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

Killing Two Birds with One Stone: Zhejiang University Team Develops "BiKE-Secreting CAR-T" Cells, Enabling T and NK Cells to Cooperate and Overcome Tumor Heterogeneity

Killing Two Birds with One Stone: 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 the field of 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, another strategy—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 that combines the persistent targeted killing capability of CAR-T cells with the broad advantage of bispecific antibodies in activating endogenous immune cells? Yet, existing research lacks a unified strategy that can precisely control tumor targeting, expand the scope of the immune response, and activate multiple types of immune cells 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 of this platform is a bicistronic expression vector, enabling a single CAR-T cell to simultaneously express two weapons:

1. A tumor-targeting Chimeric Antigen Receptor (CAR): Grants the CAR-T cell its own ability to recognize and kill tumor cells.

2. A novel BiKE molecule: This is a "bridge" antibody. One end binds to a tumor antigen (e.g., CD19 or EGFR), and the other end recognizes the activating receptor CD16a on the surface of NK cells.

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

The ingenuity of this design lies in the fact that the infused CAR-T cells act 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 cell active killing + BiKE-activated endogenous NK cell coordinated warfare." This strategy not only amplifies the efficacy of CAR-T itself but, more importantly, mobilizes the patient's inherent immune resources, significantly expanding the scope and intensity of the immune response.

Killing Two Birds with One Stone: Zhejiang University Team Develops "BiKE-Secreting CAR-T" Cells, Enabling T and NK Cells to Cooperate and Overcome Tumor Heterogeneity

Killing Two Birds with One Stone: Zhejiang University Team Develops "BiKE-Secreting CAR-T" Cells, Enabling T and NK Cells to Cooperate and Overcome Tumor Heterogeneity

4. Experimental Validation and Significant Advantages

The research team validated the platform's performance across multiple models:

1. 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 cells at the same dose (especially at low doses). A single infusion combined with periodic NK cell infusions could achieve long-term complete remission.

2. Overcoming Antigen Heterogeneity: In scenarios simulating 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 were able to recognize and kill these tumor cells with antigen heterogeneity, greatly improving the overall anti-tumor effect and effectively addressing immunotherapy failure due to antigen escape.

3. Potential Cost and Safety Advantages:

   • Cost Reduction: This platform does not require the simultaneous preparation of multiple engineered cell types (e.g., both CAR-T and CAR-NK). Using CAR-T as a single carrier may reduce overall treatment complexity and cost.

   • Improved Safety: Compared to the direct injection of bispecific antibody proteins, this system relies on cells to locally and continuously release BiKE, potentially reducing issues related to protein degradation, frequent injections, and systemic toxicity associated with systemic administration.

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. In clinical translation, it not only has the potential to lower the barrier to cell therapy and enhance the ability to cope with complex tumor microenvironments, but its design philosophy of "one platform, dual effects" also 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. It offers a highly promising and innovative path to overcome the current bottlenecks of immunotherapy, particularly the heterogeneity and immunosuppressive microenvironment of solid tumors.