Reducing agalsidase beta infusion time in Fabry patients: low incidence of antibody formation and infusion-associated reactions in an Italian multicenter study

BACKGROUND

Fabry disease is a rare progressive X-linked lysosomal storage disease caused by mutations in the GLA gene that encodes α-galactosidase A. Agalsidase beta is a recombinant enzyme replacement therapy authorized in Europe at a standard dose of 1.0 mg/kg intravenously every other week at an initial infusion rate of ≤ 0.25 mg/min until patient tolerance is established, after which the infusion rate may be increased gradually. However, specific practical guidance regarding the progressive reduction in infusion time is lacking. This study investigated a new and specific protocol for reducing agalsidase beta infusion time in which a stable dosage of 15 mg/h is infused for the first four months, and the infusion rate is increased progressively from 15 to 35 mg/h for the subsequent four infusions. The shortest infusion time is reached after six months and maintained thereafter. The incidence of infusion-associated reactions (IARs) and the development of anti-drug antibodies were analyzed, and the disease burden and the clinical evolution of the disease at 12 months were evaluated.

RESULTS

Twenty-five of the 31 patients were naïve to enzyme or chaperone treatment at baseline and six patients had been switched from agalsidase alfa. The reduced infusion time protocol was well tolerated. Only one patient exhibited an IAR, with mild symptoms that resolved with low-dose steroids. Six patients globally seroconverted during treatment (4 with a classic phenotype and 2 with late-onset disease). All but three patients were seronegative at month 12. All patients were stable at the study's end (FAbry STabilization indEX value < 20%); reducing infusion time did not negatively impact clinical outcomes in any patient. The perceived medical assessment showed that the quality of life of all patients improved.

CONCLUSIONS

The study demonstrates that reducing agalsidase beta infusion time is possible and safe from both an immunogenic and clinical point of view. The use of a low infusion rate in the first months when the probability of onset of the development of antibodies is higher contributed to very limited seroconversion to antibody-positive status.

Occult HBV infection in hemodialysis setting is marked by presence of isolated antibodies to HBcAg and HCV

BACKGROUND

Hepatitis B virus (HBV) infections are a matter of concern in hemodialysis units; occult HBV infections (serum HBsAg negative but HBV DNA positive) were demonstrated in this setting, and this involves further concerns regarding possible transmission and pathogenic consequences. This study aimed to investigate the prevalence and correlates of occult HBV infection in a group of patients with reference to a single hemodialysis unit in southeastern Italy.

METHODS

We analyzed HBV serology and DNA (using a qualitative nested PCR) in 128 HBsAg-negative hemodialysis patients, and correlated the results obtained, with sex, age, hemodialysis duration and HCV seropositivity.

RESULTS

As a whole, occult HBV infection was demonstrated in 34/128 patients (26.6%); HBV DNA detection was more frequent when anti-HBcAg antibodies were detected in isolation (72%) than when associated with anti-HBsAg antibodies (31%). Among HCV-seropositive patients, occult HBV infection was observed in 66%, and among these as many as 14/15 patients (93%) who were HCV+/anti-HBcAg+ had serum HBV DNA detectable. On multivariate analysis, HCV seropositivity and the presence of anti-HBs were still respectively correlated to the presence and absence of occult HBV infection.

CONCLUSIONS

Occult HBV infection is frequent among hemodialysis patients in our geographical area, particularly correlated to the presence of isolated anti-HBcAg and anti-HCV antibodies. Thus, the presence of isolated anti-HBcAg should prompt the clinician to evaluate a possible occult HBV infection especially if anti-HCV antibodies are also detectable; this condition, in fact, seems to strongly predict the detection of HBV DNA.

[Nocturnal hemodialysis: an alternative treatment for a better quality of life]

The interest of investigators in intensified dialysis regimens has been growing in recent years, especially since the HEMO Study Group showed that a higher dose of thrice-weekly hemodialysis fails to reduce mortality and morbidity but improves clinical outcomes. Alternative hemodialysis strategies including short daily hemodialysis (SDHD), long hemodialysis (LHD) and nocturnal daily hemodialysis (NDHD) have been developed in the hope to improve patients' outcomes. A growing number of investigators are studying patients on alternative dialysis regimens and most publications in this field have reported significant improvements in clinical outcomes including left ventricular hypertrophy, blood pressure control, anemia, calcium-phosphate metabolism, and fluid and electrolyte balance; all of these parameters can be considered as indirect signs of improvement in quality of life. However, the strength of these results is often limited by shortcomings in study design. Indeed, in most of these studies an adequate control group is missing, the patient groups are not properly matched, and the number of patients enrolled is small. Similarly, most studies have evaluated the effects of NDHD and/or nocturnal LHD on health-related quality of life (HRQoL) by questionnaire administration. Even though better results might be achieved with nocturnal hemodialysis, no conclusive data exist to prove statistically significant differences in HRQoL between conventional and intensive hemodialysis. In conclusion, all of these novel dialysis strategies offer reliable opportunities for uremic patients, but further trials are needed to determine whether alternative hemodialysis can reduce morbidity and mortality in this high-risk population of patients.

A novel 7-modified camptothecin analog overcomes breast cancer resistance protein-associated resistance in a mitoxantrone-selected colon carcinoma cell line

We selected a mitoxantrone-resistant HT29 colon carcinoma cell line (HT29/MIT) that exhibited a very high degree of resistance to the selecting agent and marked resistance to topotecan and SN38, but limited resistance to doxorubicin. The development of drug resistance was independent of expression of P-glycoprotein or multidrug resistance-associated protein but was associated with high up-regulation of the breast carcinoma resistance protein (BCRP) as shown by Western blot analysis. BCRP overexpression was associated with a reduced intracellular accumulation of topotecan, a known substrate for BCRP. Conversely, a lipophilic 7-modified camptothecin analogue (ST1481) displayed a complete lack of cross-resistance in HT29/MIT cells, suggesting that the drug was not a substrate for BCRP because no defects in intracellular accumulation were found. This conclusion is consistent with the antitumor efficacy of ST1481 against a BCRP-expressing tumor. These results may have therapeutic implications because the antitumor efficacy of ST1481 is in part related to a good bioavailability after oral administration, and the drug is currently under Phase I clinical evaluation.

CYP21 analysis and phenotype/genotype relationship in the screened population of the Italian Emilia-Romagna region

OBJECTIVES

We have genotyped the patients with congenital adrenal hyperplasia due to 21-hydroxylase deficiency identified from March 1980 to December 1997 through a combined program of neonatal screening and case survey in the Emilia-Romagna Region (Italy). We have also analysed retrospectively the possible advantages of genotypical neonatal classification.

DESIGN

A 'phase A' of screening and clinical monitoring (March 1980-September 1983 and March 1991-December 1997) and a 'phase B' of clinical monitoring only (October 1983-February 1991) were taken into account.

PATIENTS

A total of 61 patients (20 salt wasting, nine simple virilizing and 32 nonclassical forms) were genotyped, HLA typed and hormonally tested to understand better the genotype/phenotype relationship and the epidemiology and geographical distribution of associated mutations. The fully genotyped patients were classified into four mutation groups according to the degree of enzymatic activity ('null' and 'A' to 'C').

RESULT

The most frequent genotype alterations were deletion (24.1% classical, 3.3% nonclassical forms), large gene conversion (9.2% classical, 1.7% nonclassical forms), In2 splice (27.7% classical, 15.0% nonclassical forms), I172N (5.5% classical, 10.0% nonclassical forms), V281L (3.7% classical, 43.3% nonclassical forms), P453S (5.0% nonclassical forms). A significant difference (chi2 = 5.101; P < 0.025) in the distribution of classical genotypes was found in Romagna (south-east; incidence 1 : 7437 newborns) compared to Emilia (north-west; incidence 1 : 25 090 newborns). Two putative new mutations were found in our population. Little discrepancy was found between genotype and phenotype.

CONCLUSIONS

The high frequency of genotypes 'null' or 'A' in the 'phase A' vs. 'phase B' of our study confirms the usefulness of neonatal screening in preventing the death of male patients with salt wasting forms. The substantial similarity in the mutational spectrum of classical forms found in our study, based on the detection of all the classical patients of a specific area, leads us to believe that the distribution of mutations is due to the inherent characteristics of the gene locus, and that regional effects play a minor role. Prompt neonatal genotyping can be of valuable diagnostic assistance in neonatal screening for the confirmation of the diagnosis in newborns with moderately elevated 17 hydroxyprogesterone levels.

Phenotypes of mouse diabetes and rat fatty due to mutations in the OB (leptin) receptor

Mice harboring mutations in the obese (ob) and diabetes (db) genes display similar phenotypes, and it has been proposed that these genes encode the ligand and receptor, respectively, for a physiologic pathway that regulates body weight. The cloning of ob, and the demonstration that it encodes a secreted protein (leptin) that binds specifically to a receptor (OB-R) in the brain, have validated critical aspects of this hypothesis. Here it is shown by genetic mapping and genomic analysis that mouse db, rat fatty (a homolog of db), and the gene encoding the OB-R are the same gene.

Gentle Touch, a lens material resistant to protein deposition

We investigated the ability of the Gentle Touch, a non-ionic contact lens material containing 35% netrafilcon A and 65% water, to repel protein deposits. Studies were conducted in vivo (lenses worn by patients) and in vitro (lenses coated by artificial tears). Acuvue soft contact lenses, an ionic lens material containing 42% etafilcon A and 58% water, were used as controls. After 1 to 2 weeks of wear, protein deposits on Gentle Touch lenses averaged 1.5-2.8 micrograms per lens versus 338-444 micrograms per lens for Acuvue. Gentle Touch lenses that were heat-coated with an FDA tear solution recommended for testing protein deposition averaged 6.5 micrograms of protein deposits per lens, whereas almost 100 micrograms of protein was deposited on each Acuvue lens. Lenses treated with an artificial tear solution deposited a non-detectable amount of protein on each Gentle Touch lens versus more than 358 micrograms on each Acuvue lens. These studies demonstrated that Gentle Touch lenses are highly resistant to protein deposits.

Phase I/pharmacokinetic reevaluation of thioTEPA

Because the initial evaluation of N,N',N''-triethylenethiophosphoramide (thioTEPA) preceded the standardized approach to the Phase I trials, uncertainty surrounds the recommended dose. Since it has recently been demonstrated that an almost 100-fold increase in dose can be administered in bone marrow transplant regimens, we conducted a Phase I reevaluation of thioTEPA. ThioTEPA was administered i.v. in 50 ml 5% dextrose in water over 10 min. Twenty-seven patients were entered at doses ranging from 30 to 75 mg/m2. The major toxic effect was myelosuppression; thrombocytopenia greater than or equal to grade 3 occurred in four of seven patients, and leukopenia greater than or equal to grade 3 in two of seven patients at 75 mg/m2. Among eight patients at 65 mg/m2 only two had greater than or equal to grade 3 myelosuppression making this the recommended new phase II dose for the majority of patients. Moderate (grade 2) easily controlled nausea and vomiting was the only other major side effect. There was no alopecia or mucosal or neurological toxicity. Three partial remissions were observed among nine previously treated ovarian cancer patients. Plasma concentrations of thioTEPA and its major active metabolite triethylenephosphoramide (TEPA) were measured by gas chromatography. The half-life of thioTEPA ranged from 51.6 to 211.8 min, and its pharmacokinetics was dose dependent; total body thioTEPA clearance decreased with increasing dose. The half-life of TEPA was considerably longer than that of the parent compound (3.0 to 21.1 h); as a result, the area under the plasma concentration-time curve (AUC) of TEPA was severalfold greater than that of the parent compound. The ratio of TEPA AUC to thioTEPA AUC decreased with increasing dose, suggesting that formation of TEPA is a saturable step in elimination. The AUC and total body clearance of thioTEPA, but not of TEPA, were closely correlated with neutrophil but not platelet toxicity.

Diffuse pigmented villonodular synovitis. An indication for total hip replacement in the young patient

Diffuse pigmented villonodular synovitis of the hip is a special problem because in this location it uniformly results in severe bony and cartilaginous destruction of the joint. In 2 cases treated by total hip replacement, both were successful at periods longer than 1 and 3 years follow-up with no evidence of recurrence of the disease, prosthetic failure, loosening, or any other complication despite the patients' young age and extremely active life styles. Continuous follow-up and frequent admonition about the wear erosion and recurrences of the synovitis is an essential part of the aftercare of these patients.