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Nanobody-based CAR NK cells for possible immunotherapy of MICA+ tumors
Elisha R Verhaar1,2, Willemijn J C van Keizerswaard1, Anouk Knoflook1
1Program in Cellular and Molecular Medicine, Boston Children's Hospital, Harvard Medical School, Boston, MA 02115, USA.
Abstract:
The glycoproteins MICA and MICB are upregulated on the surface of cells undergoing stress, for instance due to (viral) infection or malignant transformation. MICA/B are the ligands for the activating receptor NKG2D, found on cytotoxic immune cells like NK cells, CD8+ T cells, and γδ T cells. Upon engagement of NKG2D, these cells are activated to eradicate the MICA/B-positive targets, assisted by the secretion of cytokines. Nanobodies, or VHHs, are derived from the variable regions of camelid heavy-chain only immunoglobulins. Nanobodies are characterized by their small size, ease of production, stability, and specificity of recognition. We generated nanobodies that recognize membrane-bound MICA with high affinity. Here, we use these nanobodies as building blocks for a chimeric antigen receptor (CAR) to establish VHH-based CAR NK cells. These anti-MICA nanobody-based CAR NK cells recognize and selectively kill MICA-positive tumor cells in vitro and in vivo. We track localization of the VHH-based CAR NK cells to MICA-positive lung metastases by immuno-positron emission tomography imaging.
Insights
Researchers developed nanobody-based CAR NK cells targeting MICA. These engineered cells effectively eliminate MICA-positive tumor cells in vitro and in vivo, offering a promising cancer immunotherapy approach.
Area of Science:
- Immunology
- Biotechnology
- Oncology
Background:
- MICA/B glycoproteins are stress-induced ligands for the NKG2D receptor on cytotoxic immune cells.
- Engagement activates NK cells, CD8+ T cells, and γδ T cells to eliminate MICA/B-positive cells.
- Nanobodies (VHHs) offer stable, specific recognition due to their small size and camelid origin.
Purpose of the Study:
- To develop VHH-based chimeric antigen receptor (CAR) NK cells targeting MICA.
- To evaluate the efficacy of these CAR NK cells against MICA-positive tumor cells.
- To assess the in vivo tracking of CAR NK cells using immuno-positron emission tomography (immuno-PET).
Main Methods:
- Generation of high-affinity nanobodies against membrane-bound MICA.
- Construction of VHH-based CARs using these nanobodies.
- Engineering of CAR NK cells expressing anti-MICA VHH-CARs.
- In vitro and in vivo assessment of tumor cell killing.
- Immuno-PET imaging to track CAR NK cell localization.
Main Results:
- Successfully generated nanobodies recognizing membrane-bound MICA with high affinity.
- Developed VHH-based CAR NK cells that selectively target and kill MICA-positive tumor cells in vitro.
- Demonstrated in vivo efficacy of anti-MICA CAR NK cells against MICA-positive tumors.
- Successfully tracked CAR NK cell localization to MICA-positive lung metastases using immuno-PET.
Conclusions:
- VHH-based CAR NK cells represent a novel and effective strategy for targeting MICA-positive cancers.
- This approach shows promise for targeted cancer immunotherapy and in vivo monitoring.
- Nanobody technology provides a versatile platform for CAR development.
