ODP606 Long-term Efficacy of Setmelanotide in Patients With Bardet-Biedl Syndrome

Objective

Bardet-Biedl syndrome (BBS) is a rare genetic disease characterized by hyperphagia (pathologic insatiable hunger) and early-onset, severe obesity believed to be driven by impaired signaling in the melanocortin-4 receptor (MC4R) pathway. In a Phase 2 and a pivotal Phase 3 trial, treatment with the MC4R agonist setmelanotide produced beneficial reductions in weight, body mass index (BMI), BMI Z score, and hunger in patients with BBS at ∼1 year. The current analysis is the first to assess the continued long-term efficacy of setmelanotide administration in patients with BBS over ∼2 years.

Methods

Patients with BBS aged ≥6 years were eligible for this observational long-term extension (LTE) trial (NCT03651765) if they completed an index trial in which they received setmelanotide and demonstrated clinical benefit and acceptable safety as determined by the investigator. Patients received up to ∼12 months of setmelanotide as part of the index trial and began the LTE immediately following completion of the index trial. Study visits occurred approximately every 3 months in the LTE trial. Study objectives included evaluating changes in body weight and assessing safety and tolerability. The current analysis reports outcomes after ∼1 year of additional setmelanotide administration during the LTE trial, relative to index trial baseline.

Results

As of October 29, 2021, 54 patients with BBS enrolled the index trial, including 28 patients <18 years old and 26 patients ≥18 years old. Among patients who entered the LTE trial, 30 and 19 received at least 18 and 24 months of treatment, respectively. At their enrollment in their index trial, participants’ baseline mean (standard deviation [SD]) BMI was 42.2 (9.2) kg/m2, body weight in patients ≥18 years old was 132.3 (20.9) kg, and BMI Z score in patients <18 years old was 3.5 (0.76). Across age groups, after 18 and 24 months of treatment, mean (SD) percent change in BMI was −9.5% (10.5%; n=30) and −14.3% (11.6%; n=19), respectively. Mean (SD) percent change in body weight in those ≥18 years old after 18 and 24 months was −8.6% (10.3%; n=15) and −14.9% (10.4%; n=6), respectively. The mean (SD) change in BMI Z score in patients <18 years old after 18 and 24 months was −0.83 (0.50; n=13) and −0.72 (0.54; n=12), respectively. No new safety signals were observed during long-term setmelanotide administration. One patient discontinued because of an adverse event (hallucination; unlikely to be related to setmelanotide).

Conclusions

Clinically beneficial effects of setmelanotide on body weight-related measures continued to be observed in patients with BBS for up to 2 years. Only 1 patient discontinued the LTE trial due to an adverse event, suggesting setmelanotide continued to have clinical benefit and was generally well tolerated. These data support the long-term use of setmelanotide in patients with BBS.

Presentation: No date and time listed

A Phase 3 Trial in Participants With Obesity Due to Bardet-Biedl Syndrome or Alström Syndrome: Efficacy and Safety of the Melanocortin 4 Receptor Agonist Setmelanotide

Introduction: This randomized Phase 3 trial evaluated the effect of setmelanotide, a melanocortin 4 receptor agonist, on weight loss, hunger reduction, and safety outcomes in individuals (aged ≥6 years) with obesity and a genetically confirmed diagnosis of Bardet-Biedl syndrome (BBS) or Alström syndrome (AS), conditions believed to disrupt hypothalamic leptin-melanocortin signaling. Methods: For inclusion, obesity was defined as body mass index ≥30 kg/m² (in those aged ≥16 years) or weight >97th percentile (in those aged 6–15 years). Individuals were randomized and received setmelanotide or placebo for 14 weeks, followed by open-label setmelanotide so that all participants received at least 1 year of drug. Body weight, height, hunger scores, and treatment-emergent adverse events (AEs) were assessed. The primary endpoint was the proportion of participants (≥12 years) who achieved ≥10% reduction in body weight from baseline after 52 weeks of treatment. For statistical analysis, the primary endpoint had binomial proportions calculated for each of the 100 multiple imputed data sets, which were combined using Rubin’s Rule to compare against the null hypothesis with 95% confidence intervals (CIs) and P values. Efficacy analyses (including change in body weight, body mass index Z score, and hunger) were conducted in participants ≥12 years old at baseline. Safety analyses were conducted in all participants. Results: A total of 38 individuals with BBS (n=32) or AS (n=6) were enrolled. Five participants <12 years and 2 participants ≥12 years who discontinued before receiving active therapy were not included in the primary analysis. The prespecified significance cut points for the primary and key secondary endpoints were met. After ~52 weeks of setmelanotide, 34.5% (95% CI, 17.5%-51.6%; P=0.0024) of participants achieved ≥10% reduction in body weight from baseline. All observed responders had BBS. Mean ± SD percent change in body weight from baseline was −6.2% ± 8.6% (P<0.0001). In participants with BBS aged ≤17 years (n=14), mean ± SD percent change in body mass index Z score from baseline was −24.5% ± 22.3%. Mean ± SD percent Job #11307-1 1/27/2021Haws BBS AS Phase 3 ENDO 2021 EncorePage 2 change in maximal daily hunger score (based on participant responses to scoring their “most” hunger during the day) from baseline was −30.8% ± 25.0% (P<0.0001); 60.2% (95% CI, 35.3%-85.1%; P<0.0001) of participants achieved ≥25% reduction in weekly average daily hunger score from baseline. Common AEs included skin hyperpigmentation (57.9%), injection site erythema (44.7%), and nausea (34.2%). There was 1 serious treatment-related AE of anaphylactic reaction that occurred in a participant receiving placebo. Conclusions: In this Phase 3 trial in patients with BBS and AS, setmelanotide was associated with significant body weight and hunger reduction, with responses being greater in individuals with BBS.

Effect of setmelanotide, a melanocortin-4 receptor agonist, on obesity in Bardet-Biedl syndrome

AIM

To report an analysis of ~1 year of setmelanotide treatment for obesity and hunger, as well as metabolic and cardiac outcomes, in individuals with Bardet-Biedl syndrome (BBS).

MATERIALS AND METHODS

Individuals aged 12 years and older with BBS received once-daily setmelanotide. The dose was titrated every 2 weeks to establish the individual therapeutic dose (≤3 mg); treatment continued for an additional 10 weeks. Participants who lost 5 kg or more (or ≥5% of body weight if <100 kg at baseline) continued into the 52-week extension phase. The primary outcome was mean percent change from baseline in body weight at 3 months. Hunger scores and safety were secondary outcomes.

RESULTS

From February 2017 and February 2018, 10 individuals were screened; eight completed the 3-month treatment phase and seven completed the extension phase. Mean percent change in body weight from baseline to 3 months was -5.5% (90% CI, -9.3% to -1.6%; n = 8); change from baseline was -11.3% (90% CI, -15.5% to -7.0%; n = 8) at 6 months and -16.3% (90% CI, -19.9% to -12.8%; n = 7) at 12 months. All participants reported at least one treatment-emergent adverse event (AE), most commonly injection-site reaction. No AEs led to study withdrawal or death. Most, morning, and average hunger scores were reduced across time points.

CONCLUSIONS

Setmelanotide reduced body weight and hunger in individuals with BBS and had a safety profile consistent with previous reports. Setmelanotide may be a treatment option in individuals with BBS-associated obesity and hyperphagia.

Prevalence estimation for monogenic autosomal recessive diseases using population-based genetic data

Genetic methods can complement epidemiological surveys and clinical registries in determining prevalence of monogenic autosomal recessive diseases. Several large population-based genetic databases, such as the NHLBI GO Exome Sequencing Project, are now publically available. By assuming Hardy-Weinberg equilibrium, the frequency of individuals homozygous in the general population for a particular pathogenic allele can be directly calculated from a sample of chromosomes where some harbor the pathogenic allele. Further assuming that the penetrance of the pathogenic allele(s) is known, the prevalence of recessive phenotypes can be determined. Such work can inform public health efforts for rare recessive diseases. A Bayesian estimation procedure has yet to be applied to the problem of estimating disease prevalence from large population-based genetic data. A Bayesian framework is developed to derive the posterior probability density of monogenic, autosomal recessive phenotypes. Explicit equations are presented for the credible intervals of these disease prevalence estimates. A primary impediment to performing accurate disease prevalence calculations is the determination of truly pathogenic alleles. This issue is discussed, but in many instances remains a significant barrier to investigations solely reliant on statistical interrogation--functional studies can provide important information for solidifying evidence of variant pathogenicity. We also discuss several challenges to these efforts, including the population structure in the sample of chromosomes, the treatment of allelic heterogeneity, and reduced penetrance of pathogenic variants. To illustrate the application of these methods, we utilized recently published genetic data collected on a large sample from the Schmiedeleut Hutterites. We estimate prevalence and calculate 95% credible intervals for 13 autosomal recessive diseases using these data. In addition, the Bayesian estimation procedure is applied to data from a central European study of hereditary fructose intolerance. The methods described herein show a viable path to robustly estimating both the expected prevalence of autosomal recessive phenotypes and corresponding credible intervals using population-based genetic databases that have recently become available. As these genetic databases increase in number and size with the advent of cost-effective next-generation sequencing, we anticipate that these methods and approaches may be helpful in recessive disease prevalence calculations, potentially impacting public health management, health economic analyses, and treatment of rare diseases.

Autosomal Dominant Pseudohypoaldosteronism Type 1: Mechanisms, Evidence for Neonatal Lethality, and Phenotypic Expression in Adults

Autosomal dominant pseudohypoaldosteronism type 1 (adPHA1) is a rare condition that is characterized by renal resistance to aldosterone, with salt wasting, hyperkalemia, and metabolic acidosis. It is thought of as a mild disorder; affected children's symptoms respond promptly to salt therapy, and treatment is not required after childhood. Mutations in the mineralocorticoid receptor gene (MR) cause adPHA1, but the long-term consequences of MR deficiency in humans are not known. Herein are described six novel adPHA1-causing MR mutations (four de novo) and evidence that haploinsufficiency of MR is sufficient to cause adPHA1. Furthermore, genotype-phenotype correlation is reported in a large adPHA1 kindred. A number of cases of neonatal mortality in infants who were at risk for adPHA1 were identified; coupled with the frequent identification of de novo mutations in affected individuals, this suggests that the seemingly benign adPHA1 may have been a fatal neonatal disorder in previous eras, preventing propagation of disease alleles. In contrast, it is shown that adult patients with adPHA1 are clinically indistinguishable from their wild-type relatives except for presumably lifelong elevation of renin, angiotensin II, and aldosterone levels. These data highlight the critical role of MR in the maintenance of salt homeostasis early in life and illuminate the sodium dependence of pathologic effects of renin and angiotensin II. They furthermore argue that nongenomic effects of aldosterone play no significant role in the long-term development of cardiovascular disease.

Rapidly progressive T cell lymphoma presenting as acute renal failure: case report and review of the literature

We describe a case of peripheral T cell lymphoma that is remarkable for its fulminate course and selective targeting of both kidneys. The patient was a 6-year-old girl who was in her usual state of good health until the onset of abdominal pain and fever. She was treated for acute oliguric renal failure and visual disturbances. A renal biopsy was performed. Biopsy findings were interpreted as suggestive of a vasculitic process, and treatment was initiated for a presumptive diagnosis of Wegener's granulomatosis. The patient died 3 days following admission, and autopsy revealed extensive bilateral kidney infiltration by a peripheral T cell lymphoma. The remainder of the body was spared with the exception of mild infiltration of the pulmonary parenchyma and choroid plexus by neoplastic lymphocytes. The neoplastic nature of the disease was confirmed utilizing immunoperoxidase stains and T cell receptor gene rearrangement. Primary renal lymphoma and renal failure attributable to involvement by lymphoma are rare findings that should be considered when other more common causes of renal insufficiency have been excluded. The presenting clinical complaints are generally of short duration, nonspecific, and atypical. Most patients exhibit oliguria. Physical examination may reveal hepatosplenomegaly, lymphadenopathy, and flank and/or abdominal mass(es). Laboratory findings frequently include an elevated serum creatinine, blood urea nitrogen, lactate dehydrogenase, and a mild proteinuria. Electrolyte abnormalities are variably present. Possible radiographic findings include hypodense or hypoechoic renal lesions and diffuse bilateral renal enlargement. Although the prognosis is dismal, survival may be prolonged utilizing current treatment modalities, and rare patients may be "cured" of disease. The clinical presentation, radiological findings, and prognosis of patients with clinically evident renal involvement by non-Hodgkin's lymphoma are discussed.

Rapidly progressive T cell lymphoma presenting as acute renal failure: case report and review of the literature

We describe a case of peripheral T cell lymphoma that is remarkable for its fulminate course and selective targeting of both kidneys. The patient was a 6-year-old girl who was in her usual state of good health until the onset of abdominal pain and fever. She was treated for acute oliguric renal failure and visual disturbances. A renal biopsy was performed. Biopsy findings were interpreted as suggestive of a vasculitic process, and treatment was initiated for a presumptive diagnosis of Wegener's granulomatosis. The patient died 3 days following admission, and autopsy revealed extensive bilateral kidney infiltration by a peripheral T cell lymphoma. The remainder of the body was spared with the exception of mild infiltration of the pulmonary parenchyma and choroid plexus by neoplastic lymphocytes. The neoplastic nature of the disease was confirmed utilizing immunoperoxidase stains and T cell receptor gene rearrangement. Primary renal lymphoma and renal failure attributable to involvement by lymphoma are rare findings that should be considered when other more common causes of renal insufficiency have been excluded. The presenting clinical complaints are generally of short duration, nonspecific, and atypical. Most patients exhibit oliguria. Physical examination may reveal hepatosplenomegaly, lymphadenopathy, and flank and/or abdominal mass(es). Laboratory findings frequently include an elevated serum creatinine, blood urea nitrogen, lactate dehydrogenase, and a mild proteinuria. Electrolyte abnormalities are variably present. Possible radiographic findings include hypodense or hypoechoic renal lesions and diffuse bilateral renal enlargement. Although the prognosis is dismal, survival may be prolonged utilizing current treatment modalities, and rare patients may be "cured" of disease. The clinical presentation, radiological findings, and prognosis of patients with clinically evident renal involvement by non-Hodgkin's lymphoma are discussed.