Tofacitinib is an oral, small molecule Janus kinase inhibitor for the treatment of ulcerative colitis (UC). The efficacy and safety of tofacitinib were demonstrated in a dose-ranging phase 2 induction trial, three phase 3 randomized, placebo-controlled trials (OCTAVE Induction 1 and 2; and OCTAVE Sustain), and an ongoing, open-label, long-term extension trial (OCTAVE Open) in patients with moderately to severely active UC. Here, we assessed short- and long-term efficacy and safety of extended induction (16 weeks) with tofacitinib 10 mg twice daily (BID) in patients who failed to respond to initial induction (8 weeks) treatment.In patients who achieved a clinical response following extended induction (delayed responders), the efficacy and safety of tofacitinib were evaluated up to Month 36 of OCTAVE Open.52.2% of patients who did not achieve clinical response to 8 weeks' treatment with tofacitinib 10 mg BID in the induction studies achieved a clinical response following extended induction (delayed responders). At Month 12 of OCTAVE Open, 70.3%, 56.8%, and 44.6% of delayed responders maintained clinical response and achieved endoscopic improvement and remission, respectively. Corresponding values at Month 36 were 56.1%, 52.0%, and 44.6%. The safety profile of the subsequent 8 weeks was similar to the initial 8 weeks.Overall, the majority of patients achieved a clinical response after 8 or 16 weeks' induction therapy with tofacitinib 10 mg BID. Tofacitinib 10 mg BID, administered as induction therapy for up to 16 weeks, had a comparable safety profile to 8 weeks' induction therapy. Most delayed responders at Month 36 were in remission.