Nerlynx is used to treat people diagnosed with early-stage, HER2-positive breast cancer for an extended period of time after surgery and a chemotherapy regimen that included Herceptin. Doctors call this extended adjuvant therapy.
Nerlynx was the first medicine to be approved specially for extended adjuvant therapy for early-stage, HER2-positive disease.
Four different tests can be used to figure out if the cancer is HER2-positive and if it will likely respond to Nerlynx:
- IHC (ImmunoHistoChemistry)
IHC is the most commonly used test to see if a tumor has too much of the HER2 receptor protein on the surface of the cancer cells.
The IHC test gives a score of 0 to 3+ that indicates the amount of HER2 receptor protein in tumors. If the tumor scores 0 to 1+, it's called "HER2 negative." If it scores 2+ or 3+, it's called "HER2 positive."
Women with IHC positive scores tend to respond favorably to Nerlynx. The drug is not considered effective for tumors with IHC scores of 0 or 1+.
It's important to note that results on the IHC test may vary from lab to lab, and that some labs are more proficient at HER2 testing than others. Discuss with your doctor whether you might want to get a FISH test, especially if you have a 1+ or 2+ result from IHC. That way you can get another measure of whether the tumor might respond well to Nerlynx .
The IHC test results are most reliable for fresh or frozen tissue samples. IHC tends to be an unreliable way to test tissue that's preserved in wax or other chemicals. FISH testing is the preferred way to assess preserved tissue samples.
The FISH test looks for the HER2 gene abnormality. This test is the most accurate, but less available, way to find out if a breast tumor is likely to respond to Nerlynx
With the FISH test, you get a score of either "positive" or "negative" (some hospitals call a negative test "zero"). If the cancer is FISH positive, it will probably respond well to Nerlynx