Combined Immune Defect in B-Cell Lymphoproliferative Disorders Is Associated with Severe Infection and Cancer Progression

This research received no external funding. K.G.-H is supported by The European Social Fund (ESF) through a Río Ortega Grant for Health Research Projects by the Carlos III Health Institute (ISCIII) (CM20/00098).B cell chronic lymphoproliferative diseases (B-CLPD) are associated with secondary antibody deficiency and other innate and adaptive immune defects, whose impact on infectious risk has not been systematically addressed. We performed an immunological analysis of a cohort of 83 B-CLPD patients with recurrent and/or severe infections to ascertain the clinical relevance of the immune deficiency expression. B-cell defects were present in all patients. Patients with combined immune defect had a 3.69-fold higher risk for severe infection (p = 0.001) than those with predominantly antibody defect. Interestingly, by Kaplan–Meier analysis, combined immune defect showed an earlier progression of cancer with a hazard ratio of 3.21, than predominantly antibody defect (p = 0.005). When B-CLPD were classified in low-degree, high-degree, and plasma cell dyscrasias, risk of severe disease and cancer progression significantly diverged in combined immune defect, compared with predominantly antibody defect (p = 0.001). Remarkably, an underlying primary immunodeficiency (PID) was suspected in 12 patients (14%), due to prior history of infections, autoimmune and granulomatous conditions, atypical or variegated course and compatible biological data. This first proposed SID classification might have relevant clinical implications, in terms of predicting severe infections and cancer progression, and might be applied to different B-CLPD entities.Depto. de Inmunología, Oftalmología y ORLFac. de MedicinaTRUEpu

Therapy-Related Myeloid Neoplasms as a Concerning Complication in Acute Promyelocytic Leukemia

Acute promyelocytic leukemia (APL) has become a highly curable malignant disease after the introduction of all transretinoic acid (ATRA) to chemotherapy treatment. However, the risk to develop therapy-related myeloid neoplasms (t-MN) has become a matter of concern, as APL patients are otherwise expected to have a good prognosis. We report a patient with APL who achieved complete remission after chemotherapy induction with anthracycline and ATRA, followed by consolidation and maintenance chemotherapy. Two years later, the patient developed t-AML, with MLL rearrangements, without any evidence of relapse of the APL original clone. The increasing incidence of t-MN in oncohematological patients is partly due to the development of safer, more efficient or targeted therapies, which allow better outcomes and lengthened survival amongst treated patients. The identification of genetic factors, mechanisms or prognostic biomarkers in t-MN might open new windows for the development of personalized targeted therapy regimes in this underserved patient population

A Novel Antibody against Human Factor B that Blocks Formation of the C3bB Proconvertase and Inhibits Complement Activation in Disease Models

The alternative pathway (AP) is critical for the efficient activation of complement regardless of the trigger. It is also a major player in pathogenesis, as illustrated by the long list of diseases in which AP activation contributes to pathology. Its relevance to human disease is further emphasized by the high prevalence of pathogenic inherited defects and acquired autoantibodies disrupting components and regulators of the AP C3-convertase. Because pharmacological downmodulation of the AP emerges as a broad-spectrum treatment alternative, there is a powerful interest in developing new molecules to block formation and/or activity of the AP C3-convertase. In this paper, we describe the generation of a novel mAb targeting human factor B (FB). mAb FB48.4.2, recognizing with high affinity an evolutionary-conserved epitope in the Ba fragment of FB, very efficiently inhibited formation of the AP C3-proconvertase by blocking the interaction between FB and C3b. In vitro assays using rabbit and sheep erythrocytes demonstrated that FB28.4.2 was a potent AP inhibitor that blocked complement-mediated hemolysis in several species. Using ex vivo models of disease we demonstrated that FB28.4.2 protected paroxysmal nocturnal hemoglobinuria erythrocytes from complement-mediated hemolysis and inhibited both C3 fragment and C5b-9 deposition on ADP-activated HMEC-1 cells, an experimental model for atypical hemolytic uremic syndrome. Moreover, i.v. injection of FB28.4.2 in rats blocked complement activation in rat serum and prevented the passive induction of experimental autoimmune Myasthenia gravis. As a whole, these data demonstrate the potential value of FB28.4.2 for the treatment of disorders associated with AP complement dysregulation in man and animal models