Growth Hormone Receptor Research Articles

Cephalgic syndrome in patients with acromegaly

The aim of this review is to summarize the data available in the literature on the causes of headache in patients with acromegaly, as well as on the effect of various methods of acromegaly treatment on headache. Publications were searched in the PubMed database using the keywords «Headache in patients with acromegaly», «Headache in patients with pituitary adenomas», «Tension-type headache», «Migraine». Headache in patients with pituitary adenomas secreting somatotropic hormone (STH) is not uncommon: according to various authors, cephalgic syndrome occurs in 30-70% of patients with acromegaly and can worsen their quality of life, along with other factors, up to disability. By the nature of development, headache with acromegaly is classified into primary (migraine, tension headache, trigeminal autonomic cephalgia, for example, SUNCT syndrome and cluster headaches), and can also be caused by various causes directly related to the tumor. All this requires differential diagnosis. The factors causing headaches in somatotropinomas have not yet been well studied and require further research. These include the mass effect of the tumor, hormonal hypersecretion, pathology of the temporomandibular joint, sodium and fluid retention in the body, psychological factors, etc. The authors evaluated the effect on headache of various methods of acromegaly treatment: transnasal transsphenoidal adenomectomy, radiation therapy and drug therapy with somatostatin analogues, dopamine agonists and growth hormone receptor antagonist. However, even when normal levels of STH and insulin-like growth factor 1 (IGF-1) are reached, cephalgic syndrome may persist, therefore patients should be warned about this in advance and referred to a cephalgologist to select adequate headache therapy.

Site-Selective Zwitterionic Poly(caprolactone-carboxybetaine)-Growth Hormone Receptor Antagonist Conjugate: Synthesis and Biological Evaluation.

Zwitterionic polymers have been found to be biocompatible alternatives to poly(ethylene glycol) (PEG) for conjugation to proteins. This work reports the site-selective conjugation of poly(caprolactone-carboxybetaine) (pCLZ) to human growth hormone receptor antagonist (GHA) B2036-alkyne and investigation of safety, activity, and pharmacokinetics. Azide-end-functionalized pCLZs were synthesized and conjugated to GHA B2036-alkyne via copper-catalyzed click reaction. The resulting inhibitory bioactivity concentration responses in Ba/F3-GHR cells were compared to those of PEGylated GHA B2036. IgG and IgM antibody production was tested in mice, and no measurable antibody or cytokine production was detected for the pCLZ conjugate. Using 18F-labeled PET/CT imaging, the pCLZ conjugate showed an increase in circulation time compared to that of GHA B2036. Acute toxicity of the polymer was investigated in vivo and found to be nontoxic. Ex vivo degradation of the polymer on the conjugate was investigated. The results suggest that pCLZ-GHA is a potentially safe alternative to PEG-GHA.

Running in mice increases the expression of brain hemoglobin-related genes interacting with the GH/IGF-1 system

The beneficial effects of exercise are partly mediated via local or systemic functions of the insulin-like growth factor-1 (IGF-1) system. As IGF-1 increases local brain hemoglobin beta (Hbb) transcripts, we hypothesized that exercise could have similar effects. Mice were single-housed with free access to running wheels for seven days. After sacrifice and saline perfusion, the expression of 13 genes was quantified using real-time quantitative polymerase chain reaction (RT-qPCR) in three brain regions: the prefrontal cortex, motor cortex, and hippocampus. In addition, plasma insulin, glucose, homeostatic model assessment of IR (HOMA-IR), C-peptide, and IGF-1 were investigated. We show that hemoglobin-related transcripts (Hbb and 5’-aminolevulinate synthase 2 [Alas2]) increased 46–63% in the running group, while IGF-1-related genes [Igf1 / growth hormone receptor (Ghr)] decreased slightly (7%). There were also moderate to large correlations between Hbb- and IGF-1-related genes in the running group but not in the sedentary group. HOMA-IR, plasma glucose, and insulin changed marginally and non-significantly, but there was a trend toward an increase in plasma-IGF-1 in the running group. In conclusion, seven days of running increased Hbb-related transcripts in three brain regions. Hbb-related transcripts correlated with components of the brain IGF-1 system only in the running group.

The Pattern of Gene Expression (Igf Family, Muscle Growth Regulatory Factors, and Osteogenesis-Related Genes) Involved in the Growth of Skeletal Muscle in Pikeperch (Sander lucioperca) During Ontogenesis

The pikeperch (Sander lucioperca) is an economically important freshwater fish and a valuable food with high market acceptance. It is undergoing important changes in growth and regulatory metabolism during the ontogeny. Hence, the current study aims to investigate the mRNA expression of the growth hormone (gh)/insulin-like growth factor (igf) axis (ghr, igfI, igfbp, igfr), muscle regulatory factors (pax7, myf5, myod, myogenin, mrf, mymk, mstn), and osteogenesis-related genes (colla1a, fib1a, on, op, ostn) from hatching through day 40th post-hatching (DPH). The average total length (TL) of larvae measured at hatching was 3.6 ± 0.4 mm (67 degree days), and at the end of the experiment (40 DPH, 777 degree days), it was 27.1 ± 1.1 mm. The results showed three phases of gene expression in day 0 (egg), larval, and juvenile stages of pikeperch, which can be a progression or transition from the initial state toward the juvenile state. The expression pattern of myf5, mymk, and fib1a genes showed the highest value at day 0. The growth hormone receptor gene (ghr) and igfbp5 were raised to 1 DPH, whereas increased expression of igfI, igfII, igf1bp4, igf1rb, myod2, and mrf4 was detected at 14 DPH. The myod1, pax7, op, ostc, on, igf1ra, and col1a1a genes were highly expressed at 21 DPH and juvenile stages. According to the PLS-DA model, the most relevant VIPs are myf5 and mymk as best markers of earlier stages and igf1ra, ostc, pax7, and ghr as markers of later stages of ontogeny. Results from this study suggest that basal metabolism, growth of body cells and muscles, and bone proliferation and development can be regulated by the dynamic changes in gene expression patterns in this species. The identified genes will help to understand the basic biological process of pikeperch larvae and development, which is very important in pikeperch farming

Characterization and Regulation of the Neonatal Growth Hormone Surge.

High neonatal growth hormone (GH) secretion has been described in several species. However, the neuroendocrine mechanisms behind this surge remain unknown. Thus, the pattern of postnatal GH secretion was investigated in mice and rats. Blood GH levels were very high on postnatal day (P)1 and progressively decreased until near zero by P17 in C57BL/6 mice without sex differences. This pattern was similar to that observed in rats, except that female rats showed higher GH levels on P1 than males. In comparison, follicle-stimulating hormone exhibited higher secretion in females during the first 3 weeks of life. Hypothalamic Sst mRNA and somatostatin neuroendocrine terminals in the median eminence were higher in P20/P21 mice than in newborns. Knockout mice for GH-releasing hormone (GHRH) receptor showed no GH surge, whereas knockdown mice for the Sst gene displayed increased neonatal GH peak. Leptin deficiency caused only minor effects on early-life GH secretion. GH receptor ablation in neurons or the entire body did not affect neonatal GH secretion, but the subsequent reduction in blood GH levels was attenuated or prevented by these genetic manipulations, respectively. This phenotype was also observed in knockout mice for the insulin-like growth factor-1 (IGF-1) receptor in GHRH neurons. Moreover, glucose-induced hyperglycemia overstimulated GH secretion in neonatal mice. In conclusion, GH surge in the first days of life is not regulated by negative feedback loops. However, neonatal GH secretion requires GHRH receptor, and is modulated by somatostatin and blood glucose levels, suggesting that this surge is controlled by hypothalamic-pituitary communication.

In Vivo Effects of a GHR Synthesis Inhibitor during Prolonged Treatment in Dogs

Background: The activation of the growth hormone receptor (GHR) is a major determinant of body growth. Defective GHR signaling, as seen in human Laron dwarfism, resulted in low plasma IGF-1 concentrations and limited growth, but also marked absence in the development of breast cancer and type 2 diabetes. In vitro, we identified a small molecule (C#1) that inhibits the translation of GHR mRNA to receptor protein. Methods: Before its application in humans as a potential anticancer drug, C#1 was tested in animals to evaluate whether it could be administered to achieve a plasma concentration in vivo that inhibits cell proliferation in vitro without causing unwanted toxicity. To evaluate the efficacy and toxicity of C#1, a group of six intact female Beagle dogs was treated daily each morning for 90 days with an oral solution of C#1 in Soiae oleum emulgatum at a dose of 0.1 mg/kg body weight. During treatment, dogs were closely monitored clinically, and blood samples were taken to measure plasma C#1 concentrations, complete blood counts (CBC), clinical chemistry, and endocrinology. At the end of the treatment, dogs were euthanized for gross and histopathological analysis. An additional group of six female Beagle dogs was included for statistical reasons and only evaluated for efficacy during treatment for 30 days. Results: Daily administration of C#1 resulted in a constant mean plasma concentration of approximately 50 nmol/L. In both groups, two out of six dogs developed decreased appetite and food refusal after 4–5 weeks, and occasionally diarrhea. No significant effects in CBC or routine clinical chemistry were seen. Plasma IGF-1 concentrations, used as biomarkers for defective GHR signaling, significantly decreased by 31% over time. As plasma growth hormone (GH) concentrations decreased by 51% as well, no proof of GHR dysfunction could be established. The measured 43% decrease in plasma acylated/non-acylated ghrelin ratios will also lower plasma GH concentrations by reducing activation of the GH secretagogue receptor (GHSR). C#1 did not directly inhibit the GHSR in vivo, as shown in vitro. There were no significant effects on glucose, lipid, or folate/homocysteine metabolism. Conclusions: It is concluded that with daily dosing of 0.1 mg C#1/kg body weight, the induction of toxic effects prevented further increases in dosage. Due to the concomitant decrease in both IGF-1 and GH, in vivo inhibition of GHR could not be confirmed. Since the concept of specific inhibition of GHR synthesis by small molecules remains a promising strategy, searching for compounds similar to C#1 with lower toxicity should be worthwhile.

7145 Enhanced Ability of the Small Peptide GH Receptor Antagonist, AZP-3813, to Decrease IGF1 When Combined with the Somatostatin Analog, Octreotide

Abstract Disclosure: G. Ravel: None. C. Berardet: Employee; Self; Amolyt Pharma. C. Chalmey: Employee; Self; Amolyt Pharma. H. Kurasaki: Employee; Self; Peptidream Inc. T. Tomiyama: Employee; Self; Peptidream Inc. P. Reid: Employee; Self; Peptidream Inc. D. Duracher: Employee; Self; Amolyt Pharma. R. Datta: Consulting Fee; Self; Amolyt Pharma. M. Aouadi: Employee; Self; Amolyt Pharma. M.D. Culler: Employee; Self; Amolyt Pharma. There is a strong rationale for combining a growth hormone (GH) receptor antagonist (GHRA) with somatostatin analog (SSA) therapy for acromegalic patients. While SSAs are the primary medical therapy for treatment of acromegaly, insulin-like growth factor 1 (IGF1) levels fail to normalize with SSA monotherapy in most patients. Even in patients with controlled IGF1, GH levels can remain elevated and induce symptoms by interacting with GH receptors throughout the body. In addition, while GHRAs have no significant effect on the causative pituitary tumor, SSAs can often induce tumor stabilization or shrinkage. AZP-3813 is a 16-amino acid, bicyclic peptide GHRA which has been demonstrated to potently decrease IGF1 in both rats and dogs. In order to examine the effect of combining AZP-3813 with a SSA in decreasing IGF1, 8-week old, male, Sprague Dawley rats were implanted subcutaneously with Alzet model 2002 minipumps containing either vehicle or the SSA, octreotide (OCT), at concentrations required to deliver either 20 or 40μg OCT/kg/day. Blood samples for IGF1 measurement were collected before, and 48 and 72 hours after pump implantation. Immediately following the 72-hour blood collection, rats from each infusion group were injected subcutaneously with either vehicle or AZP-3813 at 0.3, 1, 3, 10 or 30mg/kg (n=7/group). A subsequent blood sample was collected 24 hours after the injection of vehicle or AZP-3813, which also corresponded to 96 hours after pump implantation. Plasma levels of IGF1 were assessed by radioimmunoassay. In rats infused with vehicle, the 0.3mg/kg dose of AZP-3813 had no effect on IGF1 as compared with baseline; however, with higher doses a clear, dose-related decrease in IGF1 was observed ranging from -7 ± 3.0% with 1mg/kg AZP-3813 to -29 ± 2.0% with 30mg/kg. OCT infusion alone at 20μg/kg/day produced a -10 ± 3.6% decrease in IGF1, while injection of AZP-3813 into rats infused with 20μg/kg/day OCT, produced an enhanced, dose-related decrease, ranging from -7 ± 3.8% with 0.3mg/kg AZP-3813 to -38 ± 3.4% with 30mg/kg. A clear additive relationship was observed by focusing on the 3mg/kg dose of AZP-3813, which, alone, decreased IGF1 by -13 ± 2.8% in vehicle-infused rats. When injected into rats infused with OCT, which alone decreased IGF1 by -10 ± 3.6%, a combined decrease of -23 ± 3.3% was observed. The magnitude of the combined decrease was not statistically different from the decrease obtained with 30mg/kg AZP-3813 alone in vehicle-infused rats; thus, demonstrating a 10-fold increase in the effectiveness of AZP-3813 when combined with OCT. Similar results were observed with 40μg/kg/day OCT infusion. These results demonstrate the enhanced efficacy of AZP-3813 in decreasing IGF1 when combined with the SSA, OCT, and support the development of AZP-3813 as an add-on therapy in patients inadequately controlled with SSA treatment. Presentation: 6/3/2024

6459 A Novel Long-Acting GH Receptor Antagonist Optimizing Therapeutic Efficacy and Duration

Abstract Disclosure: C. Ku: None. C. Kang: None. J. Oh: None. E. Wang: None. H. Song: None. K. Park: None. B. Kim: None. K. Kim: None. S. You: None. S. Park: None. E. Lee: None. Background: Forty to sixty percent of acromegalic patients undergo medical treatment, utilizing somatostatin analogues, dopamine agonists, and GH receptor (GHR) antagonists. The GHR antagonist, pegvisomant exhibits the most robust efficacy in reducing IGF-1 levels in acromegalic patients. However, pegvisomant faces several clinical limitations, such as poor compliance due to the necessity of daily injections. This study aimed to develop a novel, long-acting fusion GHR antagonist with optimized therapeutic efficacy and duration. Method: Twelve mutant proteins with alterations in the C-terminal and N-terminal regions of GHR were generated to confirm the GHR binding affinity and inhibitory potency compared with pegvisomant, which was evaluated with STAT5b luciferase reporter assay. Several carriers were engineered into selected mutant GHRs to increase the therapeutic duration. For in vivo experiments, single or repetitive injection of GHR antagonists were applied to acromegalic mouse model (somatotroph specific Aip knock out (sAIPKO) mice). Pharmacokinetics (PK) and pharmacodynamics (PD) were evaluated in New Zealand White (NZW) rabbits. Result: Four out of the 12 GHR mutants exhibited higher affinity and stronger inhibitory potency toward human GHR when compared to pegvisomant. Specifically, three GHR mutants significantly reduced serum IGF-1 levels in sAIPKO mice following daily injections of 20 mg/kg for 7 days (52.3±6.0 to 5.9±1.3, 50.3±3.5 to 32.3±2.3, and 49.8±3.7 to 13.9±4.3 ng/mL; all p < 0.05). Among them, S4020N exhibited the lowest EC50 value for GHR binding affinity in in vitro analysis containing human GHR (0.594 nM) and mouse GHR (0.891 nM). Following fusion with each long-acting carrier, S4020N with the Fc carrier protein (ALT-B5) demonstrated the highest binding affinity and the strongest inhibitory potency toward human GHR, surpassing pegvisomant by 14 and 25 times, respectively. Administration of ALT-B5 (80 mg/kg) and pegvisomant (24 mg/kg) at a 3-day interval revealed the superior efficacy of ALT-B5 over pegvisomant (1879±219.4 vs. 3800±355.9 ng*hr/mL IGF-1 AUC for 5 days in ALT-B5 and pegvisomant, respectively; p < 0.01). In PK/PD studies, ALT-B5 was administered at doses of 3 mg/kg and 10 mg/kg in NZW rabbits, and PK/PD parameters were compared with the same molar concentration of pegvisomant. ALT-B5 exhibited the longest therapeutic duration and the highest efficacy compared to pegvisomant. Conclusion: ALT-B5 exhibited the longest duration and highest effectiveness in lowering IGF-1 levels. ALT-B5 emerges as a potential novel therapeutic option for acromegaly. Presentation: 6/1/2024

8026 Growth Hormone Receptor (GHR) is Independently Associated with Body Composition and Glycemic Measures in Youth with Type 2 Diabetes (T2D)

Abstract Disclosure: C. Lu: None. D. Wolfs: None. L. El ghormli: None. L.M. Laffel: None. M. Patti: Advisory Board Member; Self; Fractyl Health. Consulting Fee; Self; AstraZeneca, Hamni, MBX Biosciences. Grant Recipient; Self; Dexcom. E. Isganaitis: None. Background: T2D is more severe in youth than in adults, with growth and puberty as potential drivers. Growth hormone (GH) action, which peaks during puberty, also regulates carbohydrate metabolism. We previously showed that higher plasma levels of GHR are associated with hyperglycemia, insulin resistance, and decreased insulin secretion in youth with T2D. Plasma GHR is higher in obesity, and reductions in GHR after bariatric surgery may mediate improvements in glycemia. The association of GHR with body composition in youth with T2D has not been previously studied. Hypothesis: We hypothesize that the association of GHR with glycemic outcomes in youth with T2D is mediated by differences in body composition, and that associations between GHR and body composition differ by sex. Methods: Utilizing plasma samples from Treatment Options for Type 2 Diabetes in Adolescents and Youth (TODAY) study (N=398), we examined association of plasma GHR (ELISA; ng/mL) with a) body composition measures including zBMI, absolute lean mass (kg), percent body fat (dual-energy x-ray absorptiometry), and b) glycemic outcomes including hemoglobin A1c (HbA1c), fasting glucose (mg/dL), 1/fasting C-peptide (mL/ng), C-peptide index (ng/mL per mg/dL), and C-peptide oral disposition index (CODI; mL/uU x ng/mL per mg/dL), stratified by sex. Linear regressions were adjusted for age, race/ethnicity, and Tanner stage in the base models, with additional adjustments for HbA1c, zBMI, lean mass, or percent fat. Results: This subcohort of youth with T2D from the TODAY study included 150 males and 248 females, mean age 13.9 ± 2.0 years. Females had lower zBMI (+2.2 ± 0.4 vs. +2.3 ± 0.5, p=0.005), lower lean mass (51 ± 10 vs. 59 ± 14, p<0.001), and higher percent body fat (39 ± 5 vs. 34 ± 6, p<0.001). Higher log2 GHR was associated with higher zBMI (B=0.44, SE=0.04, p<0.001), higher lean mass (B=4.3, SE=1.2, p<0.001), and higher percent fat (B=4.4, SE=0.7, p<0.001), even after adjustment for HbA1c, and without sex-specific differences. Higher log2 GHR was associated with higher HbA1c (B=0.35, SE=0.08, p<0.001), higher fasting glucose (B=9.0, SE=2.6, p<0.001), lower 1/fasting C-peptide (B=-0.17, SE=0.01, p<0.001), and lower CODI (B=-0.001, SE=0.001, p=0.02). These associations did not change with further adjustments for zBMI, lean mass, or percent fat, suggesting that associations between GHR and glycemia are independent of obesity or body composition. In analyses stratified by sex, the effect of GHR on CODI was attenuated after adjustment for lean mass in males only. Conclusion: Plasma GHR is independently associated with body composition and glycemia in youth with T2D. There were no sex differences in associations of GHR with HbA1c and insulin resistance. However, the association of GHR with beta cell function may be mediated by lean mass in boys but not in girls, although power was more limited in the sex-stratified analyses. Presentation: 6/3/2024

8396 Growth Hormone Secretion after Glucagon Stimulation is Increased in Individuals with History of Bariatric Surgery

Abstract Disclosure: L. Pei: None. C. Cummings: None. H. Saeed: None. M. Farahmandsadr: None. A. Amore: None. A. Sheehan: None. R. Ferraz-Bannitz: None. D.C. Simonson: Stock Owner; Self; GI Windows. Other; Self; wife owns Phase V Technologies. M. Patti: Advisory Board Member; Self; data and safety monitoring board on Fractyl Health. Consulting Fee; Self; AstraZeneca, Hamni, MBX Biosciences. Grant Recipient; Self; Receive investigator-initiated research funding from Dexcom. Background: Growth hormone (GH) is an important counterregulatory hormone and regulator of hepatic glucose metabolism. Previous studies demonstrated increased plasma GH and reduced plasma growth hormone receptor (GHR) after bariatric surgery in both rodents and humans. Moreover, plasma GHR was identified as mediator of improved glycemic control after Roux-en-Y gastric bypass (RYGB). We now test the hypothesis that altered GH and/or GHR levels contribute to post-bariatric hypoglycemia (PBH). Methods: Cross-sectional studies were performed at a single academic institution. GH secretion was assessed after 1mg IV glucagon (GCG) and during hyperinsulinemic-hypoglycemic clamp in 3 groups: 1) post-RYGB without hypoglycemia symptoms (RnonH) (20F, age 51±11 (mean±SD) y, BMI 35±8 kg/m2, HbA1c 5.2±0.3%, 10.6±5.3 years post-surgery), 2) PBH (18F/2M, age 54±12y, BMI 30.5±4.6 kg/m2, HbA1c 5.2±0.3%, 9.4±6.0 years post-surgery), 3) weight-similar controls without upper GI surgery (CON) (6F/4M, age 47.1±13.1y, BMI 31.9±5.7 kg/m2, HbA1c 5.4±0.3%). Plasma GHR and GH were measured via ELISA. Results: Fasting GH did not differ between groups (mean±SE, CON: 285±78, RnonH: 860±179, PBH: 980±284 pg/mL, P=0.16). Peak incremental glucose response to GCG, ranging from 46-59 mg/dL, did not differ between groups. At 120 min after GCG, GH was significantly higher in both PBH and RnonH vs. CON (PBH: 3018±678, RnonH: 2521±656, CON: 481±137 pg/mL, ANOVA P= 0.012, PBH vs. CON P=0.003, RnonH vs. CON P=0.02). Peak GH in PBH was significantly higher vs. CON (3431± 655 vs. 547±153 pg/mL, P=0.03), but did not differ in RnonH vs. PBH. Peak GH was inversely correlated with postoperative duration in PBH only (r=-0.49, P=0.03), with BMI in both surgical groups (PBH: r=-0.49, P=0.03, RnonH: r=-0.57, P=0.009) and with percent body fat (impedance plethysmography) in the combined surgical group (r=-0.51, P=0.0007). In contrast, GH during hyperinsulinemic hypoglycemia did not differ between groups (CON: 9660 ±2588, RnonH: 7759±1751, PBH: 7309±1549 pg/mL, P=0.3) at similar degrees of hypoglycemia (CON: 54.8±1.5, RnonH: 50.7±1.0, PBH: 50.9±1.4 mg/dL). Fasting plasma GHR did not differ (CON: 23.3±3.8, RnonH: 19.4±2.8, PBH: 13.8±2.1 ng/mL, P=0.10). GHR was correlated with percent fat mass in the combined surgical group (r=0.56, P=0.0003) but not in CON. Conclusion: Plasma GH did not differ as a function of prior RYGB, with or without hypoglycemia, in the fasting state or in response to insulin-induced hypoglycemia. However, GCG-stimulated GH levels were 5-6-fold higher in individuals with history of RYGB, numerically higher in PBH, and inversely related to body fat and postop duration. Together these results suggest that reduced GH is not likely driving hypoglycemia in PBH, but that alterations in glucagon-mediated GH secretion and/or action may contribute to observed metabolic effects of RYGB. Presentation: 6/1/2024

8406 A Phase 1 Clinical Study to Evaluate the Safety, Tolerability, Pharmacokinetics and Pharmacodynamics of AZP-3813, a Novel Small Peptide Growth Hormone Receptor Antagonist, in Healthy Subjects

Abstract Disclosure: S. Allas: Employee; Self; Amolyt Pharma. Stock Owner; Self; Amolyt Pharma. G. Ravel: Employee; Self; Amolyt Pharma. Stock Owner; Self; Amolyt Pharma. C. Farrell: Employee; Self; ICON plc. S. Fillon: Employee; Self; Amolyt Pharma. O. Taha: Employee; Self; Amolyt Pharma. M.D. Culler: Employee; Self; Amolyt Pharma. Stock Owner; Self; Amolyt Pharma. M. Ovize: Employee; Self; Amolyt Pharma. Stock Owner; Self; Amolyt Pharma. M. Sumeray: Employee; Self; Amolyt Pharma. Stock Owner; Self; Amolyt Pharma. A.J. Van der Lely: Consulting Fee; Self; Amolyt Pharma. Acromegaly is a rare disease typically caused by a benign growth hormone (GH)-secreting pituitary adenoma that stimulates over-production of insulin-like growth factor-1 (IGF1) from the liver. Treatment with somatostatin analog (SSA) monotherapy does not provide optimal control of circulating IGF-1 levels in the majority of patients. AZP-3813, a 16-amino acid, bicyclic GH receptor antagonist (GHRA) binds to the GH receptor and prevents endogenous GH from stimulating the production of IGF-1. The compound is being developed as an add-on therapy for the treatment of acromegaly in patients insufficiently controlled with SSAs. In normal animals, AZP-3813 potently decreases circulating levels of IGF-1 and further suppressive effects are observed when combined with the SSA, octreotide. Randomized double-blind placebo-controlled single and multiple ascending dose studies (SAD and MAD, respectively) are being conducted to evaluate the safety, tolerability, pharmacokinetics (PK) and pharmacodynamics (PD) of AZP-3813 in healthy subjects. Here we report data from all SAD cohorts and the first 3 MAD cohorts. In the SAD study, 5 subjects received a single subcutaneous administration of 3 mg AZP-3813 or placebo (3:2) and 8 subjects received 10, 20, 40, 60, 90, 120 mgAZP-3813 or placebo (6:2). In the MAD study, 8 subjects received 10, 20, 40 mg AZP-3813 or placebo (6/2) QD for 14 consecutive days. In both SAD and MAD studies, treatment was well tolerated in all subjects with no safety concerns. Cmax and AUC increased in a dose-proportional manner. The half-life of AZP-3813 was estimated to be 18-22 hours. In the SAD study, AZP-3813 induced a dose-related decrease in circulating IGF-1 levels at doses of 10 mg and above with a more prolonged reduction up to 72 hours at higher doses. In the MAD study, AZP-3813 induced a gradual and sustained dose-related decrease in circulating IGF-1 levels at 20 and 40 mg/day, with a larger effect after 2 weeks of dosing as compared to single administration at the same dose, consistent with a cumulative effect of repeated administration. Mean placebo-adjusted % change from baseline for the 20 and 40 mg cohorts were 19% and 44%, respectively. This study is ongoing, and updates on additional MAD cohorts will be reported at the meeting. These data clearly demonstrate that AZP-3813, the novel GHRA, substantially decreases circulating IGF-1 levels in healthy individuals, thereby supporting further testing in patients with acromegaly. Presentation: 6/1/2024

8649 Ablation of Leptin Receptors in Somatotropes Impacts Transcriptomic Plasticity in the Pou1f1 Lineage of Female Pituitary Cells

Abstract Disclosure: T.K. Miles: None. A.K. Odle: None. S. Byrum: None. A. Lagasse: None. A. Haney: None. V.G. Ortega: None. A. Herdman: None. M.C. MacNicol: None. A.M. MacNicol: None. G.V. Childs: None. Anterior pituitary somatotropes produce growth hormone (GH) to optimize body composition, receiving tropic signals from leptin about the metabolic state. When leptin receptors are ablated in somatotropes, GH proteins, serum GH and GHRH receptors are reduced. Unexpectedly, POU1F1, Prolactin, and TSH-beta proteins are also reduced in pituitaries of Somatotrope LEPR-null females (mutants), suggesting a tropic role for leptin in differentiation. To test this hypothesis, single cell RNA-seq analysis compared the pituitary transcriptome of 6-month-old control and mutant female mice housed under thermoneutral conditions (28°C). Following scRNA-seq, cells were clustered computationally with the use of Seurat; all cell types were identified in separate UMAP clusters. Mutants showed increases in cell numbers in somatotrope (4.7X) and Pou1f1 (5.7x) clusters, but no change in thyrotrope or lactotrope clusters. In LEPR-null female somatotropes, the 516 differentially expressed genes (DEGs; adj p<0.05) included upregulated Pomc, Prl, Lhb, Tshb and Cga (Log2FC+0.5-1.7) and downregulated Pou1f1, Ghrhr, and Gh (Log2FC -0.5—1.5). In the lactotrope cluster from mutants, Pomc, Cga, and Gh were upregulated (Log2FC+1.1-1.5) and Pou1f1 and Prl were downregulated. The thyrotrope cluster was unchanged. Prl, Pomc, and Gh were upregulated in the Pou1f1 cluster. The down regulation of Gh, Pou1f1, and Ghrhr in somatotropes and Prl in lactotropes correlates with the lower serum levels of GH and Prl in mutant females. However, the upregulated DEGs do not correlate with increased secretory activity suggesting that the multihormonal cells are not fully functional. This was confirmed with Ingenuity Pathway Analysis (IPA) showing downregulation of canonical pathways involved in secretion in mutant somatotropes. Unexpectedly, mutant females exposed to a HFD (60% fat) for 16 weeks (+16.6g) showed a reversal of the changes in somatotrope cell numbers and multihormonal expression seen in control fed mutants. The increase in genes belonging to IPA canonical cytoplasmic translation pathways in mutant somatotropes were also completely reversed following a HFD. Furthermore, the downregulated secretory/signaling pathways seen in control fed mutant female somatotropes and lactotropes (endocytosis, vesicle transport, Gaq, GnRH) were upregulated modestly following a HFD. The high serum leptin in the HFD fed mutant mice may activate signaling pathways in cells still expressing LEPR. Collectively, these results confirm a role for leptin in maintaining differentiated somatotropes. They also suggest that leptin may limit expansion of multihormonal progenitor cells. The decreased multihormonal expression and protein synthesis in lactotrope clusters from mutant mice exposed to a HFD are also seen in lactotropes from control mice on a HFD, which suggests that a HFD may compromise pituitary plasticity. Presentation: 6/3/2024

6367 Growth gone Awry: A Rare Case of Acromegaly in a 16-Year-Old Female with Panhypopituitarism Secondary to Craniopharyngioma on Low Doses of Growth Hormone with Low IGF-1 levels

Abstract Disclosure: L.M. Ayala Castro: None. J. Ye Tay: None. A. Diaz: None. This report highlights a rare case of a 16-year-old female with panhypopituitarism due to craniopharyngioma, where GH replacement therapy triggered acromegaly features despite having low IGF-1 levels. Background: Craniopharyngiomas are the most common tumors causing acquired pituitary deficiencies in children. Various mechanisms contribute to acromegaly, and hypersensitivity to hormonal treatment in this benign tumor emerges as a plausible avenue for investigation. Case Presentation: A 16-year-old female diagnosed with craniopharyngioma at age 5 developed secondary panhypopituitarism. Baseline hormonal profiles indicated markedly reduced levels of IGF-1 and insulin growth factor–binding protein 3 (IGF-BP3). Despite the established condition, GH treatment was initiated at age 8 for potential growth and development benefits. Before commencing GH therapy, a bone age assessment revealed normal skeletal development. However, GH replacement therapy led to an unexpectedly robust response, resulting in physical changes consistent with acromegaly. Paradoxically, laboratory evaluations showed low IGF-1 levels. Imaging studies, including pituitary MRI, ruled out new abnormalities or tumors. As the patient approached peak adult height at 16, having been on adult GH therapy since age 13, a decision was made to discontinue GH replacement therapy and address acromegaly symptoms. Frequent follow-up visits were planned to assess growth velocity, monitor hormonal levels, and evaluate potential adverse effects. Discussion: This case demonstrates an unusual sensitivity to exogenous GH, resulting in an exaggerated response contrary to expected IGF-1 elevation. Atypical IGF-1 levels may suggest alterations in liver physiology, GH receptor signaling pathways (e.g., Laron Syndrome), or downstream defects in IGF-1 synthesis. Further research is crucial to elucidate the underlying mechanisms. Conclusion: Only 3 cases of acromegaly as a side effect of GH replacement therapy have been reported in the literature. We report a further case that underscores the complexity of managing hormonal imbalances, especially in unique patient populations with panhypopituitarism secondary to craniopharyngioma. The unexpected response to GH treatment emphasizes the need for individualized approaches and vigilant monitoring.

Combined Dietary Spirulina platensis and Citrus limon Essential Oil Enhances the Growth, Immunity, Antioxidant Capacity and Intestinal Health of Nile Tilapia.

The dietary presence of feed additives is crucial for boosting fish growth and immunity. Accordingly, this feeding trial aimed to investigate the effects of the separate and concurrent dietary supplementation of Spirulina platensis (SP) and bitter lemon (Citrus limon) peel essential oil (LEO) on the growth, immunity, antioxidant capacity, and intestinal health of Nile tilapia (Oreochromis niloticus). Four groups of male Nile tilapia were employed. The first group (control) was given the basal diet, while the second and third groups received the basal diet supplemented with LEO extract (1%) and SP (1 g/kg diet), respectively. The fourth group received the basal diet supplemented with a mix of LEO (1%) and SP at 1 g/kg. After two months of feeding, using LEO or/and SP improved the overall growth and immunological parameters, with their combination yielding the best outcomes. The supplementation of LEO or/and SP improved the Nile tilapia's growth metrics and transcriptomic levels of growth-regulating genes such as (oligo-peptide transporter 1 (Pep1), growth hormone receptors 1 (GHR1), and insulin-like growth factor (IGF1). The improved growth performance was linked to significant increases in the expression levels of mucin and fat metabolism-related genes. Moreover, fish supplemented with LEO, SP, or their combination showed enhanced non-specific immunological measures, including phagocytic and lysozyme activities and the mRNA copies of its regulating genes. Additionally, remarkable increases in the antioxidant enzyme activities and the mRNA levels of their related genes were detected. The complement (C3) gene's transcriptomic level was also significantly increased. Furthermore, the dietary supplementation of LEO, SP, or their combination improved the histological structures of the spleen, hepatopancreas, and intestine. The enhanced effects of LEO, SP, or their combination on fish immunity and growth are suggested to be due to their contents of bioactive compounds with anti-inflammatory, antioxidant, and antimicrobial properties. Thus, using the LOE and SP blends as feed additives is recommended for better growth and immunity of Nile tilapia.

Race/ethnicity and human epidermal growth hormone receptor 2–targeted therapy for breast cancer.

91 Background: Breast cancer is the most common cancer in the US. Up to 25% of breast cancers are classified as human epidermal growth factor receptor 2 (HER2)-positive and associated with an aggressive tumor burden. HER2-targeting monoclonal antibodies improves survival in patients with HER2-positive breast cancer. Prior work has demonstrated disparities in access to oncologic therapies among older women. Our study seeks to examine racial/ethnic disparities in receiving HER2-targeted therapies for patients with HER2-positive breast cancer and trends in use over time. Methods: In the Surveillance, Epidemiology and End Results (SEER) Medicare-linked database we identified women diagnosed with breast cancer from 2010 to 2019. We included those >66 years old who survived 12 months after diagnosis, were enrolled in Medicare Parts A/B for 12 months pre and post-diagnosis, and had local or regional stage HER2-positive cancer. Our primary outcome was receipt of HER2-targeted therapies in the 12 months after diagnosis. Our independent variable was race/ethnicity as measured by the validated Research Triangle Institute race/ethnicity codes in Medicare. Due to small sample sizes, we focus our analysis on White, Black, or Hispanic women. We used multivariable Modified Poisson regression to evaluate changes in the probability of HER2-targeted therapy receipt by race/ethnicity over time, adjusted for sociodemographics, cancer factors, and medical comorbidities. Results: Our cohort comprised 13,887 patients including 8.7% Black, 7.5% Hispanic, and 83.8% White (mean age 74.9). Overall, 7,351 (52.9%) received HER2-targeted therapies in the 12 months post-diagnosis, with use increasing over time in all racial/ethnic groups (Table). Compared with White patients, Black and Hispanic patients had a 19% (adjusted risk ratio [aRR] 0.81, 95% CI:0.69-0.96) and 27% (aRR 0.73, 95% CI 0.61-0.89) lower likelihood, respectively, of receiving HER2-targeted therapies from 2010-2011 (Table). By 2018-2019, no significant differences in receiving HER2-targeted therapies were observed across racial/ethnic groups. Conclusions: In a national cohort of Medicare enrollees with HER2-positive breast cancer, we observed significant racial/ethnic disparities which narrowed over time. Overall utilization rates were low. Future work is needed to understand how improved access to breast cancer treatments impact downstream outcomes. Use of human epidermal growth hormone receptor 2–targeted therapy from 2010-2011 and 2018-2019 by race/ethnicity. Race and Ethnicity Unadjusted Rates Adjusted Risk Ratios (95% CI)* 2010-2011 2018-2019 2010-2011 2018-2019 Black 36% 62% 0.81 (0.69-0.96) 0.97 (0.87-1.08) Hispanic 31% 68% 0.73 (0.61-0.89) 1.01 (0.92-1.12) White 42% 64% Reference Reference *Adjusted for age, marital status, region, breast cancer stage and year of diagnosis, and medical comorbidities.

Roles of Growth Hormone-Dependent JAK-STAT5 and Lyn Kinase Signaling in Determining Lifespan and Cancer Incidence.

In rodents, loss of growth hormone (GH) or its receptor is associated with extended lifespan. We aimed to determine the signaling process resulting in this longevity using GH receptor (GHR)-mutant mice with key signaling pathways deleted and correlate this with cancer incidence and expression of genes associated with longevity. GHR uses both canonical janus kinase (JAK)2-signal transducer and activator of transcription (STAT) signaling as well as signaling via the LYN-ERK1/2 pathway. We used C57BL/6 mice with loss of key receptor tyrosines and truncation resulting in 1) loss of most STAT5 response to GH; 2) total inability to generate STAT5 to GH; 3) loss of Box1 to prevent activation of JAK2 but not LYN kinase; or 4) total knockout of the receptor. For each mutant we analyzed lifespan, histopathology to determine likely cause of death, and hepatic gene and protein expression. The extended lifespan is evident in the Box1-mutant males (retains Lyn activation), which have a median lifespan of 1016 days compared to 890 days for the Ghr-/- males. In the females, GhrBox1-/- mice have a median lifespan of 970 days compared to 911 days for the knockout females. Sexually dimorphic GHR-STAT5 is repressive for longevity, since its removal results in a median lifespan of 1003 days in females compared to 734 days for wild-type females. Numerous transcripts related to insulin sensitivity, oxidative stress response, and mitochondrial function are regulated by GHR-STAT5; however, LYN-responsive genes involve DNA repair, cell cycle control, and anti-inflammatory response. There appears to be a yin-yang relationship between JAK2 and LYN that determines lifespan.

PSI-7 Creation of gene-edited pigs for functional analysis of growth hormone receptor promoters in swine

Abstract Growth hormone (GH; somatotropin) has a central role in animal growth, reproduction, and lactation. The biological actions of GH are dependent on the GH receptor (GHR) that is found in important target tissues such as liver, muscle, adipose tissue, and bone. It is widely accepted that GH is the primary hormone controlling animal growth and that its actions are mediated by the GHR. In humans, laboratory species, and farm animals there are two promoter complexes that control GHR expression. The first promoter complex (P1) controls the liver-specific inducible expression of the GHR1A mRNA. The second promoter complex (P2) controls the non-tissue specific constitutive expression of GHR1B mRNA. Despite the central role that GH and the GHR have in animal growth, the independent function of each promoter complex has not yet been tested in any species. The objective was to perform a germ-line deletion of each GHR promoter complex to test their function in a porcine model. The CRISPR/Cas9 system was used to delete the P1 and P2 promoter complexes in porcine fetal fibroblasts and cloned to create two independent lines for each promoter deletion. Adult animals that were heterozygous (het) for the GHRP1 and GHRP2 deletions were mated to create litters of +/+ (wildtype, WT), +/- (het), and -/- (knockout, KO) pigs for the respective promoters. An RTPCR of liver and muscle confirmed that deletion of GHRP1 and GHRP2 effectively knocked out GHR1A and GHR1B mRNA. Piglets were weighed at birth and approximately monthly until 2 (GHRP1) or 5 (GHRP2) mo of age. Piglets from the GHRP1 line were +/+ (n = 3), +/- (n = 10), and -/- (n = 2) across two litters. Birthweights (1.5 ± 0.1, 1.4 ± 0.1, and 1.5 ± 0.2 kg, respectively) and body weight (BW) at 2 mo of age (32.7 ± 2.9, 27.0 ± 1.6, and 27.0 ± 3.5 kg, respectively) were similar (P > 0.10) for GHRP1 piglets. Piglets from the GHRP2 line were +/+ (n = 2), +/- (n = 6), and -/- (n = 9) across two litters. Birthweights were similar (1.4 ± 0.3, 1.3 ± 0.1, and 1.0 ± 0.1 kg, respectively) but GHRP2-/- pigs weighed less (P < 0.01) at weaning compared with GHRP2+/+ or GHRP2+/- piglets (6.4 ± 0.8, 6.5 ± 0.4, and 4.5 ± 0.4 kg, respectively). Monthly BW for the GHRP2-/- piglets were less (P < 0.001) when compared with GHRP2+/+ or GHRP2+/- piglets. At 5 mo of age, the GHRP2-/- piglets were approximately 50% of the BW of GHRP2+/+ or GHRP2+/- (89.6 ± 6.7, 89.6 ± 3.9, and 43.1 ± 3.2 kg, respectively). In conclusion, the deletion of GHRP2 (and GHR1B mRNA) had a profound effect on pig growth. The GHRP1 deletion (GHR1A mRNA) did not affect growth with the caveat that the GHRP1 litters had not reached maturity. This work was supported by USDA NIFA 2019-67015-29484.

A field study to optimize protein and lipid levels in diet for cage-cultured subadult rockfish Sebastes schlegelii

A feeding trial was conducted to evaluate growth, body composition, serum biochemistry, digestion and metabolism, and oxidation resistence of S. schlegelii fed 9 diets in a 3×3 factorial design (protein levels: 44 %, 48 %, 52 %; lipid levels: 6 %, 10 %, 14 %), to optimize protein and lipid levels for practical feed formula. Rockfish (114.25 g) were stocked into 27 cages in an offshore system and fed test diets to satiation twice daily for 8 weeks. Growth increased but feed conversion rate decreased with dietary protein increasing. Increasing dietary protein to >48 % led to reduced feeding intake but increased protein efficiency ratio. Lipid efficiency ratio increased with dietary protein increasing but decreased with dietary lipid increasing. Hepatosomatic index decreased coupling with the increases in condition factor and liver lipid content as dietary lipid increased to 14 %. Intraperitoneal fat ratio increased with dietary lipid increasing. Increasing dietary protein to > 48 % significantly elevated serum total protein and glucose concentrations, hepatic glycogen synthase activity. High-protein (52 %) diets elevated serum albumin and urea nitrogen concentrations, hepatic pyruvate kinase and alanine aminotransferase (ALT) activities but downregulated hepatic growth-hormone (GH) receptor. Activities of trypsin, lipase, serum superoxide dismutase and total antioxidant capacity decreased with the dietary lipid increasing. Increasing dietary lipid to > 10 % reduced serum GH concentration, and high-lipid (14 %) diets significantly enhanced serum triglyceride concentration and hepatic transaminases activities, and resulted in a visual increase of adipocytes in liver. Serum cholesterol and low-density lipoprotein decreased as dietary protein increased to 48–52 % or dietary lipid >10 %. Hepatic succinate dehydrogenase activity and serum IGF-1 significantly increased while hepatic fatty acid synthetase decreased as dietary protein increased to >48 % or dietary lipid >10 %. High-protein (52 %) diet or high-lipid (14 %) diet elevated serum malonaldehyde concentration. These findings suggested 48 % protein and 10 % lipid were the optimal in diet for subadult S. schlegelii.

Identification of candidate genes and pathways involved in the establishment of sexual size dimorphism in the olive flounder (Paralichthys olivaceus) using RNA-seq

Olive flounder (Paralichthys olivaceus) is a valuable mariculture fish that shows female-biased sexual size dimorphism (SSD), yet the molecular mechanisms responsible for this phenomenon remain poorly understood. In this study, the growth differences between females and males were compared, and comparative transcriptome analyses of brains/pituitaries, livers, muscles, and gonads from 13-month-old females and males were performed. The critical time window for SSD was from 13- to 14-month-old, with females reaching significantly larger sizes than males. Muscle cell size and plasma growth hormone (GH), insulin-like growth factor 1 and 2 (IGF1, IGF2), 11-ketotestosterone (11-KT), and 17β-estradiol (E2) levels had no significant differences between the sexes of 13- and 14-month-old flounders. Furthermore, the RNA-seq data revealed differential expression in the genes encoding the receptors for these hormones, suggesting that regulation may occur at the receptor level, potentially leading to SSD during the critical window. RNA-seq analysis identified 88, 645, 414, and 15,833 differentially expressed genes between females and males in brains/pituitaries, livers, muscles, and gonads, respectively. KEGG (Kyoto Encyclopedia of Genes and Genomes) and GSEA-based KEGG analyses revealed that some pathways associated with growth and development, including “prolactin signaling pathway” in brains/pituitaries, “cell cycle”, “oocyte meiosis”, and “DNA replication” in livers, “focal adhesion”, “ECM-receptor interaction”, “protein digestion and absorption”, “arginine and proline metabolism”, and “cysteine and methionine metabolism” in muscles, and “Hippo signaling pathway” and “JAK-STAT signaling pathway” in gonads may be involved in the establishment of sexual growth differences. Notably, females had lower steroid hormone synthesis abilities than males in brains/pituitaries, livers, and gonads, indicating the importance of sex steroid hormones in the establishment of SSD. Moreover, genes including frizzled3 (fzd3) and prolactin (prl) in brains/pituitaries, and growth hormone receptor (ghr), estrogen receptor (esr1), insulin-like growth factor binding protein-3 (igfbp3), bone morphogenetic protein 8A-like (bmp8a), leptin receptor (lepr), and lipoprotein lipase-like (lpl) in livers emerge as potential candidates for the establishment of SSD. In conclusion, this study may help clarify the molecular mechanisms involved in SSD-related growth traits in flounder and provide basic data for genetic breeding of flounder.

Association of alcohol with lung cancer risk in men with different growth hormone receptor genotypes

ObjectiveTo test whether genetic variants of the growth hormone receptor gene (GHR) modulate the effect of lifestyle variables on lung cancer (LC) risk. Materials and methodsThis population-based cohort study involved 6,439 men from the Japan-Hawaii Cancer study drawn from the Kuakini Honolulu Heart Program who were cancer-free at baseline examination (1965–1968; age 45–68 years) and followed-up until December 1999. We determined the association of GHR SNP rs4130113 genotypes GHR-AA (common allele A homozygotes) and GHR-G (minor allele G carriage) with alcohol drinking, BMI, physical activity and cigarette smoking in relation to LC and non-small cell LC (NSCLC). Results were expressed as hazard ratios and 95 % CIs estimated from Cox proportional hazard models. ResultsOver mean 26.7 ± 7.4 SD years follow-up, 190 LC cases, including 133 NSCLC cases, were diagnosed. After adjusting for age, education, alcohol intake, BMI, physical activity, cigarette smoking, green tea consumption and dietary saturated fat, main-effect Cox models showed that compared with GHR-AA, GHR-G was associated with protection against LC: HR = 0.75 (95 % CI, 0.56–1.00). Full Cox models showed GHR-G interacted with alcohol intake only (β = 1.171; p = 0.0003; drinks per week: β = 0.279; P = 0.0025). Stratified analyses showed that for GHR-AA, drinkers had reduced LC risk (HR = 0.53; 95 % CI, 0.34–0.84), and that <2 drinks/week had the strongest protection (HR = 0.39; 95 % CI, 0.18–0.84). In contrast, for GHR-G, alcohol drinkers had increased LC risk (HR = 1.74; 95 % CI, 1.11–2.75) which was dose-dependent (P for trend = 0.003). Results for NSCLC were similar. ConclusionIn men with the GHR-AA genotype, alcohol drinking at a low dose poses significantly less risk of LC compared with non-drinkers and higher alcohol consumption., the overall relationship being U-shaped. In contrast, in GHR minor allele carriers, alcohol posed a progressively greater risk of LC as amount consumed increased