PROJECT SUMMARY/ABSTRACT
This Mentored Patient-Oriented Research Career Development Award proposal will provide didactic and
experiential training, expert mentorship, and an exceptional research environment to facilitate Dr. Caitlin
Elgarten's development as an independent clinician scientist. Dr. Elgarten's long-term career goal is to develop
strategies that use targeted measurement and manipulation of the microbiome to predict and prevent adverse
outcomes of pediatric stem cell transplant (SCT). Although SCT offers a chance for cure for more than 1,500
children each year with life-threatening disorders of the hematologic and immune systems, the success of this
treatment is limited by aberrant and/or delayed recovery of the new immune system leading to graft-versus-host
disease (GVHD), serious infection and reduced survival. In this proposal, Dr. Elgarten will leverage data from
three pediatric cohorts to characterize the disruption of the gastrointestinal tract microbiome that occurs during
SCT. She will define the microbiome features that associate with acute GVHD and peripheral immune cell
recovery, and identify the pharmacologic drivers of clinically relevant microbiome disruption. Through the
adaptation of non-linear mixed effects models for repeated measures to model the multidimensional and highly
dynamic nature of the microbiome, this study will deliver a greater understanding of the causal association of the
microbiome and immune events after SCT. In doing so, this work will lay the foundation for identification of novel
biomarkers and the rational design of interventions to improve SCT outcomes. Execution of these aims will also
provide the candidate with essential experience in conducting observational microbiome research and with
critical training in the advanced bioinformatics and statistical methods necessary to study the interaction of the
microbiome, pharmacologic exposures and clinical factors that define risk for adverse outcomes after SCT.
The candidate is a pediatric oncologist and SCT physician with formal training in pharmacoepidemiology and a
background in clinical research focused on supportive care in SCT. She aspires to bring her perspective as a
clinician and epidemiologist to the study of longitudinal microbiome change in this complex clinical scenario. Dr.
Elgarten's goals for the K23 program are: 1) conduct a patient-oriented research project that will yield clinically
meaningful results, 2) acquire bioinformatics skills for the analysis of microbiome sequencing data, and 3)
develop a platform for analysis of longitudinal microbiome data in SCT based on non-linear mixed effects models
for repeated measures. She has assembled a strong mentorship and advisory team, led by Dr. Brian Fisher, and
inclusive of national experts in microbiome-host biology, deep sequencing methods and bioinformatics,
quantitative model-based methods, and translational epidemiology. This guidance, combined with the extensive
resources available at the Children's Hospital of Philadelphia and the University of Pennsylvania, will ensure the
accomplishment of the proposed research and training goals and Dr. Elgarten's successful transition to
independent investigator.