ObjectiveTo evaluate the efficacy and safety of tofacitinib in patients with ankylosing spondylitis (AS) by prior biologic disease‐modifying antirheumatic drug (bDMARD) use.MethodsData from a placebo‐controlled, double‐blind study of patients with active AS were analyzed. Patients received tofacitinib 5 mg twice daily (BID) or placebo to week 16; all received open‐label tofacitinib 5 mg BID to week 48 and were stratified by prior treatment (bDMARD‐naive or tumor necrosis factor inhibitor [TNFi]–inadequate responder [IR], including bDMARD‐experienced [non‐IR]). Disease activity/safety were assessed throughout.ResultsOf 269 patients, 207 (77%) were bDMARD‐naive; 62 (23%) were in the TNFi‐IR subgroup. TNFi‐IR patients had higher baseline BMI (28.0 vs. 26.1 kg/m²), longer symptom duration (14.4 vs. 13.2 years), and lower concomitant conventional synthetic DMARD use (14.5% vs. 30.9%) than bDMARD‐naive patients. At week 16, for most outcomes, tofacitinib efficacy exceeded placebo for both subgroups and was sustained to week 48. At week 16, tofacitinib versus placebo differences were similar between bDMARD‐naive and TNFi‐IR patients (Assessment in Spondyloarthritis international Society 40 treatment difference [95% confidence interval]: 30.8% [19.1%‐42.6%] vs. 19.4% [1.7%‐37.0%]). Adverse event (AE) proportions were similar between tofacitinib‐treated bDMARD‐naive/TNFi‐IR patients (77.5%/77.4%) at week 48 with no deaths. A numerically higher proportion of tofacitinib‐treated TNFi‐IR versus bDMARD‐naive patients discontinued study drug (12.9% vs. 3.9%) or dose reduced/temporarily discontinued due to AEs (19.4% vs. 11.8%).ConclusionTofacitinib efficacy exceeded placebo at week 16 for bDMARD‐naive/TNFi‐IR patients and was sustained to week 48. The absolute magnitude of responses was generally greater in bDMARD‐naive patients versus TNFi‐IR patients. More TNFi‐IR versus bDMARD‐naive patients discontinued or dose reduced/temporarily discontinued tofacitinib due to AEs. Small sample size and sample size differences between subgroups limited the interpretation.