MSD Immuno-Oncology 111/131-Plex Panel Services

The dual-epitope assays for PD-1 and PD-L1 are designed to address a critical question in Immuno-Oncologyresearch: when you measure soluble PD-1 or PD-L1 in plasma from a research participant receiving checkpoint inhibitor immunotherapy, are you measuring the native protein or the drug-bound complex? In the 111/131-Plex, PD-1 epitope 1 detects total PD-1 regardless of drug binding; PD-1 epitope 2 may be masked when PD-1 is occupied by therapeutic antibody (nivolumab, pembrolizumab), allowing distinction between free and total PD-1. Similarly, PD-L1 epitope 1 and epitope 2 provide differential detection of free vs. drug-bound PD-L1 (atezolizumab, durvalumab, avelumab). This dual-epitope approach enables assessment of target engagement — has the drug saturated its target? — independent of target expression level. For research use only; panels use manufacturer-documented MSD reagents.

The 111 analytes common to both panels use identical antibody pairs, calibrators, and plate configurations. Data for these 111 analytes are directly comparable between the 111-Plex and 131-Plex. The 131-Plex simply adds 20 additional analytes on separate electrode spots. For longitudinal studies where you start with the 111-Plex and later upgrade to the 131-Plex, the core 111-analyte data is continuous. We recommend documenting the configuration used for each batch in your study metadata.

High-dimensional biomarker data requires appropriate statistical handling to avoid false positives. We recommend: (1) Pre-specify primary analytes based on your biological hypothesis — don't treat 111 independent tests as all primary endpoints; (2) Multiple testing correction (Benjamini-Hochberg) for exploratory analyses; (3) Composite signature approaches — combining multiple correlated analytes into composite scores reduces dimensionality and improves statistical power; (4) Discovery-validation split — use a subset of samples for discovery, then validate candidate biomarkers on an independent cohort. Our data reports include both raw and adjusted p-values. For advanced statistical analysis (PCA, hierarchical clustering, machine learning), our scientific team can provide consultation or refer you to bioinformatics collaborators.

No. These panels are for research use only and are not validated for clinical irAE monitoring or prediction. However, several panel analytes are of research interest in the context of irAEs: IL-6, TNF-α, and IL-1β are elevated in cytokine release syndrome; IL-17 and IL-23 have been associated with checkpoint inhibitor colitis; and soluble CD40L has been studied in the context of immune activation. The 111/131-Plex can be used to explore these associations in a research context, but results should not be used for clinical management of irAEs.

Critical metadata for each sample: (1) Treatment regimen and cycle number; (2) Days since last dose — drug levels influence soluble target measurements; (3) Concomitant medications — particularly corticosteroids (within 14 days), G-CSF, and other immunomodulatory drugs; (4) irAE status and grade — immune-related adverse events can produce acute-phase cytokine changes; (5) Baseline (pre-treatment) sample — essential for distinguishing treatment-induced changes from pre-existing inter-individual variability; (6) Best response (RECIST or iRECIST) — for retrospective biomarker-response correlation. We provide standardized IO-specific sample manifest forms for metadata capture. All services are research use only.