Comparing the efficacy of different dexamethasone regimens for maintenance treatment of multiple myeloma in standard-risk patients non-eligible for transplantation.

Background: Multiple myeloma (MM) is a plasma cell malignancy, while MM outcomes have significantly improved due to novel agents and combinations, MM remains an incurable disease. The key goal of treatment in MM is to achieve a maximal response and the subsequent consolidation of response after initial therapy. Many studies analyzed an improved progression-free survival (PFS) following lenalidomide alone maintenance versus placebo or observation after autologous stem cell transplant (ASCT) in patients with NDMM. In the SWOG S0777 clinical trial, patients newly diagnosed with MM (NDMM) without ASCT received lenalidomide plus low-dose dexamethasone (DXM) maintenance until progressive disease, where PFS and overall survival (OS) were significantly improved. In the present study, we assessed the efficacy and toxicity of the different doses of DXM combined with lenalidomide for maintenance treatment of NDMM for transplant noneligible patients in the standard-risk group.

Aim: To investigate the efficacy and adverse effects of different administration modes of DXM combined with lenalidomide for maintenance treatment of MM in standard-risk patients ineligible for transplantation.

Methods: A total of 96 MM patients were enrolled in this study, among whom 48 patients received maintenance treatment that consisted of oral administration of 25 milligrams (mg) of lenalidomide from days 1-21 and 40 mg of DXM on days 1, 8, 15, and 22 (DXM 40 mg group), repeated every 4 wk. Another group was treated with oral administration of 25 mg of lenalidomide from days 1-21 and 20 mg of DXM on days 1-2, 8-9, 15-16, and 22-23 (DXM 20 mg group), which was also repeated every 4 wk.

Results: The median PFS was 37.25 mo in the DXM 40.00 mg group and 38.17 mo in the DXM 20 mg group ( = 0.171). The median OS was 50.78 mo in the DXM 40 mg group and 51.69 mo in the DXM 20 mg group ( = 0.171). Fourteen patients in the DXM 40 mg group and 6 patients in the DXM 20 mg group suffered from adverse gastrointestinal reactions after the oral administration of the DXM tablet ( = 0.044). Ten patients suffered from abnormal glucose tolerance (GTA), impaired fasting glucose (IFG), or diabetes mellitus in the DXM 40 mg group during our observation time compared to 19 patients with GTA, IFG, or DM in the DXM 20 mg group ( = 0.033). Abnormal β-crosslaps or higher were found in 5 patients in the DXM 40 mg group and 12 patients in the DXM 20 mg group ( = 0.049). Insomnia or an increase in insomnia compared to the previous condition was evident in 2 patients in the DXM 40 mg group after maintenance treatment for more than 6 mo compared to 11 patients in the DXM 20 mg group ( = 0.017).

Conclusion: The DXM 40 mg group exhibited efficacy similar to that of the DXM 20 mg group. However, the DXM 40 mg group had significantly decreased toxicity compared with the DXM 20 mg group in the long term.