MM-722 Lymphocyte Profiling in Newly Diagnosed Multiple Myeloma: First-Line Treatment with Cyclophosphamide Thalidomide, Dexamethasone, and Daratumumab

• Published in: Clinical lymphoma, myeloma and leukemia myeloma and leukemia, 2024-09, Vol.24, p.S580-S580
• Main Authors: Santos, Allan, Santos, Mariane, Leal, Joanna, Santos, Herbert, Santos, Juliana, Lucas, Larissa, Aurelio Salvino, Marco, da Gloria Bomfim, Maria, Hungria, Vania, Torres, Alex, Crusoé, Edvan
• Format: Article
• Language: English
• Subjects: CTd; daratumumab; lymphocytes; multiple myeloma
• ISSN: 2152-2650
• DOI: 10.1016/S2152-2650(24)01725-7

In the last decade, therapeutic advances have led to an increase in the overall survival of patients with multiple myeloma (MM); however, the disease remains incurable. Therapeutic protocols combining alkylating agents, immunomodulators, proteasome inhibitors, and immunotherapy induce an immunological shift that is still not fully understood. The aim of this study was to quantify lymphocyte subpopulations and B-cell subsets in patients with newly diagnosed MM (NDMM) eligible for autologous stem cell transplant (ASCT) using first-line therapy with cyclophosphamide, thalidomide, and dexamethasone combined with daratumumab (Dara-CTd). Between 2018 and 2022, 23 NDMM patients had their lymphocyte profiles analyzed at 5 distinct time points: at diagnosis, after induction therapy, after 2 consolidation cycles post-ASCT, before maintenance therapy, and 1 year after the start of the maintenance phase. Flow cytometry was used to detect lymphocyte subsets by surface molecules, including CD3, CD4, CD5, CD8, CD16, CD19, CD20, CD38, CD45, and CD56 in the scatter plot. B cells were isolated, and subpopulations (naïve B cells, non-class-switched memory B cells, class-switched memory B cells, IgD-CD27 memory B cells, and plasmablasts) were detected by CD20, CD24, CD27, CD38, CD45, and IgD. Statistics were performed using the SPSS® v25.0. The median age was 58 (range: 37-67), and 57% were female. It was observed that the treatment induced significant changes in the lymphocyte profile, with emphasis on the decrease in B cells and NK cells (P ≤ .05). The composition of the B cell subsets changed significantly throughout the treatment. T cells significantly decreased after the induction phase but recovered soon post-ASCT. Although not statistically significant, higher lymphocyte counts were observed with higher overall survival and undetectable measurable residual disease by next-generation flow (NGF). The present study confirmed that Dara-CTd induced a decrease in the number of different lymphocyte populations (T, B, and NK cells) after induction therapy with Dara-CTd. The T cell number recovered after 2 consolidation cycles post-ASCT, but B and NK cells remained at low levels during treatment with slow recovery.