(T0930-09-53) Development and Validation of a Human Soluble MICA Biomarker Assay for use in Clinical Studies

Purpose: The MHC class I polypeptide-related sequence A (MICA) is a transmembrane protein that functions as a stress-induced ligand for NKG2D receptor. Engagement of NKG2D -MICA results in target cell killing. Data in literature demonstrated that serum soluble MICA (sMICA) level correlated with tumor progression. sMICA is an exploratory clinical biomarker for immuno-oncology programs.

Methods: Anti-MICA antibodies from internal and commercial sources have been screened for reactivity against the recombinant MICA extracellular domain and endogenous MICA in human serum. An antibody pair which recognizes both recombinant and endogenous MICA forms in the presence of BMS-986261 was selected. Fit-for-purpose biomarker method validation was conducted. Serum sMICA levels in normal and disease subjects were measured.

Results: The assay range of total sMICA in human serum was 25 - 40000 pg/mL. Accuracy of the calibration curve points were within 97 - 102% and had a CV ≤8%. QC performance was within acceptable limits, CV was below 10% for all QCs except LLOQ (with a 16% CV). The assay calibrator demonstrated parallelism with the endogenous analyte. Dilution linearity, specificity, stability and selectivity all recovered within ± 25% of the expected concentrations. Relative to normal serum, soluble MICA levels were not significantly different in serum samples from cancer patients.

Conclusion: The human total soluble MICA assay was developed and put under a fit for purpose validation strategy for its context of use on planned studies. The assay demonstrated high precision, sensitivity and suitability for the analysis of clinical samples.