BioSante Pharmaceuticals Announces Positive Results of CAP Adjuvant Study in CDC Collaboration.

Business Editors/Health/Medical Writers

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LINCOLNSHIRE, Ill.--(BUSINESS WIRE)--April 29, 2004

BioSante Pharmaceuticals, Inc. (Amex:BPA) today announced that a comparative preclinical study demonstrated its calcium phosphate (CAP) nanotechnology-based vaccine adjuvant, BioVant(TM), may be more effective than aluminum salt derivatives (alum), the only adjuvant currently approved by the Food and Drug Administration (FDA). The study was conducted in collaboration with the U.S. Centers for Disease Control and Prevention (CDC) in a previously unannounced BioSante collaboration. The results will be presented today at the World Vaccine Congress in Montreal.

"These positive study results contribute to the growing body of evidence that BioVant is an effective alternative to alum for the enhancement of immune system response to vaccines," said Stephen M. Simes, president and chief executive officer of BioSante. "Moreover, in contrast to non-biodegradable, non-biocompatible alum, our CAP nanoparticles are easily degraded in the body with no ill effects, and have been shown in an FDA-approved trial to be 'safe and nontoxic' to humans."

In addition to a BioVant formulation that promotes a Th1 (antiviral) immune response, BioSante researchers recently developed a formulation of the adjuvant that produces a Th2 (antibacterial) response. Both formulations were tested in this study, along with alum.

The study's objective was to assess the comparative efficacy of various vaccine adjuvants in eliciting cellular and humoral immune responses to a recombinant circumsporozoite protein (CSP) from the infectious (sporozoite) stage of malaria contracted from biting mosquitoes. Mice were injected either twice or three times, each inoculation 15 days apart, with CSP alone (controls) or with vaccine formulations containing aluminum hydroxide (alum), CAP-Th1 or CAP-Th2 adjuvants. The mice were monitored and their blood was tested at three different times to determine antibody levels.

After three inoculations with the respective adjuvanted malaria vaccine formulations, CAP-Th2 produced an immune response four times greater than that of alum.

"This study shows that BioVant is a non-aluminum adjuvant that enhances pathogen-specific immune responses of comparable or greater potency compared to the only adjuvant currently approved for use in humans, namely the aluminum adjuvant," said Dr. Steve J. Bell, vice president of research and preclinical development for BioSante. "We are very encouraged by these results and will continue to develop this potentially vital new weapon in the fight against infectious disease."

An adjuvant is a substance that, when added to a vaccine, enhances the vaccine's effect by stimulating an immune system response. While aluminum salt derivatives, such as alum, are the only adjuvants currently approved by the FDA, alum has been associated with adverse reactions such as irritation and inflammation of the injection site, and may also result in an allergic reaction.

In contrast, BioVant is composed of specially formulated calcium phosphate, a naturally occurring compound similar to that found in teeth and bones. In multiple studies, BioVant has been shown not to cause inflammation at the injection site, and no allergic response has been observed.

Another drawback of alum is the type of immune reaction it typically triggers. Alum primarily promotes a particular subset of T-helper cells, known as Th2 cells, which target extracellular bacterial infections but tend not to be optimal for fighting viral infections. BioVant, on the other hand, elicits a biased Th1 cell response with concurrent Th2 response, the combination of which activates T lymphocytes that destroy virally infected cells and which promotes antibody immunity -- or can be adjusted to produce either type of response. In this way, the two adjuvants may serve as complements to each other.

"We believe CAP, in the form of BioVant, shows potential to be an important adjuvant for the next generation of vaccines against both viral and bacterial infections," Simes said. "BioSante and several commercial and military partners are now conducting additional pre-clinical studies of BioVant in several potential vaccines, and the company is pursuing additional licenses for further development of CAP in all areas."

BioSante has licensed its BioVant adjuvant to Corixa Corporation on a nonexclusive basis for use in a variety of vaccines. The company is also working with the U.S. Navy and Army and the U.S. Department of Defense to develop vaccines against malaria, anthrax, ricin, staph and the bubonic plague.

About BioSante Pharmaceuticals, Inc.

BioSante is developing a pipeline of hormone therapy products to treat both men and women. The company also is developing its calcium phosphate nanotechnology (CAP) for novel vaccines, including biodefense vaccines such as anthrax and ricin, and drug delivery systems. Additional information is available online at www.biosantepharma.com.

This news release contains forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995. The statements regarding BioSante contained in this press release that are not historical in nature, particularly those that utilize terminology such as "may," "will," "should," "likely," "expects," "anticipates," "estimates," "believes" or "plans," or comparable terminology, are forward-looking statements. Forward-looking statements are based on current expectations and assumptions, and entail various risks and uncertainties that could cause actual results to differ materially from those expressed in such forward-looking statements. Important factors known to BioSante that cause actual results to differ materially from those expressed in such forward-looking statements are the difficulty of developing pharmaceutical products and especially of new vaccines, obtaining regulatory and other approvals and achieving market acceptance, and other factors identified and discussed from time to time in BioSante's filings with the Securities and Exchange Commission, including those factors discussed on pages 18 to 25 of BioSante's Form 10-KSB, which discussion also is incorporated herein by reference. The information contained in this press release does not necessarily reflect the position or the policy of the U.S. Government and no official endorsement should be inferred."