Model-Based Exploration of the Impact of Prophylactic Tocilizumab on IL-6 Dynamics in Multiple Myeloma Patients Receiving Teclistamab Treatment

Introduction:Teclistamab is the only approved B-cell maturation antigen (BCMA) × CD3 bispecific antibody (BsAb) with personalized, weight-based dosing for the treatment of patients with triple-class exposed relapsed/refractory multiple myeloma (RRMM).In the MajesTEC-1 study (NCT03145181 and NCT04557098), the incidence of all grade (mostly grade 1 or 2) cytokine release syndrome (CRS) was 72.1% (Moreau et al. 2022). The cytokine interleukin-6 (IL-6) is found to be increased in the serum of patients with CRS (Shimabukuro-Vornhagen et al. 2018). Tocilizumab is a humanized IL-6 receptor-inhibiting monoclonal antibody. As a competitive antagonist, tocilizumab inhibits the IL-6 pathway by competing with IL-6 for binding to IL-6 receptor (IL-6R), resulting in lower IL-6R receptor occupancy (RO) by IL-6, thereby blocking IL-6 signaling. By blocking IL-6R, tocilizumab also reduces IL-6R-mediated IL-6 clearance, which leads to an increase in serum IL-6 levels (Uchiyama et al. 2008). It has been published previously that a single dose of prophylactic tocilizumab reduced the overall incidence of CRS to 26% after teclistamab administration, which represents a 64% reduction compared to the CRS incidence observed in MajesTEC-1 (van de Donk et al. 2023). A mechanism-based PK/PD model was used to evaluate the impact of tocilizumab prophylactic treatment on the soluble IL-6R (sIL-6R), IL-6 and the duration of the blockade of IL-6 signaling pathway in the patients following teclistamab treatment.