Assessment of Mitoxantrone-Induced Cardiotoxicity in Patients with Multiple Sclerosis: A Tissue Doppler Echocardiographic Analysis

Mitoxantrone, pixantrone and mitoxantrone (2-hydroxyethyl)piperazine are toll-like receptor 4 antagonists, inhibit NF-κB activation, and decrease TNF-alpha secretion in primary microglia

Toll-like receptor 4 (TLR4) recognizes various endogenous and microbial ligands and is an essential part in the innate immune system. TLR4 signaling initiates transcription factor NF-κB and production of proinflammatory cytokines. TLR4 contributes to the development or progression of various diseases including stroke, neuropathic pain, multiple sclerosis, rheumatoid arthritis and cancer, and better therapeutics are currently sought for these conditions. In this study, a library of 140 000 compounds was virtually screened and a resulting hit-list of 1000 compounds was tested using a cellular reporter system. The topoisomerase II inhibitor mitoxantrone and its analogues pixantrone and mitoxantrone (2-hydroxyethyl)piperazine were identified as inhibitors of TLR4 and NF-κB activation. Mitoxantrone was shown to bind directly to the TLR4, and pixantrone and mitoxantrone (2-hydroxyethyl)piperazine were shown to inhibit the production of proinflammatory cytokines such as tumor necrosis factor alpha (TNFα) in primary microglia. The inhibitory effect on NF-κB activation or on TNFα production was not mediated through cytotoxity at ≤ 1 µM concentration for pixantrone and mitoxantrone (2-hydroxyethyl)piperazine treated cells, as assessed by ATP counts. This study thus identifies a new mechanism of action for mitoxantrone, pixantrone, and mitoxantrone (2-hydroxyethyl)piperazine through the TLR4.

The current role of mitoxantrone in the treatment of multiple sclerosis

Mitoxantrone is an immunosuppressive drug approved for aggressive relapsing and progressive multiple sclerosis. In recent years, its use has decreased due to the risk of severe adverse events and the introduction of novel therapies, such as natalizumab or fingolimod. Mitoxantrone is effective in reducing inflammatory activity by decreasing the number of relapses and MRI lesions and simultaneously decreasing the worsening of disability. Apart from its role as a second/third-line therapy, some studies suggest its use as an induction therapy. However, mitoxantrone use is limited because of its potential risk of severe adverse events, such as cardiotoxicity and the induction of therapy-related acute leukemia. Genetic markers are on evaluation to predict side effects and therapeutic efficacy, which is consistent with the direction of personalized treatment. Considering its efficacy and the potential risks, mitoxantrone use is limited to active patients after a careful, individualized evaluation of the risk/benefit balance.

Serial Assessment of Cardiac Function during and following Mitoxantrone Infusion in 30 Consecutive Patients with Multiple Sclerosis

Immunosuppressive therapy is an established therapeutic option in patients suffering from multiple sclerosis (MS). In an open nonrandomized study we serially assessed cardiac function in 30 consecutive patients with MS before, during, and after mitoxantrone therapy. Mitoxantrone (12 mg/m(2)) was administered intravenously at 3-month intervals. Before each infusion, cardiac function was assessed by history taking, resting electrocardiogram, and echocardiography. Whereas no patient experienced clinical signs of heart failure, left ventricular pump function decreased continuously during mitoxantrone therapy and did not recover after cessation. The presented data suggest a dose-dependent and long-lasting toxic cardiac effect of low-dose mitoxantrone therapy in MS.