What are NAbs?

NAbs stands for neutralizing antibodies. An antibody is a substance that your body produces when it is exposed to something it doesn't recognize, such as viruses or bacteria. It is designed to help the body get rid of the foreign invader.

Usually, antibodies are useful because they help the body fight off viruses and bacteria. But sometimes, your body can produce antibodies to your MS medication. These antibodies, called neutralizing antibodies, can bind to the medication and make it less effective. Your doctor can tell whether you have NAbs by using a blood test.

NAbs have been reported with the following disease-modifying medications (medications to slow the progression of the disease) for multiple sclerosis (MS):

  • interferon beta-1a once weekly (Avonex®)
  • interferon beta-1b (Betaseron®)
  • glatiramer (Copaxone®)
  • interferon beta-1a three times weekly (Rebif®)

For the interferon medications (see above), evidence suggests that NAbs make the medications less effective. But it is not universally agreed whether NAbs actually decrease the effectiveness of glatiramer. So far there is no convincing evidence to suggest that this is the case.

The risk of developing NAbs is different for each disease-modifying medication. To find out the risks of each medication and whether you may be at risk, read "Am I at risk of developing NAbs?"

All material copyright MediResource Inc. 1996 – 2021. Terms and conditions of use. The contents herein are for informational purposes only. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition. Source: www.medbroadcast.com/healthfeature/gethealthfeature/MS-The-Role-of-NAbs

Am I at risk of developing NAbs?

Neutralizing antibodies (NAbs) can make your MS medication less effective. Could you be at risk of developing NAbs?

There's no way to tell for sure who will develop NAbs to their MS medication. Anyone taking a disease-modifying medication for MS could potentially develop NAbs. But there are a few things that can increase the chances of NAbs:

  • Being on treatment for more than 12-18 months: NAbs usually start to appear after 12-18 months of treatment.
  • Dosage: higher doses may increase the risk of NAbs for some medications.
  • How often the medication is used: More frequent use (for example, three times a week versus once weekly) can increase the risk of NAbs for some medications.

Although the things listed above can increase the risk of NAbs, this does not mean that you should change a treatment that is working for you because you are worried about developing NAbs. Most people never develop NAbs, and of those who do, not all experience a loss of effectiveness in their treatment. Talk to your doctor for further guidance if you are concerned about NAbs.

The medication you're taking can also make a difference. Each of the interferon medications has a different risk of developing NAbs. In studies designed to measure the rates of NAbs in different medication therapies:

  • interferon beta-1a once weekly (Avonex®) had a 2% to 6% risk of NAbs.
  • interferon beta-1a three times weekly (Rebif®) had a 24% to 31% risk of NAbs.
  • interferon beta-1b (Betaseron®) had a 23% to 41% risk of developing NAbs.
  • natalizumab (Tysabri®) had a 4.5% to 14.1% risk of developing Nabs.

These results came from different clinical trials, so they cannot be directly compared. However, studies that only included interferon medications mentioned above have shown that interferon beta-1a once weekly (Avonex®) had the lowest risk of developing NAbs. It's not clear exactly why the risk varies, but it is believed that this may be related to the structure of the medications, the dose, the way the medications are manufactured, the route of injection (under the skin vs. into a muscle), or how often they're used.

All material copyright MediResource Inc. 1996 – 2021. Terms and conditions of use. The contents herein are for informational purposes only. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition. Source: www.medbroadcast.com/healthfeature/gethealthfeature/MS-The-Role-of-NAbs

What do NAbs mean for my MS therapy?

How can NAbs affect your MS therapy? This is an ongoing area of study, and we do not yet have a complete understanding of the effects of NAbs on MS treatment. However, knowledge in this area has come a long way in recent years. Here's what we do know:

NAbs may make your interferon medication less effective. Some people taking interferon medications, such as Avonex® (interferon beta-1a once weekly), Rebif® (interferon beta-1a three times weekly), or Betaseron® (interferon beta-1b), find that NAbs may decrease the effectiveness of their treatment, with effects including:

  • higher relapse rates
  • more active MS as shown on MRI scans
  • higher rates of disease progression

The effects of NAbs sound alarming, but there are a few things to keep in mind:

  • NAbs do not always make your treatment less effective and they are not the only factor that determines whether your treatment will be effective. People with high levels of NAbs that continue over long periods of time are most at risk of decreased treatment effectiveness.
  • NAbs take time to develop, and it can be years before they affect your treatment. NAbs usually appear after 12-18 months of treatment. But one study has found that the NAbs did not start to have a significant effect on treatment effectiveness until about 4 years of treatment.
  • Many people with NAbs find that the NAbs go away on their own over time. NAbs are more likely to go away if you have low NAb levels.

It's important to understand that testing positive for NAbs does not mean that you will need to stop or change your MS treatment. In deciding whether to switch treatment, you and your doctor will need to consider your symptoms and MRI test results to see whether the NAbs are affecting your response to the medication. If your medication is still working well for you, there may be no need for a change. If your medication is not working as well as it once did, and you have tested positive for NAbs more than once, switching to a non-interferon medication such as glatiramer may be an option.

If you are concerned about NAbs, talk to your doctor for more information and guidance.

NAbs are an active area of MS research. Ongoing research should help to answer these and other questions. It will also help us gain a better understanding of why and how NAbs affect MS therapy and what can be done about them.

All material copyright MediResource Inc. 1996 – 2021. Terms and conditions of use. The contents herein are for informational purposes only. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition. Source: www.medbroadcast.com/healthfeature/gethealthfeature/MS-The-Role-of-NAbs

Unanswered questions about NAbs

Knowledge about NAbs has come a long way in recent years, but there are still some unanswered questions about them and what they mean for MS therapy. Areas that require more research include:

  • developing better and more consistent ways of measuring NAbs so that results are consistent between laboratories in different locations
  • learning more about which factors increase the risk of NAbs to help predict who may develop NAbs
  • understanding exactly how NAbs are produced and how they affect MS medications
  • determining the effect of NAbs on the progression of MS in people taking disease-modifying medications (such as interferon beta)
  • understanding why NAbs affect medication response for some, but not all, people
  • determining why NAbs go away in some cases and how this influences the effectiveness of disease-modifying medications
  • finding a way to prevent the development of NAbs, to get rid of NAbs once they appear, or to stop them from affecting MS medications
  • learning how NAbs affect MS therapy over the long term (several years)

NAbs are an active area of MS research. Ongoing research should help to answer these and other questions. It will also help us gain a better understanding of why and how NAbs affect MS therapy and what can be done about them.

All material copyright MediResource Inc. 1996 – 2021. Terms and conditions of use. The contents herein are for informational purposes only. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition. Source: www.medbroadcast.com/healthfeature/gethealthfeature/MS-The-Role-of-NAbs