Patients With Multiple Myeloma Have a Disbalanced Whole Blood Thrombin Generation Profile

Monoclonal whole IgG impairs both fibrin and thrombin formation: hemostasis and surface plasmon resonance studies

OBJECTIVES

Monoclonal gammopathies frequently associate with hemostatic alterations. Thrombotic events occur with high incidence particularly upon treatment, while in rarer cases hemorrhagic diathesis can be observed. The pathology of these tendencies could be caused by thrombocytopenia or hyperviscosity burden of circulating monoclonal antibodies. Studies also suggest interference of monoclonal antibodies with primary hemostasis. We isolated monoclonal whole IgG paraproteins from two myeloma patients to observe their effect on thrombin formation and fibrin polymerization.

METHODS

Monoclonal whole IgG was prepared from sera of two newly diagnosed untreated multiple myeloma patients and control normal plasma samples. Fibrin formation was measured using thrombin time and dilute prothrombin time tests and thrombin formation was detected with a fluorimetric thrombin generation assay. In addition, molecular interactions were investigated by surface plasmon resonance (SPR).

RESULTS

Thrombin time was prolonged upon addition of monoclonal IgG even at 30 g/L by 12 %, increasing up to 36 % at 60 g/L concentration. Dilute prothrombin time was prolonged by 20 % even at 30 g/L. Thrombin generation assay indicated an impairment in thrombin formation at the presence of monoclonal IgG compared to polyclonal at equivalent concentration. By an SPR assay we determined that both clonality IgG preparations interacted with fibrinogen, however interaction with human thrombin was only detected with monoclonal immunoglobulins (KD=1.03 × 10-7 M).

CONCLUSIONS

Here we provide evidence that isolated monoclonal whole IgG from myeloma patients can impair both fibrin and thrombin formation and we demonstrate by SPR assay that it interacts with components of the final phase of the coagulation system.

Association of routine hematological parameters with the development of monoclonal gammopathies: a case-control study of 134,740 patients : Resubmitted to annals of Hematology 26 March 2024

The diagnosis of multiple myeloma requires detection of paraproteinemia and confirmation of monoclonal bone marrow infiltration, along with signs of end-organ damage. Despite the increasing prevalence, serum paraproteinemia is not routinely measured. We examined the relationship between alterations in routine hematological parameters and the development of paraproteinemia in a case-control study. Data was retrieved from a laboratory database in the capital region of Denmark between 01/01/2012 and 31/12/2022. Patients were included if they had a test for paraproteinemia (n = 134,740) and at least one prior hematological parameter (white blood cells, hemoglobin and platelet count) with a minimum follow-up of 1 year.Between 96,999 and 103,590 patients were included in each of the three hematological groups. We found white blood cell count and the presence of paraproteinemia followed an inverse J-shaped curve, with the highest presence below 3 × 109/L and above > 9 × 109/L. The adjusted OR below and above the nadir of 4 × 109/L was 1.61 (95% CI 1.25; 2.08, p < 0.0001) and 1.03 (95% CI 1.03; 1.04, p < 0.0001). Hemoglobin levels were inversely associated the presence of paraproteinemia, with the highest association below 6 mmol/L with an OR of 1.30 (95% CI 1.28; 1.32, p < 0.0001) adjusted for age and gender. Platelet count followed a U-shaped curve with the highest association at < 100 × 109/L. The adjusted OR below and above the nadir of 250 × 109/L was 1.13 (95% CI 1.10; 1.17, p < 0.0001) and 1.10 (95% CI 1.08; 1.12, p < 0.0001) respectively. In conclusion, all three parameters showed significant association with later paraproteinemia.

Activated platelet-derived exosomal LRG1 promotes multiple myeloma cell growth

The hypercoagulable state is a hallmark for patients with multiple myeloma (MM) and is associated with disease progression. Activated platelets secrete exosomes and promote solid tumor growth. However, the role of platelet-derived exosomes in MM is not fully clear. We aim to study the underlying mechanism of how platelet-derived exosomes promote MM cell growth. Flow cytometry, Western blot, proteome analysis, co-immunoprecipitation, immunofluorescence staining, and NOD/SCID mouse subcutaneous transplantation model were performed to investigate the role of exosomal LRG1 on multiple myeloma cell growth. Peripheral blood platelets in MM patients were in a highly activated state, and platelet-rich plasma from MM patients significantly promoted cell proliferation and decreased apoptotic cells in U266 and RPMI8226 cells. Leucine-rich-alpha-2-glycoprotein 1 (LRG1) was significantly enriched in MM platelet-derived exosomes. Blocking LRG1 in recipient cells using LRG1 antibody could significantly eliminate the proliferation-promoting effect of platelet-derived exosomes on MM cells. And high exosomal LRG1 was associated with poor prognosis of patients with MM. Mechanistic studies revealed that LRG1 interacted with Olfactomedin 4 (OLFM4) to accelerate MM progression by activating the epithelial-to-mesenchymal transition (EMT) signaling pathway and promoting angiogenesis. Our results revealed that blocking LRG1 is a promising therapeutic strategy for the treatment of MM.

Identification and validation of a platelet-related signature for predicting survival and drug sensitivity in multiple myeloma

Background: Significant progress has been achieved in the management of multiple myeloma (MM) by implementing high-dose therapy and stem cell transplantation. Moreover, the prognosis of patients has been enhanced due to the introduction of novel immunomodulatory drugs and the emergence of new targeted therapies. However, predicting the survival rates of patients with multiple myeloma is still tricky. According to recent researches, platelets have a significant impact in affecting the biological activity of tumors and are essential parts of the tumor microenvironment. Nonetheless, it is still unclear how platelet-related genes (PRGs) connect to the prognosis of multiple myeloma. Methods: We analyzed the expression of platelet-related genes and their prognostic value in multiple myeloma patients in this study. We also created a nomogram combining clinical metrics. Furthermore, we investigated disparities in the biological characteristics, immunological microenvironment, and reaction to immunotherapy, along with analyzing the drug susceptibility within diverse risk groups. Results: By using the platelet-related risk model, we were able to predict patients' prognosis more accurately. Subjects in the high-risk cohort exhibited inferior survival outcomes, both in the training and validation datasets, as compared to those in the low-risk cohort (p < 0.05). Moreover, there were differences in the immunological microenvironments, biological processes, clinical features, and chemotherapeutic drug sensitivity between the groups at high and low risk. Using multivariable Cox regression analyses, platelet-related risk score was shown to be an independent prognostic influence in MM (p < 0.001, hazard ratio (HR) = 2.001%, 95% confidence interval (CI): 1.467-2.730). Furthermore, the capacity to predict survival was further improved when a combined nomogram was utilized. In training cohort, this outperformed the predictive value of International staging system (ISS) alone from a 5-years area under curve (AUC) = 0.668 (95% CI: 0.611-0.725) to an AUC = 0.721 (95% CI: 0.665-0.778). Conclusion: Our study revealed the potential benefits of PRGs in terms of survival prognosis of MM patients. Furthermore, we verified its potential as a drug target for MM patients. These findings open up novel possibilities for prognostic evaluation and treatment choices for MM.

Cryptogenic ischemic stroke in cardiac transthyretin amyloidosis and sinus rhythm: a case report

Cardiac amyloidosis is a group of diseases characterized by the deposition of amyloid fibers in cardiac tissue. Two forms are mainly reported: light chain (AL) and transthyretin (ATTR) amyloidosis. Among the complications of transthyretin amyloidosis there are thrombotic events and, to a lesser extent, hemorrhagic events. The latter are likely caused by perivascular amyloid deposition resulting in capillary fragility, in addition to INR lability during anticoagulant therapy. The onset of thrombotic events may be caused by the high prevalence of atrial fibrillation (AF), mechanical cardiac dysfunction and atrial myopathy observed in patients with transthyretin amyloidosis. It remains unclear why thromboembolic events occur even in patients with sinus rhythm or adequate anticoagulation, though a hypercoagulable state or underlying inflammation may be involved. We report a case of cryptogenic ischemic stroke in an 86-year-old woman with transthyretin amyloidosis and sinus rhythm. Traditional coagulation tests, whole blood rotational thromboelastometry and impedance aggregometry did not show a hypercoagulable state. The thrombin generation assay did not reveal a prothrombotic state. However, the study of extracellular vesicles highlighted underlying immune-mediated endothelial damage likely responsible for the thrombotic diathesis. It could be hypothesized that inflammation plays a role in the hypercoagulability of patients with transthyretin amyloidosis. Larger prospective studies are needed to validate our hypothesis.

Thrombosis in multiple myeloma: mechanisms, risk assessment and management

Multiple myeloma (MM) is associated with an increased risk of venous and arterial thrombosis. Pathophysiologic mechanisms include patient, disease and treatment related factors. Risk assessment models have been developed to determine whichpatients are at highest thrombotic risk and pursuant to this, risk adapted thrombosis prophylaxis has been suggested. Areas in which further basic and clinical research is imperative include the molecular and cellular mechanisms of thrombosis in myeloma, the inclusion of relevant biomarkers in risk assessment scores and controlled clinical trials of VTE prophylaxis and treatment using direct oral anticoagulants.

Crucial roles of red blood cells and platelets in whole blood thrombin generation

Red blood cells (RBCs) and platelets contribute to the coagulation capacity in bleeding and thrombotic disorders. The thrombin generation (TG) process is considered to reflect the interactions between plasma coagulation and the various blood cells. Using a new high-throughput method capturing the complete TG curve, we were able to compare TG in whole blood and autologous platelet-rich and platelet-poor plasma to redefine the blood cell contributions to the clotting process. We report a faster and initially higher generation of thrombin and shorter coagulation time in whole blood than in platelet-rich plasma upon low concentrations of coagulant triggers, including tissue factor, Russell viper venom factor X, factor Xa, factor XIa, and thrombin. The TG was accelerated with increased hematocrit and delayed after prior treatment of RBC with phosphatidylserine-blocking annexin A5. RBC treatment with ionomycin increased phosphatidylserine exposure, confirmed by flow cytometry, and increased the TG process. In reconstituted blood samples, the prior selective blockage of phosphatidylserine on RBC with annexin A5 enhanced glycoprotein VI-induced platelet procoagulant activity. For patients with anemia or erythrocytosis, cluster analysis revealed high or low whole-blood TG profiles in specific cases of anemia. The TG profiles lowered upon annexin A5 addition in the presence of RBCs and thus were determined by the extent of phosphatidylserine exposure of blood cells. Profiles for patients with polycythemia vera undergoing treatment were similar to that of control subjects. We concluded that RBC and platelets, in a phosphatidylserine-dependent way, contribute to the TG process. Determination of the whole-blood hypo- or hyper-coagulant activity may help to characterize a bleeding or thrombosis risk.

Bleeding and Thrombosis in Multiple Myeloma: Platelets as Key Players during Cell Interactions and Potential Use as Drug Delivery Systems

Multiple myeloma (MM) is a hematological malignancy originated in the bone marrow and characterized by unhindered plasma cell proliferation that results in several clinical manifestations. Although the main role of blood platelets lies in hemostasis and thrombosis, platelets also play a pivotal role in a number of other pathological conditions. Platelets are the less-explored components from the tumor microenvironment in MM. Although some studies have recently revealed that MM cells have the ability to activate platelets even in the premalignant stage, this phenomenon has not been widely investigated in MM. Moreover, thrombocytopenia, along with bleeding, is commonly observed in those patients. In this review, we discuss the hemostatic disturbances observed in MM patients and the dynamic interaction between platelets and myeloma cells, along with present and future potential avenues for the use of platelets for diagnostic and therapeutic purposes.