Immunohistochemical detection of C-kit (CD117) and vascular endothelial growth factor (VEGF) overexpression in mantle cell lymphoma

Background: Mantle cell lymphoma (MCL) is a low-grade lymphoproliferative malignancy that is extremely refractory to chemotherapy. Commonly used treatments have yielded unfavorable response rates (30% complete remission). We evaluated the incidence of c-kit (CD117) and vascular endothelial growth factor (VEGF) overexpression in patients with MCL in an effort to identify possible targets for therapeutic intervention. Materials and Methods: Patients with a diagnosis of MCL based on CD5 positivity associated with cyclin D1 positivity and CD23 negativity on the lymph node/bone marrow specimen were included in our retrospective study. CD117 overexpression was performed using immunohistochemistry on archival specimens. VEGF expression was detected by the avidin-biotin-complex method. Results: Between 1997 and 2001, we identified 17 patients with MCL (9 males, 8 females) with a mean age of 57 years (age range: 42 - 66 years). The mean overall survival was 34 months (range: 11 - 60 months). VEGF expression was identified in 7 out of 17 (41.18%) patients with MCL. Among the VEGF- positive patients (n = 7, 41.1%), the mean survival was 24 months (range: 11 - 42 months), while patients without VEGF expression (n = 10, 58.9%) had a mean survival of 44 months (range: 21 - 60 months), CD117 expression was identified in only 2 out of 17 (1.17%) patients in our study. Conclusion: Our study evaluated the role of c-kit and VEGF overexpression in MCL. Although CD117 may not be of therapeutic significance, target-directed signal transduction inhibition therapy using VEGF- inhibitors may be a distinct possibility in a select group of patients with MCL. Future larger studies are urgently needed to elaborate the role of VEGF in MCL.