At present, tumor-targeting with monoclonal antibodies (MAbs) is among the most promising novel adjuvant-therapy modalities for the treatment of patients with minimal residual disease of head-and-neck squamous-cell carcinoma (HNSCC). For this purpose we developed MAb U36, recognizing a 200-kDa antigen expressed on the outer cell surface of squamous-cell carcinomas and their normal counterparts. Clinical radioimmunoscintigraphy (RIS) and biodistribution studies have shown that the MAb-U36-defined antigen is a suitable target molecule for antibody-based therapy of head-and-neck cancer. In the present study we further characterized the antigen by cDNA cloning. The cDNA was isolated by expression cloning in COS-7 cells. Sequence analysis and database searching revealed that the MAb-U36-defined antigen is identical to the squamous-cell-specific CD44 splice variant epican. The epitope recognized by MAb U36 was mapped by screening overlapping synthetic peptides of the epican-specific region encoded by exon 7-11 (v3-v7), and appeared to be located in the v6 domain. The applicability of MAb U36 for targeting human tumors of various origin expressing the CD44vb domain is discussed.
Hal et al. (Sat,) studied this question.