It is predicted that by 2030, there will be approximately 23.6 million new cases of breast cancer per year worldwide. Early detection in cancer cases can play a key role in the success rates of treatment through different breast cancer drugs. Research has discovered that patients who test positive for hormone receptors (HR+) and negative for HER2 receptors (HER2-) have a common form of early detected and easily treated breast cancer. Those in later stages were presented with fewer different breast cancer drugs as options and therefore, lower success rates.
This was the common truth to cancer treatments until the discovery of CDK4/6 inhibitors. These inhibitors worked to target key proteins in the cellular division cycle – a process that cancer thrives from, through dysfunctional cellular division and replication, which feeds tumour growth. Upon discovery, the CDK4/6 inhibitors were fast-tracked for approval by the U.S. Food and Drug Administration because of their effectiveness in blocking tumour growth and disease progression. Used primarily to treat advanced HR+ and HER2- breast cancer cases, three different breast cancer drugs were approved and marketed. They all had the same biological targets and could be used interchangeably throughout cases. Dramatic improvements were soon seen through reduced tumour growth and toxicity, and increased survival periods.
Eventually, two of the three drugs (pablociclib and ribociclib) were met with breast cancer cells that had developed a resistance. The last of the three, abemaciclib, differed as data consistently indicated high rates of cellular death in cancerous cells. As a result, researchers from Harvard Medical School conducted experiments to profile each different breast cancer drug’s cellular growth rate, viability, gene expression, and more in cell lines and animal models.
It was discovered that while all three drugs targeted the same protein inhibitors, abemaciclib had a slight advantage over pablociclib and ribociclib because it also affected the activity of other proteins that contributed to the progression of the cancer. This was seen through artificial cell lines created to be resistant to pablociclib. When tests were conducted, ribociclib had no effect but abemaciclib effectively responded. With potentially fewer toxic effects but more efficacious behaviour, abemaciclib proved to be more advantageous as a treatment for advanced breast cancer.
The implications of these results go beyond the scope of treatment options for breast cancer. The importance of characterizing advertised drugs and their inhibitions or biological effects may be the next step in chronic disease treatment. Despite patients presenting with the same diagnosis, the biological profile of the illness may differ and could be the reason for one drug being more effective than another.
The authors did stress that their results are currently pre-clinical, laboratory-based experiments and should be taken lightly when making clinical decisions between different breast cancer drugs. However, the findings present as a reminder that despite being marketed for the same target, drug classes are not necessarily equally effective in all situations.
Written by Stephanie Tsang
Keyword: different breast cancer drugs
Breast Cancer Worldwide. (2019). Retrieved from https://www.abcglobalalliance.org/articles/breast-cancer-worldwide/.
Hafner, M., Mills, C. E., Subramanian, K., Chen, C., Chung, M., Boswell, S. A., … Sorger, P. K. (2019). Multiomics Profiling Establishes the Polypharmacology of FDA-Approved CDK4/6 Inhibitors and the Potential for Differential Clinical Activity. Cell Chemical Biology, 26(8). doi: 10.1016/j.chembiol.2019.05.005
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