This is a randomized, double-blind, placebo-controlled study comparing the safety and efficacy of 2 dosage regimens of palovarotene versus placebo in preventing disease progression in pediatric subjects with multiple osteochondromas (MO).



Eligible Ages
Between 2 Years and 14 Years
Eligible Genders
Accepts Healthy Volunteers

Inclusion Criteria

  • Written, signed, and dated informed subject/parent consent and age-appropriate assent (performed according to local regulations).
  • A clinical diagnosis of MO with disease-causing exostosin 1 or 2 gene mutations.
  • Male or female from 2 to 14 years of age.
  • Female subjects must be premenarchal at screening.
  • A bone age at screening of 14 years or less.
  • Symptomatic MO, defined as five or more clinically-evident osteochondromas and a new or enlarged osteochondroma that occurred in the preceding 12 months, five or more clinically-evident osteochondromas and the presence of a painful osteochondroma, a skeletal deformity, a joint limitation, or prior surgery for a MO-related complication.
  • The ability to undergo whole body MRI with or without sedation/general anesthesia.
  • Use of two effective methods of birth control during treatment, and for 1 month after treatment discontinuation, unless committed to true abstinence from heterosexual sex. Sexually active females of child-bearing potential must also agree to start effective methods of birth control at screening.

Exclusion Criteria

  • Weight under 10 kg.
  • Other syndromic conditions such as Langer-Giedion or Potocki-Shaffer.
  • Any subject with neurologic signs suggestive of spinal cord impingement.
  • Concomitant medications that are strong inhibitors or inducers of cytochrome P450 3A4 activity.
  • Amylase or lipase >2 times the above the upper limit of normal (>2×ULN) or with a history of chronic pancreatitis.
  • Elevated aspartate aminotransferase or alanine aminotransferase above 2.5×ULN.
  • Any surgical implant that is contraindicated for MRI.

Study Design

Phase 2
Study Type
Intervention Model
Parallel Assignment
Intervention Model Description
Multicenter, randomized, double-blind, placebo-controlled
Primary Purpose
Quadruple (Participant, Care Provider, Investigator, Outcomes Assessor)

Arm Groups

ArmDescriptionAssigned Intervention
Palovarotene 2.5 mg daily regimen
  • Drug: Palovarotene 2.5 mg
    Subjects will receive a weight-adjusted dose equivalent of 2.5 mg palovarotene, once daily, for up to 24 months.
Palovarotene 5.0 mg daily regimen
  • Drug: Palovarotene 5.0 mg
    Subjects will receive a weight-adjusted dose equivalent of 5.0 mg palovarotene, once daily, for up to 24 months.
Placebo Comparator
Placebo regimen
  • Other: Placebo
    Subjects will receive placebo, once daily, for up to 24 months.

More Details

Active, not recruiting
Clementia Pharmaceuticals Inc.

Study Contact

Detailed Description

Multiple osteochondromas is a rare condition where children develop multiple benign cartilage-capped bony tumors called osteochondromas on bones throughout the body, resulting in pain, deformity, limb length discrepancy, disability, and eventually arthritis and possible malignancy. The primary objective is to compare the efficacy of two dosage regimens of palovarotene with placebo to prevent the formation of new osteochondromas in pediatric MO subjects with exostosin 1 or exostosin 2 gene mutations. Osteochondroma formation will be assessed by whole body magnetic resonance imaging (MRI). Secondary efficacy objectives are to compare the effect of palovarotene on the volume of osteochondromas as assessed by MRI; and on the annualized rate of new or worsening deformities and MO-related surgeries. The overall safety of palovarotene and the effects of palovarotene on linear growth, bone growth plates, bone mineral density, quality of life, and pain due to osteochondromas will also be studied.


Study information shown on this site is derived from ClinicalTrials.gov (a public registry operated by the National Institutes of Health). The listing of studies provided is not certain to be all studies for which you might be eligible. Furthermore, study eligibility requirements can be difficult to understand and may change over time, so it is wise to speak with your medical care provider and individual research study teams when making decisions related to participation.