Enbrel (etanercept)

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Etanercept (Enbrel) is a TNF-receptor fusion protein manufactured in collaboration by Amgen and Pfizer and indicated for the treatment of RA, as well as other autoimmune conditions, including plaque psoriasis, ankylosing spondylitis, psoriatic arthritis, and polyarticular juvenile idiopathic arthritis.

 

Etanercept (Enbrel): overview and efficacy

Etanercept (Enbrel) is a TNF-receptor fusion protein manufactured in collaboration by Amgen and Pfizer and indicated (approved for use) for the treatment of RA, as well as other autoimmune conditions, including plaque psoriasis, ankylosing spondylitis, psoriatic arthritis, and polyarticular juvenile idiopathic arthritis.1

 

How does Enbrel work?

Enbrel is a TNF-receptor fusion protein that binds to both TNF-α and TNF-β, preventing them from interacting with their receptors and thereby inhibiting their function in the immune response.

 

How is Enbrel taken?

Enbrel is taken as a subcutaneous (under the skin) injection of 25 mg twice a week or 50 mg once a week.

If you are administering Enbrel to yourself, make sure you have been fully instructed on how to measure and administer the correct dose. See the “Instructions for Use” booklet that comes with Enbrel. If you have any questions about how to prepare and administer Enbrel, call your doctor or the Enbrel patient support number 1-888-436-2735.1

 

Are there people who should not take Enbrel?

Enbrel should not be taken by a person with sepsis (a condition in which harmful bacteria or other toxins are present in tissues, usually due to an infected wound).1

With Enbrel, there is an increased risk for serious infections. This is because Enbrel can decrease the ability of the immune system to fight infections. Enbrel should not be started if you have an infection. If an infection develops while you are taking Enbrel, contact your doctor immediately.1

If you have a severe allergic reaction while taking Enbrel, contact your doctor immediately.1

Enbrel is a pregnancy category B drug. Animal studies found no evidence that Enbrel poses harm to the fetus. However, there have been no well-controlled studies in pregnant women. Therefore, Enbrel should be used during pregnancy only if it is clearly needed.1

It is not known whether Enbrel is excreted into human milk. Because of the risk of adverse effects, women who are taking Enbrel should either not breastfeed their children or discontinue the drug.1

 

What is the evidence that Enbrel works in RA?

The effectiveness of Enbrel in RA was evaluated in four randomized, controlled trials conducted in patients with active RA. One study compared Enbrel (10 or 25 mg twice weekly) alone with placebo in 234 patients who had failed to respond adequately to a range of disease-modifying anti-rheumatic drugs (DMARDs). Two studies compared Enbrel (10-25 mg twice weekly) plus methotrexate with placebo plus methotrexate, one in 632 patients with no prior methotrexate treatment experience and the other in 89 patients who had failed to respond adequately to a range of DMARDs, but who were currently on a stable dose of methotrexate. Finally, one study compared Enbrel alone with the combination of Enbrel (25 mg twice weekly) plus methotrexate in 682 patients who had an inadequate response to at least one DMARD other than methotrexate.1

Disease control and clinical response. Enbrel alone and in combination with methotrexate resulted in consistently higher rates of ACR20, 50, and 70 response, as well as major clinical responses (defined as a continuous ACR70 response lasting at least 6 months) compared with placebo alone and in combination with methotrexate. Rates of ACR20 response across three studies for Enbrel alone and in combination with methotrexate ranged from 62% to 66% compared with 33% to 56% for methotrexate (alone or in combination with placebo) and 23% for placebo. ACR responses with Enbrel have been shown to be durable, lasting over 60 months in open-label extensions of controlled trials.1

 

Rates of ACR responses from three clinical trials of Enbrel1

Enbrel alone vs placebo

Enbrel + MTX vs placebo + MTX

Enbrel vs MTX

Response Enbrel 25 mg twice weekly (N=78) Placebo (N=80) Enbrel 25 mg twice weekly + MTX (N=59) Placebo + MTX (N=30) Enbrel 25 mg twice weekly (N=207)
ACR20
3 months 62%* 23% 66%* 33% 62%
6 months 53%* 13% 71%* 27% 65%
12 months 72%
ACR50
3 months 41%* 8% 42%* 0% 29%
6 months 40%* 5% 39%* 3% 40%
12 months 49%
ACR70
3 months 15%* 4% 15%* 0% 13%**
6 months 15%* 1% 15%* 0% 21%**
12 months 25%
*Statistical significance: P<0.01 vs placebo or placebo + methotrexate (MTX).
**Statisical significance: P<0.05 vs MTX.

 

Radiographic progression. In a large study conducted in 632 patients with no prior methotrexate treatment experience, Enbrel (10-25 mg twice weekly) plus methotrexate resulted in a comparable change from baseline in Total Sharp Score (TSS) and joint space narrowing score at 12 months versus placebo plus methotrexate. Enbrel resulted in significantly less joint erosion at 6 months, maintained through 12 months, compared with placebo plus methotrexate.1

 

Radiographic changes from baseline in study of Enbrel + methotexate (MTX) versus placebo + MTX

Enbrel 25 mg twice weekly + MTX Placebo + MTX
Modified Total Sharp Score
6 months 0.57* 1.06
12 months 1.00 1.59
Erosion score
6 months 0.30** 0.68
12 months 0.47** 1.03
Joint space narrowing score
6 months 0.27 0.38
12 months 0.52 0.56
*Statistical significance: P=0.001 vs placebo + MTX.
**Statisical significance: P=0.002 vs placebo + MTX.

 

Is there a generic form of Enbrel?

There is no generic equivalent to Enbrel.

view references
1. Enbrel (etanercept) Prescribing Information. Amgen and Pfizer; Thousand Oaks, CA: 2013.further reading
Etanercept injection. Available at: http://www.nlm.nih.gov/medlineplus/druginfo/meds/a602013.html. Accessed on 051513. Fox B, Taylor N, Yazdany J. Arthritis for Dummies. Hoboken, NJ: Wiley Publishing, Inc; 2004.
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