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Background: Magnetic drug targeting is a new treatment principle for tumors using cytostatics coupled to ferromagnetic nanoparticles and extracorporeal magnets. Higher concentrations in tumor tissue with lower systemic concentrations and without damage of healthy organs should be achieved., Materials and Methods: n = 42 adult Wag/Rij rats were transfected with rhabdomyosarcoma R(1)H in their right gastrocnemius muscle. In the biodistribution trial (n = 36) concentrations of mitoxantrone-iron oxide with and without an extracorporeal 0.6 tesla magnet and regular mitoxantrone were measured in plasma and tumor tissue for one- and two-dose administration. In the plasma iron trial (n = 6) iron concentrations were measured in plasma before, during, and up to 30 min after drug administration. Seven days after the trial liver, spleen and tumor samples were obtained and histologically assessed., Results: Mitoxantrone iron-oxide concentration in plasma was significantly (P < 0.05) lower when a magnet was placed over the tumor area and as low as uncoupled mitoxantrone. Mitoxantrone concentration in tumor tissue was always significantly higher with magnetic drug targeting when compared with uncoupled mitoxantrone. Two doses resulted in drug accumulation in tumor tissue. Plasma iron concentrations rose when the drug was first administered. Plasma levels fell below the starting level with a magnet applied. A rebound phenomenon with rising iron concentrations was observed after the magnet was removed. Tumors showed fresh necrosis and liver and spleen had detectable iron depositions but no necrosis 7 d after treatment. No allergies or toxic reactions were observed., Conclusions: We showed that magnetic drug targeting achieves higher concentrations of cytostatics in tumor tissue compared with blood. During magnetic drug targeting, iron particles are quickly sliced and kept in the tumor area. Organs of the reticuloendothelial system are not affected by cytostatic damage., (Copyright © 2012 Elsevier Inc. All rights reserved.)

Background: Magnetic drug targeting (MDT) is a new treatment principle for tumors. Passive MDT (pMDT) uses cytostatics coupled to ferromagnetic nanoparticles, whereas in active MDT (aMDT), extracorporeal magnets are additionally placed over the tumor area., Purpose: Mitoxantrone-magnetite-dextran composite particles were used to assess the distribution and effect of MDT., Methods: We conducted two trials with n = 60 rats transfected with R(1)H rhabdomyosarcoma cells. In the biodistribution trial (n = 36) mitoxantrone concentrations in tumor tissue versus plasma were measured after one or two dose administration for aMDT, pMDT, and uncoupled mitoxantrone. The dose/effect trial (n = 24) assessed change in tumor volume at day 1 and 7 days after administration of 4, 6, or 8 doses of mitoxantrone using aMDT., Results: Mitoxantrone-magnetite-dextran concentration in blood was significantly (p < 0.05) lower when using aMDT and as low as uncoupled mitoxantrone. Concentrations in tumor tissue were always significantly higher using MDT when compared to uncoupled mitoxantrone. Two doses resulted in drug accumulation inside the tumor. Tumor growth was significantly decreased with four doses using aMDT versus no treatment. Tumor size on day 8 versus day 1 was significantly (p < 0.05) reduced after administration of six doses of mitoxantrone-magnetite-dextran. No allergies/toxic reactions were observed., Conclusions: The MDT achieves higher levels of cytostatics in tumor tissue without increased systemic concentrations and succeeds in reducing tumor volume.