Mast Therapeutics, Inc. (MSTX)

[zigzagman]

re: Today's SEC Filing...

OK...I found it...Thanks!...Scroll down to the part I underlined in red...That pretty much sums it up as far as any new DILUTION goes...And this is just one of many AMENDMENTS to this particular Prospectus...Nothing really new here, or anything to worry about IMO...This is the SIXTH Supplement to the original Prospectus!...

You could've saved us a lot of time by posting a link to this in your first post on the subject...I was looking at the Yahoo Finance page for SEC Filings, and it hasn't shown up there yet...

http://finance.yahoo.com/q/sec?s=ANX

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HERE IT IS:

http://ir.adventrx.com/phoenix.zhtml?c=75414&p=IROL-secToc&TOC=aHR0cDovL2NjYm4uMTBrd2l6YXJkLmNvbS94bWwvY29udGVudHMueG1sP2lwYWdlPTY4NDI3NDQmcmVwbz10ZW5r&ListAll=1

The information in this prospectus supplement is not complete and may be changed. We may not sell these securities until the registration statement filed with the Securities and Exchange Commission is effective. This prospectus supplement is not an offer to sell these securities and it is not soliciting an offer to buy these securities in any state where the offer or sale is not permitted.

Prospectus Supplement No. 6
(to Prospectus dated October 6, 2009)
Filed pursuant to Rule 424(b)(3)
Registration Statement Nos. 333-160778
333-162361

PRELIMINARY AND SUBJECT TO COMPLETION, DATED March 18, 2010

ADVENTRX PHARMACEUTICALS, INC.

11,283 shares of 4.25660% Series D Convertible Preferred Stock
Warrants to Purchase up to 19,800,000 shares of Common Stock 79,800,000 shares of Common Stock Underlying the Convertible Preferred Stock and the Warrants

Pursuant to the prospectus dated October 6, 2009, we offered up to $11,283,000 of our 4.25660% Series D Convertible Preferred Stock, or 11,283 shares based on a stated value of $1,000 per share, and warrants to purchase up to 19,800,000 shares of our common stock. Delivery of the convertible preferred stock and warrants was made on or about October 9, 2009. Pursuant to that prospectus, as subsequently supplemented, we are also offering 79,800,000 shares of our common stock issuable upon conversion of the convertible preferred stock and exercise of the warrants. All of the convertible preferred stock has been converted into shares of our common stock and we did not receive any proceeds upon conversion of the convertible preferred stock. The warrants, which have an exercise price of $0.1468 per share, are currently exercisable and may be exercised at any time on or before October 9, 2014.

Recent Developments

We have incorporated by reference into this prospectus supplement the Annual Report on Form 10-K of ADVENTRX Pharmaceuticals, Inc. for the fiscal year ended December 31, 2009 (the “Annual Report”). This prospectus supplement should be read in conjunction with the prospectus dated October 6, 2009, prospectus supplement No. 1 filed on November 10, 2009, prospectus supplement No. 2 filed on January 4, 2010, prospectus supplement No. 3 filed on January 4, 2010, prospectus supplement No. 4 filed on February 11, 2010, and prospectus supplement No. 5 filed on March 1, 2010 (collectively, the “Prospectus”), which is to be delivered with this prospectus supplement. This prospectus supplement updates and supplements the information in the Prospectus. If there is any inconsistency between the information in the Prospectus and this prospectus supplement, you should rely on the information in this prospectus supplement.

Investing in our securities involves a high degree of risk. Before buying any of our securities, you should read the discussion of material risks of investing in our securities in “Risk Factors” beginning on page 6 of the Prospectus and beginning on page 15 of the Annual Report.

You should rely only on the information contained in the Prospectus, any free writing prospectus prepared by us or on our behalf and this prospectus supplement. We have not authorized anyone to provide you with different or additional information. If anyone provides you with different or additional information, you should not rely on it.

Our common stock is listed on the NYSE Amex under the symbol “ANX.” The last reported sale price of our common stock on the NYSE Amex on March 17, 2010 was $0.2399 per share. We do not intend to list the convertible preferred stock or warrants on any securities exchange.

Neither the Securities and Exchange Commission nor any state securities commission has approved or disapproved of these securities or determined if this prospectus supplement is truthful or complete. Any representation to the contrary is a criminal offense.

The date of this prospectus supplement is ____, 2010.