Companion Diagnostics Target Therapy to the Patients Most Likely to Respond
What cancer patient would want to use trial and error with various chemotherapies when he or she could know first from a diagnostic that one agent in particular would result in the most successful outcome?
A new field has emerged, companion diagnostics, to help predict a patient’s compatibility with chemotherapy or other cancer treatments. This is a game changer to help ensure drugs are given only to the patients most likely to respond to them.
According to the Food and Drug Administration (FDA), companion diagnostics already play an important role in determining which therapies are the safest and most effective for a particular patient. By identifying treatments that work best for specific patients, less money is spent on those that do not work because patients no longer have to endure multiple treatments to find the one that is right for their case. Companion diagnostics, usually created in combination with targeted therapy, not only reduce cost and waste, but also reduce side effects for the patient.
Over the past several years, the FDA has approved the following five companion diagnostics:
- Zelboraf and the Cobas Test: The drug Zelboraf specifically treats the melanoma of patients whose tumors express a gene mutation called BRAF V600E. Alberto Gutierrez, Ph.D., Director of the Office of In Vitro Diagnostic Device Evaluation and Safety in the FDA’s Center for Devices and Radiological Health, said that approval “is a great example of how companion diagnostics can be developed and used to ensure patients are exposed to highly effective, more personalized therapies in a safe manner.”
- Vysis ALK Break Apart FISH Probe Kit: Developed along with the targeted therapy drug Xalkori for patients with late stage, non-small lung cancer who express the abnormal anaplatic lymphoma kinase gene. The test determines if a patient possesses that gene to ensure that the correct treatment is applied.
- therascreen KRAS RGQ PCR Kit: For those with colorectal cancer who are determining whether the drug Erbitux is right for them. This provides information about the KRAS gene mutation in patients whose colorectal cancer has spread to other parts of the body. If the test shows that the patient does not have the gene mutation, this demonstrates that Erbitux is the correct choice, but not the right one for those with the gene mutation.
- EGFR Mutation Test: Administered in conjunction with the targeted therapy drug Tarceva, which detects the epidermal growth factor receptor gene mutation in patients with lung cancer. If the patient has the genetic mutation that Tarveca targets, then they are “candidates for receiving Tarceva as first line therapy,” Dr. Gutierrez says. Because this gene is present in approximately 10 percent of patients who have non-small lung cancer, it would go far to help improve the treatment and success rate among these patients.
- THxID BRAF: Approved alongside two drugs (Tafinlar and Mekinist) – which treat the most dangerous type of skin cancer – this detects the BRAF V600E or V600K gene mutations associated with the disease. If the tumor of the patient contains either of these genes, both drugs are effective.
Have you – or someone you know – ever been treated with one or more companion diagnostics? What was the experience like and would you recommend it for someone else?