Sakal forecasts $400 million in U.S. sales of Belviq in 2018.

Citi's Hidemaru Yamaguchi:

"We expect a 2013 launch for Belviq, with sales of $25.17 million in FY3/13, $125.86 million in FY3/14, $377.57 million in FY3/15, $566.36 million in FY3/16, and $623 million in FY3/17."

Barclays' Atsushi Seki:

"We revise our forecasts for Eisai to factor in sales of the obesity drug Belviq. We maintain our 2-EW rating on a peer comparison and expect investors to now focus on the drug's pricing, insurance coverage, and competition. This is not a high-margin drug for Eisai; we think gross margin could range from 30–50% depending on sales. We also expect Eisai to shoulder 90% of the costs for an upcoming clinical testing of the drug’s long-term safety and accordingly raise our forecast for R&D spending."

Lastly, the most optimistic Belviq outlook comes from Goldman Sachs' Steve Chesney:

"In our view, FDA approval without the need for additional pre-approval trials is a positive for Eisai. Approval came with some caveats, however, including that dosing should be stopped if 5% weight loss is not achieved within 12 weeks. Based upon the Belviq clinical data (58% of patients fail to achieve 5% weight loss by week 12) and the commercial experience of other weight loss drugs with similar efficacy, we believe lack of efficacy will significantly limit uptake for Belviq… Although we forecast $1.1bn billion in Belviq sales, contributing 13% to our FY3/17 top line, given the terms of the in-licensing deal (avg. 34% of sales to purchase from ARNA and additional $1.2bn purchase price adjustments on first $2.5bn of sales) we forecast 39% average GP margin, well below Eisai’s FY3/12 consolidated GP margin of 73%."

The consensus view from Japanese analysts seems to be that Eisai is getting a raw deal in its partnership with Arena, suggesting (without saying explicitly) tht perhaps Eisai needs to buy Arena to make Belviq profitable. But with growth slowing due to the loss of patent exclusivity for the Alzheimer's drug Aricept and the setbacks with its breast cancer drug Halaven, does Eisai have the financial resources necessary to make a run at Arena?

--Written by Adam Feuerstein in Boston.

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Adam Feuerstein writes regularly for TheStreet. In keeping with company editorial policy, he doesn't own or short individual stocks, although he owns stock in TheStreet. He also doesn't invest in hedge funds or other private investment partnerships. Feuerstein appreciates your feedback; click here to send him an email.

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