Abstract
Daratumumab monotherapy was first investigated in GEN501 and SIRIUS trials in relapsed/refractory multiple myeloma (RRMM) patients, showing positive results. However, there is a lack of information on plasmacytoma response. We described a real-world study of 43 RRMM patients who received daratumumab monotherapy. The overall response rate (ORR) was 26%, and the clinical benefit rate (≥ minimal response) was 37%. Median time to best response, progression free survival (PFS), and overall survival (OS) were 2.9, 5.2, and 11.2 months respectively. Patients who achieved at least partial response had longer PFS and OS (12.8 and 20.2 months, respectively) than those who achieved minimal response or stable disease (5.3 and 11.2 months, respectively). Ten patients (23%) had plasmacytomas (70% paraskeletal, 30% extramedullary). In patients with plasmacytomas the ORR was 20%, in contrast to 27% observed in patients without plasmacytomas (p=0.5). Half of the patients with plasmacytomas achieved at least serological minimal response but only 20% had plasmacytoma response. This is the first real-world study of daratumumab monotherapy efficacy regarding soft-tissue plasmacytomas in patients with RRMM.
MicroAbstract
We report outcomes of relapsed/refractory multiple myeloma patients who received daratumumab monotherapy, with a special focus on plasmacytoma response. The overall response rate for patients with plasmacytomas was lower compared to those without plasmacytomas. Moreover, the serological response was not always associated with the plasmacytoma response. We consider that plasmacytoma response should be investigated in subgroup analysis in future trials.