BriaCell Therapeutics Corp. (TSXV: BCT.V) is one of my favorite under-the-radar micro-cap immuno-oncology stories. The company is developing BriaVax™, a proprietary allogeneic whole tumor cell vaccine for the treatment of late-stage breast cancer. Management is preparing to initiate a Phase I/II clinical study with BriaVax in the fourth quarter 2016. The company is currently completing manufacturing of the vaccine for the clinical study.BriaCell has announced some positive incremental news over the past few months since I first started following the story about a year ago. For instance, BriaCell recently appointed NY-based RK Equity Advisors LLC and TrueNorth Lifesciences LLC for the provision of corporate advisory services. Pursuant to the Agreement, RK and TruthNorth will assist BriaCell in engaging select members of the international investment community, with a focus on increasing awareness of BriaCell and its unique growth strategy, as well as assisting with the commercialization of its product and other market opportunities.The start of the Phase I/II clinical study initiates a meaningful catalyst for the shares. And given that BriaCell is now actively out and talking with investors, as well as engaging with advisory and investor relations firms to increase awareness, I thought it made sense for me to do a quick review of the story and highlight why I'm a fan of the company.Quick Refresher on BriaVaxBriaVax™ is a proprietary allogeneic whole tumor cell vaccine isolated from a chest wall lesion of a 39-year-old woman with metastatic breast cancer. The irradiated cells are ER/PR negative and overexpress HER-2/neu, a clinically validated target of effective monoclonal antibody therapeutics. BriaVax has been genetically engineered to release sargramostim (granulocyte macrophage - colony-stimulating factor [GM-CSF]) for up-regulation of professional antigen-presenting cells. GM-CSF has been shown to be the most potent immunostimulatory secreted molecule for inducing tumor immunity (1) and is believed to provide an antitumor effect that prolongs survival and disease-free survival in subjects with stage III and IV melanoma (2) and metastatic non-small cell lung cancer (3). Also, part of the treatment regimen is the addition of low-dose cyclophosphamide (CY) 2-3 days prior to inoculation to down-regulate the activity of regulatory T cells and the use of interferon (IFN) alpha to boost differentiation of dendritic cells.Treatment with BriaVax is the result of decades of clinical investigation and research into therapeutic cancer vaccines and the use of an allogeneic whole cell breast tumor line that overexpresses a clinically validated tumor antigen. The cells have been genetically engineered to secrete GM-CSF, which has multiple effects on the tumor-immune response equilibrium, including activating dendritic cell recruitment and maturation. The protocol employs a novel use of CY to take the "foot off the brake" with respect to regulatory T cell response and then follows with a local injection of IFN-alpha to "step on the gas" and evoke prolonged immune response.- BriaVax Mechanism of Action - BriaVax is believed to work by increasing expression of CD40 Ligand (CD40L), a costimulatory protein found on antigen presenting cells, such as T cell, B cell, and natural killer (NK) cells, that is required for their activation (4). Activation of CD40L has a variety of downstream effects, including dendritic cell maturation and an increase in serum levels of CD4+, CD8+, and NK cells known for their anti-tumor activities (5). BriaVax has shown that CD40L levels increase following administration of BriaVax, with one subject demonstrating tumor regression. - Predictors of Response - BriaCell believes that they have identified a gene signature predictive of response to BriaVax. For example, following the successful completion of the second Phase I study (n=4) (6), the scientists at BriaCell observed potentially prolonged overall survival among three of the four patients (median OS: ~35 months); in addition, one patient, with an OS of 33.7 months, demonstrated clinically significant (>90%) tumor) regression. Focusing more closely on these patients, BriaCell conducted a molecular analysis of both the BriaVax cell line and blood cells obtained from the Phase I patients. This "gene signature" analysis informed the company about a putative BriaVax mechanism of action and paved the way for the development of a potential companion diagnostic for both patient selection as well as monitoring during human clinical trials.The basic findings, which were presented at AACR in April 2016 (Poster #2369), show that BriaVax expresses several genes known to encode tumor-associated antigens, such as PRAME, a Cancer/Testis Antigen (CTA), which trigger immune stimulatory roles and activation of tumor-specific T cells via mechanisms of direct antigen presentation, cross-presentation, and/or cross-dressing. Simply, BriaVax stimulates both a cell-mediated and a humoral immune response, which is believed to result in robust clinical response to the vaccine. More about this topic can be found in my article from April 2016.The Planned Phase I/II Program