Despite the complexity of cancer, we have traditionally treated patients with the same cancer diagnosis in the same way with variations based on stage and grade. For example, advanced epithelial ovarian cancer is often treated with Carboplatin and Taxol® as a front line therapy following a debulking surgery. However, cancer is like a fingerprint and is very unique to each individual.

Cancer is a disease characterized by uncontrolled growth and spread of abnormal cells. Mutations in genes involved in growth and replication are key to the development of cancer. For cancer to develop, DNA cell mutations must occur in a number of genes that regulate normal cell processes, such as growth and death. In addition, these mutations tend to multiply over time as the cells proliferate, making the tumors more complex and heterogeneous. Additionally, cancer cells by definition are more actively engaged in replication than non-cancerous cells which adds to the complexity of cancer.

New advances have given scientists greater options for cancer treatments. One of those options is targeted treatments, a new form of cancer therapy. They take advantage of the biologic differences between cancer cells and healthy cells by "targeting" faulty genes or proteins that contribute to the growth and development of cancer. Many times these drugs are combined with chemotherapy and biologic therapy. Therefore, targeted therapy allows patients to receive very different treatments, who seemingly have the same type, stage and grade of cancer.

In order for cells to grow, divide, or die, they send and receive chemical messages. These messages are transmitted along specific pathways that involve various genes and proteins in a cell. Targeted treatments fight cancer by correcting or modifying defective pathways in a cancer cell. In healthy cells, each pathway is tightly controlled. For instance, healthy cells are allowed to divide into new cells, and damaged cells are destroyed. However, in cancerous cells, certain points in the pathway become disrupted, usually through a genetic mutation.

It is important for you to learn more about targeted therapies and biological treatments. It is rapidly changing and keeping current will be critical. Targeted therapies are changing the landscape of cancer therapy and are key to treatments for today and tomorrow.

The Hallmarks of Cancer as Targets for Therapy

Key to targeted therapy is a solid understanding of cancer and its mechanisms. The following have been identified as six hallmarks of cancer:

Escape control from growth factor signals
One hallmark of cancer cells is their ability to escape control of extracellular growth factor signals. Either due to overactivity or mutuations in growth factor receptors, signal transduction components or transcription factors, cancer cells essentially generate their own growth signals and therefore, can grow independently. Today, monoclonal antibodies that target aberrant growth factor signals or receptors are examples of targeted cancer therapies.

Loss of tumor suppressor function
Tumor suppressor genes typically activate the “don’t grow” signals between cells. The loss of this tumor suppressor function in cancer cells can lead to unopposed activation of a growth stimulating transcription factor. This factor is a promising target for attack by small molecule drugs under development.

Disruption of cell death
Cancer disrupts the normal process of programmed cell death [apoptosis]. Surplus cells receive extracellular signals to kill themselves and pre-cancerous cells can detect that they are abnormal and commit suicide. Disruption of this process through mutuations in tumor suppressor genes, for example allows the cancer cells to survive and proliferate.

Chromosome tips become too short
Normally, the tips of the chromosomes become progressively shorter in each cycle of cell proliferation [with the exception of stem cells]. After 60-70 doublings, the chromosome tips become to short to support additional cell division without compromising chromosome integrity and either cease to multiply or die. Cancer cells have an enzyme that maintains DNA sequences and have limitless replicative potential. One strategy of cancer therapy is to develop inhibitors of the enzyme.

Ability to capture new blood vessel formation
By creating new blood vessel formation, cancer cells supply themselves with oxygen and nutrients. Cutting off blood supply to tumors [anti-angiogenesis] is a promising cancer therapy.

Metastasis
Cancer cells have the ability to leave the primary tumor and invade distant tissues. This process involves severing linkages between cells and their intracellualar matrix. The activation of extracellular protease enzymes allows migrating cancer cells to slip through spaces cells in tissues and blood vessel walls. This process is not well understood and developing targeted therapies has been slow.