melphalan and sodium-cyanate

Sodium cyanate is a selective inhibitor of protein synthesis in a variety of mammalian tumor cells without a corresponding effect on normal tissue of the tumor-bearing animals. In the present study, we investigated the potential role of sodium cyanate in the augmentation of the antitumor activity of melphalan in MOPC-460D myeloma-bearing BALB/c mice. The simultaneous intraperitoneal injection of sodium cyanate, 250 mg/kg, and melphalan, 12 mg/kg, followed by another dose of sodium cyanate, 200 mg/kg, administered 18 hours later, resulted in a tumor growth inhibition index (TGII) of 207%. In contrast, melphalan or sodium cyanate administered separately at the same dose induced a TGII of 133% and 15%, respectively, when compared to control animals. Furthermore, a direct comparison of the volume of tumor implants in mice treated with the combination of sodium cyanate and melphalan vs. those treated with melphalan alone showed a statistically significant growth inhibition in favor of the sodium cyanate and melphalan combination on days 35, 39, and 42 from initiation of treatment. The data presented here suggest that the antitumor activity of melphalan could be increased, with moderate toxicity, by the concomitant intraperitoneal administration of sodium cyanate in BALB/c mice bearing measurable subcutaneous MOPC-460D tumor transplants. This is the first report of an increase in melphalan antitumor activity by sodium cyanate at a tumor location distant from the site of injection.

Topics: Animals; Antineoplastic Combined Chemotherapy Protocols; Cyanates; Injections, Intraperitoneal; Male; Melphalan; Mice; Mice, Inbred BALB C; Multiple Myeloma; Protein Synthesis Inhibitors

Sodium cyanate (NaOCN) at a dose of 250 mg/kg was shown to decrease protein synthesis in P388 leukemia tumor cells to approximately 52% of control values at 2 h and 32% at 5 h after NaOCN administration, without a corresponding decrease in various normal tissues of the tumor-bearing CD2Fl mice. CD2Fl mice that had received P388 tumor cells IP 1 day prior to drug administration underwent various schedules of treatment with NaOCN and melphalan (MLN). NaOCN (200 mg/kg or 250 mg/kg) administered IP has no significant antitumor activity (increased mean lifespan [ILS] less than 20%). The simultaneous IP administration of NaOCN (250 mg/kg) plus MLN (15 mg/kg) resulted in a significantly greater antitumor activity (approximately 265% of control, with 21 of 30 animals being long-term survivors) than MLN (15 mg/kg) alone (approximately 156% of control, with 11 of 30 animals being long-term survivors). This synergism was not observed when MLN was administered 4 h after NaOCN administration. The synergistic activity of MLN with NaOCN does not appear to be secondary to alterations in the absorption from the peritoneal cavity into the systemic circulation as determined by 3H2O. NaOCN does not increase the intracellular concentration of [chloroethyl-14C]MLN into P388 cells. The mechanism of the synergistic antitumor activity of simultaneous IP administration of NaOCN and MLN is unknown.

Topics: Absorption; Animals; Body Water; Cyanates; Drug Interactions; Leukemia P388; Leukemia, Experimental; Life Expectancy; Male; Melphalan; Mice; Mice, Inbred BALB C; Neoplasms, Experimental