FDA Approves First Biosimilar for Breast Cancer Treatment
In December 2017, the U.S. Food and Drug Administration approved the biosimilar trastuzumab-dkst (Ogivri) for treatment of HER2-positive breast cancer of any stage. It is a biosimilar of trastuzumab (Herceptin), the standard treatment for this type of breast cancer.
In the U.S. trastuzumab-dkst is the first biosimilar to be approved for breast cancer, and only the second biosimilar to be approved for any cancer. The FDA also approved it for treatment of HER2-positive metastatic stomach cancer.
What Are Biosimilars?
The active ingredients in most medicines are chemicals. It’s possible for different companies to make their own version of brand-name medicines using the same chemicals. These exact copies of the brand-name medicines are called generics.
But some medicines, like trastuzumab, are made in living cells. They are called “biological drugs,” or biologics. Because they are made in living cells, which can naturally be slightly different from each other, biologics can’t be copied exactly, the way chemical medicines can be. So instead of companies copying biologics to produce and sell their own generic version, they have to make new biologic medicines that are highly similar to and act the same as the original brand-name version. These are called biosimilars. For a biosimilar to receive FDA approval there must be no significant difference in how safe and effective the biosimilar is compared to the original biologic medicine.
About Trastuzumab and Trastuzumab-dkst
HER2-positive breast cancer develops when cells have too many copies of a gene called HER2. This causes the cells to make too many copies of HER2 proteins that can pile up on the surface of cells and cause cancers to grow out of control. About 20 percent of breast cancers are HER2-positive.
Trastuzumab is a targeted therapy that can prevent early-stage HER2-positive breast cancer from becoming metastatic, or keep HER2-positive metastatic breast cancer from growing and spreading. The FDA approved it in 1998. It is the most common treatment for HER2-positive breast cancer, and is usually paired with chemotherapy.
Trastuzumab is made by the pharmaceutical company Genentech and sold under the brand name Herceptin. The biosimilar version, trastuzumab-dkst, was jointly created by the pharmaceutical companies Mylan and Biocon and will be sold in the U.S. by Mylan under the brand name Ogivri.
Though the FDA approved the biosimilar, Mylan won’t be able to sell it in the U.S. until 2019. Genentech holds a patent for trastuzumab, which gives them the right to be the only seller of the medicine for a period of time. The patent expires in 2019. It is not yet known what the price of trastuzumab-dkst will be, but it is expected to be lower than trastuzumab, which can cost more than $60,000 a year.
Trastuzumab and trastuzumab-dkst are both given intravenously, meaning by vein. They have the same potential side effects, including headache, diarrhea, nausea, chills, fever, infection, difficulty sleeping, cough and rash. Both medicines pose a rare but serious risk of heart problems that can usually be resolved by stopping the medicine or taking heart medicine.
What This Means for You
Trastuzumab-dkst will not be available until at least 2019. So if you currently take trastuzumab, you should continue to do so until your doctor recommends you stop.
Other companies are also making trastuzumab biosimilars that will likely be FDA approved in the next few years. More companies making a medicine usually means lower costs for the people who need it. For example, generic medicines can cost much less than brand-name medicines. Biosimilars will treat HER2-positive breast cancer as well as the original biologic, but potentially at a lower price. In Europe, biosimilars have been approved since 2006. This has helped save people money and allowed more people to get access to these medicines.
Because they’re made in living cells, all biosimilars and the original products they’re similar to have differences. These differences are carefully monitored by the FDA to ensure biosimilars are as safe and work as well as the original medicine. Still, because biosimilars are a new class of medicines, your doctor may prefer to recommend trastuzumab, or you might feel more confident taking trastuzumab. Talk to your doctor if you’re interested in learning more about trastuzumab-dkst and about any concerns you may have
It’s important to know that how your doctor prescribes your treatment for HER2-positive breast cancer will matter when you go to the pharmacy. Many people ask their pharmacist for generic versions of prescribed medicines to save money. But you likely won’t be able to ask your pharmacist for trastuzumab-dkst if your doctor prescribes trastuzumab. In most states pharmacists can’t give you a biosimilar if your doctor prescribed the original biologic, unless the FDA considers the biosimilar and the original biologic to be so highly similar that they are “interchangeable.”
To be considered interchangeable, the biosimilar must not only produce the same result as the original biologic in everyone. There must also be a clinical trial showing that switching between the original biologic and the biosimilar is safe and equally effective. So far, the FDA does not consider any biologics and biosimilars, including trastuzumab and trastuzumab-dkst, interchangeable. LBBC will continue to report on biosimilars as information becomes available. You can also learn more about this new class of medicines at the FDA’s website.