Ki67 and PIM1 expression in aggressively treated mantle cell lymphoma (MCL): A Cancer and Leukemia Group B (CALGB) 59909 correlative science study

8560 Background: Gene expression profiling has suggested that the proliferation signature is an important predictor of outcome in MCL. Retrospective studies have suggested that the proliferative index, measured by mitoses or Ki67, is an important prognostic indicator. This has not been validated in a US cooperative group setting or in the context of aggressive therapy. We assessed Ki67 and PIM1 (a cell cycle-related gene upregulated in blastoid MCL) expression in a prospective phase 2 cooperative group study. Methods: CALGB 59909 examined the efficacy of aggressive chemotherapy followed by autologous stem cell transplantation (ASCT) in untreated MCL patients less than 70 years of age. Cases with available material were studied for Ki67 and PIM1 expression by immunohistochemistry. Ki67 was quantitated by image analysis (IA Ki67) and manually as # positive cells/1000x hpf (Ki67-count). PIM1 staining was scored semi-quantitatively (0–3+). Progression-free survival (PFS) and disease-free survival (DFS) were t...