A fc-engineered NKG2D × B7-H3 bispecific antibody enhances the antitumor activity by orchestrating cytotoxic lymphocytes

Area of Science:

• Immunology
• Cancer Biology
• Biotechnology

Background:

• B7-H3 is an immune-checkpoint molecule overexpressed in various cancers, making it a target for immunotherapy.
• Current immunotherapies often focus on T cells, overlooking the potential of Natural Killer (NK) cells.
• NKG2D is a key activating receptor on cytotoxic immune cells, crucial for anti-tumor responses.

Purpose of the Study:

• To develop and evaluate novel bispecific antibodies (bsAbs) targeting B7-H3 and NKG2D for enhanced cancer immunotherapy.
• To optimize antibody formats for improved efficacy, including antibody-dependent cell-mediated cytotoxicity (ADCC).
• To investigate the synergistic effects of combining B7-H3 × NKG2D bsAbs with other T cell-engaging therapies.

Main Methods:

• Phage display was used to generate specific anti-NKG2D nanobodies.
• Various B7-H3 × NKG2D bispecific antibody formats were constructed and screened.
• In vitro and in vivo studies were conducted to assess antibody-mediated tumor cell lysis and anti-tumor immunity.
• Antibody-dependent cell-mediated cytotoxicity (ADCC) was evaluated for optimized antibody variants.

Main Results:

• A lead candidate antibody, B1-C53, was identified and further engineered into FC-C53 with an optimized Fc fragment.
• FC-C53 demonstrated enhanced tumor lysis in vitro and in vivo by engaging both NK cells and CD8+ T cells.
• Combined administration of FC-C53 with a B7-H3 × CD3 bispecific T cell engager significantly boosted anti-tumor immunity.

Conclusions:

• The B7-H3 × NKG2D bispecific antibody strategy offers a promising approach to enhance anti-B7-H3 immunotherapy.
• FC-C53 effectively orchestrates cytotoxic lymphocytes, including NK and T cells, for improved tumor eradication.
• This study provides a foundation for developing next-generation immunotherapies targeting B7-H3+ cancers.