Something Old, New, Borrowed, Blue: Anthracenedione Agents for Treatment of Multiple Sclerosis.

OBJECTIVE: This study aimed to present anthracenedione agents that have been used to treat multiple sclerosis (MS), problems related to their use, and knowledge gained from our experiences using these agents to develop more efficacious drugs with fewer adverse effects. METHODS: We review preclinical and clinical data during the development mitoxantrone, an anthracycline, for the treatment of MS; benefits and potential risks; and strategies to reduce complications of anthracyclines. RESULTS: Mitoxantrone had unacceptable and greater-than-anticipated toxicity for use in a chronic disease such as MS. Adverse effects included cardiotoxicity, treatment-associated leukemia, and amenorrhea. Toxicity was identified primarily in retrospect. Structurally related compounds include pixantrone (BBR2278) and BBR3378. Pixantrone is in clinical development in oncology. BBR3378 prevents the development of autoimmunity and experimental autoimmune encephalomyelitis and blocks experimental autoimmune encephalomyelitis even when given after the onset of autoimmunity. CONCLUSIONS: There remains a need for effective MS treatment, particularly for nonrelapsing forms of MS. Mitoxantrone was the first nonbiologic drug approved by the Food and Drug Administration for use in MS. Chromophore modification of anthracenedione agents yielded a novel class of DNA binding agents (aza-anthracenediones such as pixantrone and aza-anthrapyrazoles such as BBR3378) with the potential for less cardiotoxicity compared with mitoxantrone. There is a need for long-term observation for delayed toxicity among humans enrolled in pixantrone trials. Preclinical toxicity studies for delayed toxicities in rodents and other models are warranted before consideration of derivatives of anthracenediones, aza-anthrazenediones, or aza-anthrapyrazoles for use in human MS clinical trials.

A novel aza-anthrapyrazole blocks the progression of experimental autoimmune encephalomyelitis after the priming of autoimmunity.

Mitoxantrone is one of the few FDA-approved drugs available to treat rapidly progressing forms of multiple sclerosis; however, its utilization is compromised by a cardiotoxic potential and the risk of mitoxantrone-induced leukemia. BBR3378, a novel aza-anthrapyrazole, is structurally similar to mitoxantrone, but lacks the ring hydroxyls that may contribute to cardiotoxicity. Here, we investigated the therapeutic activity of BBR3378 in a C57BL/6 mouse model of multiple sclerosis. Mice given BBR3378, before or after the priming and expansion of MOG-specific responses, were protected from ascending paralysis. Strikingly, two doses of BBR3378 given a week after EAE induction were sufficient to provide significant protection from clinical symptoms and reduce MOG-specific proinflammatory T cell cytokine production, and serum IgG responses. Furthermore, while mitoxantrone is associated with persistent lymphopenia and cardiotoxicity, no such outcomes were detected in BBR3378-treated mice. Our findings show that BBR3378 can ameliorate encephalitogenic mechanisms in EAE and antagonize underlying autoimmune mechanisms.

Hypoxia activated prodrugs of a 9-aza-anthrapyrazole derivative that has promising anticancer activity.

Mono- and bis-N-oxides of a 9-aza-anthrapyrazole derivative having two 2-(dimethylamino)ethyl appendages were prepared by using a mild oxaziridine reagent. Biochemical and cell culture assays indicate that the bis-oxide is an inactive prodrug that readily converts to the active parent molecule under hypoxic conditions that are analogous to those present within certain tumors.

Verapamil, but not probenecid, co-administration can convert desloratadine to a sedating antihistamine in mice.

The possibility that non-sedating antihistamines could elicit sedation in mice due to drug-induced inhibition of brain PgP was evaluated by measuring the ability of desloratadine alone or in combination with verapamil to cause ataxia in mice. Also, the concentrations of desloratadine in plasma and in brain homogenates were measured by liquid chromatography-mass spectrometry. Relative to methylcellulose (control) treatment, verapamil plus desloratadine decreased rotarod performance of mice. Plasma concentrations of desloratadine appeared comparable in the mice treated with either desloratadine or verapamil plus desloratadine, however the rate of decline of desloratadine from brain tissue was slower in mice treated with verapamil plus desloratadine compared to mice treated with desloratadine only. These data suggest that inhibition of brain PgP can convert desloratadine to a sedating antihistamine in mice.

The hemodynamic effects of diaspirin cross-linked hemoglobin in dopamine-resistant endotoxic shock in swine.

As the blood substitute Diaspirin Cross-linked Hemoglobin (DCLHb) has potent vasopressor activity, we assessed its hemodynamic effects in a clinically relevant dopamine-resistant endotoxic shock model in swine. In a randomized and controlled study, E. coli LPS was administered to anesthetized and invasively monitored swine. Group I (n = 3) control pigs were not resuscitated. Groups II (n = 5) and III (n = 6) pigs received dopamine (DA) after MAP decreased 30%, and hetastarch and DCLHb, respectively, after dopamine-resistance occurred. Progressive hemodynamic decline occurred in Group I pigs. DA failed to restore MAP to baseline. However, 0% and 67% of pigs also treated with heta-starch and DCLHb, respectively, achieved temporary restoration of baseline MAP (p = 0.03), prompting a reduction in the dose of DA in 0% of hetastarch vs. 50% of DCLHb treated pigs. Except for increased MPAP and decreased heart in DCLHb treated pigs (p<0.001), hemodynamics and survival were not different (p>0.05). In conclusion, although DCLHb exacerbated pulmonary hypertension and did not improve O2 utilization or survival, because DCLHb restored MAP to baseline and had a dopamine sparing effect, further investigation of DCLHb's hemodynamic effects in adrenergic agent-resistant endotoxemia is warranted.

Characterization of anthracenediones and their photoaffinity analogs.

In an attempt to overcome the cardiotoxicity and cross-resistance problems caused by the anticancer drugs anthracyclines and anthracenediones during chemotherapy, we have developed a series of aza-anthracenedione compounds by modifying the chromophore and the side arms of anthracyclines and anthracenediones. One of these aza-anthracenediones, 6,9-bis[(2-aminoethyl)amino]benzo[g]isoquinoline-5,10-dione (BBR 2778), which is currently under phase II clinical trials, showed remarkable antitumor activity and appeared to lack a cardiotoxic effect in preclinical studies. However, it was still cross-resistant against multidrug resistance (MDR) cells expressing P-glycoprotein (P-gp). In contrast, another aza-anthracenedione, 6,9-bis[[2-(dimethylamino)ethyl]amino]benzo[g]isoquinoline-5,10-dione, which has side arm structures different from those of BBR 2778, was highly active against MDR cells. In this study, BBR 2778, BBR 2378, and an anthracenedione compound, 1,4-bis[(2-aminoethyl)amino]-5,8-dimethyl-9,10-anthracenedione, were used to assess the relationship between the chemical structures of these drugs and their interactions with DNA and P-gp. In addition, the biological and pharmacological influences of photoaffinity labeling were also studied for BBR 2778 and DEH. As the results indicate, the photolabeled analogs of BBR 2778 and DEH were less DNA-reactive and less cytotoxic. The more lipophilic compound, BBR 2378, and the photolabeled analogs of BBR 2778 and DEH inhibited P-gp labeling by azidopine better than did the more hydrophilic parental compounds. These studies suggested that the DNA binding affinity of BBR 2778 and DEH could be important in determining their cytotoxicity, and that the chemical structure of the side arms and the lipophilicity of these drugs are critical in determining their cross-resistance.