# Microsampling Assays for Immunosuppressive Drugs in Children

> **NIH NIH R21** · CHILDREN'S HOSP OF PHILADELPHIA · 2021 · $263,353

## Abstract

PROJECT SUMMARY
Immunosuppressive therapy is the foundation of successful long-term outcomes after solid organ and bone
marrow/stem cell transplants and as a treatment for various auto-inflammatory conditions, including rheumatoid
arthritis, eczema, psoriasis, Crohn's disease, and nephrotic syndrome in adults and children. The optimal blood
concentrations of these drugs are critical to minimize toxicity and to prevent rejection in transplant recipients.
These drugs require frequent and often life-long therapeutic drug monitoring (TDM) to ensure that dosing
maintains the optimal therapeutic concentrations. Current TDM (clinical standard) used for the dosing guidance
of cyclosporine A (CYA), tacrolimus (TAC), and sirolimus (SIR) are derived from whole blood immunoassays or
liquid chromatography-tandem mass spectrometry (LC-MS/MS) assays. This requires immunosuppressed
individuals to go to outpatient laboratories for phlebotomy, potentially increasing their risk of acquiring infections.
The development of an easy-to-use, small volume, blood sampling approach can facilitate home sampling and
reduce the burden on pediatric patients and their families. Current TDM requires 0.5 to 1.0 mL of whole blood,
typically via phlebotomy. Volumetric absorptive microsampling (VAMS) with Mitra devices or Tasso-M20 devices
allows for the collection of a fixed small volume of blood (e.g., 20 µL) from a capillary needle without the need
for phlebotomy. Clinical validation studies for CYA, TAC, and SIR with Mitra devices in adults were recently
reported. While one study showed a good correlation for TAC analysis, the other study showed inconsistency
with sample collection using Mitra devices. Therefore, the potential utility of Mitra devices for routine TDM is
uncertain. FDA-approved Tasso-M20 devices allow for an accurate, precise, painless, and consistent collection
of a fixed small volume of blood. However, the implementation of Tasso-M20 devices into the clinical setting for
TDM requires both analytical and clinical validation. The objectives of the proposed Microsampling Assays for
Immunosuppressive Drugs in childrEN (MAIDEN) study is to: 1) validate Tasso-M20 VAMS LC-MS/MS assays
for CYA, TAC, and SIR, 2) evaluate in vitro stability of CYA, TAC, and SIR in Tasso-M20 devices under the
conditions of shipping and storage, 3) clinically validate Tasso-M20 VAMS LC-MS/MS assays for CYA, TAC,
and SIR against current venous whole blood TDM immunoassays in pediatric patients, and 4) confirm the stability
of CYA, TAC, and SIR in Tasso-M20 VAMS clinical samples under the conditions of shipping and storage. If
successful, this research will enable the use of the microsampling method for TDM in the clinical setting
(obviating the need for invasive phlebotomy), and at home (reducing the burden on families to bring the
immunosuppressed children out of the home for routine TDM), and revolutionize remote sampling for TDM of
immunosuppressant drugs in children and adults.

## Key facts

- **NIH application ID:** 10285227
- **Project number:** 1R21HD106103-01
- **Recipient organization:** CHILDREN'S HOSP OF PHILADELPHIA
- **Principal Investigator:** Ganesh Moorthy
- **Activity code:** R21 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2021
- **Award amount:** $263,353
- **Award type:** 1
- **Project period:** 2021-07-10 → 2023-06-30

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10285227

## Citation

> US National Institutes of Health, RePORTER application 10285227, Microsampling Assays for Immunosuppressive Drugs in Children (1R21HD106103-01). Retrieved via AI Analytics 2026-05-22 from https://api.ai-analytics.org/grant/nih/10285227. Licensed CC0.

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