[Muramyl dipeptide derivative and its clinical application]

Muramyl dipeptide (MDP) and its synthetic derivatives which comes from the major constituent of bacterial cell wall has various biological activities as host defence mechanisms. One of the synthetic MDP derivatives, MDP-Lys (L 18), muroctasin has potent biological activities with less adverse reactions among various MDP derivatives. Muroctasin has proved to be safe to use clinically as the results of phase I clinical study. We attempted to evaluate its clinical usefulness and safety from the view point of restorative activity in leukopenia that was induced by cancer chemotherapy in patients with malignancies. It is concluded that muroctasin is effective as well as useful on the restorative activities against leukopenia in lung cancer patients after cancer chemotherapy, with the optimal daily dosage of 200 micrograms for six times by subcutaneous injections through phase II and phase III clinical cooperative studies in Japan. Supposed mode of action of muroctasin for granulocytosis may be the results of CSF production due to stimulation of macrophage by muroctasin. This first clinical success of restoration of leukopenia in patients with cancer receiving cancer chemotherapy by MDP derivative, muroctasin, might be not only advantageous for cancer chemotherapy and/or radiation therapy but also for preventing infections occurring in compromised host due to neutropenia in cancer patients by means of cytotoxic cancer chemotherapy or irradication.