Isolation and characterization of camelid single-domain antibodies against HER2

OBJECTIVE: To isolate and characterize novel high-affinity llama single-domain antibodies against human HER2. RESULTS: We immunized a llama with human HER2, constructed a phage-displayed V(H)H library from the lymphocytes of the animal, and isolated six unique HER2-specific V(H)Hs by panning. All six V(H)Hs were unique at the amino acid level and were clonally unrelated, as reflected by their distinct CDR3 lengths. All six V(H)Hs recognized recombinant human HER2 ectodomain with monovalent affinities ranging from 1 to 51 nM, had comparable affinities for cynomolgus monkey HER2, and bound HER2(+) SKOV3 cells by flow cytometry. Three of the V(H)Hs recognized recombinant murine HER2 with no loss of affinity compared with human and cynomolgus monkey HER2. The V(H)Hs recognized three major epitopes on HER2 (including one conserved across the human, simian and murine orthologues), all of which were distinct from that of trastuzumab. These V(H)Hs may be useful in the design of modular cancer immunotherapeutics. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (10.1186/s13104-018-3955-8) contains supplementary material, which is available to authorized users.