cancerous mass removed. Analyzing such surgically removed cancerous tissues often gives the most accurate depiction of their characteristics. The Okayama study was conducted on such patients who had also previously undergone fine-needle aspiration for diagnosis.
A comparison of PD-L1 (brown coloring) observed in the surgically resected (left) and fine-needle aspirated (right) pancreatic cancer samples.
The cancerous tissues resected during surgery and during fine-needle aspiration were analyzed under a microscope for the presence or absence of PD-L1, and the results were compared. If a patient’s tissue contained more than 5% of PD-L1, the patient was considered PD-L1-positive. The study determined that approximately half of the patients classified as PD-L1-positive—and almost all of patients classified as PD-L1-negative—could be categorized through the use of fine-needle aspiration specimens.
The Okayama study demonstrated the usefulness of identifying a patient’s PD-L1 status at the time of diagnosing pancreatic cancer, and showed that fine-needle aspiration can be useful for facilitating such diagnoses. The researchers conclude that their findings have potential utility in the field of precision medicine for patients with pancreatic cancer. If performed early on, such accurate diagnoses and classifications can help oncologists provide customized treatment to patients and greatly improve their chances of survival.
For further information, visit Okayama University.
Reference
- Matsumoto K, Ohara T, Fujisawa M, et al. The relationship between the PD-L1 expression of surgically resected and fine-needle aspiration specimens for patients with pancreatic cancer. J Gastroenterol. Epub ahead of print, April 29, 2019; doi: 10.1007/s00535-019-01586-6.
