Mitoxantrone-Iron Oxide Biodistribution in Blood, Tumor, Spleen, and Liver—Magnetic Nanoparticles in Cancer Treatment

BackgroundMagnetic drug targeting is a new treatment principle for tumors using cytostatics coupled to ferrogmagnetic nanoparticles and extracorporeal magnets. Higher concentrations in tumor tissue with lower systemic concentrations and without damage of healthy organs should be achieved.Materials and Methodsn = 42 adult Wag/Rij rats were transfected with rhabdomyosarcoma R1H 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.ResultsMitoxantrone 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.ConclusionsWe showed that magnetic drug targeting achieves higher concentrations of cytostatics in tumor tissue compared with blood. During magnetic drug targeting, iron particles are quickly sluiced and kept in the tumor area. Organs of the reticuloendothelial system are not affected by cytostatic damage.