CAR-T细胞,基因编辑 z-bo 2020-09-30 403

　　In a new study, researchers at the University of Pennsylvania and Stanford University combined two state-of-the-art methods-CRISPR (DNA editing) and T cell therapy (using immune system sentinels to destroy tumors). ---Together opened a new chapter in the rapid development of cancer immunotherapy. They reported that two women over the age of 60 and one man had sarcomas, and the other two had blood cancers called multiple myeloma. Last year, three patients received their own CRISPR gene-edited immune cell therapy.

　　For these three patients, the benefit is limited. One person died, and the other two became worse. However, the corresponding author of the paper, University of Pennsylvania cancer researcher Karl June (Karl June), said that the long-term regulatory review of the clinical trial is not aimed at treating cancer. The purpose is to prove that the strategy is feasible and safe. As far as this indicator is concerned, scientists believe it is successful. Fyodor Urnov, a genome editor at the University of California, Berkeley, said: "This is a decisive turning point." He said that this study is the first in the United States to answer "a problem that clearly plagues this field." .

　　These researchers combined CRISPR with another strategy to integrate new DNA into immune cells. June and his team helped develop this strategy in 2010 when they added DNA to the T cells of three male patients with chronic leukemia and injected these T cells into the same patient. The results of the treatment are worth noting: the two male patients are still healthy. Others are testing the same method called CAR-T cell therapy-introducing chimeric antigen receptor (CAR) genes into T cells, allowing these T cells to perfuse patients to bind and destroy. Cancer cells that express specific proteins on their surface. The process of preparing CAR-T cells usually takes 4-6 weeks. Today, two CAR-T cell therapies have been approved for the treatment of leukemia and lymphoma patients.

　　However, over time, the limitations of this therapy have gradually attracted attention. Edward Statmauer, the lead author of the paper on the treatment of blood cancer at the University of Pennsylvania, said that not all cancer patients will benefit, and even the beneficiaries will relapse. Solid tumors such as brain tumors and pancreatic tumors have proven difficult to treat.

　　People want to use CRISPR to knock out selected genes and add DNA. This can make T cells stronger and more durable. However, CRISPR introduces its own uncertainty. Laboratory studies have shown that there is an "off-target" effect, that is, unexpected DNA modification. No one knows whether T cells carrying this gene can survive in humans. Last year, Vertex Pharmaceuticals and CRISPR Therapeutics announced that two patients with inherited hematological diseases who received CRISPR-edited cell therapy performed well, but did not disclose too many details.

　　In June, Stadtmauer and colleagues searched for the first time patients whose tumors produce a protein called NY-ESO-1, and added the gene encoding the protein to extract from these patients. T cells. These patients also need to carry certain types of human leukocyte antigen (HLA). It is an immune protein complex that helps T cells perfuse and multiply in the patient's body. All four eligible patients are very sick and often receive this new treatment. A female patient with multiple myeloma received three bone marrow transplants. Another female patient with sarcoma in her thirties was sick and could not receive genetically modified T cell therapy in the laboratory, and died of clinical treatment. In order to promote disease resistance of these patients' T cells, these researchers used CRISPR to knock out two genes encoding the so-called T cell receptor (TCR). We also attenuated the third gene encoding the PD-1 protein. June’s research team speculated that PD-1 might block the immune response, and the removal of PD-1 might enhance T cell function. Subsequently, they inserted different genes encoding T cell receptors that target NY-ESO-1 into T cells.

　　In-depth monitoring of these three patients confirmed that CRISPR can cause some off-target changes, including blood sampling to study transgenic T cells in vivo. However, they are rare, and the number of cells with these unexpected DNA changes will gradually disappear over time. Encouragingly, compared with the current CAR-T cell therapy research (about 2 months), these CRISPR gene-edited T cells can last at least 9 months in the body. June said that imaging studies have shown "good healthy T cells," while laboratory studies can fight cancer within a few months of being injected into patients.

　　However, the prognosis of these three patients is not high. The best response was observed in sarcoma patients with reduced primary tumors, but their cancer subsequently deteriorated. Antonioivas, an oncologist at the University of California, Los Angeles, said: “These T cells no longer turn off these genes, but start to play amazing roles.” Ivas, June and others suggested possible reasons, including why receive treatment. Due to the small number of patients and limited targeting of NY-ESO-1 (sometimes with a good safety record), many T cells may not be able to knock out all three genes.

　　Stadtmauer said: "The whole field is full of creativity." Other clinical trials, including China, are providing CRISPR-edited cells for patients with cancer and other diseases. PACT Pharma, established with the support of Ribas, is using CRISPR to conduct clinical trials against gene mutations in solid tumors. Ibas said that the June research team provided a "necessary start" for providing CRISPR-edited T cells to patients. He added: "I did this in the first place, so things will be easier."