Entyvio (vedolizumab) works by blocking specific immune cells from traveling into the lining of your gut, where they would otherwise cause the inflammation behind ulcerative colitis and Crohn’s disease. Unlike many other treatments for these conditions, it targets only the gut’s immune response rather than suppressing your immune system body-wide. This gut-selective approach is the defining feature that sets Entyvio apart from older biologics.
How It Stops Inflammation in the Gut
Your immune system relies on white blood cells called T and B lymphocytes to fight threats. In inflammatory bowel disease, these cells flood into the intestinal lining in large numbers, attacking tissue as though it were a foreign invader. To get there, they need a way in. That entry pass is a protein on their surface called alpha-4-beta-7 integrin, which acts like a key. The lock it fits into is a molecule called MAdCAM-1, found on the blood vessel walls of the gut.
When a lymphocyte’s alpha-4-beta-7 integrin binds to MAdCAM-1, the cell crosses from the bloodstream into the intestinal tissue. Entyvio is an antibody that attaches to the alpha-4-beta-7 integrin, physically covering the “key” so it can no longer fit its “lock.” The immune cells get trapped in the bloodstream and never reach the gut wall. With fewer inflammatory cells arriving, the tissue gets a chance to heal.
Why It’s Considered Gut-Selective
Alpha-4-beta-7 integrin appears on only about 3% of circulating T cells, and these are specifically the ones headed for the gut. MAdCAM-1, the molecule those cells bind to, is found almost exclusively on blood vessels in the intestinal tract. Because Entyvio only blocks this particular pairing, it doesn’t interfere with immune cell movement to the brain, lungs, skin, or other organs.
This matters because an older drug in the same class, natalizumab, blocks a broader integrin target (alpha-4) that guides immune cells to the brain as well as the gut. That broader block created a risk of a rare but serious brain infection called progressive multifocal leukoencephalopathy (PML). If natalizumab carried vedolizumab’s same level of risk, researchers estimated roughly 30 cases of PML would have been expected based on cumulative patient exposure. To date, zero confirmed cases of PML have been reported with Entyvio. That distinction is a direct result of its gut-only targeting.
How It’s Given
Treatment starts with intravenous (IV) infusions to build up the drug in your system. You’ll receive at least two IV infusions during this induction phase. After that, you can either continue with periodic IV infusions or switch to a subcutaneous (under-the-skin) injection of 108 mg every two weeks for maintenance. The subcutaneous option, which you can do at home, was approved for patients who’ve already responded to the initial IV doses.
How Quickly It Works
Entyvio is not a fast-acting medication. In studies of ulcerative colitis patients, only about 15% were in clinical remission by week 2. The biggest jump happened between weeks 2 and 6, when the remission rate climbed to roughly 46%. By week 14, about half of patients had reached remission. Response rates followed a similar curve: 27% at week 2, 50% at week 6, and 58% at week 14.
This gradual timeline is a direct consequence of how the drug works. It doesn’t switch off inflammation instantly. It slowly chokes off the supply of new inflammatory cells entering the gut, so healing happens over weeks as existing inflammation resolves on its own. If you’re starting Entyvio, your doctor will likely assess your progress around week 6 to see if the drug is gaining traction.
How Effective It Is Long-Term
The major clinical trials evaluated Entyvio’s performance at one year. In the GEMINI 2 trial for Crohn’s disease, 39% of patients on Entyvio IV were in clinical remission at week 52, compared to about 22% on placebo. A later trial testing a subcutaneous formulation (VISIBLE 2) found 48% remission at week 52 versus 34% on placebo. Among patients who needed to get off corticosteroids, 45% of those on Entyvio achieved steroid-free remission, compared to just 18% on placebo.
For ulcerative colitis, the results followed a similar pattern. Patients who responded to Entyvio during the initial infusion phase and continued on maintenance therapy had significantly higher rates of remission and visible healing of the intestinal lining at one year compared to those switched to placebo.
Common Side Effects
Because Entyvio’s immune effects are largely confined to the gut, its side effect profile is relatively mild compared to drugs that suppress immunity throughout the body. In the GEMINI II trial, the most frequently reported side effects included:
- Nasopharyngitis (common cold symptoms): 15% of patients
- Headache: 13%
- Nausea: 12%
- Fever: 12%
- Joint pain: 11%
- Abdominal pain: 10%
- Back pain: 9%
- Fatigue: 7%
Notably, several of these side effects occurred at similar or even higher rates in the placebo group, which suggests some symptoms overlap with the underlying disease itself. Upper respiratory and urinary tract infections were slightly more common in the Entyvio group (5% each), consistent with a mild localized effect on mucosal immunity.
What to Know Before Starting
Before your first infusion, you’ll be screened for tuberculosis with a skin test or blood test, since biologics can reactivate latent TB. Your vaccination records also need to be current before treatment begins. Live vaccines (such as the live shingles vaccine or MMR) should not be given while you’re on Entyvio or within three months of stopping it, because even a gut-selective immune treatment can potentially reduce your body’s ability to handle a live virus introduced through vaccination.
Entyvio is approved for adults with moderately to severely active ulcerative colitis or Crohn’s disease. It’s often positioned as a treatment for people who haven’t responded well to conventional therapies, though it can also be used earlier in the treatment course depending on your situation and your doctor’s approach.