Schering-Plough expects to respond to FDA's "complete response" letter for Saphris (asenapine) later in the first quarter, the firm said Jan. 14.

The company received the letter regarding its application for Saphris for the acute treatment of schizophrenia in adults and acute treatment of manic or mixed episodes associated with bipolar I disorder.

FDA is seeking supplemental data from the existing database for asenapine but isn't asking for additional clinical trials. In addition, the letter proposes labeling for Saphris, which could bode positively for the drug's regulatory future. FDA's regulations implementing the use of complete response letters - replacing the former "approvable"/"not-approvable" system - says the agency will not consider labeling if applications are way off the mark.

Schering had previously indicated that it did not expect a first round approval for asenapine, given the regulatory process for antipsychotic drugs.

The NDA for asenapine includes data from a clinical trial program involving more than 3,000 schizophrenia and bipolar mania patients. FDA action on the application had been held up by the regulatory backlog at FDA. The original action date for the NDA was in June.

Saphris, gained through Schering's acquisition of Organon, is one of the five pipeline "stars" management highlighted during an R&D meeting in November (¹ Also see "Schering Telescope Points To 5 R&D “Stars,” But TRA Shines Brightest" - Pink Sheet, 1 December, 2008., p. 3). The company has high expectations for the drug, predicting peak sales of more than $1 billion.

However, Schering could face commercial challenges with Saphris. The treatment category is already crowded, dominated by atypical antipsychotics, including generic versions of Johnson & Johnson's Risperdal (risperidone). Generic versions of Eli Lilly's market leading Zyprexa (olanzapine) are also expected to hit the market in 2011.

In fact, Pfizer previously owned rights to asenapine but backed out of a partnering deal with Organon in 2006, citing commercial challenges.

In a recent interview with "The Pink Sheet," Schering-Plough CEO Fred Hassan maintained a positive outlook for the commercial potential of Saphris, citing the large unmet medical need in the market and high rate of medication switching. In addition, Saphris has been shown to have a weight gain advantage over Zyprexa, he added (² Also see "Schering-Plough’s Fred Hassan: An Interview With “The Pink Sheet”" - Pink Sheet, 5 January, 2009., p. 14).

Some analysts have been less enthusiastic on the potential of Saphris. Credit Suisse analyst Catherine Arnold noted in a Nov. 25 report, "The product will likely be relegated to second or third line status given the number of competitors that are already established in this market and the perception that Zyprexa and Risperdal are superior in terms of efficacy." Arnold forecasts sales of Saprhis reaching just over $400 million.

On the other hand, Cowen & Co. analyst Steve Scala is bullish. "We continue to think that the opportunity for asenapine is under-appreciated, as we think an antipsychotic with little to no weight gain and no cardiovascular safety issues is a lay-up blockbuster," he said in a Dec. 3 research note.

-Jessica Merrill (j.merrill@elsevier.com)

Schering-Plough's Saphris Hits FDA Roadblock With "Complete Response"

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