To assess the validity and potential clinical utility of evaluating MYC protein expression by immunohistochemistry (IHC) in mantle cell lymphoma (MCL).
Methods and results
MYC IHC was scored on a tissue microarray containing 62 MCL cases and 29 controls by two pathologists. Inter-observer correlation was high (intra-class correlation=0.98). MYC IHC scores correlated with MYC gene expression (Spearman’s 0.69, p<0.0001) and weakly with Ki-67 proliferation index (Spearman’s 0.30, p=0.03). Six cases of blastic MCL did not have higher mean MYC IHC scores or MYC mRNA expression than non-blastic MCL cases. None of 57 cases assessed, including all the blastic cases, showed MYC gene rearrangement by fluorescence in situ hybridization. Multivariate analysis using backward selection from potential predictors including age, lactate dehydrogenase, leukocyte count, MIPI score, ECOG performance status, blastic morphology, and Ki-67 index showed that MYC IHC score is an independent predictor of progression-free survival (hazard ratio=2.34, 95% CI 1.42 – 3.88, p=0.0009) and overall survival (hazard ratio=1.90, 95% CI 1.05 – 3.43, p=0.034).
We show that a new monoclonal anti-MYC antibody can enable accurate and reproducible visual assessment of MYC protein expression that is independently predictive of clinical outcomes in MCL.