PB2005: BORTEZOMIB, LENALIDOMIDE AND DEXAMETHASONE IN NEWLY DIAGNOSED MULTIPLE MYELOMA PATIENTS: A REAL-WORLD STUDY OF CHINA

Abstract

Background: Multiple myeloma (MM) is a hematological malignancy characterized by the malignant proliferation of monoclonal plasma cells. In recent years, a series of new drugs such as proteasome inhibitors, immunomodulatory drugs and autologous hematopoietic stem cell transplantation (ASCT) have been widely used in MM patients and have prolonged the survival of them. Nowadays Bortezomib/lenalidomide/dexamethasone (VRD) is considered as the first-line induction therapy for newly diagnosed multiple myeloma (NDMM) in most clinical guidelines. However the data of VRD in China is insufficient. Aims: To evaluate the efficacy of VRD in NDMM patients as well as the effect of the regimen on the stem cell collection and on the long-term prognosis in the real world. Methods: The clinical characteristics, survival rates, response rates and minimal residual disease (MRD) of 87 NDMM patients at Institute of Hematology & Blood Diseases Hospital from January 1, 2013 to January 1, 2020 were retrospectively analyzed and the impact of lenalidomide on stem cell collection was evaluated. Response was evaluated after 2 courses of induction therapy, before ASCT and at day100 after ASCT. The best response was defined as the deepest response during the follow-up. MRD was evaluated by multiparameter flow cytometry (MFC) with 10-4 sensitivity. Results: The median age of the patients was 56 years old (36-78) and males and females accounted for 58.6% and 41.4%, respectively. The overall response rate (ORR) was 95.9% after 2 courses of induction therapy, with 13.5% achieving the deep response (complete response (CR) or better) and 51.3% of patients achieving a very good partial response (VGPR) or better. After 4 courses of induction therapy, the ORR achieved 95.2%, and the proportions of the deep response and VGPR or better grew up to 46.0% and 77.7%. According to the treatment, the patients were divided into transplantation group and non-transplantation group. After the induction therapy, 88.8% of patients in the transplantation group achieved VGPR or better, and 55.5% reached the deep response. After the transplantation, the proportion increased to 97.2% (P=0.174) and 77.2% (P=0.055), respectively, with the rate of undetectable MRD increasing from 44.4% to 77.8% (P=0.004). In the non-transplantation group, 78.9% of patients achieved VGPR or better after 4 courses of induction therapy, 44.7% of the patients achieved deep response and the rate of undetectable MRD was 42.4%. Compared with the non-transplantation group, transplantation was associated with a higher rate of response (P＜0.001) and a lower rate of MRD detection(78.4% vs 57.1%, P=0.053). The median follow-up time of all patients was 26.3 months (6.2-61.4). The median PFS and OS were not reached. The three-year PFS and OS rates were 82.1% and 87.0%, respectively. None of the standard-risk group, the high-risk group, the transplantation group and non-transplantation group achieved the median PFS and OS. The number of CD34+ positive cells tended to decrease after more than 4 courses of VRD induction therapies. Image:Summary/Conclusion: VRD regimen is highly effective and results in a substantial survival benefit. VRD followed by ASCT is associated with higher rate of deep response, lower rate of undetectable MRD and longer survival.