BOSTON (TheStreet) --This week's Biotech Stock Mailbag is for readers who use email instead of Twitter: Check out my the Twitter-centric Mailbags from earlier this week here and here.

Andy S. writes, "My question to you is in response to Dacogen and its relation to sapacitabine developed by Cyclacel Pharmaceuticals (CYCC - Get Report). Could you please explain whether Dacogen's approval/disapproval will impact sapacitabine's Phase III trial? Thanks!"

Some background: On Feb. 9, an FDA advisory panel voted not to recommend an expanded approval for Astex Pharmaceutical's ( ASTX) cancer drug Dacogen to cover treatment for elderly adults with acute myelogenous leukemia (AML). The FDA's decision date for Dacogen in AML is Tuesday, March 6, but given the negative panel vote, an approval isn't likely.

If FDA doesn't approve Dacogen for AML, this poses a problem for Cyclacel Pharmaceuticals, which is testing its drug sapacitabine in combination with Dacogen as a potential new AML therapy. A phase III study comparing sapacitabine plus Dacogen versus Dacogen is ongoing.

The short answer is "no" -- Cyclacel's phase III study should remain unaffected if FDA rejects Dacogen in AML. I asked Michael Becker of MD Becker Partners and a paid consultant to Cyclacel for help explaining why:

1. The sapacitabine phase III study was designed with a Special Protocol Assessment in which FDA agreed to the use of Dacogen despite the drug not being approved for AML. Dacogen is approved as a treatment for myelodysplastic syndrome (MDS), another blood-related cancer.

2. In its briefing documents for Dacogen, FDA notes that "clinical trial" is a commonly accepted treatment option for elderly AML patients. In other words, says Becker, unapproved drugs can be used as control drugs in a phase III trial of AML.

3. Even if FDA rejects Dacogen, it's still an available therapy for AML in the U.S. (where Cyclacel is conducting the sapacitabine study) and insurers pay for it, says Becker.

4. If FDA approves Dacogen, then Cyclacel is also fine, except, of course, the phase III study still has to demonstrate that sapacitabine plus Dacogen is better than Dacogen alone.

Chris L. asks, "What's your take on the top brass at Vivus (VVUS - Get Report) dumping their shares in the past week?"

Smart. Opportunistic. Expected.

If you own stock or options with a cost basis of $4 per share and their value rises suddenly to $22 per share, wouldn't you be selling too?

I hope so.

I'm not sure if this matters, but the investors who gobbled up shares of Vivus in this week's financing didn't seem to be bothered by the insider selling.

The bigger issue is Qnexa's peak sales potential. I'm seeing some silly estimates thrown around equating the weight-loss drug to Lipitor. C'mon, Qnexa is not the next Lipitor, which delivered $11 billion in annual sales to Pfizer ( PFE) at the drug's peak. As my friend and fellow biotech/drug scribe Matt Herper from Forbes pointed out recently, no obesity drug has ever generated more than $1 billion in annual sales.

Qnexa may be the first drug to clear this hurdle, but, then, it may not because, as Herper explains, people who are forced to rely on a pill to lose weight are flakes. Lots of these people may try Qnexa but far fewer will stick with the drug for a year or two, if historical compliance and dropout trends are to be believed.

To Herper's view, I'd add that Qnexa, if approved only for obesity, is not likely to be reimbursed by insurance companies. That means patients are going to pay $90 or more every month out of their own pockets to stay on the drug. Hint: You can join a very nice gym for the same money.

Lastly, topiramate (one of the two active drug components in Qnexa) makes people's brain go fuzzy -- memory loss, difficulty with concentration and attention, even language difficulties. In the Qnexa clinical trials, 5.6% and 7.8% of patients on the mid- and high-dose, respectively, experienced cognitive-related adverse events. These side effects aren't likely serious enough to derail Qnexa's approval but they might definitely hurt the drug commercially.

J.T. writes, "First of all, congratulations on your last two calls on Vivus and Chelsea Therapeutics (CHTP). You were spot on. Although I have disagreed with several of your articles in the past, your assessment on both companies was fair and correct. Staying in the "fair" mode, I can sometimes be overly critical, so I offer you kudos when you're right. (By the way, I was wrong on both of those.)"

Thanks, J.T. You don't hear many people saying "I was wrong" these days. That's too bad. There is nothing wrong with being wrong. We all make mistakes. What's important is accountability -- acknowledging your errors, learning from them and congratulating those who get it right. I try hard to play by those rules, and I respect folks like J.T. who do the same.

JM asks, "Question regarding Celldex Therapeutics (CLDX - Get Report): Stock is pretty much flat for more than a year, then in January over the course of maybe four weeks it practically doubles in value. Then company sells more shares, and stock promptly falls back to where it was before January. What gives? Is this stock manipulation?"

No, it's just biotech. Remember the old biotech saw: You raise money when you can, not when you need. Celldex shares were up about 80% to 90% year to date so the company raised money opportunistically. It might suck for you if you were unlucky to buy Celldex at its recent high but the company is just playing by the biotech rulebook.

Celldex is still up 38% for the year -- that's damn good. More important for Celldex and its shareholders will be results from the phase II study of CDX-011 in breast cancer expected this spring at the American Society of Clinical Oncology's annual meeting. I don't know if the CDX-011 study will be a success, but the company's decision to raise money last month is not a negative tell, in my opinion.

Ken B. doesn't like my FDA Drug Approval Contest: "Adam F., to quote your asinine boss, 'YOU KNOW NOTHING' and your silly contest is a meaningless and worthless exercise. Thanks for being such a reliable reverse indicator!"

Haters gonna hate.

Abe L. takes umbrage over my concerns about Exelixis' ( EXEL - Get Report) prostate cancer drug cabozantinib:

"I will definitely be e-mailing a copy of your article today and asking the SEC to check and see what your options positions are today. Nothing but a hacket sp job on Exelixis and you know it. The SEC is worthless but guys like you are pathetic."

I wonder if there's a person at the SEC who fields these emails and says to himself (or herself), "Oh, Adam must have written another Mailbag today." If so, I apologize for my fans. They can get a bit rambunctious.

Ted B. asks, "What is your vote on Surfaxin from Discovery Labs (DSCO) and why?"

I say FDA approves Surfaxin on Tuesday. Why? The little-known FDA Mercy Rule. It's inconceivable that a company can screw up so badly that its drug is rejected five times in a row. Therefore, Surfaxin will be approved.

If you want to read a contrarian take on Discovery and Surfaxin, Joseph Lee of argues that FDA will reject the drug.

--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.