Efficacy and Safety of Selumetinib in Adults With NF1 Who Have Symptomatic, Inoperable Plexiform Neurofibromas

This is a randomized, double-blind, placebo-controlled, 2 arm multicentre, global Phase III study to assess the efficacy and safety of selumetinib compared with placebo in adult participants with NF1 who have symptomatic, inoperable PN.

Primary Outcome Measures

1. Confirmed Partial and Complete Response Rate (ORR) by End of Cycle 16 Using Volumetric MRI Analysis as Determined by ICR (Per REiNS Criteria) in Participants With NF1 Who Have Symptomatic, Inoperable PN.
   Objective response rate is defined as the proportion of participants who have a confirmed CR (defined as disappearance of the target PN, confirmed by a consecutive scan within 3 to 6 months after the first response) or confirmed PR (defined as a target PN volume decrease ≥ 20%, compared to baseline, confirmed by a consecutive scan within 3 to 6 months after the first response) by end of Cycle 16 as determined by ICR per REiNS criteria. Increase in the volume of the target PN by 20% or more compared to baseline or the time of best response after documenting a PR is considered as PD.

Secondary Outcome Measures

1. (First Key Secondary) The Difference of the Means in the Change From Baseline in PAINS-pNF Chronic Target PN Pain Intensity Score at Cycle 12 Between Selumetinib and Placebo, Primary Analysis
   The PAINS-pNF (Pain Intensity Scale for Plexiform Neurofibroma) chronic target PN pain intensity measures the participants' experience of chronic PN-related pain intensity with score from 0 (no chronic tumor pain) to 10 (worst chronic tumor pain). Baseline PAINS-pNF chronic target PN pain score is defined as the average of the available daily PAINS-pNF chronic target PN pain scores in the screening perio, while for Cycle 12, it is defined as the average of the available daily scores for the 28-days cycle up to and including the last day assessment of cycle 12. The difference of the means in the change from baseline at Cycle 12 between selumetinib and placebo in participants with a PAINS-pNF chronic target PN pain score of ≥ 3 at baseline is presented.
2. (First Key Secondary) The Difference of the Means in the Change From Baseline in PAINS-pNF Chronic Target PN Pain Intensity Score at Cycle 12 Between Selumetinib and Placebo, Supplemental Analysis
   The PAINS-pNF (Pain Intensity Scale for Plexiform Neurofibroma) chronic target PN pain intensity measures the participants' experience of chronic PN-related pain intensity with score from 0 (no chronic tumor pain) to 10 (worst chronic tumor pain). Baseline PAINS-pNF chronic target PN pain score is defined as the average of the available daily PAINS-pNF chronic target PN pain scores in the screening perio, while for Cycle 12, it is defined as the average of the available daily scores for the 28-days cycle up to and including the last day assessment of cycle 12. The difference of the means in the change from baseline at Cycle 12 between selumetinib and placebo participants is presented.
3. (Second Key Secondary Endpoint) The Difference of the Means in the Change From Baseline in PlexiQoL Total Score at Cycle 12
   PlexiQoL (Plexiform Neurofibroma Quality of Life scale) is a patient-derived QoL measure specific to adults with NF1-associated PNs. It assesses the impact of PNs on patients' ability to fulfil their human needs. The measure consists of 18 dichotomous items with 0 =Not True and 1 = True. PlexiQoL total scores were calculated by the sum of all items to a maximum of 18, with lower scores indicating better quality of life. The change from baseline to the end of each cycle in PlexiQoL total score was derived as the PlexiQoL total score at the cycle 12 minus baseline PlexiQoL total score and presented.