Acute Phase Responses to Novel, Investigational Vaccines in Toxicology Studies: The Relationship Between C-Reactive Protein and Other Acute Phase Proteins.

The objective of this study was to determine the effects of investigational vaccine candidates on acute-phase proteins (APPs) as determined in GLP toxicology studies. Sixty-four GLP toxicity studies, which were submitted to the Food and Drug Administration from 2008 to 2012 in support of proposed clinical investigations, were reviewed and entered into a database. These studies employed the intramuscular route of injection and were conducted using New Zealand White rabbits. A retrospective review of these GLP toxicity studies was conducted to evaluate the changes in plasma levels of C-reactive protein (CRP), fibrinogen, and albumin as APPs following the administration of various investigational vaccines. The incidence and intensity of responses associated with acute-phase responses both positive and negative were observed to increase in animals when treated with vaccines containing more potent immunological components such as novel adjuvants that activate Toll-like receptors in the investigational vaccine products. Changes in plasma levels of CRP were prominent among these responses and provided a basis to propose a classification scheme of H, M, L, and N responding groups. These changes in plasma proteins reflect an activation of the acute-phase response and indicate increasing levels of systemic inflammation, which potentially may be correlated with important clinical adverse events.