Impaired efferocytosis by monocytes in multiple myeloma

Efficient clearance of apoptotic cells by efferocytosis is important for tissue homeostasis. Impaired efferocytosis leads to the accumulation of cell debris, which is regarded as a trigger in chronic inflammation and autoimmune diseases. Patients with hematological neoplastic disorders such as multiple myeloma (MM) exhibit high blood levels of apoptotic microparticles. The present study investigated whether these high levels of apoptotic microparticles are associated with insufficient dead cell clearance. Blood samples were collected from patients with MM immediately prior to and 3, 7 and 10 days after the initial cycle of bortezomib-based therapy. In addition, bone marrow aspirates (BMA) were collected prior to and following therapy. Prior to therapy, a 52% reduction in efferocytosis by blood monocytes was observed compared with the healthy controls (P<0.017). This was associated with an elevated number of 7-AAD⁺ dead cell remnants in the blood flow as well as in BMA. A portion of the blood samples contained active caspase 3. The subsequent bortezomib-based therapy had no effect on efferocytosis, although the quantity of dead cell remnants decreased. This reduction was associated with a decline in cluster of differentiation 8 (CD8)⁺ and CD4⁺ T cells and an increase in the number of monocytes. However, of 28 distinct soluble immune-modulating molecules (i.e. chemokines, cytokines and soluble co-stimulators) only C-C motif chemokine ligand 2 (CCL2), CCL24 and sCD27 were affected by bortezomib-based therapy. The levels of all other molecules remained unchanged or were below the detection threshold in all samples. The present study results revealed that the presence of dead cell remnants in the blood and bone morrow of patients with MM is associated with impaired efferocytosis by monocytes; however, its contribution to inflammatory events during MM remains unclear.

Multiparameter flow cytometry evaluation of plasma cell DNA content and proliferation in 595 transplant-eligible patients with myeloma included in the Spanish GEM2000 and GEM2005<65y trials

The incorporation of high-dose therapy/autologous stem cell transplantation (HDT/ASCT) and novel agents has significantly improved survival in patients with multiple myeloma (MM), but whether this improvement also benefits patients harboring poor prognostic features, such as nonhyperdiploid MM (NH-MM) and a high proliferation index, remains largely unknown. We analyzed the DNA content and proliferation index of bone marrow plasma cells (PCs) by multiparameter flow cytometry in 595 newly diagnosed transplant-eligible patients with MM included in two consecutive PETHEMA/GEM trials: GEM2000 [VBMCP/VBAD (vincristine, carmustine, melphalan, cyclophosphamide, prednisone/vincristine, bischloroethylnitrosourea, adriamycin, and dexamethasone) followed by HDT/ASCT; n = 319] and GEM2005<65y (randomized induction with VBMCP/VBAD/bortezomib or thalidomide/dexamethasone or bortezomib/thalidomide/dexamethasone followed by HDT/ASCT; n = 276). Of the 595 patients, 295 were classified as NH-MM (49.6%) and 336 (56.5%) as high-proliferative MM (≥1% PCs in S-phase). Detection of NH-MM DNA content and ≥1% PCs in S-phase were of independent prognostic value for overall survival. Treatment with bortezomib-based regimens abrogated the inferior overall survival of patients with ≥1% PCs in S-phase but not of patients with NH-MM. Finally, a comparative analysis of PC proliferation index at diagnosis versus disease progression showed a twofold increase at relapse in 44 of 52 patients (85%) analyzed at both time points. NH-MM and a high proliferation index assessed by multiparameter flow cytometry remain as independent prognostic factors in MM, but the latter may be overcome by incorporating novel agents in the HDT/ASCT setting.

Combined measurement of plasma cell proliferative and apoptotic index in multiple myeloma defines patients with good and poor prognosis

We assessed plasma cell proliferation (by propidium iodide index, PC-PI) and apoptosis (by annexin-V index PC-AI) for the estimation of overall survival (OS) in multiple myeloma (MM) patients. 181 patients with newly diagnosed MM were assessed, treated using conventional chemotherapy. The values best discriminating patients with poor prognosis were PC-PI>3.0% and PC-AI<4.75%, and for good prognosis PC-PI≤3.0% and PC-AI≥4.75%. The median OS was 8 months vs 40 months, p=0.0002. Our results suggest that combined measurement of plasma cell proliferation and apoptosis creates a unique strong prognostic factor based on growth characteristics of the tumor clone.