CD38-Specific Biparatopic Heavy Chain Antibodies Display Potent Complement-Dependent Cytotoxicity Against Multiple...

Area of Science:

• Immunology
• Oncology
• Biotechnology

Background:

• CD38 is a target in multiple myeloma due to its overexpression on cancer cells.
• Nanobodies are single-domain antibody fragments with therapeutic potential.
• Previous work identified llama nanobodies targeting distinct CD38 epitopes.

Purpose of the Study:

• To engineer and evaluate chimeric heavy chain antibodies (hcAbs) derived from llama nanobodies targeting CD38.
• To assess the complement-dependent cytotoxicity (CDC) of these hcAbs against multiple myeloma and Burkitt lymphoma cell lines.
• To explore strategies for enhancing CDC, including combinations, biparatopic designs, and specific mutations.

Main Methods:

• Fusion of llama nanobody VHH domains to human IgG1 Fc regions to create hcAbs.
• Testing hcAb-mediated CDC on CD38-expressing cancer cell lines.
• Evaluating combinations of hcAbs and daratumumab with hcAbs.
• Introducing the E345R HexaBody mutation into hcAbs.
• Constructing biparatopic hcAbs by fusing nanobody dimers to IgG1 Fc regions.

Main Results:

• Combinations of two distinct CD38-specific hcAbs demonstrated potent CDC, unlike monotherapy.
• Combining daratumumab with a non-overlapping epitope-targeting hcAb significantly enhanced CDC.
• The E345R HexaBody mutation markedly increased hcAb CDC potency.
• Soluble, biparatopic hcAbs showed superior CDC against myeloma cells compared to daratumumab.
• Nanobody-based bispecific antibodies offer advantages over traditional VH/VL domain pairings.

Conclusions:

• Engineered nanobodies, particularly biparatopic hcAbs, are effective in mediating CDC against CD38-expressing multiple myeloma.
• Combining nanobody-based hcAbs with existing therapies or using biparatopic designs can overcome limitations of monotherapy.
• These novel CD38-specific biparatopic hcAbs represent promising new therapeutic candidates for multiple myeloma treatment.