BOSTON ( TheStreet) -- Please join me at 12 p.m. ET today for the next Biotech Stock Mailbag Live Chat.

I'll answer your questions and respond to your comments in what I hope will be an informative and fun discussion about the current state of the biotech investment sector. A sign-up link to the live chat is below.

Before I get to your questions, I want to update this week's column on noteworthy biotech stock trades in the second half of 2011. Of course, I forgot to include a couple of stocks.

First, Pacira Pharmaceuticals ( PCRX) is expecting an FDA approval decision on Oct. 28 for Exparel in post-surgical pain management. Exparel is a proprietary, long-acting formulation of the painkiller bupivacaine. FDA extended the Exparel review by three months because Pacira submitted additional information.

I met with Pacira executives a couple of weeks ago and walked out confident in Exparel's approval. The three-month delay sounded much more procedural than anything worrisome.

Second, I failed to include the expected results from a phase III study of Biodelivery Sciences' ( BDSI) BEMA buprenorphine in the third quarter. BEMA buprenorphine is a thin, dissolvable film placed inside the cheek that contains the painkiller buprenorphine.

To your questions: Paul K. asks, "What the bleep is going on with Adventrx Pharmaceuticals (ANX)? The stock goes up every day."

Let's do some calculations to illustrate why Adventrx is overvalued (perhaps wildly so) on a fundamental basis. Yes, I know, the stock is a trader's chew toy at the moment, and fundamentals don't matter, but at some point, they will.

First, I'm going to assume that exelbine, Adventrx's reformulation of the lung cancer drug vinorelbine, is approved on Sept. 1. I won't even risk-adjust for the possibility of a rejection. I'll also assume that Adventrx retains 100% of exelbine's sales -- that means no partner, no shared revenue.

With exelbine ready for launch, let's figure out the commercial opportunity. A logical place to start, of course, would be U.S. sales of vinorelbine since Adventrx's marketing strategy will be to convince doctors to switch from vinorelbine to exelbine.

Here's where the story gets dicey for Adventrx: U.S. sales of vinorelbine totaled $7 million over the past 12 months (June 2010 through May 2011), according to IMS Health. For calendar year 2010, vinorelbine sales totaled $7.6 million, according to IMS Health.

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