Imagine looking for breast cancer with a type of “scope” that could accurately diagnose the early stages of the disease. Researchers at Yale Cancer Center are beginning to make this a reality using a diagnostic test called RNAScope to measure the level of programmed death ligand 1 (PD-L1) mRNA in cancerous tissues.
“This is exciting because these findings provide the rationale to test PD-L1 targeted therapies in breast cancer with the hope of further improving cure rates in early stage breast cancer,” said Lajos Pusztai, MD, DPhil, an author of the study published by the team at Yale Cancer Center, in a news release from the Yale Cancer Center.
As detailed in a report published in the Journal of Clinical Cancer Research, entitled, “In Situ Tumor PD-L1 mRNA Expression Is Associated with Increased TILs and Better Outcome in Breast Carcinomas,” the team studied 636 prepared stage I-III breast carcinomas in two tissue microarrays (238 in YTMA128 and 398 in YTMA201). Each was probed for in situ PD-L1 mRNA. Presence of lymphocytes was also quantified after staining the tissues for cells.
A little over half of each group (55.7% in YTMA128 and 59.5% in YTMA201) was positive for PD-L1 mRNA. Tissues with the highest PD-L1 mRNA expression were associated with the highest number of infiltrating lymphocytes and the longest recurrence-free survival. Having more lymphocytes was also associated with estrogen receptor-negative status.
Overall, the researchers concluded that PD-1/PD-L1-targeted therapies may be useful in battling breast cancer. “Patients with many tumor infiltrating lymphocytes and high PD-L1 expression may be the ideal candidates for these therapies,” said Dr. Pusztai.
PD-L1 is a protein important in immune suppression. In the context of cancer, PD-L1 allows tumors to survive during an immune attack. Since PD-L1 predicted better survival in patients, there may be a beneficial role of the immune system in controlling breast cancer.
