April 2, 2020

Targeted Therapy: Striking Cancer Cells from Within

By Jared Kobulnicky, MD

 

One of the most promising developments in cancer treatment over the past few years is the rapid emergence of targeted therapy.  

Unlike chemotherapy and immunotherapy, targeted therapy attacks specific mutations in the DNA of cancer cells. The goal is to interfere with growth processes inside those cells – the signals that drive a disease – with fewer side effects than traditional chemotherapy.  

The first versions of targeted therapy appeared in the 1990s and treated chronic myeloid leukemia. Since then, research has led to a growing understanding of different cancer subtypes at the molecular level, allowing for the development of more precise treatment options.  

There are now dozens of approved targeted therapy medications, with many more promising drugs in clinical trials or in the early stages of development. Physicians have seen particularly positive results in the treatment of advanced melanoma and lung cancer, and we are expanding uses to other more commonly seen diseases such as breast, colon and prostate cancer. 

Each medication targets precise structural alterations in the DNA of cancerous cells or tissues that fuel a tumor’s growth, such as surrounding blood vessels, without harming any healthy cells. Therefore, these medications impact only malignant cells by blocking gene signals that instruct them to divide rapidly or stay alive longer than normal cells. 

While side effects vary by patient and disease type, they tend to be less disruptive and more predictable than those experienced with chemotherapy. 

Next-Generation DNA Sequencing is the best way to pinpoint candidates eligible for targeted therapy. Testing from blood or tumor samples reliably maps chemical building blocks and mutations within cancerous cells to determine if there is an approved medication for that particular anomaly. 

For example, about half of advanced melanomas have a mutation in the BRAF gene, which alters a protein involved in cell growth and leads to uncontrolled division. Inhibitors that interfere with an enzyme responsible for protein activation have proven highly effective in hindering cell division.  

Targeted therapies typically involve taking pills at-home at least once daily, a much more convenient option for patients than in-office infusions. For now, these drugs tend to be employed as standalone treatments to avoid potentially harmful side effects. However, ongoing research may discover we can combine them with other treatments for even better results. 

Currently, physicians are prescribing targeted therapy for patients with advanced diseases that have metastasized or recurred after previous treatments. However, oncologists are increasingly using the medications for treating earlier-stage diseases.

At VOA, we have seen positive results in patients with melanoma, lung cancer, breast cancer, leukemias and lymphomas, as well as other tumor types.

Patients should understand that chemotherapy, radiation and immunotherapy can all be highly effective treatment options, depending on cancer type and stage, and will continue to play crucial roles in disease management. 

Still, the future looks bright for targeted therapy, as individualized cancer care steadily progresses into more of a treatment norm than an exception. This should inspire great optimism in patients and physicians alike.  

Dr. Kobulnicky is a medical oncologist and hematologist with Virginia Oncology Associates, based primarily in Hampton and Newport News. Virginiacancer.com