Immunohistochemical evaluation of MYC expression in mantle cell lymphoma

Aim: To assess the validity and potential clinicalutility of evaluating MYC expression by immunohisto-chemistry (IHC) in mantle cell lymphoma (MCL).Methods and results: MYC IHC was scored on a tis-sue microarray containing 62 MCLs and 29 controlsby two pathologists. Inter-observer correlation washigh (intra-class correlation of 0.98). MYC IHCscores correlated with MYC expression (Spearman’srank correlation 0.69, P<0.0001) and weakly withKi67 proliferation index (Spearman’s rank correla-tion 0.30, P = 0.03). Six blastic MCLs did not havehigher mean MYC IHC scores or MYC mRNAexpression than non-blastic MCLs. None of 57 casesassessed, including all of the blastic cases, showedMYC rearrangement by fluorescence in-situ hybrid-ization. Multivariate analysis with backward selec-tion from potential predictors including age, lactatedehydrogenase, leukocyte count, MIPI score, ECOGperformance status, blastic morphology and Ki67index showed that MYC IHC score is an independentpredictor of progression-free survival (hazard ratio2.34, 95% CI 1.42–3.88, P = 0.0009) and overallsurvival (hazard ratio 1.90, 95% CI 1.05–3.43,P = 0.034).Conclusions: We show that a new monoclonal anti-MYC antibody can enable accurate and reproduciblevisual assessment of MYC expression that is indepen-dently predictive of clinical outcomes in MCL.Keywords: immunohistochemistry, mantle cell lymphoma, MYC, tissue microarray