In vivo targeting of Hodgkin and Reed-Sternberg cells of Hodgkin's disease with monoclonal antibody Ber-H2 (CD30): immunohistological evidence

Abstract

The ability of the Ber-H2 (CD30) monoclonal antibody (mAb) to target in vivo Hodgkin (H) and Reed-Sternberg (R-S) cells was investigated in six patients with advanced Hodgkin's disease (HD). The patients were injected with scaled-up quantities of 'cold' Ber-H2 mixed-up to a small dose of 131I-labelled Ber-H2, and in vivo binding of the antibody to H and R-S cells was assessed by immunohistological analysis of tumour biopsies and immunoscintigraphy. Only 50% of tumour sites were imaged at scintigraphy by the 131I-labelled Ber-H2. In contrast, immunohistological studies on tissue biopsies, taken 24-72 h following the mAb injection, showed that H and R-S cells in all tumour sites, including those that were not imaged by immunoscintigraphy, were specifically and strongly labelled in vivo by the injected Ber-H2, at a dose as low as 30-50 mg of antibody. In vivo binding of a single dose of Ber-H2 mAb to H and R-S cells did not result in any anti-tumour effect. The excellent in vivo targeting of H and R-S cells with the Ber-H2 mAb may have been the result of multiple favourable factors, including: (a) the restricted expression of the CD30 antigen in normal human tissues; (b) the low level of soluble CD30 in the serum of our patients; and (c) the high affinity of the Ber-H2 mAb for the CD30 molecule. The immunohistological results presented in this study provide a strong argument for using the Ber-H2 mAb as a carrier for delivering cytotoxic agents (isotopes or toxins) to neoplastic cells of HD refractory to conventional therapy.