B. Calcoen MD

Gene therapy for von Willebrand Disease

SUMMARY

von Willebrand disease (VWD) is the most common inherited bleeding disorder, caused by mutations in the von Willebrand factor (VWF) gene. These mutations can affect the biosynthesis, secretion, function or clearance of VWF. As a result, quantitative or qualitative abnormalities of VWF lead to the bleeding phenotype found in VWD patients. Current management of VWD aims at correcting the bleeding phenotype via the use of supportive therapy, stimulating the release of endogenous VWF reserves and implementation of replacement strategies. Despite current treatment options, VWD patients experience a substantial negative impact on their overall health-related quality-of-life (HRQoL). Development of long-term approaches to manage VWD would not only avoid the current limitations of short-term therapies but could also significantly ameliorate the HRQoL of VWD patients. Gene therapy for VWD offers the potential of a long-term, if not lifelong, correction of VWF deficiency. During the last two decades, gene therapy for VWD has been studied via different strategies. The aim of this review is to give an overview of the different strategies and improvements that were investigated to develop a gene therapy for VWD.

(BELG J HEMATOL 2023;14(8):326–30)

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Defeating cytomegalovirus, the transplantation troll: can letermovir do the job?

Letermovir (AIC246, MK-8228) is a novel anti-cytomegalovirus (CMV) agent that inhibits CMV replication by targeting the viral terminase complex. In December 2017, letermovir was approved by the Food and Drug Administration (FDA) for the prophylaxis of CMV infection and disease in adult CMV-seropositive recipients of an allogenic haematological stem cell transplantation. Letermovir shows a favourable pharmacokinetic profile in haematological stem cell transplantation recipients after oral administration. The recommended dose for CMV-prophylaxis is once daily 480 mg (oral or intravenous). Letermovir demonstrated superiority in a placebo (plus polymerase chain reaction-monitoring and pre-emptive therapy)-controlled phase III randomised clinical trial. Letermovir is an inhibitor of the cytochrome P450 (CYP)3A family, CYP2B8 and an inducer of the CYP2C9/19. Dose-adjustments (240 mg/day) are necessary when letermovir is combined with cyclosporine. Combinations of letermovir with either voriconazole, midazolam and rosiglitazone require close monitoring of the plasma levels of the latter agents. Letermovir-resistant CMV mutants share mutations that are mostly located between the codon range 230–370 of the UL56 gene. Letermovir is not nephrotoxic nor myelotoxic, but slightly higher rates of atrial fibrillation and tachycardia have been described. In conclusion, letermovir is the first FDA approved anti-CMV agent for prophylaxis in haematological stem cell transplantation patients.

(BELG J HEMATOL 2019;10(4):136–45)

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O05 THE CONCENTRATION OF GP1BA MAGNETIC PARTICLES IS A CRITICAL PARAMETER OCCASIONALLY RESPONSIBLE FOR POOR REPRODUCIBILITY OF THE VWF:RCO WITH A CHEMILUMINESCENT IMMUNOASSAY

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