STP Town Hall Discussion on the Use of Virtual Control Groups in Nonclinical Toxicity Studies

The 2025 Town Hall meeting of the Society of Toxicologic Pathology (STP) discussed virtual control groups (VCG) in nonclinical toxicity testing, which are being pursued by multiple organizations to reduce animal use in product development. The current VCG literature infrequently reflects the toxicologic pathology perspective. Audience members noted that concurrent control groups (CCG) are the gold standard for toxicity studies, essential for replenishing the historical control data (HCD) from which VCG are generated. The utility of VCG is context-dependent: acceptable when test article (TA)-related effects are easily separated from background findings but likely unsuitable where subtle findings must be distinguished. Global regulatory acceptance is of paramount concern in trying to shift from CCG to partly or wholly relying on VCG. Alternative approaches to reduce animal use include eliminating studies that are a common regulatory expectation but lack scientific justification, obtaining early regulatory agreement that single-species testing is sufficient, and altering study designs to reduce group numbers, sharing CCG, or blending CCG and VCG. The most effective way for toxicologic pathologists to influence this debate is to dispassionately consider opportunities and challenges of VCG related to pathology diagnoses and interpretations and communicate this perspective clearly to the broader (non-pathologist) scientific community.