Obese patients have seen more choices for treatments over the past year, as new obesity drugs from VIVUS (VVUS) and Arena Pharmaceuticals (ARNA) have launched. A third drug, Orexigen's (NASDAQ: OREX) Contrave, looks as if it could be on the market by the middle of next year after a safety study ruled out excessive cardiovascular risk.

The best obesity drug, though, may still be in the pipeline.

Quick weight loss
Privately held Zafgen released phase 2 data this month showing that its obesity drug beloranib was capable of helping patients lose 24 pounds or about 10.8% of their body weight after just 12 weeks on the highest dose of the drug.

By comparison VIVUS', Arena's, and Orexigen's drugs helped patients lose 5.8% to 9.8% of their body weight over one year. Novo Nordisk's (NVO 0.02%) Victoza, which is a diabetes drug that also helps patients lose weight, produced similar results.

The placebo-adjusted numbers are even more striking, since over 12 weeks, patients who received placebo in Zafgen's study lost less than 0.4% of their body weight, while over a year, patients in an obesity study typically lose 1% to 3% of their body weight while getting the dummy pill.

Best drug?
The difference between 10.8% for beloranib and 9.8% for VIVUS' Qsymia isn't all that much. The big question is whether patients taking beloranib will continue to lose weight beyond the initial 12 weeks. Zafgen is planning to start a phase 2b trial in the first half of next year. Hopefully it will test patients for longer than three months.

The other major issue is that beloranib is injected, while Qsymia, Arena's Belviq, and Contrave are all taken orally. Like Novo Nordisk's Victoza, which is also injected and will probably be primarily used in patients who need a diabetes drug anyway, the market for beloranib may be limited. Side effects, including nausea and insomnia, will also play a role in exactly who gets beloranib.

If belornaib is prescribed only for the most severely obese patients, there should be plenty of potential market for VIVUS, Arena, and Orexigen.

Time to prepare
After the phase 2b trial, Zafgen is still going to have to run a couple of phase 3 trials and the FDA may want to see year-long data for safety reasons, so patients will have to wait years for beloranib to be available commercially.

Fortunately, that gives the current obesity-drug makers a few years to get their act together; they've gotten off to a slow start so far. VIVUS' obesity drug Qsymia hasn't exactly been flying off the shelves, and Arena Pharmaceuticals' marketing partner Eisai hasn't done much better with their obesity drug Belviq. Orexigen and its marketing partner Takeda get a free pass for Orexigen, but that's only because Contrave isn't on the market yet.

I continue to think there's a potential market for obesity drugs, but the drugmakers are going to have to convince doctors that the benefits justify the side effects and secure insurance coverage so patients can afford to take them.