Biosimulation Using the Cellworks Computational Omics Biology Model (CBM) Identifies Immune Modulation As a Key Pathway for Predicting Azacitidine (AZA) Response in Myelodysplastic Syndromes (MDS)

Background: DNA methyltransferase inhibition (DNMTi) with the hypomethylating agents (HMA) azacitidine (AZA) or decitabine, remains the mainstay of therapy for the majority of high-risk Myelodysplastic Syndromes (MDS) patients. Nevertheless, only 40-50% of MDS patients achieve clinical improvement with DNMTi. There is a need for a predictive clinical approach that can stratify MDS patients according to their chance of benefit from current therapies and that can identify and predict responses to new treatment options. Ideally, patients predicted to be non-responders (NR) could be offered alternative strategies while being spared protracted treatment with HMA alone that has a low likelihood of efficacy. Recently, an intriguing discovery of immune modulation by HMA has emerged. In addition to the benefits of unsilencing differentiation genes and tumor suppressor genes, HMA's reactivate human endogenous retroviral (HERV) genes leading to viral mimicry and upregulation of the immune response as a major mechanism of HMA efficacy. Although the PD-L1/PD1 blockade plus HMA has been recognized as a beneficial combination, there are no established markers to guide decision-making. We report here the utility of immunomic profiling of chromosome 9 copy number status as a significant mechanism of immune evasion and HMA resistance. Methods: 119 patients with known clinical responses to AZA were selected for this study. Publicly available data largely from TCGA and PubMed was utilized for this study. The aberration and copy number variations from individual cases served as input into the Cellworks Computation Omics Biology Model (CBM), a computational biology multi-omic software model, created using artificial intelligence heuristics and literature sourced from PubMed, to generate a patient-specific protein network map. Disease-biomarkers unique to each patient were identified within protein network maps. The Cellworks Biosimulation Platform has the capacity to biosimulate disease phenotypic behavior and was used to create a disease model and then conduct biosimulations to measure the effect of AZA on a cell growth score comprised of a composite of cell proliferation, viability, apoptosis, metastasis, and other cancer hallmarks. Biosimulation of drug response was conducted to identify and predict therapeutic efficacy. Results: Although AZA treatment increased tumor associated antigens and interferon signaling, it also increased PD-L1 expression to inactivate cytotoxic CD8(+) T cells. Copy number alterations of the chromosome 9p region were found to significantly drive PD-L1 expression with multiple genes such as CD274, IFNA1, IFNA2, JAK2, PDCD1LG and KDM4C playing a role in PD-L1 regulation further increasing immune suppression (Figure 1). Among 6 cases of chromosome 9p aberration in this dataset, 9p amp (n=2) were clinical non-responders (NR) while 9p del (n=4) were responders (R) to AZA. In principle, checkpoint immunotherapy could improve outcomes for patients with 9p abnormalities. Additionally, copy number variation loss of key genes located on chromosome 16 involved in antigen processing and presentation such as CIITA, CTCF, IRF8, PSMB10, NLRC5, and SOCS1 were found to negatively impact AZA sensitivity (NR=4; R=0); these patients would also be unlikely to respond to checkpoint immunotherapy. Also, aberrations in melanoma antigen gene (MAGE) family proteins (NR=2; R=O), and STT3A (NR=1; R=5) were found to impact AZA efficacy by decreasing antigen processing on tumor cells. Conclusion: Based on the results from the Cellworks Biosimulation Platform applied to the CBM, copy number variants of chromosome 9p and 16 can be converted into CBM-derived biomarkers for response to checkpoint immunotherapy in combination with HMA. Our results support a future prospective evaluation in larger cohorts of MDS patients. Figure 1 Figure 1. Disclosures Howard: Servier: Consultancy; Cellworks Group Inc.: Consultancy; Sanofi: Consultancy, Other: Speaker fees. Kumar: Cellworks Group Inc.: Current Employment. Castro: Bugworks: Consultancy; Exact sciences Inc.: Consultancy; Guardant Health Inc.: Speakers Bureau; Cellworks Group Inc.: Current Employment; Caris Life Sciences Inc.: Consultancy; Omicure Inc: Consultancy. Grover: Cellworks Group Inc.: Current Employment. Mohapatra: Cellworks Group Inc.: Current Employment. Kapoor: Cellworks Group Inc.: Current Employment. Tyagi: Cellworks Group Inc.: Current Employment. Nair: Cellworks Group Inc.: Current Employment. Suseela: Cellworks Group Inc.: Current Employment. Pampana: Cellworks Group Inc.: Current Employment. Lala: Cellworks Group Inc.: Current Employment. Singh: Cellworks Group Inc.: Current Employment. Shyamasundar: Cellworks Group Inc.: Current Employment. Kulkarni: Cellworks Group Inc.: Current Employment. Narvekar: Cellworks Group Inc.: Current Employment. Sahni: Cellworks Group Inc.: Current Employment. Raman: Cellworks Group Inc.: Current Employment. Balakrishnan: Cellworks Group Inc.: Current Employment. Patil: Cellworks Group Inc.: Current Employment. Palaniyeppa: Cellworks Group Inc.: Current Employment. Balla: Cellworks Group Inc.: Current Employment. Patel: Cellworks Group Inc.: Current Employment. Mundkur: Cellworks Group Inc: Current Employment. Christie: Cellworks Group Inc.: Current Employment. Macpherson: Cellworks Group Inc.: Current Employment. Marcucci: Abbvie: Other: Speaker and advisory scientific board meetings; Novartis: Other: Speaker and advisory scientific board meetings; Agios: Other: Speaker and advisory scientific board meetings.

First Case Report of Maternal Mosaic Tetrasomy 9p Incidentally Detected on Non-Invasive Prenatal Testing

Tetrasomy 9p (ORPHA:3390) is a rare syndrome, hallmarked by growth retardation; psychomotor delay; mild to moderate intellectual disability; and a spectrum of skeletal, cardiac, renal and urogenital defects. Here we present a Chinese female with good past health who conceived her pregnancy naturally. Non-invasive prenatal testing (NIPT) showed multiple chromosomal aberrations were consistently detected in two sampling times, which included elevation in DNA from chromosome 9p. Amniocentesis was performed and sent for chromosomal microarray, which was normal. Maternal karyotype revealed that mos 47,XX,+dic(9;9)(q21.1;q21.1)(24)/46,XX(9) presents mosaic tetrasomy for the short arm of chromosome 9p and is related to the NIPT results showing elevation in DNA from chromosome 9p. The pregnancy was uneventful, and the patient was delivered at term. Maternal samples were obtained at two different time points after delivery showed the same multiple chromosomal aberrations detected during pregnancy. This is a first report on an unusual case of mosaic isodicentric tetrasomy 9p in a healthy adult with normal intellect. With widespread adoption of NIPT for screening fetal aneuploidy and genome-wide copy number changes, a rise in incidental detection of maternal rare genetic syndrome will bring challenges in our current approach to genetic counselling and prenatal diagnosis.

Refinement of the critical genomic region for congenital hyperinsulinism in the Chromosome 9p deletion syndrome

Background: Large contiguous gene deletions at the distal end of the short arm of chromosome 9 result in the complex multi-organ condition chromosome 9p deletion syndrome. A range of clinical features can result from these deletions with the most common being facial dysmorphisms and neurological impairment. Congenital hyperinsulinism is a rarely reported feature of the syndrome with the genetic mechanism for the dysregulated insulin secretion being unknown. Methods: We studied the clinical and genetic characteristics of 12 individuals with chromosome 9p deletions who had a history of neonatal hypoglycaemia. Using off-target reads generated from targeted next-generation sequencing of the genes known to cause hyperinsulinaemic hypoglycaemia (n=9), or microarray analysis (n=3), we mapped the minimal shared deleted region on chromosome 9 in this cohort. Targeted sequencing was performed in three patients to search for a recessive mutation unmasked by the deletion. Results: In 10/12 patients with hypoglycaemia, hyperinsulinism was confirmed biochemically. A range of extra-pancreatic features were also reported in these patients consistent with the diagnosis of the Chromosome 9p deletion syndrome. The minimal deleted region was mapped to 7.2 Mb, encompassing 38 protein-coding genes. In silico analysis of these genes highlighted SMARCA2 and RFX3 as potential candidates for the hypoglycaemia. Targeted sequencing performed on three of the patients did not identify a second disease-causing variant within the minimal deleted region. Conclusions: This study identifies 9p deletions as an important cause of hyperinsulinaemic hypoglycaemia and increases the number of cases reported with 9p deletions and hypoglycaemia to 15 making this a more common feature of the syndrome than previously appreciated. Whilst the precise genetic mechanism of the dysregulated insulin secretion could not be determined in these patients, mapping the deletion breakpoints highlighted potential candidate genes for hypoglycaemia within the deleted region.

EARLY-ONSET GONADOBLASTOMA IN A 13-MONTH-OLD INFANT WITH 46,XY COMPLETE GONADAL DYSGENESIS IDENTIFIED WITH PRENATAL TESTING: A CASE OF CHROMOSOME 9p DELETION

Objective: Individuals with 46,XY complete gonadal dysgenesis (CGD) are at high risk of developing gonadal neoplasms. Chromosome 9p monosomy with deletion of the DMRT1 gene, a key transcription factor in testicular development, is one of the known causes of 46,XY CGD. Noninvasive prenatal testing (NIPT) is being increasingly used, and can identify disorders of sexual development (DSDs). Methods: We report the case of a 46,XY infant with phenotypically female external genitalia, müllerian structures including uterus and fallopian tubes, and bilateral streak gonads who was found to have unilateral gonadoblastoma at 13 months. 46,XY DSD was suggested prenatally when discordance between NIPT and fetal ultrasound was noted. Results: Genetic investigation revealed a deletion of 12.5 million base pairs at chromosome 9p24.3, which includes the doublesex and MAB-3-related transcription factor-1 ( DMRT1) gene. Conclusion: Current guidelines recommend gonadectomy at the time of diagnosis in cases of 46,XY CGD, and our patient had gonadoblastoma at 13 months. 46,XY DSD, including rare disorders such as CGD, will be increasingly identified before birth with more widespread use of NIPT, raising the question about the appropriate timing of gonadectomy in prenatal diagnoses. Our case supports the current recommendation to perform gonadectomy as early as possible after diagnosis.

Refinement of the critical genomic region for hypoglycaemia in the Chromosome 9p deletion syndrome

Background: Large contiguous gene deletions at the distal end of the short arm of chromosome 9 result in the complex multi-organ condition chromosome 9p deletion syndrome. A range of clinical features can result from these deletions with the most common being facial dysmorphisms and neurological impairment. Congenital hyperinsulinism is a rarely reported feature of the syndrome with the genetic mechanism for the dysregulated insulin secretion being unknown. Methods: We studied the clinical and genetic characteristics of 12 individuals with chromosome 9p deletions who had a history of neonatal hypoglycaemia. Using off-target reads generated from targeted next-generation sequencing of the genes known to cause hyperinsulinaemic hypoglycaemia (n=9), or microarray analysis (n=3), we mapped the minimal shared deleted region on chromosome 9 in this cohort. Targeted sequencing was performed in three patients to search for a recessive mutation unmasked by the deletion. Results: In 10/12 patients with hypoglycaemia, hyperinsulinism was confirmed biochemically. A range of extra-pancreatic features were also reported in these patients consistent with the diagnosis of the Chromosome 9p deletion syndrome. The minimal deleted region was mapped to 7.2 Mb, encompassing 38 protein-coding genes. In silico analysis of these genes highlighted SMARCA2 and RFX3 as potential candidates for the hypoglycaemia. Targeted sequencing performed on three of the patients did not identify a second disease-causing variant within the minimal deleted region. Conclusions: This study identifies 9p deletions as an important cause of hyperinsulinaemic hypoglycaemia and increases the number of cases reported with 9p deletions and hypoglycaemia to 15 making this a more common feature of the syndrome than previously appreciated. Whilst the precise genetic mechanism of the dysregulated insulin secretion could not be determined in these patients, mapping the deletion breakpoints highlighted potential candidate genes for hypoglycaemia within the deleted region.

P04.10 IDH-wildtype low grade gliomas: overall survival and prognostic indicators

BACKGROUND IDH-wildtype WHO grade II diffuse gliomas represent a rare subgroup of low grade tumors characterized by poor prognosis. The clinical and molecular profile associated with these tumors has not been fully elucidated yet, and the ongoing uncertainties regarding their biological behavior hamper to establish a standard of treatment. The aim of this study is to define the median overall survival and the main prognostic factors associated with this rare tumor entity. MATERIALS AND METHODS We performed a retrospective research in our center for all patients diagnosed with diffuse WHO grade II and III gliomas from 1976 to 2018. WHO grade II and III gliomas were divided into three molecular subgroups according to the IDH1/2 mutation and the 1p/19q codeletion status (1: IDH-mutant, 1p/19q codeleted; 2: IDH-mutant, 1p/19q non codeleted; 3: IDH-wildtype). We analyzed the clinical and molecular characteristics of the three subgroups, and then the clinical, radiological, histological and molecular features of IDH-wildtype WHO grade II gliomas. RESULTS We identified 445 patients with diffuse WHO grade II gliomas, including 59 IDH1/2-wildtype tumors. IDH-wildtype grade II gliomas affected more frequently male (75% vs. 55%, p = 0.004) and older (mean age: 50.0 vs. 39.6 years, p<0.0001) patients, had frequent fronto-temporo-insular location (41%) and commonly underwent biopsy (53%) rather than resection. We found TERT promoter mutations (18/42, 43%), chromosome 7q gains (12/30, 40%), chromosome 10q losses (12/44, 27%), chromosome 9p losses (7/47, 15%), EGFR amplifications (5/51, 10%) and p16 deletions (4/50, 8%) but no P53 (0/16) mutations. Median overall survival was 46 months (vs. 98 for IDH-mutant non codeleted and 175 for IDH-mutant codeleted WHO grade II gliomas (p<0.0001); vs. 20 months for IDH-wildtype WHO grade III gliomas (p = 0.001)). Survival was not significantly influenced by age, preoperative KPS, tumor location, extent of resection or adjuvant treatment schemes. Chromosome 9p loss had a strong negative impact on overall survival (p=0.002). CONCLUSION The median overall survival associated with IDH-wildtype WHO grade II gliomas does not exceed 4 years from diagnosis. As some genetic alterations seem to have a strong prognostic impact, an exhaustive genetic assessment can be helpful in this rare tumor group for purposes of prognostic stratification and treatment decision.