Predictive biomarkers for fluoxetine response in adolescents and children with depression: a proteomic and metabolomic approach

Caio Henrique de Souza Ferreira Berdeville1, Osmar Henrique Della Torre2,3, Licia Carla Silva-Costa1, Bradley Joseph Smith1, Ermilo Bettio Junior2, Adriana Leandra Santoro1,4, Fernanda Crunfli1,5, Renata Cruz Soares de Azevedo2, Daniel Martins-de-Souza1,6,7

1. LNP, Laboratory of Neuroproteomics, Department of Biochemistry and Tissue Biology, University of Campinas; Campinas, SP, Brazil
2. FCM, Department of Psychiatry, School of Medical Sciences, University of Campinas; Campinas, SP, Brazil
3. PUC-Campinas, Department of Psychiatry, Medical School, Pontifical Catholic University of Campinas; Campinas, SP, Brazil
4. OCRC, Obesity and Comorbidities Research Center, University of Campinas; Campinas, SP, Brazil
5. TNU, Translational Neuropsychiatry Unit, Department of Clinical Medicine, Aarhus University; Aarhus, Denmark
6. IDOR, D’or Institute for Research and Education; Rio de Janeiro, RJ, Brazil
7. EMRC, Experimental Medicine Research Cluster, University of Campinas; Campinas, SP, Brazil

Introduction: Major depressive disorder (MDD) is characterized by depressed mood and anhedonia, affecting almost 280 million people worldwide. In children and adolescents, irritability may replace sadness as a symptom. Antidepressants are the main treatment strategy for MDD, with fluoxetine showing the highest efficacy in children. Recently, both proteomics and metabolomics have been employed to identify biomarker candidates for adults with MDD. However, the use of such tools to the biological understanding and identification of potential biomarkers of MDD and antidepressant response in children and adolescents still demands investigation. Aim: This project aims to identify the difference between molecular mechanisms associated with the response to fluoxetine in children, adolescents, and adults for the purpose of identifying biomarkers specific to early life stages. Methods: A prospective and observational cohort study is being conducted, recruiting children (7 to 11 years; n = 30), adolescents (12 to 21 years; n = 30), adults (22 to 50 years; n = 30), and their respective controls (n = 90). Blood samples are collected before and after an 8-week period of use of fluoxetine. Inclusion criteria are: (1) MDD diagnosis assessed by the Structured Clinical Interview for the DSM-5 or the Kiddie-Schedule for Affective Disorders and Schizophrenia-Present and Lifetime version, (2) total score of at least 17 in the Hamilton Depression Rating Scale, or 45 points in the CDRS-Revised for children, and (3) being antidepressant drug-naive or drug-free for at least 30 days. Exclusion criteria are (1) Any other psychiatric disorder other than MDD or MDD with anxiety symptoms, (2) Physical illness that may affect inflammation, neurological processes, or biomolecule metabolism pathways assessed by clinical history and physical examination, (3) Any medication use in the past 30 days. Regarding controlling confounding factors, the severity of anxiety symptoms will be assessed with the Hamilton Anxiety Rating Scale or the SCAS for children, suicidality with the Columbia Suicide Severity Rating Scale, food intake with a food frequency questionnaire, physical exercise level with the International Physical Activity Questionnaire, and alcohol use and smoking habits with the ASSIST scale. The plasma of the participants will be submitted to a proteomic and metabolomic evaluation based on mass spectroscopy associated with liquid chromatography. Data will be analyzed to assess differentially expressed proteins and metabolites, pathway enrichment, and interaction between molecules, evaluating the association of those features with sociodemographic, clinical, and psychopathological variables, including the response status. For this purpose Metascape, Reactome, String, David bioinformatic database, OmicScope, and Metaboanalyst will be used. A Receiver Operating Characteristic (ROC) curve will be generated, performing the acquisition of the area under the curve (AUC). Results: The project has been approved by the ethics committee and is now in the phase of patient enrollment. Conclusion: This project is expected to propose a biomarker panel capable of distinguishing fluoxetine responders from non-responders across developmental stages, enhancing diagnostic and therapeutic strategies and deepening our understanding of MDD biology.

Agradecimentos: Funding agency: São Paulo Research Foundation (Process 2019/00098-7, 2024/22955-7 and 2023/14968-9).