Vical Incorporated announced the issuance of US Patent No. 7,888,112 covering DNA vaccines for cytomegalovirus (CMV) containing specific gene sequences and formulated with Vical's Vaxfectin adjuvant.
Past development by others of protein-based prophylactic CMV vaccines has focused on antibody-mediated immune responses against the CMV glycoprotein B (gB) antigen, which has achieved up to 50 per cent protective efficacy. The new '112 patent covers DNA vaccines containing codon-optimized versions of genes encoding gB and CMV phosphoprotein 65 (pp65) antigens, formulated with Vical's Vaxfectin adjuvant. It adds to Vical's family of patents in the United States and other key 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 the composition and use of the Vaxfectin adjuvant.
Mothers who are infected with CMV during pregnancy can transmit the virus to the foetus, where it affects the development of the central nervous system. Congenital CMV is the leading infectious disease cause of birth defects in the United States, similar to rubella in the '40s and '50s before an effective vaccine was available. CMV-infected infants can be affected by blindness, deafness and mental retardation, and these consequences are frequently undiagnosed until the child reaches several years of age. Widespread vaccination of adolescent females has the potential to significantly reduce or even eliminate congenital CMV over time, and this market segment offers a significant commercial vaccine target. The successful launch of Merck's Gardasil vaccine for the prevention of human papillomavirus (HPV), a primary cause of cervical cancer, has demonstrated the size and receptivity of the adolescent female vaccine market.
Targeting prevention of infection in females of child-bearing potential, Vical is developing CyMVectin, a prophylactic DNA vaccine encoding the CMV gB and pp65 antigens and formulated with Vical's Vaxfectin adjuvant designed to enhance both antibody and T-cell responses. The US Food and Drug Administration (FDA) has allowed the company's Investigational New Drug (IND) application for a phase 1 trial of the CyMVectin vaccine, and Vical is exploring collaborative opportunities for further development and commercialization.
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.
For transplant patients, Vical is developing TransVax, a therapeutic DNA vaccine encoding the CMV gB and the pp65 antigens, and 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 hematopoietic stem cell transplants. The company is currently meeting with regulatory authorities to confirm the design of a planned Phase 3 trial which is expected to begin in the second half of 2011.
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.
Vical researches and develops biopharmaceutical products based on its patented DNA delivery technologies for the prevention and treatment of serious or life-threatening diseases.