Sohonos

Sohonos was intended to reduce the abnormal formation of bone in joints, muscles, tendons and ligaments in adults and children (over 8 years of age in girls and over 10 years of age in boys) with FOP. It contains the active substance palovarotene and was to be available as capsules to be taken by mouth every day.

Sohonos was designated an ‘orphan medicine’ (a medicine used in rare diseases) on 19 November 2014 for the treatment of FOP. Further information on the orphan designation can be found on the Agency’s website: ema.europa.eu/medicines/human/orphan-designations/eu3-14-1368.

The active substance in Sohonos, palovarotene, belongs to a class of medicines known as retinoids. It attaches to the retinoic acid receptor (gamma), which is present in cells that are involved in bone formation. By attaching to these receptors, the medicine switches on processes that reduce bone formation. This was expected to relieve the symptoms of the condition.

The company provided results from one main study involving 107 adults and children with FOP. All study participants were given Sohonos and the study results were compared with those of a second study involving 114 patients with FOP who received no treatment.

The main measure of effectiveness in the main study was the change in the amount of newly developed heterotopic ossifications in patients.

The Agency considered that no firm conclusions could be drawn on the benefits of the medicine, as the applicant’s conclusion was based on a post-hoc analysis which was neither scientifically nor clinically justified and pre-specified study objectives were not met. In addition, results from other studies and the limited long-term clinical data available did not support efficacy. Regarding safety, the risk of premature physeal closure (a disruption to the areas of new bone growth in the end of long bones, which keeps them from growing normally), which is a known risk with retinoid treatment in growing patients, could not adequately be mitigated with the risk minimisation measures proposed by the company. In addition, the Agency considered that some questions regarding the quality of the active substance had not been resolved.

Therefore, the Agency’s opinion was that the benefits of Sohonos did not outweigh its risks and it recommended refusing marketing authorisation.

The company informed the Agency that there are no consequences for patients in clinical trials or in compassionate use programmes with Sohonos.

If you are in a clinical trial or compassionate use programme and need more information about your treatment, speak with your doctor.