[Prognostic Value of CD56 Expression in Newly Diagnosed Multiple Myeloma Patients and Its Related Factors]

Objective: To analyze the effect of CD56 expression on the prognosis of newly diagnosed multiple myeloma (MM) patients and explore the relationship between CD56 with clinical characteristics.

Methods: In this retrospective study, the clinical data and laboratory parameters of 175 newly diagnosed MM patients from February 2015 to December 2020 in the Second Hospital of Anhui Medical University were collected. The patients were divided into CD56⁺ and CD56^- groups based on the expression of CD56, and the general data and laboratory parameters of the two groups were compared. The patients were followed up to June 30, 2021, and progression-free survival (PFS) and overall survival (OS) were recorded. PFS and OS curves of the two groups were plotted respectively, and the survival differences were compared. Univariate and multivariate Cox regression analyses were performed to analyze the effect of CD56 on the prognosis of newly diagnosed MM patients.

Results: In 175 newly diagnosed MM patients, 57(32.6%) cases were in the CD56^-group and 118 (67.4%) cases in the CD56⁺ group. There was significant correlation between CD56 expression and ISS stage, ECOG score, platelets, β₂-microglobulin, creatinine, and extramedullary disease (all P <0.05). The incidence of extramedullary disease in the CD56^- group was significantly higher than that in the CD56⁺ group (29.8% vs 12.7%, P =0.006). The median follow-up time of the whole cohort was 23.6 (1.0-78.6) months. The median PFS of patients in CD56⁺ group and CD56^- group were 18.6 (1.2-77.6) and 12.2 (1.0-49.0) months, respectively, and the median OS of the two groups were 27.6 (1.4-77.7) and 19.7 (1.0-78.6) months, respectively. The 2-year PFS rate in the CD56⁺ group was significantly higher than that in the CD56^- group (57.6% vs 36.8%, P =0.010), and the 2-year OS rate in the CD56⁺ group was higher than that in the CD56^- group, but it didn't reach statistical significance (74.6% vs 64.9%, P =0.158). The results of univariate Cox regression analysis showed that the PFS was significantly shorter in newly diagnosed MM patients with advanced age, type IgG, high ECOG score, decreased platelet count, increased lactate dehydrogenase level, extramedullary disease, and CD56^- (all P <0.05), the OS was significantly shorter in patients with high ECOG score, decreased platelet count, increased lactate dehydrogenase level, extramedullary disease, and CD56^- (all P <0.05). The results of multivariate Cox regression analysis showed that advanced age, type IgG, elevated lactate dehydrogenase level, extramedullary disease, and CD56^- were independent prognostic factors for poor PFS (all P <0.05); and decreased platelet count, elevated lactate dehydrogenase level, and extramedullary disease were independent adverse prognostic factors for OS (all P <0.05), while there was no significant independent correlation between CD56 and OS (P >0.05).

Conclusion: Most of the newly diagnosed MM patients have positive expression of CD56. Loss of CD56 expression was associated with unfavorable biological and clinical parameters and poor prognosis, suggesting that CD56 has important clinical value in the prognosis of newly diagnosed MM patients.