Safety and Efficacy of Upadacitinib in Treatment of JAK/STAT Pathway Disorders With Activating Mutations

This is a phase 1/2, multi-center trial with an open label dose-escalation phase (OL) followed by a double-blind placebo-controlled randomized withdrawal phase (RW) to study the safety, tolerability, and preliminary efficacy of Upadacitinib in patients with confirmed and symptomatic gain of function mutations in the JAK-STAT pathway. Upon completion of the randomized withdrawal phase, each patient will enter the maintenance phase (MP) where all patients will receive Upadacitinib.

OL Phase (16 weeks): The subject will be escalated two times if tolerated and clinically indicated based upon disease response. The starting dose will be 15 mg per day for patients greater than or equal to 12 years of age (and at least 30 kg in weight). The subject will remain at this dose level for 28 days. The subject will visit the clinical site on day 1 of each dose escalation visit and then will be remotely monitored (phone call and laboratory monitoring to check complete blood counts) on Day 3 and Day 10.

Patients must have a disease status score of 2 or higher utilizing the Primary Immune Regulatory Deficiency (PIRD) Disease Modules prior to initiation of dose-escalation of the drug. The PIRD score is a disease scoring method that capture the clinical manifestations of all PIRDs including JAK/STAT GOF disorders. The PIRD scores for clinical improvement across organ systems for each patient will standardize the ability to quantify improvement across divergent disease phenotypes and assess outcomes based on clinical improvement within each disorder. Patients who demonstrate a response to study treatment, as determined by improvement in PIRD score, may proceed to the RW Phase. Patients who do not meet eligibility criteria for the RW Phase will enter MP.

During the OL Phase, the optimal treatment dose (OTD) for each patient will be determined. OTD will be defined as the dose that achieved complete response or partial response based on the PIRD scores.

RW Phase (8 weeks): For the double-blind randomized withdrawal phase, patients will be randomized to receive either the Optimum tolerated dose (OTD) dose from the OL phase or Placebo using a 1:1 randomization ratio. Subject will come to the study site every 4 weeks. The subject can discontinue the RW phase if he/she experiences a flare (worsening of disease symptoms) and will enter the Maintenance Phase outlined below. For measuring disease flare Primary Immune Regulatory Disorders (PIRD) score will be used. It will be deemed a flare if the score increases by ≥1 in disease manifestation. During the RW-phase, the reference for a disease flare (for the primary endpoint assessment) will be the end of the OL phase PIRD score.