New Engineering Strategies Boost CAR-NK and CAR-T Cell Therapies Against Cancer

Researchers have identified multiple new approaches to significantly improve engineered immune cell therapies for cancer treatment, with advances in both CAR-T and CAR-NK cell technologies showing promise for overcoming current limitations.

In CAR-T cell research, scientists have found that deleting NR2F6, a nuclear receptor previously recognized as a molecular checkpoint in suppressing immune responses, leads to marked enhancement in the performance of CAR-T cells against solid tumors. The findings suggest that removing NR2F6 helps reinvigorate exhausted CAR-T cells, enabling them to sustain their activity against tumor cells more effectively. This discovery offers insights into overcoming one of the major challenges in cancer immunotherapy—addressing the limited success of CAR-T treatments in targeting solid tumors compared to blood cancers.

Meanwhile, a team at the Institute of Zoology of the Chinese Academy of Sciences developed a breakthrough method for mass-producing natural killer cells for cancer immunotherapy. Instead of modifying mature NK cells, the researchers started with CD34+ hematopoietic stem and progenitor cells taken from cord blood. The team found that a single CD34+ HSPC could generate as many as 14 million iNK cells or 7.6 million CAR-iNK cells. The researchers estimate that one-fifth of a typical cord blood unit could theoretically yield enough cells for thousands or even tens of thousands of treatment doses. The findings were published in Nature Biomedical Engineering.

The Chinese team used a three-stage system. First, they expanded CD34+ HSPCs with the help of irradiated AFT024 feeder cells. Within 14 days, the cells multiplied roughly 800- to 1,000-fold. Next, the expanded cells were cultured with OP9 feeder cells to create artificial hematopoietic organoid aggregates, structures that support efficient NK lineage commitment and development. In the final stage, cells that had committed to becoming NK cells were allowed to mature and multiply further. This process produced highly pure iNK or CAR-iNK cells that expressed endogenous CD16.

Another major improvement was the sharp reduction in viral vector needed for CAR engineering. Compared with the amount usually required to modify mature NK cells, this method used only about ~1/140,000 (by Day 42 of culture) to ~1/600,000 (by Day 49) as much viral vector.

In laboratory testing, both iNK and CAR-iNK cells demonstrated powerful tumor-killing ability. In cell line-derived xenograft and patient-derived xenograft mouse models of human B-cell acute lymphoblastic leukemia, CD19 CAR-iNK cells reduced tumor growth and extended the animals' survival.

Separately, researchers at the Ribeirão Preto Blood Center and the Center for Cell-Based Therapy tested new chimeric antigen receptor designs that include specific costimulatory domains, such as 2B4 and DAP12. These domains act like internal activation circuits, shaping how strongly an NK cell ramps up its attack once the CAR recognizes a target. Using the NK-92 cell line, the team found the modified cells killed tumor cells more effectively, showing stronger anti-cancer activity. The results were published in Frontiers in Immunology.

In the experiments, adding 2B4 and DAP12 helped put the cells in a more aggressive state, making them "ready to attack" and improving their ability to destroy tumors. The researchers also explored a practical way to manage that power: temporary pharmacological control using dasatinib. Rather than permanently altering the cells, dasatinib was used as a short-term tool to modulate activation. Animal models showed that CAR-NK cells built with 2B4-DAP12 and pretreated with dasatinib achieved better tumor control than traditional versions.

The work on cord blood-derived NK cells was supported by the Ministry of Science and Technology of the People's Republic of China and the National Natural Science Foundation of China, along with other funding sources. The CTC is one of the Research, Innovation, and Dissemination Centers funded by FAPESP.