Clinical assessment of efficacy and safety of DDAVP

The efficacy of DDAVP (1-deamino-8-D-argi-nine-vasopressin, desmopressin) in mild haemophilia A and von Willebrand disease (VWD) has been established and the use of this well tolerated drug has become clinical routine. In case of increased fluid intake and based on very rarely occurring hyponatraemia, the indication of administration of DDAVP intravenously (i. v.) has to be performed diligently in elderly patients and in children below the age of five years. Aim, patients: Due to clinical practice we were interested in finding prospective parameter potentially correlating with adverse reactions of DDAVP and initiated this study. From 2007 to 2008, we included 49 patients suspicious to suffer from mild haemophilia A (n = 1) or VWD (n = 48) and investigated efficacy and safety of DDAVP after intravenous administration (mean: 0.29 ± 0.032 μg/kg body weight). They underwent clinical and laboratory investigation and were questioned with regard to potential adverse reactions immediately and three days after administration of DDAVP.: Results, conclusion: Most adverse reactions were mild and no serious adverse drug reactions were either observed or reported by the subjects. We identified significant changes of heart rate, blood pressure and leucocytes after conduct of the DDAVP test. The value of these findings has to be investigated in later prospective randomized studies. Further research on identification of prospective parameter is currently ongoing.

Next generation FIX muteins with FVIII-independent activity for alternative treatment of hemophilia A

BACKGROUND

FVIII neutralizing antibodies are the main complication of substitution therapy in hemophilia A (HA); auto-antibodies against FVIII causing acquired HA can also occur. Treatment of inhibitor patients remains challenging because prophylactic treatment with existing FVIII bypassing agents, all based on constitutively active coagulation factors, is difficult due to their short half-life.

OBJECTIVES

To generate zymogenic FIX variants with FVIII-independent activity for gene- and protein-based therapy for HA.

METHODS

Modifications were introduced into FIX based on current knowledge of FIX structure and FVIII-independent function followed by random screening. Activity, thrombin generation and FX activation by FIX mutants were characterized in the presence and absence of FVIII. Phenotype correction of promising candidates was assessed by the tail-clip assay in FVIII-knockout mice.

RESULTS

About 1600 clones were screened and three mutations (L6F, S102N and E185D) identified, which improved FVIII-independent activity in combination with our previously described variant FIX-ITV. By systematic combination of all mutations, six FIX mutants with the desired bypassing activity were designed. Candidate mutants FIX-IDAV and FIX-FIAV demonstrated the most efficient thrombin generation in FVIII-deficient plasma and had considerably increased activities towards FX in the absence of FVIII, in that they showed an up to 5-fold increase in catalytic efficiency. Expression of FIX-IDAV in FVIII knockout mice reduced blood loss after the tail-clip assay, even in the presence of neutralizing FVIII antibodies.

CONCLUSION

Activatable bioengineered FIX molecules (as opposed to pre-activated coagulation factors) with FVIII-independent activity might be a promising tool for improving HA treatment, especially for patients with inhibitors.

Oral gene therapy for hemophilia B using chitosan-formulated FIX mutants

BACKGROUND

Oral gene delivery of non-viral vectors is an attractive strategy to achieve transgene expression. Although expected efficacy from non-viral delivery systems is relatively low, repeated vector administration is possible and may help to obtain durable transgene expression in a therapeutic range.

OBJECTIVES

To test the principle feasibility of using factor (F) IX variants with improved function combined with an optimized oral delivery system in hemophilia B (HB) mice.

METHODS

FIX modifications were introduced by site-directed mutagenesis into plasmid- or minicircle-based expression cassettes. Vectors were formulated as chitosan nanoparticles for oral delivery to HB mice. Protection of vector DNA in nanoparticle constructs and transfection efficiency were characterized. HB mice received eGFP-formulated chitosan nanoparticles to confirm gene transfer in vivo. FIX expression, phenotype correction and the potential of nanoparticles to induce immunotolerance (ITI) against exogenous FIX were evaluated after repeated oral administration.

RESULTS

Transfection of HEK 293T cells or livers of FIX-knockout mice with nanoparticles resulted in GFP or functional FIX expression. Oral administration of FIX mutants resulted in exclusive FIX expression in the small intestine, as confirmed by RT-PCR and fluorescence staining. HB mice demonstrated transient FIX expression reaching > 14% of normal activity and partial phenotype correction after oral delivery of FIX mutants with high specific activity and improved tissue release.

CONCLUSION

The feasibility of oral, non-viral delivery of FIX was established and improved by bioengineered FIX proteins and optimized vectors. Thus, these data might point the way for development of a clinically applicable oral gene transfer strategy for hemophilia B.

Clinical assessment of efficacy and safety of DDAVP

The efficacy of DDAVP (1-deamino-8-D-arginine-vasopressin, desmopressin) in mild haemophilia A and von Willebrand disease (VWD) has been established and the use of this well tolerated drug has become clinical routine. In case of increased fluid intake and based on very rarely occurring hyponatraemia, the indication of administration of DDAVP intravenously (i. v.) has to be performed diligently in elderly patients and in children below the age of five years. Aim, patients: Due to clinical practice we were interested in finding prospective parameter potentially correlating with adverse reactions of DDAVP and initiated this study. From 2007 to 2008, we included 49 patients suspicious to suffer from mild haemophilia A (n = 1) or VWD (n = 48) and investigated efficacy and safety of DDAVP after intravenous administration (mean: 0.29±0.032 μg/kg body weight). They underwent clinical and laboratory investigation and were questioned with regard to potential adverse reactions immediately and three days after administration of DDAVP.

RESULTS, CONCLUSION

Most adverse reactions were mild and no serious adverse drug reactions were either observed or reported by the subjects. We identified significant changes of heart rate, blood pressure and leucocytes after conduct of the DDAVP test. The value of these findings has to be investigated in later prospective randomized studies. Further research on identification of prospective parameter is currently ongoing.

[Non-viral gene transfer results in therapeutic factor IX levels in haemophilia B mice]

Safety issues concerning the risk of malignancy formation and immune response to viral vectors were raised in initial gene therapy trials. In contrast, non-viral gene delivery methods have long been offside. We therefore explore a non-viral gene transfer approach for the treatment of hemophilia B.

METHODS

First, we constructed a strong liver-specific expression plasmid for human factor IX (FIX). Next, we tested the vector by injecting two doses under hydrodynamic conditions into the tail veins of FIX knockout mice.

RESULTS

A single injection resulted in an increase in FIX expression over 100% of normal plasma levels. The FIX resulted fully functional. Further, no anti-FIX antibodies were observed and expression levels were vector dose dependent.

CONCLUSION

The high expression obtained in small animals give hope for further development of non-viral gene transfer for the treatment of hemophilia B in humans.

Nicht-viraler Gentransfer führt zu therapeutischen Faktor-IX-Spiegeln im Hämophilie-B-Mausmodell

In ersten klinischen Gentherapiestudien mit viralen Vektoren sind Bedenken hinsichtlich des Risikos der Entstehung von Malignomen sowie bezüglich unerwarteter Immunantworten gegen virale Proteine aufgekommen. Im Gegensatz dazu standen nicht virale Therapien bisher eher im Abseits. In unserer Studie untersuchen wir daher einen nicht-viralen Ansatz zur Behandlung der Hämophilie B. Methodik: Zuerst wurde ein Expressionsplasmid für eine starke leberspezifische Faktor-IX(FIX)-Expression konstruiert. Um den Vektor zu testen, wurden Gruppen von FIX-Knockout-Mäusen zwei Vektordosierungen mittels hydrodynamischer Injektionstechnik appliziert. Ergebnis: Bereits eine einmalige Behandlung führte zu FIX-Expression oberhalb 100% normaler Plasmaspiegel. Das FIX-Protein war voll funktionsfähig, inhibitorische Antikörper gegen FIX wurden nicht beobachtet, Expressionsspiegel waren abhängig von der Vektordosis. Schlussfolgerung: Die hier vorgestellten FIX-Expressionsspiegel im Mausmodell geben Hoffnung auf die Weiterentwicklung nicht viraler Gentherapieansätzen zur Behandlung der Hämophilie B auch am Menschen.

The decanucleotide polymorphism in the factor VII promoter predicts factor VII plasma levels but not the risk of acute coronary syndromes

It is known from large epidemiological studies that the elevation of coagulation factor VII in plasma is an independent risk factor for acute coronary syndromes. The level of factor VII is influenced by polymorphic sites in the factor VII gene. However, data on the association of such polymorphisms with the risk of acute coronary syndromes are conflicting. A decanucleotide insertion/deletion polymorphic site has been described in the promoter of the factor VII gene that leads to a dramatic change in the plasma factor VII levels. We therefore analyzed the association of this polymorphism with the risk of acute coronary syndromes in a case-control study. Included in the study were 111 patients with angiographically documented acute coronary syndromes and 108 age- and sex-matched individuals from the same geographic area without signs or symptoms of coronary heart disease. The presence or absence of the decanucleotide stretch at position -323 in the promoter of factor VII was monitored using a polymerase chain reaction (PCR)-based restriction technique. The prevalence of the genotype with the homozygous deletion was similar in the patients with acute coronary syndromes (79.2%) and in the control patients (79.6%). There was a non-significant trend toward a higher prevalence of the homozygote deletion in patients with premature acute coronary syndromes (77.4%) compared with an age-matched subgroup of the control patients (67. 5%) (odds ratio [OR] 1.6, confidence interval [CI] 0.95, 0.61-3.93). Thus, we could not find a significant association of the occurrence of acute coronary events with the insertion/deletion polymorphism in factor VII.

Increased prevalence of a polymorphism in the gene coding for human prothrombin in patients with coronary heart disease

A number of genetic risk factors for the development of coronary heart disease has been identified in the past. Some of these represent polymorphisms in genes of proteins which are associated with the process of blood clotting. We investigated the distribution of a recently described G/A polymorphism in the 3'untranslated region of the human prothrombin gene (nt 20210) in 98 patients (19 female age: 53 + 12 SD years and 79 male, age: 49 + 8.5 SD years) with coronary heart disease and in 102 healthy newborns by enzymatic amplification of the genomic DNA carrying the polymorphic site and by subsequent restriction digest. The diagnosis of coronary heart disease was established by coronary angiography in all patients. The frequency of the A allele in the healthy newborns was 0.98% (0.2%-3.5%; CI 0.95) with the G/A genotype occurring in 1.96% (0.24%-6.9%; CI 0.95). In the group of patients with coronary heart disease the G/A genotype was found in 5.1% (1.7%-11.4%; CI 0.95). 94.9% of the patients studied showed a G/G genotype. The A/A genotype was neither detected in the newborns nor in the patients with coronary heart disease. This preliminary study strongly suggest that the presence of the G/A polymorphism in the 3'untranslated region of the gene coding for human prothrombin is associated with the occurrence of coronary heart disease.