Low frequency of CD3⁺CD4⁺CD161⁺ T cells correlates with the occurrence of infections in refractory/relapsed multiple myeloma patients receiving lenalidomide plus low-dose dexamethasone treatment

The aim of this study was to explore the predictive implications of the composition of immune cell populations prior to lenalidomide plus high-dose dexamethasone (Len-Dex) initiation for the occurrence of infections. We prospectively examined immune cell populations in peripheral blood taken at baseline of lenalidomide plus low-dose dexamethasone (Len-dex) therapy and reviewed clinical and microbiology records in 90 patients with refractory/relapsed multiple myeloma (RRMM). Risk factors for infection were analyzed using logistic regression. During a median of 11 cycles of Len-dex treatment, 52 (57.8%) patients experienced at least 1 infection episode. Of a total of 92 episodes of infection, 58 (63%) episodes were clinically defined, 29 (31.5%) episodes were microbiologically defined, and 5 (5.4%) episodes were fever of unknown origin. Severe episodes were more frequently observed during the first 3 cycles. After adjusting for risk factors for infection based on univariate analyses, multivariate analyses showed that lower Hb (< 10 g/dL) was a clinically independent factor associated with occurrence of infections. Lower frequency (P = 0.044) and absolute count (P = 0.014) of circulating CD3⁺CD4⁺CD161⁺ cells prior to Len-dex treatment were also associated with the occurrence of infection, especially during the first 3 cycles of Len-dex therapy. In addition to several clinical predictive factors, we found that CD3⁺CD4⁺CD161⁺ cells may provide additional information for predicting the occurrence of infection in the early period of Len-dex therapy.