Researchers found that two immune checkpoint inhibitors that target programmed cell death protein 1 (PD-1) and programmed cell death ligand (PD-L1) have shown promising results in treating triple-negative breast cancer. The findings of this study were recently published in Cureus.
Triple-negative breast cancer refers to a subtype of breast cancer in which the tumor does not test positive for estrogen, progesterone receptors or epidermal growth factor 2. This cancer type is more difficult to treat, as it presents doctors with fewer therapeutic options. Furthermore, this cancer tends to spread more quickly, often leading to poorer patient outcomes.
Investigators have hence focused their attention on developing new therapies to treat triple-negative breast cancer. Currently, standard approaches include chemotherapy, immunotherapy and surgery.
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The research team looked into existing studies that included research on therapies that inhibit PD-L1 and PD-1, both of which are known as immune checkpoints. There is already some evidence that immune checkpoint inhibitors may alter the course of triple-negative breast cancer. After combing through available studies on this subject, the research team selected six for analysis.
First, investigators observed that the frequency of side effects of PD-L1 and PD-1 inhibitors were comparable with chemotherapy. There were no increases in immune-mediated adverse effects.
In terms of patient outcomes, individuals treated with anti-PD1 and PD-L1 had a complete response rate (meaning all cancer had disappeared) of 6.79%, compared with 2.37% in the control group. Partial response (meaning a tumor saw significant shrinkage) in the former was 38.08%; in the latter, this was 17.48%. In addition, the use of anti-PD1 and PD-L1 increased the mean duration of response by 2.96 months.
“Immune checkpoint inhibitors have a great deal of promise as a new treatment for [triple-negative breast cancer],” the authors of the study wrote. “We anticipate that this finding will act as a springboard for more research on checkpoint inhibitor immunotherapy, revealing its promise as an efficient and acceptable treatment for breast cancer, particularly [triple-negative breast cancer].”