Clinical implications of c-maf expression in plasma cells from patients with multiple myeloma

Background: Multiple myeloma (MM) is a type of hematological malignancy with significant heterogeneity in clinical features and prognosis. Cytogenetic abnormalities are the major factors affecting patient outcomes. Studies have shown that immunohistochemistry (IHC)-based detection of cancer-related genes expression could be alternative indicators for the prognosis of MM. Methods: Nuclear expression of c-maf protein in the bone marrow plasma cells of 128 multiple myeloma patients were examined by IHC, and its association with the clinicopathological features of MM patients was analyzed as well. Results: Among the 128 patients, the positive rate of c-maf protein expression was up to 30.5%, which had no correlation with patient age, M protein type, Durie-Salmon staging system, the International Staging System, abnormal plasma cell ratio in the bone marrow, or the level of peripheral blood hemoglobin, serum calcium or lactate dehydrogenase. However, the c-maf-positive patients had a significantly higher rate of hypoproteinemia (p = 0.026) and higher serum beta 2-microglobulin levels (> 2500 mu g/ L) (p = 0.007). Patients with negative c-maf expression had higher remission rates upon the treatment of non-bortezomib-based regimens although no effect of c-maf expression on progression-free survival or overall survival was observed. Conclusion: Patients with negative c-maf expression had higher remission rates upon the treatment of non-bortezomib- based regimens although no effect of c-maf expression on survival was observed. A further large-scale prospective study is required to verify these findings.