Daratumumab Monotherapy for Relapsed or Refractory Multiple Myeloma: Results of an Early Access Treatment Protocol in Europe and Russia.

INTRODUCTION: Daratumumab is a human IgGκ monoclonal antibody targeting CD38. Despite the demonstrated benefit of daratumumab in multiple myeloma, not all patients have access to commercially available daratumumab. Here we report a pooled analysis of patients from the UK, Spain, Italy, and Russia enrolled in an open-label, early access treatment protocol (EAP) that provided daratumumab (16 mg/kg) monotherapy to patients with heavily pre-treated relapsed or refractory multiple myeloma (RRMM). METHODS: Intravenous daratumumab 16 mg/kg was administered to patients who had received ≥ 3 prior lines of therapy, including a proteasome inhibitor (PI) and an immunomodulatory drug (IMiD), or who were double refractory to both a PI and an IMiD. Safety and patient-reported outcomes data were collected. RESULTS: A total of 293 patients received ≥ 1 dose of daratumumab. The median duration of daratumumab exposure was 4.2 (range 0.03-24.1) months, with a median number of 13 (range 1-37) infusions. The overall response rate was 33.1%, and the median progression-free survival was 4.63 months. Grade 3/4 treatment-emergent adverse events occurred in 60.1% of patients, of which the most common were thrombocytopenia (18.8%), anemia (11.9%), and neutropenia (11.6%). The most common serious adverse events were pneumonia (4.4%) and pyrexia (4.1%). Infusion-related reactions occurred in 45.1% of patients. The median change from baseline in all domains of patient-reported outcome instruments (European Quality of Life Five Dimensions Questionnaire [EQ-5D-5L], European Organisation for Research and Treatment of Cancer [EORTC] Quality of Life Questionnaire [QLQ-C30], and EORTC Multiple Myeloma Module [QLQ-MY20]) was generally 0 or close to 0. CONCLUSION: These EAP results are consistent with those from previous trials of daratumumab monotherapy and confirm its safety in patients from Europe and Russia with heavily pre-treated RRMM. TRIAL REGISTRATION: ClinicalTrials.gov identifier, NCT02477891.

Plasmacytoma in patients with multiple myeloma: morphology and immunohistochemistry.

BACKGROUND: To study the histological structure and immunohistochemical (IHC) parameters of the plasmacytoma tumour substrate in patients with multiple myeloma (MM). METHODS: The study included 21 patients (10 men/11 women) aged 23 to 73 years old with newly diagnosed MM complicated by plasmacytoma. Bone plasmacytoma was diagnosed in 14 patients, and extramedullary plasmacytoma was diagnosed in 7 patients. Plasmacytoma tissue specimens were examined using a LEICA DM4000B microscope. Anti-CD56, anti-CD166, anti-CXCR4, anti-Ki-67, and anti-c-MYC antibodies were used for IHC study of plasmacytoma biopsies. RESULTS: When comparing the morphology of bone and extramedullary plasmacytoma, no significant differences were revealed; however, the substrate of extramedullary plasmacytoma was more often represented by tumour cells with an immature morphology than was the bone plasmacytoma substrate (57.1% vs. 28.6%, respectively). We revealed a significant difference in the expression of CD166 between bone and extramedullary plasmacytoma. The mean values ​​of CD166 expression in bone plasmacytoma cells were significantly higher (36.29 ± 7.61% versus 9.57 ± 8.46%, respectively; p = 0.033) than those in extramedullary plasmacytoma cells. We noticed that in extramedullary plasmacytoma cells, there were higher values for the Ki-67 index than in bone plasmacytoma cells, and this result was independent of cell morphology. CONCLUSION: The mechanisms involved in the dissemination of tumour plasma cells are currently unexplored. Even in such a small sample, some differences in expression could be identified, which may indicate that different mechanisms lead to the formation of bone and extramedullary plasmacytomas. Specifically, the expression of CD166 in extramedullary plasmacytoma cells was almost 4 times lower than that in bone plasmacytoma cells, which may indicate the involvement of CD166 in the mechanisms of bone destruction. The proliferative activity of extramedullary plasmacytoma cells was shown to be higher than that of bone plasmacytoma cells.

Thromboelastography, thrombin generation test and thrombodynamics reveal hypercoagulability in patients with multiple myeloma.

Patients with multiple myeloma (MM) are at increased risk of venous thromboembolism. Therefore, adequate laboratory control of hemostasis and subsequent adjustments of anticoagulant therapy are necessary. We studied hemostasis changes using thromboelastography (TEG), thrombin generation test (TGT) and thrombodynamics (TD) in primary MM patients (PMMpt, n=25) and patients in remission (RMMpt, n=34) during blood stem cell (BSC) mobilization. TD and TEG reveal hypercoagulability in PMMpt (*p<0.05) in relation to healthy volunteers. There was no difference in any of the tests between PMMpt and RMMpt. We detected no heparin effect in 22% of patients one day after the onset of the prophylactic heparin treatment (500 IU/h) during BSC mobilization; tests shifted toward the hypercoagulability in 75% of patients one day after cyclophosphamide (4 g/m2) chemotherapy. Global hemostasis tests were in good agreement with each other, revealed hypercoagulability and heparin "resistance" in patients with MM and may be useful for therapy individualization.