Meds & Escalation
You started a biologic for ulcerative colitis (UC), and for a while it worked. Symptoms calmed down, your labs improved, and you got a window of something close to normal. Then the flares crept back. Urgency returned. Blood reappeared. If this sounds familiar, you are dealing with what gastroenterologists call "loss of response," and you have more options than you might think. Understanding what is happening and what questions to bring to your next appointment can make the difference between months of guesswork and a clear path forward.
Why Biologics Stop Working
Loss of response happens to a significant number of UC patients on biologic therapy. Studies estimate that up to one-third of patients on biologics either never fully respond (primary non-response) or lose their initial response over time (secondary loss of response). The reasons differ, and the distinction matters because it shapes your next move.
With secondary loss of response, the most common culprit is immunogenicity. Your immune system recognizes the biologic as foreign and produces anti-drug antibodies (ADAs) that neutralize it or speed its clearance from your body. Drug levels drop, and the medication can no longer keep inflammation in check. Other times, the disease itself shifts, activating inflammatory pathways the biologic was never designed to block.
Therapeutic Drug Monitoring: The First Step
Before changing anything, your GI should order therapeutic drug monitoring (TDM), a blood test that measures the amount of biologic in your system and checks for anti-drug antibodies. TDM turns a vague conversation about "the drug not working" into a data-driven decision.
The results typically point in one of three directions. If your drug levels are adequate and no antibodies are detected, the problem may be that your disease is driven by a pathway the current biologic does not target, and switching to a different drug class is the logical next step. If drug levels are low but antibodies are absent, dose escalation or shortening the interval between infusions or injections can often recapture your response. If drug levels are low and antibody levels are high, continuing the same drug at any dose is unlikely to help, and a switch is warranted. Whether you switch within the same class (for example, from one anti-TNF to another) or to an entirely different mechanism depends on the antibody picture and your treatment history.
Dose Escalation and Optimization
When TDM shows room to optimize your current therapy, dose escalation is often the first adjustment. This might mean a higher dose per infusion, more frequent injections, or adding an immunomodulator like azathioprine or methotrexate to reduce antibody formation and boost drug levels. Real-world data show that clinical response rates after dose escalation range widely, from 20% to 95% depending on the drug and the patient, but for many people it buys meaningful additional time on a therapy that was already partially working.
Switching: Within-Class vs. Between-Class
If optimization fails or antibody levels are too high, switching medications is the next conversation. Within-class switching (for example, moving from infliximab to adalimumab, both anti-TNFs) can work when antibodies are specific to one drug's structure rather than its mechanism. Between-class switching targets a completely different inflammatory pathway, which may be the better bet if you have already tried dose escalation without success or if your GI suspects the underlying biology of your disease has changed.
The good news is that UC patients today have more approved advanced therapies than at any point in history. Beyond anti-TNFs like infliximab and adalimumab, the current landscape includes vedolizumab (a gut-selective integrin blocker) and ustekinumab (an IL-12/23 inhibitor), each with a distinct mechanism.
Oral Small Molecules: A Growing Option
One of the biggest shifts in UC treatment is the arrival of oral small molecule therapies that work differently from injectable biologics. Janus kinase (JAK) inhibitors, including tofacitinib and upadacitinib, block intracellular signaling pathways that drive inflammation. Because they are small molecules rather than large proteins, they do not trigger the same antibody-mediated loss of response that can affect biologics.
Sphingosine 1-phosphate (S1P) receptor modulators, including ozanimod and etrasimod, offer yet another mechanism. These oral drugs work by trapping certain immune cells in lymph nodes, preventing them from migrating to the gut and fueling inflammation. S1P modulators may be particularly worth discussing with your GI if you have risk factors that make JAK inhibitors less ideal, such as cardiovascular concerns or older age.
What to Ask Your GI
Walking into your next appointment with the right questions saves time. Ask whether TDM has been done and what the results show. Ask whether dose escalation or adding an immunomodulator is an option before switching. If a switch is recommended, ask why your GI is choosing a within-class versus between-class change, and whether an oral small molecule could be a fit for your situation. These are reasonable, evidence-based questions that help you participate in the decision rather than passively receiving it.
If your treatment may be losing effect, your symptom trend is critical evidence. Track daily with Aidy so you and your GI can see exactly when things started changing, how fast symptoms progressed, and whether patterns emerge that point toward a specific next step.