Our cells are a complex network of various unique proteins, each with its own role to play. These proteins, whether expressed on the cell's inside (intracellular) or outside (surface), control fundamental biological processes like growth, division, and even death. Cancer cells also express these proteins, which can play a crucial role in their growth and survival. The development of novel cancer therapies hinges on our deep understanding of how these proteins function and what they control.
Developing drugs and treatments that “target” a specific protein has become an important component of personalized medicine. These types of treatment interventions, known as “targeted therapies,” can work through a variety of mechanisms, but all require an extensive knowledge of how the intended target protein works on a cellular level.
Most targeted therapies fall into one of two categories: small-molecule drugs or monoclonal antibodies. Small-molecule drugs, as their name suggests, are small and can quickly penetrate cancer cells to interact with their intracellular target proteins. Monoclonal antibodies, on the other hand, are synthetic proteins that attach to surface protein targets to alter the biological processes they control.
Oncologists can treat many different types of cancer with targeted therapies. In some cases, a patient will require comprehensive screening, a process that involves analyzing the genetic makeup of the tumor to determine which targets their tumor expresses. For example, a subset of breast cancer patients expresses a protein called HER2, which sends instructions to cells to tell them to grow. A targeted therapy called trastuzumab, a monoclonal antibody, binds the HER2 protein on breast cancer cells, preventing the transmission of these growth signals.
Targeted therapies impact cancer cells through a fascinating array of different mechanisms. Some targeted therapies represent immunotherapies, which target proteins that can boost the immune system. Other target therapies may bind targets that can directly interfere with biological signals involved in tumor growth and metastasis. Another class of target therapies, known as angiogenesis inhibitors, interfere with signaling that regulates the growth of blood vessels needed to supply the tumor with nutrients.
Sources: BMC Med, Cancer Treat Res