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Identification and characterization of blocking nanobodies against human CD70
Xin Zhang1, Chang Liu1, Yuan Xie1
1Xinjiang Key Laboratory of Biological Resources and Genetic Engineering, College of Life Science and Technology, Xinjiang University, Urumqi 830046, China.
Abstract:
CD70 is overexpressed in a variety of solid and hematological tumors and plays a role in tumor proliferation and evasion of immune surveillance. Targeting and blocking its binding to the receptor CD27 have the potential to treat CD70-dependent tumors. To generate novel CD70 blocking agents, we screen a human CD70-immunized camel VHH phage display library and isolate two blocking nanobodies against human CD70 targeting different epitopes. Upon enrichment by three rounds of biopanning, two strategies are employed to identify CD70 blockers. One named affinity selection is used for detecting clones with CD70 binding by conventional PE-ELISA. However, no clone with a blocking effect is obtained from 188 enriched clones by this method. The alternative strategy named competitive selection is based on the inhibiting capacity of CD70-CD27 binding by enriched VHHs. By this method, two clones, Nb-2B3 and Nb-3B6, with strong blocking capacity are obtained from 20 enriched VHHs, suggesting the efficiency of this strategy. Furthermore, Nb-2B3 and Nb-3B6 specifically bind to CD70-positive SKOV3 and Raji cells at low concentrations. Meanwhile, Nb-2B3 has no competitive effect on the binding of Nb-3B6 to CD70, and vice versa, indicating that they target two different epitopes on CD70. Our data show that nanobodies Nb-2B3 and Nb-3B6 are potential attractive theranostic agents for CD70-expressing cancers.
Insights
Researchers developed novel nanobodies, Nb-2B3 and Nb-3B6, that effectively block CD70-CD27 interactions. These nanobodies show promise as theranostic agents for treating CD70-expressing cancers.
Area of Science:
- Immunology
- Oncology
- Biotechnology
Background:
- CD70 overexpression in various cancers promotes tumor growth and immune evasion.
- Blocking the CD70-CD27 interaction is a potential therapeutic strategy for CD70-dependent tumors.
Purpose of the Study:
- To generate and characterize novel nanobodies that block CD70 binding to CD27.
- To identify effective CD70-blocking agents for cancer therapy.
Main Methods:
- Screening a camel VHH phage display library against human CD70.
- Employing affinity selection and competitive selection strategies to identify blocking nanobodies.
- Validating nanobody binding specificity to CD70-positive cancer cell lines (SKOV3, Raji).
Main Results:
- Two blocking nanobodies, Nb-2B3 and Nb-3B6, were isolated using competitive selection.
- These nanobodies specifically bind to CD70-expressing cells at low concentrations.
- Nb-2B3 and Nb-3B6 target distinct epitopes on CD70, as shown by competitive binding assays.
Conclusions:
- Nanobodies Nb-2B3 and Nb-3B6 are potent inhibitors of CD70-CD27 interaction.
- These nanobodies demonstrate potential as theranostic agents for CD70-expressing cancers.
