The use of protein as a carrier of methotrexate for experimental cancer chemotherapy. II. Chemotherapy of Gardner lymphosarcoma with pea seed lectin-methotrexate derivative.

It was demonstrated that the tumorigenicity of tumor cells preincubated in low concentration of free methotrexate (MTX) has not been changed. On the other hand the preincubation of these cells with pea seed lectin (PL), MTX and PL mixture and especially pea seed lectin-methotrexate derivative (PL-MTX) influenced markedly the tumor cells tumorigenicity. The chemotherapy of Gardner lymphosarcoma (LSG) bearing mice with PL-MTX derivative was performed. After one dose therapy of LSG ascitic form with PL alone no effect on mice survival time was observed. The administration of PL-MTX derivative was efficient at a higher dose only. But free MTX was effective at both examined doses. Four times repeated injection of lectin to mice bearing the ascitic form of LSG shortened the survival time of mice. Repeated application of the higher dose of free MTX was accompanied with a considerable number of toxic deaths, but the life span of most surviving animals was prolonged. The similar but less expressive result has been reached by using PL-MTX derivative. The post mortem examinations suggest that the marked local inflammatory reactions are probably caused by the PL cytotoxicity. Therapy of solid LSG bearing mice with four i.t. injections of PL had no obvious effect on the survival. PL-MTX derivative prolonged distinctly the life span of tumored mice but the administration of sole MTX was the best.