SDHA related phaeochromocytoma and paraganglioma: review and clinical management.

Phaeochromocytomas and paragangliomas (collectively termed PPGLs) are rare yet highly heritable neuroendocrine tumours, with over one third of cases associated with germline pathogenic variants (PVs) in numerous genes. PVs in succinate dehydrogenase subunit-A gene (SDHA) were initially implicated in hereditary PPGL in 2010 and SDHA has since become an important susceptibility gene accounting for up to 2.8 % of cases. However, it remains poorly understood, particularly regarding the clinical nature of SDHA PPGL, rates of recurrence and metastasis, and nature of metastatic disease. We present a narrative review of SDHA-related PPGL, covering pathophysiology, relevance to current clinical practice, and considerations for clinical genetics. We analyse a pool of 107 previously reported cases of SDHA-associated PPGL to highlight the spectrum of SDHA-related PPGL. Our analysis demonstrates SDHA PPGL occurs across a wide age-range (11-81 y) and affects men and women equally. SDHA PPGL typically present as single tumours (91%), usually occurring in the head and neck (46%) or abdomen (43%, including 15% with phaeochromocytomas). Metastatic disease was reported in 25.5% cases with bone (82%) and lymph nodes (71%) being the most common sites of metastasis, often identified many years after initial diagnosis. Family history of SDHA-related neoplasia was rare, reported in only 4% of cases. Understanding the clinical nature and risks associated with SDHA PVs is essential for facilitating optimal management of patients and their families.

Anaplastic thyroid cancer: A review of recent evidence and summary of an Australian institutional protocol.

Anaplastic thyroid cancer (ATC), a rare and highly aggressive malignancy, is characterized by an exceptionally poor prognosis, where the majority of patients present with extensive local invasion and/or distant metastases. 20-30% of ATCs harbor the BRAF-V600E mutation. Neoadjuvant BRAF-targeted therapy may have the potential to downstage and facilitate surgical resection for patients with locally advanced and unresectable primary tumors with BRAF mutation and may convey a survival advantage in those with metastatic disease. There is emerging evidence to support the use of other targeted agents, including multikinase inhibitors, as well as the incorporation of immunotherapy into the treatment regimen. Rapid molecular and pathological diagnosis and expert multidisciplinary discussion at specialized treatment centers are critical to expedite investigations and initiate treatment for this complex and rapidly progressive disease.

Study protocol for the ROLEX-DUO randomised placebo-controlled trial: ROmosozumab Loaded with EXercise - DUal effects on bone and muscle in postmenopausal Osteoporosis and Osteopenia.

INTRODUCTION: Novel strategies are needed to address the rising burden of osteoporosis and fragility fractures. High-intensity resistance and impact (HiRIT) exercise has shown benefit in improving bone density in postmenopausal women with osteoporosis/osteopenia. Whether HiRIT can enhance the therapeutic effects of osteoporosis pharmacotherapy has not been established. ROLEX-DUO is a randomised controlled trial designed to assess the efficacy of romosozumab on various bone and muscle outcomes in combination with different exercise interventions in women with postmenopausal osteoporosis/osteopenia. METHODS AND ANALYSIS: ROLEX-DUO is an 8-month randomised placebo-controlled trial conducted at two tertiary referral centres for patients with osteoporosis/osteopenia in Sydney, New South Wales, Australia. The study is implementing the combination of romosozumab or placebo with different forms of exercise in postmenopausal women with osteoporosis/osteopenia without recent fragility fracture (n=102). Eligible women will be randomised 1:1:1 into one of three groups: (1) romosozumab with supervised HiRIT, (2) romosozumab with unsupervised low-intensity exercise or (3) placebo with unsupervised low-intensity exercise. Co-primary outcomes are the mean percentage change in lumbar spine bone mineral density (BMD), and mean change in five times sit-to-stand test performance (seconds) at 8 months. Secondary/exploratory outcomes include BMD changes at the femoral neck, total hip and distal radius, three-dimensional dual-energy X-ray absorptiometry (DXA) hip outcomes, DXA-derived lean and fat mass, serum markers of bone turnover (procollagen type 1 peptide, C-telopeptide of type 1 collagen) and bone biomarkers (dickkopf-1), serum extracellular vesicle analyses, 36-Item Short Form Survey (SF-36) quality-of-life scores, Menopause-Specific Quality Of Life (MENQOL) Questionnaire menopause symptom burden scores, number of falls and fractures. Mixed-effects models will be performed to compare longitudinal outcome results between groups using intention-to-treat analysis. ETHICS AND DISSEMINATION: The trial was approved by the Northern Sydney Local Health District Human Research Ethics Committee (2022/ETH01794, protocol V.8, dated 03 July 2024). Participants will provide written informed consent prior to inclusion. Findings will be disseminated via peer-reviewed journals, scientific conferences and summary reports to funding bodies. TRIAL REGISTRATION NUMBER: ACTRN12623000867695.

SUMO promotes DNA repair protein collaboration to support alternative telomere lengthening in the absence of PML.

The alternative lengthening of telomeres (ALT) pathway maintains telomere length in a significant fraction of cancers that are associated with poor clinical outcomes. A better understanding of ALT mechanisms is therefore necessary for developing new treatment strategies for ALT cancers. SUMO modification of telomere proteins contributes to the formation of ALT telomere-associated PML bodies (APBs), in which telomeres are clustered and DNA repair proteins are enriched to promote homology-directed telomere DNA synthesis in ALT. However, it is still unknown whether-and if so, how-SUMO supports ALT beyond APB formation. Here, we show that SUMO condensates that contain DNA repair proteins enable telomere maintenance in the absence of APBs. In PML knockout ALT cell lines that lack APBs, we found that SUMOylation is required for manifesting ALT features independent of PML and APBs. Chemically induced telomere targeting of SUMO produces condensate formation and ALT features in PML-null cells. This effect requires both SUMOylation and interactions between SUMO and SUMO interaction motifs (SIMs). Mechanistically, SUMO-induced effects are associated with the accumulation of DNA repair proteins, including Rad52, Rad51AP1, RPA, and BLM, at telomeres. Furthermore, Rad52 can undergo phase separation, enrich SUMO at telomeres, and promote telomere DNA synthesis in collaboration with the BLM helicase in a SUMO-dependent manner. Collectively, our findings suggest that SUMO condensate formation promotes collaboration among DNA repair factors to support ALT telomere maintenance without PML. Given the promising effects of SUMOylation inhibitors in cancer treatment, our findings suggest their potential use in perturbing telomere maintenance in ALT cancer cells.

Megalin Knockout Reduces SGLT2 Expression and Sensitizes to Western Diet-induced Kidney Injury.

Megalin (Lrp2) is a multiligand receptor that drives endocytic flux in the kidney proximal tubule (PT) and is necessary for the recovery of albumin and other filtered proteins that escape the glomerular filtration barrier. Studies in our lab have shown that knockout (KO) of Lrp2 in opossum PT cells leads to a dramatic reduction in sodium-glucose co-transporter 2 (SGLT2) transcript and protein levels, as well as differential expression of genes involved in mitochondrial and metabolic function. SGLT2 transcript levels are reduced more modestly in Lrp2 KO mice. Here, we investigated the effects of Lrp2 KO on kidney function and health in mice fed regular chow (RC) or a Western-style diet (WD) high in fat and refined sugar. Despite a modest reduction in SGLT2 expression, Lrp2 KO mice on either diet showed increased glucose tolerance compared to control mice. Moreover, Lrp2 KO mice were protected against WD-induced fat gain. Surprisingly, renal function in male Lrp2 KO mice on WD was compromised, and the mice exhibited significant kidney injury compared with control mice on WD. Female Lrp2 KO mice were less susceptible to WD-induced kidney injury than male Lrp2 KO. Together, our findings reveal both positive and negative contributions of megalin expression to metabolic health, and highlight a megalin-mediated sex-dependent response to injury following WD.

A novel sequential treatment approach between denosumab and romosozumab in patients with severe osteoporosis.

In severe osteoporosis, the optimal approach for sequential treatment between denosumab and romosozumab is unclear. We utilised a novel overlapping strategy in three patients with very-high fracture risk despite long-term denosumab which led to greater bone density improvements than previously reported with standard approaches. Larger confirmatory prospective studies are needed. PURPOSE/INTRODUCTION: In patients with severe osteoporosis, the optimal approach for sequential treatment between denosumab and romosozumab has not been established. The ideal strategy would maximise gains in bone mineral density (BMD) with romosozumab and effectively mitigate the risk of rebound increased bone turnover when sequencing from denosumab. Limited studies exploring the sequence from denosumab to romosozumab report only modest-to-no improvement in BMD and inadequate suppression of rebound bone turnover. METHODS: We describe three patients with severe osteoporosis and multiple fragility fractures despite long-term denosumab. A novel overlapping sequential treatment approach was utilised to maximise therapeutic benefit given these patients had a very high fracture risk. Romosozumab was commenced 3 months after the last denosumab dose. Instead of waiting until completion of romosozumab, denosumab was recommenced 6 months after commencing romosozumab in response to rising bone turnover markers. RESULTS: Patients experienced a ~ 5-22% increase in lumbar spine BMD, and one patient had an 8% increase in total hip BMD after 12 months romosozumab. Serum bone turnover markers demonstrated an anabolic effect of romosozumab occurred despite overlapping treatment with denosumab. Recommencement of denosumab suppressed an increase in bone resorption in all cases. No new vertebral fractures occurred during this treatment. CONCLUSIONS: A novel overlapping sequential treatment approach between denosumab and romosozumab produced greater improvements in lumbar spine and hip BMD than previously reported with standard approaches. Larger prospective controlled studies are needed to confirm these findings and establish the optimal use of romosozumab in patients pre-treated with denosumab to maximise BMD gains and minimise fracture risk.

Large variance in a lateral osteoarthritic population prior to and following lateral unicompartmental arthroplasty: An analysis of knee phenotypes.

BACKGROUND: Disagreement exists on the optimal coronal alignment target for lateral unicompartmental knee arthroplasty (UKA). An improved understanding of the distribution of coronal alignment and joint line orientation in lateral osteoarthritis (OA) might prove beneficial. The aim of this study was to evaluate the pre- and postoperative Coronal Plane Alignment of the Knee (CPAK) distribution following lateral UKA and to evaluate the association between phenotypic variation and patient-reported outcome measures (PROMs). METHODS: A surgeon's registry was retrospectively reviewed between 2012 and 2022 to identify patients who received primary lateral UKA for advanced, lateral compartment OA. Radiographic measurements were performed, and CPAK phenotypes were determined. The Knee Injury and Osteoarthritis Outcome Score (KOOS), Kujala, and patient satisfaction were analyzed at one-year and two-year follow-up. RESULTS: A total of 305 knees were included. Preoperatively, seven phenotypes were observed and CPAK3 (54.1%) was most commonly observed. Postoperatively, all nine phenotypes were observed and CPAK6 (32.8%) was predominant. Preoperatively, 23.6% did not have a prearthritic valgus alignment. No significant differences in PROMs were found between individual phenotypes or between preserved and altered phenotypes. CONCLUSION: Coronal alignment and joint line orientation were highly variable within a lateral compartment OA cohort. However, no association was demonstrated between superior postoperative PROMs and phenotype variation or phenotype preservation, which might suggest that there is not one universal optimal alignment target. Interestingly, 23.6% of knees with lateral compartment OA did not have a prearthritic valgus alignment, which may have been affected by joint line orientation.

Eumycetoma causative agents: A systematic review to inform the World Health Organization priority list of fungal pathogens.

The World Health Organization, in response to the growing burden of fungal disease, established a process to develop a fungal priority pathogens list. This systematic review aimed to evaluate the epidemiology and impact of eumycetoma. PubMed and Web of Science were searched to identify studies published between 1 January 2011 and 19 February 2021. Studies reporting on mortality, inpatient care, complications and sequelae, antifungal susceptibility, risk factors, preventability, annual incidence, global distribution, and emergence during the study time frames were selected. Overall, 14 studies were eligible for inclusion. Morbidity was frequent with moderate to severe impairment of quality of life in 60.3%, amputation in up to 38.5%, and recurrent or long-term disease in 31.8%-73.5% of patients. Potential risk factors included male gender (56.6%-79.6%), younger age (11-30 years; 64%), and farming occupation (62.1%-69.7%). Mycetoma was predominantly reported in Sudan, particularly in central Sudan (37%-76.6% of cases). An annual incidence of 0.1/100 000 persons and 0.32/100 000 persons/decade was reported in the Philippines and Uganda, respectively. In Uganda, a decline in incidence from 3.37 to 0.32/100 000 persons between two consecutive 10-year periods (2000-2009 and 2010-2019) was detected. A community-based, multi-pronged prevention programme was associated with a reduction in amputation rates from 62.8% to 11.9%. With the pre-specified criteria, no studies of antifungal drug susceptibility, mortality, and hospital lengths of stay were identified. Future research should include larger cohort studies, greater drug susceptibility testing, and global surveillance to develop evidence-based treatment guidelines and to determine more accurately the incidence and trends over time.

Heme-induced loss of renovascular endothelial protein C receptor promotes chronic kidney disease in sickle mice.

ABSTRACT: Chronic kidney disease (CKD) is a major contributor to morbidity and mortality in sickle cell disease (SCD). Anemia, induced by chronic persistent hemolysis, is associated with the progressive deterioration of renal health, resulting in CKD. Moreover, patients with SCD experience acute kidney injury (AKI), a risk factor for CKD, often during vaso-occlusive crisis associated with acute intravascular hemolysis. However, the mechanisms of hemolysis-driven pathogenesis of the AKI-to-CKD transition in SCD remain elusive. Here, we investigated the role of increased renovascular rarefaction and the resulting substantial loss of the vascular endothelial protein C receptor (EPCR) in the progressive deterioration of renal function in transgenic SCD mice. Multiple hemolytic events raised circulating levels of soluble EPCR (sEPCR), indicating loss of EPCR from the cell surface. Using bone marrow transplantation and super-resolution ultrasound imaging, we demonstrated that SCD mice overexpressing EPCR were protective against heme-induced CKD development. In a cohort of patients with SCD, plasma sEPCR was significantly higher in individuals with CKD than in those without CKD. This study concludes that multiple hemolytic events may trigger CKD in SCD through the gradual loss of renovascular EPCR. Thus, the restoration of EPCR may be a therapeutic target, and plasma sEPCR can be developed as a prognostic marker for sickle CKD.

Podocyte-Specific Deletion of MCP-1 Fails to Protect against Angiotensin II- or Adriamycin-Induced Glomerular Disease.

Investigating the role of podocytes in proteinuric disease is imperative to address the increasing global burden of chronic kidney disease (CKD). Studies strongly implicate increased levels of monocyte chemoattractant protein-1 (MCP-1/CCL2) in proteinuric CKD. Since podocytes express the receptor for MCP-1 (i.e., CCR2), we hypothesized that podocyte-specific MCP-1 production in response to stimuli could activate its receptor in an autocrine manner, leading to further podocyte injury. To test this hypothesis, we generated podocyte-specific MCP-1 knockout mice (Podo-Mcp-1fl/fl) and exposed them to proteinuric injury induced by either angiotensin II (Ang II; 1.5 mg/kg/d, osmotic minipump) or Adriamycin (Adr; 18 mg/kg, intravenous bolus). At baseline, there were no between-group differences in body weight, histology, albuminuria, and podocyte markers. After 28 days, there were no between-group differences in survival, change in body weight, albuminuria, kidney function, glomerular injury, and tubulointerstitial fibrosis. The lack of protection in the knockout mice suggests that podocyte-specific MCP-1 production is not a major contributor to either Ang II- or Adr-induced glomerular disease, implicating that another cell type is the source of pathogenic MCP-1 production in CKD.

Preservation of prearthritic coronal knee phenotype and prearthritic coronal alignment yielded improved Kujala scores following ligament-guided medial unicompartmental knee arthroplasty.

PURPOSE: There is a lack of literature evaluating outcomes of the ligament-guided approach in medial unicompartmental knee arthroplasty (UKA). An improved comprehension of the distribution of coronal plane alignment of the knee (CPAK) phenotypes and sagittal tibial wear patterns and their associations with patient-reported outcome measures (PROMs) and implant survivorship could provide insights into its further application in daily practice. METHODS: A registry was reviewed for patients with a minimal 2-year follow-up who underwent robotic-assisted, ligament-guided, medial UKA between 2008 and 2016. Survivorship and postoperative PROMs were collected. CPAK phenotypes and sagittal tibial wear patterns were determined. Survivorship, Knee Injury and Osteoarthritis Outcome Score (KOOS), Kujala and patient satisfaction were compared between phenotypes and sagittal tibial wear patterns. RESULTS: A total of 618 knees were included at a mean follow-up of 4.1 [2.0-9.6] years. Four-year conversion to the TKA survival rate was 98.9% [98.4%-99.3%] and 94.3% [93.3%-95.3%] for all-cause revision. Patients with preservation of the CPAK phenotype (84.5 ± 14.9, 81.8 ± 15.5, p = 0.033) and restoration of prearthritic coronal alignment (84.1 ± 14.9, 81.7 ± 15.9, p = 0.045) had a significantly higher Kujala score. No other significant differences in survivorship or PROMs were observed between phenotypes or sagittal tibial wear patterns. Additionally, no difference in survival rates was observed between preserved or altered phenotypes. CONCLUSION: This study demonstrated that preservation of CPAK phenotype and preservation of prearthritic coronal alignment yielded a significantly higher Kujala score. No other significant differences in PROMs or implant survivorship were observed, suggesting that robotic-assisted, ligament-guided medial UKA provides equal outcomes for all observed phenotypes and sagittal tibial wear patterns in medial compartment OA as long as preoperative CPAK phenotype is preserved postoperatively. LEVEL OF EVIDENCE: Level III.

Extrachromosomal telomere DNA derived from excessive strand displacements.

Alternative lengthening of telomeres (ALT) is a telomere maintenance mechanism mediated by break-induced replication, evident in approximately 15% of human cancers. A characteristic feature of ALT cancers is the presence of C-circles, circular single-stranded telomeric DNAs composed of C-rich sequences. Despite the fact that extrachromosomal C-rich single-stranded DNAs (ssDNAs), including C-circles, are unique to ALT cells, their generation process remains undefined. Here, we introduce a method to detect single-stranded telomeric DNA, called 4SET (Strand-Specific Southern-blot for Single-stranded Extrachromosomal Telomeres) assay. Utilizing 4SET, we are able to capture C-rich single-stranded DNAs that are near 200 to 1500 nucleotides in size. Both linear C-rich ssDNAs and C-circles are abundant in the fractions of cytoplasm and nucleoplasm, which supports the idea that linear and circular C-rich ssDNAs are generated concurrently. We also found that C-rich ssDNAs originate during Okazaki fragment processing during lagging strand DNA synthesis. The generation of C-rich ssDNA requires CST-PP (CTC1/STN1/TEN1-PRIMASE-Polymerase alpha) complex-mediated priming of the C-strand DNA synthesis and subsequent excessive strand displacement of the C-rich strand mediated by the DNA Polymerase delta and the BLM helicase. Our work proposes a model for the generation of C-rich ssDNAs and C-circles during ALT-mediated telomere elongation.

Deregulated DNA ADP-ribosylation impairs telomere replication.

The recognition that DNA can be ADP ribosylated provides an unexpected regulatory level of how ADP-ribosylation contributes to genome stability, epigenetics and immunity. Yet, it remains unknown whether DNA ADP-ribosylation (DNA-ADPr) promotes genome stability and how it is regulated. Here, we show that telomeres are subject to DNA-ADPr catalyzed by PARP1 and removed by TARG1. Mechanistically, we show that DNA-ADPr is coupled to lagging telomere DNA strand synthesis, forming at single-stranded DNA present at unligated Okazaki fragments and on the 3' single-stranded telomere overhang. Persistent DNA-linked ADPr, due to TARG1 deficiency, eventually leads to telomere shortening. Furthermore, using the bacterial DNA ADP-ribosyl-transferase toxin to modify DNA at telomeres directly, we demonstrate that unhydrolyzed DNA-linked ADP-ribose compromises telomere replication and telomere integrity. Thus, by identifying telomeres as chromosomal targets of PARP1 and TARG1-regulated DNA-ADPr, whose deregulation compromises telomere replication and integrity, our study highlights and establishes the critical importance of controlling DNA-ADPr turnover for sustained genome stability.

Outcomes of SDHB Pathogenic Variant Carriers.

CONTEXT: Carriers of germline pathogenic variants (PVs) in succinate dehydrogenase type B (SDHB) are at increased risk of developing pheochromocytomas and paragangliomas (PPGLs). Understanding their outcomes can guide recommendations for risk assessment and early detection. OBJECTIVE: We performed a systematic review and meta-analysis of the following outcomes in SDHB PV carriers: age-specific risk of developing tumors, metastatic progression, second primary tumor development, and mortality. METHODS: PubMed, MEDLINE, and EMBASE were searched. Sixteen studies met the inclusion criteria and were sorted into 4 outcome categories: age-specific penetrance, metastatic disease, risk of second tumor, and mortality. We assessed heterogeneity and performed a meta-analysis across studies using a random-effects model with the DerSimonian and Laird method. RESULTS: Penetrance of PPGLs for nonproband/nonindex SDHB PV carriers by age 20 was 4% (95% CI, 3%-6%), 11% (95% CI, 8%-15%) by age 40, 24% (95% CI, 19%-31%) by age 60%, and 35% (95% CI, 25%-47%) by age 80. The overall risk of metastatic disease for nonproband/nonindex carriers with PPGLs was 9% (95%, CI 5%-16%) per lifetime. In all affected cases (combining both proband/index and nonproband/nonindex carriers with tumors), the risk of a second tumor was 24% (95% CI, 18%-31%) and all-cause 5-year mortality was 18% (95% CI, 6%-40%). CONCLUSION: Penetrance for PPGLs in SDHB PV carriers increases linearly with age. Affected carriers are at risk of developing and dying of metastatic disease, or of developing second tumors. Lifelong surveillance is appropriate.

Clinical Activity of Selpercatinib in RET-mutant Pheochromocytoma.

INTRODUCTION: Activating RET alterations have been reported in a variety of solid tumors, including pheochromocytoma where they occur both sporadically and as part of familial multiple endocrine neoplasia type 2 (MEN2) syndromes. Selpercatinib is a first-in-class, highly selective, and potent small molecule RET kinase inhibitor that has demonstrated marked and durable anti-tumor activity in diverse RET-activated solid tumors in the LIBRETTO-001 study (NCT03157128). METHODS: We describe the first six pheochromocytoma cases treated with selpercatinib in the LIBRETTO-001 study. RESULTS: Of the six patients (one sporadic and five reported as part of MEN2 syndromes) in this case report, four had a partial response/complete response and two had stable disease per independent review committee. Treatment duration ranged from 9.2 months to more than 56.4 months. The safety profile of treatment was consistent with selpercatinib in other indications. CONCLUSION: These data support selpercatinib as an effective therapy against RET-mutant pheochromocytoma, adding to the diversity of RET-activated tumor types that may benefit from targeted RET inhibition.

TERRA-LSD1 phase separation promotes R-loop formation for telomere maintenance in ALT cancer cells.

The telomere repeat-containing RNA (TERRA) forms R-loops to promote homology-directed DNA synthesis in the alternative lengthening of telomere (ALT) pathway. Here we report that TERRA contributes to ALT via interacting with the lysine-specific demethylase 1A (LSD1 or KDM1A). We show that LSD1 localizes to ALT telomeres in a TERRA dependent manner and LSD1 function in ALT is largely independent of its demethylase activity. Instead, LSD1 promotes TERRA recruitment to ALT telomeres via RNA binding. In addition, LSD1 and TERRA undergo phase separation, driven by interactions between the RNA binding properties of LSD1 and the G-quadruplex structure of TERRA. Importantly, the formation of TERRA-LSD1 condensates enriches the R-loop stimulating protein Rad51AP1 and increases TERRA-containing R-loops at telomeres. Our findings suggest that LSD1-TERRA phase separation enhances the function of R-loop regulatory molecules for ALT telomere maintenance, providing a mechanism for how the biophysical properties of histone modification enzyme-RNA interactions impact chromatin function.