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Oncophage has received Russian approval for the treatment of non-metastatic, intermediate-risk renal cell carcinoma patients. However, the vaccine is unlikely to be approved in the US and EU based on the same data. Though a significant milestone for Antigenics, the company will need to gain approval in the lucrative US and major EU countries in order to increase Oncophage's commercial potential.
The Russian Ministry of Public Health has approved Antigenics' Oncophage (vitespen) for the treatment of non-metastatic renal cell carcinoma (RCC) patients at an intermediate risk of recurrence, with launch anticipated in the second half of 2008. This decision comes despite a lack of approval of Oncophage elsewhere, as well as the significant hurdles that therapeutic cancer vaccines as a class face in general. Indeed, Oncophage has now become one of the few therapeutic cancer vaccines formally approved for use.
Approval was based on a subset analysis of a Phase III clinical trial that randomized 604 RCC patients to receive adjuvant Oncophage or observation alone after surgery. In the entire study population, Oncophage failed to provide an increase in recurrence-free survival. However, in a subset of 362 intermediate-risk patients (high-grade Stage I/II or low-grade Stage III tumors) who were disease-free at baseline, Oncophage provided a statistically significant (p<0.01) improvement in recurrence-free survival of 45% over observation alone, which translated into an average of approximately 1.8 years.
While the Russian regulatory body chose to accept the validity of this subset analysis, the US FDA will not approve investigational product applications based on such data. Upon closer inspection of the trial, approximately one-third of the 604 patients enrolled were treated at Russian centers, 70% of which fell into the intermediate-risk subset of patients. It is therefore clear that the subset analysis may be of greater validity in Russia than in other countries taking party in the study, including the US.
Oncophage is an autologous vaccine based on the gp96 heat-shock protein linked to patients' own tumor-associated antigenic peptides. This allows for the representation of a wide array of antigens unique to each patient's tumor, which in theory should result in greater anti-tumor efficacy. Despite this, the harvesting of tumor tissue from individual patients and the logistics associated with this complicate the manufacture of Oncophage. As a result, it is expected that Oncophage would have a relatively high price. However, Antigenics' chief executive has stated the company's intention to price Oncophage at the 'low to mid-range of other new-generation cancer drugs', may address price concerns.
While Russian approval of Oncophage is a significant milestone for Antigenics, the most lucrative markets (the US and major EU countries) are yet to grant approval. Seeking approval in these countries is likely to be a significantly greater challenge and may require Antigenics to carry out additional clinical testing of Oncophage in order to prove the findings of the subset analysis.
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