The clinical success rate of new oncology drugs is only 3.4% compared to 20.9% in other disease types (Wong et al, 2018). One contributing factor to this issue is the testing systems used, with two-dimensional (2D) monolayer assay formats as the traditional mainstay of high throughput screening. Although 2D monolayer assays have identified many successful drugs, it is increasingly recognized that they do not accurately model key aspects of the three-dimensional (3D) tumor environment. Therefore, the adoption of high throughput screening approaches using 3D assays to complement 2D approaches could substantially improve prediction of clinical outcomes and reduce the high failure rate of cancer drugs in clinical trials.
A major study has been undertaken to gain a better understanding of thousands of mutations in the BRCA1 gene - a key gene in breast and ovarian cancers.
A revolution is under way in functional genomics which is spearheaded by the CRISPR-Cas9 system and its application to pooled genetic screening. Remarkable new tools, made possible by dCas9, are coming to fruition that will allow for a new kind of interrogation of gene function, allowing us to ask more sophisticated questions about the biology of drug targets.
The cellular DNA damage response (DDR) is an essential safeguard against cancer. Upon activation, the DDR can limit tumor progression at the early stages by inducing senescence or cell death. When this defense fails tumors are able to develop. However, with time, tumors accumulate more mutations in DNA repair proteins as cancers progress. The efficiency of DDR plays an essential role in the effectivity of cytotoxic treatments. Currently much research is focused on identifying the DDR mechanisms involved in cancers and how these dysfunctional processes can be utilized against tumor growth.
In a paper published on Nature.com in Scientific Reports, Horizon Discovery have conducted a detailed analysis of CRISPR-Cas9 sensitivity (drop-out) screening to come up with a highly improved and optimized platform. In our analysis, we used a custom ultra-complex sgRNA library and capitalized on Horizon's streamlined screening pipeline to evaluate fundamental aspects of functional genomic screening.
There exist now a range of techniques to perform genome editing, such as ZFN, CRISPR, TALENS and AAV, each with their own strengths and weaknesses. However, one consistent element that has a significant impact on the success of that editing event when generating an isogenic cell line is the choice of parental cell line to be engineered.
Thanks to next-generation sequencing (NGS), we are starting to understand the mutational changes that occur across the board in the cancer genome. With this knowledge comes potential - novel mutated genes and the proteins that they encode are candidates for prognostic markers and/or new drug targets.
It’s hard to keep up with the rapidly expanding world of CRISPR, and it’s starting to feel like CRISPR screens are being published every week, taking the technique from the cutting edge to the mainstream. If you’d like to understand a bit more about CRISPR screens, here’s a number of fantastic publications that have really moved this technology forward.