Important clues can be found in routine pathology slides. Immunotherapy drugs called “checkpoint inhibitors” have revolutionized treatment for patients with metastatic clear cell renal carcinoma (ccRCC), the most common type of kidney cancer. But they don’t work equally well in all patients. Which patients will benefit the most?

Hopkins scientists have found predictive clues in a recent study of routine pathology slides of patients’ cancer biopsies. Led by pathologist Julie Deutsch, M.D., the investigators studied three groups of patients with metastatic ccRCC who received checkpoint inhibitors (specifically, anti-PD-1-based drugs). They looked for the presence of immune cells in the tumors (known as tumor-infiltrating immune cells), and dead cancer cells (necrosis).

“We found that patients whose biopsies showed the presence of tumor-infiltrating immune cells and the absence of necrosis had improved survival,” says Deutsch. “This predictive ability was further refined when adding in the presence of a common kidney cancer mutation, called PBRM1.” These findings “will help us in selecting patients for immunotherapy,” says urologic oncologist Nirmish Singla, M.D., M.Sc., who took part in the study.

When the investigators searched the literature looking for biomarkers linked to the success of immunotherapy in these patients, they found limited evidence incorporating pathology slides. “Our findings demonstrate the important information that can be obtained from these slides, and provide support for including slide analysis in biomarker studies.” Their findings were published in Cell Reports Medicine.