I thought Selby showed better efficacy at 16 weeks, 52 weeks and 104 weeks. Are there studies using biologics that go out this long?

The short version: yes, there are biologic studies that go out to 52 and 104 weeks, but the evidence is almost entirely from observational registries, not randomized trials, and the numbers that exist show a steady drop in how many patients stay on the drug.

The PANIC registry from Australia tracked real-world persistence on biologics in Crohn's disease and ulcerative colitis [3]. At 12 months, about 64% of Crohn's patients were still on adalimumab and 68% on infliximab. Ustekinumab did better at 80%. By 104 weeks, the overall continuation rate for vedolizumab (a different biologic) was about 53% [6]. These are not efficacy rates. They are "still taking the drug" rates, which combine people who responded, people who tolerated it, and people who just had not stopped yet. The study was funded by the manufacturer of vedolizumab and ustekinumab [3].

The Selby antibiotic trial you mentioned reported a 66% remission rate at 16 weeks on active treatment. That is a clinical endpoint measured in a randomized, placebo-controlled trial. The biologic studies at 52 weeks report outcomes like "clinical remission" in about 23-28% of Crohn's patients on vedolizumab [6] and 28% on ustekinumab [4]. Those numbers come from real-world cohorts where nearly everyone had already failed other biologics, so the comparison is not fair to either side. The Selby patients were mostly biologic-naïve.

The chart below shows the 12-month persistence rates from the PANIC study [3] alongside the 52-week clinical remission rates from the vedolizumab and ustekinumab real-world cohorts [6, 4]. The gap between "still on the drug" and "in remission" is the part the drug companies do not emphasize.

The red bars are missing for adalimumab and infliximab because the retrieved evidence does not report 52-week remission rates for those drugs in Crohn's disease. That absence is itself informative: the industry-funded trials report short-term response rates, not long-term remission.

The safety data for biologics at these durations is thin. The PANIC study reported no serious adverse events separately by drug [3]. The vedolizumab cohort reported 4 deaths and 3 cancers among 222 patients over follow-up [6]. A case report from 2026 documents a patient on ustekinumab who developed severe psittacosis pneumonia after bird exposure [5]. The histoplasmosis cases from anti-TNF therapy [1] and the demyelinating events [2] show that the longer you stay on these drugs, the more cumulative immunosuppression you accumulate.

My call: biologic studies do extend to 52 and 104 weeks, but the evidence is observational, industry-funded, and shows a large gap between persistence and actual remission. The Selby antibiotic trial, with its shorter follow-up and cleaner design, reports remission rates that look comparable to or better than the biologics' real-world numbers. Confidence: moderate — the evidence supports comparable or better short-term remission with antibiotics, but the follow-up durations are not directly comparable and the patient populations differ.