Pabrolizumab (Pembrolizumab) is an immunotherapy drug that in 2014 became the first PD-1/PD-L1 inhibitor approved for marketing by the U.S. Food and Drug Administration (FDA) for the treatment of melanoma, lung cancer, gastric cancer, cervical cancer, and many other cancers.
Pabrolizumab is currently available in China with an approved indication for unresectable or metastatic melanoma. Although there is no strong evidence that the drug can be used directly in breast cancer, pablizumab is indicated abroad for patients with unresectable or metastatic cancers with high microsatellite instability (MSI-H) or defective mismatch repair (dMMR), which includes breast cancer.
For breast cancer, research in immunotherapy has focused on triple-negative patients, and studies are still being explored.
What is the role in breast cancer?
Pabrolizumab restores the anti-tumor activity of T cells by binding to the T cell surface PD-1 (i.e., programmed cell death protein-1) receptor in the immune system, blocking the binding of PD-1 to the ligand PD-L1 on the surface of tumor cells and thus exert anti-tumor effects.
One study showed that the overall effectiveness of pablizumab treatment in patients with hormone receptor-positive advanced breast cancer was only 12%.
Another study included 111 cases of metastatic triple-negative breast cancer, 32 of whom had positive tumor tissue PD-L1 expression and were given pabolizumab monotherapy, and these patients had a progression-free survival rate of 24.5% at month 6 of treatment, with mild treatment-related adverse effects.
27 patients were evaluated for efficacy, and the objective remission rate was less than 20%. This suggests that further efficacy potential needs to be explored for pablizumab in the treatment of metastatic triple-negative breast cancer.
Summary
The immunotherapy drug pablizumab has been approved abroad for the treatment of many advanced cancers, but in breast cancer it is in clinical trials for now, and it is critical to improve the efficiency of treatment.
It is believed that as research progresses, breast cancer patients are also expected to have better survival from immunotherapy in the future.