Two clinical trials testing an Ipsen drug in rare connective tissue disorders have been placed on partial hold after safety concerns about chronic dosing of the compound emerged.
The partial hold applies to patients under 14 years of age in Phase 2 and Phase 3 tests of the drug, palovarotene. But the Paris-based company, which has US operations in Cambridge, MA, says the FDA is permitting studies to continue testing the drug in patients 14 and older.
Ipsen brought palovarotene into its pipeline earlier this year through the acquisition of Montreal-based Clementia Pharmaceuticals for $1 billion up front. The Ipsen drug is being tested as a treatment for fibordysplasia ossificans progressiva (FOP), a condition in which muscle and connective tissue are gradually replaced by bone. The disorder has no FDA-approved treatments, though steroids and anti-inflammatory drugs have been used to address pain and swelling.
The Ipsen drug is also being tested as a treatment for osteochondroma, a benign tumor. This tumor is found near the growth plate, the bone and cartilage near the ends of the long bones, such as the femur, in children.
Ipsen said Friday that the FDA issued partial holds on both clinical trials after the company submitted safety reports to the agency concerning cases of early growth plate closure in the Phase 3 study testing chronic dosing of palovarotene in FOP patients. Premature closure of the growth plate in children leads to a shortened bone.
No growth plate closures have been reported in the osteochondroma study to date. But Ipsen said that the partial hold was placed on that Phase 2 study as well because of the adverse events observed in the chronic dosing of the drug in the FOP study. Since the osteochondroma study consists of patients younger than 14, the partial hold interrupts the treatment of these patients, and no new patients will be enrolled in that trial.
According to Ipsen, the FDA plans to request additional information within the next 30 days. The company says it is continuing to prepare to file for approval of palovarotene as a treatment for acute flare-ups of FOP.