DETROIT, Mich. (WOWO) — The FDA has approved a new daily pill for certain people with advanced breast cancer, with a newly authorized blood test designed to detect treatment resistance before it can be seen on a scan.
Etcamah, also known as camizestrant, is approved for a specific group of patients whose breast cancer has spread beyond the breast, uses estrogen to grow and does not have high levels of the HER2 protein. The treatment is designed for cancers that develop a particular genetic change allowing them to resist estrogen-blocking drugs.
The drug is aimed at a problem that can occur during treatment for hormone-sensitive breast cancer. Some tumors adapt to drugs that block estrogen, allowing cancer cells to continue growing despite treatment.
One mechanism involves a change in the ESR1 gene. That change can allow cancer cells to keep growing even when estrogen is blocked.
Etcamah is designed to target tumors with that resistance and is taken along with one of three existing drugs known as CDK4/6 inhibitors.
What sets the new treatment apart is the role of a blood test called Guardant360 CDx.
The test looks for tiny pieces of tumor DNA circulating in the bloodstream. That can identify an ESR1 change before imaging shows that the cancer is growing.
That earlier warning could give doctors and patients an opportunity to change treatment before the cancer’s progression becomes visible on a scan.
The clinical trial results showed patients who switched to Etcamah went about 16 months before their cancer worsened. Patients who remained on their original treatment went about nine months before their disease progressed.
That amounts to roughly seven additional months before the cancer worsened for patients who switched to Etcamah.
The FDA’s approval was accelerated and was based on evidence that the drug gave patients more time before their cancer worsened, rather than evidence that it extends overall survival.
AstraZeneca, the drug’s manufacturer, is required to conduct additional studies to determine whether the treatment provides a meaningful clinical benefit.
The treatment also carries important safety warnings.
The prescribing information includes a boxed warning about the risk of an irregular heart rhythm. Additional warnings include the potential for an abnormally slow heart rate and the risk of harm to an unborn baby.
The FDA approval applies to a specific population of patients with advanced breast cancer, rather than all people diagnosed with the disease.
The combination of a targeted drug and a blood test that can identify resistance earlier represents a shift toward using tumor DNA in the bloodstream to help determine when treatment needs to change.
For patients whose tumors develop ESR1-related resistance, the new approach could provide an earlier opportunity to move away from a treatment that is no longer controlling the cancer.
