A Study of Mirikizumab (LY3074828) in Children and Teenagers With Ulcerative Colitis (UC)

Clearance of mirikizumab was evaluated. The PK of mirikizumab is characterized at interim analysis points using mixed-effect (population PK) modelling approaches using the available induction and maintenance mirikizumab concentration data.

Clinical remission at week 52 is defined as achieving a 9-point modified Mayo score (MMS) for rectal bleeding (RB) = 0, stool frequency (SF) = 0 or 1 and endoscopy (ES) = 0 or 1 (excluding friability). The MMS is a composite score of ulcerative colitis disease activity calculated as the sum of three subscores: SF subscore, based on the participant's diary and scored from 0 (normal number of stools) to 3 (5 or more stools than normal); RB subscore, based on the participant's diary and scored from 0 (no blood seen) to 3 (blood alone passed); ES subscore, based on colonoscopy or sigmoidoscopy and scored from 0 (normal or inactive disease) to 3 (severe disease, spontaneous bleeding,ulceration.

Clinical response at week 52 is defined as a decrease in the 9-point modified Mayo score (MMS) [rectal bleeding, stool frequency and the endoscopic findings] inclusive of ≥2 points and ≥30% from baseline with either a decrease of rectal bleeding subscore of ≥1 or rectal bleeding subscore of 0 or 1. The MMS is a composite score of ulcerative colitis disease activity calculated as the sum of three subscores: SF subscore, based on the participant's diary and scored from 0 (normal number of stools) to 3 (5 or more stools than normal); RB subscore, based on the participant's diary and scored from 0 (no blood seen) to 3 (blood alone passed); ES subscore, based on colonoscopy or sigmoidoscopy and scored from 0 (normal or inactive disease) to 3 (severe disease, spontaneous bleeding, ulceration)

Corticosteroid-free clinical remission was defined as an SF subscore = 0 or 1, RB subscore = 0, ES ≤ 1 (excluding friability), and have not received corticosteroids for ≥ 12 weeks in the 52-Week Treatment Period. Each component subscore ranged from 0 to 3 and total score range of the MMS was from 0 to 9, with higher scores indicating more severe disease.

The PUCAI is a clinician-administered, 6-item questionnaire that measures: abdominal pain; RB; stool consistency; number of stools; nocturnal stools; and activity level. For PUCAI score all items are answered as an average over the 'past 2 days'. A total disease activity score is calculated from 0 to 85, with Severe 65-85; Moderate:35-60; Mild:10-30, and None:<10. The clinician will record the participant or caregiver/legal guardian responses for the PUCAI electronically as source data in the tablet device at appropriate visits. PUCAI clinical remission is defined as a PUCAI score of <10 points.

PUCAI clinical response is defined as a reduction in baseline PUCAI score of ≥20 points.

Endoscopic remission at week 52 is defined as achieving a Mayo endoscopic subscore of 0 or 1 (excluding friability) at Week 52. ES subscore is based on colonoscopy or sigmoidoscopy and scored from 0 (normal or inactive disease) to 3 (severe disease, spontaneous bleeding, ulceration).

Symptomatic remission at week 52 is defined as a Mayo score for RB=0, SF=0 or 1 with ≥ 1 point decrease from baseline.

SF subscore, based on the participant's diary and scored from 0 (normal number of stools) to 3 (5 or more stools than normal).

RB subscore, based on the participant's diary and scored from 0 (no blood seen) to 3 (blood alone passed).

Observed height velocity by gender and age group was calculated. Age groups for which this was summarized were 2 to <8, 8 to <12, and 12 to <18. Observed height velocity by gender and age group was calculated at baseline according to the following formula: (Present Height [cm] - Previous Height [cm])/Interval (months) Between Measurements × 12.

Change from Baseline in body weight by gender and age group was calculated.

Histologic-endoscopic mucosal remission is defined as achieving both histologic remission and endoscopic remission. Histologic remission is defined as Geboes histological subscores of 0 for parameters: 2B (neutrophils in lamina propria), 3 (neutrophils in epithelium), 4 (crypt destruction), and 5 (erosion or ulceration).

The Abdominal Pain NRS is a single participant-reported item that measures the "worst abdominal pain in the past 24 hours" using a 6-point scale ranging from 0 (no pain) to 5 (worst possible pain) for 8-11 years old, and 11-point NRS ranging from 0 (no pain) to 10 (worst possible pain) for children < 8 years old as completed by a caregiver and those 12-17 years old. Abdominal Pain NRS Score is calculated by averaging data from all available daily diary entries of abdominal pain NRS for a 7 day period. A negative change from baseline indicates improvement in the participant's Abdominal Pain NRS.

The Abdominal Pain NRS is a single participant-reported item that measures the "worst abdominal pain in the past 24 hours" using a 6-point scale ranging from 0 (no pain) to 5 (worst possible pain) for 8-11 years old, and 11-point NRS ranging from 0 (no pain) to 10 (worst possible pain) for children < 8 years old as completed by a caregiver and those 12-17 years old. Abdominal Pain NRS Score is calculated by averaging data from all available daily diary entries of abdominal pain NRS for a 7 day period. A negative change from baseline indicates improvement in the participant's Abdominal Pain NRS.