Treatment with monoclonal antibody to a Lewis lung carcinoma-associated antigen: different effects on primary tumor and its metastases.

The growth and dissemination of Lewis lung carcinoma have been analyzed following treatment of isolated tumor cells or of tumor-bearing animals with monoclonal antibody (MoAb) 135-13C, which recognizes a cell surface tumor-associated protein of 180,000 daltons. The results of this study indicate that MoAb 135-13C binds with high affinity to Lewis lung tumor cells and induces different effects on the primary tumor (20%-25% reduction of tumor weight) and its metastasis (twofold increase of lung nodule formation). Different schedules of MoAb 135-13C administration have shown that these effects are dose- and time-dependent. In particular, the maximum increase in metastasis formation is observed when the MoAb 135-13C is administered at time of systemic tumor dissemination. In vitro preincubation of tumor cells with MoAb prior to their iv injection into normal animals results in a significant increase of pulmonary metastatic nodules.