Body Composition Changes with Long-term Pegvisomant Therapy of Acromegaly

Temporal and masseter muscle evaluation by MRI provides information on muscle mass and quality in acromegaly patients

PURPOSE

The impact of GH/IGF-1 levels on skeletal muscle in acromegaly is still controversial. Temporal (TMT) and masseter muscle (MMT) thickness has been recently demonstrated as a reliable measure of muscle mass. We aimed to investigate the relationship between TMT, MMT and clinical/biochemical characteristics in patients with acromegaly.

METHODS

Single center retrospective longitudinal study including 69 patients with at least one available brain/sella turcica MRI and matched clinical data. TMT, MMT, and muscle fatty infiltration (modified Goutallier score) were evaluated in all patients at baseline (first available MRI) and over time (182 MRIs analyzed).

RESULTS

At baseline, both TMT and MMT were higher in males than females (p = 0.001 and p = 0.016, respectively). TMT and MMT were positively associated (β 0.508, p < 0.001), and they were positively correlated with IGF-1 xULN (TMT, p = 0.047; MMT, p = 0.001). MMT had a positive correlation with patients' weight (p = 0.015) and height (p = 0.006). No correlation was found between TMT, MMT and the presence of hypogonadism. Considering all available MRIs, sex and IGF-1 xULN were significant determinants of TMT and MMT at multivariable analysis (female sex: β -0.345/-0.426, p < 0.001; IGF-1 xULN: β 0.257/0.328, p < 0.001). At longitudinal evaluation, uncontrolled patients at baseline showed a significant reduction of MMT over time (p = 0.044). Remarkable fatty infiltration was observed in 34-37% of MRIs; age was the main determinant (temporal muscle: OR 1.665; p = 0.013; masseter muscle: OR 1.793; p = 0.009).

CONCLUSION

Male patients with higher IGF-1 values have thicker temporal and masseter muscles, suggesting that sex and IGF-1 have a significant impact on muscle mass in acromegaly.

Long-term Pegvisomant Therapy of Acromegaly: Effects on Bone Density, Turnover and Microstructure Using HRpQCT

Context

Fracture rate is increased in patients with active acromegaly and those in remission. Abnormalities of bone microstructure are present in patients with active disease and persist despite biochemical control after surgery. Effects of treatment with the GH receptor antagonist pegvisomant on bone microstructure were unknown.

Methods

We studied 25 patients with acromegaly (15 men, 10 women). In 20, we evaluated areal bone mineral density (BMD) by dual-energy X-ray absorptiometry and bone turnover markers (BTMs) longitudinally, before and during pegvisomant treatment. After long-term pegvisomant in 17, we cross-sectionally assessed volumetric BMD, microarchitecture, stiffness, and failure load of the distal radius and tibia using high-resolution peripheral quantitative computed tomography (HRpQCT) and compared these results to those of healthy controls and 2 comparison groups of nonpegvisomant-treated acromegaly patients, remission, and active disease, matched for other therapies and characteristics.

Results

In the longitudinal study, areal BMD improved at the lumbar spine but decreased at the hip in men after a median ∼7 years of pegvisomant. In the cross-sectional study, patients on a median ∼9 years of pegvisomant had significantly larger bones, lower trabecular and cortical volumetric density, and disrupted trabecular microarchitecture compared to healthy controls. Microstructure was similar in the pegvisomant and acromegaly comparison groups. BTMs were lowered, then stable over time.

Conclusion

In this, the first study to examine bone microstructure in pegvisomant-treated acromegaly, we found deficits in volumetric BMD and microarchitecture of the peripheral skeleton. BTM levels remained stable with long-term therapy. Deficits in bone quality identified by HRpQCT may play a role in the pathogenesis of fragility in treated acromegaly.

Skeletal Muscle Evaluation in Patients With Acromegaly

Context

Patients with acromegaly are characterized by chronic exposure to high growth hormone (GH) and insulin-like growth factor-1 levels, known for their anabolic effect on skeletal muscle. Therefore, an increased skeletal muscle mass could be hypothesized in these individuals. Herein, we have performed a systematic revision of published evidence regarding skeletal muscle mass, quality, and performance in patients with acromegaly.

Evidence Acquisition

A systematic review of the literature in the PubMed database up to September 1, 2023, was conducted with the following query: acromegaly AND ("muscle mass" OR "skeletal muscle"). We excluded studies that did not compare different disease states or used nonradiological methods for the skeletal muscle analyses, except for bioelectrical impedance analysis.

Evidence Synthesis

Fifteen studies met the inclusion criteria. A total of 360 patients were evaluated for skeletal muscle mass, 122 for muscle fatty atrophy, and 192 for muscle performance. No clear evidence of increased skeletal muscle mass in patients with active disease compared to control or healthy individuals emerged. As for skeletal muscle quality, we observed a trend toward higher fatty infiltration among patients with acromegaly compared to healthy participants. Likewise, patients with active disease showed consistently worse physical performance compared to control or healthy individuals.

Conclusion

Skeletal muscle in acromegaly has lower quality and performance compared to that of healthy individuals. The small number of published studies and multiple confounding factors (eg, use of different radiological techniques) contributed to mixed results, especially regarding skeletal muscle mass. Well-designed prospective studies are needed to investigate skeletal muscle mass in patients with acromegaly.

Growth hormone and nonalcoholic fatty liver disease

Nonalcoholic fatty liver disease (NAFLD) is a prevalent cause of liver disease and metabolic comorbidities. Obesity is strongly associated with NAFLD and is also a state of relative deficiency of growth hormone (GH). Evidence supports a role of reduced GH and insulin-like growth factor-1 (IGF-1) in NAFLD pathogenesis. Physiological actions of GH in the liver include suppression of de novo lipogenesis (DNL) and promotion of lipid beta-oxidation, and GH also appears to have anti-inflammatory actions. Physiologic actions of IGF-1 include suppression of inflammatory and fibrogenic pathways important in the evolution from steatosis to steatohepatitis and fibrosis. Rodent models of impaired hepatic GH signaling show the development of steatosis, sometimes accompanied by inflammation, hepatocellular damage, and fibrosis, and these changes are ameliorated by treatment with GH and/or IGF-1. In humans, individuals with GH deficiency and GH resistance demonstrate an increased prevalence of NAFLD compared to controls, with improvement in hepatic lipid, steatohepatitis, and fibrosis following GH replacement. As a corollary, individuals with GH excess demonstrate lower hepatic lipid compared to controls along with increased hepatic lipid following treatment to normalize GH levels. Clinical trials demonstrate that augmentation of GH reduces hepatic lipid content in individuals with NAFLD and may also ameliorate steatohepatitis and fibrosis. Taken together, evidence supports an important role for perturbations in the GH/IGF-1 axis as one of the pathogenic mechanisms of NAFLD and suggests that further study is needed to assess whether augmentation of GH and/or IGF-1 may be a safe and effective therapeutic strategy for NAFLD.

Metabolomics in acromegaly: a systematic review

The therapeutic response heterogeneity in acromegaly persists, despite the medical-surgical advances of recent years. Thus, personalized medicine implementation, which focuses on each patient, is justified. Metabolomics would decipher the molecular mechanisms underlying the therapeutic response heterogeneity. Identification of altered metabolic pathways would open new horizons in the therapeutic management of acromegaly. This research aimed to evaluate the metabolomic profile in acromegaly and metabolomics' contributions to understanding disease pathogenesis. A systematic review was carried out by querying four electronic databases and evaluating patients with acromegaly through metabolomic techniques. In all, 21 studies containing 362 patients were eligible. Choline, the ubiquitous metabolite identified in growth hormone (GH)-secreting pituitary adenomas (Pas) by in vivo magnetic resonance spectroscopy (MRS), negatively correlated with somatostatin receptors type 2 expression and positively correlated with magnetic resonance imaging T2 signal and Ki-67 index. Moreover, elevated choline and choline/creatine ratio differentiated between sparsely and densely granulated GH-secreting PAs. MRS detected low hepatic lipid content in active acromegaly, which increased after disease control. The panel of metabolites of acromegaly deciphered by mass spectrometry (MS)-based techniques mainly included amino acids (especially branched-chain amino acids and taurine), glyceric acid, and lipids. The most altered pathways in acromegaly were the metabolism of glucose (particularly the downregulation of the pentose phosphate pathway), linoleic acid, sphingolipids, glycerophospholipids, arginine/proline, and taurine/hypotaurine. Matrix-assisted laser desorption/ionization coupled with MS imaging confirmed the functional nature of GH-secreting PAs and accurately discriminated PAs from healthy pituitary tissue.

Control of acromegaly in more than 90% of patients after 10 years of pegvisomant therapy: an European referral centre real-life experience

PURPOSE

Pegvisomant (PEG) efficaciously controls IGF-I excess in acromegaly and possesses a positive impact on glucose metabolism. Data on very prolonged PEG treatment are still limited, therefore, we investigated the effects of 10-years PEG on disease control, maximal tumour diameter (MTD), and metabolic profile in consecutive patients resistant to somatostatin analogues (SRLs) followed in an European referral centre for acromegaly.

METHODS

Since the 2000s, we collected data on anthropometric, hormonal and metabolic parameters, and MTD of patients receiving PEG. In the current study, we included 45 patients (19 men, 26 women, 46.8 ± 11 years) treated for at least 5 years with PEG mono or combined therapy, analyzing data before, after 5- and 10-years PEG.

RESULTS

After10 years, 91% of patients showed full disease control and in 37% a significant decrease in MTD was found. Diabetes prevalence was slightly increased, whereas HbA1c remained stable over the decade. Transaminases remained stable and no case of cutaneous lipohypertrophy was recorded. A different metabolic impact between mono- or combined therapy was found. Patients in monotherapy showed significantly lower fasting glucose (p = 0.01), fasting insulin (p = 0.008), HbA1c (p = 0.007), HOMA-IR (p = 0.001), and significantly higher ISI₀ (p = 0.002), whereas patients under combined therapy showed significantly lower total (p = 0.03), and LDL cholesterol (p = 0.007). Acromegaly duration before PEG was inversely related to ΔFG (r = - 0.46, p = 0.03) and ΔFI (r = - 0.54, p = 0.05).

CONCLUSIONS

PEG is effective and safe in long term. In patients resistant to SRLs, early beginning of PEG allows a wider gluco-insulinemic improvement.

Long-term Outcome of Body Composition, Ectopic Lipid, and Insulin Resistance Changes With Surgical Treatment of Acromegaly

Context

Acromegaly presents a unique pattern of lower adiposity and insulin resistance in active disease but reduction in insulin resistance despite a rise in adiposity after surgery. Depot-specific adipose tissue masses and ectopic lipid are important predictors of insulin resistance in other populations, but whether they are in acromegaly is unknown. Long-term persistence of body composition changes after surgery is unknown.

Objective

To determine how depot-specific body composition and ectopic lipid relate to insulin resistance in active acromegaly and whether their changes with surgery are sustained long-term.

Methods

Cross-sectional study in patients with active acromegaly and longitudinal study in newly diagnosed patients studied before and in long-term follow-up, 3 (1-8) years (median, range), after surgery. Seventy-one patients with active acromegaly studied cross-sectionally and 28 with newly diagnosed acromegaly studied longitudinally. Main outcome measures were visceral (VAT), subcutaneous (SAT), and intermuscular adipose tissue masses by whole-body magnetic resonance imaging; intrahepatic lipid (IHL) by proton magnetic resonance spectroscopy; insulin resistance measures derived from fasting; and oral glucose tolerance test insulin and glucose levels.

Results

SAT and insulin-like growth factor 1 level, but not VAT or IHL, were independent predictors of insulin resistance in active acromegaly. VAT, SAT, and IHL gains were sustained long-term after surgery. VAT mass rise with surgery correlated inversely with rise in QUICKI while SAT rise correlated with fall in the Homeostatic Model Assessment score.

Conclusion

SAT and disease activity are important predictors of insulin resistance in active acromegaly. Adiposity gains are sustained long-term after surgical treatment and impact on the accompanying improvement in insulin resistance.

Ectopic lipid deposition and insulin resistance in patients with GH disorders before and after treatment

OBJECTIVES

Insulin resistance is associated with ectopic lipid deposition. Growth hormone (GH) status also modulates ectopic lipid accumulation, but how this associates with insulin resistance in patients with GH disorders is not well established.

DESIGN AND METHODS

Twenty-one patients diagnosed with acromegaly and 12 patients with adult GH deficiency (GHD) were studied at diagnosis and after treatment. A reference group of 12 subjects was included. Each study day comprised assessment of body composition with dual-energy X-ray absorptiometry, ectopic lipid deposition in the liver by MR spectroscopy, and Homeostatic Model Assessment for Insulin Resistance (HOMA-IR).

RESULTS

Disease control of acromegaly decreased lean body mass (LBM) (P < .000) and increased the percentage of total body fat (TBF) (P < .000). GH replacement increased LBM in the GHD patients (P = .007) and decreased the percentage of TBF (P = .010). The intrahepatic lipid (IHL) content increased after disease control in acromegaly (P = .004), whereas IHL did not change significantly after GH replacement in GHD (P = .34). Insulin resistance (HOMA-IR) improved after disease control of acromegaly (P < .000) and remained unaltered after GH replacement in the GHD patients (P = .829).

CONCLUSIONS

GH status is a significant modulator of body composition and insulin sensitivity.GH excess reduces total fat mass and intrahepatic lipid content together with induction of insulin resistance.The data support the notion that GH-induced insulin resistance is unassociated with hepatic lipid accumulation.

Acromegaly: pathogenesis, diagnosis, and management

Growth hormone-secreting pituitary adenomas that cause acromegaly arise as monoclonal expansions of differentiated somatotroph cells and are usually sporadic. They are almost invariably benign, yet they can be locally invasive and show progressive growth despite treatment. Persistent excess of both growth hormone and its target hormone insulin-like growth factor 1 (IGF-1) results in a wide array of cardiovascular, respiratory, metabolic, musculoskeletal, neurological, and neoplastic comorbidities that might not be reversible with disease control. Normalisation of IGF-1 and growth hormone are the primary therapeutic aims; additional treatment goals include tumour shrinkage, relieving symptoms, managing complications, reducing excess morbidity, and improving quality of life. A multimodal approach with surgery, medical therapy, and (more rarely) radiation therapy is required to achieve these goals. In this Review, we examine the epidemiology, pathogenesis, diagnosis, complications, and treatment of acromegaly, with an emphasis on the importance of tailoring management strategies to each patient to optimise outcomes.

The acromegaly lipodystrophy

Growth hormone (GH) and insulin-like growth factor 1 (IGF-1) are essential to normal growth, metabolism, and body composition, but in acromegaly, excesses of these hormones strikingly alter them. In recent years, the use of modern methodologies to assess body composition in patients with acromegaly has revealed novel aspects of the acromegaly phenotype. In particular, acromegaly presents a unique pattern of body composition changes in the setting of insulin resistance that we propose herein to be considered an acromegaly-specific lipodystrophy. The lipodystrophy, initiated by a distinctive GH-driven adipose tissue dysregulation, features insulin resistance in the setting of reduced visceral adipose tissue (VAT) mass and intra-hepatic lipid (IHL) but with lipid redistribution, resulting in ectopic lipid deposition in muscle. With recovery of the lipodystrophy, adipose tissue mass, especially that of VAT and IHL, rises, but insulin resistance is lessened. Abnormalities of adipose tissue adipokines may play a role in the disordered adipose tissue metabolism and insulin resistance of the lipodystrophy. The orexigenic hormone ghrelin and peptide Agouti-related peptide may also be affected by active acromegaly as well as variably by acromegaly therapies, which may contribute to the lipodystrophy. Understanding the pathophysiology of the lipodystrophy and how acromegaly therapies differentially reverse its features may be important to optimizing the long-term outcome for patients with this disease. This perspective describes evidence in support of this acromegaly lipodystrophy model and its relevance to acromegaly pathophysiology and the treatment of patients with acromegaly.

Growth Hormone and Insulin-Like Growth Factor 1 Regulation of Nonalcoholic Fatty Liver Disease

Patients with obesity have a high prevalence of nonalcoholic fatty liver disease (NAFLD), representing a spectrum of simple steatosis to nonalcoholic steatohepatitis (NASH), without and with fibrosis. Understanding the etiology of NAFLD is clinically relevant since NAFLD is an independent risk factor for diabetes and cardiovascular disease. In addition, NASH predisposes patients to the development of cirrhosis and hepatocellular carcinoma, and NASH cirrhosis represents the fastest growing indication for liver transplantation in the United States. It is appreciated that multiple factors are involved in the development and progression of NAFLD. Growth hormone (GH) and insulin-like growth factor 1 (IGF1) regulate metabolic, immune, and hepatic stellate cell function, and alterations in the production and function of GH is associated with obesity and NAFLD/NASH. Therefore, this review will focus on the potential role of GH and IGF1 in the regulation of hepatic steatosis, inflammation, and fibrosis.

Personalized Medical Treatment in Patients with Acromegaly: A Review

Acromegaly is associated with significant morbidity and mortality if not appropriately treated. In addition to insulin-like growth factor 1 (IGF-1) and growth hormone (GH) normalization, and tumor shrinkage, treatment goals include symptom relief, managing complications and improving quality of life. Surgical resection is a first-line treatment in most patients, with few being pretreated pre-operatively with medications. Somatostatin receptor ligands (SRLs), injectable and more recently oral capsules, have been the cornerstone of first-line medical therapy for persistent disease. However, several factors, including sparsely granulated adenomas, absent/low somatostatin receptor (SSTR2) status, imaging T2-hyperintensity, young age and aryl hydrocarbon receptor interacting protein mutations could predict first-generation SRL resistance. Patients with these characteristics may be better candidates for the GH receptor antagonist, pegvisomant, or in cases of large tumors the second-generation SRL, pasireotide. Combination therapy should be further pursued in patients who remain biochemically uncontrolled or have high remnant tumor after monotherapy. An efficacious and cost-effective pegvisomant dose-sparing effect of SRLs when used in combination has been demonstrated. With such a wide array of medical treatment options, it is increasingly important to tailor treatment to patients' unique characteristics as well as preferences, with a goal of personalizing management to achieve high quality outcomes.

Body Composition in Acromegaly According to Disease Activity - Performance of Dual X-Ray Absorptiometry and Multifrequency Bioelectrical Impedance Analysis

INTRODUCTION

the present study aims to evaluate body composition and its relationship with hormonal control in acromegaly, also comparing the performance of Bioelectrical impedance analysis (BIA), a more accessible method, with dual X-ray absorptiometry (DXA), technology frequently used in current studies.

METHODS

we studied 28 patients (78% female) of whom 13 with active disease, mean age was 52.11 ± 12.53 years; 64% had high blood pressure (HBP) and 50% had type 2 diabetes (T2D).

RESULTS

Although patients with controlled disease had lower serum GH (1.2 ± 1.68µg/L vs 6.61 ± 6.40µg/L, p=0.001) and IGF-1 (158.89 ± 54.53ng/mL and 503.31 ± 253.25ng/mL, p<0.001), they did not differ in body composition: percentage of fat mass: 36.13 ± 11.84% vs 37.73 ± 8.76%, p=0.691 for BIA and 37.10 ± 10.21% vs 37.89 ± 7.32%, p=0.819 for DXA; muscle mass parameters, BIA: FFMI 18.68 ± 2.38kg/m²vs 19.14 ± 1.59kg/m², p=0.560; SMI 10.17 ± 1.39kg/m²vs 10.53 ± 1.01kg/m², p=0.438; DXA: Baumgartner 7.99 ± 1.43kg/m²vs 8.02 ± 1.24kg/m², p=0.947, respectively for controlled and active disease. Patients with controlled acromegaly had lower fasting glucose (110.33 ± 55.48mg/dL vs 129.77 ± 40.17mg/dL, p=0.033) and were less likely to have persistent T2D (28.6 vs 71.4%, p=0.008) and HBP (38.9 vs 61.1%, p=0.049). There were strong positive correlations between BIA and DXA for fat mass (r=0.929, p<0.001) and muscle mass parameters: SMI X Baumgartner: r=0.890, p<0.001; and FFMI X Baumgartner: r=0.868, p<0.001.

CONCLUSION

our data showed similar results in body composition assessment by BIA and DXA, with good correlation between the methods, regardless of the hormonal status of acromegaly. Furthermore, in patients with adequate hormonal control, there was preservation of muscle mass and a lower prevalence of metabolic comorbidities, such as T2D and HBP.

Changes in Cross-Sectional Area of the Median Nerve and Body Composition Parameters after Treatment of Acromegaly: 1 year Follow-Up

OBJECTIVE

Median neuropathy is a common manifestation of acromegaly, although its pathology is uncertain. Changes in levels of growth hormone (GH) and insulin-like growth factor I (IGF-I) and body composition are potential parameters in pathology of median neuropathy in acromegaly. We aimed to assess changes in the cross-sectional area (CSA) of the median nerve and body composition in newly diagnosed acromegalic patients 1 year after treatment and to determine their mutual relationships.

DESIGN

This prospective study included 30 patients with newly diagnosed acromegaly and 30 healthy controls matched for age, gender, and body mass index. Physical and laboratory examinations, dual-energy X-ray absorptiometry (DXA), and ultrasound evaluations were performed at baseline and 1 year after initial treatment.

RESULTS

The CSA of the median nerve was increased in acromegalic patients compared with controls (13.1 mm² [12.2-14.9] vs 7.5 mm² [6.4-8.4], P < 0.001). One year after treatment of acromegaly, GH and IGF-I levels decreased significantly. The median nerve CSA was significantly reduced after treatment (11.6 mm² [10.2-13.1], P < 0.001). Reduction of IGF-I levels correlated with a decrease in lean mass and increase in fat mass. The median nerve CSA positively correlated with IGF-I levels (R = 0.492, P=0.006) and lean mass (R = 0.419, P=0.021) in acromegalic patients before treatment.

CONCLUSION

This study demonstrates a reduction in the median nerve CSA 1 year after treatment of acromegaly. These changes are closely associated with a reduction in IGF- I levels and in lean body mass. The enlargement of the median nerve in acromegaly can be reversed with adequate treatment.

[Discordant parameters of insulin-like growth factor 1 and growth hormone in the diagnosis and monitoring of acromegaly]

Acromegaly is a rare endocrine disorder associated with multiple complications and increased mortality. Timely diagnosis and adequate treatment can bring the life expectancy of patients with acromegaly closer to the general population level. The tests for the diagnosis of acromegaly are measurement of both serum GH, and GH after oral glucose administration; serum insulin-like growth factor-1 (IGF-1). However, in clinical practice, up to 39% of patients with discordant results are found. The patients with discordant GH and IGF-1levels, are the most difficult to manage. This review discusses the prevalence of discordant GH and IGF-1 outcomes in patients with acromegaly; factors causing this discrepancy; the impact of hormone levels on treatment outcomes. Although endocrinologists are used to dealing with this discrepancy in clinical practice for many years, discordant patients'outcome remains uncertain and undefined The optimal treatment should be individually tailored for each patient, taking into account all clinical parameters.

Pegvisomant treatment in acromegaly in clinical practice: Final results of the French ACROSTUDY (312 patients)

OBJECTIVE

We report the final analysis of the French ACROSTUDY, using data revised and enriched since the 2013 interim analysis. Our objective was to validate the use of pegvisomant (PEGV) in the treatment of acromegaly and to determine efficacy and safety.

PATIENTS AND METHODS

Patients with acromegaly treated with PEGV and followed up for at least 5 years were included. Eighty-eight investigators from 62 clinical centers in France included patients from April 2007 to April 2014. PEGV dose and administration frequency were determined by the physicians, based on their clinical evaluation and local habits. No additional examinations beyond those performed in normal follow-up were required. Minimum recommended follow-up included check-ups at treatment initiation, 6 months, 12 months and then annually.

RESULTS

In total, 312 patients were enrolled. Mean age was 46.1±14.3 years at introduction of PEGV. Median PEGV treatment duration was 6.3 years and median follow-up was 5.6 years. Median dose at initiation was 10mg/day. The percentages of patients with IGF-1 ≤ ULN (upper limit of normal) were 10% (n=300) at baseline, 54% at 6 months (n=278), and 61.7% (n=253) at 2 years, then stabilizing at 64.4% (n=180) at 5 years. Mean PEGV dose was 17.4±11.7mg in patients with controlled disease versus 21.1±17.3mg in those without control at 5 years. At 5 years, 21.8% of patients (54/248) were receiving >30mg PEGV per day. In patients with at least one pituitary imaging procedure during the 5-year follow-up (n=292), the most recent image showed stable tumor volume in 212 subjects (72.6%), increased volume in 13 (4.5%), and decreased volume in 30 (10.3%). No PEGV treatments were permanently discontinued due to transaminase elevation. There were no cases of liver failure.

CONCLUSION

The French ACROSTUDY showed normalization of IGF-1 levels in 64.4% of a real-life cohort of patients, mostly with uncontrolled disease despite multiple prior therapies. Long-term follow-up showed a sustained effectiveness and good long-term safety.

Transient Permeation Enhancer® (TPE®) technology for oral delivery of octreotide: a technological evaluation

INTRODUCTION

The FDA approval of oral semaglutide for type 2 diabetes (2019) and oral octreotide for acromegaly (2020) is evidence that selected niche peptides can be administered orally if formulated with selected intestinal permeation enhancers.

AREAS COVERED

We evaluated the oral octreotide formulation, MYCAPSSA® (Chiasma Pharmaceuticals, Needham, MA, USA). An outline of the current standard of care in acromegaly and the benefits of oral octreotide versus depot injections is provided. We discuss the Transient Permeation Enhancer (TPE®) technology used and detail the safety and efficacy data from animal models and clinical trials.

EXPERT OPINION

TPE® is an oily suspension of octreotide that includes a number of excipients that can transiently alter epithelial barrier integrity by opening of intestinal epithelial tight junctions arising from transcellular perturbation. Phase I studies using 20 mg octreotide capsules yielded a relative oral bioavailability of ~0.7% and primary endpoints were achieved in two Phase III studies. The oral octreotide dose required to achieve these endpoints was over 200 times that of the 0.1 mg immediate-release subcutaneous injection, a reminder of the difficulty in achieving oral absorption of macromolecules. Many acromegaly patients will prefer a convenient twice-daily oral formulation of octreotide compared to monthly depot injections.