Vical Incorporated announced the issuance of European Patent EP1587816, which extends coverage for TransVax, the company's first-in-class therapeutic DNA vaccine designed to prevent reactivation of latent cytomegalovirus (CMV) or introduction of CMV through donor cells or tissues in transplant recipients.

TransVax encodes the CMV glycoprotein B (gB) and phosphoprotein 65 (pp65) antigens, and is formulated with a poloxamer designed to enhance primarily a cellular immune response. Vical's TransVax vaccine has orphan drug designation for transplant patients. In September 2010, Vical announced encouraging results from a completed phase 2 trial of the TransVax vaccine in patients undergoing haematopoietic stem cell transplants. The company is currently in discussions with regulatory authorities to confirm the design of a planned Phase 3 trial which is expected to begin in the second half of 2011.

Past development by others of protein-based prophylactic CMV vaccines has focused on antibody-mediated immune responses against the CMV gB antigen, which has achieved up to 50% protective efficacy. The new '816 patent covers DNA vaccines containing codon-optimized versions of genes encoding gB and CMV pp65 antigens, formulated with the CRL-1005 poloxamer in-licensed by Vical. It adds to Vical's family of patents in key geographic regions based on the company's discovery that administering genetic sequences such as DNA or RNA into the body, without the use of viral delivery vehicles, may cause expression of the proteins encoded by the genetic sequences. Vical has additional issued patents covering enhancements, manufacturing, and specific applications of its core technology.

CMV is a herpes virus that infects more than half of all adults in the United States by age 40, and is even more widespread in developing countries. While a healthy immune system typically protects an infected person against CMV disease, it rarely succeeds in eliminating the infection, and those whose immune systems are not fully functional are at high risk of CMV reactivation, potentially leading to severe illness or death. Those at greatest risk include transplant patients and infants born to mothers who first become infected during pregnancy. Vical is pursuing two different vaccine approaches for these distinct market segments.

CMV affects 30% to 60% of patients undergoing transplant procedures, causing transplant rejection, serious illness and even death if untreated. Expensive and toxic antiviral drug therapy is used to control the disease, but does not eliminate the infection. There is no approved vaccine against CMV. Protein-based vaccines that predominantly result in antibody responses to CMV may have limited effectiveness in transplant patients. Live, attenuated vaccines can induce both antibody and cellular immune responses, but pose a potential safety concern, particularly for immunocompromised patients, of causing the disease they are intended to prevent.

Vical researches and develops biopharmaceutical products based on its patented DNA delivery technologies for the prevention and treatment of serious or life-threatening diseases. Potential applications of the company's DNA delivery technology include DNA vaccines for infectious diseases or cancer, in which the expressed protein is an immunogen; cancer immunotherapeutics, in which the expressed protein is an immune system stimulant; and cardiovascular therapies, in which the expressed protein is an angiogenic growth factor.