Does Small Cell Ovarian Cancer Respond to Immunotherapy?
Posted: Thursday, March 22, 2018
The hypercalcemic type of small cell ovarian carcinoma tumor may respond well to treatment with PD-1/PD-L1 blockade, according to the study findings published in the Journal of the National Cancer Institute. Petar Jelinic, PhD, of the Perlmutter Cancer Center at the NYU Langone Medical Center, and colleagues explored the rationale behind immune checkpoint blockade in this patient population, and their results were unexpected, considering the low-mutation burden of this tumor type, researchers said.
“The findings underscore inconsistencies between mutational burden and immunogenicity, emphasizing the need for additional biomarkers to assess tumor recognition by the immune system,” the researchers concluded.
For analysis, Dr. Jelinic and colleagues collected case histories from four patients who used anti–PD-1 immunotherapy for the hypercalcemic type of small cell ovarian carcinoma. Each patient had at least one large ovarian tumor and underwent complete tumor resection. Using immunohistochemistry, the researchers assessed tumor expression of PD-L1, CD3 (T cells), and CD68 (macrophages) in 11 cases of this type of ovarian cancer.
In 8 of the 11 cases, the tumors demonstrated PD-L1 expression with strong associated T-cell infiltration. The researchers detected PD-L1 expression in both tumor and stromal cells, with macrophages as the most abundant PD-L1–positive cells in three cases.
“The association between PD-L1 expression and T-cell infiltration suggests that PD-L1 expression is likely not intrinsic, but rather a mechanism of adaptive immune resistance to (tumor-infiltrating lymphocytes),” the authors noted.