Development of a Pharmacodynamic Biomarker of Opioid Antagonism in Adolescents with Eating Disorders - Project Summary The overall goal of this 4-year K23 proposal is to support Dr. Stephani Stancil to become an independent investigator in the field of pharmacodynamic biomarker development to support quantitative early-stage drug development in pediatric neuropsychopharmacology, specifically eating disorder therapeutics. This proposal aligns with NIMH’s prioritization of and the National Advisory Mental Health Council workgroup recommendations for quantitative pharmacologic early-stage trials, particularly in vulnerable populations. Eating disorders (ED), including Bulimia Nervosa, Anorexia Nervosa-Binge/Purge and Binge Eating Disorder, are characterized by binge eating and purge behaviors (e.g., vomiting), typically begin in adolescence, and affect up to 5% of teens. EDs are associated with significant morbidity (e.g., malnutrition, cardiac compromise, development of substance use disorder), have the highest mortality rate of any psychiatric illness and are not responsive to current pharmacotherapy. This career development proposal will leverage Dr. Stancil’s clinical pharmacology expertise in drug exposure inquiry and expand her career focus to clinical neuropsychopharmacology to enable her to define central nervous system drug action in children and adolescents. The comprehensive career development plan (CDP) contains three training objectives: 1) neuroimaging, 2) pediatric randomized clinical trials, and 3) exposure-response modeling, to transition Dr. Stancil into a successful, independent investigator. The CDP’s structured mentoring, didactic training and experiential learning will be applied to a randomized, placebo-controlled crossover trial in adolescents with Binge/Purge ED to accomplish the following aims: Aim 1) Determine the sensitivity of a neuroimaging biomarker to reward system modulation by opioid antagonism, Aim 2) Develop an Exposure-Response Model for naltrexone. Dr. Stancil’s career development and research will take place in a highly favorable and well- suited environment that includes a tertiary academic children’s medical center, children’s research institute, joint department of pediatrics shared by two regional medical schools, an outstanding imaging center and the Frontiers CTSA. After completing this project, Dr, Stancil will have advanced the field of pharmacodynamic biomarker development in pediatric mental health and generated data to support an R01 application to establish the validity of the proposed pharmacodynamic biomarker. She will be well-positioned to become a leader in the field of pharmacodynamic biomarker development and exposure-response linkage to de-risk early-stage drug development and facilitate a precision therapeutics approach to pediatric neuropsychopharmacology.