Black men die more often of prostate cancer yet, paradoxically, have greater survival benefits from immunotherapy treatment. A new Northwestern Medicine study has discovered the reason appears to be an increase of a surprising type of immune cell in the tumor. The findings, published in Nature Communications, could lead to immune-based precision medicine treatment for men of all races with localized aggressive and advanced prostate cancer.
In the new study, Northwestern scientists showed tumors from Black men and men of African ancestry have an increased proportion of a special immune cell called plasma cells compared to the tumors of white men. A research team lead by Edward Schaeffer, MD, chair and the Edmund Andrews Professor of Urology and a Northwestern Medicine urologist, found this increase in plasma cells correlated with improved cancer survival following surgery and identified plasma cells as potential drivers of prostate cancer immune-responsiveness.
“If a man’s prostate cancer has numerous plasma cells, we found he had improved cancer survival,” said Schaeffer, who is also program director of the Genitourinary Oncology Program at the Robert H. Lurie Comprehensive Cancer Center of Northwestern University. “Our study suggests plasma cells are important in the body’s response to cancer.”
Although recent research suggests Black men with advanced prostate cancer have improved survival outcomes with immunotherapy, there has been no way to predict which individual patients — Black or white — with prostate cancer may respond best to immunotherapy drugs.
Schaeffer’s team explored this by analyzing the genomics of 1,300 tumor samples annotated with self-identified race or genetic ancestry. They found, on average, more plasma cells in Black men’s tumors than white men’s.
The finding was not unique to Black men, and the work showed that in all men with elevated plasma cell levels there was improved cancer-free survival following surgery.