Berlex Laboratories, the US affiliate of German drugmaker Schering, is facing a significant delay in bringing its bone metastasis agent Bonefos (clodronate) to market in the USA, after the Food and Drug Administration said it would not approve the drug until an ongoing clinical trial is completed.

A delay in the Bonefos programme had been a near certainty after the FDA issued an ‘approvable’ letter for the drug earlier this year [[10/01/05b]]. But the news that the agency will insist on waiting for the completion and analysis of Schering’s B-34 study of the drug in breast cancer patients is a blow, given that this trial is not due to complete until 2008.

Bonefos is already on the market in 67 countries outside the US for the treatment of tumour-related breakdown of the bones and excessive calcium in the blood, but sales in these uses have been modest, at around 50 million euros in 2004. The bone metastasis indication had been expected to give the product a major sales boost – with analysts’ estimates of its peak sales potential swelling to between 300 and 700 million euros - at a time when Schering needs a new cancer product to boost its flagging oncology franchise.

Turnover for the cancer franchise in the first quarter of this year declined 11% to 94 million euros, mainly because of the loss of patent protection on Fludara (fludarabine) in the USA [[26/04/05a]].

The delay is particularly disappointing for Schering because other drugs to treat bone metastases – including Novartis’ Zometa (zoledronic acid), and Roche’s Bondronat (ibandronic acid) – have been selling well. As an oral medication, Bonefos had been expected to build market share quickly alongside these injectable competitors.