RF26 | PMON332 Safety and Efficacy of Treatment with Lonapegsomatropin in Children with Growth Hormone Deficiency at Week 130 in the enliGHten Trial

Background

Once-weekly lonapegsomatropin (TransCon hGH) is a long-acting prodrug of somatropin, recently approved for the treatment of pediatric growth hormone deficiency (GHD) by the US FDA. In the pivotal 52-week phase 3 heiGHt trial and the 26-week fliGHt trial, lonapegsomatropin demonstrated safety and efficacy in both treatment-naïve and treatment-experienced children with GHD.

Methods

Results are reported from Week 130 (data snapshot date: September 01, 2021) from the open-label extension trial enliGHten. Upon entry into enliGHten, all participants received lonapegsomatropin via vial/syringe, with subsequent switch to TransCon hGH Auto-Injector when available.

Results

A total of 298 participants (98% of parent trials) continued from the heiGHt or fliGHt trials into enliGHten. At Week 130, 36 participants had completed the trial and 248 participants remain enrolled. The height standard deviation score (SDS) mean (standard deviation [SD]) at Week 130 was -0.64 (0.85) compared with baseline value of -1.56 (0.88) at the start of enliGHten. Participants continued to approach the average parental height SDS mean (SD) of -0.39 (0.77). The annualized height velocity mean (SD) at Week 130 was 9.32 cm/year (0.45). Average IGF-1 SDS mean (SD) at Week 130 was 1.46 (1.18) compared with 0.52 (1.58) at enliGHten baseline. For the 36 participants who had completed the trial, 14 had reached bone age of >14 years (girls) or >16 years (boys), and 24 had completed the study based on investigator judgement that treatment for growth hormone deficiency was no longer necessary. The difference between mean (SD) height SDS at last visit and average parental height SDS was -0.05 (0.75) for the 36 completers, and 61.1% of these participants had met or exceeded the average parental height SDS. The mean (SD) total duration of hGH treatment for participants who completed the trial (including daily treatment and lonapegsomatropin) was 3.53 (0.88) years, and the mean (SD) duration of treatment with lonapegsomatropin was 2.20 (0.66). With continued lonapegsomatropin treatment, the AE profile remained consistent with what was observed in the parent trials, with no new safety signals.

Conclusions

Children and adolescents treated with lonapegsomatropin showed continued improvement of height SDS through their 3rd year of therapy. Lonapegsomatropin continued to demonstrate a safety profile comparable to that of daily somatropin therapy.

Presentation: Monday, June 13, 2022 12:30 p.m. - 12:35 p.m., Monday, June 13, 2022 12:30 p.m. - 2:30 p.m.

Switching to Weekly Lonapegsomatropin from Daily Somatropin in Children with Growth Hormone Deficiency: The fliGHt Trial

INTRODUCTION

The phase 3 fliGHt Trial evaluated the safety and tolerability of once-weekly lonapegsomatropin, a long-acting prodrug, in children with growth hormone deficiency (GHD) who switched from daily somatropin therapy to lonapegsomatropin.

METHODS

This multicenter, open-label, 26-week phase 3 trial took place at 28 sites across 4 countries (Australia, Canada, New Zealand, and the USA). The trial enrolled 146 children with GHD, 143 of which were previously treated with daily somatropin. All subjects received once-weekly lonapegsomatropin 0.24 mg human growth hormone/kg/week. The primary outcome measure was safety and tolerability of lonapegsomatropin over 26 weeks. Secondary outcome measures assessed annualized height velocity (AHV), height standard deviation score (SDS), and IGF-1 SDS at 26 weeks.

RESULTS

Subjects had a mean prior daily somatropin dose of 0.29 mg/kg/week. Treatment-emergent adverse events (AEs) reported were similar to the published AE profile of daily somatropin therapies. After switching to lonapegsomatropin, the least-squares mean (LSM) AHV was 8.7 cm/year (95% CI: 8.2, 9.2) at Week 26 and LSM height SDS changed from baseline to Week 26 of +0.25 (95% CI: 0.21, 0.29). Among switch subjects, the LSM for average IGF-1 SDS was sustained at Weeks 13 and 26, representing an approximate 0.7 increase from baseline (prior to switching from daily somatropin therapy). Patient-reported outcomes indicated a preference for weekly lonapegsomatropin among both children and their parents.

CONCLUSIONS

Lonapegsomatropin treatment outcomes were as expected across a range of ages and treatment experiences. Switching to lonapegsomatropin resulted in a similar AE profile to daily somatropin therapy.

Safety and Efficacy of Lonapegsomatropin in Children With Growth Hormone Deficiency: enliGHten Trial 2-Year Results

PURPOSE

The objectives of the ongoing, Phase 3, open-label extension trial enliGHten are to assess the long-term safety and efficacy of weekly administered long-acting growth hormone lonapegsomatropin in children with growth hormone deficiency.

METHODS

Eligible subjects completing a prior Phase 3 lonapegsomatropin parent trial (heiGHt or fliGHt) were invited to participate. All subjects were treated with lonapegsomatropin. Subjects in the United States switched to the TransCon hGH Auto-Injector when available. Endpoints were long-term safety, annualized height velocity, pharmacodynamics [insulin-like growth factor-1 SD score (SDS) values], and patient- and caregiver-reported assessments of convenience and tolerability.

RESULTS

Lonapegsomatropin treatment during enliGHten was associated with continued improvements in height SDS through week 104 in treatment-naïve subjects from the heiGHt trial (-2.89 to -1.37 for the lonapegsomatropin group; -3.0 to -1.52 for the daily somatropin group). Height SDS also continued to improve among switch subjects from the fliGHt trial (-1.42 at fliGHt baseline to -0.69 at week 78). After 104 weeks, the average bone age/chronological age ratio for each treatment group was 0.8 (0.1), showing only minimal advancement of bone age relative to chronological age with continued lonapegsomatropin treatment among heiGHt subjects. Fewer local tolerability reactions were reported with the TransCon hGH Auto-Injector compared with syringe/needle.

CONCLUSIONS

Treatment with lonapegsomatropin continued to be safe and well-tolerated, with no new safety signals identified. Children treated with once-weekly lonapegsomatropin showed continued improvement of height SDS through the second year of therapy without excess advancement of bone age.

SAT-LB16 Maintenance of Favorable Treatment Effect of Once-Weekly TransCon hGH for Children With Growth Hormone Deficiency: Interim Analysis From the Enlighten Long-Term Extension Trial

Background Once-weekly TransCon hGH is an investigational long-acting prodrug for growth hormone deficiency (GHD) that consists of 3 components: unmodified growth hormone (hGH; somatropin), an inert carrier that protects it, and a linker that temporarily binds the two. In the randomized phase 3 heiGHt Trial evaluating treatment-naïve children with GHD, TransCon hGH demonstrated superior annualized height velocity and ∆ height standard deviation score (SDS) compared to Genotropin and had a similar safety and tolerability profile. Methods Results are reported from an interim analysis of subjects from heiGHt who continued in the ongoing enliGHten long-term extension trial for 26 weeks. In the 52-week heiGHt Trial, treatment-naïve, prepubertal subjects with GHD were randomized 2:1 to receive once-weekly TransCon hGH 0.24 mg hGH/kg/week or an equivalent weekly dose of daily Genotropin. Subjects completing heiGHt could enroll in enliGHten, where all subjects received TransCon hGH. Two groups were analyzed: Group A (TransCon hGH in both heiGHt and enliGHten) and Group B (Genotropin in heiGHt, followed by TransCon hGH in enliGHten). Safety and growth outcomes were evaluated approximately every 13 weeks in heiGHt and enliGHten. IGF-1 was sampled on postdose Day 5 (±1 day) in enliGHten. A by-visit ANCOVA model was used to analyze numeric efficacy endpoints.ResultsAll but one subject who completed heiGHt continued into enliGHten (A: N=103, B: N=55). Baseline characteristics at the start of heiGHt were balanced between groups. The statistically significant treatment difference in ∆ height SDS (Group A vs B) at the end of heiGHt (Week 52, N=159; 1.10 vs 0.96, P=0.0149) was sustained through Week 78 (N=154; 1.39 vs 1.24, P=0.0436), demonstrating persistence of catch-up growth for both groups and maintenance of superior treatment effect for subjects treated with TransCon hGH in the first year of therapy. At Week 78, least-squares mean (SE) IGF-1 SDS on postdose Day 5 (N=153) was 0.52 (0.15) for Group A and 0.59 (0.19) for Group B. Adverse events (AEs) were comparable between groups during heiGHt. During enliGHten, 48.7% (76/156) and 1.9% (3/156) of subjects experienced AEs and serious AEs, respectively; the AE profile was consistent with what was previously observed in heiGHt. A low titer of anti-hGH binding antibodies were detected in 10/156 (6.4%) subjects during treatment with TransCon hGH in heiGHt and enliGHten; no neutralizing antibodies were detected. Lab parameters (HbA1c, cortisol, free thyroxine) were stable and generally remained within the normal range throughout the trials. Mean (SD) BMI SDS was 0.0 (0.8) for Group A and 0.1 (0.9) for Group B at Week 78.Conclusions Children treated with TransCon hGH showed continued improvement of height SDS beyond the first year. Treatment with TransCon hGH through 78 weeks demonstrated an AE and immunogenicity profile comparable to that of a daily hGH therapy.

A Simulated Application of the Hartford Hospital Aminoglycoside Dosing Nomogram for Plazomicin Dosing Interval Selection in Patients With Serious Infections Caused by Carbapenem-Resistant Enterobacterales

PURPOSE

In the Phase III Study of Plazomicin Compared With Colistin in Patients With Infection Due to Carbapenem-Resistant Enterobacteriaceae (CARE), plazomicin was studied for the treatment of critically ill patients with infections caused by carbapenem-resistant Enterobacterales. Initial plazomicin dosing was guided by creatinine clearance (CrCl) and subsequent doses adjusted by therapeutic drug monitoring to achieve AUC_0-24 exposures within a target range (210-315 mg∙h/L). We applied the Hartford nomogram to evaluate whether this clinical tool could reduce plazomicin troughs levels and increase the proportion of patients within the target AUC range.

METHODS

Thirty-seven patients enrolled in cohorts 1 or 2 of CARE were eligible for analyses. Observed 10-hour concentrations after the initial dose were plotted on the Hartford nomogram to determine an eligible dosing interval group (q24h, q36h or q48h). On the basis of baseline CrCl, a 15- or 10-mg/kg dose was simulated with the nomogram-recommended dosing interval. The proportion of patients in each dosing interval group with a trough ≥3 mg/L (trough threshold associated with serum creatinine increases ≥0.5 mg/dL in product label) was quantified. Simulated interval-normalized AUC_0-24 was compared with the target AUC range.

FINDINGS

Among the 28 patients with a CrCl ≥60 mL/min, the nomogram recommended every-24-hour dosing in 61% and an extended-interval (q36h or q48h) in 39% of patients. For patients with a CrCl ≥30-59 mL/min (n = 9), the nomogram recommended every-24-hour dosing and an extended-interval in 22% and 78% of patients, respectively. Among both renal function cohorts, exposure simulation with the nomogram significantly reduced the proportion of patients with trough concentrations ≥3 mg/L (CrCl ≥60 mL/min cohort: 91% vs 9%, P < 0.001; CrCl ≥30-59 mL/min cohort, 100% vs 0%, P < 0.001). Relative to the observed mean (SD) AUC_0-24 of 309 mg∙h/mL (96 mg∙h/mL), simulation of extended intervals resulted in a mean interval-normalized AUC_0-24 of 210 mg∙h/mL (40 mg∙h/mL) in all patients eligible for an extended interval, resulting in a similar proportion (49% vs 54%) of patients within the target AUC_0-24 range after the first dose.

IMPLICATIONS

Application of the Hartford nomogram successfully reduced the likelihood of elevated plazomicin trough concentrations while improving AUC exposures in these patients with carbapenem-resistant Enterobacterales infections.

Once-Daily Plazomicin for Complicated Urinary Tract Infections

BACKGROUND

The increasing multidrug resistance among gram-negative uropathogens necessitates new treatments for serious infections. Plazomicin is an aminoglycoside with bactericidal activity against multidrug-resistant (including carbapenem-resistant) Enterobacteriaceae.

METHODS

We randomly assigned 609 patients with complicated urinary tract infections (UTIs), including acute pyelonephritis, in a 1:1 ratio to receive intravenous plazomicin (15 mg per kilogram of body weight once daily) or meropenem (1 g every 8 hours), with optional oral step-down therapy after at least 4 days of intravenous therapy, for a total of 7 to 10 days of therapy. The primary objective was to show the noninferiority of plazomicin to meropenem in the treatment of complicated UTIs, including acute pyelonephritis, with a noninferiority margin of 15 percentage points. The primary end points were composite cure (clinical cure and microbiologic eradication) at day 5 and at the test-of-cure visit (15 to 19 days after initiation of therapy) in the microbiologic modified intention-to-treat population.

RESULTS

Plazomicin was noninferior to meropenem with respect to the primary efficacy end points. At day 5, composite cure was observed in 88.0% of the patients (168 of 191 patients) in the plazomicin group and in 91.4% (180 of 197 patients) in the meropenem group (difference, -3.4 percentage points; 95% confidence interval [CI], -10.0 to 3.1). At the test-of-cure visit, composite cure was observed in 81.7% (156 of 191 patients) and 70.1% (138 of 197 patients), respectively (difference, 11.6 percentage points; 95% CI, 2.7 to 20.3). At the test-of-cure visit, a higher percentage of patients in the plazomicin group than in the meropenem group were found to have microbiologic eradication, including eradication of Enterobacteriaceae that were not susceptible to aminoglycosides (78.8% vs. 68.6%) and Enterobacteriaceae that produce extended-spectrum β-lactamases (82.4% vs. 75.0%). At late follow-up (24 to 32 days after initiation of therapy), fewer patients in the plazomicin group than in the meropenem group had microbiologic recurrence (3.7% vs. 8.1%) or clinical relapse (1.6% vs. 7.1%). Increases in serum creatinine levels of 0.5 mg or more per deciliter (≥40 μmol per liter) above baseline occurred in 7.0% of patients in the plazomicin group and in 4.0% in the meropenem group.

CONCLUSIONS

Once-daily plazomicin was noninferior to meropenem for the treatment of complicated UTIs and acute pyelonephritis caused by Enterobacteriaceae, including multidrug-resistant strains. (Funded by Achaogen and the Biomedical Advanced Research and Development Authority; EPIC ClinicalTrials.gov number, NCT02486627.).

No Effect of Plazomicin on the Pharmacokinetics of Metformin in Healthy Subjects

Plazomicin is an aminoglycoside that was engineered to overcome aminoglycoside-modifying enzymes, which are the most common aminoglycoside resistance mechanism in Enterobacteriaceae. Because plazomicin is predominantly eliminated via renal pathways, an in vitro study was conducted to determine whether plazomicin inhibits the organic cation transporter 2 (OCT2) and the multidrug and toxin extrusion (MATE1 and MATE2-K) transporters, using metformin as a probe substrate. Plazomicin inhibited OCT2, MATE1, and MATE2-K transporters with half-maximal inhibition of the transporter values of 5120, 1300, and 338 µg/mL, respectively. To determine whether this in vitro inhibition translates in vivo, an open-label, randomized, 2-period, 2-treatment crossover study (NCT03270553) was carried out in healthy subjects (N = 16), who received a single oral dose of metformin 850 mg alone and in combination with a single intravenous infusion of plazomicin 15 mg/kg. Geometric least-squares mean ratios of the test treatment (combination) vs the reference treatment (metformin alone) and 90% confidence intervals were within the equivalence interval of 80% to 125% (peak plasma concentration, 104.5 [95.1-114.9]; area under the plasma concentration-time curve from time zero to time of last quantifiable concentration, 103.7 [93.5-115.0]; area under the plasma concentration-time curve from time zero to infinity, 104.0 [94.2-114.8]). The results demonstrate that there is no clinically significant drug-drug interaction resulting from coadministration of single doses of intravenous plazomicin 15 mg/kg and oral metformin 850 mg in healthy subjects. Coadministration of plazomicin and metformin was well tolerated in healthy subjects.

A Phase 1 Study To Assess the Pharmacokinetics of Intravenous Plazomicin in Adult Subjects with Varying Degrees of Renal Function

Plazomicin is an FDA-approved aminoglycoside for the treatment of complicated urinary tract infections. In this open-label study, 24 adults with normal renal function or mild, moderate, or severe renal impairment (n = 6 per group) received a single 7.5-mg/kg of body weight dose of plazomicin as a 30-min intravenous infusion. Total clearance declined with renal impairment, resulting in 1.98-fold and 4.42-fold higher plazomicin exposures, as measured by the area under the concentration-time curve from 0 h to infinity, in subjects with moderate and severe impairment, respectively, than in subjects with normal renal function. (This study has been registered at ClinicalTrials.gov under identifier NCT01462136.).