CNTRP POSITIVE Study

The overall objective of this project is to analyze physiological factors that impact immune response and effect of immunosuppression across different pediatric age groups, to develop age-appropriate medical and health care strategies that can improve graft survival and reduce complications in a pediatric and young adult population. There are 3 primary aims of this study:

Aim 1: Develop age-appropriate calcineurin inhibitor (CNI) dosing for pediatric SOT patients: We hypothesize that physiologically-based (PB) modeling will enable personalized CNI dosing for infants, children and youth based on age, pharmacogenotype and immune maturity. Aim 1 deliverables include 1) a personalized physiologically-based CNI dosing algorithm in SOT; 2) validation of pediatric sensitive immunosuppression monitoring tools and their therapeutic targets; and 3) validation of immunologic assays for assessing age-specific immune responses. We anticipate that personalized CNI dosing will result in early attainment and maintenance of therapeutic drug concentrations, reduce the frequency of out-of-range concentrations post-transplant, improve safety and efficacy of immunosuppression, and reduce dependence on therapeutic drug monitoring to guide drug dosing. Standardized assessment of immune function may also monitor immunosuppression more reliably and eventually reduce the need for invasive monitoring like biopsies.

Aim 2: Develop risk prediction tools based on viral-host interactions that predispose young SOT and hematopoietic stem cell transplant patients to Epstein-Barr virus disorders/post-transplant lymphoproliferative disorder (EBV disorders/PTLD): We hypothesize that susceptibility to EBV disorders/PTLD is influenced by the interaction of high-risk EBV subtypes with host factors like age, immune maturation and intensity of immunosuppression. In the above context, "EBV disorders" refers to non-malignant EBV disease as well as sustained elevation of viral loads in the absence of PTLD. We will identify high-risk viral subtypes and age-related differences in host immunity that interact to increase susceptibility to EBV disorders/PTLD in young patients. Important clinical applications are: 1) knowledge of host susceptibility factors (age and immune maturation) at the time of transplant may assist choice of less intensive immunosuppression to reduce risk of developing EBV (e.g., avoidance of T cell depletion therapies, primary prevention) and promote use of EBV prophylaxis in at risk patients (secondary prevention); 2) an EBV genotype panel will be developed as a clinical tool for detecting high risk subtypes in patients with EBV. This will help identify patients exposed to EBV who should receive aggressive therapy for EBV and/or PTLD (personalized therapy). This innovative risk stratification will enable personalized immunosuppression strategies and strategies to prevent and treat EBV/PTLD.

Aim 3: Develop health care systems strategies to enhance medication adherence in adolescents and young adults: Medication adherence is determined by factors at a variety of different "levels": patient-level (patient-, condition-, and therapy-related factors), "micro"-level (social factors and interactions with the care team), "meso"-level (organization and expertise of the healthcare team and care processes), and "macro"-level (high-level healthcare systems factors, including care and medication cost coverage, and overall care environment). We hypothesize that there are significant differences in modifiable meso- and macro-level systems factors between pediatric programs, between adult programs, and between pediatric and adult programs. Furthermore, we hypothesize that modifiable meso- and macro-level systems factors are independently associated with medication adherence. This aim has two primary objectives:

Objective 1: To characterize differences between Canadian solid organ transplant programs in potentially modifiable meso- and macro-level systems factors.

Objective 2: To identify potentially modifiable meso- and macro-level factors that are determinants of adherence, adjusting for potential confounders.

Inclusion criteria

Aim 1

• Listed for or recipient of solid organ transplant
• Planned immunosuppression with oral or enteral tacrolimus post-transplant

Aim 2

• Solid organ transplant or hematopoietic stem cell transplant recipients <18 years old
• New onset primary EBV during the first year post transplant (either Donor EBV seropositive, recipient EBV seronegative (D+R-) or donor and recipient seronegative (D-R-) at time of transplant) or new onset EBV/PTLD in the first post-transplant year.
• HSCT patients who develop secondary EBV within the first post transplant year.

Aim 3

• Single organ, kidney, liver, and heart recipients that are at least 3 months post-transplant and 2 months post hospital discharge
• Intact graft function (not currently listed for re-transplant for any organ type or on dialysis
• Receiving maintenance immunosuppression