New FDA Approval: Amjevita
Amjevita is a biosimilar to adalimumab [Humira], so it has the same indications. It's used in inflammatory conditions mediated by the immune system. We're talking things like the following:
- Crohn's Disease
- Ulcerative colitis
- Rheumatoid arthritis
- Ankylosing spondylitis (whatever the hell that is)
- Plaque psoriasis
- And, notably, it's indicated for polyarticular juvenile idiopathic arthritis for ages 4 years and older
You'll remember seeing our discussion about this in a previous post on the biosimilar for infliximab.
Basically, to help differentiate biosimilars from their 'brand' counterparts, the FDA has mandated that biosimilar product names are followed by a random string of 4 letters with no meaning.
The approval process for biosimilars is very different than the process for regular generic drugs.
The "bio" part means that the manufacturing process involves living organisms. For example, we could use bacteria like E. coli as a sort of "factory" to make many copies of our monoclonal antibody.
Biosimilars can be though of as "generic" versions of the brand drug. But there's a few sticking points. With biologic drugs, the process itself is patented. So what that means is that a biosimilar has to make the same monoclonal antibody as the brand....but it has to do it using a different process.
And these processes can be very sensitive to changes. The wikipedia page for biosimilars has a great analogy, where they compare biosimilars to different types of wine. A malbec is made with different grapes and different yeast than a chardonnay. And although it's a similar overall 'process' to make each type of wine, the end result using different ingredients are very different from each other.
You can just say "they're both wine" and move on with it. And this is especially true in medicine using monoclonal antibodies. Small changes in the process can lead to very different end products. This is why you're seeing the relatively slow pace of biosimilar approvals in the US (as of this writing, there are only 4). It takes a lot of work and testing to ensure safety and efficacy.
But rest assured, you will see more biosimilars as the patents continue to run out on the original products. And it's kind of a big deal, because the original products are cripplingly expensive.
How it Works
Amjevita is a fully human monoclonal antibody against Tumor Necrosis Factor alpha (TNF-a). I've previously explained what "fully human monoclonal antibody" means with a post I wrote for Pharmacy Times.
As far as what TNF-a actually dose....it's a part of your immune system that basically goes around the body acting like a signal flare. It causes the production of inflammatory cytokines and interleukins. It sings a siren song that causes immune cells like WBCs to flock to it and activate.
Basically, it's like one of those inflatable dancing stick men that car dealerships use to get your attention.
Inflammatory autoimmune disorders like Crohn's and rheumatoid arthritis have been found to show TNF-a levels that are elevated. By making an antibody that targets TNF-a, we can alleviate the symptoms of those diseases.
Notable Adverse Effects
Unfortunately, TNF-a serves a critical role as part of a healthy immune response. So inhibiting it can lead to some problems. For example:
- Black Box Warning for serious infections (TB, invasive fungal infections like aspergillosis, and opportunistic microbes like Listeria)
- Black Box Warning for lymphoma and other malignancies
- Increased LFTs
- Respiratory issues (infection, cough, pharyngitis)
And remember, monoclonal antibodies are foreign proteins that are often made using bacteria like E. coli....there's a considerably high risk of infusion reactions.
Current Place in Therapy
Adalimumab (whether Humira or Amjevita) is not a first line treatment for anything. It's usually reserved for moderate to severe cases that haven't responded to first line therapies. Because Amjevita was approved for all of the Humira indications, it can be used any time Humira is indicated.
Please note, that biosimilars are not interchangeable. They are not generics that can be substituted. They are entirely different products.
That being said, although the cost is high (even for the biosimilar), and there are nasty risks associated with biologic use, appropriate use of TNF-a inhibitors can lead to wonderful results in some patients. Crohn's disease can go from a seriously debilitating condition to something more manageable.
Biosimilars like Amjevita are paving the way for competition in biologic drugs. Which will help bring the cost down for everyone. Be on the lookout for more, because they will be coming.