Allos Therapeutics Inc. has withdrawn its European Marketing Authorisation Application (MAA) for its investigational radiation sensitiser Revaproxyn (efaproxiral, Efaproxyn in the United States) for use as an adjunct to whole brain radiation therapy (WBRT) for the treatment of patients with brain metastases originating from breast cancer.
The company made this decision as a result of the Rapporteurs' Day 180 Joint Assessment Report, which concluded that the current data package was not sufficient to support approval. The MAA was based upon the results of the company's Phase 3 reach trial, which demonstrated a statistically significant survival benefit in patients with brain metastases originating from breast cancer, a subgroup of patients that was not prospectively defined as an intent-to-treat subgroup, states a company release.
"We are disappointed that withdrawal of the MAA is necessary at this time. However, we were able to address many of the CHMP's questions and concerns regarding Revaproxyn and believe that our on-going enrich trial, if positive, together with the other supporting data, should allow us to address the CHMP's remaining concerns and provide the additional data necessary to support the future approval of Revaproxyn for marketing in Europe. Furthermore, the withdrawal of the MAA in Europe does not affect the status of our New Drug Application for Efaproxyn in the United States and we remain committed to completing the enrich study as expeditiously as possible," said Michael E. Hart, president and chief executive officer of Allos.
The release further informs that in June 2004, the company received an approvable letter from the US Food and Drug Administration for its New Drug Application to market Efaproxyn for the treatment of patients with brain metastases originating from breast cancer. The key contingency identified in the approvable letter is the successful completion of an additional clinical trial providing sufficient evidence to confirm the positive survival benefit observed in the breast cancer subset in the Phase 3 reach trial. The company's on-going enrich trial, initiated in February 2004, is designed to generate data that, if positive, would satisfy FDA's requirement for confirmation of the reach trial results.
Efaproxyn is the first synthetic small molecule designed to sensitise hypoxic, or oxygen-deprived, areas of tumours during radiation therapy by facilitating the release of oxygen from haemoglobin, the oxygen-carrying protein contained within red blood cells, and increasing the level of oxygen in tumours.