P687 Early and sustained improvement in stool frequency and rectal bleeding following 52 weeks of mirikizumab treatment
D’Haens, GR., Hibi, T., Ferrante, M., Bhandari, BR., Berliba, R., Tuttle, JL., Lissoos, T., Krueger, K., Morris, NR et al.
Background: Interleukin (IL)-23 is a key cytokine in inflammatory bowel disease pathogenesis. Mirikizumab (miri), a p19-directed IL-23 antibody, demonstrated efficacy and was well-tolerated in patients with moderate-to-severely active ulcerative colitis (UC) during 52 weeks of a Phase 2 randomised clinical trial (AMAC, NCT02589665). The effects of miri on stool frequency (SF) and rectal bleeding (RB) through Week 52 are reported.
Methods: Patients (Mayo score 6–12 with endoscopic subscore [ES] ≥2) were randomised 1:1:1:1 to receive intravenous (IV) placebo (n = 63), miri 50 mg (n = 63) or 200 mg (n = 62) with possibility of exposure-based (EB) dose increases, or fixed miri 600 mg (n = 61) every 4 weeks (Q4W). Responders to miri at Week 12 (9-point Mayo score decrease ≥2 points and ≥35% change from baseline, with RB=0 or 1 or decrease ≥1) were re-randomised 1:1 into a double-blind maintenance period to receive miri 200 mg subcutaneously (SC) Q4W (n = 47) or every 12 weeks (Q12W; n = 46), and were treated through Week 52. Patients reported UC symptoms, including SF and RB, via a daily diary. Changes from baseline in average Mayo SF and RB subscores at Weeks 2, 4, and 12 were analysed using a mixed model repeated-measures method to account for missingness and baseline characteristics.
Results: Significant improvement in SF was observed as early as Week 2 in the miri 600 mg Q4W group and as early as Week 4 in the miri 200 mg Q4W group (Figure). Similarly, significant improvement in RB was observed as early as Week 2 in both the miri 200 mg Q4W and 600 mg Q4W groups. Patients who received miri 200 mg Q4W or 600 mg Q4W had a significantly greater reduction in both SF and RB compared with placebo at Week 12 (all p < 0.001) (Figure). Patients who achieved clinical response at Week 12 and were treated with miri 200 mg SC Q4W or SC Q12W maintained a low average SF and RB score at Week 52.