What are the benefits of TYSABRI for Multiple Sclerosis and Crohn's Disease?

October 10, 2025 •

4 min read

Clinical trials for multiple sclerosis (MS) showed that TYSABRI reduced the number of relapses by 67% compared to placebo over two years. The question is, what are the benefits of TYSABRI and how does this powerful monoclonal antibody help patients with MS and Crohn's disease?

Quick Summary

TYSABRI is a monoclonal antibody that helps manage relapsing multiple sclerosis (MS) by significantly reducing relapses, slowing disability progression, and limiting brain lesions. It is also effective for treating moderate-to-severe active Crohn's disease in adults who have not responded to other therapies by inducing and maintaining clinical response and remission.

Key Points

Significant Relapse Reduction: TYSABRI dramatically reduces the annual relapse rate in relapsing forms of multiple sclerosis (MS).
Slowed Disability Progression: For adults with MS, TYSABRI can slow the long-term accumulation of physical disability.
Decreased Inflammatory Lesions: The medication significantly reduces the development of new and active brain lesions seen on MRI scans for MS patients.
Clinical Remission in Crohn's: TYSABRI can induce and maintain clinical remission in patients with moderate-to-severe active Crohn's disease.
Targeted Action: The drug works by blocking specific immune cells from entering inflamed areas, limiting damage and inflammation in both MS and Crohn's.
Considered a Highly Effective Therapy: TYSABRI is considered a highly effective treatment option, particularly for patients with aggressive disease activity or those who have failed other therapies.
Requires Strict Monitoring: Due to the risk of a serious brain infection called PML, TYSABRI is only available through a restricted program (TOUCH) that includes regular patient monitoring.

TYSABRI, a brand name for the drug natalizumab, is a powerful disease-modifying therapy used to treat certain autoimmune conditions in adults. It is administered as a monthly intravenous infusion in a certified infusion center. By understanding how this medication works and the specific clinical benefits it offers for each condition, patients can have informed discussions with their healthcare providers. The core mechanism involves inhibiting the migration of inflammatory immune cells, known as leukocytes, into the central nervous system or the gastrointestinal tract. This targeted action helps to reduce the inflammation and damage that drives these chronic diseases.

The Benefits of TYSABRI for Multiple Sclerosis (MS)

For adults with relapsing forms of MS, TYSABRI offers multiple significant benefits backed by robust clinical data. These forms include clinically isolated syndrome (CIS), relapsing-remitting MS (RRMS), and active secondary-progressive MS (SPMS). The drug's targeted mechanism focuses on preventing the harmful immune cells from crossing the blood-brain barrier, which is a key process in MS pathology.

Relapse Rate Reduction

One of the most notable benefits is the dramatic reduction in the frequency of relapses. A pivotal two-year trial, the AFFIRM study, showed that TYSABRI resulted in a 67% relative reduction in the annualized relapse rate compared to placebo. A high percentage of patients receiving TYSABRI were also relapse-free at the two-year mark. For individuals with highly active MS, this reduction is particularly pronounced.

Slowed Disability Progression

Clinical trials have also demonstrated TYSABRI's ability to slow the accumulation of disability over time. In the AFFIRM trial, patients on TYSABRI had a 42% relative risk reduction of experiencing sustained disability progression compared to those on placebo. While MS cannot be cured, delaying the build-up of disability is a critical goal of treatment.

Limited Lesion Development

TYSABRI has a profound effect on limiting disease activity that can be observed on magnetic resonance imaging (MRI) scans. In clinical studies, patients treated with TYSABRI had a 92% reduction in new gadolinium-enhancing lesions and an 83% reduction in new or enlarging T2 lesions compared to placebo-treated patients. The reduction in new lesions signifies a decrease in active inflammation within the central nervous system.

Targeted Mechanism

Unlike some immunosuppressants, TYSABRI selectively targets the alpha-4 integrin on inflammatory leukocytes, preventing them from entering the central nervous system. This helps prevent nerve damage by blocking the inflammatory process at a critical juncture, without broadly suppressing the entire immune system.

The Benefits of TYSABRI for Crohn's Disease (CD)

In addition to its use in MS, TYSABRI is approved to treat adult patients with moderately to severely active Crohn's disease who have failed to respond to other therapies. Crohn's disease is an inflammatory bowel disease where inflammatory cells cause swelling in the digestive tract. TYSABRI works by blocking the migration of these inflammatory cells into the gut.

Inducing and Maintaining Remission

Clinical trials have shown that TYSABRI can induce clinical response and remission in patients with active Crohn's disease. In one trial, after 12 weeks of treatment, 37% of patients achieved remission, and 60% saw an easing of symptoms. Patients who responded to induction therapy and continued on TYSABRI saw significantly higher rates of sustained response and remission through week 36 compared to those who switched to placebo.

Sustained Symptom Control

For patients who benefit from TYSABRI, the treatment offers sustained control of symptoms, such as frequent diarrhea, abdominal pain, and overall diminished well-being. The consistent monthly infusion schedule helps to maintain steady symptom management over time. The sustained benefits are particularly valuable for patients who have not found success with conventional therapies or anti-TNF-α agents.

Considerations and Safety Profile

While TYSABRI offers significant benefits, it is associated with serious risks, most notably the risk of progressive multifocal leukoencephalopathy (PML), a rare but serious viral brain infection. Due to this risk, TYSABRI is available only through a restricted distribution program called the TOUCH® Prescribing Program. Regular monitoring and testing for the John Cunningham (JC) virus, which causes PML, are essential.

Comparison of TYSABRI's Action in MS vs. Crohn's Disease


Feature	TYSABRI for Relapsing Multiple Sclerosis (MS)	TYSABRI for Crohn's Disease (CD)
Mechanism of Action	Blocks immune cell migration across the blood-brain barrier.	Blocks immune cell migration into the gut lining.
Primary Benefit	Reduces relapses and slows disability progression.	Induces and maintains clinical response and remission.
Targeted Area	Central nervous system (brain, spinal cord).	Gastrointestinal tract.
Clinical Trial Evidence	Significant reduction in annualized relapse rate (ARR) and disability progression.	Higher rates of clinical response and sustained remission vs. placebo.
Risk of PML	Present due to effect on immune cells; monitored via TOUCH program.	Present due to effect on immune cells; monitored via TOUCH program.

Conclusion

Overall, the benefits of TYSABRI make it a potent and highly effective treatment for specific patient populations with relapsing MS or moderate-to-severe Crohn's disease who have not found success with other therapies. Its unique mechanism of action, which targets the inflammatory process by blocking immune cell migration, leads to significant clinical improvements, including reduced relapses, delayed disability progression, and decreased inflammatory activity in MS. In Crohn's disease, it helps achieve and sustain remission, offering a valuable alternative for patients with inadequate response to conventional treatments. However, the decision to use TYSABRI must always be weighed carefully against the serious risks, particularly PML, through close collaboration with a healthcare provider within the structured TOUCH Prescribing Program.

For more detailed information on natalizumab for Crohn's disease and clinical trial results, one can refer to publications like the New England Journal of Medicine.

Frequently Asked Questions

TYSABRI is used to treat adult patients with relapsing forms of multiple sclerosis (MS), including clinically isolated syndrome, relapsing-remitting disease, and active secondary progressive disease. It is also indicated for moderate-to-severe active Crohn's disease when other therapies have not been effective.

TYSABRI is a monoclonal antibody that binds to a protein called alpha-4 integrin on immune cells. By blocking this protein, it prevents inflammatory immune cells from crossing the blood-brain barrier (in MS) or entering the gut lining (in Crohn's disease), thereby reducing inflammation and nerve or tissue damage.

In clinical trials, TYSABRI was highly effective, reducing the average annual relapse rate by 67% and the risk of sustained disability progression by 42% over two years compared to placebo. It also significantly reduces the number of new brain lesions.

Yes, TYSABRI has been shown to induce clinical response and remission in patients with moderately to severely active Crohn's disease, especially for those who have not responded to conventional therapies. For responders, it helps maintain sustained benefits over time.

The most significant risk is developing progressive multifocal leukoencephalopathy (PML), a rare and potentially fatal brain infection caused by the JC virus. Your risk is higher if you are positive for JC virus antibodies, have been on therapy for over two years, or have a history of immunosuppressant use.

TYSABRI is administered as an intravenous (IV) infusion, typically once every four weeks, by a healthcare professional in a certified infusion center.

A patient's eligibility for TYSABRI depends on a careful risk-benefit assessment with their doctor. For MS, it's typically for relapsing forms, especially if highly active. For Crohn's, it is for patients with moderate-to-severe disease who have had an inadequate response to other therapies.

TYSABRI is a selective immunosuppressant that primarily affects the migration of certain immune cells, rather than broadly suppressing the entire immune system like some other medications. However, it can still increase the risk of infections.