PANVAC for breast, ovarian cancer shows early promise
Baku, December 12 (AZERTAC). A study of 26 women with breast and ovarian cancer found that the PANVAC vaccine helped the immune system recognize and destroy tumor cells. The trial was conducted at the Laboratory of Tumor Immunology and Biology at the National Cancer Institute, with results published in the journal Clinical Cancer Research. Of the 26 women tested, all had exhausted other treatment options and had cancer that spread to other parts of the body. Of the 12 patients with breast cancer, PANVAC delayed disease progression 2.5 months, with a median overall survival of 13.7 months. Four patients had stable disease, and one woman`s cancer disappeared. Of the 14 patients in the ovarian cancer group, the vaccine delayed progression two months with a median overall survival of 15 months. "With this vaccine, we can clearly generate immune responses that lead to clinical responses in some patients," said lead researcher Dr. James Gulley in a release. "The sustained benefit seen in some patients in this study underscores the potential for therapeutic vaccines to impact clinical outcomes without toxicity. However, more studies in the appropriate patient populations are required to adequately assess efficacy." PANVAC is a cancer vaccine therapy delivered through two viral vectors--recombinant vaccinia and recombinant fowlpox--which are given sequentially. Both vectors contain transgenes for the tumor-associated antigens epithelial mucin 1 and carcinoembryonic antigen, which are altered or overexpressed in most carcinomas. The vectors also contain transgenes for three human T cell costimulatory molecules required to enhance immune response: B7.1, intracellular adhesion molecule-1 and leukocyte function-associated antigen-3. PANVAC is injected subcutaneously and processed by the body`s antigen-presenting cells. Specifically, these antigens serve as targets for the host immune system and elicit responses that results in tumor destruction. The initiation of an effective T-cell immune response to antigens requires two signals. The first one is antigen-specific via the peptide/ major histocompatibility complex and the second or “costimulatory” signal is required for cytokine production, proliferation, and other aspects of T-cell activation. The PANVAC technology employs avirulent poxviruses to present a combination of tumor-associated antigens (TAAs) and costimulatory molecules to activate T-cells and break the immune systems tolerance towards cancer cells. This is performed using recombinant poxvirus DNA vectors that encode both T-cell costimulatory molecules and TAAs. The combination of the costimulatory molecules B7.1, ICAM-1 and LFA-3, is known as TRICOM. Recombinant poxviral vaccines (vaccinia (V) and fowlpox (F) containing TRICOM have been evaluated in prime (V)/boost (F) regimens in preclinical models and in several clinical trials in patients with metastatic colorectal cancer. Additionally, PANVAC has shown promising survival results in treating patients with metastatic colorectal cancer. Furthermore, recombinant poxviral TRICOM based vaccines can also be employed for the prevention and/or therapy of colorectal cancer containing a range of other TAAs such as the T-box transcription factor Brachyury.
Other news in this section
