[Analysis of the clinical effects and outcome of patients with double-hit high-risk multiple myeloma]

Objective: To compare the clinical features, clinical efficacy, and prognosis of patients with double-hit and non-double-hit high-risk multiple myeloma (MM) and explored the clinical significance of high-risk cell karyotype in MM development. Methods: The clinical data of 73 high-risk MM patients admitted to the Department of Hematology of Fujian Provincial Hospital from January 2011 to February 2019 were retrospectively analyzed. Interphase fluorescence in situ hybridization was used to detect their karyotypes. Based on mSMART 3.0 risk stratification, we divided the patients into a double-hit group (28 cases) and a non-double-hit group (45 cases). Results: Fifteen patients in the double-hit group and 26 in the non-double-hit group received bortezomib-based chemotherapy. The median progression-free survival (PFS) in the double-hit and the non-double-hit groups was 8.0 months and 22.0 months, and the median overall survival (OS) was 10.0 months and not reached, respectively. Ten patients in the double-hit group and 12 in the non-double-hit group received bortezomib combined with lenalidomide (RVD) chemotherapy. The median PFS in the double-hit group and the non-double-hit group was 12.0 months and 24.0 months, and the median OS was 14.0 months and not reached, correspondingly. Both the PFS and OS of the double-hit group were significantly shorter than those of the non-double-hit group (P<0.05). Univariate analysis results indicated that cytogenetic abnormalities, revised-international staging system (R-ISS), β2 microglobulin, and calcium had significant effects on PFS in high-risk MM patients (P<0.05). The cytogenetic abnormalities, R-ISS, and β2 microglobulin were associated with OS in high-risk MM patients (P=0.001). Multivariate Cox regression analysis showed that the cytogenetic grouping was an independent prognostic factor for OS and PFS in high-risk MM patients. The risk of disease progression was 3.160 times (95% CI: 1.364-7.318) and the risk of death was 2.966 times higher (95%CI: 1.205-7.306) in the double-hit group than those in the non-double-hit group. Calcium was an independent risk factor for PFS in the high-risk MM patients. Notably, the risk of disease progression in patients with calcium levels≥ 2.75 mmol/L was 2.667 times higher than that in patients with calcium<2.75 mmol/L (95% CI: 1.209-5.883). Conclusions: Double-hit patients are a highly specific group with worse high-risk MM prognosis. In such patients, the relapse is more common, the disease progression is faster, and the survival time is shorter than those in the non-double-hit patients.