Tetrathiomolybdate protects against cardiac damage by doxorubicin in mice

Cardiac toxicity is the limiting factor in therapy with doxorubicin, an otherwise useful cancer drug. In this article we detail our study of a mouse model of doxorubicin-induced cardiac toxicity in which, after 4 days’ treatment, doxorubicin caused marked increases in plasma concentrations of creatine kinase, lactic dehydrogenase, and troponin I, indicators of cardiac injury; marked increases in the plasma concentrations of tumor necrosis factor-α and interleukin-1β, both inflammatory cytokines; and a marked increase in the plasma concentration of interleukin-2, an indicator of cytotoxic T-cell activation. Therapy with tetrathiomolybdate, designed to limit copper availability, eliminated almost all of the increases of these six parameters in plasma. The marked protection against cardiac injury by doxorubicin in tetrathiomolybdate-treated animals suggests that tetrathiomolybdate would be of use clinically in helping prevent doxorubicin toxicity in patients. In other preclinical work, it has been shown that tetrathiomolybdate potentiates the chemotherapeutic effect of doxorubicin in cancer, so a double benefit might accrue clinically from the combined use of tetrathiomolybdate and doxorubicin. The mechanism by which tetrathiomolybdate protects against doxorubicin toxicity is of considerable interest. Our working hypothesis, based on the inhibition of interleukin-2 by tetrathiomolybdate as shown here, is that tetrathiomolybdate interrupts the inflammatory cascade at the activated–T-lymphocyte stage. Cardiac toxicity is the limiting factor in therapy with doxorubicin, an otherwise useful cancer drug. In this article we detail our study of a mouse model of doxorubicin-induced cardiac toxicity in which, after 4 days’ treatment, doxorubicin caused marked increases in plasma concentrations of creatine kinase, lactic dehydrogenase, and troponin I, indicators of cardiac injury; marked increases in the plasma concentrations of tumor necrosis factor-α and interleukin-1β, both inflammatory cytokines; and a marked increase in the plasma concentration of interleukin-2, an indicator of cytotoxic T-cell activation. Therapy with tetrathiomolybdate, designed to limit copper availability, eliminated almost all of the increases of these six parameters in plasma. The marked protection against cardiac injury by doxorubicin in tetrathiomolybdate-treated animals suggests that tetrathiomolybdate would be of use clinically in helping prevent doxorubicin toxicity in patients. In other preclinical work, it has been shown that tetrathiomolybdate potentiates the chemotherapeutic effect of doxorubicin in cancer, so a double benefit might accrue clinically from the combined use of tetrathiomolybdate and doxorubicin. The mechanism by which tetrathiomolybdate protects against doxorubicin toxicity is of considerable interest. Our working hypothesis, based on the inhibition of interleukin-2 by tetrathiomolybdate as shown here, is that tetrathiomolybdate interrupts the inflammatory cascade at the activated–T-lymphocyte stage.