Osseor: Withdrawal of the application to change the marketing authorisation

Protelos and Osseor are identical medicines that contain the active substance strontium ranelate. They are available as sachets containing strontium ranelate (2 g) as granules to be made up into a suspension to be taken by mouth.

Protelos/Osseor has been authorised since September 2004. It is currently used to treat severe osteoporosis (a disease that makes bones fragile) in post-menopausal women and men who have a high risk of fracture.

Protelos/Osseor was also expected to be used to treat osteoarthritis (a long-term disease that damages joints and makes them stiff and painful) in the knee and hip.

In osteoarthritis, the cartilage, a smooth layer that lines the joints and helps them to move easily, is gradually lost, and the bone underneath becomes damaged and exposed. This causes pain and stiffness when the joint moves. Strontium ranelate, the active substance in Protelos/Osseor, is expected to stimulate formation of new cartilage and reduce bone breakdown.

The applicant presented data from one main study involving 1,683 patients with osteoarthritis of the knee. In this study, strontium ranelate 1 or 2 g was compared with placebo (a dummy treatment). The main measure of effectiveness was the effect in slowing the loss of cartilage from the joint as measured by X-rays after 3 years of treatment.

The applications were withdrawn after the CHMP had evaluated the documentation provided by the company and formulated lists of questions. After the CHMP had assessed the company's responses to the last round of questions, there were still some unresolved issues.

Based on the review of the data and the company's response to the CHMP lists of questions, at the time of the withdrawal, the CHMP had some concerns and was of the provisional opinion that Protelos/Osseor could not have been approved for the treatment of osteoarthritis.

The CHMP noted that the size of the benefit seen in the study was small and the long-term benefit unclear, whereas the medicine had an established risk of serious side effects. In addition, the Committee had some concerns about the way in which the loss of cartilage had been evaluated. Therefore, at the time of the withdrawal, the CHMP was of the opinion that the benefits of Protelos/Osseor in the treatment of osteoarthritis did not outweigh its risks.

In its letter notifying the Agency of the withdrawal of the applications, the company stated that the withdrawal was due to the fact that the data so far available were insufficient to address the CHMP's concerns.

The company informed the CHMP that there are no consequences for any ongoing clinical trials with Protelos/Osseor.

There are no consequences on the use of Protelos/Osseor in its authorised indications.