New CRISPR-based System Will Open the Door to Targeted Immunotherapies of the Next Generation – ScienceDaily

Researchers at the University of San Francisco (UC San Francisco) have developed a system called SLICE, based on CRISPR, that will allow scientists to quickly assess the function of each gene in "primary" immune cells – those that come directly from patients. The new method, described in the November 15 edition of Cell, provides researchers with a powerful tool that will guide them in making decisions when determining the best way to develop immune cells to fight cancer and a host of other diseases.

"SLICE allows us to perform genome-wide screenings in which we mutate all genes in the genome to see which genes have the greatest effect on the cell behavior we are interested in," explained Alex Marson. , MD, PhD, Associate Professor of Microbiology. and immunology at UCSF and co-lead author of the new study. "We are modifying one gene at a time in each cell and see what change the cell is doing to do what we want.Slice is the discovery engine that will point us to ways that we can reprogram to generate the most efficient generation possible. cellular therapies. "

SLICE discovers genes that boost immune activity killing cancer

To prove their principle, researchers tested whether they could use SLICE to identify the genes that make T cells – a common type of immune cell – replicate more efficiently. This is especially important for cancer immunotherapy, which uses artificially stimulated and artificially modified T cells to kill cancer. Until now, these therapies have only been effective against some malignant tumors, but scientists believe that identifying genes that promote T-cell proliferation can render cancer immunotherapy accessible to a larger number of patients.

Thanks to SLICE, researchers have been able to identify genes that promote the replication of T lymphocytes and others that suppress it. Although some of these genes have already been characterized with the aid of other discovery methods, many were entirely new, demonstrating that SLICE could reveal key regulators of proliferation that other methods can not. 39 have failed to capture.

After identifying these genes, the researchers obtained primary T cells from multiple human donors and deleted the genes that inhibited replication. When these CRISPR-modified T cells were cultured in the presence of cancer, they showed a markedly improved cancer-killing capacity, demonstrating that scientists could edit the genes identified by SLICE and transform ordinary T-cells into a potent potential treatment.

Challenge the defenses of cancer

But cancer has its own tips. Cancer immunotherapy often fails because tumors develop in microenvironments that abound with compounds that suppress immune activity and prevent T cells from achieving their full anticancer potential.

"T cells seem to become" suppressed "in tumor microenvironments," said Julia Carnevale, MD, a health oncologist, associate researcher at the Damon Runyon Cancer Foundation and co-first author of the new study. "We wanted to know if SLICE could help us find a way to help T cells overcome this deletion."

Researchers have shown that SLICE can actually be used to reinvigorate suppressed T cells. With the help of SLICE, researchers identified genes targeted by adenosine, an immunosuppressant found in tumor microenvironments, and found that suppressing these genes allowed T cells to proliferate, even in the presence of adenosine.

"SLICE works as a flexible platform that allows scientists to model the interaction between immune cells and the microenvironment of the tumor.We have shown that SLICE can help them identify genes that allow immune cells to Escape the immunosuppressive forces encountered in these microenvironments, "said Alan Ashworth, Ph.D., E. Dixon Heise's distinguished professor of oncology at UCSF, president of UCSF's Helen Diller Family Cancer Treatment Center and co-lead author of the new study.

SLICE is the discovery engine for next-generation immune cell therapies

SLICE relies on a recent discovery from the Marson laboratory. In July 2018, researchers at Marson Lab indicated in Nature that they could incorporate CRISPR-based gene editing constructs into immune cells using electroporation, a technique in which cells are literally shocked to absorb molecules from outside the cell. SLICE takes a hybrid approach, incorporating the best aspects of the Marson Lab's electroporation method alongside more conventional methods that use viruses to provide CRISPR system components. Once SLICE has identified the genomic targets, the CRISPR method based on electroporation could be used to reconfigure these targets and reprogram the immune cells, thus strengthening their therapeutic capacity.

SLICE is also a major advance over current tools used by scientists to study gene function. Although existing methods – including RNAi interference (RNAi) and some CRISPR-based approaches – have provided important information, their use is limited to cell lines that often fail to capture the actual biology in which researchers work. interest the most. In addition, SLICE could be used to interrogate regions of the genome that do not encode proteins – a major advance over RNAi, limited to coding regions of the genome.

Most importantly, the potential applications of SLICE are not limited to what is described in the new document, said Marson, scientific director of biomedicine at the UC Berkeley-UCSF Innovative Genomics Institute, and is also affiliated with the Parker Institute. for Cancer. Immunotherapy, who funded the new study.

"Given the flexibility of this approach," said Marson, "SLICE may one day help scientists create custom immune cells with new anti-disease properties."