Patient-derived head and neck cancer organoids allow treatment stratification and serve as a tool for biomarker validation and identification

This article provides a status report on the global burden of cancer worldwide using the GLOBOCAN 2018 estimates of cancer incidence and mortality produced by the International Agency for Research on Cancer, with a focus on geographic variability across 20 world regions. There will be an estimated 18.1 million new cancer cases (17.0 million excluding nonmelanoma skin cancer) and 9.6 million cancer deaths (9.5 million excluding nonmelanoma skin cancer) in 2018. In both sexes combined, lung cancer is the most commonly diagnosed cancer (11.6% of the total cases) and the leading cause of cancer death (18.4% of the total cancer deaths), closely followed by female breast cancer (11.6%), prostate cancer (7.1%), and colorectal cancer (6.1%) for incidence and colorectal cancer (9.2%), stomach cancer (8.2%), and liver cancer (8.2%) for mortality. Lung cancer is the most frequent cancer and the leading cause of cancer death among males, followed by prostate and colorectal cancer (for incidence) and liver and stomach cancer (for mortality). Among females, breast cancer is the most commonly diagnosed cancer and the leading cause of cancer death, followed by colorectal and lung cancer (for incidence), and vice versa (for mortality); cervical cancer ranks fourth for both incidence and mortality. The most frequently diagnosed cancer and the leading cause of cancer death, however, substantially vary across countries and within each country depending on the degree of economic development and associated social and life style factors. It is noteworthy that high-quality cancer registry data, the basis for planning and implementing evidence-based cancer control programs, are not available in most low- and middle-income countries. The Global Initiative for Cancer Registry Development is an international partnership that supports better estimation, as well as the collection and use of local data, to prioritize and evaluate national cancer control efforts. CA: A Cancer Journal for Clinicians 2018;0:1-31. © 2018 American Cancer Society.

Current genome-editing technologies introduce double-stranded (ds) DNA breaks at a target locus as the first step to gene correction. 1,2 Although most genetic diseases arise from point mutations, current approaches to point mutation correction are inefficient and typically induce an abundance of random insertions and deletions (indels) at the target locus from the cellular response to dsDNA breaks. 1,2 Here we report the development of base editing, a new approach to genome editing that enables the direct, irreversible conversion of one target DNA base into another in a programmable manner, without requiring dsDNA backbone cleavage or a donor template. We engineered fusions of CRISPR/Cas9 and a cytidine deaminase enzyme that retain the ability to be programmed with a guide RNA, do not induce dsDNA breaks, and mediate the direct conversion of cytidine to uridine, thereby effecting a C→T (or G→A) substitution. The resulting “base editors” convert cytidines within a window of approximately five nucleotides (nt), and can efficiently correct a variety of point mutations relevant to human disease. In four transformed human and murine cell lines, second- and third-generation base editors that fuse uracil glycosylase inhibitor (UGI), and that use a Cas9 nickase targeting the non-edited strand, manipulate the cellular DNA repair response to favor desired base-editing outcomes, resulting in permanent correction of ∼15-75% of total cellular DNA with minimal (typically ≤ 1%) indel formation. Base editing expands the scope and efficiency of genome editing of point mutations.

Summary The spontaneous deamination of cytosine is a major source of C•G to T•A transitions, which account for half of known human pathogenic point mutations. The ability to efficiently convert target A•T base pairs to G•C therefore could advance the study and treatment of genetic diseases. While the deamination of adenine yields inosine, which is treated as guanine by polymerases, no enzymes are known to deaminate adenine in DNA. Here we report adenine base editors (ABEs) that mediate conversion of A•T to G•C in genomic DNA. We evolved a tRNA adenosine deaminase to operate on DNA when fused to a catalytically impaired CRISPR-Cas9. Extensive directed evolution and protein engineering resulted in seventh-generation ABEs (e.g., ABE7.10), that convert target A•T to G•C base pairs efficiently (~50% in human cells) with very high product purity (typically ≥ 99.9%) and very low rates of indels (typically ≤ 0.1%). ABEs introduce point mutations more efficiently and cleanly than a current Cas9 nuclease-based method, induce less off-target genome modification than Cas9, and can install disease-correcting or disease-suppressing mutations in human cells. Together with our previous base editors, ABEs advance genome editing by enabling the direct, programmable introduction of all four transition mutations without double-stranded DNA cleavage.