Novel Engineered Cell Platform: T Cells and NK Cells "Fighting in Concert"

Killing two birds with one stone: A Zhejiang University team develops "BiKE-secreting CAR-T" cells, enabling T and NK cells to cooperate and overcome tumor heterogeneity.

1. Core Background: The Dilemma of Monotherapies and the Challenge of Combination Strategies

In tumor immunotherapy, CAR-T cell therapy has achieved revolutionary success in blood cancers but still faces challenges such as limited efficacy in solid tumors, antigen escape, high production costs, and toxic side effects. Concurrently, bispecific antibodies (e.g., BiTE/BiKE) can effectively activate and redirect the patient's own readily available T cells or NK cells. However, as protein drugs, they have a short half-life, require frequent injections, do not lower overall costs, and may cause systemic toxicity.

An ideal solution would be: Can we design a novel system combining the persistent targeted killing of CAR-T cells with the broad advantage of bispecific antibodies in activating endogenous immune cells? Existing research lacks a unified strategy that can precisely control tumor targeting, expand the immune response, and activate multiple immune cell types while ensuring safety.

2. Innovative Breakthrough: The BiKE-Secreting CAR-T Cell Platform

Addressing this challenge, a team led by Professor Jie Sun and Professor He Huang from the First Affiliated Hospital, Zhejiang University School of Medicine / Liangzhu Laboratory published groundbreaking research in Nature Biomedical Engineering. They developed a novel engineered cell platform: integrating a secretory bispecific NK cell engager (BiKE) into traditional CAR-T cells.

The core design is a bicistronic expression vector, enabling a single CAR-T cell to simultaneously express two weapons:

• A tumor-targeting Chimeric Antigen Receptor (CAR): Grants the CAR-T cell its own ability to recognize and kill tumor cells.
• A novel BiKE molecule: A "bridge" antibody. One end binds a tumor antigen (e.g., CD19 or EGFR), and the other recognizes the activating receptor CD16a on the surface of NK cells.

3. Mechanism of Action: The "Core Factory" and "Coordinated Warfare"

The ingenuity lies in the infused CAR-T cells acting as "mobile core factories" within the patient:

• Active killing: CAR-T cells use their CAR to directly attack tumor cells.
• Synergistic activation: CAR-T cells continuously secrete BiKE molecules locally at the tumor site. These BiKEs act like "intelligent double-sided tape," recruiting and activating the patient's own non-engineered, natural NK cells, guiding them to attack the tumor cells locked by the other end of the BiKE.

This creates an immune synergy of "CAR-T active killing + BiKE-activated endogenous NK coordinated warfare." This strategy not only amplifies CAR-T efficacy but, more importantly, mobilizes the patient's inherent immune resources, significantly expanding the scope and intensity of the immune response.

4. Experimental Validation and Significant Advantages

• Significantly enhanced efficacy: In CD19+ leukemia and EGFR+ ovarian cancer models, BiKE-secreting CAR-T cells showed significantly superior tumor suppression compared to traditional CAR-T at the same dose (especially at low doses). A single infusion combined with periodic NK infusions could achieve long-term complete remission.
• Overcoming antigen heterogeneity: In simulations of heterogeneous tumor antigen expression, traditional CAR-T could not eliminate tumor subpopulations lacking the target antigen. However, the NK cells activated by BiKE-secreting CAR-T could recognize and kill these tumor cells, effectively addressing immunotherapy failure due to antigen escape.
• Potential cost and safety advantages: Cost reduction, as the platform does not require simultaneous preparation of multiple engineered cell types (e.g., both CAR-T and CAR-NK). Improved safety: compared to direct injection of bispecific antibody proteins, this system relies on cells to locally and continuously release BiKE, reducing systemic toxicity.

5. Significance and Future Prospects

This research demonstrates a new paradigm combining cell engineering and immune regulation. By endowing CAR-T cells with the dual functions of "killing + activation," it achieves a more comprehensive and intelligent mobilization of the anti-tumor immune environment.

In the future, this platform is poised to serve as a technological foundation for next-generation multifunctional immunotherapy. Its "one platform, dual effects" design philosophy provides a scalable blueprint for developing novel therapies targeting other antigens or combining with other immune cells (e.g., macrophages).

Conclusion: The BiKE-secreting CAR-T platform developed by the Sun/Huang team ingeniously combines the persistence of adoptive cell therapy with the broad mobilizing power of bispecific antibodies, offering a highly promising path to overcome the current bottlenecks of immunotherapy, particularly the heterogeneity and immunosuppressive microenvironment of solid tumors.