The US Food and Drug Administration (FDA) has approved Ipsen’s groundbreaking Sohonos (palovarotene) capsules for the treatment of fibrodysplasia ossificans progressive (FOP), an ultra-rare bone disease.
This approval marks a significant milestone as Sohonos becomes the singular treatment for individuals afflicted by FOP, which causes abnormal bone growth. FOP is estimated to affect the lives of approximately 400 individuals in the US and around 900 individuals worldwide.
Sohonos has gained approval for usage in both adult and pediatric patients aged eight years and older for females, and ten years and older for males dealing with FOP.
Sohonos received Orphan Drug and Breakthrough Therapy Designations from the FDA for the treatment of FOP and was granted Priority Review of the New Drug Application (NDA). The FDA also issued a Rare Pediatric Disease Priority Review Voucher (PRV) to Ipsen that can be used for subsequent drug applications that would not qualify for a priority review.
“The FDA approval of Sohonos is a breakthrough for the US FOP community,” said Howard Mayer, head of R&D at Ipsen, in the company’s news release. “For the first time, doctors have an approved medicine available to them, shown to reduce the formation of new, abnormal bone growth, known as heterotopic ossification (HO), which causes debilitating mobility challenges and has a devastating impact on the lives of people with FOP.”
Fibrodysplasia Ossificans Progressiva (FOP): An Ultra-Rare Genetic Bone Disease
FOP, also known as myositis ossificans, is a genetic connective tissue disorder which manifests through the abnormal formation of bone in regions of the body where bone wouldn’t typically exist (heterotopic ossification), including ligaments, tendons and skeletal muscles. Specifically, this condition triggers a transformation of the body’s skeletal muscles and supple connective tissues into bone, progressively leading to the immobilization of joints and rendering movement arduous or even unfeasible.
Those afflicted by FOP exhibit congenital malformed big toes, and additional skeletal irregularities might arise with age. The irregular, episodic formation of bone in various soft tissue sites often results in stiffness within the affected areas, restricted mobility and eventual fusion of joints (starting with the neck, back, shoulders, elbows and proceeding to the hips, knees, wrists, ankles and jaw).
FOP is an extremely rare disease, occurring in an estimated one out of every two million individuals. The median life expectancy of patients with FOP is 56, making it a severe and often misdiagnosed disease. Early detection can significantly help improve the longevity and quality of life of FOP patients. Sohonos, the first and only approved drug, offers hope to those battling the disease.
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How Does Sohonos Work?
The active ingredient in Sohonos, palovarotene, functions as an agonist of the retinoic acid receptor gamma, which is present in cells that are involved in bone formation. This attachment halts the advancement of the genetic disorder through a reduction in the formation of fresh, abnormal bone growth.
Safety and Effectiveness of Sohonos
The Phase III MOVE trial evaluated the safety and efficacy of palovarotene in decreasing new HO in participants with FOP. The findings were compared with data from participants in the FOP natural history study, who did not receive treatment beyond the standard of care in the natural history study.
The Phase III trial consisted of three parts, with 107 participants enrolled. Part A was the study’s main part, Part B was the two-year (24-month) extension, and Part C was an up-to-two-year post-last dose of study treatment follow-up for skeletally immature participants.
The study results demonstrated that palovarotene effectively reduced annualized HO volume compared with no treatment beyond the standard of care by 54 percent and established the safety profile of palovarotene consistent with the systemic retinoid class.
The most common adverse reactions reported in the Phase III study were mucocutaneous events such as dry skin, lip dryness, alopecia, drug eruption, rash and pruritus, and musculoskeletal events such as arthralgia and premature growth plate closure in growing children.
“Development of medicines for rare diseases takes commitment and belief from everyone involved. We at Ipsen are sincerely grateful to the FOP community of patients and medical experts, as the first-ever treatment in the US for managing FOP would not be possible without their participation in the clinical trials and ongoing support,” said Mayer.
Price of Sohonos
Ipsen has set the average list price of Sohonos to $624,000 annually for a 5-mg daily dose, although the actual dosage depends on the disease severity and weight of the patient.
To ensure that eligible individuals in the US can avail Sohonos, Ipsen has introduced the Ipsen Cares patient support program. This resource is accessible to individuals dealing with FOP and their caregivers, offering educational assistance and addressing queries related to coverage, accessibility and reimbursement.
Other Promising Treatments for FOP
This endorsement places Ipsen in a leading position compared to other pharma companies like Regeneron Pharmaceuticals, which is also working on an investigational drug, garetosmab, for the same condition and anticipates submitting an application for approval to the FDA in 2024.
Ipsen is also concurrently working on an investigational FOP drug, BLU-782, which they have licensed from Blueprint Medicines Corp.
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