Adventrx Pharmaceuticals: Anticipation Building for FDA's September Decision

| About: Mast Therapeutics, (MSTX)

Yesterday, ADVENTRX Pharmaceuticals Inc (ANX) stock rose more than 12% as the anticipation began to build for the company’s 9/1 PDUFA date for Exelbine (ANX-530) for non-small cell lung cancer. The catalyst for yesterday’s rise was positive broker commentary.

ANX-530 is the company’s proprietary emulsion formulation of vinorelbine. Vinorelbine is a vesicant and venous irritant, and these adverse effects can limit its tolerability. ANX-530 was designed to be bioequivalent to the reference drug while reducing the incidence and severity of vein irritation associated with intravenous delivery of the drug. In a clinical bioequivalence study, ANX-530 and the reference drug were determined to be bioequivalent.

For some background, on Nov. 11, 2007, Adventrx announced that ANX-530 met its primary endpoint. Pharmacokinetic equivalence, the primary endpoint of the study, was observed between ANX-530 and Navelbine, the reference product, in patients with advanced cancer potentially sensitive to vinorelbine. Equivalence was demonstrated by a statistical comparison of both the areas under the curve and maximum plasma concentrations. On Jan. 14, 2008, the company announced the safety results from the study and said that ANX-530 demonstrated a statistically significant reduction in injection site reactions when compared with Navelbine (p<0.05). The incidence of injection site reactions attributed to Navelbine was consistent with its product label. Furthermore, ANX-530 was determined to be safe and well-tolerated with no significant differences observed in any other safety parameters.

The company originally filed the Exelbine NDA on Dec. 30, 2009. However, on March 1, 2010, Adventrx announced that it received a refuse to file letter from the FDA regarding its New Drug Application (NDA) for ANX-530. The FDA indicated that the data included in the initial submission from the intended commercial manufacturing site was insufficient to support a commercially-viable expiration dating period. FDA identified only the one chemistry, manufacturing and controls reason for the refusal to file. The company added that it expected that the FDA will require additional site-specific stability data to accept its application.

On April 27, 2010, Adventrx said that based on information received from the FDA, the company planned to resubmit its NDA for ANX-530 (vinorelbine injectable emulsion), or Exelbine, in 4Q10. The CEO said that the studies that will generate the stability data from its intended commercial manufacturing site that the FDA wishes to see are ongoing. The company then proceeded to announce 6, 9, and 12 months stability data and the data were all consistent and said it would file the NDA as originally planned. On Nov. 3, 2010, Adventrx submitted the Exelbine NDA. On Jan. 19, 2011, the FDA set the PDUFA date of Sept. 1, 2011, for the product candidate.

The company has two other late-stage products that it is focusing on developing. The first, ANX-188 for sickle cell disease, was acquired as part of the company’s acquisition of Synthrx this year. Research has demonstrated that ANX-188 adheres to hydrophobic surfaces that develop when cells are damaged and restores normal hydrated surfaces, while having little or no activity in normal, healthy tissues. Adventrx is currently planning to meet with the FDA to reach agreement on a phase 3 clinical trial protocol for ANX-188.

The other product candidate is ANX-514. ANX-514 is a novel emulsion formulation of the chemotherapy drug docetaxel, a formulation of which is marketed under the brand name Taxotere. It is formulated without polysorbate 80 or other detergents and is being developed to reduce the incidence and severity of side effects associated with detergents, such as hypersensitivity reactions. Adventrx met with the FDA in February 2011. The FDA indicated that a randomized safety study comparing ANX-514 and Taxotere would be required in an appropriate patient population to support approval of ANX-514. The study would be primarily descriptive but with a sample size sufficient to demonstrate a comparable safety profile. The FDA recommended that the study also collect data on response rate and duration of response. The company currently is developing a study protocol for submission to the FDA and intends to continue discussions with the FDA regarding the phase 3 study and other requirements for approval of ANX-514.

The financials are in decent shape. The company had over $46 million in cash at the end of last quarter. The cash position received a boost earlier this year after Adventrx raised $22.5 million. The company has no revenue and reported a loss of $3.0 million in Q1.

Disclosure: I have no positions in any stocks mentioned, and no plans to initiate any positions within the next 72 hours.