Clonal lineage of high grade serous ovarian cancer in a patient with neurofibromatosis type 1

Survey of NF1 inactivation by surrogate immunohistochemistry in ovarian carcinomas

OBJECTIVE

Inhibition of the MAPK pathway by MEK inhibitors (MEKi) is currently a therapeutic standard in several cancer types, including ovarian low-grade serous carcinoma (LGSC). A common MAPK pathway alteration in tubo-ovarian high-grade serous carcinoma (HGSC) is the genomic inactivation of neurofibromin 1 (NF1). The primary objectives of our study were to survey the prevalence of NF1 inactivation in the principal ovarian carcinoma histotype as well as to evaluate its associations with clinico-pathological parameters and key biomarkers including BRCA1/2 status in HGSC.

METHODS

A recently commercialized NF1 antibody (clone NFC) was orthogonally validated on an automated immunohistochemistry (IHC) platform and IHC was performed on tissue microarrays containing 2140 ovarian carcinoma cases. Expression was interpreted as loss/inactivated (complete or subclonal) versus normal/retained.

RESULTS

Loss of NF1 expression was detected in 250/1429 (17.4%) HGSC including 11% with subclonal loss. Survival of NF1-inactivated HGSC patients was intermediate between favorable BRCA1/2 mutated HGSC and unfavorable CCNE1 high-level amplified HGSC. NF1 inactivation was mutually exclusive with CCNE1 high-level amplifications, co-occurred with RB1 loss and occurred at similar frequencies in BRCA1/2 mutated versus wild-type HGSC. NF1 loss was found in 21/286 (7.3%) endometrioid carcinomas with a favorable prognostic association (p = 0.048), and in 4/64 (5.9%) LGSC, mutually exclusive with other driver events.

CONCLUSIONS

NF1 inactivation occurs in a significant subset of BRCA1/2 wild-type HGSC and a subset of LGSC. While the functional effects of NF1 inactivation need to be further characterized, this signifies a potential therapeutic opportunity to explore targeting NF1 inactivation in these tumors.

Targeting RAS-ERK pathway alterations with MEK inhibitors to improve chemosensitivity in high grade serous ovarian cancers

OBJECTIVE

Assess if MEK inhibitor blockade of RAS-ERK pathway adaptive response in high grade serous ovarian cancers (HGSOC) improves platinum sensitivity.

METHODS

Three HGSOC cell lines and three patient derived organoid (PDOs) samples from ascites of platinum resistant HGSOC patients were collected. Cell lines and PDOs were exposed to carboplatin and MEK inhibitors cobimetinib or trametinib. Cytotoxic effects of MEK inhibitors alone or combined with carboplatin were established. Western blots demonstrated RAS-ERK pathway blockage after MEK inhibitor treatment. RNA sequencing assessed gene expression after MEK inhibitor treatment. Cell line NF1 gene knockdown was performed with corresponding chemosensitivity levels.

RESULTS

High carboplatin IC50 levels indicated platinum resistance in cell lines and PDOs. Cobimetinib induced cytotoxicity in cell lines and PDOs, while trametinib was less effective. Western blot confirmed MEK-ERK pathway blockage at minimal concentrations of MEK inhibitors in cell lines and PDOs. Phosphorylated-ERK levels of untreated cells indicated higher levels of RAS-ERK pathway activation in OVSAHO and OVCAR7 compared to OVCAR3. OVSAHO harbors a NF1 mutation and had highest levels of RAS-ERK activation. Cotreatment with carboplatin and MEK inhibitors showed varying synergistic cytotoxic effects at different combinations. Synergistic effect was most prominent in the OVSAHO carboplatin and cobimetinib combination. RNA sequencing identified downregulation of c-MYC and FOXM1 gene expression after MEK inhibitor treatment. NF1 gene knockdown showed an acquired increased IC50 compared to parental cells.

CONCLUSION

MEK inhibitors block RAS-ERK pathways in platinum resistant HGSOC cells and PDOs. MEK inhibitors with carboplatin have select synergistic effects which may indicate a strategy to improve platinum sensitivity.

PLK3 amplification and tumor immune microenvironment of metastatic tumors are linked to adjuvant treatment outcomes in uterine serous cancer

Uterine serous carcinoma (USC), an aggressive variant of endometrial cancer representing approximately 10% of endometrial cancer diagnoses, accounts for ∼39% of endometrial cancer-related deaths. We examined the role of genomic alterations in advanced-stage USC associated with outcome using paired primary-metastatic tumors (n = 29) treated with adjuvant platinum and taxane chemotherapy. Comparative genomic analysis of paired primary-metastatic patient tumors included whole exome sequencing and targeted gene expression. Both PLK3 amplification and the tumor immune microenvironment (TIME) in metastatic tumors were linked to time-to-recurrence (TTR) risk without any such association observed with primary tumors. TP53 loss was significantly more frequent in metastatic tumors of platinum-resistant versus platinum-sensitive patients and was also associated with increased recurrence and mortality risk. Increased levels of chr1 breakpoints in USC metastatic versus primary tumors co-occur with PLK3 amplification. PLK3 and the TIME are potential targets for improving outcomes in USC adjuvant therapy.

Mutation spectrum of the NF1 gene and genotype-phenotype correlations in Turkish patients: Seventeen novel pathogenic variants

OBJECTIVE

Neurofibromatosis type 1 is one of the most common autosomal dominant diseases caused by heterozygous mutation in the NF1 gene. Wide spectrum of NF1-related clinical manifestations and mutation distribution makes genetic counselling difficult.

METHODS

The study enrolled 58 unrelated Turkish patients with clinically suspected NF1 referred to the Department of Medical Genetics. Individuals were eligible if they 1) met at least two of the main National Institutes of Health criteria or 2) had multiple café-au-lait macules as a child.

RESULTS

Fourty-one different disease-causing variants were identified in 42 (72.4%) individuals, including 17 novel variants. Twenty-four (58.2%) of the NF1 patients had de novo variants. Café-au-lait macules were observed in all patients (100%). Intracranial hamartoma was the second most common phenotype, found in 52.3% (22/42) of the patients. Other common manifestations were neurofibromas (35.7%), axillary or inguinal freckling (28.5%), and Lisch nodules (28.5%). Additionally, one patient had intra-abdominal malignant peripheral nerve sheath tumours and another patient underwent surgery for serous papillary ovarian cancer.

CONCLUSION

In conclusion, this study is one of the largest studies from Turkey to investigate the NF1 mutation spectrum and genotype-phenotype correlations.

Biallelic NF1 inactivation in high grade serous ovarian cancers from patients with neurofibromatosis type 1

Neurofibromatosis type 1 (NF1) is a multisystem disorder caused by germline heterozygous NF1 loss-of-function variants. The NF1 gene encodes neurofibromin, a RAS GTPase-activating protein, which functions by down-regulating RAS/RAF/MAPK-signalling pathways. Somatic NF1 aberrations frequently occur in sporadic ovarian cancer (OC), but the incidence of OC in NF1 patients is rare. Here we report the germline and somatic findings for two unrelated patients with NF1 and high-grade serous OC. Germline testing revealed a heterozygous NF1 pathogenic variant in each patient, c.7096_7101del (p.Asn2366_Phe2367del) and c.964delA (p.Ile322Leufs*54), respectively. No germline variants in well-established OC predisposition genes were detected, including BRCA1 and BRCA2. Tumor loss-of-heterozygosity analysis demonstrated loss of the wild type NF1 allele for both patients. Biallelic NF1 inactivation occurs as part of OC pathogenesis in NF1 patients. Although the penetrance of NF1-associated OC is insufficient to warrant risk-reducing interventions, our findings highlight the potential for therapies targeting the RAS/RAF/MAPK-signalling pathway for these cases.

Appendiceal neurofibroma in a patient with neurofibromatosis 1 and recurrent abdominal infections from ventriculoperitoneal shunt: a case report

Appendiceal neurofibromas are exceedingly rare, with neither experimental nor observational data to support evidence-based diagnosis or treatment. We describe the case of a 52-year-old woman with neurofibromatosis 1 (NF1) complicated by aqueductal stenosis and resultant hydrocephalus needing a ventriculoperitoneal shunt (VPS). She presented to the emergency department with abdominal pain and was found to have abnormalities in the right hemiabdomen on cross-section imaging, also a Staphylococcus epidermidis growth at the distal portion of the VPS. She was initially treated with two rounds of intravenous antibiotics and VPS removal without improvement. She ultimately underwent an appendectomy, which revealed pathologic evidence of NF. The appendectomy was key to ruling out malignancy, addressing further symptoms and preventing future malignant transformation. This case highlights the importance of including appendiceal neurofibromas in the differential diagnoses of abdominal pain in patients with NF1.

Imaging Features of Neurofibromatosis Type 1 in the Abdomen and Pelvis

OBJECTIVE. Loss of the neurofibromatosis type 1 (NF1) tumor suppressor protein causes uninhibited activation of the RAS oncogene, which leads to tumorigenesis in patients with NF1. This case-based review discusses imaging manifestations of NF1 in the abdomen and pelvis, highlighting key genetic associations and management to elucidate features different from the general population. CONCLUSION. The spectrum of pathologic findings includes gastrointestinal tumors such as gastrointestinal stromal tumors, genitourinary lesions including urogenital neurofibromas, vascular entities such as renal artery stenosis, and less common associations like lymphoma.

Molecular Analysis of Clinically Defined Subsets of High-Grade Serous Ovarian Cancer

The diversity and heterogeneity within high-grade serous ovarian cancer (HGSC), which is the most lethal gynecologic malignancy, is not well understood. Here, we perform comprehensive multi-platform omics analyses, including integrated analysis, and immune monitoring on primary and metastatic sites from highly clinically annotated HGSC samples based on a laparoscopic triage algorithm from patients who underwent complete gross resection (R0) or received neoadjuvant chemotherapy (NACT) with excellent or poor response. We identify significant distinct molecular abnormalities and cellular changes and immune cell repertoire alterations between the groups, including a higher rate of NF1 copy number loss, and reduced chromothripsis-like patterns, higher levels of strong-binding neoantigens, and a higher number of infiltrated T cells in the R0 versus the NACT groups.

Acromegaly caused by a somatotroph adenoma in patient with neurofibromatosis type 1

Although acromegaly has been reported in patients with Neurofibromatosis type 1 (NF1), these cases have not been associated with growth hormone (GH)-producing somatotroph adenoma, but with optic pathway glioma. A 68 year-old Japanese woman, who had been clinically diagnosed with NF1, was referred to our hospital due to a thyroid tumor and hypercalcemia. Acromegaly was suspected due to her facial features, and subsequent examinations revealed the presence of GH excess with a pituitary tumor, leading to the diagnosis of acromegaly. Histological and immunohistochemical analysis demonstrated an eosinophilic pituitary adenoma with diffuse positivity for GH, indicating typical somatotroph adenoma. In addition, her thyroid tumor was diagnosed histologically as follicular thyroid carcinoma (FTC) with primary hyperparathyroidism (PHPT). To investigate the pathogenesis of this untypical multiple endocrine tumor case of NF1, genetic analysis was performed using peripheral leukocytes and tissue of resected tumors. A heterozygous novel germline nonsense mutation (p.Arg1534*) in exon 35 of the NF1 gene was detected from peripheral leukocytes, which results in a truncated protein lacking the critical domain for GTPase activity, strongly suggesting its causal role in NF1. The loss of heterozygosity (LOH) in exon 35 of the NF1 gene was not detected in the somatotroph adenoma, parathyroid adenoma, and FTC. Although any mutations of the following genes; MEN1, CDKN1B, and PAX8-PPARγ were not detected, a heterozygous GNAS R201C mutation was detected in the somatotroph adenoma. To our knowledge, this is the first rare MEN1-like case of genetically diagnosed NF1 complicated with acromegaly caused by a somatotroph adenoma.