Infusion-associated Reactions Research Articles

High antibody titer in an adult with Pompe disease affects treatment with alglucosidase alfa

Clinical trials have demonstrated beneficial effects of enzyme replacement therapy (ERT) with alglucosidase alfa in infants, children and adults with Pompe disease. Recent studies have shown that high antibody titers can occur in patients receiving ERT and counteract the effect of treatment. This particularly occurs in those patients with classic-infantile Pompe disease that do not produce any endogenous acid α-glucosidase (CRIM-negative). It is still unclear to what extent antibody formation affects the outcome of ERT in adults with residual enzyme activity. We present the case of a patient with adult-onset Pompe disease. He was diagnosed at the age of 39 years by enzymatic testing (10.7% residual activity in fibroblasts) and DNA analysis (genotype: c.-32-13T>G/p.Trp516X). Infusion-associated reactions occurred during ERT and the patient's disease progressed. Concurrently, the antibody titer rose to a similarly high level as reported for some CRIM-negative patients with classic-infantile Pompe disease. Using newly developed immunologic-assays we could calculate that approximately 40% of the administered alglucosidase alfa was captured by circulating antibodies. Further, we could demonstrate that uptake of alglucosidase alfa by cultured fibroblasts was inhibited by admixture of the patient's serum. This case demonstrates that also patients with an appreciable amount of properly folded and catalytically active endogenous acid α-glucosidase can develop antibodies against alglucosidase alfa that affect the response to ERT.

Thrombocytopenia associated with galsulfase treatment

Mucopolysaccharidosis type VI (MPS VI), or Maroteaux-Lamy syndrome, is a lysosomal storage disorder that results from a deficiency of the enzyme N-acetylgalactosamine-4-sulfatase or arylsulfatase B (ASB). It is a relatively rare disorder, with an estimated incidence of 1 in 248,000 to 1 in 300,000. The diagnosis is made on the basis of findings of elevated urine glycosaminoglycans and a deficiency of ASB activity in leukocytes or cultured fibroblasts. In treatment of MPS VI, enzyme replacement therapy (galsulfase; human recombinant ASB enzyme) became available. Infusions of galsulfase were generally well tolerated. But in some patients, infusion-associated reactions including rash, urticaria, headache, hypotension, nausea, and vomiting were documented and were managed successfully by interrupting or slowing the rate of infusion and/or by the administration of antihistamines, antipyretics, corticosteroids, or oxygen. Here, we report a case with MPS VI who developed thrombocytopenia after third dose of therapy. To the best of our knowledge, this is the first report about thrombocytopenia associated with galsulfase therapy in the literature. Additionally, with this report, we want to share our approach for this case.

A Randomized Study of Alglucosidase Alfa in Late-Onset Pompe's Disease

Pompe's disease is a metabolic myopathy caused by a deficiency of acid alpha glucosidase (GAA), an enzyme that degrades lysosomal glycogen. Late-onset Pompe's disease is characterized by progressive muscle weakness and loss of respiratory function, leading to early death. We conducted a randomized, placebo-controlled trial of alglucosidase alfa, a recombinant human GAA, for the treatment of late-onset Pompe's disease. Ninety patients who were 8 years of age or older, ambulatory, and free of invasive ventilation were randomly assigned to receive biweekly intravenous alglucosidase alfa (20 mg per kilogram of body weight) or placebo for 78 weeks at eight centers in the United States and Europe. The two primary end points were distance walked during a 6-minute walk test and percentage of predicted forced vital capacity (FVC). At 78 weeks, the estimated mean changes from baseline in the primary end points favored alglucosidase alfa (an increase of 28.1+/-13.1 m on the 6-minute walk test and an absolute increase of 3.4+/-1.2 percentage points in FVC; P=0.03 and P=0.006, respectively). Similar proportions of patients in the two groups had adverse events, serious adverse events, and infusion-associated reactions; events that occurred only in patients who received the active study drug included anaphylactic reactions and infusion-associated reactions of urticaria, flushing, hyperhidrosis, chest discomfort, vomiting, and increased blood pressure (each of which occurred in 5 to 8% of the patients). In this study population, treatment with alglucosidase alfa was associated with improved walking distance and stabilization of pulmonary function over an 18-month period. (ClinicalTrials.gov number, NCT00158600.)

Clinical outcomes after long-term treatment with alglucosidase alfa in infants and children with advanced Pompe disease

PurposeA clinical trial was conducted to evaluate the safety and efficacy of alglucosidase alfa in infants and children with advanced Pompe disease. MethodsOpen-label, multicenter study of IV alglucosidase alfa treatment in 21 infants 3–43 months old (median 13 months) with minimal acid α-glucosidase activity and abnormal left ventricular mass index by echocardiography. Patients received IV alglucosidase alfa every 2 weeks for up to 168 weeks (median 120 weeks). Survival results were compared with an untreated reference cohort. ResultsAt study end, 71% (15/21) of patients were alive and 44% (7/16) of invasive-ventilator free patients remained so. Compared with the untreated reference cohort, alglucosidase alfa reduced the risk of death by 79% (P < 0.001) and the risk of invasive ventilation by 58% (P = 0.02). Left ventricular mass index improved or remained normal in all patients evaluated beyond 12 weeks; 62% (13/21) achieved new motor milestones. Five patients were walking independently at the end of the study and 86% (18/21) gained functional independence skills. Overall, 52% (11/21) of patients experienced infusion-associated reactions; 95% (19/20) developed IgG antibodies to recombinant human lysosomal acid α-glucosidase; no patients withdrew from the study because of safety concerns. ConclusionsIn this population of infants with advanced disease, biweekly infusions with alglucosidase alfa prolonged survival and invasive ventilation-free survival. Treatment also improved indices of cardiomyopathy, motor skills, and functional independence.

Long-term Efficacy and Safety of Laronidase in the Treatment of Mucopolysaccharidosis I

Our goal was to evaluate the long-term safety and efficacy of recombinant human alpha-l-iduronidase (laronidase) in patients with mucopolysaccharidosis I. All 45 patients who completed a 26-week, double-blind, placebo-controlled trial of laronidase were enrolled in a 3.5-year open-label extension study. Mean patient age at baseline was 16 (range: 6-43) years. All patients had attenuated disease (84% Hurler-Scheie, 16% Scheie phenotypes). Clinical, biochemical, and health outcomes measures were evaluated through the extension phase. Changes are presented as the mean +/- SEM. All 40 patients (89%) who completed the trial received at least 80% of scheduled infusions. As shown in earlier trials, urinary glycosaminoglycan levels decreased within the first 12 weeks and liver volume decreased within the first year. Percent predicted forced vital capacity remained stable, with a linear slope of -0.78 percentage points per year. The 6-minute walk distance increased 31.7 +/- 10.2 m in the first 2 years, with a final gain of 17.1 +/- 16.8 m. Improvements in the apnea/hypopnea index (decrease of 7.6 +/- 4.5 events per hour among the patients with significant baseline sleep apnea) and shoulder flexion (increase of 17.4 degrees +/- 3.6 degrees) were most rapid during the first 2 years. Improvements in the Child Health Assessment Questionnaire/Health Assessment Questionnaire disability index (decrease of 0.31 +/- 0.11, signifying a clinically meaningful improvement in activities of daily living) were gradual and sustained over the treatment period. Laronidase infusions were generally well tolerated except in 1 patient who experienced an anaphylactic reaction. Infusion-associated reactions, which occurred in 53% of the patients, were mostly mild, easily managed, and decreased markedly after 6 months. One patient died as a result of an upper respiratory infection unrelated to treatment. Antibodies to laronidase developed in 93% of the patients; 29% of the patients were seronegative at their last assessment. This trial demonstrates the long-term clinical benefit and safety of laronidase in attenuated patients with mucopolysaccharidosis I and highlights the magnitude and chronology of treatment effects. Prompt diagnosis and early treatment will maximize treatment outcomes.

A dose-optimization trial of laronidase (Aldurazyme ®) in patients with mucopolysaccharidosis I

Recombinant human α- l-iduronidase (Aldurazyme ®, laronidase) is approved as an enzyme replacement therapy to treat the lysosomal storage disorder, mucopolysaccharidosis type I (MPS I) at a dose of 0.58 mg/kg by once-weekly intravenous infusion. To assess whether alternate dosing regimens might provide a better reduction in lysosomal storage, a 26-week, randomized, open-label, multinational dose-optimization trial was conducted. The pharmacodynamic effect and safety of the approved laronidase dose was compared to three alternative regimens (1.2 mg/kg every 2 weeks; 1.2 mg/kg every week; 1.8 mg/kg every 2 weeks) among 33 MPS I patients. The four treatment regimens showed no significant differences in the reduction of urinary glycosaminoglycan excretion or liver volume. Laronidase had an acceptable safety profile in all dose regimen groups. Infusion-associated reactions were the most common drug-related adverse events across dose regimens (by patient incidence), and included pyrexia (21%), vomiting (15%), rash (15%), and urticaria (12%). Patients in the approved dose group had the lowest incidence of drug-related adverse events (38% vs. 63–75%) and infusion-associated reactions (25% vs. 25–63%). There was one death: a patient with acute bronchitis died of respiratory failure 6 h after completing the first laronidase infusion. The approved 0.58 mg/kg/week laronidase dose regimen provided near-maximal reductions in glycosaminoglycan storage and the best benefit-to-risk ratio. The 1.2 mg/kg every 2 weeks regimen may be an acceptable alternative for patients with difficulty receiving weekly infusions, but the long-term effects of this regimen are unknown.

Home treatment with Elaprase® and Naglazyme® is safe in patients with mucopolysaccharidoses types II and VI, respectively

Enzyme replacement therapy for lysosomal storage disorders has made an important contribution to improving the quality of life of affected patients. The treatment, however, is invasive and onerous, involving weekly or biweekly intravenous infusions of product over a 3-4 h period. Such therapy can be extremely disruptive of normal family life and the provision of a safe, home treatment regimen is greatly appreciated by affected families. In this report we demonstrate the safety of home treatment with Elaprase for mucopolysaccharidosis type II (17 patients) and Naglazyme for mucopolysaccharidosis type VI (6 patients). Careful patient selection, an experienced home care company and a detailed management plan for potential anaphylaxis and infusion-associated reactions are important components in a successful home treatment programme.

Successful reinstitution of agalsidase beta therapy in Fabry disease patients with previous IgE-antibody or skin-test reactivity to the recombinant enzyme

PurposeTo determine if enzyme replacement therapy, involving intravenous infusions of recombinant human α-galactosidase A (agalsidase beta; Fabrazyme®), could be safely continued in patients with Fabry disease who had been withdrawn from a previous clinical trial as a precautionary, protocol-specified measure due to detection of serum IgE antibodies or skin-test reactivity to agalsidase beta. MethodsThe rechallenge infusion protocol specified strict patient monitoring conditions and graded dosing and infusion-rate schemes that were adjusted according to each patient's tolerance to the infusion. Six males (age: 26–66 years) were enrolled. ResultsDuring rechallenge, five patients received between 4 and 27 infusions; one patient voluntarily withdrew after one infusion because of recurrence of infusion-associated reactions. No anaphylactic reactions occurred. All adverse events, including four serious adverse events, were mild or moderate in intensity. Most treatment-related adverse events occurred during infusions (most commonly urticaria, vomiting, nausea, chills, pruritus, hypertension) and were resolved by infusion rate reductions and/or medication. After participation in the study, all patients, including the one who withdrew after one infusion, transitioned to commercial drug. ConclusionsAgalsidase beta therapy can be successfully reinstated in patients with Fabry disease who have developed IgE antibodies or skin test reactivity to the recombinant enzyme.

Safety of Biologic Therapy in Rheumatoid Arthritis and Other Autoimmune Diseases: Focus on Rituximab

To review the safety of biologic agents used to treat rheumatoid arthritis (RA) and other autoimmune diseases, with a focus on rituximab. Information was gathered from a search of the PubMed database and from major congress abstract listings through June 2007. Rituximab is approved for treating RA in patients with an inadequate response to TNF inhibitors and is under study in other indications for RA and other autoimmune disorders. The current safety profile of rituximab in RA is known from Phase II and III studies conducted preapproval, treating approximately 750 patients, as well as from long-term extension studies with repeated therapy. Clinical trials have established that the most common adverse events are infusion-associated reactions, seen in 29 to 40% of patients, most of which are mild to moderate and occur following the first rituximab infusion, with incidence and severity decreasing with subsequent infusions. Rates of infections and serious infections to date are within the range expected for RA patients treated with other biologic agents, but the longer term effects of B-cell depletion and the effects of repeated treatment on the risk of infections are uncertain. Information is limited for rituximab safety in other autoimmune disorders but current data do not suggest that there is a significant difference in adverse events from that previously reported. Rituximab is an important addition to the rheumatologist's armamentarium for the treatment of difficult RA and ongoing trials will determine its utility in other indications for RA and other autoimmune conditions. The true safety profile of rituximab will emerge as larger numbers of patients are treated in routine clinical practice.

Successful Management of Difficult Infusion-Associated Reactions in a Young Patient With Mucopolysaccharidosis Type VI Receiving Recombinant Human Arylsulfatase B (Galsulfase [Naglazyme

Our patient with mucopolysaccharidosis type VI received enzyme replacement therapy with recombinant human arylsulfatase B (galsulfase [Naglazyme, BioMarin Pharmaceutical Inc, Novato, CA]) shortly after approval by the US Food and Drug Administration. After 1 month of weekly infusions, the patient developed significant infusion-associated reactions and could not tolerate therapy at the recommended infusion rate. We were able to continue treatment successfully by the addition of steroids to the premedication regimen and by significantly reducing the rate of drug infusion. Over the next several months, the patient's infusion rate was slowly increased and the premedications were weaned. We demonstrate that by significantly reducing the rate of infusions and adjusting the premedication regimen, galsulfase infusions can continue with no additional observance of infusion-associated reactions.

Safety and Efficacy of Enzyme Replacement Therapy with Agalsidase Beta: An International, Open-label Study in Pediatric Patients with Fabry Disease

To evaluate the safety and explore the efficacy of enzyme replacement therapy with agalsidase beta (recombinant human alpha-galactosidase A; Fabrazyme [Genzyme Corporation, Cambridge, MA]) in pediatric patients with Fabry disease, a genetic disorder in which deficient endogenous enzyme causes pathogenic tissue accumulation of globotriaosylceramide (GL-3). Fourteen male and 2 female patients, 8 to 16 years old, were treated in this open-label study. A 12-week observation period to collect baseline data preceded the 48-week treatment period when agalsidase beta (1 mg/kg) was infused intravenously every 2 weeks. No primary efficacy end point was specified. Before treatment, results of skin biopsies from 12 male patients showed moderate or severe GL-3 accumulation in superficial dermal capillary endothelial cells; with treatment, these cells were completely cleared of GL-3 in week-24 biopsies from all 12 male patients and in all available week-48 biopsies. With treatment, reports of gastrointestinal symptoms declined steadily. Patient diaries documented significant reductions in school absences due to sickness. Agalsidase beta was generally well tolerated; most treatment-related adverse events were mild or moderate infusion-associated reactions involving rigors, fever, or rhinitis. Agalsidase beta safely and effectively reduced the GL-3 accumulation in dermal endothelium already evident in children with Fabry disease. Early intervention may prevent irreversible end-organ damage from chronic GL-3 deposition.

Home treatment with enzyme replacement therapy for mucopolysaccharidosis type I is feasible and safe

Intravenous enzyme replacement therapy (ERT) with recombinant alpha-L-iduronidase may ameliorate the non-neurological symptoms in patients with mucopolysaccharidosis type I (MPS I). Since home-based ERT for Gaucher and Fabry diseases has been reported to be safe and successful, we investigated the feasibility and safety of home therapy in patients with MPS I. This two-centre study included 17 ERT-treated MPS I patients between 1 and 35 years of age. A patient was allowed to transfer to home treatment after a minimum period of 6 months of in-hospital administration of ERT and after a self- or home nurse-supported home setting was arranged. Thirteen out of 17 patients transferred to home treatment with a median time to transfer of 13 months (range 7-40 months). Two patients preferred to continue ERT in the hospital, whereas for two other patients the transfer to home was hampered for practical reasons. All patients who received ERT at home were assisted by either a relative or a nurse. In total over 1000 home infusions were performed and no serious complications were observed. Two infusion-associated reactions were observed, both within the first 3 months of in-hospital administration of ERT. All patients except one developed antibodies against the recombinant enzyme, but this was not associated with the development of hypersensitivity reactions. ERT for MPS I applied at home is safe and might alleviate the burden of life-long intravenous treatment in these patients.

Amphotericin B Treatment for Indian Visceral Leishmaniasis: Response to 15 Daily versus Alternate-Day Infusions

For patients with Indian visceral leishmaniasis, amphotericin B deoxycholate is usually given as 15 alternate-day infusions of 1 mg/kg over 30 days (total dose, 15 mg/kg); daily treatment with 1 mg/kg for 20 days (total dose, 20 mg/kg) is also used. This study was done to address the unsettled therapeutic questions of administration schedule (alternate-day vs. daily administration) and dose (1 vs. 0.75 mg/kg) and to determine whether the duration of amphotericin B treatment in Bihar, India, can be shortened to 15 days. To compare alternate-day versus daily administration and 1-mg/kg versus 0.75-mg/kg doses and to determine whether the duration of treatment could be abbreviated, Indian subjects randomly received 15 infusions of 1 mg/kg (group A; 245 patients) or 0.75 mg/kg (group B; 244 patients) on alternate days or 1 mg/kg (group C; 500 patients) or 0.75 mg/kg (group D; 496 patients) daily. Noninferiority testing compared 6-month cure rates using a 5% margin. Overall, 1439 of the 1485 subjects completed treatment and responded. Treatment interruptions (nephrotoxicity) but not infusion-associated reactions or study removals were more common with daily administration. Final cure rates at 6 months were similar: group A, 234 patients (96%; 95% confidence interval [CI], 92%-98%); group B, 225 patients (92%; 95% CI, 88%-95%); group C, 483 patients (97%; 95% CI, 95%-98%); and group D, 476 patients (96%; 95% CI, 94%-97%; P>.05). Provided that the serum creatinine level is repeated once, daily treatment with amphotericin B, 0.75 mg/kg for 15 days (total dose, 11.25 mg/kg), is efficient and effective for visceral leishmaniasis in India. ClinicalTrials.gov identifier: NCT00310505.

Sustained, Long-Term Renal Stabilization After 54 Months of Agalsidase β Therapy in Patients with Fabry Disease

Fabry disease, an inherited deficiency of the lysosomal enzyme alpha-galactosidase A, causes progressive intralysosomal accumulation of globotriaosylceramide (GL-3) and premature death from renal, cardiac, and cerebrovascular manifestations. To determine the long-term safety and efficacy of recombinant human alpha-galactosidase A, an open-label, phase III extension study was conducted, involving 58 patients who had classic Fabry disease and completed a 20-wk, double-blind, randomized, placebo-controlled, phase III study of agalsidase beta and were transitioned to an extension trial to receive biweekly 1 mg/kg agalsidase beta for up to an additional 54 mo. GL-3 accumulation was evaluated in the capillary endothelia of the skin, kidney, and heart. Renal function was assessed. By month 54, all patients with optional kidney biopsies (n = 8) maintained complete GL-3 clearance in renal capillary endothelial cells and multiple cell types. Continued, complete clearance of skin (31 of 36) and heart (six of eight) capillary endothelium was demonstrated. Mean plasma GL-3 levels remained decreased in the normal range. Median serum creatinine and estimated GFR remained stable (normal) in patients with renal data at month 54 (n = 41). Six patients had renal disease progression; most (four of six) were older than 40 yr and had significant proteinuria at baseline and evidence of sclerotic glomeruli pretreatment. Adverse events were generally mild and unrelated to treatment. The most common treatment-related adverse events were infusion-associated reactions, which decreased over time. Long-term agalsidase beta therapy stabilizes renal function in patients without renal involvement at baseline, maintains reduction of plasma GL-3, and sustains GL-3 clearance in capillary endothelial cells and multiple renal cell types.

Agalsidase-Beta Therapy for Advanced Fabry Disease

Fabry disease (alpha-galactosidase A deficiency) is a rare, X-linked lysosomal storage disorder that can cause early death from renal, cardiac, and cerebrovascular involvement. To see whether agalsidase beta delays the onset of a composite clinical outcome of renal, cardiovascular, and cerebrovascular events and death in patients with advanced Fabry disease. Randomized (2:1 treatment-to-placebo randomization), double-blind, placebo-controlled trial. 41 referral centers in 9 countries. 82 adults with mild to moderate kidney disease; 74 of whom were protocol-adherent. Intravenous infusion of agalsidase beta (1 mg per kg of body weight) or placebo every 2 weeks for up to 35 months (median, 18.5 months). The primary end point was the time to first clinical event (renal, cardiac, or cerebrovascular event or death). Six patients withdrew before reaching an end point: 3 to receive commercial therapy and 3 due to positive or inconclusive serum IgE or skin test results. Three patients assigned to agalsidase beta elected to transition to open-label treatment before reaching an end point. Thirteen (42%) of the 31 patients in the placebo group and 14 (27%) of the 51 patients in the agalsidase-beta group experienced clinical events. Primary intention-to-treat analysis that adjusted for an imbalance in baseline proteinuria showed that, compared with placebo, agalsidase beta delayed the time to first clinical event (hazard ratio, 0.47 [95% CI, 0.21 to 1.03]; P = 0.06). Secondary analyses of protocol-adherent patients showed similar results (hazard ratio, 0.39 [CI, 0.16 to 0.93]; P = 0.034). Ancillary subgroup analyses found larger treatment effects in patients with baseline estimated glomerular filtration rates greater than 55 mL/min per 1.73 m2 (hazard ratio, 0.19 [CI, 0.05 to 0.82]; P = 0.025) compared with 55 mL/min per 1.73 m2 or less (hazard ratio, 0.85 [CI, 0.32 to 2.3]; P = 0.75) (formal test for interaction, P = 0.09). Most treatment-related adverse events were mild or moderate infusion-associated reactions, reported by 55% of patients in the agalsidase-beta group and 23% of patients in the placebo group. The study sample was small. Only one third of the patients experienced clinical events, and some patients withdrew before experiencing any event. Agalsidase-beta therapy slowed progression to the composite clinical outcome of renal, cardiac, and cerebrovascular complications and death compared with placebo in patients with advanced Fabry disease. Therapeutic intervention before irreversible organ damage may provide greater clinical benefit.

Recombinant human acid α-glucosidase

Pompe disease is a progressive metabolic neuromuscular disorder resulting from deficiency of lysosomal acid alpha-glucosidase (GAA). Infantile-onset Pompe disease is characterized by cardiomyopathy, respiratory and skeletal muscle weakness, and early death. The safety and efficacy of recombinant human (rh) GAA were evaluated in 18 patients with rapidly progressing infantile-onset Pompe disease. Patients were diagnosed at 6 months of age and younger and exhibited severe GAA deficiency and cardiomyopathy. Patients received IV infusions of rhGAA at 20 mg/kg (n = 9) or 40 mg/kg (n = 9) every other week. Analyses were performed 52 weeks after the last patient was randomized to treatment. All patients (100%) survived to 18 months of age. A Cox proportional hazards analysis demonstrated that treatment reduced the risk of death by 99%, reduced the risk of death or invasive ventilation by 92%, and reduced the risk of death or any type of ventilation by 88%, as compared to an untreated historical control group. There was no clear advantage of the 40-mg/kg dose with regard to efficacy. Eleven of the 18 patients experienced 164 infusion-associated reactions; all were mild or moderate in intensity. Recombinant human acid alpha-glucosidase is safe and effective for treatment of infantile-onset Pompe disease. Eleven patients experienced adverse events related to treatment, but none discontinued. The young age at which these patients initiated therapy may have contributed to their improved response compared to previous trials with recombinant human acid alpha-glucosidase in which patients were older.

The long-term international safety experience of imiglucerase therapy for Gaucher disease

Background Gaucher disease is a lysosomal storage disorder resulting from a deficiency of the lysosomal enzyme glucocerebrosidase. Since approval by the FDA in 1994 and EMEA in 1997, enzyme replacement therapy with Cerezyme ® (imiglucerase for injection) has been the standard of care for the treatment of Gaucher disease. Objective To review the long-term international safety experience of imiglucerase from 1994 through 2004. Materials and methods All spontaneous adverse event reports captured in the pharmacovigilance database for imiglucerase from 1994 through 2004 were analyzed. All adverse events were classified using the current version of the Medical Dictionary for Regulatory Activities (MedDRA). Patients without prior exposure to imiglucerase from 1994 through 2005 were assessed for the development of antibodies to imiglucerase as detected by enzyme-linked immunosorbant and radioimmunoprecipitation assays. Results Analysis of the long-term safety experience with imiglucerase therapy demonstrates a stable and low rate of adverse events and seroconversion from 1994 through 2005. The majority of frequently reported adverse events related to imiglucerase were infusion-associated reactions which were predominantly self-limiting in nature and did not require discontinuation of treatment. Between 1994 and 2005, IgG antibodies to imiglucerase were detected in approximately 15% of treatment-naïve patients. Conclusions The long-term stability of reported events and seroconversion is a reflection of a well-characterized cell expression system and a mature quality-controlled manufacturing process. Imiglucerase is a safe therapy for the treatment of Gaucher disease with a stable and low rate of reported adverse events and seroconversion.

169 Update on Enzyme Replacement Therapy (ERT) with Recombinant Human Arylsulfatase B (RHASB) for MPS VI (Maroteaux-Lamy)

MPS VI is a rare, life-threatening lysosomal storage disease with no effective treatment. ERT with rhASB has shown promising results in 2 clinical studies. The objective of this Phase 3 study was to confirm efficacy and safety. 39 patients were enrolled in a randomized, double-blind, placebo-controlled study for 24 weeks. The primary endpoint was the distance walked in 12 minutes (12MWT), while secondary endpoints were the number of stairs climbed in 3 minutes (3MSC), and the level of urinary glycosaminoglycans (GAGs). After 24 weeks, all patients received drug in a 24 week open label extension period. For the Week 1–24 period, the 19 patients receiving rhASB demonstrated a significant mean improvement of 92 meters (m) in the 12MWT as compared to the 20 patients receiving placebo (p=0.025). For the weeks 25 to 48 period, the placebo group, now receiving rhASB, showed a mean increase of 65 m relative to Week 24 (p=0.007). The original rhASB group continuing on treatment during this period improved their mean walk distance an additional 36 m (p=0.15). For the 3MSC, the rhASB group demonstrated a mean improvement of 5.7 stairs/minute after 24 weeks as compared to the placebo group (p=0.053). Relative to 12MWT, similar improvements in 3MSC were observed for each group from Week 24 to Week 48. Upon receiving rhASB, both the rhASB and placebo groups had rapid declines in urinary GAGs (p<0.001). Infusions were generally well tolerated: 98% of possible infusions were received. The majority of adverse events were mild to moderate in severity. All but one patient developed IgG antibodies to rhASB, but these antibodies were not associated with infusion-associated reactions or lack of clinical benefit. rhASB improves physical mobility and endurance, reduces GAGs, and has an acceptable safety profile. Sponsor: BioMarin Pharmaceutical Inc.

The Role of Radioimmunotherapy with Yttrium-90 Ibritumomab Tiuxetan in the Treatment of Non-Hodgkin Lymphoma

Radioimmunotherapy (RIT) is among the newest modalities for treating the diverse neoplasms known as non-Hodgkin lymphomas (NHLs). The first RIT agent approved by the US FDA was yttrium-90 (90Y) ibritumomab tiuxetan in February 2002. This radioimmunoconjugate consists of the monoclonal IgG1 antibody ibritumomab (the murine parent of rituximab) bound to the chelator tiuxetan and linked by a stable thiourea covalent bond to the beta-emitting radionuclide 90Y. RIT with 90Y ibritumomab tiuxetan is completed in 7-9 days on an outpatient basis, with only minimal (universal) precautions required. The dosing of 90Y ibritumomab tiuxetan is based on patient weight and platelet count, after normal biodistribution with indium-111 ibritumomab tiuxetan has been confirmed. Treatment with 90Y ibritumomab tiuxetan has produced high response rates and long-term benefits in patients with relapsed or refractory follicular and low-grade NHL, including those in whom rituximab therapy has failed. Its toxicity is primarily hematologic, with the hematologic nadirs generally occurring at 7-9 weeks after treatment. Severe infections are uncommon, with infrequent need for supportive measures such as administration of growth factors and transfusions of blood components. There is little nonhematologic toxicity with RIT and it is generally related to infusion-associated reactions. Clinical trials are investigating ways of increasing the efficacy of RIT. In particular, using RIT earlier in the course of treatment of NHL appears to be a promising approach and has been shown to produce better results than when it is used later. Ongoing research is needed to maximize the efficacy of RIT and minimize adverse events, with the goal of developing a multimodality approach that combines RIT with other biologic agents and possibly chemotherapy as frontline treatment to improve the outcomes in patients with NHL.

Long-Term Safety and Efficacy of Enzyme Replacement Therapyfor Fabry Disease

Elsewhere, we reported the safety and efficacy results of a multicenter phase 3 trial of recombinant human alpha -galactosidase A (rh-alpha GalA) replacement in patients with Fabry disease. All 58 patients who were enrolled in the 20-wk phase 3 double-blind, randomized, and placebo-controlled study received subsequently 1 mg/kg of rh-alpha GalA (agalsidase beta, Fabrazyme, Genzyme Corporation) biweekly in an ongoing open-label extension study. Evidence of long-term efficacy, even in patients who developed IgG antibodies against rh- alpha GalA, included the continuously normal mean plasma globotriaosylceramide (GL-3) levels during 30 mo of the extension study and the sustained capillary endothelial GL-3 clearance in 98% (39/40) of patients who had a skin biopsy taken after treatment for 30 mo (original placebo group) or 36 mo (original enzyme-treated group). The mean serum creatinine level and estimated glomerular filtration rate also remained stable after 30-36 mo of treatment. Infusion-associated reactions decreased over time, as did anti-rh- alpha GalA IgG antibody titers. Among seroconverted patients, after 30-36 mo of treatment, seven patients tolerized (no detectable IgG antibody), and 59% had > or =4-fold reductions in antibody titers. As of 30 mo into the extension trial, three patients were withdrawn from the study because of positive serum IgE or skin tests; however, all have been rechallenged successfully at the time of this report. Thus, enzyme replacement therapy for 30-36 mo with agalsidase beta resulted in continuously decreased plasma GL-3 levels, sustained endothelial GL-3 clearance, stable kidney function, and a favorable safety profile.