Tumor-biopsy stratification based on mTOR-pathway activity and functional mutations in the upstream genes PIK3CA and PTEN

Genomics of human congenital hydrocephalus

Congenital hydrocephalus (CH), characterized by enlarged brain ventricles, is considered a disease of pathological cerebrospinal fluid (CSF) accumulation and, therefore, treated largely by neurosurgical CSF diversion. The persistence of ventriculomegaly and poor neurodevelopmental outcomes in some post-surgical patients highlights our limited knowledge of disease mechanisms. Recent whole-exome sequencing (WES) studies have shown that rare, damaging de novo and inherited mutations with large effect contribute to ~ 25% of sporadic CH. Interestingly, multiple CH genes are key regulators of neural stem cell growth and differentiation and converge in human transcriptional networks and cell types pertinent to fetal neurogliogenesis. These data implicate genetic disruption of early brain development as the primary pathomechanism in a substantial minority of patients with sporadic CH, shedding new light on human brain development and the pathogenesis of hydrocephalus. These data further suggest WES as a clinical tool with potential to re-classify CH according to a molecular nomenclature of increased precision and utility for genetic counseling, outcome prognostication, and treatment stratification.

Combination Strategies to Improve Targeted Radionuclide Therapy

In recent years, targeted radionuclide therapy (TRT) has emerged as a promising strategy for cancer treatment. In contrast to conventional radiotherapy, TRT delivers ionizing radiation to tumors in a targeted manner, reducing the dose that healthy tissues are exposed to. Existing TRT strategies include the use of 177Lu-DOTATATE, 131I-metaiodobenzylguanidine, Bexxar, and Zevalin, clinically approved agents for the treatment of neuroendocrine tumors, neuroblastoma, and non-Hodgkin lymphoma, respectively. Although promising results have been obtained with these agents, clinical evidence acquired to date suggests that only a small percentage of patients achieves complete response. Consequently, there have been attempts to improve TRT outcomes through combinations with other therapeutic agents; such strategies include administering concurrent TRT and chemotherapy, and the use of TRT with known or putative radiosensitizers such as poly(adenosine diphosphate ribose) polymerase and mammalian-target-of-rapamycin inhibitors. In addition to potentially achieving greater therapeutic effects than the respective monotherapies, these strategies may lead to lower dosages or numbers of cycles required and, in turn, reduce unwanted toxicities. As of now, several clinical trials have been conducted to assess the benefits of TRT-based combination therapies, sometimes despite limited preclinical evidence being available in the public domain to support their use. Although some clinical trials have yielded promising results, others have shown no clear survival benefit from particular combination treatments. Here, we present a comprehensive review of combination strategies with TRT reported in the literature to date and evaluate their therapeutic potential.

Synthesis and validation of [18F]mBPET-1, a fluorine-18 labelled mTOR inhibitor derivative based on a benzofuran backbone

Background

Targeted therapy of HER2 positive breast cancer has led to clinical success in some cases with primary and secondary resistance being major obstacles. Due to the substantial involvement of mTOR kinase in cell growth and proliferation pathways it is now targeted in combination treatments to counteract HER2 targeted therapy resistance. However, the selection of receptive patient populations for a specific drug combination is crucial. This work aims to develop a molecular probe capable of identifying patients with tumour populations which are receptive to RAD001 combination therapy. Based on the structure of a mTOR inhibitor specific for mTORC1, we designed, synthesised and characterised a novel benzofuran based molecular probe which suits late stage fluorination via Click chemistry.

Results

Synthesis of the alkyne precursor 5 proceeded in 27.5% yield over 7 linear steps. Click derivatisation gave the non-radioactive standard in 25% yield. Radiosynthesis of [¹⁸F]1-((1-(2-Fluoroethyl)-1H-1,2,3-triazol-4-yl) methyl)-4-((5-methoxy-2-phenylbenzofuran-4-yl) methyl) piperazine ([¹⁸F]mBPET-1) proceeded over two steps which were automated on an iPhase FlexLab synthesis module. In the first step, 2-[¹⁸F]fluoroethylazide ([¹⁸F]6) was produced, purified by automated distillation in 60% non-decay-corrected yield and subjected to Click conditions with 5. Semi-preparative RP-HPLC purification and reformulation gave [¹⁸F]mBPET-1 in 40% ± 5% (n = 6) overall RCY with a process time of 90 min. Radiochemical purity was ≥99% at end of synthesis (EOS) and ≥ 98% after 4 h at room temperature. Molar activities ranged from typically 24.8 GBq/μmol (EOS) to a maximum of 78.6 GBq/μmol (EOS). Lipophilicity of [¹⁸F]mBPET-1 was determined at pH 7.4 (logD_7.4 = 0.89). [¹⁸F]mBPET-1 showed high metabolic stability when incubated with mouse S9 liver fractions which resulted in a 0.8% drop in radiochemical purity after 3 h. Cell uptake assays showed 1.3–1.9-fold increased uptake of the [¹⁸F]mBPET-1 in RAD001 sensitive compared to insensitive cells across a panel of 4 breast cancer cell lines.

Conclusion

Molecular targeting of mTOR with [¹⁸F]mBPET-1 distinguishes mTOR inhibitor sensitive and insensitive cell lines. Future studies will explore the ability of [¹⁸F]mBPET-1 to predict response to mTOR inhibitor treatment in in vivo models.

Value-based genomics

Advancements in next-generation sequencing have greatly enhanced the development of biomarker-driven cancer therapies. The affordability and availability of next-generation sequencers have allowed for the commercialization of next-generation sequencing platforms that have found widespread use for clinical-decision making and research purposes. Despite the greater availability of tumor molecular profiling by next-generation sequencing at our doorsteps, the achievement of value-based care, or improving patient outcomes while reducing overall costs or risks, in the era of precision oncology remains a looming challenge. In this review, we highlight available data through a pre-established and conceptualized framework for evaluating value-based medicine to assess the cost (efficiency), clinical benefit (effectiveness), and toxicity (safety) of genomic profiling in cancer care. We also provide perspectives on future directions of next-generation sequencing from targeted panels to whole-exome or whole-genome sequencing and describe potential strategies needed to attain value-based genomics.