An Efficacy and Safety Study of Palovarotene to Treat Preosseous Flare-ups in FOP Subjects
An Efficacy and Safety Study of Palovarotene to Treat Preosseous Flare-ups in FOP Subjects
Fibrodysplasia ossificans progressiva (FOP) is a rare, severely disabling disease
 characterized by painful, recurrent episodes of soft tissue swelling (flare-ups) that result
 in abnormal bone formation in muscles, tendons, and ligaments. Flare-ups begin early in life
 and may occur spontaneously or after soft tissue trauma, vaccinations, or influenza
 infections. Recurrent flare-ups progressively restrict movement by locking joints leading to
 cumulative loss of function and disability. Mouse models of FOP have demonstrated the ability
 of retinoic acid receptor (RAR) gamma agonists to prevent heterotopic ossification (HO)
 following injury. The purpose of the study is to evaluate whether palovarotene, an RAR gamma
 agonist, will prevent HO during and following a flare-up in subjects with FOP.
The primary objective is to evaluate the ability of different doses of palovarotene to
 prevent HO at the flare-up site in subjects with FOP as assessed by plain radiographs.

 This is a Phase 2, multi-center, randomized, double-blind, sponsor-unblinded,
 placebo-controlled study. Two cohorts of subjects will be randomized into different dosing
 regimens of palovarotene for a 6-week (42 days) treatment period. The study will consist of
 three periods:

 1. A Screening period to occur within 7 days of a distinct flare-up. The first dose of
 study drug will be taken within 7 days of the flare-up initiation.

 2. A double-blind treatment period of 6 weeks (42 days) duration.

 3. A follow-up period of 6 weeks (42 days) duration.

 An initial cohort (Cohort 1) of subjects will be randomly assigned 3:1 to either palovarotene
 or placebo daily for 42 days. Subjects randomized to palovarotene in Cohort 1 will receive an
 initial daily dose of 10 mg for 14 days followed by 5 mg daily for 28 days.

 In Cohort 2, new FOP subjects meeting all inclusion/exclusion criteria will be randomly
 assigned 3:3:2 to two dose regimens of palovarotene (10 mg for 14 days and 5 mg for 28 days;
 5 mg for 14 days and 2.5 mg for 28 days) or placebo daily for 42 days. Doses will be
 weight-adjusted and subjects randomized within three weight-range categories (20 to <40 kg,
 40 to <60 kg, and ≥60 kg).

 Subjects completing the study and still meeting eligibility requirements will be given the
 opportunity to enroll into an open-label extension study.
Inclusion Criteria:

 -  Written, signed, and dated informed subject/parent consent or age-appropriate assent.

 -  Subjects clinically diagnosed with classic Fibrodysplasia Ossificans Progressiva
 (FOP).

 -  Symptomatic onset of a distinct flare-up within 7 days of Study Day 1 (start of study
 drug) and defined by the presence of at least two of six of the following symptoms:
 pain, soft tissue swelling, decreased range of motion, stiffness, redness, and warmth.
 Flare-up must be confirmed by the physician at the Screening visit.

 -  Flare-up is at an appendicular area (upper or lower extremity), abdomen, or chest; and
 subject has received, is receiving, or is willing to receive treatment per standard of
 care, which may or may not include oral prednisone (2 mg/kg PO to a maximum dose of
 100 mg daily) for 4 days.

 -  Abstinent or using two highly effective forms of birth control.

 -  Subjects must be accessible for treatment and follow-up. Subjects living at distant
 locations from the investigational site must be able and willing to travel to a site
 for the initial and all follow-up visits.

 Exclusion Criteria:

 -  Weight <20 kg.

 -  Intercurrent non-healed fracture at any location.

 -  Complete immobilization of joint at site of flare-up.

 -  The inability of the subject to undergo imaging assessments using plain radiographs.

 -  If currently using vitamin A or beta carotene, multivitamins containing vitamin A or
 beta carotene, or herbal preparations, fish oil, and unable or unwilling to
 discontinue use of these products for the duration of the study.

 -  Exposure to synthetic oral retinoids in the past 30 days prior to Screening (signature
 of the informed consent).

 -  Concurrent treatment with tetracycline due to the potential increased risk of
 pseudotumor cerebri.

 -  History of allergy or hypersensitivity to retinoids or lactose.

 -  Concomitant medications that are inhibitors or inducers of CYP450 3A4 activity.

 -  Amylase or lipase >1.5x above the upper limit of normal or with a history of chronic
 pancreatitis.

 -  Elevated aspartate aminotransferase or alanine aminotransferase >2.5x the upper limit
 of normal.

 -  Fasting triglycerides >400 mg/dL with or without therapy.