[Treatment with K-18 (IgG-melphalan) in recurrent cases of hematopoietic malignancies].
K 18, an IgG-Melphalan conjugate was administered to 30 patients, who had recurrent hematopoietic malignancy. Ten out of the 30 patients received single doses of 1 to 20 enteric tablets containing 10 mg of K 18, as a phase I study. No side effects were observed. K 18 was administered every day to the remaining 20 patients in order to evaluate the side effects and therapeutic effects, as a phase II study. One patient attained partial remission. Although no remission effect was obtained in 14 of the 20 patients, antitumor effects such as a decrease in leukemia cells, were observed in 4 of 20 patients. As to side effects, neither recurrence of tumor nor cumulative toxicity were shown in one patient with NHL who received only K 18 for 14 months as maintenance therapy. Evaluation of antitumor effect was difficult in the case of the remaining 4 patients. In the 20 cases who entered the phase II study, a decrease in neutrophils was observed in 2 patients, a slight decrease in platelets in 3 patients and increased transaminase activity in one patient as side effects of K 18. In brief, compared with Melphalan, K 18 has between 1.3 and 2 times a more potent therapeutic effect, with extremely low side effects.