Increased prevalence of germline pathogenic CHEK2 variants in individuals with pituitary adenomas.

CONTEXT: CHEK2 is a cell cycle checkpoint regulator gene with a long-established role as a clinically relevant, moderate risk breast cancer predisposition gene, with greater risk ascribed to truncating variants than missense variants. METHODS: We assessed 165 individuals with pituitary adenomas for CHEK2 variants. The study consisted of a primary cohort of 29 individuals who underwent germline and tumour whole exome sequencing, and a second, independent cohort of 136 individuals who had a targeted next-generation sequencing panel performed on both germline and tumour DNA (n=52) or germline DNA alone (n=84). RESULTS: We identified rare, coding, non-synonymous germline CHEK2 variants amongst 3/29 (10.3%) patients in our primary cohort and 5/165 (3.0%) patients overall, with affected patients having a range of hormone secretion types (prolactinoma, thyrotrophinoma, somatotrophinoma and non-functioning pituitary adenoma). No somatic variants were identified. Two variants were definitive null variants (c.1100delC, c.444+1G>A), classified as pathogenic. Two variants were missense variants (p.Asn186His, p.Thr476Met), classified as likely pathogenic. Even when considering the null variants only, the rate of CHEK2 variants was higher in our cohort compared to national control data (1.8% vs. 0.5%, P=0.049). CONCLUSIONS: This is the first study to suggest a role for the breast cancer predisposition gene, CHEK2, in pituitary tumorigenesis, with pathogenic/likely pathogenic variants found in 3% of patients with pituitary adenomas. As pituitary adenomas are relatively common and typically lack classical autosomal dominant family histories, risk alleles - such as these variants found in CHEK2 - might be a significant contributor to pituitary adenoma risk in the general population.

Impact of semaglutide and dulaglutide shortages on Pharmaceutical Benefits Scheme prescriptions supplied for type 2 diabetes treatment.

METHOD: A retrospective analysis was performed of actual and predicted (Holt-Winters modelling) semaglutide and dulaglutide prescriptions supplied by the Australian PBS and Repatriation PBS in 2021-22. RESULTS: Semaglutide prescriptions decreased by 17% in March - September 2022, whereas dulaglutide prescriptions increased by 53% in April - July 2022 before decreasing by 17% in August - September 2022. There were 119,069 fewer semaglutide and 31,953 more dulaglutide prescriptions supplied than predicted in April - July and June - July 2022, respectively. DISCUSSION: Changes in semaglutide and dulaglutide T2D prescription patterns in 2022 coincided with supply shortages. General practitioners are encouraged to continue to prescribe semaglutide and dulaglutide for their appropriate indication and support patients with alternative treatments during the shortage.

PAM variants in patients with thyrotrophinomas, cyclical Cushing's disease and prolactinomas.

Introduction: Germline loss-of-function variants in PAM, encoding peptidylglycine α-amidating monooxygenase (PAM), were recently discovered to be enriched in conditions of pathological pituitary hypersecretion, specifically: somatotrophinoma, corticotrophinoma, and prolactinoma. PAM is the sole enzyme responsible for C-terminal amidation of peptides, and plays a role in the biosynthesis and regulation of multiple hormones, including proopiomelanocortin (POMC). Methods: We performed exome sequencing of germline and tumour DNA from 29 individuals with functioning pituitary adenomas (12 prolactinomas, 10 thyrotrophinomas, 7 cyclical Cushing's disease). An unfiltered analysis was undertaken of all PAM variants with population prevalence <5%. Results: We identified five coding, non-synonymous PAM variants of interest amongst seven individuals (six germline, one somatic). The five variants comprised four missense variants and one truncating variant, all heterozygous. Each variant had some evidence of pathogenicity based on population prevalence, conservation scores, in silico predictions and/or prior functional studies. The yield of predicted deleterious PAM variants was thus 7/29 (24%). The variants predominated in individuals with thyrotrophinomas (4/10, 40%) and cyclical Cushing's disease (2/7, 29%), compared to prolactinomas (1/12, 8%). Conclusion: This is the second study to demonstrate a high yield of suspected loss-of-function, predominantly germline, PAM variants in individuals with pathological pituitary hypersecretion. We have extended the association with corticotrophinoma to include the specific clinical entity of cyclical Cushing's disease and demonstrated a novel association between PAM variants and thyrotrophinoma. PAM variants might act as risk alleles for pituitary adenoma formation, with a possible genotype-phenotype relationship between truncating variants and altered temporal secretion of cortisol.

Insights into pituitary tumorigenesis: from Sanger sequencing to next-generation sequencing and beyond.

Introduction: This review explores insights provided by next-generation sequencing (NGS) of pituitary tumors and the clinical implications.Areas covered: Although syndromic forms account for just 5% of pituitary tumours, past Sanger sequencing studies pragmatically focused on them. These studies identified mutations in MEN1, CDKN1B, PRKAR1A, GNAS and SDHx causing Multiple Endocrine Neoplasia-1 (MEN1), MEN4, Carney Complex-1, McCune Albright Syndrome and 3P association syndromes, respectively. Furthermore, linkage analysis of single-nucleotide polymorphisms identified AIP mutations in 20% with familial isolated pituitary adenomas (FIPA). NGS has enabled further investigation of sporadic tumours. Thus, mutations of USP8 and CABLES1 were identified in corticotrophinomas, BRAF in papillary craniopharyngiomas and CTNNB1 in adamantinomatous craniopharyngiomas. NGS also revealed that pituitary tumours occur in the DICER1 syndrome, due to DICER1 mutations, and CDH23 mutations occur in FIPA. These discoveries revealed novel therapeutic targets and studies are underway of BRAF inhibitors for papillary craniopharyngiomas, and EGFR and USP8 inhibitors for corticotrophinomas.Expert opinion: It has become apparent that single-nucleotide variants and small insertion/deletion DNA mutations cannot explain all pituitary tumorigenesis. Integrated and improved analyses including whole-genome sequencing, copy number, and structural variation analyses, RNA sequencing and epigenomic analyses, with improved genomic technologies, are likely to further define the genomic landscape.

The Genomic Landscape of Sporadic Prolactinomas.

Somatic GNAS and USP8 mutations have been implicated in sporadic somatotrophinomas and corticotrophinomas, respectively. However, no genes are known to be recurrently mutated in sporadic prolactinomas. The prevalence of copy number variants (CNV), which is emerging as a mechanism of tumorigenesis in sporadic pituitary adenomas in general, is also unclear in prolactinomas. To characterize the genetic events underpinning sporadic prolactinomas, we performed whole exome sequencing of paired tumor and germline DNA from 12 prolactinoma patients. We observed recurrent large-scale CNV, most commonly in the form of copy number gains. We also identified sequence variants of interest in 15 genes. This included the DRD2, PRL, TMEM67, and MLH3 genes with plausible links to prolactinoma formation. Of the 15 genes of interest, CNV was seen at the gene locus in the corresponding tumor in 10 cases, and pituitary expression of eight genes was in the top 10% of tissues. However, none of our shortlisted somatic variants appeared to be classical driver mutations as no variant was found in more than one tumor. Future directions of research include mechanistic studies to investigate how CNV may contribute to prolactinoma formation, larger studies of relevant prolactinoma subsets according to clinical characteristics, and additional genetic investigations for aberrations not captured by whole exome sequencing.

Histological and Extended Clinical Outcomes After ABO-Incompatible Renal Transplantation Without Splenectomy or Rituximab.

BACKGROUND: Excellent short-term results have been reported in ABO-incompatible (ABOi) renal transplant recipients managed solely with antibody removal and conventional immunosuppression. However, long-term clinical outcomes with this regimen and predictive information from protocol biopsies are lacking. METHODS: We compared outcome data in ABOi and ABO-compatible (ABOc) recipients receiving this regimen approximately 4 years posttransplant, and histology from biopsies approximately 12 months posttransplant. RESULTS: Patient and graft survivals among 54 ABOi recipients were 98.1% and 90.7%, respectively, at 4 years. Graft function was similar between ABOi (creatinine, 140.3 µmol/L) and ABOc recipients (creatinine, 140.2 µmol/L) (P = 0.99), with no significant change over the study period in either group (Δcreatinine, -0.83 vs 6.6 µmol/L) (P = 0.59). There was no transplant glomerulopathy in biopsies from either group. Interstitial fibrosis (IF) and tubular atrophy (TA) was present in 7 (28%) of 25 ABOi compared with 7 (20.6%) of 34 ABOc (P = 0.52). Progression of IF/TA from implantation was noted in 6 (24%) of 25 ABOi and 6 (17.6%) of 34 ABOc, respectively. C4d staining without antibody-mediated rejection was present in 13 (52%) 25 early posttransplant biopsies from ABOi recipients by immunohistochemistry, but in only 4 (16%) of 25 at 12 months. CONCLUSIONS: ABO-incompatible renal transplant performed with antibody removal and conventional immunosuppression continues to provide excellent patient and graft survival, and stable renal function over 4 years. Coupled with absent transplant glomerulopathy and low rates of progressive IF/TA on earlier biopsies, this suggests that ABOi with conventional immunosuppression and antibody removal, without rituximab or splenectomy, can achieve long-term outcomes comparable to ABO-compatible transplantation.