Protherics of the UK has pulled back its European marketing application for Voraxaze, an adjunctive therapy for patients with impaired kidney function who are experiencing, or are at risk of, toxicity from the chemotherapy methotrexate.

The move follows a request by European regulators for further information on marketing as well as additional data about the potential interaction between Voraxaze (carboxypeptidase G2) and leucovorin, a standard supportive therapy given alongside high-dose methotrexate. The company says it will not be able to meet these requests in the timeframe available, and so has had to withdraw its application for the time being.

US approval in 2009?

Across the Atlantic, the US Food and Drug Administration has also requested additional manufacturing and stability data, as well as a 12-patient study to assess the drug’s interaction with leucovorin. But the agency has agreed that Voraxaze can be re-filed as a rolling submission early next year, which means that it could be on the market there in 2009.

The company is hoping that the extra information it will submit in the USA will also be enough to satisfy the European Medicines Agency’s requests and, if this is the case, says it will consider resubmitting the drug for approval in Europe.

Protherics has also kicked off several pilot studies to explore Voraxaze’s potential as a routine adjunct to high-dose methotrexate. If these studies are successful, the group says it will discuss the data with the regulatory agencies in the US and Europe to determine the development programme required for approval in this setting, which could present a much larger market opportunity.

In the meantime, the company will continue supplying Voraxaze in Europe on a named-patient basis for intervention use in those at risk of severe or life-threatening methotrexate toxicity.

Shares in the group had slipped nearly 3.5% in early morning trading on the London Stock Exchange following the news.