Higher IGF-I Levels Research Articles

Diagnosis of Chromosome 15q-Terminal Deletion Syndrome through Elevated Fasting Serum Growth Hormone Levels

Chromosome 15q26-qter deletion syndrome is a rare disease that causes prenatal and postnatal growth retardation, microcephaly, developmental delay, and congenital heart diseases, mainly due to haploinsufficiency of IGF1R. In addition, patients with pathogenic variants of the IGF1R show similar symptoms. We report the case of a 5-month-old girl with prenatal and postnatal growth retardation, microcephaly, and congenital heart disease. At 5 months of age, her length was 54.7 cm (−4.3 SD), her weight was 4.4 kg (−3.1 SD), and her head circumference was 37.4 cm (−2.8 SD), thus presenting severe growth retardation. Repeated pre-feeding serum GH levels were abnormally high (26.1–85.5 ng/mL), and IGF-1 levels (+0.16 to +1.2 SD) were relatively high. The 15q sub-telomere fluorescence in situ hybridization analysis revealed a heterozygous deletion in the 15q terminal region. Whole-genome single nucleotide polymorphism microarray analysis showed a terminal deletion of 6.4 Mb on 15q26.2q26.3. This is the first report showing that fasting GH levels are high in early infancy in patients with IGF1R abnormalities. In addition to relatively high IGF-1 levels, elevated fasting GH levels in early infancy may contribute to the diagnosis of IGF1R abnormalities.

Various phenotypes of short stature with heterozygous IGF-1 receptor (IGF1R) mutations.

.Type 1 insulin-like growth factor receptor (IGF1R) plays an important role in normal fetal and postnatal growth. Over 30 pathogenic variants of IGF1R have been identified in patients with short stature. Yet, 20 years after the first report, a variety of phenotypes remain poorly defined. We analyzed the genetic and clinical data and responses to GH therapy in 11 patients using results from questionnaires. Eight of the 11 patients have already been reported in previous articles, and all of the identified mutations were heterozygous. The patients exhibited various phenotypes. At least two patients did not meet the criteria for GH treatment for small for gestational age (SGA) short stature, and two more patients showed lower serum IGF1 levels. Nine of the 11 patients had thin upper lips. Five patients with heterozygous IGF1R treated with GH exhibited similar height gains to those reported in previous Japanese studies on SGA short stature, which also led to extremely high serum IGF1 levels. Patients with short stature due to IGF1R mutations exhibit various phenotypes. Their presentation at diagnosis may be indistinguishable from common short stature. More specific clinical scoring that considers elevated IGF1 levels after GH treatment is needed to better detect IGF1R mutations.

ВЛИЯНИЕ ГРУДНОГО ВСКАРМЛИВАНИЯ НА АНТРОПОМЕТРИЧЕСКИЕ ПОКАЗАТЕЛИ И ГОРМОНАЛЬНЫЙ СТАТУС КРУПНОВЕСНЫХ И МАЛОВЕСНЫХ ДЕТЕЙ В ДИНАМИКЕ ПЕРВЫХ ДВУХ ЛЕТ ЖИЗНИ

The most important regulators of the rate of growth and physical development in children are rational nutrition and hormones. The aim is to evaluate the effect of breastfeeding on the anthropometric parameters and hormonal profile of large and small for gestational age children in the dynamics of the first two years of life. 280 full-term newborns were examined with dynamic follow-up during 2 years of life. The main group 1 (Gr1) ‒ 110 large for gestational age, Gr2 ‒ 95 small for gestational age, the control group ‒ 72 with indicators corresponding to the gestational age. The dynamics of anthropometric indicators, the nature of feeding, nutritional and hormonal status were analyzed, taking into account body weight at birth. It has been established that infants with low birth weight during the first year of life are significantly less likely to receive exclusively breast milk. The proportion of children who received exclusive breastfeeding in the neonatal period is lower than in the control group (p=0.002). Correlations between the duration of breastfeeding and indicators of physical development and adipokines status in newborns and young children have been established. Three-month-old low birth weight infants treated with breast milk substitutes showed a higher level of IGF-1 (p=0.047) and a lower concentration of adiponectin (p=0.045) in blood serum. In large for gestational age infants, a higher content of IGF-1 (p=0.029) and insulin (p=0.015) was established. The revealed features of anthropometric and hormonal status substantiate the importance of providing conditions for long-term breastfeeding, continuity in the provision of medical care to small and large for gestational age babies, and educational work with parents.

Outcomes Based on Plasma Biomarkers for the Phase 3 CELESTIAL Trial of Cabozantinib versus Placebo in Advanced Hepatocellular Carcinoma

Introduction: Cabozantinib, an inhibitor of MET, AXL, and VEGF receptors, significantly improved overall survival (OS) and progression-free survival (PFS) versus placebo in patients with previously treated advanced hepatocellular carcinoma (HCC). In this exploratory analysis, outcomes were evaluated according to plasma biomarker levels. Methods: Baseline plasma levels were evaluated for MET, AXL, VEGFR2, HGF, GAS6, VEGF-A, PlGF, IL-8, EPO, ANG2, IGF-1, VEGF-C, and c-KIT for 674/707 randomized patients; and Week 4 levels were evaluated for MET, AXL, VEGFR2, HGF, GAS6, VEGF-A, PlGF, IL-8, and EPO for 614 patients. OS and PFS were analyzed by baseline levels as dichotomized or continuous variables and by on-treatment changes at Week 4 as continuous variables; biomarkers were considered potentially prognostic if p < 0.05 and predictive if p < 0.05 for the interaction between treatment and the biomarker. Multivariable analyses adjusting for clinical covariates were also performed. Results: In the placebo group, high levels of MET, HGF, GAS6, IL-8, and ANG2 and low levels of IGF-1 were associated with shorter OS in univariate and multivariable analyses; these associations were also observed for MET, IL-8, and ANG2 in the cabozantinib group. Hazard ratios for OS and PFS favored cabozantinib over the placebo at low and high baseline levels for all biomarkers. No baseline biomarkers were predictive of a treatment benefit. Cabozantinib promoted pharmacodynamic changes in several biomarkers, including increases in VEGF-A, PlGF, AXL, and GAS6 levels and decreases in VEGFR2 and HGF levels; these changes were not associated with OS or PFS. Conclusion: Cabozantinib improved OS and PFS versus placebo at high and low baseline concentrations for all biomarkers analyzed. Low baseline levels of MET, HGF, GAS6, IL-8, and ANG2 and high levels of IGF-1 were identified as potential favorable prognostic biomarkers for survival in previously treated advanced HCC. Although cabozantinib promoted pharmacodynamic changes in several biomarkers, these changes were not associated with survival.

ADVANCES IN THE NEUROSURGICAL AND COMBINED TREATMENT OF PATIENTS WITH ACROMEGALY

Aim. The study was carried out to identify and analyze the factors of a positive outcome of surgical and radiation treatment of acromegaly. Methods. The work was performed on clinical material and summarizes treatment results of 256 patients (90 males and 166 females). 86% of patients underwent surgical treatment, 14% of patients received radiation therapy during 2002–2018. Significance of factors of a positive outcome of treatment was carried out using the RStudio program. Results. The results of the study revealed that: 1. Significant factors (p &lt;0.05) of a positive outcome of surgical treatment of acromegaly are somatostatin analogs (SSA) therapy before surgery, a small tumor size (microadenomas), and the absence of extrasellar tumor spread. 2. The most significant factor in achieving remission of acromegaly after non-radical adenomectomy is postoperative therapy with SSA (p &lt;0.05). 3. Aggressive pituitary tumors invading surrounding structures, high baseline IGF-1 levels, unfavorable histological findings, macroadenomas, growth hormone levels above 10 μg/L before therapy, and extrasellar tumor spread were associated with less favorable outcomes of acromegaly radiation therapy (RT) (p &lt;0.05). The most significant factor in achieving remission of acromegaly is SSA therapy after RT (p &lt;0.05). Conclusion. Surgical treatment is the optimal primary treatment for acromegaly. Drug therapy with SSA is effective and the preferred treatment after non-radical surgery.

Extreme insulin resistance during pregnancy: a therapeutic challenge.

SummaryDuring pregnancy, maternal tissues become increasingly insensitive to insulin in order to liberate nutritional supply to the growing fetus, but occasionally insulin resistance in pregnancy becomes severe and the treatment challenging. We report a rare and clinically difficult case of extreme insulin resistance with daily insulin requirements of 1420 IU/day during pregnancy in an obese 36-year-old woman with type 2 diabetes (T2D) and polycystic ovary syndrome (PCOS). The woman was referred to the outpatient clinic at gestational week 12 + 2 with a hemoglobin A1c (HbA1c) at 59 mmol/mol. Insulin treatment was initiated immediately using Novomix 30, and the doses were progressively increased, peaking at 1420 units/day at week 34 + 4. At week 35 + 0, there was an abrupt fall in insulin requirements, but with no signs of placental insufficiency. At week 36 + 1 a, healthy baby with no hypoglycemia was delivered by cesarean section. Blood samples were taken late in pregnancy to search for causes of extreme insulin resistance and showed high levels of C-peptide, proinsulin, insulin-like growth factor (IGF-1), mannan-binding-lectin (MBL) and leptin. CRP was mildly elevated, but otherwise, levels of inflammatory markers were normal. Insulin antibodies were undetectable, and no mutations in the insulin receptor (INSR) gene were found. The explanation for the severe insulin resistance, in this case, can be ascribed to PCOS, obesity, profound weight gain, hyperleptinemia and inactivity. This is the first case of extreme insulin resistance during pregnancy, with insulin requirements close to 1500 IU/day with a successful outcome, illustrating the importance of a close interdisciplinary collaboration between patient, obstetricians and endocrinologists.Learning pointsThis is the first case of extreme insulin resistance during pregnancy, with insulin requirements of up to 1420 IU/day with a successful outcome without significant fetal macrosomia and hypoglycemia.Obesity, PCOS, T2D and high levels of leptin and IGF-1 are predictors of severe insulin resistance in pregnancy.A close collaboration between patient, obstetricians and endocrinologists is crucial for tailoring the best possible treatment for pregnant women with diabetes, beneficial for both the mother and her child.

The Effect of the GH/IGF-1 Axis During Trypanosoma Cruzi Infection

Trypanosoma cruzi is the parasite responsible for Chagas disease (CD), that affects 6-8 million people worldwide. CD treatment is limited to two drugs (benznidazole and nifurtimox). Treatment is mostly effective during the acute phase of the disease (initial two months post-infection), while their efficacy during the chronic phase is controversial. In the absence of treatment, 30% of infected individuals suffer irreversible chronic cardiac and digestive damages, which lead to inability and, in some instances, death. Patients with Laron Syndrome (LS, a form of congenital GH insensitivity) are short in stature with low levels of IGF-1, elevated levels of GH and, surprisingly, are resistant to cancer and diabetes. A cohort of LS patients living in southern Ecuador, where CD is endemic, has been studied by Dr. Jaime Guevara for over 25 years (1). Few, if any, cases of CD have been reported among these patients (Dr. Guevara, personal communications). T. cruzi infection has been shown to directly modulate pituitary hormones such as GH, PRL and glucocorticoids (stress related hormones), leading to immunosuppression and thymic atrophy by depletion of CD4+ CD8+ cells. Previously, rats infected with T. cruzi and treated with GH showed reduced parasitism and less tissue damage compared to controls (2). The purpose of this research is to investigate the in vitro effect of GH during T. cruzi infection, simulating conditions of GH insensitivity. First, we separately treated T. cruzi and the host cells [human cervical cancer cell line (HeLa) and male mouse fibroblast (L-cells)] with relatively low or high levels of GH, IGF-1, PRL, and EGF. Next, we treated the parasite and host cells simultaneously with these hormones. When the parasites were treated alone, T. cruzi responded to exogenous GH (5ng/ml-50ng/ml) by significantly increasing the percentage of amastigotes (less infective form of the parasite). Also, when GH (50ng/ml) were administered to the host cells, T. cruzi infectivity was significantly reduced by 12% (percentage of infection) compared to 20% from untreated conditions. Similarly, both parasite and host cells treated with GH significantly reduced T. cruzi infectivity (10%) compared to untreated conditions (18%). We further treated both cell lines with a combination of GH/IGF-1. Conditions used were as follows: control (no-treatment), moderate levels (5ng/ml GH+150 ng/ml IGF-1), relatively high levels (50ng/ml GH+600ng/ml IGF-1), or levels that would simulate those found in patients with LS(50ng/ml GH+20 ng/ml IGF-1). Of these, the LS concentrations significantly reduced infection in both cell lines (11%) compared to control (16%). Together these results indicate that GH can influence T. cruzi infectivity and that GH, not IGF-1, is mediating the decreased infectivity. Finally, the results suggest that high concentrations of GH, as seen in LS patients, could be protective during T. cruzi infection.1)Guevara-Aguirre et al., 2011 2) Frare et al., 2010

Titrating Growth Hormone Dose to High-Normal IGF-1 Levels Has Beneficial Effects on Body Fat Distribution and Microcirculatory Function Despite Causing Insulin Resistance.

To clarify the mechanism underlying the described U-shaped relation of both low and high levels of IGF-1 with cardiovascular disease this study explores the effect of decreasing and increasing growth hormone dose in GH deficient adults on (micro)vascular function, body composition and insulin resistance. In this randomized clinical trial, thirty-two subjects receiving GH therapy with an IGF-1 concentration between −1 and 1 SD score (SDS) for at least one year were randomized to receive either a decrease (IGF-1 target level of −2 to −1 SDS) or an increase of their daily GH dose (IGF-1 target level of 1 to 2 SDS) for a period of 24 weeks. Microvascular endothelium (in)dependent vasodilatation and vasomotion, vascular stiffness by pulse wave analysis, and HOMA-IR were measured. At the end of the study 30 subjects (65.6% men, mean age 46.6 (SD 9.9) years) were analyzed. There was a favorable effect of increasing the IGF-1 level on waist circumference compared to decreasing the IGF-1 level (p=0.05), but a detrimental effect on insulin resistance (p=0.03). Decreasing IGF-1 level significantly lowered the endothelial domain of vasomotion (p=0.03), whereas increasing IGF-1 level increased the contribution of the neurogenic domain (p=0.05). This change was related to the favorable change in waist circumference. In conclusion, increasing IGF-1 levels was beneficial for body composition but detrimental with respect to insulin resistance. The contribution of the neurogenic vasomotion domain increased in parallel, and could be explained by the favorable change in waist circumference.Clinical Trial RegistrationClinicalTrials.gov, identifier NCT01877512.

Cognitive profiles and brain volume are affected in patients with Silver–Russell syndrome

Silver–Russell syndrome (SRS) is a rare condition associated with pre and postnatal growth retardation. The most common causes of SRS are 11p15 ICR1 loss of methylation (LOM) and maternal uniparental disomy of chromosome 7 (mUPD7). Almost all patients with SRS have a history of intrauterine growth retardation (IUGR) and may be born small for gestational age (SGA). Children with SRS show typical features, including relative macrocephaly, prominent forehead, body asymmetry, feeding difficulties and cognitive delay (1)(2). SRS patients with 11p15 LOM show high IGF1 levels suggestive of IGF1 insensitivity. IGF1 is implicated in brain development, in particular with neural proliferation and cognitive function (2)(3).

The prevalence of silent acromegaly in prolactinomas is very low.

The aim of this study was to evaluate the somatotroph axis in a large series of patients with prolactinoma to verify the prevalence of silent acromegaly in this population. A hundred and forty-four patients were enrolled in a multicenter study: 90 were already on cabergoline (CAB) and enrolled in a cross-sectional arm (group A) with random PRL, GH and IGF-I determination on treatment (≥3months), whereas 54 untreated patients were enrolled at diagnosis in a prospective arm (group B) with PRL, GH and IGF-I measurement before and after 6 and 12months of treatment. In the presence of high IGF-I, CAB was withdrawn for 3months and GH, IGF-I, PRL and GH during an oral Glucose Tolerance Test (OGTT) were obtained. High IGF-I levels (ULN 1.01-1.56) were observed in 9 patients (6.25%, 5F). After CAB withdrawal, IGF-I levels normalized in 5/9 patients, GH was<0.4ng/ml after OGTT in 7/9 cases or at random GH determination in one case. After CAB re-introduction, IGF-I levels re-increased in a single case. Overall, a single young female patient harboring a macroadenoma in group A was diagnosed with silent acromegaly and underwent successful transsphenoidal removal of a GH/PRL-secreting adenoma. The prevalence of silent acromegaly in prolactinomas (0.7%) is lower than previously reported and OGTT is helpful to recognize silent acromegaly. We suggest that the somatotroph axis should be evaluated at diagnosis in all cases and not systematically during follow-up.

Insulin-like Growth Factor-1 and IGF Binding Proteins Predict All-Cause Mortality and Morbidity in Older Adults.

While the growth hormone/insulin-like growth factor-1 (GH/IGF-1) pathway plays essential roles in growth and development, diminished signaling via this pathway in model organisms extends lifespan and health-span. In humans, circulating IGF-1 and IGF-binding proteins 3 and 1 (IGFBP-3 and 1), surrogate measures of GH/IGF-1 system activity, have not been consistently associated with morbidity and mortality. In a prospective cohort of independently-living older adults (n = 840, mean age 76.1 ± 6.8 years, 54.5% female, median follow-up 6.9 years), we evaluated the age- and sex-adjusted hazards for all-cause mortality and incident age-related diseases, including cardiovascular disease, diabetes, cancer, and multiple-domain cognitive impairment (MDCI), as predicted by baseline total serum IGF-1, IGF-1/IGFBP-3 molar ratio, IGFBP-3, and IGFBP-1 levels. All-cause mortality was positively associated with IGF-1/IGFBP-3 molar ratio (HR 1.28, 95% CI 1.05–1.57) and negatively with IGFBP-3 (HR 0.82, 95% CI 0.680–0.998). High serum IGF-1 predicted greater risk for MDCI (HR 1.56, 95% CI 1.08–2.26) and composite incident morbidity (HR 1.242, 95% CI 1.004–1.538), whereas high IGFBP-1 predicted lower risk for diabetes (HR 0.50, 95% CI 0.29–0.88). In conclusion, higher IGF-1 levels and bioavailability predicted mortality and morbidity risk, supporting the hypothesis that diminished GH/IGF-1 signaling may contribute to human longevity and health-span.

The Prognostic Significance of IGF-1R and the Predictive Risk Value of Circulating IGF-1 in Tunisian Patients with Laryngeal Carcinoma

The aim was to evaluate the clinical impact of IGF-1/IGF-1R in Tunisian laryngeal carcinoma. A high IGF-1R immunohistochemical expression was found in our series (81.43%). A tendency toward an association between IGF-1R expression and lymph node metastasis was found (p = 0.068). Patients with positive IGF-1R expression showed a short disease free survival (p = 0.053) and a high recurrence rate. Furthermore, circulating IGF-1 levels sera, detected by ELISA, were higher among patients compared to controls (p < 0.001). IGF-1R might have a prognostic significance and could be a factor of tumor recurrence. However, high levels of IGF-1 increase the risk of developing of LSCC disease.

Pharmacological Strategies for Insulin Sensitivity in Obesity and Cancer: Thiazolidinediones and Metformin.

Chronic diseases, such as obesity and cancer, have high prevalence rates. Both diseases have hyperinsulinemia, hyperglycemia, high levels of IGF-1 and inflammatory cytokines in common. Therefore, these can be considered triggers for cancer development and growth. In addition, low-grade inflammation that modulates the activation of immune cells, cellular metabolism, and production of cytokines and chemokines are common in obesity, cancer, and insulin resistance. Pharmacological strategies are necessary when a change in lifestyle does not improve glycemic homeostasis. In this regard, thiazolidinediones (TZD) possess multiple molecular targets and regulate PPARγ in obesity and cancer related to insulin resistance, while metformin acts through the AMPK pathway. The aim of this study was to review TZD and metformin as pharmacological treatments for insulin resistance associated with obesity and cancer. Thiazolidinediones restored adiponectin secretion and leptin sensitivity, reduced lipid droplets in hepatocytes and orexigen peptides in the hypothalamus. In cancer cells, TZD reduced proliferation, production of reactive oxygen species, and inflammation by acting through the mTOR and NFκB pathways. Metformin has similar effects, though these are AMPK-dependent. In addition, both drugs can be efficient against certain side effects caused by chemotherapy.

Osteoclast-derived IGF1 is required for pagetic lesion formation in vivo.

We report that transgenic mice expressing measles virus nucleocapsid protein (MVNP) in osteoclasts (OCLs) (MVNP mice) are Paget's disease (PD) models and that OCLs from patients with PD and MVNP mice express high levels of OCL-derived IGF1 (OCL-IGF1). To determine OCL-IGF1's role in PD and normal bone remodeling, we generated WT and MVNP mice with targeted deletion of Igf1 in OCLs (Igf1-cKO) and MVNP/Igf1-cKO mice, and we assessed OCL-IGF1's effects on bone mass, bone formation rate, EphB2/EphB4 expression on OCLs and osteoblasts (OBs), and pagetic bone lesions (PDLs). A total of 40% of MVNP mice, but no MVNP/Igf1-cKO mice, had PDLs. Bone volume/tissue volume (BV/TV) was decreased by 60% in lumbar vertebrae and femurs of MVNP/Igf1-cKO versus MVNP mice with PDLs and by 45% versus all MVNP mice tested. Bone formation rates were decreased 50% in Igf1-cKO and MVNP/Igf1-cKO mice versus WT and MVNP mice. MVNP mice had increased EphB2 and EphB4 levels in OCLs/OBs versus WT and MVNP/Igf1-cKO, with none detectable in OCLs/OBs of Igf1-cKO mice. Mechanistically, IL-6 induced the increased OCL-IGF1 in MVNP mice. These results suggest that high OCL-IGF1 levels increase bone formation and PDLs in PD by enhancing EphB2/EphB4 expression in vivo and suggest OCL-IGF1 may contribute to normal bone remodeling.

The relationship between cortisol and IGF-I influences metabolic alteration in pediatric overweight and obesity.

Data on metabolic impairments in Cushing's syndrome and GH deficiency all suggest that the relationship between cortisol and GH/IGF-I axis in obesity may have a role in the related diseases. However, studies focusing only on one of these hormones are often controversial in paediatrics. We aimed to explore the simultaneous relationship between cortisol and IGF-I with the metabolic alterations in paediatric obesity. Retrospective cross-sectional study in a tertiary care center. We recruited 876 (441 males and 435 females) overweight and obese children and adolescents. A complete clinical and biochemical evaluation including OGTT was performed. Cortisol and IGF-I SDS were divided in quartiles and then crossed to explore the reciprocal influence of high/high, low/low, and high/low levels of each one on the metabolic alterations of obesity. Subjects in the higher quartiles of IGF-I-SDS and cortisol had an increased risk of hypertension, hypercholesterolemia, high levels of triglycerides, and reduced HDL cholesterol. Diversely, lower IGF-I-SDS quartiles were associated with higher blood glucose, insulin, insulin resistance, and reduced insulin sensitivity levels with the rise of cortisol quartiles. We observed that apart from glucose metabolism that is associated with low IGF-I and high cortisol levels, the other parameters known to be associated with increased cardiovascular risk were related to high levels of both IGF-I and cortisol, even if within normal range. Cortisol and IGF-I play a complex role in the comorbidities of obesity, and the evaluation of both variables could clarify some of the discordant results.

Randomized, double-blind, placebo-controlled phase II study of istiratumab (MM-141) plus nab-paclitaxel and gemcitabine versus nab-paclitaxel and gemcitabine in front-line metastatic pancreatic cancer (CARRIE)

Preclinical data suggest that dual blockade of the insulin-like growth factor-1 receptor (IGF-1R) and HER3 pathways has superior activity to IGF-1R blockade alone in pancreatic ductal adenocarcinoma (PDAC). We tested whether istiratumab, an IGF-1R- and ErbB3-bispecific antibody, can enhance the efficacy of standard of care (SOC) chemotherapy in patients with metastatic PDAC selected for high IGF-1 serum levels. CARRIE was an international, randomized, double-blind, placebo-controlled phase II study for patients with previously untreated metastatic PDAC. In part 1, 10 patients were evaluated for pharmacokinetics and safety. In part 2, patients with high free serum IGF-1 levels were randomized 1 : 1 to receive either istiratumab [2.8g intravenously (i.v.) every 2 weeks] or placebo combined with gemcitabine/nab-paclitaxel at approved dose schedule. The co-primary endpoints were progression-free survival (PFS) in patients with high IGF-1 levels and PFS in patients with both high serum IGF-1 levels and heregulin (HRG)+ tumors. Key secondary endpoints were overall survival (OS), objective response rate (ORR) by RECIST v.1.1, and adverse events (AEs) rate. A total of 317 patients were screened, with 88 patients randomized in part 2 (experimental arm n= 43; control n= 45). In the high IGF-1 cohort, median PFS was 3.6 and 7.3 months in the experimental versus control arms, respectively [hazard ratio (HR)= 1.88, P= 0.027]. In the high IGF-1/HRG+ subgroup (n= 44), median PFS was 4.1 and 7.3 months, respectively (HR= 1.39, P= 0.42). Median OS and ORR for the overall population were similar between two arms. No significant difference in serious or grade ≥3 AEs was observed, although low-grade AEs leading to early discontinuation were higher in the experimental (39.5%) versus control arm (24.4%). Istiratumab failed to improve the efficacy of SOC chemotherapy in this patient setting. High serum IGF-1 levels did not appear to be an adverse prognostic factor when compared with non-biomarker-selected historic controls. ClinicalTrials.gov: NCT02399137; EUDRA CT: 2014-004572-34.

Targeted Searches of the Electronic Health Record and Genomics Identify an Etiology in Three Patients with Short Stature and High IGF-I Levels

Introduction: Short stature is one of the most common reasons for referral to a pediatric endocrinologist and can result from many etiologies. However, many patients with short stature do not receive a definitive diagnosis. Objective: To ascertain whether integrating targeted bioinformatics searches of electronic health records (EHRs) combined with genomic studies could identify patients with previously undiagnosed rare genetic etiologies of short stature. We focused on a specific rare phenotypic subgroup: patients with short stature and elevated IGF-I levels. Methods: We performed a cross-sectional cohort study at three large academic pediatric healthcare networks. Eligible subjects included children with heights below –2 SD, IGF-I levels >90th percentile, and no known etiology for short stature. We performed a search of the EHRs to identify eligible patients. Patients were then recruited for phenotyping followed by exome sequencing and in vitro assays of IGF1R function. Results: A total of 234 patients were identified by the bioinformatics algorithm with 39 deemed eligible after manual review (17%). Of those, 9 were successfully recruited. A genetic etiology was identified in 3 of the 9 patients including 2 novel variants in IGF1R and a de novo variant in CHD2. In vitro studies supported the pathogenicity of the IGF1R variants. Conclusions: This study provides proof of principle that patients with rare phenotypic subgroups can be identified based on discrete data elements in the EHRs. Although limitations exist to fully automating this approach, these searches may help find patients with previously unidentified rare genetic disorders.

Associations between serum levels of insulin-like growth factor-I and bone mineral acquisition in pubertal children: a 3-year follow-up study in Hamamatsu, Japan

BackgroundEpidemiological data regarding the association between serum levels of IGF-I and bone mineral acquisition during childhood are scarce. Here, we investigated the association between serum levels of IGF-I and bone status during puberty.MethodsWe analyzed prospective 3-year follow-up data of 254 community-dwelling children who completed both baselines (at age 11.2 years) and follow-up (at age 14.2 years) surveys in Hamamatsu, Japan. Total body (TB) bone area and bone mineral parameters were assessed using dual-energy X-ray absorptiometry.ResultsDuring the 3-year follow-up period, there were significant (P < 0.05) increases in total body less head (TBLH) areal bone mineral density (aBMD), TBLH bone mineral content (BMC), and TB bone area, and a significant decrease in TB bone mineral apparent density (BMAD, volumetric bone mineral density, vBMD). IGF-I levels showed significant positive relationships with TBLH BMC and TBLH aBMD at both baseline and follow-up. TBLH aBMD in boys and TB BMAD in girls at follow-up showed significant increases from the lowest to highest quartiles of baseline IGF-I levels after adjusting for confounding factors. Similarly, changes in TBLH aBMD in boys and TB BMAD in girls during the 3-year follow-up period showed significant increases from the lowest to highest quartiles of baseline IGF-I levels after adjusting for confounding factors.ConclusionsThese results suggest that pubertal children with high levels of serum IGF-I tended to have high bone mineral acquisition later on.

Transcriptional and Spatial Heterogeneity of Mouse Megakaryocytes at Single-Cell Resolution

Megakaryocytes (MKs) have long been described solely as platelet progenitors. However, recent studies show that MKs also act as an essential component of the bone marrow niche to maintain hematopoietic stem cell function, and combat infection by engulfing and presenting antigens. However, it is not known whether these diverse programs are executed by a single cell population or distinct subsets of cells. We performed single-cell RNA sequencing (scRNA-seq) to dissect the heterogeneity of MKs. To overcome the difficulty in obtaining the rare (0.1% in BM) and oversized (up to 65μm) highly polyploid, fragile MKs, we developed an efficient isolation strategy by combining fluorescence-activated cell sorting (FACS) sorting, manual selection of highly viable cells, and FISH verification of ploidy. We obtained 920 CD41+ highly-purified, bone-marrow derived, murine MKs spanning each ploidy stages (2N-32N) for scRNA-seq with modified Smart-seq2 protocol. On average, we detected over 6800 expressed genes and 250,000 transcripts in each MK. All cells expressed classical markers such as Pf4 and Itga2b (CD41). Four cell clusters were identified using an unsupervised clustering method. Cells in Cluster 1 expressed mature MK markers CD42 and CD61, were enriched for hemostasis and platelet activation expression signatures, and consist of ≥8N cells, suggesting these MKs may represent platelet generating MKs. Cells in cluster 2 had lower CD42 and CD61 expression, were low ploidy (≤8N), and had higher expression of inflammation-related genes, including Ctss and Itgam ("inflammatory response-associated MKs"). Cells in Cluster 3 were enriched for DNA replication and DNA strand elongation (GO terms) and were in all ploidy stages ("MKs in polyploidization stage"). Cluster 4, most of which were high-ploidy, expressed high levels of CD42, CD61, TGF-β, and IGF1: factors regulating HSC behavior ("HSC niche cells"). Furthermore, we identified cell population-specific surface markers and transcription factors (TFs) for each of the 4 clusters. Then, immunostaining using antibodies against corresponding markers were performed to confirm the presence of respective MK subpopulations in the bone marrow. Our analyses suggest that defining MK stages by ploidy and traditional markers CD42 and CD61 alone may result in a genetically and developmentally heterogenous population of MK. Rather, MKs at various stages may be more specifically identified by these gene signatures. MKs with different functions are known to have specific spatial distribution in the bone marrow (BM) niche. To test whether MKs with distinct expression signatures are uniquely localized within BM, we performed immunofluorescence staining on BM sections using antibodies against cell population-specific marker genes. Remarkably, we observed that Cluster 1 cells directly contacted blood vessels while most of Cluster 4 cells resided within one cell diameter of HSCs. The unique spatial distribution of cluster 1 and 4 population are in consistency with their respective transcriptomic signatures, and support that platelet generation and HSC maintenance are carried out by two distinct MK subpopulations. We further investigated the potential intrinsic relationship of these four Clusters during megakaryopoiesis. Developmental time courses were reconstructed using Monocle analysis, demonstrating that polyploidization (Cluster 3) occurs at the early stage of MK development with subsequent differentiation toward three orientations. While MKs with low ploidy appear to have two distinct cell fates (immuno-modulation or polyploidization), MKs with high ploidy (≥8N) differentiate towards populations associated with platelet production or stem cell regulation. In summary, our study provides the first in vivo transcriptomic profile of megakaryopoiesis and a potential map of megakaryocyte heterogeneity at the single-cell resolution. MKs may be classified into different functional subpopulations irrespective to their developmental stage and degree of ploidy. These observations suggest that megakaryopoiesis does not occur merely in a stepwise process, but is dynamic and adaptive to locations in the BM and biological needs. Disclosures No relevant conflicts of interest to declare.

Abstract 874: The CRTC1/MAML2 oncogene induces a PGC-1a splice variant that sensitizes mucoepidermoid carcinoma cells to PPARg inhibition

Abstract Mucoepidermoid carcinoma (MEC) is the most common type of malignant salivary gland tumor. MECs frequently exhibit a recurrent t(11;19)(q21;p13) chromosomal translocation that fuses the transcriptional coactivators CRTC1 (CREB-Regulated Transcription Coactivator 1; C1) and MAML2 (Mastermind-Like 2; M2). Though many C1/M2-positive tumors are easily resected, some do progress to advanced, metastatic disease accompanied by poor 5-year survival rates. Thus, it is critical to understand the mechanisms by which C1/M2 drives tumor growth and progression in order to identify therapeutic vulnerabilities. Our lab recently identified a correlation between C1/M2 expression and increased levels of the growth hormone IGF-1. This hormone plays critical roles in the development and homeostasis of normal salivary glands, and its dysregulation has been implicated in several cancers including colon and lung cancers. Interestingly, we demonstrate that IGF-1 is not directly upregulated by C1/M2. Rather, we have discovered a novel C1/M2-driven signaling circuit whereby constitutive CREB activation drives the increased production of a minor PGC-1α (PPARγ Coactivator 1α) splice variant, PGC-1α4, which is responsible for the high IGF-1 levels observed in C1/M2-positive MEC cells. Notably, the PGC-1α4 splice variant is minimally expressed in normal tissues and C1/M2-negative cell lines but is selectively upregulated in C1/M2-positive cell lines. We show that C1/M2 directly binds CREB at the PGC-1α4 promoter to induce expression of this variant, resulting in increased IGF-1 expression. IGF-1 promoter analysis revealed a significant enrichment of PPARγ binding motifs and functional studies confirm that this promoter is regulated by PPARγ. Consequently, we demonstrate that a novel PPARγ inverse agonist is capable of repressing IGF-1 promoter activity and reducing growth and clonogenic potential of C1/M2-positive cell lines that exhibit high PGC-1α4 expression. Collectively, our results reveal a novel therapeutic vulnerability in salivary MEC cells that may extend more broadly to other cancers that exhibit dysregulated CREB activity. Citation Format: Adele M. Musicant, Kshitij P. Sharma, Erin C. Henry, Jason Tasoulas, Ricardo Padilla, Monideepa Sengupta, Colin Flaveny, Antonio L. Amelio. The CRTC1/MAML2 oncogene induces a PGC-1a splice variant that sensitizes mucoepidermoid carcinoma cells to PPARg inhibition [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 874.