Synonyms :
6,9-bis[(2-aminoethyl)amino]benzo[g]isoquinoline-5,10-dione, BBR 2778, PIX

Status : investigational


Antineoplastic Agents

Therapeutic Classification


Topoisomerase II Inhibitors


Pixantrone is an aza-anthracenedione and DNA intercalator which inhibits topoisomerase II. It is similar in structure to anthracyclines such as mitoxantrone, but exerts fewer toxic effects on cardiac tissue. [2] The lower cardio-toxic effects of pixantrone may be explained, in part, by its redox inactivity [3]. Pixantrone does not bind iron and promotes the formation of reactive oxygen species to a lesser degree than other anthracyclines. It also inhibits doxorubicinol formation in human myocardium. [3] As a result, it is believed to be less cardiotoxic while still exerting efficacy. Pixantrone was designed to treat relapsed or refractory aggressive non-Hodgkin’s lymphoma(NHL) in patients who have failed two prior lines of therapy. [2] For patients suffering from NHL, first line therapies consist of anthracycline containing multi-drug treatments which unfortunately are known to cause irreversible myocardial tissue damage. Patients refractory to treatment, or those who relapse, are discouraged from further anthracycline use due to cumulative cardiotoxicity. Pixantrone dimaleate, administered intravenously, was designed by Cell Therapeutics Incorporated as an alternative second line therapy in refractory or relapsed NHL. It is currently being tested in Phase III trials. [2] Although pixantrone has not yet received FDA approval in the United States, it has been granted conditional marketing approval by the European Union. Conditional approval was granted by the European Medicines Agency after a phase III EXTEND trial of patients with NHL showed that pixantrone was tolerable and that it resulted in significantly higher complete response rate and progression free survival in comparison to other single chemotherapy agents. However, it is notable that the EXTEND trial was stopped early, leaving the statistical significance of the results in question. Based on this uncertainty, in 2009, the FDA ultimately rejected Cell Therapeutic’s initial application for accelerated approval for pixantrone use in relapsed or refractory NHL. Another phase III trial, PIX-R, is now ongoing to clarify pixantrones place in therapy. It will compare pixantrone efficacy to that of gemcitabine. [2]


Currently in Phase III investigation for treatment of relapsed or refractory aggressive non-Hodgkin’s lymphoma in patients who have failed two prior lines of therapy. Presently, no standard therapy exists for patients with relapsed or refractory NHL. [2] After first line therapy has been initiated, most patients have received their lifetime limit of doxorubicin and further use of anthracyclines may potentially lead to anthracycline-induced congestive heart failure (CHF). Pixantrone is an attractive alternative as a second line agent, due to its lack of cardiac toxicity. [2] The phase III trial, PIX-R, is ongoing and will compare pixantrone multidrug therapy with an equivalent regimen in patients with diffuse large B-cell lymphoma (the most common type of NHL). Previous study results have also suggested the possibility that pixantrone may be safe and effective in doxorubicin naive patients. In myocardial strips which are doxorubicin naive, pixantrone is taken up to a higher degree than in myocardial strips which are doxorubicin exposed, and once absorbed exhibits redox inactivity. [3] Pixantrone dimaleate has also been investigated as a treatment for acute myelogenous leukemia, diffuse large B-cell lymphoma, follicular lymphoma, metastatic breast cancer, low grade small lymphocytic lymphomas and general metastatic cancers.

Mechanism Of Action

Pixantrone is an aza-anthracenedione which acts as a DNA intercalator. By intercalating between DNA, with modest affinity, it stimulates DNA cleavage by topoisomerase II. (Pixantrone acts as a poison to topoisomerase II by stabilizing protein-DNA complexes which are usually transient, giving rise to double stranded DNA breaks.) However, pixantrone is believed to have additional mechanisms of action as its potency does not correlate to the degree of double stranded DNA breaks observed. It has been postulated that this second mechanism may be pixantrone-DNA adduct formation. [1] It is important to note that the formation of a pixtantrone-DNA adduct requires pixantrone activation by formaldehyde. Formadehyde may be generated in vitro by hydrogen peroxide, and is derived by various sources in biological systems. It is present in low levels as a result of normal metabolism, and may be present in elevated levels in some haematolgical malignancies. [1] The formation of pixantrone-DNA adducts is thus feasible, and it is believed that a long pixantrone-DNA adduct half life has the potential to maximize DNA damage. It may do so by enhancing the disruption of DNA replication and transcription, and potentially by encourage apoptosis. [1] In explanation of pixantrones lack of cardiotoxicity, it has been elucidated that pixantrone is structurally similar to mitoxantrone; however, instead of a 5,8-dihydroxyphenyl ring (thought to be responsible for cardiotoxicity) it has a nitrogen heteroatom. This nitrogen heteroatom helps to create additional hydrogen bonding sites amd increases pixantrone interaction with DNA and topoisomerase II. [2] Pixantrone’s lack of a hydroquinone is believed to render it resistant to one electron reduction. In contrast, doxorubicin – which contains a hydroquinone – experiences one electron redox cycling and ROS formation via NADH dehydrogenase. [3] Pixantrone also does not bind iron, and thus does not produce ROS by redox cycling between oxidative states of iron, as other anthracyclines do. [2] The first line agent doxorubicin is cardiotoxic, in part, due to its ability to redox activate the superoxide anion and hydrogen peroxide, and form a long-lived secondary alcohol metabolite: doxorubicinol. [3] Clearance of doxorubicin from myocardial tissue is incomplete, and it can be found months or years after the last administration. [3] In doxorubicin treated ex vivo cardiac strips, pixantrone formed an N-dealkylated product that inhibited metabolism of residual doxorubicin into doxorubicinol. Additionally, in ex vivo human myocardial strips (doxorubicin naive, and doxorubicin pretreated) pixantrone showed high cardiac uptake without formation of superoxide anion or hydrogen peroxide. Pixantrones lack of cardiotoxicity is thus attributed to its redox inactivity and inhibition of doxorubicinol formation. [3]


Pixantrone has a wide range of antitumor activity, especially in terms of treating leukemias and lymphomas [3].

Pixantrone lacks cardio-toxic effects. It has postulated that his is because of its redox inactivity and lack and inhibition of doxorubicinol formation in human myocardium. [3]

Toxic Effect

Pixantrone appears well tolerated. The most common toxicity is neutropenia. Other toxicities include lymphopenia, thrombocytopenia, alopecia, nausea and vomiting. As pixantrone is a blue compound patients may experience a blue discoloration of the skin and urine. [2]


Pixantrone does not form secondary alcohol metabolites. [2] Pixantrone hydrolyzes extensively to CT-45886 which is believed to inhibit doxol formation by displacing DOX from the active site of reductases. CT4889 and CT-45890 are also formed.[3]


Intravenous administration results in a rapid distribution followed by a slow elimination. [2] In ex vivo myocardial strips, pixantrone is taken up to a higher degree than mitoxantrone. In myocardial strips which are doxorubicin naive pixantrone displays higher uptake than in DOX-loaded myocardial strips. DOX clearance causes membrane effects which may be responsible for this observation. DOX clearance involves rapid passive diffusion through one side of the membrane followed by “flip flop” reorientation of the lipid bilayer. This disorganization of lipids is believed to impair membrane penetration by pixantrone. [3]

Half Life

Half life is 12 hours. [2]

Protein Binding

Anthracyclines, which may be effective second line treatments for NHL have limited use in therapy because of cumulative cardiotoxicity which may result in irreversible damage to cardiac tissue. [2]

Elimination Route

Fecally and renally excreted. Urinary elimination of unchanged drug is less than 10%. [2]


Plasma clearance is 0.75 – 1.31 L/h/kg. [2]

Volume of Distribution

9.7-29.7 L/kg. [2]

Chemical Classification

Salt : Pixantrone dimaleate

Chemical Name


Calculated Property

kind Value Source