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Erelzi™ (etanercept-szzs)

Erelzi is a biosimilar to Enbrel® (etanercept) that is used to treat ankylosing spondylitis (AS). Generally, in patients with AS, biologics are used when symptoms have not been adequately managed with NSAIDs (non-steroidal anti-inflammatory drugs). Erelzi is also approved to treat rheumatoid arthritis and polyarticular juvenile idiopathic arthritis (JIA).1

What is a biosimilar?

Biosimilars are a type of biologic therapy that are highly similar to an already approved biological product. To receive FDA approval, biosimilars must be like their reference product in several key characteristics, including purity, molecular structure, and bioactivity (how it acts in the body). Like biologics, biosimilars have bioengineered proteins that mimic certain functions in human genes or cells, and they are made from living organisms. The sources used to create biological products may be human, animal, bacteria, or yeast.2

What biosimilars are not

Biosimilars should not be confused with generic medications, despite the fact that for both, pathways for regulatory approval are abbreviated as compared to the pathways for approval of new drugs. The chemical structure of a generic small‐molecule drug must be identical to that of its reference product. In contrast, because biologics are proteins produced in living cells, biosimilars usually are not identical to their reference products. to achieve FDA approval, a biosimilar must be highly similar in structure and function, equivalent in efficacy, and comparable in safety and immunogenicity to its reference product, despite potential slight molecular differences between the 2 agents.

What is the ingredient in Erelzi?

The active ingredient in Erelzi is etanercept-szzs, a TNF blocker.1

How does Erelzi work?

AS is a chronic inflammatory arthritis that primarily affects the joints in the spine, although other parts of the body may also be affected. In addition to the joints, many people with AS have inflammation in the locations (entheses) where the ligaments and tendons attach to the bone. This inflammation is called enthesitis and can cause “hot spots” of tenderness along the spine or along the back of the heel.3

TNF is a naturally occurring protein, called a cytokine, that is involved in the normal inflammatory response in the body. In people with AS, there is an excess or abnormal inflammatory response and elevated levels of TNF. Erelzi is a TNF inhibitor. Blocking TNF can help reduce the inflammation and help relieve the symptoms of AS.1

What are the possible side effects of Erelzi?

The most common side effects experienced by people taking Erelzi include infections, headache, and injection site reactions. Because TNF is involved in the normal immune response of inflammation, taking a TNF blocker like Erelzi can make it harder to fight certain infections. Injection site reactions may include redness, itching, pain, or swelling at the site where Erelzi is administered.1

Serious side effects may occur with Erelzi. Some people have had serious infections while taking Erelzi, including tuberculosis (TB), bacterial sepsis, viral, and invasive fungal infections. These serious infections may lead to hospitalization or death.1

Some people have experienced severe allergic reactions to Erelzi.1 People experiencing allergic reactions, including difficulty breathing, swollen face, or rash, should seek immediate medical care.

Erelzi may reactivate the hepatitis B virus in someone who has previously had hepatitis B virus infection.1

There have been some cases of cancer in children and teenagers taking TNF inhibitors like Erelzi. These cancers may lead to death. Children, teenagers, and adults taking Erelzi may have an increased risk of developing lymphoma, melanoma and other skin cancers, or other cancers.1

This is not an exhaustive list of all potential side effects of Erelzi. For more information, patients should talk to their doctor about what to expect. Any new or worsening side effects should be reported to a doctor or healthcare professional.

Things to know about Erelzi

Before beginning treatment with Erelzi, patients should talk to their doctors about all medications (over-the-counter and prescription), vitamins, and supplements they are taking. Some medications or supplements may increase the risk of side effects if taken in combination with Erelzi.1

Before starting treatment with Erelzi, patients should talk to their doctors about all their medical conditions, especially if they1:

  • Have any signs of infection or are prone to frequent infections
  • Have any open sores or cuts on the body
  • Have psoriasis
  • Have HIV, diabetes, or a weakened immune system
  • Tested positive for TB or have been in close contact with someone who has TB
  • Were born in, lived in, or traveled to countries where there is an increased risk of TB (ask your doctor if you aren’t sure)
  • Live in areas of the US where known for fungal infections, including the Ohio and Mississippi Valley and the Southwest
  • Have any nervous system problems like seizures, multiple sclerosis, or Guillain-Barré syndrome
  • Have or have had heart failure
  • Have or have had hepatitis B
  • Are allergic to rubber or latex
  • Are scheduled to have surgery
  • Are scheduled to receive a vaccine
  • Are pregnant or plan to become pregnant or are breastfeeding

Patients should be tested for TB before beginning treatment with Erelzi.1

If an infection occurs while taking Erelzi, patients should contact their doctor. If the infection becomes serious, treatment with Erelzi may be stopped.1

Patients taking this medication should not receive live vaccines.1

During treatment with Erelzi, patients should be monitored for any possible heart problems, anemia, infection, and nerve damage.1

Dosing information

Erelzi is given as an injection under the skin (subcutaneously). It comes in a prefilled syringe or a prefilled pen that is given once weekly.1 Patients should talk to their doctor about any questions on their dosing regimen.

Written by: Emily Downward | Last reviewed: February 2019
  1. Erelzi prescribing information. Available at https://www.erelzi.com/globalassets/erelzi2/erelzi-label-jan-2018.pdf. Revised 1/2018. Accessed 1/9/19.
  2. What is a biosimilar? Food and Drug Administration. Available at https://www.fda.gov/downloads/Drugs/DevelopmentApprovalProcess/HowDrugsareDevelopedandApproved/ApprovalApplications/TherapeuticBiologicApplications/Biosimilars/UCM585738.pdf. Accessed 1/9/19.
  3. Ankylosing spondylitis. Mayo Clinic. Available at https://www.mayoclinic.org/diseases-conditions/ankylosing-spondylitis/symptoms-causes/syc-20354808. Accessed 1/8/19.