Immunovaccine Announces the Publication of DPX-0907 Preclinical Study

Study shows the DepoVax(TM) platform provides a superior immune response against cancer antigens

HALIFAX, NOVA SCOTIA -- (MARKET WIRE) -- 04/05/10 -- Immunovaccine Inc. (TSX VENTURE: IMV), a clinical stage vaccine development company, announced today the publication of data from a preclinical study with its candidate cancer vaccine, DPX-0907, in human class I MHC transgenic mice. The study compares Immunovaccine's novel DepoVax™ vaccine platform to a vaccine formulation commonly used to deliver peptide antigens in the clinic today. The study shows that the company's DepoVax™ platform promotes antigen specific immune responses, however, unlike the control vaccine, the DepoVax™ formulation does not induce problematic immune regulatory responses.

The paper entitled, "A Novel Breast or Ovarian Cancer Peptide Vaccine Platform That Promotes Specific Type-1 but not Treg or Tr1-type Responses" is published in the April 2010 issue of the Journal of Immunology, Volume 33, Number 3.

"The results of this study, indicate that our DepoVax™ vaccine platform may be able to improve the delivery and performance of cancer vaccines, by tipping the scales in favor of an active and uninhibited immune response following vaccination. If successful, such a platform may help potentiate other cancer immunotherapies," remarked Dr. Marc Mansour, vice president of R&D at Immunovaccine.

The immune system has two paradoxical roles in cancer; the first, an adaptive immune response, such as a T-cell response, capable of attacking tumor cells, and the second, a regulatory or pro-tumor response that favors tumor progression. Regulatory T cells have been shown to accumulate at the site of the tumor, creating an immunosuppressive tumor environment that can ward off anti-tumor Type-1 CD8+T-cell responses. Potent vaccines that are injected repeatedly can also induce regulatory mechanisms that counteract the desired effect of the vaccine. This poses a serious problem as most therapeutic cancer vaccines are administered repeatedly to avert the threat of resumed tumor growth after surgical removal or chemotherapy.

The major challenges in designing an effective peptide-based vaccine to treat cancer is enhancing the immunogenicity of chosen peptides and overcoming tumor induced immune suppression. To have a fighting chance at producing more prolonged cellular immune responses that can affect tumor cells, a vaccine must first activate the immune system against the targeted antigens without activating or amplifying antigen-specific regulatory mechanisms. The DepoVax™ formulation used in DPX-0907 was capable of achieving this in the preclinical mouse model.

Transgenic mice vaccinated with DPX-0907 exhibited more than double the number of peptide-specific (CD8+IFN-g+), T-cells when compared with the control oil emulsion-based vaccine. In fact, mice that received follow-up booster immunizations of DPX-0907 maintained the high levels of interferon gamma (a cytokine indicative of vaccine-induced T cell immunity), whereas the mice immunized with the control vaccine displayed significantly lower levels of the T cell activation cytokine. This study suggests that the novel DepoVax delivery platform may provide better sustained antigen-specific immune responses compared to other peptide vaccine delivery methods. Interestingly, DPX-0907 formulation also provided a safer vaccine alternative to the control emulsion vaccine.

DPX-0907 is an oil-depot vaccine formulation that is currently being tested in a phase 1 clinical trial for the therapy of breast, ovarian or prostate cancer patients. DPX-0907 uses lyophilized (freeze-dried) liposomes, containing seven antigens and an adjuvant, and an oil delivery. The seven peptide antigens were identified from the surface of breast and ovarian tumor cell lines, but were not found on normal cells. The antigens were selected on the basis of their association with pathways essential for tumor growth and survival. Given DPX-0907's favorable safety profile, its ability to differentially promote type-1 versus Treg-type immunity, and its lyophilized format for enhanced shelf-life and stability, the DepoVax™ technology appears to be a promising platform for the development of the next generation of therapeutic/prophylactic vaccines for cancer and infectious diseases.

About Breast and Ovarian Cancers

Breast cancer is the second leading cause of cancer-related death among American women, and ovarian cancer is the eighth most common cancer in women, and the fifth leading cause of female cancer death, according to the National Cancer Institute.

Future novel cancer immunotherapy provides a viable means to manage these metastatic diseases. In particular, synthetic peptide-based vaccines, capable of inducing specific T-cell immune response will potentially be effective strategies for treatment.

Immunovaccine Inc. (TSX VENTURE: IMV) is a clinical stage vaccine development company focused on the commercialization of its patented DepoVax™ vaccine delivery technology and product candidates. The company continues to strengthen its vaccine pipeline through licensing and strategic partnerships to develop therapeutic cancer and infectious disease vaccines.

This press release contains forward-looking information under applicable securities law. All information that addresses activities or developments that we expect to occur in the future is forward-looking information. Forward-looking statements are based on the estimates and opinions of management on the date the statements are made. However, they should not be regarded as a representation that any of the plans will be achieved. Actual results may differ materially from those set forth in this press release due to risks affecting the Company, including access to capital, the successful completion of clinical trials and receipt of all regulatory approvals. Immunovaccine Inc. assumes no responsibility to update forward-looking statements in this press release.

Neither TSX Venture Exchange nor its Regulation Services Provider (as that term is defined in the policies of the TSX Venture Exchange) accepts responsibility for the adequacy or accuracy of this release.

Immunovaccine Inc.
Dr. Marc Mansour
Vice President R&D
(902) 492-1819

Immunovaccine Inc.
Jennifer Ayotte
Director Communications
(902) 492-1819

Tiberend Strategic Advisors, Inc.
Andrew Mielach
(212) 827-0020