Real-World Evidence to Reinforce Clinical Trial Evidence in Health Technology Assessment: A Critical Review of Real-World Evidence Requirements from Seven Countries and Recommendations to Improve Acceptance.

BACKGROUND: Real-world evidence (RWE) can reinforce clinical trial evidence in health technology assessment (HTA). OBJECTIVES: Review HTA bodies' (HTAbs) requirements for RWE, real uses, and acceptance across seven countries (Brazil, Canada, France, Germany, Italy, Spain, and the United Kingdom) and outline recommendations that may improve acceptance of RWE in efficacy/effectiveness assessments and appraisals processes. METHODS: RWE requirements were summarized based on HTAbs' guidelines. Acceptance by HTAbs was evaluated based on industry experience and case studies. RESULTS: As of June 2022, RWE methodological guidelines were in place in three of the seven countries. HTAbs typically requested analyses based on local data sources, but the preferred study design and data sources differed. HTAbs had individual submission, assessment, and appraisal processes; some allowed early meetings for the protocol and/or results validation, though few involved external experts or medical societies to provide input to assessment and appraisal. The extent of submission, assessment, and appraisal requirements did not necessarily reflect the degree of acceptance. CONCLUSION: All the countries reviewed face common challenges regarding the use of RWE. Our proposals address the need to facilitate collaboration and communication with industry and regulatory agencies and the need for specific guidelines describing RWE design and criteria of acceptance throughout the assessment and appraisal processes.

A histone-mimicking interdomain linker in a multidomain protein modulates multivalent histone binding.

N-terminal histone tails are subject to many posttranslational modifications that are recognized by and interact with designated reader domains in histone-binding proteins. BROMO domain adjacent to zinc finger 2B (BAZ2B) is a multidomain histone-binding protein that contains two histone reader modules, a plant homeodomain (PHD) and a bromodomain (BRD), linked by a largely disordered linker. Although previous studies have reported specificity of the PHD domain for the unmodified N terminus of histone H3 and of the BRD domain for H3 acetylated at Lys14 (H3K14ac), the exact mode of H3 binding by BAZ2B and its regulation are underexplored. Here, using isothermal titration calorimetry and NMR spectroscopy, we report that acidic residues in the BAZ2B PHD domain are essential for H3 binding and that BAZ2B PHD-BRD establishes a polyvalent interaction with H3K14ac. Furthermore, we provide evidence that the disordered interdomain linker modulates the histone-binding affinity by interacting with the PHD domain. In particular, lysine-rich stretches in the linker, which resemble the positively charged N terminus of histone H3, reduce the binding affinity of the PHD finger toward the histone substrate. Phosphorylation, acetylation, or poly(ADP-ribosyl)ation of the linker residues may therefore act as a cellular mechanism to transiently tune BAZ2B histone-binding affinity. Our findings further support the concept of interdomain linkers serving a dual role in substrate binding by appropriately positioning the adjacent domains and by electrostatically modulating substrate binding. Moreover, inhibition of histone binding by a histone-mimicking interdomain linker represents another example of regulation of protein-protein interactions by intramolecular mimicry.

A combinatorial screen of the CLOUD uncovers a synergy targeting the androgen receptor.

Approved drugs are invaluable tools to study biochemical pathways, and further characterization of these compounds may lead to repurposing of single drugs or combinations. Here we describe a collection of 308 small molecules representing the diversity of structures and molecular targets of all FDA-approved chemical entities. The CeMM Library of Unique Drugs (CLOUD) covers prodrugs and active forms at pharmacologically relevant concentrations and is ideally suited for combinatorial studies. We screened pairwise combinations of CLOUD drugs for impairment of cancer cell viability and discovered a synergistic interaction between flutamide and phenprocoumon (PPC). The combination of these drugs modulates the stability of the androgen receptor (AR) and resensitizes AR-mutant prostate cancer cells to flutamide. Mechanistically, we show that the AR is a substrate for γ-carboxylation, a post-translational modification inhibited by PPC. Collectively, our data suggest that PPC could be repurposed to tackle resistance to antiandrogens in prostate cancer patients.

FASIL-MS: An Integrated Proteomic and Bioinformatic Workflow To Universally Quantitate In Vivo-Acetylated Positional Isomers.

Dynamic changes in histone post-translational modifications (PTMs) regulate gene transcription leading to fine-tuning of biological processes such as DNA replication and cell cycle progression. Moreover, specific histone modifications constitute docking sites for recruitment of DNA damage repair proteins and mediation of subsequent cell survival. Therefore, understanding and monitoring changes in histone PTMs that can alter cell proliferation and thus lead to disease progression are of considerable medical interest. In this study, stable isotope labeling with N-acetoxy-D3-succinimide (D3-NAS) was utilized to efficiently derivatize unmodified lysine residues at the protein level. The sample preparation method was streamlined to facilitate buffer exchange between the multiple steps of the protocol by coupling chemical derivatization to filter-aided sample preparation (FASP). Additionally, the mass spectrometry method was adapted to simultaneously coisolate and subsequently cofragment all differentially H3/D3-acetylated histone peptide clusters. Combination of these multiplexed MS(2) spectra with the implementation of a data analysis algorithm enabled the quantitation of each and every in vivo-acetylated DMSO- and SAHA-treated H4(4-17) and H3(18-26) peptide. We have termed our new approach FASIL-MS for filter-aided stable isotopic labeling coupled to mass spectrometry. FASIL-MS enables the universal and site-specific quantitation of peptides with multiple in vivo-acetylated lysine residues. Data are available via ProteomeXchange (PXD003611).

Wapl is an essential regulator of chromatin structure and chromosome segregation.

Mammalian genomes contain several billion base pairs of DNA that are packaged in chromatin fibres. At selected gene loci, cohesin complexes have been proposed to arrange these fibres into higher-order structures, but how important this function is for determining overall chromosome architecture and how the process is regulated are not well understood. Using conditional mutagenesis in the mouse, here we show that depletion of the cohesin-associated protein Wapl stably locks cohesin on DNA, leads to clustering of cohesin in axial structures, and causes chromatin condensation in interphase chromosomes. These findings reveal that the stability of cohesin-DNA interactions is an important determinant of chromatin structure, and indicate that cohesin has an architectural role in interphase chromosome territories. Furthermore, we show that regulation of cohesin-DNA interactions by Wapl is important for embryonic development, expression of genes such as c-myc (also known as Myc), and cell cycle progression. In mitosis, Wapl-mediated release of cohesin from DNA is essential for proper chromosome segregation and protects cohesin from cleavage by the protease separase, thus enabling mitotic exit in the presence of functional cohesin complexes.

Cohesin mediates transcriptional insulation by CCCTC-binding factor.

Cohesin complexes mediate sister-chromatid cohesion in dividing cells but may also contribute to gene regulation in postmitotic cells. How cohesin regulates gene expression is not known. Here we describe cohesin-binding sites in the human genome and show that most of these are associated with the CCCTC-binding factor (CTCF), a zinc-finger protein required for transcriptional insulation. CTCF is dispensable for cohesin loading onto DNA, but is needed to enrich cohesin at specific binding sites. Cohesin enables CTCF to insulate promoters from distant enhancers and controls transcription at the H19/IGF2 (insulin-like growth factor 2) locus. This role of cohesin seems to be independent of its role in cohesion. We propose that cohesin functions as a transcriptional insulator, and speculate that subtle deficiencies in this function contribute to 'cohesinopathies' such as Cornelia de Lange syndrome.