Indium-111 bleomycin complex for radiochemotherapy of head and neck cancer — dosimetric and biokinetic aspects

Bleomycin (BLM) is used for the treatment of head and neck cancer. In order to improve the effectiveness of this chemotherapeutic drug, BLM was combined with indium-111. A complex of these agents (¹¹¹In-BLMC), formed at low pH, was injected intravenously into ten head and neck cancer patients in escalating activities of 75, 175 and 375 MBq. The internally delivered dose to the tumours varied from 0.20 to 2.73 mGy at 75 MBq, from 0.33 to 2.51 mGy at 175 MBq, and from 0.87 to 31.3 mGy at the 375 MBq activity level. Uptake of radioactivity was 0.45±0.24×10^–3% ID/g in primary tumours and 0.52±0.20×l0^–3% ID/g in metastases (at 48 h). Tumour volumes varied from 0.51 to 49.0 cm³. The radioactivity half-lives in the tumours were 30±7 h. The activity distribution and penetration into tumour tissue were not affected by increasing the injected activity. There was a positive correlation between BLMC uptake and Ki-67/Mib activity as well as number of mitoses in tumour tissue. These data indicate that¹¹¹In-BLMC has potential as a radiochemotherapeutic agent in head and neck cancer and that adjuvant Auger-electron therapy is possible using^114m-In-labelled BLMC.