Clinical experience with intra lymphatic administration of 111In-labelled monoclonal antibody PAY 276 for the detection of pelvic nodal metastases in prostatic carcinoma.

The ability of 111In-PAY 276 (anti prostatic acid phosphatase antibody) in detecting pelvic lymph node metastasis following bipedal intra lymphatic administration was studied in five patients with carcinoma of the prostate. The labeled antibody was injected directly into the lymphatics of each foot. Planar and tomographic images radioactivity content of lymph nodes resected during staging pelvic lymphadenectomy were compared to the histologic and immunoperoxidase findings. Radioactivity in pelvic lymph nodes was prominently seen within 20 min of injection and was present 16 days later. Persistent accumulation of tracer in the lymphatics of the lower extremities was also observed in all patients 16 days post injection. Radioactivity counts in tumor-free lymph nodes were higher than in tumored lymph nodes resected. Our results demonstrate that intra lymphatic administration of 111In-labeled PAY 276 monoclonal antibody has major technical limitations, and that further research directed at the causes of tracer accumulation in the lymphatics and tumor-free lymph nodes is required.