Car-t cell therapy and gene editing technologies
,1 Amirhossein ahmadi
,2,* Seyed javad hosseini
1. Department of Biology, Faculty of Science, Persian Gulf University, Bushehr, Iran
2. Department of Biology, Faculty of Science, Persian Gulf University, Bushehr, Iran
3. Department of Biology, Faculty of Science, Persian Gulf University, Bushehr, Iran
The increasing prevalence of cancer in human populations has become a major concern, encourage the scientists to find a safe and effective alternative therapy. one new rising alternative is immunotherapy which is harnessing the power of body’s own immune system to battle against cancer. immune system, especially t lymphocytes have a critical role in identification of tumor-specific antigens. adoptive t cell transfer involves ex vivo expansion of fragments of resected tumors or genetically engineered patients derived t cells and sending them back for eliminating tumor cells.
chimeric antigen receptor t (car-t) cell therapy is an effective and durable immunotherapy method which demonstrates better clinical results in hematological malignancies. car-t cells are genetically engineered t cells that express artificial proteins known as chimeric antigen receptor, which navigate these car-expressing immune cells to surface tumor antigens. development of next generation car-t cells using gene editing technologies enhance the therapeutic potential of car-t cell treatment for both hematological and solid tumors. to study the function of the genes and apply targeted manipulation of genome for therapeutic goals, we need highly efficient systems, such as crispr-cas9 to modify existing dna patterns with great accuracy.
in crispr-cas9 system the cas endonuclease is guided by a targeting rna and induce a double strand break (dsb) in target site. crispr/cas9 system from streptococcus pyogenes together with a small guide rna (sgrna) was first used as a genome editing tool in 2013 in mammalian and now become a widely applicable dna editing system. in this system host cell could repair dsb through non-homologues end joining (nhej) or homology directed repair (hdr) which results in insertion/deletion or recombination respectively. the second way be exploited to introduce well defined mutations by transferring altered donor templates into targeted cells. crispr-cas9 is able to significantly expand the kind of cancer and patients that can be treated with car-t cells.
Today expanding the accessibility of current autologous car-t cell therapies face several limitations. this therapy has challenging quality control, being extremely expensive and not being suitable for patients with aggressive disease progression. however, some of these challenges would vanish with the use of allogeneic car-t cell therapy. indeed, limitations in generating autologous car-t cells for each patient led to the idea of making universal or of-the-shelf t cells which derived from healthy donors. but of-the-shelf car-t cells needs to beat graft versus host disease (gvhd). for this purpose, with the use of crispr-cas9 as a multiplex gene editor at a time, researchers investigate ways to silence or disrupt both tcrs and hla molecules.
Recently cispr technology was used as a delivery system to knock in a cd-19 specific car into trac locus that placed the car expression under control of tcr promoter and caused enhanced potency, uniformed car expression, more memory characteristic and less exhausted phenotype in this car. in 2017 the first genetically engineered cellular drug was approved by fda. kymriah and yscarta are two cd-19 directed genetically modified autologous t cells were recently approved by fda as car-t cells that used in patients who had acute lymphoblastic leukemia (all).
Taken together, today hopes have raised for developing next generation car-t cell therapy specially by the use of gene editing technologies. although there is certain safety, efficiency and technical concerns still to be solved the promising results offset the risk.
Cancer, crispr, car-t cell, genome targeting