Monoclonal antibody KS1/4-methotrexate immunoconjugate studies in non-small cell lung carcinoma.

The antigen reactive with murine monoclonal antibody (MAb) KS1/4 is expressed on epithelial malignancies and some normal epithelial tissues. Studies were undertaken to evaluate KS1/4-methotrexate (KS1/4-MTX) immunoconjugate in patients with advanced non-small cell carcinoma of the lung. Eleven patients in two different groups received KS1/4-MTX in two different escalating dose infusion schedules with a maximal tolerated dose of 1,750 mg/M2 and a cumulative dose of MTX of 40 mg/M2. Toxicities were similar in both groups and included fever, anorexia, nausea, vomiting, diarrhea, abdominal pain, guaiac positive stool, and hypoalbuminemia. Two patients had an associated aseptic meningitis. One patient had a 50% decrease in two lung nodules without a change in lymphangitic infiltrates. This patient received a second course of treatment and developed an immune complex-mediated arthritis and serum sickness. Four patients mounted a human antimouse antibody response. Post-treatment tumor biopsies documented binding of MAb KS1/4. These studies document the feasibility and potential usefulness of a MAb directed against tumor-associated antigens with the targeting of chemotherapeutic drugs in patients with non-small cell lung carcinoma.