What are targeted therapies?
A targeted therapy is a drug that blocks the growth of cancer by interfering with specific molecules involved in tumour growth. This is different to non-specific treatments like chemotherapy that simply aim to kill rapidly dividing cells.
This new generation of drugs has resulted in a big improvement in melanoma treatment for patients with the spread of the disease to other organs.
Researchers have identified some of the key genetic mutations that drive the growth of melanoma in patients. These discoveries are opening new avenues for treatment options using drugs that selectively block activity of these driving mutations, known as ‘targeted therapy’.
The genetic mutations involved in melanoma development that have been discovered so far have interesting names. They include:
- BRAF (“BEE-raff”)
- NRAS (“EN-rass")
- C-KIT (“SEE-kit”)
More mutations are continuing to be discovered.
How do they work?
Messages are sent inside the cell by a series of molecules that tell the cell how to grow and divide. This process is called a ‘signalling pathway.’
Mutations, or abnormalities, in these signalling pathways can cause cells to rapidly divide and replicate out of control, resulting in tumour formation. The mutated signalling pathways in melanoma cells are the targets for therapy.
Not all melanomas have the same driving mutations. By identifying which molecules are mutated in different forms of the disease patients can be categorised and treated based on their specific mutation. Identifying all of these molecular mutations is what molecular oncology researchers around the world are working on.
Targeted therapies currently available
Currently, there are three targeted therapy regimens that are approved for use in Australia in patients with a BRAF mutation. These regimens combine a drug that targets the BRAF gene mutation (BRAF inhibitor) with a drug that blocks the MEK gene (MEK inhibitor).
The combination of a BRAF inhibitor and a MEK inhibitor has been found to be more effective for shrinking melanoma tumours than using either type of drug on its own.
The combinations are:
- a BRAF inhibitor called dabrafenib and a MEK inhibitor called trametinib
- a BRAF inhibitor called vemurafenib and a MEK inhibitor called cobimetinib
- a BRAF inhibitor called encorafenib and a MEK inhibitor called binimetinib.
There are currently no therapies approved specifically to treat NRAS-mutant or cKIT-mutant melanomas, although some are being tested in clinical trials.
Who are they for?
Not every patient has mutations in their melanoma that are affected by the drugs that are currently available or in trial. Part of treatment at Melanoma Institute Australia includes being tested for these mutations and pairing you with the best option for your situation.
Some of the drugs are still under investigation in clinical trial testing. That means that even though you might have the mutation that correlates to a drug, the trial’s inclusion criteria could still prevent you from qualifying. Take a look at the Clinical Trials section of this site to learn more about how trials work.
The most common side effects seen with targeted therapies include fever, rash, diarrhoea and liver problems, such as hepatitis or elevated liver enzymes.