Pharmacodynamics of asfotase alfa in adults with pediatric-onset hypophosphatasia

BACKGROUND

Hypophosphatasia (HPP) is the rare, inherited, metabolic bone disease characterized by low activity of the tissue-nonspecific isoenzyme of alkaline phosphatase (TNSALP) leading to excess extracellular inorganic pyrophosphate (PPi) and pyridoxal 5'-phosphate (PLP). Asfotase alfa is the human recombinant enzyme-replacement therapy that replaces deficient TNSALP. However, there is limited information concerning the appropriate dose of asfotase alfa for adult patients with pediatric-onset HPP. Thus, we evaluated the pharmacodynamics and safety/tolerability of different doses of asfotase alfa in such patients.

METHODS

This 13-week, Phase 2a, open-label study enrolled adults (aged ≥18 years) with pediatric-onset HPP. They were randomized 1:1:1 to receive a single subcutaneous dose of asfotase alfa (0.5, 2.0, or 3.0 mg/kg) at Week 1, then 3 times per week (ie, 1.5, 6.0, or 9.0 mg/kg/wk) starting at Week 3 for 7 weeks. Key outcome measures included change from Baseline to before the third dose during Week 9 (trough) in plasma PPi (primary outcome measure) and PLP (secondary outcome measure).

RESULTS

Twenty-seven adults received asfotase alfa 0.5 (n = 8), 2.0 (n = 10), and 3.0 (n = 9) mg/kg; all completed the study. Median (range) age was 45 (18-77) years; most patients were white (96%) and female (59%). Median plasma PPi and PLP concentrations decreased from Baseline to Week 9 in all 3 cohorts. Differences in least squares mean (LSM) changes in PPi were significant with 2.0 mg/kg (p = 0.0008) and 3.0 mg/kg (p < 0.0001) vs. 0.5 mg/kg. Differences in LSM changes in PLP were also significant for 2.0 mg/kg (p = 0.0239) and 3.0 mg/kg (p = 0.0128) vs. 0.5 mg/kg. Injection site reactions were the most frequent treatment-emergent adverse event (78%), showing increasing frequency with increasing dose.

CONCLUSIONS

Adults with pediatric-onset HPP receiving asfotase alfa at 6.0 mg/kg/wk (the recommended dose) or 9.0 mg/kg/wk had greater reductions in circulating PPi and PLP concentrations compared with a lower dose of 1.5 mg/kg/wk.

TRIAL REGISTRATION

Clinicaltrials.gov identifier NCT02797821.

Burden of disease in pediatric patients with hypophosphatasia: results from the HPP Impact Patient Survey and the HPP Outcomes Study Telephone interview

Background

Hypophosphatasia (HPP) is a rare, inherited, metabolic bone disease caused by deficient tissue-non-specific isoenzyme of alkaline phosphatase activity that manifests as a broad range of signs/symptoms, including bone mineralization defects and systemic complications. The burden of disease is poorly characterized, particularly in children. This study aimed to characterize the patient-reported burden of disease among children with HPP using two survey instruments: the HPP Impact Patient Survey (HIPS) and the HPP Outcomes Study Telephone interview (HOST).

Methods

Between September 2009 and June 2011, pediatric patients (aged younger than 18 years) with HPP were recruited to participate in the study via patient advocacy groups or their medical provider. Survey questions were used to capture information on patient demographics, HPP-related medical history, mobility, and health-related quality of life (HRQoL; using the 10-item Short-Form Health Survey for Children [SF-10], HIPS only).

Results

Common clinical features of the 59 pediatric survey respondents (mean [standard deviation] age: 7.6 [5.1] years; 51% male) included pain (86% of patients), muscle weakness (71%), difficulty gaining weight (64%), and delayed walking (59%). Fracture was reported by 36% of patients; multiple fractures were also reported (15% of patients). Use of assistive devices for mobility was frequent among the study population (51%). In response to the SF-10, patients reported a substantial impact of HPP on their HRQoL; physical function was the most severely impaired component relative to normative data. Of patients responding to the HOST, two-thirds experienced worsening of at least one of their HPP-related signs/symptoms over a 5-year period.

Conclusions

In pediatric patients, HPP is associated with a high burden of disease and a substantial negative impact on HRQoL. The burden of HPP may increase and HRQoL reduce further over time as signs/symptoms that affect HRQoL worsen or new signs/symptoms manifest.

Electronic supplementary material

The online version of this article (10.1186/s13023-019-1167-5) contains supplementary material, which is available to authorized users.

Efficacy and Safety of Asfotase Alfa in Infants and Young Children With Hypophosphatasia: A Phase 2 Open-Label Study

CONTEXT

Long-term data on enzyme replacement treatment of hypophosphatasia (HPP) are limited.

OBJECTIVE

To evaluate efficacy and safety of asfotase alfa in patients aged ≤5 years with HPP followed for up to 6 years.

DESIGN

Phase 2 open-label study (July 2010 to September 2016).

SETTING

Twenty-two sites; 12 countries.

PARTICIPANTS

Sixty-nine patients [median (range) age: 16.0 (0.02 to 72) months] with severe HPP and sign/symptom onset before age 6 months.

INTERVENTION

Asfotase alfa 2 mg/kg three times/week or 1 mg/kg six times/week subcutaneously.

MAIN OUTCOME MEASURES

Primary efficacy measure: Radiographic Global Impression of Change (RGI-C) score [-3 (severe worsening) to +3 (complete/near-complete healing)]. Additional outcome measures: respiratory status, growth, and safety. Post hoc analysis: characteristics of radiographic responders vs nonresponders at Year 1 (RGI-C: ≥+2 vs <+2).

RESULTS

During median (minimum, maximum) 2.3 (0.02, 5.8) years of treatment, RGI-C scores improved significantly at Month 6 [+2.0 (-1.7, +3.0)], Year 1 [+2.0 (-2.3, +3.0)], and Last Assessment [+2.3 (-2.7, +3.0); P < 0.0001 all]. Of 24 patients requiring respiratory support at Baseline, 11 (46%) no longer needed support. Height/weight z scores generally increased. Nine patients died (13%). All patients experienced at least one adverse event; pyrexia was most common. Compared with responders [n = 50 (72%)], nonresponders [n = 19 (28%)] had more severe disease at Baseline and a higher rate of neutralizing antibodies (NAbs) at Last Assessment.

CONCLUSIONS

Most infants/young children given asfotase alfa showed early radiographic and clinical improvement sustained up to 6 years; radiographic nonresponders had more severe disease and more frequent NAbs at Last Assessment.

Natural History of Perinatal and Infantile Hypophosphatasia: A Retrospective Study

OBJECTIVE

To report clinical characteristics and medical history data obtained retrospectively for a large cohort of pediatric patients with perinatal and infantile hypophosphatasia.

STUDY DESIGN

Medical records from academic medical centers known to diagnose and/or treat hypophosphatasia were reviewed. Patients born between 1970 and 2011 with hypophosphatasia and any of the following signs/symptoms at age <6 months were eligible: vitamin B6-dependent seizures, respiratory compromise, or rachitic chest deformity (NCT01419028). Patient demographics and characteristics, respiratory support requirements, invasive ventilator-free survival, and further complications of hypophosphatasia were followed for up to the first 5 years of life.

RESULTS

Forty-eight patients represented 12 study sites in 7 countries; 13 patients were alive, and 35 were dead (including 1 stillborn). Chest deformity, respiratory distress, respiratory failure (as conditioned by the eligibility criteria), failure to thrive, and elevated calcium levels were present in >70% of patients between birth and age 5 years. Vitamin B6-dependent seizures and respiratory distress and failure were associated significantly (P < .05) with the risk of early death. Serum alkaline phosphatase activity in all 41 patients tested (mean [SD]: 18.1 [15.4] U/L) was below the mean lower limit of normal of the reference ranges of the various laboratories (88.2 U/L). Among the 45 patients with relevant data, 29 had received respiratory support, of whom 26 had died at the time of data collection. The likelihood of invasive ventilator-free survival for this cohort decreased to 63% at 3 months, 54% at 6 months, 31% at 12 months, and 25% at 5 years.

CONCLUSIONS

Patients with perinatal or infantile hypophosphatasia and vitamin B6-dependent seizures, with or without significant respiratory distress or chest deformities, have high morbidity and mortality in the first 5 years of life.

TRIAL REGISTRATION

ClinicalTrials.gov: NCT01419028.

Five-year efficacy and safety of asfotase alfa therapy for adults and adolescents with hypophosphatasia

Hypophosphatasia (HPP) features low tissue-nonspecific alkaline phosphatase (TNSALP) isoenzyme activity resulting in extracellular accumulation of its substrates including pyridoxal 5'-phosphate (PLP), the principal circulating form of vitamin B6, and inorganic pyrophosphate (PPi), a potent inhibitor of mineralization. Asfotase alfa is an enzyme replacement therapy developed to treat HPP. This multinational, randomized, open-label study (NCT01163149; EudraCT 2010-019850-42) evaluated the efficacy and safety of asfotase alfa in adults and adolescents 13-66 years of age with HPP. The study comprised a 6-month primary treatment period and a 4.5-year extension phase. In the primary treatment period, 19 patients were randomized to receive asfotase alfa 0.3 mg/kg/d subcutaneously (SC; n = 7), asfotase alfa 0.5 mg/kg/d SC (n = 6), or no treatment (control; n = 6) for 6 months. In the extension phase, patients received asfotase alfa (0.5 mg/kg/d for 6 mo-1 y, then 1 mg/kg/d 6 d/wk). During the primary treatment period, changes from Baseline to Month 6 in plasma PLP and PPi concentrations (coprimary efficacy measure) were greater in the combined asfotase alfa group compared with the control group, reaching statistical significance for PLP (P = 0.0285) but not for PPi (P = 0.0715). However, for the total cohort, the within subject changes in both PLP and PPi after 6 months and over 5 years of treatment with asfotase alfa were significant (P < 0.05). Secondary efficacy measures included transiliac crest histomorphometry, dual-energy X-ray absorptiometry (DXA), and the 6-Minute Walk Test (6MWT). A significant decrease from Baseline in mineralization lag time was observed in the combined asfotase alfa group at Year 1. There were no significant differences between treated and control patients in DXA mean bone mineral density results at 6 months; Z-scores and T-scores were within the expected range for age at Baseline and remained so over 5 years of treatment. On the 6MWT, median (min, max) distance walked increased from 355 (10, 620; n = 19) meters before treatment to 450 (280, 707; n = 13) meters at 5 years (P < 0.05). Results for the exploratory outcome measures suggested improvements in gross motor function, muscle strength, and patient-reported functional disability over 5 years of treatment. There were no deaths during this study. Asfotase alfa was generally well tolerated; the most common adverse events were mild to moderate injection site reactions. This study suggests that in adults and adolescents with pediatric-onset HPP, treatment with asfotase alfa is associated with normalization of circulating TNSALP substrate levels and improved functional abilities.

Reliability and Validity of the 6-Minute Walk Test in Hypophosphatasia

This investigation evaluated the reliability and validity of the 6‐Minute Walk Test (6MWT) in patients with pediatric hypophosphatasia (HPP). Children (aged 6 to 12 years; n = 11), adolescents (13 to 17 years; n = 4), and adults (18 to 65 years; n = 9) completed the 6MWT at screening and baseline in two clinical studies of asfotase alfa. Test‐retest reliability of the 6MWT, evaluated with Pearson's correlation coefficients (r) for screening versus baseline, was high for children (r = 0.95; p < 0.0001), adolescents (r = 0.81; p = 0.125), and adults (r = 0.94; p = 0.0001). The most conservative minimal clinically important differences, estimated using distribution‐based methods, were 31 m (children and adults) and 43 m (adolescents). In children, the 6MWT correlated significantly with scores on measures of skeletal disease, which included the Radiographic Global Impression of Change scale (r = 0.50; p < 0.0001) and the Rickets Severity Scale (r = −0.78; p < 0.0001), such that distance walked increased as the severity of skeletal disease decreased. Significant (p < 0.0001) correlations with the 6MWT distance walked were also observed for children with scores on parent‐reported measures of disability (r = −0.67), ability to function in activities of daily living (r = 0.71 to 0.77), and parent‐reported measures of pain (r = −0.39). In adolescents and adults, 6MWT distance walked correlated significantly (p < 0.05) with measures of lower extremity function (r = 0.83 and 0.60, respectively), total pain severity (r = −0.41 and −0.36, respectively), and total pain interference (r = −0.41 and −0.49, respectively). Collectively, these data indicate that the 6MWT is a reliable, valid measure of physical functioning in patients with pediatric HPP. © 2018 The Authors. JBMR Plus Published by Wiley Periodicals, Inc. on behalf of the American Society for Bone and Mineral Research.

Asfotase alfa for infants and young children with hypophosphatasia: 7 year outcomes of a single-arm, open-label, phase 2 extension trial

BACKGROUND

Our previous phase 2, open-label study of 11 infants and young children with life-threatening perinatal or infantile hypophosphatasia showed 1 year safety and efficacy of asfotase alfa, an enzyme replacement therapy. We aimed to report the long-term outcomes over approximately 7 years of treatment.

METHODS

We did a prespecified, end of study, 7 year follow-up of our single-arm, open-label, phase 2 trial in which children aged 3 years or younger with life-threatening perinatal or infantile hypophosphatasia were recruited from ten hospitals (six in the USA, two in the UK, one in Canada, and one in the United Arab Emirates). Patients received asfotase alfa (1 mg/kg three times per week subcutaneously, adjusted to 3 mg/kg three times per week if required) for up to 7 years (primary treatment period plus extension phase) or until the product became commercially available; dosage adjustments were made at each visit according to changes in the patient's weight. The primary objectives of this extension study were to assess the long-term tolerability of asfotase alfa, defined as the number of patients with one or more treatment-emergent adverse events, and skeletal manifestations associated with hypophosphatasia, evaluated using the Radiographic Global Impression of Change (RGI-C) scale (-3 indicating severe worsening, and +3 complete or near-complete healing). Respiratory support, growth, and cognitive and motor functions were also evaluated. All efficacy and safety analyses were done in all patients who received any asfotase alfa (full-analysis population). This study and extension phase are registered with ClinicalTrials.gov, number NCT01205152, and EudraCT, number 2009-009369-32.

FINDINGS

11 participants were recruited between Oct 6, 2008, and Dec 4, 2009. Ten patients completed a 6 month treatment period and entered the extension phase; nine received asfotase alfa for at least 6 years and completed the study, with four being treated for more than 7 years. Skeletal healing was sustained over 7 years of treatment; all evaluable patients had RGI-C scores of at least +2 at year 6 (n=9; median score +2·0 [range 2·0-3·0]) and year 7 (n=7; median score +2·3 [2·0-3·0]). No patient who completed the study required respiratory support after year 4. Weight Z scores improved to within normal range from year 3 to study end; length or height Z scores improved but remained below normal. Age-equivalent scores on gross motor, fine motor, and cognitive subscales of the Bayley Scales of Infant and Toddler Development also improved. All 11 patients had at least one treatment-emergent adverse event. The most common adverse events were pyrexia (eight [73%] of 11 patients), upper respiratory tract infection (eight [73%]), craniosynostosis (seven [64%]), and pneumonia (seven [64%]). Serious adverse events related to asfotase alfa occurred in three (27%) patients (severe chronic hepatitis; moderate immediate post-injection reaction; and severe craniosynostosis with severe conductive deafness).

INTERPRETATION

Patients with perinatal or infantile hypophosphatasia treated with asfotase alfa for up to 7 years showed early, sustained improvements in skeletal mineralisation. Respiratory function, growth, and cognitive and motor function also improved, and asfotase alfa was generally well tolerated.

FUNDING

Alexion Pharmaceuticals, Inc.

Validation of a Novel Scoring System for Changes in Skeletal Manifestations of Hypophosphatasia in Newborns, Infants, and Children: The Radiographic Global Impression of Change Scale

Hypophosphatasia (HPP) is the heritable metabolic disease characterized by impaired skeletal mineralization due to low activity of the tissue-nonspecific isoenzyme of alkaline phosphatase. Although HPP during growth often manifests with distinctive radiographic skeletal features, no validated method was available to quantify them, including changes over time. We created the Radiographic Global Impression of Change (RGI-C) scale to assess changes in the skeletal burden of pediatric HPP. Site-specific pairs of radiographs of newborns, infants, and children with HPP from three clinical studies of asfotase alfa, an enzyme replacement therapy for HPP, were obtained at baseline and during treatment. Each pair was scored by three pediatric radiologists ("raters"), with nine raters across the three studies. Intrarater and interrater agreement was determined by weighted Kappa coefficients. Interrater reliability was assessed using intraclass correlation coefficients (ICCs) and by two-way random effects analysis of variance (ANOVA) and a mixed-model repeated measures ANOVA. Pearson correlation coefficients evaluated relationships of the RGI-C to the Rickets Severity Scale (RSS), Pediatric Outcomes Data Collection Instrument Global Function Parent Normative Score, Childhood Health Assessment Questionnaire Disability Index, 6-Minute Walk Test percent predicted, and Z-score for height in patients aged 6 to 12 years at baseline. Eighty-nine percent (8/9) of raters showed substantial or almost perfect intrarater agreement of sequential RGI-C scores (weighted Kappa coefficients, 0.72 to 0.93) and moderate or substantial interrater agreement (weighted Kappa coefficients, 0.53 to 0.71) in patients aged 0 to 12 years at baseline. Moderate-to-good interrater reliability was observed (ICC, 0.57 to 0.65). RGI-C scores were significantly (p ≤ 0.0065) correlated with the RSS and with measures of global function, disability, endurance, and growth in the patients aged 6 to 12 years at baseline. Thus, the RGI-C is valid and reliable for detecting clinically important changes in skeletal manifestations of severe HPP in newborns, infants, and children, including during asfotase alfa treatment. © 2018 The Authors. Journal of Bone and Mineral Research Published by Wiley Periodicals Inc.

Burden of disease in adult patients with hypophosphatasia: Results from two patient-reported surveys

BACKGROUND

Hypophosphatasia (HPP) is a rare metabolic bone disease caused by loss-of-function mutation(s) in the tissue-nonspecific alkaline (TNSALP) phosphatase gene, which manifests as rickets and/or osteomalacia with systemic complications and affects patients of all ages. The burden of disease is poorly characterized in adult patients.

AIMS

We assessed patient-reported burden of disease using two surveys reasonably specific for HPP symptomatology, the Hypophosphatasia Impact Patient Survey (HIPS) and the Hypophosphatasia Outcomes Study Telephone interview (HOST).

METHODS

Patients with HPP were invited to participate via patient advocacy groups or their medical provider. Survey questions captured demography, HPP-related medical history, mobility, and health-related quality of life (using Short Form 12 [version 2] Health Survey [SF-12v2]) via internet report (HIPS) or telephone interview (HOST).

RESULTS

One hundred twenty-five adults responded (mean [standard deviation, SD] age: 45 [14.3] years). Eighty-four patients (67%) reported pediatric-onset of their symptoms. Common clinical features in the study population included pain (95% of patients), fractures (86% of patients) muscle weakness (62%) and unusual gait (52%). Use of assistive devices for mobility (60%) was also prevalent. Twenty-six percent of patients reported more than 10 fractures. Seventy-four percent of patients had undergone orthopedic/dental surgical procedures. The health profile of patients responding on the SF-12 showed a broad and substantial impact of HPP on health-related quality of life, with domains related to physical ability showing the greatest decrement compared to normative data.

CONCLUSIONS

In aggregate, these data indicate that HPP can confer a high burden of illness in adulthood.

Asfotase alfa therapy for children with hypophosphatasia

Background. Hypophosphatasia (HPP) is caused by loss-of-function mutation(s) of the gene that encodes the tissue-nonspecific isoenzyme of alkaline phosphatase (TNSALP). Consequently, cell-surface deficiency of TNSALP phosphohydrolase activity leads to extracellular accumulation of inorganic pyrophosphate, a natural substrate of TNSALP and inhibitor of mineralization. Children with HPP can manifest rickets, skeletal pain, deformity, fracture, muscle weakness, and premature deciduous tooth loss. Asfotase alfa is a recombinant, bone-targeted, human TNSALP injected s.c. to treat HPP. In 2012, we detailed the 1-year efficacy of asfotase alfa therapy for the life-threatening perinatal and infantile forms of HPP. Methods. Here, we evaluated the efficacy and safety of asfotase alfa treatment administered to children 6-12 years of age at baseline who were substantially impaired by HPP. Two radiographic scales quantitated HPP skeletal disease, including comparisons to serial radiographs from similarly affected historical control patients. Results. Twelve children receiving treatment were studied for 5 years. The 6-month primary endpoint was met, showing significant radiographic improvement. Additional significant improvements included patient growth, strength, motor function, agility, and quality of life, which for most patients meant achieving normal values for age- and sex-matched peers that were sustained at 5 years of treatment. For most, pain and disability resolved. Mild to moderate injection-site reactions were common and were sometimes associated with lipohypertrophy. Low anti-asfotase alfa antibody titers were noted in all patients. No evidence emerged for clinically important ectopic calcification or treatment resistance. Conclusions. Asfotase alfa enzyme replacement therapy has substantial and sustained efficacy with a good safety profile for children suffering from HPP. Trial Registration. ClinicalTrials.gov NCT00952484 (https://clinicaltrials.gov/ct2/show/NCT00952484) and NCT01203826 (https://clinicaltrials.gov/ct2/show/NCT01203826). Funding. Alexion Pharmaceuticals Inc. and Shriners Hospitals for Children.

Asfotase Alfa Treatment Improves Survival for Perinatal and Infantile Hypophosphatasia

CONTEXT

Hypophosphatasia (HPP) is an inborn error of metabolism that, in its most severe perinatal and infantile forms, results in 50-100% mortality, typically from respiratory complications.

OBJECTIVES

Our objective was to better understand the effect of treatment with asfotase alfa, a first-in-class enzyme replacement therapy, on mortality in neonates and infants with severe HPP.

DESIGN/SETTING

Data from patients with the perinatal and infantile forms of HPP in two ongoing, multicenter, multinational, open-label, phase 2 interventional studies of asfotase alfa treatment were compared with data from similar patients from a retrospective natural history study.

PATIENTS

Thirty-seven treated patients (median treatment duration, 2.7 years) and 48 historical controls of similar chronological age and HPP characteristics.

INTERVENTIONS

Treated patients received asfotase alfa as sc injections either 1 mg/kg six times per week or 2 mg/kg thrice weekly.

MAIN OUTCOME MEASURES

Survival, skeletal health quantified radiographically on treatment, and ventilatory status were the main outcome measures for this study.

RESULTS

Asfotase alfa was associated with improved survival in treated patients vs historical controls: 95% vs 42% at age 1 year and 84% vs 27% at age 5 years, respectively (P < .0001, Kaplan-Meier log-rank test). Whereas 5% (1/20) of the historical controls who required ventilatory assistance survived, 76% (16/21) of the ventilated and treated patients survived, among whom 75% (12/16) were weaned from ventilatory support. This better respiratory outcome accompanied radiographic improvements in skeletal mineralization and health.

CONCLUSIONS

Asfotase alfa mineralizes the HPP skeleton, including the ribs, and improves respiratory function and survival in life-threatening perinatal and infantile HPP.

A Randomized, Double-Blind, Placebo-Controlled Dose-Escalation Trial of Merimepodib (VX-497) and Interferon-α in Previously Untreated Patients with Chronic Hepatitis C

Inhibition of inosine monophosphate dehydrogenase (IMPDH) is one of several proposed mechanisms of action for ribavirin (RBV), a critical component of the current treatment for chronic hepatitis C (CHC).

This study was a double-blind, placebo-controlled dose-escalation study of a novel, selective, orally active small molecule inhibitor of IMPDH, merimepodib (VX-497 or MMPD) in combination with standard interferon-alpha (IFN-α). Fifty-four treatment-naive patients with genotype-1 CHC were randomized to receive IFN-α 3 MIU subcutaneously three times a week, alone or in combination with 100 mg or 300 mg (every 8 h) of MMPD for 4 weeks. At the end of 4 weeks, all patients were offered 48 weeks of treatment with IFN-α/RBV. The objectives of the study were to evaluate the tolerability of the IFN-α/MMPD combination and to evaluate whether MMPD had an on-treatment effect on HCV-RNA, similar to RBV when added to IFN-α.

The drug combination was generally well tolerated; one patient at the higher dose discontinued because of elevated alanine aminotransferase levels. No pharmacokinetic interactions were evident between the two drugs. Analysis of covariance that adjusted for a baseline imbalance in HCV-RNA in the intent-to-treat population did not show any significant differences between the treatment groups, or between MMPD plus IFN-α compared with IFN-α alone. However, the per-protocol primary efficacy analysis based on treatment-compliant patients demonstrated a greater reduction in mean HCV-RNA in the combination of 100 mg MMPD plus IFN-α compared with IFN-α alone (-1.78 log vs -0.86 log, P=0.037).

In conclusion, the addition of a selective IMPDH inhibitor to IFN-α was well tolerated. In a low-dose range, the addition of MMPD may have the potential to add to the antiviral efficacy of IFN-α. Larger, longer duration trials incorporating pegylated IFN would be required to determine whether this combination, alone or with RBV, would increase either early or sustained virological response rates.

A randomized, double-blind, placebo-controlled dose-escalation trial of merimepodib (VX-497) and interferon-alpha in previously untreated patients with chronic hepatitis C

Inhibition of inosine monophosphate dehydrogenase (IMPDH) is one of several proposed mechanisms of action for ribavirin (RBV), a critical component of the current treatment for chronic hepatitis C (CHC). This study was a double-blind, placebo-controlled dose-escalation study of a novel, selective, orally active small molecule inhibitor of IMPDH, merimepodib (VX-497 or MMPD) in combination with standard interferon-alpha (IFN-alpha). Fifty-four treatment-naive patients with genotype-1 CHC were randomized to receive IFN-alpha 3 MIU subcutaneously three times a week, alone or in combination with 100 mg or 300 mg (every 8 h) of MMPD for 4 weeks. At the end of 4 weeks, all patients were offered 48 weeks of treatment with IFN-alpha/RBV. The objectives of the study were to evaluate the tolerability of the IFN-alpha/MMPD combination and to evaluate whether MMPD had an on-treatment effect on HCV-RNA, similar to RBV when added to IFN-alpha. The drug combination was generally well tolerated; one patient at the higher dose discontinued because of elevated alanine aminotransferase levels. No pharmacokinetic interactions were evident between the two drugs. Analysis of covariance that adjusted for a baseline imbalance in HCV-RNA in the intent-to-treat population did not show any significant differences between the treatment groups, or between MMPD plus IFN-alpha compared with IFN-alpha alone. However, the per-protocol primary efficacy analysis based on treatment-compliant patients demonstrated a greater reduction in mean HCV-RNA in the combination of 100 mg MMPD plus IFN-alpha compared with IFN-alpha alone (-1.78 log vs -0.86 log, P=0.037). In conclusion, the addition of a selective IMPDH inhibitor to IFN-alpha was well tolerated. In a low-dose range, the addition of MMPD may have the potential to add to the antiviral efficacy of IFN-alpha. Larger, longer duration trials incorporating pegylated IFN would be required to determine whether this combination, alone or with RBV, would increase either early or sustained virological response rates.

The novel IMPDH inhibitor VX-497 prolongs skin graft survival and improves graft versus host disease in mice

VX-497 is the first inosine-5'-monophosphate dehydrogenase (IMPDH) inhibitor generated in a structure-based drug design program specifically addressing the tolerability problems of currently available immunosuppressive drugs. The pharmacological activity of the compound has been examined in murine skin transplantation and graft versus host disease (GVHD) models. In the skin transplant study, trunk skin grafts from Balb/c mice were grafted onto C57Bl/6 mice. Mice were administered vehicle or VX-497 twice daily until day 10. Mean survival of skin grafts on vehicle-treated animals was 9.9 +/- 0.9 days. Graft survival was prolonged significantly in animals treated with VX-497 to 13.2 +/- 1.2 (p < 0.001, Kaplan Meier Log-Rank test) days in the 50 mg/kg group and 13.9 +/- 1.0 (p < 0.001) days in the 85 mg/kg group. In the GVHD study, 150 x 10(6) nonadherent splenocytes from B6 mice were injected intravenously into the F1 hybrid strain B6DBA/2. Groups of animals (n = 6) were administered vehicle or 50 or 100 mg/kg VX-497 b.i.d for 8 days. Animals were sacrificed and spleen weights and interferon-gamma (IFN-gamma) serum levels were determined by enzyme-linked immunosorbent assay. In addition, spontaneous spleen cell proliferation was measured using a 3H-thymidine uptake assay. Isografted F1 animals served as controls. GVHD developed in the vehicle-treated allografted F1 mice and treatment with VX-497 improved all manifestations of the disease significantly. The 2.9-fold increase in spleen weight in allografted animals was reduced to a 1.6-fold increase in the VX-497-treated mice. Serum IFN-gamma levels were increased 54-fold in the vehicle group while there was a 7.4-fold increase in VX-497-treated animals. Spontaneous spleen cell proliferation was increased 9.9-fold in the absence of VX-497 and there was a 3.5-fold increase in its presence. Thus, VX-497 has been shown to be effective in both a skin transplantation and a GVHD model in the mouse. The demonstrated pharmacological activity of VX-497 in these murine transplantation models warrants further evaluation of the drug in transplantation indications.

Polymorphic markers for the arylsulfatase A gene reveal a greatly expanded meiotic map for the human 22q telomeric region

Two microsatellite markers, D22S1743 and D22S1744, were developed for the arylsulfatase A (ARSA) region of chromosome 22q. Linkage analysis for 171 families, using nine reference markers covering all of 22q, placed these new markers 2.0 Kosambi cM distal to D22S526, making them more distal than any microsatellite markers currently on the Généthon or Marshfield linkage maps. Recombination between proximal markers D22S270/D22S683 and D22S446/D22S311 exhibited increased rates of female meiotic recombination compared to male recombination (P < 0.01). In contrast, the region encompassing sJCW16, D22S526, D22S1743, and D22S1744 exhibited relatively greater recombination in males (1.1 cM for females and 7.5 cM for males; chi(2); P < 0.005). These four distal markers lie in a region of hyperrecombination having a sex-averaged recombination ratio of between 8.3 (D22S1843/D22S1744) and 12 cM (sJCW16/D22S526) per megabase.

Genetic analysis of brahma: the Drosophila homolog of the yeast chromatin remodeling factor SWI2/SNF2

The Drosophila brahma (brm) gene encodes an activator of homeotic genes related to the yeast chromatin remodeling factor SWI2/SNF2. Here, we report the phenotype of null and dominant-negative brm mutations. Using mosaic analysis, we found that the complete loss of brm function decreases cell viability and causes defects in the peripheral nervous system of the adult. A dominant-negative brm mutation was generated by replacing a conserved lysine in the ATP-binding site of the BRM protein with an arginine. This mutation eliminates brm function in vivo but does not affect assembly of the 2-MD BRM complex. Expression of the dominant-negative BRM protein caused peripheral nervous system defects, homeotic transformations, and decreased viability. Consistent with these findings, the BRM protein is expressed at relatively high levels in nuclei throughout the developing organism. Site-directed mutagenesis was used to investigate the functions of conserved regions of the BRM protein. Domain II is essential for brm function and is required for the assembly or stability of the BRM complex. In spite of its conservation in numerous eukaryotic regulatory proteins, the deletion of the bromodomain of the BRM protein has no discernible phenotype.

Urovirulence determinants in Escherichia coli isolates causing first-episode and recurrent cystitis in women

To assess the prevalence of urovirulence determinants among Escherichia coli isolates from women with acute uncomplicated cystitis, 121 isolates from 87 women with first-episode or recurrent cystitis and 156 fecal isolates from 52 women without recent urinary tract infection were tested using DNA probes for P fimbriae, hemolysin, aerobactin, and diffuse adhesin and for expression of hemolysin and P and F adhesins. P fimbrial genotype (P = .002), hemolysin phenotype (P = .007), and the diffuse adhesin determinant (P = .03), but not aerobactin, were found more frequently in E. coli from women with acute cystitis, and expression of the F adhesin (41%) was more common than the P adhesin (24%; P = .001). E. coli isolates that caused cystitis in women using diaphragms had fewer virulence determinants than those from nonusers (P = .04), suggesting that diaphragm use may allow infection with less virulent E. coli.

The Dr hemagglutinin, afimbrial adhesins AFA-I and AFA-III, and F1845 fimbriae of uropathogenic and diarrhea-associated Escherichia coli belong to a family of hemagglutinins with Dr receptor recognition

The receptor specificities of four Escherichia coli cloned hemagglutinins, AFA-I, AFA-III, F1845 fimbriae, and the Dr hemagglutinin were studied. Evidence is provided that all four hemagglutinins recognize as their receptor the Dr blood group antigen. However, results of experiments using enzyme-treated erythrocytes and monoclonal antibodies indicate that the four adhesins recognize different epitopes on the Dr antigen and thus constitute a family of Dr receptor-recognizing bacterial adhesins. Furthermore, the same results suggest that the Dr antigen itself may be divided into subcomponents on the basis of bacterial adhesins.

Adjuvant chemotherapy for osteosarcoma: a randomized prospective trial

To determine the role of chemotherapy in the multidisciplinary treatment of patients with osteosarcoma, a randomized prospective trial of postoperative adjuvant chemotherapy was begun in 1981. Fifty-nine patients with nonmetastatic classic intramedullary osteosarcoma were randomized; 32 received postoperative adjuvant chemotherapy consisting of high-dose methotrexate, Adriamycin (Adria Laboratories, Columbus, OH), and BCD (bleomycin, cytoxan, actinomycin D), and 27 patients received no adjuvant chemotherapy. At a median follow-up of 2 years, there was a statistically significant improvement in both disease-free and overall survival in those who received adjuvant chemotherapy. In addition, there was no difference in the less than 20% disease-free or overall survival of patients treated in the 1970s who did not receive chemotherapy, as compared with the concurrent nontreatment controls. Therefore, with identical staging procedures, uniform surgical management, and standard pathologic evaluation, postoperative adjuvant chemotherapy definitely improves disease-free and overall survival in patients with osteosarcoma.

Enhancement of the horseradish peroxidase-catalyzed chemiluminescent oxidation of cyclic diacyl hydrazides by 6-hydroxybenzothiazoles

6-Hydroxybenzothiazole, 2-cyano-6-hydroxybenzothiazole, and 2-(6-hydroxy-2-benzothiazolyl)thiazole-4-carboxylic acid (dehydroluciferin) dramatically enhance light emission from the horseradish peroxidase conjugate catalyzed oxidation of luminol, isoluminol, N-(6-aminobutyl)-N-ethyl isoluminol, and 7-dimethylaminonaphthalene-1,2-dicarboxylic acid hydrazide by either peroxide or perborate. Light emission is enhanced by up to 1000-fold, which is an improvement over the enhancement previously observed using firefly luciferin (4,5-dihydro-2-(6-hydroxy-2-benzothiazolyl)thiazole-4-carboxylic acid). Enhancement is influenced by enhancer concentration and pH. Spectral scans of light emitted in enhanced and unenhanced reactions are similar, suggesting that aminophthalate products, and not the enhancers, are the emitters.