Engineering T Cells Using CRISPR/Cas9 for Cancer Therapy

The Potential Revolution of Cancer Treatment with CRISPR Technology

Immuno-oncology (IO) and targeted therapies, such as small molecule inhibitors, have changed the landscape of cancer treatment and prognosis; however, durable responses have been difficult to achieve due to tumor heterogeneity, development of drug resistance, and adverse effects that limit dosing and prolonged drug use. To improve upon the current medicinal armamentarium, there is an urgent need for new ways to understand, reverse, and treat carcinogenesis. Clustered regularly interspaced short palindromic repeats (CRISPR)-CRISPR-associated protein (Cas) 9 is a powerful and efficient tool for genome editing that has shown significant promise for developing new therapeutics. While CRISPR/Cas9 has been successfully used for pre-clinical cancer research, its use in the clinical setting is still in an early stage of development. The purpose of this review is to describe the CRISPR technology and to provide an overview of its current applications and future potential as cancer therapies.

A universal and sensitive gene mutation detection method based on CRISPR-Cas12a

Single nucleotide mutations are highly related to the occurrence and development of cancer. The development of simple single nucleotide mutation detection methods with high sensitivity and specificity has great clinical significance for the prevention, diagnosis, treatment and prognosis evaluation of cancer. In recent years, CRISPR/Cas12a has been developed as a highly sensitive, simple and fast tool for nucleic acid detection. However, the specificity and universality of current detection methods based on it are still insufficient, so their clinical applications are limited. Herein, we developed a simple and rapid single nucleotide mutation detection method based on CRISPR/Cas12a system. This method not only solves the problem of PAM sequence restriction of CRISPR/Cas12a, but also significantly improves the specificity of CRISPR/Cas12a for single nucleotide mutation and greatly improves the sensitivity. We detected three clinically significant mutations, PTEN R130Q, BRAF V600E, and TP53 R248W, with a detection limit of 0.1%. Finally, we further verified the clinical practicability of this method. We selected TP53 R248W mutation site for testing. The accuracy of testing results for 10 clinical samples was as high as 100%. In conclusion, the detection method of specific PCR combined with CRISPR/Cas12a is simple, rapid, universal and highly sensitive. We believe that this method has promising application prospects in clinical diagnosis of cancer.

Pan-Cancer Analysis Identifies Tumor Cell Surface Targets for CAR-T Cell Therapies and Antibody Drug Conjugates

Tumor cells can be recognized through tumor surface antigens by immune cells and antibodies, which therefore can be used as drug targets for chimeric antigen receptor-T (CAR-T) therapies and antibody drug conjugates (ADCs). In this study, we aimed to identify novel tumor-specific antigens as targets for more effective and safer CAR-T cell therapies and ADCs. Here, we performed differential expression analysis of pan-cancer data obtained from the Cancer Genome Atlas (TCGA), and then performed a series of conditional screenings including Cox regression analysis, Pearson correlation analysis, and risk-score calculation to find tumor-specific cell membrane genes. A tumor tissue-specific and highly expressed gene set containing 3919 genes from 17 cancer types was obtained. Moreover, the prognostic roles of these genes and the functions of these highly expressed membrane proteins were assessed. Notably, 427, 584, 431 and 578 genes were identified as risk factors for LIHC, KIRC, UCEC, and KIRP, respectively. Functional enrichment analysis indicated that these tumor-specific surface proteins might confer tumor cells the ability to invade and metastasize. Furthermore, correlation analysis displayed that most overexpressed membrane proteins were positively correlated to each other. In addition, 371 target membrane protein-coding genes were sifted out by excluding proteins expressed in normal tissues. Apart from the identification of well-validated genes such as GPC3, MSLN and EGFR in the literature, we further confirmed the differential protein expression of 23 proteins: ADD2, DEF6, DOK3, ENO2, FMNL1, MICALL2, PARVG, PSTPIP1, FERMT1, PLEK2, CD109, GNG4, MAPT, OSBPL3, PLXNA1, ROBO1, SLC16A3, SLC26A6, SRGAP2, and TMEM65 in four types of tumors. In summary, our findings reveal novel tumor-specific antigens, which could be potentially used for next-generation CAR-T cell therapies and ADC discovery.

CRISPR Gene Editing of Human Primary NK and T Cells for Cancer Immunotherapy

Antitumor activity of immune cells such as T cells and NK cells has made them auspicious therapeutic regimens for adaptive cancer immunotherapy. Enhancing their cytotoxic effects against malignancies and overcoming their suppression in tumor microenvironment (TME) may improve their efficacy to treat cancers. Clustered, regularly interspaced short palindromic repeats (CRISPR) genome editing has become one of the most popular tools to enhance immune cell antitumor activity. In this review we highlight applications and practicability of CRISPR/Cas9 gene editing and engineering strategies for cancer immunotherapy. In addition, we have reviewed several approaches to study CRISPR off-target effects.

Current Advances in Immunotherapy for Glioblastoma Multiforme and Future Prospects

Glioblastoma is the most frequent and malignant type of brain tumor. It has a reputation for being resistant to current treatments, and the prognosis is still bleak. Immunotherapies have transformed the treatment of a variety of cancers, and they provide great hope for glioblastoma, although they have yet to be successful. The justification for immune targeting of glioblastoma and the obstacles that come with treating these immunosuppressive tumors are reviewed in this paper. Cancer vaccines, oncolytic viruses (OVs), checkpoint blockade medications, adoptive cell transfer (ACT), chimeric antigen receptor (CAR) T-cells, and nanomedicine-based immunotherapies are among the novel immune-targeting therapies researched in glioblastoma. Key clinical trial outcomes and current trials for each method are presented from a clinical standpoint. Finally, constraints, whether biological or due to trial design, are discussed, along with solutions for overcoming them. In glioblastoma, proof of efficacy for immunotherapy approaches has yet to be demonstrated, but our rapidly growing understanding of the disease’s biology and immune microenvironment, as well as the emergence of novel promising combinatorial approaches, may allow researchers to finally meet the medical need for patients with glioblastoma multiforme (GBM).

Genetical engineering for NK and T cell immunotherapy with CRISPR/Cas9 technology: Implications and challenges

Immunotherapy has become one of the most promising strategies in cancer therapies. Among the therapeutic alternatives, genetically engineered NK/T cell therapies have emerged as powerful and innovative therapeutic modalities for cancer patients with precise targeting and impressive efficacy. Nonetheless, this approach still faces multiple challenges, such as immunosuppressive tumor microenvironment, exhaustion of immune effector cells in tumors, off-target effects manufacturing complexity, and poor infiltration of effector cells, all of which need to be overcome for further utilization to cancers. Recently, CRISPR/Cas9 genome editing technology, with the goal of enhancing the efficacy and increasing the availability of engineered effector cell therapies, has shown considerable potential in the novel strategies and options to overcome these limitations. Here we review the current progress of the applications of CRISPR in cancer immunotherapy. Furthermore, we discuss issues related to the NK/T cell applications, gene delivery methods, efficiency, challenges, and implications of CRISPR/Cas9.

Chimeric antigen receptor T-cell lymphoma immunotherapy: the next questions

PURPOSE OF REVIEW

Chimeric antigen receptor (CAR) T-cell therapy is an innovative form of adoptive cellular immunotherapy targeting CD19 in its most advanced form. Up to 30% of infused patients achieve long-term survival, meaning that 70% of patients still fail to respond or relapse after therapy. This review will address the unresolved issues relating to responders' characterization, relapse prediction, and prevention, CAR T-cell construct optimization, rational combination with other therapies and treatment toxicity, focusing on the management of relapsed/refractory lymphoma patients.

RECENT FINDINGS

Many new antigenic targets are currently investigated and raise the hope of broader successes. However, literature data report that treatment failure is not only related to CAR T construct and infusion but is also due to hostile tumor microenvironment and poor interaction with the host effector cells. Further research should not only target CAR T structure, toxicity and associated therapies, but also tumor-related and host-related microenvironment interactions that lead to treatment failure in relapsed/refractory lymphoma patients.

SUMMARY

Poor persistence of CAR T and loss of CD19 antigen are well established mechanisms of relapse in Acute Lymphoblastic Leukemia (ALL). A fourth generation of CAR T construct is currently investigated to overcome this issue. In non-Hodgkin lymphoma, mechanisms of treatment failure remain poorly understood but tumor and host microenvironment are undoubtedly involved and should be further investigated. A deeper understanding of CAR T-cell therapy failure in individuals will help personalize CAR T-cell therapy in the future.

Improving the anti-solid tumor efficacy of CAR-T cells by inhibiting adenosine signaling pathway

Chimeric antigen receptor T (CAR-T) cell therapy has been applied successfully in treating hematologic malignancies; however, it shows very limited efficacy in treating solid tumors. Adenosine is one of the key immunosuppressive metabolites in tumor microenvironment (TME) of solid tumors. Although the effect of adenosine has been well studied using mouse CAR-T cells, its effect on human CAR-T cells has not been fully elucidated. In particular, there was no evaluation of the CAR-T cells with blocked adenosine signaling in tumor xenograft animal model, which is essential for determining the feasibility of future clinical trials. In this study, we found the expression of A2a receptor (A2AR) and A2b receptor (A2BR) both upregulated in human-derived CAR-T cells, and only A2AR was responsible for adenosine-induced impairment of CAR-T cell function. Disrupting A2AR gene in human CAR-T cells with CRISPR-Cas9 increased the anti-tumor function and prevented the exhaustion of CAR-T cells in vitro. Furthermore, CRL5826-CDX model and two patient-derived xenograft solid tumor models were applied to evaluate the efficacy of A2AR knock-out CAR-T cells, which showed superior capability of inhibiting tumor growth. Taken together, these results demonstrate that A2AR knock-out CAR-T cells have the potential of being an improved CAR-T cell therapy in treating solid tumors.