An Efficacy and Safety Study of Palovarotene for the Treatment of MO (MO-Ped)


Clementia Pharmaceuticals

Status and phase

Phase 2


Exostoses, Multiple Hereditary


Other: Placebo
Drug: Palovarotene 5.0 mg
Drug: Palovarotene 2.5 mg

Study type


Funder types



2017-002751-28 (EudraCT Number)

Details and patient eligibility


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).

Full 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 was assessed by whole body magnetic resonance imaging (MRI). Secondary efficacy objectives were to compare the effects of palovarotene with placebo on the volume of osteochondromas as assessed by MRI; the proportion of subjects with no new osteochondromas as assessed by whole-body MRI; the annualized rate of new or worsening deformities; the annualized rate of MO-related surgeries; and palatability. The overall safety and pharmacokinetics of palovarotene and the effects of palovarotene on linear growth, bone growth plates, bone mineral density, quality of life, and pain due to osteochondromas was also studied.


193 patients




2 to 14 years old


No Healthy Volunteers

Inclusion and exclusion criteria

Key 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.

Key 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.

Trial design

Primary purpose




Interventional model

Parallel Assignment


Quadruple Blind

193 participants in 3 patient groups, including a placebo group

Palovarotene 2.5 mg daily regimen
Experimental group
Drug: Palovarotene 2.5 mg
Palovarotene 5.0 mg daily regimen
Experimental group
Drug: Palovarotene 5.0 mg
Placebo regimen
Placebo Comparator group
Other: Placebo

Trial documents

Trial contacts and locations



Data sourced from

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