Performance of the Lymph2Cx assay in the independent validation cohort. (A) The Lymph2Cx model is shown in the form of a gene expression heatmap (upper) with 67 patient samples from the independent validation cohort arrayed left to right in ascending order of the assay score. The 20 genes that contribute to the model are shown at the left, with the top 8 genes being overexpressed in ABC, the middle 5 genes being housekeeping genes, and the lower 7 genes being overexpressed in GCB. (Lower) The cell-of-origin assignments are shown for the assay, the gold standard method using previously published algorithms⁶  on gene expression from FT and 3 immunohistochemistry-based algorithms. The Lymph2Cx results shown are from the Molecular Characterization Laboratory (FNLCR, Frederick, MD), with 1 of the 68 cases in the independent validation cohort having failed. Results from the Centre for Lymphoid Cancer, BC Cancer Agency, Vancouver, BC Canada, are shown in supplemental Figure 2. (B) Comparison of the Lymph2Cx scores in the validation cohort from the 2 independent laboratories: the Molecular Characterization Laboratory (MoCha) (Frederick National Laboratory for Cancer Research) and the CLC, BC Cancer Agency. The dotted lines represent the thresholds between GCB, unclassified, and ABC. The 66 of 68 cases where both laboratories generated results are shown. The 3 cases that gave discordant COO assignments are shown in red. The concordance is 98%, when considering the ABC and GCB cases by the gold standard method, and 95% if the unclassified cases are included. The R² is 0.996, and the slope of the line of best fit is 1.015. Comparisons in the training and total cohorts are shown in supplemental Figure 3.