We describe three unusual tumours characterized by a mixture of glial and neuronal differentiation, involvement of the posterior fossa and formation of rosettes. Mixed glial-neuronal tumours of the posterior fossa are rare and poorly described neoplasms. However, several distinctive entities have appeared in the literature over recent years under a variety of different names. Our cases demonstrate the morphological features of the 'rosette-forming glioneuronal tumour of the fourth ventricle', a recently identified tumour characterised by its unique location, neurocytic pseudo-rosette formation and the presence of a low grade astrocytoma component. The long term prognosis of these tumours remains unclear. However, the clinical data available including the cases presented here, along with the histological features, suggest that these are low grade tumours with a good prognosis after surgical resection.

Postmenopausal osteoporosis is a disease manifesting in degradation of bone mass and microarchitecture, leading to weakening and increased risk of fracture. Clinical trials are an essential tool for evaluating new treatments and may provide further mechanistic understanding of their effects in vivo. However, the histomorphometry from clinical trials is limited to 2D images and reflects single time points. Biochemical markers of bone turnover give global insight into a drug's action, but not the local dynamics of the bone remodeling process and the cells involved. Additionally, comparative trials necessitate separate treatment groups, meaning only aggregated measures can be compared. In this study, in silico modeling based on histomorphometry and pharmacokinetic data was used to assess the effects of treatment versus control on μCT scans of the same biopsy samples over time, matching the changes in bone volume fraction observed in biopsies from denosumab and placebo groups through year 10 of the FREEDOM Extension trial. In the simulation, treatment decreased osteoclast number, which led to a modest increase in trabecular thickness and osteocyte stress shielding. Long‐term bone turnover suppression led to increased RANKL production, followed by a small increase in osteoclast number at the end of the 6‐month–dosing interval, especially at the end of the Extension study. Lack of treatment led to a significant loss of bone mass and structure. The study's results show how in silico models can generate predictions of denosumab cellular action over a 10‐year period, matching static and dynamic morphometric measures assessed in clinical biopsies. The use of in silico models with clinical trial data can be a method to gain further insight into fundamental bone biology and how treatments can perturb this. With rigorous validation, such models could be used for informing the design of clinical trials, such that the number of participants could be reduced to a minimum to show efficacy. © 2021 The Authors. JBMR Plus published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research.

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Development of BCR-ABL tyrosine kinase inhibitors (TKIs) have improved outcomes for patients diagnosed with chronic myeloid leukemia and Philadelphia chromosome positive acute lymphoblastic leukemia. However, resistance or intolerance to these TKIs still leaves some patients without many treatment options. One point mutation in particular, the T315I mutation, has been shown to be resistant to first and second generation TKIs. The third generation TKI, ponatinib, may provide an option for these patients. Ponatinib (Iclusig®), an orally available, pan-tyrosine kinase inhibitor has a unique binding mechanism allowing inhibition of BCR-ABL kinases, including those with the T315I point mutation. A Phase II study evaluated ponatinib in patients who were resistant or intolerant to nilotinib or dasatinib or patients who had the T315I mutation. In the Phase II study, ponatinib produced a major cytogenetic response in 54% of chronic phase chronic myeloid leukemia patients. It further achieved major hematologic response in 52% of patients in the accelerated phase, 31% of patients in the blast phase, and 41% of Philadelphia chromosome positive acute lymphoblastic leukemia patients. Ponatinib also showed efficacy in patients with the T315I mutation. Serious adverse events included arterial thrombosis, hepatotoxicity, cardiovascular risks, pancreatitis, hemorrhage, fluid retention, myelosuppression, rash, abdominal pain, and embryo–fetal toxicity. Due to the risk of these adverse events and potential drug interactions, the use of ponatinib must be carefully weighed against the benefits in treating patients who have limited treatment options.