Salix Pharmaceuticals, Ltd. (SLXP) and Progenics Pharmaceuticals (PGNX) recently announced that the FDA’s advisory panel will review Salix’ supplemental new drug application (sNDA) for Relistor for opioid-induced constipation (OIC) in patients with chronic pain.
Salix had received a complete response letter (CRL) from the FDA in Jul 2012 for the Relistor sNDA. In the CRL, the FDA had asked for additional data.
The FDA’s concerns regarding the class of drugs (peripheral mu-opioid antagonist) to which Relistor belongs were based on a potential cardiovascular (:CV) safety signal observed in a 12-month safety study conducted with another peripheral mu-opioid antagonist for the treatment of OIC in patients with chronic non-cancer pain. While the Relistor sNDA did not show any CV signal, the FDA expressed concern regarding the lack of a control population for the long-term safety data.
The FDA also emphasized the need to provide consistent advice regarding major adverse cardiovascular event (MACE) studies that should be conducted by companies developing drugs belonging to this class for the specified indication.
Salix had conducted an end of review meeting in Oct 2012 in order to gain a better understanding of the CRL. Salix had also filed a formal appeal regarding the CRL. According to Salix, currently available post-marketing, clinical and preclinical data could be enough to gain approval. The FDA will arrive at a decision on the appeal once the meeting takes place. A date is yet to be finalized for the advisory panel meeting.
The panel will mainly discuss the potential for drugs in this class to cause withdrawal symptoms, the safety data available on Relistor where a potential CV signal is concerned and the need and timing (pre-approval versus post-approval) for conducting MACE studies with drugs of this class.
The FDA’s decision regarding the advisory panel meeting comes as a positive surprise for Salix and shares were up 5% on the news. While we believe an additional study will most likely be required for approval, we do not expect a significant delay in the approval process for Relistor.
Relistor is a subcutaneous injection that is currently approved for the treatment of OIC in patients with advanced illness who are receiving palliative care, when response to laxative therapy has not been sufficient. Relistor sales came in at about $7.6 million in the first quarter of 2013.
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