Biomarkers, objects that indicate something more complex and hard to measure, can be used to diagnose and/or predict diseases. In randomized HIV vaccine clinical trials, a certain immune response (the biomarker) is measured post randomization and the question is whether the vaccine’s effect on those immune responses can predict the vaccine’s effect in preventing HIV infection. Those immune responses, also known as surrogate markers, can be used to guide the development of efficacious vaccines. For more than a decade, the HVTN and SCHARP have been dedicated to ending the HIV pandemic with a successful vaccine.
“We use statistical methods to identify and develop biomarkers that will be useful in prevention and control of diseases such as infectious diseases and cancer,” said Dr. Ying Huang, associate member of VIDD, who hopes to identify biomarkers that correlate with vaccine efficacy against HIV acquisition.
While the recent RV144 clinical trial resulted in partial efficacy, it provided a wealth of information for follow-up studies to uncover potential mechanisms of protection. The presence of two types of IgG antibodies and absence of one IgA antibody were associated with reduced acquisition of HIV in vaccinated subjects compared to those who received placebo. These biomarkers are a huge step in designing even better vaccines to improve efficacy. However, because the human immune system and HIV pathogenesis are so complex, designing an efficacious vaccine is anything but simple.
“We now know of many biomarkers for numerous immune responses: how do we best select them?” Huang continued, “How do we combine all this high dimensional information to develop rules that can allow us to predict risk of HIV?”