GNAS Mutations Research Articles

Approach to Determining Etiology of Hypophosphatemia in a Patient with Coexisting Phosphaturic Mesenchymal Tumor and Fibrous Dysplasia

Abstract Dysregulated fibroblast growth factor-23 (FGF23) production is a demonstrated cause of hypophosphatemia and osteomalacia. Diseases associated with these conditions include phosphaturic mesenchymal tumor (PMT) causing tumor induced osteomalacia (TIO), various forms of rickets, and fibrous dysplasia (FD). Coexistence of two conditions that can increase FGF23 concentrations is rare. We report a case of a 79-year-old man who presented with rib and right flank pain. Imaging revealed bone lesions in the right iliac wing, left supra-acetabular area, and L4 vertebral body. Biopsies showed a right iliac PMT and left supra-acetabular FD. Cryoablation of both lesions resolved the phosphaturia with normalization of phosphorus level. Coexistence of PMT and FD in this patient with hypophosphatemia raised questions about the source of the FGF23, meaning of co-existence of PMT and FD in the same patient and, about the nature of the third lesion in the L4 vertebral body. Using FGF23 mRNA chromogenic in situ hybridization, we identified the PMT, rather than the FD, as the source of FGF23. Lack of GNAS mutation in the PMT suggested it being independent of FD. Assessment by the intact FGF23: total FGF23 ratio as well as gallium-DOTATATE scan suggested that the vertebral body lesion could represent FD. Other than understanding difference in underlying molecular processing of FGF23 in PMT and FD, testing for mutations, imaging studies as well as in situ hybridization helped solve the questions arising from this unique case of coexistence of PMT and FD.

EPCO-35. GENOMIC CHARACTERIZATION OF GROWTH HORMONE SECRETING PITUITARY ADENOMAS

Abstract BACKGROUND Pituitary adenomas (PAs) are the second most common brain tumors in adults with prevalence ranging from 80 to 100 per 100,000 individuals. Of these, 9% to 14% are growth hormone (GH)-secreting PAs. While recurrent somatic GNAS mutations are identified in approximately half of sporadic GH-secreting PAs, the remaining cases are not well-characterized. This study aims to expand the genomic profile of GH-secreting PAs and explore correlations between molecular and clinical features. METHODS Whole exome sequencing (WES) was performed on 19 tumors with matching blood samples from consenting patients, achieving mean coverages of 262.74X for tumor samples and 112.43X for blood samples. Somatic variants, including single nucleotide variants (SNVs), short insertions/deletions (INDELs), and copy number variations (CNVs), were identified, and analyzed using protocols established by our institution. Genomic instability was assessed by calculating the percentage of the genome displaying loss-of-heterozygosity (LOH). Clinical data were collected and analyzed to establish genomic correlations. RESULTS The cohort comprised 19 GH-secreting PAs, with a mean age of 46 years at surgery, and was predominantly female (78.9%). The cohort was enriched for macroadenomas, with a mean tumor size of 18.4 mm. WES revealed a mean somatic mutation count of 20.4 (range 7-79), with 47% of cases harboring recurrent GNAS mutations. The mean alteration by LOH across the cohort was 11.13% (range: 0-44.80%) and did not show a statistically significant difference between cases with GNAS mutations and GNAS-wildtype cases (7.71% vs. 14.21%, respectively). Chromosomes 3, 8, 16, 22q were frequently affected by CNV/LOH events. CONCLUSION Comprehensive genomic characterization, including assessment of genomic instability through CNV/LOH analysis, is critical for better understanding the pathogenesis of GH-secreting PAs. This study underscores the importance of detailed genomic profiling in larger cohorts for improving the diagnosis and management of these tumors.

Bronchial salivary gland-type mucinous adenocarcinoma harboring a GNAS mutation: a novel lung cancer entity? A case report.

Bronchial salivary gland-type mucinous adenocarcinoma harboring a GNAS mutation: a novel lung cancer entity? A case report.

Somatic GNAS mutations in acromegaly: prevalence, clinical features and gender differences

Background: Somatic GNAS mutations are acknowledged as a significant etiological factor for acromegaly. However, the relationship between GNAS mutation status, clinical characteristics and gender has not been adequately investigated. This study aims to address these gaps by examining GNAS mutations and delineating the detailed clinical profile of affected patients within a Chinese acromegaly cohort. Methods: Our study encompassed 97 individuals newly diagnosed with acromegaly, who underwent surgical treatment between May 2015 and January 2022. We obtained DNA from frozen pituitary adenomas to screen for GNAS hotspot mutations and assessed the associated clinical characteristics. Results: In our cohort, 44.3% (43/97) of patients exhibited somatic GNAS mutations. Patients with mutations were predominantly male (58.1% vs. 33.3%, p=0.015), experienced longer diagnosis delays [72.0 (48.0, 120.0) vs 36.0 (21.0, 75.0) months, p=0.002], had smaller maximum tumor diameters (1.75±0.83 vs. 2.23±0.89 cm, p=0.008), and demonstrated higher rates of GH secretion per unit tumor volume [18.93 (9.67, 30.12) vs 10.91 (2.80, 20.40) ng/mL/cm3, p=0.005]. Regarding gender-specific differences, GNAS mutations in male patients were linked to significantly higher baseline GH levels [24.40 (14.40, 36.30) vs. 10.55 (5.25, 16.95) ng/mL, p=0.002], while female patients with mutations had notably smaller tumor sizes (1.55±0.55 cm vs. 2.32±0.85 cm, p<0.001). Conclusion: GNAS mutations are prevalent among Chinese acromegaly patients, correlating with reduced pituitary tumor sizes and enhanced GH secretion functions. Our findings underscore the influence of gender on the clinical manifestations of GNAS mutations. Accordingly, we recommend that future clinical and foundational researches on acromegaly give heightened consideration to gender-specific differences.

GNAQ/GNA11-Related Benign and Malignant Entities-A Common Histoembriologic Origin or a Tissue-Dependent Coincidence.

Uveal melanoma (UM), recognized as the most prevalent primary intraocular malignancy in adults, is primarily driven by mutations in the GNAQ and GNA11 genes. These genetic alterations are also implicated in other conditions, which exhibit distinct morphological characteristics. In this article, we investigate the role of GNAQ and GNA11 mutations across varied disorders (e.g., UM, skin blue nevi, and hemangiomas), emphasizing the shared pathogenic mechanisms that connect them despite their differing clinical manifestations. By investigating the molecular pathways affected by these mutations, we provide insights into the potential for targeted therapies that could address not only UM but also other disorders associated with GNAQ/GNA11 mutations. Moreover, we discuss the role of SOX10-positive perivascular cells that may be implicated in the complex pathophysiology of GNAQ/GNA11-related entities. Understanding the common molecular foundation of these conditions opens new ways for research and treatment opportunities, potentially leading to more effective, personalized therapeutic strategies.

Circumscribed choroidal hemangioma in Sturge-Weber syndrome

We report on a19-year-old patient with Sturge-Weber syndrome (SWS), accompanied by aNaevus flammeus, secondary glaucoma, and glaucomatous optic atrophy of the right eye. The painful and blind eye was enucleated. Histopathological analysis revealed acircumscribed choroidal hemangioma around the optic nerve and asmaller extrascleral hemangioma. Molecular genetic testing excluded GNA11, GNAQ, or GNAS mutations. Our work illuminates the clinical, histological, and molecular genetic aspects of this rare case, contributing to the differential diagnosis of ocular conditions in patients with SWS.

Cyclin-Dependent Kinase 4/6 Inhibition as a Novel Therapy for Peritoneal Mucinous Carcinomatosis With GNAS Mutations.

Mucinous neoplasms of the gastrointestinal tract are characterized by a propensity for metastasis to the peritoneum, resulting in peritoneal mucinous carcinomatosis (PMC). A subset of these tumors, most often originating in the appendix, harbor mutations in the GNAS oncogene. While the natural history of GNAS-mutant PMC varies, patient outcomes are generally poor, as is response to cytotoxic chemotherapy. The purpose of this study was to evaluate the clinical efficacy of single-agent palbociclib, a cyclin-dependent kinase (CDK)4/6 inhibitor, in patients with GNAS-mutant PMC. We enrolled 16 patients with PMC in a single-arm personalized cancer therapy trial. For all patients, tumor tissue and/or circulating tumor DNA genomic profiling using next-generation sequencing and, when possible, PD-L1 expression, tumor mutational burden, and microsatellite instability status was assessed. Twelve of 16 patients had previous disease progression on at least one previous line of chemotherapy. The primary tumor was appendix in 13 patients, unknown in two patients, and pancreas in one patient. Eleven cases were classified as low grade, and five as high grade. In 13 of 16 patients, we observed a decrease in carcinoembryonic antigen (CEA), and in six patients, the CEA declined by >50%. As measured by clinical and modified peritoneal RECIST criteria, 50% of evaluable patients had stable disease after 12 months of palbociclib. At a median follow-up of 17.6 months, median survival has not been reached. Clinical response to CDK4/6 inhibition was mirrored in tumors with GNAS mutation and mucinous histology using an ex vivo preclinical platform. CDK4/6 inhibition with palbociclib had clinical activity in PMC characterized by mutations in GNAS that was superior to that previously reported with cytotoxic chemotherapy. CDK4/6 inhibition is a novel therapeutic strategy worthy of further evaluation in this subgroup of gastrointestinal neoplasms.

Primary jugular foramen fibrous dysplasia: surgically nuanced video of extradural infratemporal transjugular approach. Illustrative case.

Fibrous dysplasia of the bone is a disease caused by a somatic GNAS mutation that affects craniofacial bones and can have a mass effect on different neurovascular structures. The authors present the first case of primary jugular foramen fibrous dysplasia with occlusion of the transverse and sigmoid sinuses. A 33-year-old man presented with a history of dizziness and occasional dysphagia over the past year. Magnetic resonance imaging showed a uniform enhanced mass in the left jugular foramen, with complete blockage of the adjacent transverse and sigmoid sinuses. The computed tomography scan revealed a cystic bone lesion of the jugular foramen. The patient underwent a gross-total removal of the tumor through an infratemporal transjugular approach with complete preservation of the lower cranial nerves. This first reported case of primary jugular foramen fibrous dysplasia highlights the importance of considering this diagnosis when evaluating jugular fossa lesions. Understanding the anatomy of the infratemporal and jugular fossae, along with proficiency in microsurgical techniques, is essential for removing such tumors while preserving cranial nerve functions and the patient's quality of life. https://thejns.org/doi/10.3171/CASE24396.

Anlotinib treatment for rapidly progressing pediatric embryonal rhabdomyosarcoma in the maxillary gingiva: a case report

BackgroundEmbryonal rhabdomyosarcoma (ERMS) is a highly aggressive form of soft-tissue sarcoma that predominantly affects children. Due to limited benefits and resistance to therapy, there is an unmet need to explore alternative therapeutic strategies.Case presentationIn this report, we present a rare case of pediatric ERMS located on the right side of the maxillary gingiva. A composite reference guide integrating clinical, radiographic, and histopathologic findings was used for a definitive diagnosis. Targeted next-generation sequencing of tumor biopsy was performed to identify genetic alterations. A 12-year-old female was admitted to the Pediatric Intensive Care Unit (PICU) and underwent a tracheotomy to relieve asphyxiation caused by a 5.5 cm diameter mass compressing the tongue root and pharyngeal cavity. Hematoxylin and eosin staining revealed a hybrid morphology characterized by clusters of round and spindle cells. Further immunohistochemistry assays indicated positive immunoreactivity for desmin, myogenin, and MyoD1. Various genetic alterations were identified, including mutations in GNAS, HRAS, LRP1B, amplification of MDM2 and IGF1R, and two novel IGF1R fusions. Negative PAX-FOXO1 fusion status supported the clinical diagnosis of ERMS. Initial treatment involved standard chemotherapy; however, the tumor persisted in its growth, reaching a maximum volume of 12 cm × 6 cm × 4 cm by the completion of treatment. Subsequent oral administration of anlotinib yielded a significant antitumor response, characterized by substantial tumor necrosis and size reduction. Following the ligation of the tumor pedicle and its removal, the patient developed a stabilized condition and was successfully discharged from PICU.ConclusionsOur study highlights the importance of accurate diagnosis established on multifaceted assessment for the effective treatment of ERMS. We present compelling evidence supporting the clinical use of anlotinib as a promising treatment strategy for pediatric ERMS patients, especially for those resistant to conventional chemotherapy.

7211 Clinical and Molecular Characterization Of An Aldosterone-Producing Adenoma Harboring Double Somatic Mutations In CTNNB1 and GNA11

Abstract Disclosure: A. Blinder: None. K. Nanba: Grant Recipient; Self; AstraZeneca. A. Udager: None. Y. Hirokawa: None. T. Miura: None. H. Okuno: None. K. Moriyoshi: None. Y. Yamazaki: None. H. Sasano: None. A. Yasoda: None. N. Satoh-Asahara: None. W.E. Rainey: None. T. Tagami: None. Background: Somatic activating mutations in CTNNB1, encoding β-catenin, have been detected in a small subset of aldosterone-producing adenomas (APAs). As a possible pathogenesis, an association of CTNNB1-mutated APA with pregnancy and menopause has been proposed. A recent study reported double somatic mutations in CTNNB1 and GNA11/Q, encoding guanine nucleotide-binding protein subunits alpha-11 and alpha-Q, in APA. However, due to its rare incidence, clinical and molecular features of APA associated with these mutations have not been well characterized. Herein, we report a case of APA harboring somatic CTNNB1 and GNA11 mutations. Clinical Case: A 46-year-old Japanese woman presented with hypertension and hypokalemia. She had two pregnancies in the past but had no history of pregnancy-induced hypertension. She had regular menstrual cycles at presentation. Laboratory testing showed elevated plasma aldosterone concentration with suppressed plasma renin activity. She was diagnosed as having primary aldosteronism based on the results of a captopril challenge test. Adrenal computed tomography revealed a 2 cm right adrenal mass. Adrenal venous sampling indicated excess aldosterone production from the right adrenal gland. She underwent right laparoscopic adrenalectomy. Histologic diagnosis of the resected tumor was adrenocortical adenoma based on the criteria of Weiss. Notably, Ki-67 labeling index was high (6% at hotspots). After surgery, her blood pressure and serum potassium both normalized. According to the primary aldosteronism surgical outcome (PASO) study criteria, PA remained clinically and biochemically cured at follow-up 2.5 years after surgery. Results: Immunohistochemistry (IHC) showed high and diffuse expression of aldosterone synthase (CYP11B2) within the tumor, whereas immunoreactivity of 17α-hydroxylase (CYP17A1) and 11β-hydroxylase (CYP11B1), both required for cortisol biosynthesis, was markedly low. VSNL1, a marker for the zona glomerulosa (ZG) where physiologic aldosterone biosynthesis occurs, was highly expressed within the tumor. CYP11B2 IHC-guided tumor capture followed by targeted next-generation sequencing identified double somatic CTNNB1 (p.D32Y) and GNA11 (p.Q209H) mutations. Quantitative real-time RT-PCR revealed high tumor expression of LHCGR (LH receptor) and GNRHR (GNRH receptor) mRNA levels compared with those in adjacent normal adrenal (148-fold and 56-fold, respectively). Immunofluorescence staining of the tumor revealed the presence of activated β-catenin, consistent with features of the normal ZG. Conclusions: Our study indicates that an APA with double somatic mutations in CTNNB1 and GNA11 has characteristics of the ZG and could occur in adults with no clear association with pregnancy or menopause. Presentation: 6/3/2024

12395 Continuous Glucose Monitoring In Pseudohypoparathyroidism Type 1a

Abstract Disclosure: J. Tamaroff: None. A.E. Lee: None. A.H. Shoemaker: None. Background: Pseudohypoparathyroidism type 1A (PHP1A), due to heterozygous mutations in GNAS, is a rare disorder that leads to multi-hormone resistance, cognitive impairment, and early-onset obesity. Individuals with PHP1A have dysglycemia on oral glucose tolerance tests and increased rates of type 2 diabetes (T2DM). Individuals with rare diseases, like PHP1A, may travel significant distances for specialized clinical or research care. Wearable technology may alleviate barriers and provide useful information for clinical care or for use as potential biomarkers. The objective of this study is to evaluate glycemia in individuals with PHP1A and feasibility of utilizing continuous glucose monitors (CGMs) in this population. Methods: Observational study of individuals with PHP1A (3R01DK118407-03S1). CGMs (Dexcom Pro, Dexcom Inc, San Diego, CA) were placed on participants’ abdomens, typically by a family member, over secure-video call with study staff. CGMs collected data every 5 minutes for up to 10 days. Results: Seven participants (all female) with PHP1A without a diagnosis of diabetes had available data. Median age was 17 years (IQR: 14, 19; range: 8-23). Body mass index (BMI) categories (by percent of the 95th percentile for those under 18 years and BMI for adults) spanned from overweight to class 3 obesity. In terms of feasibility, 1 individual had to replace a CGM sensor due to an upcoming MRI and 1 individual had a “sensor failure” of unclear etiology. Both were able to place new CGMs. Individuals participated across 5 states in the United States. Median length of wear was 9.8 days (IQR 8.6, 9.9). Participants had a median average glucose of 104mg/dL (IQR 102, 111) and COV of 16% (15, 21). Percent of glucose > 140mg/dL was 5.0% (IQR: 1.8, 10.9; range:1.2-19.4%). One individual had 3.2% of glucose values ≥ 200mg/dL despite a normal hemoglobin A1c (HbA1c) level (5.5%). This level of hyperglycemia is qualitatively higher than published CGM data in healthy individuals. One study found individuals (6-24 years of age) had median percent of glucose values over 140mg/dL ranging from 1.2 to 2.4% with IQR values ranging from 0.3 to 4.4%, based on age categories.1Conclusions: In females with PHP1A, with overweight or obesity, CGM placement at home is a feasible way to collect real-world data. Participants with rare diseases often must travel for clinical and research care and CGMs may provide insight into glycemia without requiring an in-person visit. This “real-world” data mirrors research data reporting glycemia with normal HbA1c levels. The rate of hyperglycemia is higher than expected in some individuals with PHP1A though more data is needed. Ongoing studies will evaluate matched control participants and assess drivers of glycemia including inactivity and decreased sleep duration, as measured by actigraphy.

8294 Association between gene mutations and DNA methylation of CYP11B2 in aldosterone-producing adenoma

Abstract Disclosure: M. Kometani: None. R. Mizoguchi: None. M. Demura: None. K. Aiga: None. S. Konishi: None. D. Aono: None. S. Karashima: None. Y. Takeda: None. T. Yoneda: None. Context: Primary aldosteronism (PA) causes hypertension and cardiovascular complications. Recently, in aldosterone producing adenomas (APA), various genetic mutations have been identified. In addition, epigenetic mechanisms, such as DNA methylation, are also involved in excessive aldosterone production. Several studies have shown that aldosterone synthase (CYP11B2) is hypomethylated in APA. On the other hand, the relationship between specific genetic variants identified in APA and DNA methylation has not been fully clarified. Objective: To investigate the relationship between specific genetic mutations in APA and DNA methylation of CYP11B2. Methods: We analyzed 48 patients (female 23 cases) diagnosed with APA and treated between 2001 and 2022. First, Gene mutation analysis using next-generation sequencing was performed. KCNJ5, ATP1A1, ATP2B3, CACNA1D, and CACNA1H, which are known mutations in PA, and PRKACA, PRKA1A, GNAS, CTNNB1, and ARMC5, which are known mutations in Cushing’s syndrome, were evaluated. Next, DNA methylation analysis of the CYP11B2 promoter using pyrosequencing were performed using APA. We targeted three CpG regions near the transcription start site of CYP11B2. Results: The respective mean values for all patients were: age 52 years, systolic blood pressure 138 mmHg, diastolic blood pressure 87 mmHg, ARR 1,326, serum potassium level 3.4 mEq/L, and tumor diameter 15 mm. Genetic mutation analysis revealed KCNJ5 gene mutations in 33 of the 48 patients. Among the other cases, mutations in the CTNNB1 gene were found in three cases, mutations in the ATP1A1 gene in two cases, mutations in the CACNA1D gene in one case, and PRKACA gene mutations in one case. The remaining seven patients had no mutations in any of the analyzed genes. When DNA methylation of the promoter region of CYP11B2 was analyzed in APAs with and without mutations in KCNJ5, we found that in all three CpG regions, DNA methylation rate was significantly reduced in APAs with mutations in KCNJ5 gene (CpG1 22% vs. 30%, CpG2 42% vs. 73%, CpG3 47% vs. 75%, respectively). Conclusions: The most common genetic mutation in APA was the KCNJ5 mutation; APA with the KCNJ5 mutation had significantly lower methylation rates than CYP11B2. This suggests that genetic mutations in APA affect DNA methylation and result in hormone overproduction. Presentation: 6/3/2024

Targeted Genetic Sequencing Analysis of 223 Cases of Pseudomyxoma Peritonei Treated by Cytoreductive Surgery and Hyperthermic Intraperitoneal Chemotherapy Shows Survival Related to GNAS and KRAS Status.

Pseudomyxoma peritonei (PMP) is an unusual condition with unique behaviour caused by a mucinous neoplasm, usually arising from the appendix. The aim of this study was to evaluate the prevalence of genomic alterations in clinical specimens of PMP using a targeted assay and correlate the findings with clinical, pathological and outcome data. Sequencing data from 223 patients were analysed. The median follow-up interval was 48 months. The primary neoplasm was appendiceal in 216 patients, ovarian in 4, urachal in 2 and renal in one. We confirmed common mutations in GNAS and KRAS (42% each) with significant co-occurrence of variants in these genes. TP53 mutations were found in 8%. Other mutations were rare but included novel mutations in BAP1 and ERBB4. Of 17 patients with acellular peritoneal mucin, 6 (35%) were positive for DNA mutations. The non-appendiceal cases generally showed a similar mutational landscape to the appendiceal lesions with GNAS and KRAS commonly mutated, although one urachal lesion showed multi-hit TP53 mutation without variants in either GNAS or KRAS. Survival was significantly associated with the grade of the primary neoplasm, the grade of the peritoneal disease, the completeness of cytoreduction score and with mutation in either GNAS, KRAS or both. The hazard ratio (HR) associated with mutation in GNAS and/or KRAS was 1.87 (p = 0.004). Survival outcome was more closely associated with the grade of the peritoneal disease than with the grade of the primary neoplasm. Our findings support the developing concept that mutational analysis may provide prognostic information in patients with PMP.

Molecular Profiling of Low-Grade Appendiceal Mucinous Neoplasms (LAMN).

Low-grade appendiceal mucinous neoplasia (LAMN) represents a relatively rare tumor of the appendix typically diagnosed incidentally through appendectomy for acute appendicitis. In cases where perforation occurs, mucinous content may disseminate into the abdominal cavity, leading to the development of pseudomyxoma peritonei (PMP). The primary objective of this study was to elucidate the molecular characteristics associated with various stages of LAMN and PMP. DNA was extracted from LAMN, primary PMPs, recurrent PMPs, and adenocarcinomas originating from LAMN. The subsequent analysis involved the examination of mutational hotspot regions within 50 cancer-related genes, covering over 2800 COSMIC mutations, utilizing amplicon-based next-generation sequencing (NGS). Our findings revealed activating somatic mutations within the MAPK-signaling pathway across all tumors examined. Specifically, 98.1% of cases showed mutations in KRAS, while one tumor harbored a BRAF mutation. Additionally, GNAS mutations were identified in 55.8% of tumors, with no significant difference observed between LAMN and PMP. While LAMN rarely displayed additional mutations, 42% of primary PMPs and 60% of recurrent PMPs showed additional mutations. Notably, both adenocarcinomas originating from LAMN showed mutations within TP53. Furthermore, 7.7% (4/52) of cases exhibited a potentially targetable KRAS G12C mutation. In four patients, NGS analysis was performed on both primary PMP and recurrent PMP/adenocarcinoma samples. While mutations in KRAS and GNAS were detected in almost all samples, 50% of recurrent cases displayed an additional SMAD4 mutation, suggesting a notable alteration during disease progression. Our findings indicate two key points: First, mutations within the MAPK pathway, particularly in KRAS, are evident across all tumors, along with a high frequency of GNAS mutations. Second, progression toward PMP or adenocarcinoma is associated with an accumulation of additional mutations within common oncogenic pathways.

Diagnosis and management of pituitary adenomas in children and adolescents.

Pituitary adenomas (PAs)-also now called pituitary neuroendocrine tumours or Pit-NETS-are rare in children and adolescents and exceptional below the age of 10. Most evidence-based high-quality data are derived from larger studies in adult patients. We will review recent knowledge on the epidemiology, clinical features, diagnosis, and treatment modalities of the different types of pituitary adenomas diagnosed in children and adolescents, emphasizing the many reasons why these cases should be discussed within pituitary-specific multidisciplinary teams with experts from both paediatric and adult practice. Paediatric PA presents multiple peculiarities that may challenge their adequate management. They are overall proportionally larger and more aggressive than in adults, with potential mass effects including hypopituitarism. Hormonal hypersecretion is frequent, resulting in clinical syndromes affecting normal growth and pubertal development. Prolactinomas represent the most frequent subtype of PA found during childhood, followed by adrenocorticotropin (ACTH) and growth hormone (GH)-secreting adenomas, while clinically non-functioning adenomas are exceptionally diagnosed before the age of 16. The occurrence of a pituitary tumour in a young individual should also prompt genetic testing in each case, searching for either germline mutations in one of the known genes that may drive inherited/familial PA (such as the multiple endocrine neoplasia type 1 or MEN1 gene, or the aryl hydrocarbon receptor interacting protein or AIP gene), or for a mosaic activating mutation of GNAS as found in the McCune-Albright syndrome.

Abstract C030: Evolutionary and epistatic analyses reveal genic interactions with KRAS during malignant progression of pancreatic ductal adenocarcinoma

Abstract Pancreatic ductal adenocarcinoma (PDAC) patients face poor prognoses attributable to delayed disease detection, resulting in distant metastases and thereby reducing treatment efficacy. The challenge of detecting PDAC lesions during early stages emanates from an inauspicious trifecta of clinical factors: early-stage malignancies are often asymptomatic, existing biomarkers are insufficiently sensitive, and the physical location of the pancreas stymies reliable screening. A promising strategy towards improving outcomes is the resection of high-risk, pre-malignant lesions deemed likely to progress into carcinomas. Intraductal papillary mucinous neoplasms (IPMNs) are both large enough to be detected during abdominal imaging and can originate PDAC lesions. However, a patient may have many IPMN cysts, many of which will never progress. As pancreatic resection carries with it a high risk of morbidity, distinguishing the the evolutionary trajectories of IPMNs that will and will not progress could inform treatment strategies. Additionally, these trajectories may serve as disruptable targets to manage pre- neoplastic lesions, preventing their progression to PDAC. The vast majority PDAC cases contain mutations in KRAS and GNAS with secondary driver mutations in TP53, SMAD4, CDKN2A, and RNF43. Recent work has compared the frequency of these mutations in PDAC with low-grade and high-grade IPMN lesions, finding that they more common in high than low- grade lesions. Interestingly, unlike KRAS or GNAS, KLF4 mutations are prevalent in low-grade IPMNs, rare in high-grade IPMNs, and almost never observed in full-fledged carcinoma, suggesting distinct evolutionary trajectories possibly mediated by epistatic interactions between KLF4 and KRAS. However, the prevalence of a mutation is not dispositive as to its importance in tumorgenesis. Mutations in TTN, for instance, are frequently observed in PDAC and other cancers, but are widely considered to play a modest role, if any, in these cancers. To understand the contribution of a mutation to the evolution of cancer, we must instead deconvolve selection from baseline mutation rate across genomic sites and among patients to distinguish truly oncogenic mutations from mutations that occur frequently merely due to high underlying mutational rates. Here, we quantify the evolutionary and epistatic interplay between KRAS, KLF4, and other frequent mutations in IPMNs and PDAC during malignant transition. First, we report the cancer effect sizes of single-nucleotide variants in IPMNs at varying dysplastic stages. Then, we infer the synergistic and antagonistic interactions between driver mutations, providing insight into the order in which driver mutations occur. We then corroborate this epistasis-inferred ordering with the ordering of mutations recovered from ancestral state reconstruction derived from time-calibrated phylogenies. Lastly, we probe the mutational processes most responsible for conferring highly oncogenic mutations in IPMNs and PDACs to identify potentially actionable or preventable pathways of disease progression. Metabolism Citation Format: Nic Fisk, Derek Song, Margaret Moore, Cole G Jensen, Vincent L. Cannataro, Mofeed Nagib, Jeffrey D Mandell, Luisa Escobar-Hoyos, John W Kunstman, Jeffrey P Townsend. Evolutionary and epistatic analyses reveal genic interactions with KRAS during malignant progression of pancreatic ductal adenocarcinoma [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Advances in Pancreatic Cancer Research; 2024 Sep 15-18; Boston, MA. Philadelphia (PA): AACR; Cancer Res 2024;84(17 Suppl_2):Abstract nr C030.

Abstract PR-02: Uncovering molecular differences in pancreatic ductal adenocarcinoma tissues from Black and White patients in the US

Abstract Background: Pancreatic cancer (PC) is among the leading causes of cancer-related deaths in the United States, with a 5-year survival rate of approximately 13%. Previous studies reported higher PC incidence and mortality rates among Black or African American (BAA) patients in comparison to White patients. Disadvantaged socioeconomic status (SES) and environmental exposure to chemicals are factors contributing to racial disparities in pancreatic cancer. Whether and how biological pathways play roles in disparities in pancreatic cancer is unclear. The understanding of molecular features associated racial backgrounds in pancreatic cancer will have significant impacts on both scientific inquiry on cancer biology and clinical management of pancreatic malignancy. In this study, we examined oncogene alterations and PD-L1 expression in pancreatic cancer patients of diverse racial backgrounds. Methods: We conducted our study by analyzing clinical test results of patients through a collaboration with Tempus Labs. In total, 4,249 pancreatic cancer patients’ (White: 3797 and BAA: 452) information were included in this study. DNA target panel sequencing was performed to identify genomic mutations. Genomic microsatellite instability (MSI) and tumor mutational burdens (TMB) were assessed. We also evaluated PD-L1 expression by immunohistochemistry. Results: DNA sequencing analysis revealed differential gene mutation profiles between White and BAA patients. We observed higher rates of KRAS (79.2% vs. 74.2%, q=0.14), TP53 (69.9% vs. 61.9%, q=0.014), KMT2C (6.9% vs. 2.3%, q=0.001), RNF43 (6% vs. 3.7%, q=0.14), and KMT2D (4.4% vs. 2.8%, q=0.3) mutations among BAA patients compared to White patients whereas fewer GNAS (0.2% vs 1.6%, q=0.14) mutation occur in the BAA group. Importantly, the KRAS mutant allele KRASG12R was significantly enriched in BAA compared to White patients (14.4% vs. 10.1%). Next, we compared the TMB levels and found that BAA patients showed higher average TMB levels when compared to White patients. Further, we determined the expression of PD-L1 between the two racial groups and observed BAA patients had more frequent PD-L1 overexpression than White patients (13.2% vs. 8.6%, p<0.05). Interestingly, the race associated difference in PD-L1 expression was even more remarkable in female groups (14.1% vs. 8%, p<0.05). Conclusion: We observed differences in mutation profiles of oncogenes between BAA and White patients, suggesting that such molecular-level changes may contribute to the higher incidence among BAA patients. Additionally, higher frequencies of PD-L1 upregulation in BAA patients implicate racial backgrounds influence tumor microenvironment regulation in pancreatic cancer patients. It is imperative to improve racial diversity in translational and clinical studies. Citation Format: Saurabh Mandal, Emily A Teslow, Minxuan Huang, Swathi Sridhar, Howard Crawford, Melissa C Stoppler, Albert Levin, Ling Huang. Uncovering molecular differences in pancreatic ductal adenocarcinoma tissues from Black and White patients in the US [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Advances in Pancreatic Cancer Research; 2024 Sep 15-18; Boston, MA. Philadelphia (PA): AACR; Cancer Res 2024;84(17 Suppl_2):Abstract nr PR-02.

GNAS, not a Highly Mutated Gene, Has Prognostic Significance and Carcinogenic Effects in Osteosarcoma.

Osteosarcoma is a prevalent and aggressive primary malignant bone tumor affecting children and adolescents. Despite advancements in sequencing technologies, there remains a lack of reliable prognostic biomarkers and effective targeted therapies for osteosarcoma. This study focuses on identifying key prognostic genes, particularly the role of GNAS, in osteosarcoma progression. Bioinformatics analyses were performed on osteosarcoma datasets from the Gene Expression Omnibus (GEO). Differential gene expression analysis, weighted correlation network analysis (WGCNA), and survival analysis identified potential prognostic hub genes. The expression and function of these genes were validated through immunohistochemistry and animal experiments. Specifically, the role of GNAS was investigated through siRNA-mediated knockdown in osteosarcoma cell lines and nude mice models. Five hub genes (PROP1, GNAS, CYP4F2, LHX3, CNGB1) were identified as significantly related to osteosarcoma prognosis. Among these, GNAS was found to be highly expressed in osteosarcoma tissues compared to normal tissues. Immunohistochemical analysis confirmed the elevated expression of GNAS in osteosarcoma samples. GNAS mutation analysis revealed a low mutation rate in osteosarcoma, suggesting its oncogenic role is independent of mutational status. Animal experiments demonstrated that knocking down GNAS significantly inhibited tumor growth and induced apoptosis in osteosarcoma cells. GNAS is highly expressed in osteosarcoma and associated with poor prognosis, acting as an oncogene in osteosarcoma progression. Targeting GNAS could be a potential therapeutic strategy for osteosarcoma. Further studies on GNAS-related signaling pathways may provide deeper insights into the molecular mechanisms driving osteosarcoma malignancy.

Metabolic reprogramming by mutant GNAS creates an actionable dependency in intraductal papillary mucinous neoplasms of the pancreas

BackgroundOncogenic ‘hotspot’ mutations of KRAS and GNAS are two major driver alterations in intraductal papillary mucinous neoplasms (IPMNs), which are bona fide precursors to pancreatic ductal adenocarcinoma. We previously reported...

KRAS and GNAS mutations in cell-free DNA and in circulating epithelial cells in patients with intraductal papillary mucinous neoplasms-an observational pilot study.

Intraductal papillary mucinous neoplasms (IPMNs) are potential precursor lesions of pancreatic cancer. We assessed the efficacy of screening for KRAS proto-oncogene, GTPase (KRAS), and GNAS complex locus (GNAS) mutations in cell-free DNA (cfDNA)-using digital droplet polymerase chain reaction (ddPCR) and circulating epithelial cell (CEC) detection-as biomarkers for risk stratification in IPMN patients. We prospectively collected plasma samples from 25 resected patients at risk of malignant progression, and 23 under clinical surveillance. Our findings revealed KRAS mutations in 10.4% and GNAS mutations in 18.8% of the overall cohort. Among resected IPMN patients, KRAS and GNAS mutation detection rates were 16.0% and 32.0%, respectively, whereas both rates were 4.0% in conservatively managed IPMN. GNAS mutations in cfDNA were significantly more prevalent in resected IPMN (P = 0.024) compared with IPMN under surveillance. No CECs were detected. The absence of KRAS and GNAS mutations could be a reliable marker for branch duct IPMN without worrisome features. The emergence of GNAS mutations could prompt enhanced imaging surveillance. Neither the presence of established worrisome features nor GNAS or KRAS mutations appear effective in identifying high-grade dysplasia among IPMN patients.