Gregory A. Clines

Vignette: A 49-year-old female with a history of chronic hypocalcemia had serum calcium concentrations that ranged between 6.4 and 8.5 mg/dL (nl, 8.6-10.3 mg/dL) with inappropriately low to low-normal parathyroid hormone (PTH) concentrations. She did not report symptoms of hypocalcemia. A thyroid nodule was discovered, and the patient underwent total thyroidectomy for papillary thyroid cancer. Parathyroid autotransplantation was not performed since parathyroid glands were not identified during the surgery. After total thyroidectomy, the patient developed a more severe symptomatic, refractory hypocalcemia with undetectable PTH concentrations. Postoperative pathologic examination identified a single hypercellular parathyroid gland. Despite medical treatment, including frequent and regular calcium gluconate infusions, serum calcium concentrations remained persistently low. A genetic evaluation identified a pathogenic GNA11 variant (c.178C>T, p.Arg60Cys), consistent with autosomal dominant hypocalcemia type 2 (ADH2). This case expands the understanding of ADH2 and raises important questions about optimal treatment strategies in patients with coexisting genetic and postsurgical hypoparathyroidism.

A 26-year-old man was evaluated for an elevated serum bone-specific alkaline phosphatase (BSAP). His medical history was significant for a neurodevelopmental disorder with generalized epilepsy. Symptoms included chronic pain in the ankles, hands, and right ribs, and a progressive decline in physical activity. Vitamin D deficiency was discovered, but the elevated BSAP persisted despite vitamin D replacement. Imaging studies reported diffusely increased scintigraphic uptake in the axial and appendicular skeleton, and low bone mineral density, but no radiographic sclerotic or lytic lesions. Genetic screening revealed a heterozygous pathogenic variant in the sodium voltage-gated channel α subunit 8 gene (SCN8A) (c.2924 T>A; p.L975*). Loss-of-function mutations in SCN8A are responsible for neurologic disease and bone loss. Expression analysis revealed that SCN8A was present in human osteoblasts and osteocytes, but not in osteoclasts, suggesting that the voltage-gated sodium channel, Nav1.6, encoded by SCN8A, may have direct actions in bone. The patient was subsequently prescribed alendronate, resulting in a lower alkaline phosphatase and symptomatic improvement in bone pain.

A 30-yr-old man developed right lower leg pain and a palpable solid mass. Radiographic imaging revealed a periosteal reaction with an exostotic mass arising from the right distal fibula. Generalized skeletal osteosclerosis with periosteal reaction was discovered on a radiographic skeletal survey. A biopsy of the right fibular mass revealed reactive woven bone. The patient was referred to a metabolic bone disease clinic, where laboratory values were consistent with secondary hyperparathyroidism and increased bone turnover. A DXA bone density scan revealed high bone density, with an L1–4 spine Z-score of +9.3, a left femoral neck Z-score of +8.5, and a total hip Z-score of +6.5. A dental exam revealed generalized gingival inflammation, teeth mobility, generalized horizontal alveolar bone loss and widening of the periodontal ligament space, increased bone density around the teeth, and thickening of the radicular lamina dura. An extensive evaluation was performed, with the result of a single test revealing the diagnosis. The differential diagnoses of osteosclerosis affecting the skeleton, teeth, and oral cavity are discussed.

Background: Hypercalcemia of malignancy (HCM) is the most common metabolic complication of malignancies, but its incidence may be declining due to potent chemotherapeutic agents. The high mortality associated with HCM has declined markedly due to the introduction of increasingly effective chemotherapeutic drugs. Despite the widespread availability of efficacious medications to treat HCM, evidence-based recommendations to manage this debilitating condition are lacking.Objective: To develop guidelines for the treatment of adults with HCM.Methods: A multidisciplinary panel of clinical experts, together with experts in systematic literature review, identified and prioritized 8 clinical questions related to the treatment of HCM in adult patients. The systematic reviews (SRs) queried electronic databases for studies relevant to the selected questions. The Grading of Recommendations Assessment, Development and Evaluation (GRADE) methodology was used to assess the certainty of evidence and make recommendations. An independent SR was conducted in parallel to assess patients' and physicians' values and preferences, costs, resources needed, acceptability, feasibility, equity, and other domains relevant to the Evidence-to-Decision framework as well as to enable judgements and recommendations.Results: The panel recommends (strong recommendation) in adults with HCM treatment with denosumab (Dmab) or an intravenous (IV) bisphosphonate (BP). The following recommendations were based on low certainty of the evidence. The panel suggests (conditional recommendation) (1) in adults with HCM, the use of Dmab rather than an IV BP; (2) in adults with severe HCM, a combination of calcitonin and an IV BP or Dmab therapy as initial treatment; and (3) in adults with refractory/recurrent HCM despite treatment with BP, the use of Dmab. The panel suggests (conditional recommendation) the addition of an IV BP or Dmab in adult patients with hypercalcemia due to tumors associated with high calcitriol levels who are already receiving glucocorticoid therapy but continue to have severe or symptomatic HCM. The panel suggests (conditional recommendation) in adult patients with hypercalcemia due to parathyroid carcinoma, treatment with either a calcimimetic or an antiresorptive (IV BP or Dmab). The panel judges the treatments as probably accessible and feasible for most recommendations but noted variability in costs, resources required, and their impact on equity.Conclusions: The panel's recommendations are based on currently available evidence considering the most important outcomes in HCM to patients and key stakeholders. Treatment of the primary malignancy is instrumental for controlling hypercalcemia and preventing its recurrence. The recommendations provide a framework for the medical management of adults with HCM and incorporate important decisional and contextual factors. The guidelines underscore current knowledge gaps that can be used to establish future research agendas.

Bone metastasis is a complication of prostate cancer in up to 90% of men afflicted with advanced disease. Therapies that reduce androgen exposure remain at the forefront of treatment. However, most prostate cancers transition to a state whereby reducing testicular androgen action becomes ineffective. A common mechanism of this transition is intratumoral production of testosterone (T) using the adrenal androgen precursor dehydroepiandrosterone (DHEA) through enzymatic conversion by 3β- and 17β-hydroxysteroid dehydrogenases (3βHSD and 17βHSD). Given the ability of prostate cancer to form blastic metastases in bone, we hypothesized that osteoblasts might be a source of androgen synthesis. RNA expression analyses of murine osteoblasts and human bone confirmed that at least one 3βHSD and 17βHSD enzyme isoform was expressed, suggesting that osteoblasts are capable of generating androgens from adrenal DHEA. Murine osteoblasts were treated with 100 nM and 1 μM DHEA or vehicle control. Conditioned media from these osteoblasts were assayed for intermediate and active androgens by liquid chromatography–tandem mass spectrometry. As DHEA was consumed, the androgen intermediates androstenediol and androstenedione were generated and subsequently converted to T. Conditioned media of DHEA-treated osteoblasts increased androgen receptor (AR) signaling, prostate-specific antigen (PSA) production, and cell numbers of the androgen-sensitive prostate cancer cell lines C4-2B and LNCaP. DHEA did not induce AR signaling in osteoblasts despite AR expression in this cell type. We describe an unreported function of osteoblasts as a source of T that is especially relevant during androgen-responsive metastatic prostate cancer invasion into bone. © 2021 American Society for Bone and Mineral Research (ASBMR). This article has been contributed to by US Government employees and their work is in the public domain in the USA.

Purpose Spinal metastases are common in cancer. This preferential migration/growth in the spine is not fully understood. Dura has been shown to affect the surrounding microenvironment and promote cancer growth. Here, we investigate the role of dural cytokines in promoting the metastatic potential of prostate cancer (PCa) and the involvement of the CXCR2 signaling pathway. Methods The role of dural conditioned media (DCM) in proliferation, migration and invasion of five PCa cell lines with various hormone sensitivities was assessed in the presence or absence of the CXCR2 inhibitor, SB225002. CXCR2 surface protein was examined by FACS. Cytokine levels were measured using a mouse cytokine array. Results We observed high levels of cytokines produced by dura and within the vertebral body bone marrow, namely CXCL1 and CXCL2, that act on the CXCR2 receptor. All prostate cell lines treated with DCM demonstrated significant increase in growth, migration and invasion regardless of androgen sensitivity, except PC3, which did not significantly increase in invasiveness. When treated with SB225002, the growth response to DCM by cells expressing the highest levels of CXCR2 as measured by FACS (LNCaP and 22Rv1) was blunted. The increase in migration was significantly decreased in all lines in the presence of SB225002. Interestingly, the invasion increase seen with DCM was unchanged when these cells were treated with the CXCR2 inhibitor, except PC3 did demonstrate a significant decrease in invasion. Conclusion DCM enhances the metastatic potential of PCa with increased proliferation, migration and invasion. This phenomenon is partly mediated through the CXCR2 pathway.

Authors: Henry H. Moon, Katrina L. Clines, Patrick J. O’Day, Basel M. Al-Barghouthi, Emily A. Farber, Charles R. Farber, Richard J. Auchus Affiliations: University of Michigan, Ann Arbor, Michigan; University of Virginia, Charlottesville, Virginia; Veterans Affairs Medical Center, Ann Arbor, Michigan Abstract Body: Bone metastasis is a complication of prostate cancer

Bone metastasis is a painful complication of advanced prostate cancer. Endothelin-1 is a tumor-secreted factor that plays a central role in osteoblast activation and the osteosclerotic response of prostate cancer metastatic to bone. Antagonists that block the activation of the endothelin A receptor (ET_AR), located on osteoblasts, reduce osteoblastic bone lesions in animal models of bone metastasis. However, ET_AR antagonists demonstrated limited efficacy in clinical trials of men with advanced prostate cancer who also received standard androgen deprivation therapy (ADT). Previous data from our group suggested that, in a mouse model, ET_AR antagonists might only be efficacious when androgen signaling in the osteoblast is lowered beyond the ability of standard ADT. This notion was tested in a mouse model of prostate cancer bone metastasis. Castrated and sham-operated male athymic nude mice underwent intracardiac inoculation of the ARCaP_M castration-resistant prostate cancer cell line. The mice were then treated with either the ET_AR antagonist zibotentan or a vehicle control to generate four experimental groups: vehicle+sham (Veh+Sham), vehicle+castrate (Veh+Castr), zibotentan+sham (Zibo+Sham), and zibotentan+castrate (Zibo+Castr). The mice were monitored radiographically for the development of skeletal lesions. The Zibo+Castr group had significantly longer survival and a single incidental lesion. Mice in the Zibo+Sham group had the shortest survival and the largest number of skeletal lesions. Survival and skeletal lesions of the Veh+Sham and Veh+Castr groups were intermediate compared with the zibotentan-treated groups. We report a complex interaction between ET_AR and androgen signaling, whereby ET_AR blockade was most efficacious when combined with complete androgen deprivation.