Impact of dose-escalation schemes and drug discontinuation on weight loss outcomes with liraglutide 3.0 mg: A model-based approach

Pharmacological management of testosterone deficiency in men current advances and future directions

INTRODUCTION

Testosterone deficiency (TD) is relatively common in aging men, affecting around 2% of the general population. Testosterone replacement therapy (TRT) represents the most common medical approach for subjects who are not interested in fathering.

AREAS COVERED

This review summarizes advances in TRT, including approved or non-approved pharmacological options to overcome TD. When possible, a meta-analytic approach was applied to minimize subjective and biased interpretations of the available data.

EXPERT OPINION

During the last decade, several new TRT formulations have been introduced on the market, including oral, transdermal, and parenteral formulations. Possible advantages and limitations have been discussed appropriately. Anti-estrogens, including selective estrogen modulators or aromatase inhibitors still represent further possible off-label options. However, long-term side effects on sexual function and bone parameters constitute major limitations. Glucagon-like peptide 1 analogues can be an alternative option in particular for massive obesity-associated TD. Weight loss obtained through lifestyle modifications including diet and physical exercise should be encouraged in all overweight and obese patients. A combination of TRT and lifestyle changes can be considered in those subjects in whom a reversal of the condition cannot be expected in a reasonable time frame.

Liraglutide's Effect on Weight Management in Subjects With Pre-diabetes: A Systematic Review & Meta-Analysis

BACKGROUND

Despite the growing literature, the effectiveness of liraglutide in weight management among individuals with prediabetes and in preventing the disease remains controversial. This study aims to critically evaluate the extent of liraglutide's impact on weight management in this population and assess the heterogeneity among extant studies.

METHODS

A systematic literature search was conducted across MEDLINE, Embase, ClinicalTrials.gov, and the reference list of retrieved studies to identify eligible English language randomized controlled trials evaluating liraglutide's effect on weight in individuals with pre-diabetes. Non-randomized studies, studies not reporting relevant outcomes, and those conducted on patients with type 2 diabetes were excluded from this review. Outcomes included a change from baseline in absolute body weight in kg, body mass index (BMI), waist circumference, glycosylated hemoglobin (HbA1c), and low-density lipoprotein cholesterol levels. Additional safety outcomes were also reported. Data were analyzed using R statistical software version 4.3.1. A fixed-effect model was used when pooling crude numbers for study outcomes. Moreover, a sensitivity analysis using random-effect model was performed and heterogeneity was assessed using I2 statistics.

RESULTS

Five eligible studies were included, with a total of 1604 subjects in the liraglutide arm and 859 subjects in the control arm. Participants exposed to liraglutide showed a decrease in body weight (mean difference [MD] = -4.95 kg; 95% CI -5.16, -4.73; I2 = 93%), BMI (MD = -2.06 kg/m2; 95%CI -2.22, -1.89; I2 = 97%), waist circumference (MD = -4.61 cm; 95% CI -4.79, -4.43; I2 = 82%), HbA1c (MD = -0.33%; 95%CI -0.34, -0.31; I2 = 100%), and low-density lipoprotein cholesterol levels (MD = -0.36 mmol/L; 95% CI -0.39, -0.33; I2 = 99%). The overall effect size remained similar when using a random-effects model for all outcomes. In addition, the rate of adverse events was higher with liraglutide when compared to the control; however, the dropout rates were relatively lower in the former arm.

CONCLUSION

While our meta-analysis suggests that liraglutide can reduce body weight, BMI, waist circumference, and HbA1c levels in individuals with pre-diabetes, the findings should be interpreted cautiously due to limitations such as the small number of trials and their short duration, and variability in dosages. Further randomized controlled trials examining long-term outcomes are essential to validate these findings and address the high heterogeneity among the studies included in this analysis.

A model-based approach to predict individual weight loss with semaglutide in people with overweight or obesity

AIMS

To determine the relationship between exposure and weight-loss trajectories for the glucagon-like peptide-1 analogue semaglutide for weight management.

MATERIALS AND METHODS

Data from one 52-week, phase 2, dose-ranging trial (once-daily subcutaneous semaglutide 0.05-0.4 mg) and two 68-week phase 3 trials (once-weekly subcutaneous semaglutide 2.4 mg) for weight management in people with overweight or obesity with or without type 2 diabetes were used to develop a population pharmacokinetic (PK) model describing semaglutide exposure. An exposure-response model describing weight change was then developed using baseline demographics, glycated haemoglobin and PK data during treatment. The ability of the exposure-response model to predict 1-year weight loss based on weight data collected at baseline and after up to 28 weeks of treatment, was assessed using three independent phase 3 trials.

RESULTS

Based on population PK, exposure levels over time consistently explained the weight-loss trajectories across trials and dosing regimens. The exposure-response model had high precision and limited bias for predicting body weight loss at 1 year in independent datasets, with increased precision when data from later time points were included in the prediction.

CONCLUSION

An exposure-response model has been established that quantitatively describes the relationship between systemic semaglutide exposure and weight loss and predicts weight-loss trajectories for people with overweight or obesity who are receiving semaglutide doses up to 2.4 mg once weekly.

Potential contributors to variation in weight-loss response to liraglutide

Obesity treatment requires a chronic state of negative energy balance. Obesity medications can help with this, increasing long-term dietary compliance by promoting satiety or reducing hunger. However, efficacy and safety of obesity medications vary for individuals. Early identification of non-responders to obesity medications may limit drug exposure while optimizing benefits for responders. This review summarizes factors that impact weight-loss response to liraglutide. Factors linked to greater weight loss on liraglutide include being female, not having diabetes, having relatively high baseline weight, and losing at least 4% of initial weight after 16 weeks of treatment. Other covariates that may predict treatment response but require further confirmation include central effects, nausea, gastric emptying of solids, and genotype. Baseline body mass index, race, and age seem less relevant for predicting weight-loss response to liraglutide. Lesser known and harder-to-measure factors such as cerebral blood flow, food cue reactivity, gut hormone levels, and dietary adherence possibly impact variability of response to liraglutide. This information should assist healthcare providers with establishing realistic weight-loss probability for individual patients. Future research should improve the ability to identify responders to liraglutide. Importantly, this review may provide a framework to identify responders to other obesity medications.

Current treatment landscape for obesity in Singapore

The rising prevalence of obesity in Singapore is a harbinger for a corresponding increase in obesity-related complications such as type 2 diabetes mellitus (T2DM) and coronary heart disease. Obesity is a complex disease driven by multiple factors, and hence, treatment cannot follow a 'one-size-fits-all' approach. Lifestyle modifications involving dietary interventions, physical activity and behavioural changes remain the cornerstone of obesity management. However, similar to other chronic diseases such as T2DM and hypertension, lifestyle modifications are often insufficient on their own, hence the importance of other treatment modalities including pharmacotherapy, endoscopic bariatric therapy and metabolic-bariatric surgery. Weight loss medications currently approved in Singapore include phentermine, orlistat, liraglutide and naltrexone-bupropion. In recent years, endoscopic bariatric therapies have evolved as an effective, minimally invasive and durable therapeutic option for obesity. Metabolic-bariatric surgery remains the most effective and durable treatment for patients with severe obesity, with an average weight loss of 25%-30% after one year.

Gastrointestinal tolerability of once-weekly semaglutide 2.4 mg in adults with overweight or obesity, and the relationship between gastrointestinal adverse events and weight loss

AIM

We evaluated gastrointestinal (GI) adverse events (AEs) with once-weekly semaglutide 2.4 mg in adults with overweight or obesity and their contribution to weight loss (WL).

MATERIALS AND METHODS

AE analyses pooled data from the Semaglutide Treatment Effect in People With Obesity (STEP) 1-3 trials for participants randomized to 68 weeks of semaglutide 2.4 mg (n = 2117) or placebo (n = 1262). WL was analysed by presence/absence of GI AEs. Mediation analysis estimated WL effects mediated by and unrelated to GI AEs. GI tolerability with semaglutide 2.4 mg maintenance and cessation after dose escalation was evaluated using STEP 4 data among 803 participants tolerating 20 weeks of semaglutide run-in.

RESULTS

GI AEs were more common with semaglutide 2.4 mg than placebo, with most frequently nausea (43.9% vs. 16.1% of participants), diarrhoea (29.7% vs. 15.9%), vomiting (24.5% vs. 6.3%) and constipation (24.2% vs. 11.1%). Most GI AEs with semaglutide were non-serious (99.5% of AEs), mild-to-moderate (98.1%), transient and occurred most frequently during/shortly after dose escalation. Few semaglutide-treated participants (4.3%) permanently discontinued treatment for GI AEs. In STEP 1-3, mean WL with semaglutide 2.4 mg was similar in participants without (9.6%-17.1%) versus with GI AEs (11.4%-17.7%). Consistent with this observation, mediation analysis found that GI AEs contributed little to semaglutide-induced WL: of the additional 7.6%-14.4% WL with semaglutide versus placebo, <1 percentage point was mediated by GI AEs. In STEP 4, semaglutide 2.4 mg maintenance was well tolerated.

CONCLUSIONS

GI AEs were more common with semaglutide 2.4 mg than placebo, but typically mild-to-moderate and transient. Semaglutide-induced WL was largely independent of GI AEs.

Impact of dose-escalation schemes and drug discontinuation on weight loss outcomes with liraglutide 3.0 mg: A model-based approach

AIMS

To investigate the impact on weight loss of the treatment changes in overweight or obese people that may be needed in case of gastrointestinal (GI) tolerability issues during escalation of the glucagon-like peptide-1 analogue liraglutide.

MATERIALS AND METHODS

The individual longitudinal body weight data from the main trial periods of three phase II/III trials in overweight or obese patients (56-week treatment with once-daily liraglutide 1.2, 1.8, 2.4 or 3.0 mg or placebo, n = 4952) were analysed using a non-linear mixed-effect modelling approach. Individual pharmacokinetic profiles were derived based on published pharmacokinetic models. Baseline body weight, baseline glycated haemoglobin (HbA1c), age, gender, diabetes status (no diabetes, prediabetes or type 2 diabetes), race and trial region were investigated as covariates. As a form of external validation, the model was used to predict the weight regain after treatment cessation at week 56 (data not included in model development).

RESULTS

A pharmacokinetic/pharmacodynamic model provided an adequate description of the weight loss trajectories for all studied doses. Gender and diabetes status were identified as the most influential covariates, and an underlying seasonal weight fluctuation was identified. Slower than that recommended, one-week dose-escalation algorithms led up to 2 weeks slower initial weight loss but similar long-term weight loss trajectories.

CONCLUSIONS

The relationship between liraglutide systemic exposure and weight loss was successfully established in overweight or obese people. The model could predict the time course of weight regain after treatment cessation and suggests that GI tolerability can be mitigated by slower escalation with only minor impact on the weight loss trajectory.