Anthracyclines Dr. VARUN GOEL

MEDICAL ONCOLOGISTRAJIV GANDHI CANCER INSTITUTE, DELHI

• In the 1950s, simultaneous efforts by French and Italian researchers led to the development of Daunorubicin.

• Daunorubicin was the first of the anthracyclines developed.

• Formed by the fermentation products of bacterium Streptomyces peucetius var. caesius and was originally described as antitumor antibiotic.

History

• The large and growing family of Anthracyclines now includes over 2,000 known analogs.

• Derivatives of clinical use are:– Daunorubicin (Cerubidine, Daunomycin,

Rubidomycin– Doxorubicin (Adriamycin, Rubex)– Epirubicin (Ellence, Farmorubicin(e), Farmorubicina,

Pharmorubicin).– Idarubicin (Idamycin, Zavedos)– Amrubicin (Calced)– Esorubicin– Aclarubicin (Aclacinomycin)– Pirarubicin.– Valrubicin (Valstar)

Anthracyclines - Varieties and Derivatives

• These compounds consist of: – Planar Hydrophobic tetracycline ring– Daunosamine sugar linked through a glycosidic

linkage. • All drugs are positively charged at

physiologic pH, favoring intercalation into DNA.

• Anthracyclines possess Quinone moieties on adjacent rings : Allow them to participate in electron transfer reactions and generate oxygen free radicals.

Structure

• Daunomycin and doxorubicin differ only by a single hydroxyl at position C14, yet have distinct spectra of antitumor activity.

• Idarubicin is a semisynthetic derivative of daunomycin (4-demethoxydaunorubicin) lacking the 4-methoxy group present on the parent compound.

• Epirubicin is an epimer of doxorubicin having the C4′ hydroxyl group on the amino sugar in the equatorial rather than the axial position. This increases lipophilicity compared with doxorubicin.

• Cell cycle nonspecific (predominant action on G2/S phase) of cell cycle.

• Various mechanisms are implicated for its cytotoxicity:– DNA intercalation.– Inhibition of topoisomerase II– Formation of cytotoxic oxygen free radical.

Mechanism of Action

• Intracellular drug concentrated in the nucleus • Anthracycline in the nucleus is intercalated into

the DNA double helix.• The consensus sequence for highest

doxorubicin affinity is 5´-TCA.• It is the planar ring, which actually intercalates

into DNA and the side chain provides an important hydrogen-bonding function.

• Intercalation prevents replication of rapidly growing cancer cells

DNA INTERCALATION

DNA INTERCALATION

• DNA topoisomerases are a general class of enzymes that alter the topology of DNA.

• Found in all organisms, including Archaebacteria, viruses, yeast, Drosophila, and humans.

• Access to DNA during processes such as replication, transcription, and recombination requires double-helical DNA to be separated, resulting in torsional stress.

• There are two general classes of topoisomerases; type I and type II, distinguished by the number of DNA strand breaks they make during catalysis.

Topoisomerase Enzyme

• Top1 is important in supporting replication fork movement during DNA replication and to relax supercoils generated during transcription.

• Top2 is responsible for: – unlinking intertwined daughter duplexes during DNA

replication– contributes to DNA relaxation during transcription – facilitates remodeling of chromatin structure.

• Type II topoisomerase enzymes function as homo- or heterodimers and require adenosine triphosphate for catalysis.

• A Topoisomerase dimer binds to DNA, forming a double-strand DNA break in which the proteins are covalently bound to the 5´ end of broken DNA strands to form the Top2 cleavable complex.

• Forms a gate in the DNA through which a second DNA double-helix strand can pass in an energy-dependent fashion.

• Anthracyclines poison Top2 by stabilizing the DNA-Top2 cleavable complexes, leading to DNA double-strand breaks

• Main mechanism of generating O2 Free Radical is one-electron reduction of the Anthracyclines’ quinone side rings.

• Catalyzed by Flavin-centered dehydrogenases, including cytochrome P-450 reductase, NADH dehydrogenase (complex I of the mitochondrial electron transport chain), xanthine oxidase, and cytochrome B5 reductase.

• Cause widespread damage to intracellular macromolecules, including lipid membranes, DNA bases, and thiol-containing transport proteins.

Formation of O2 Free Radical

One Electron Reduction

P450 reductase

02

• Resistance to topoisomerase-targeting drugs can involve alterations in

• drug accumulation, • Increased expression of the multidrug –resistant(MDR)

gene with elevated P-170 levels leading to drug efflux

• Decreased expression of Topoisomerase II.• Mutation in Topoisomerase II with decreased

binding affinity to drug.• Increased expression of sulphydryl proteins

including glutathione reductase.

MECHANISM OF DRUG RESISTANCE

Drug Duanorubicin Doxorubicin Epirubicin Idarubicin Protein binding

60-70% 60-70% 80% 70-80%

CSF/plasma ratio

Very low Very low Very low low

T1/2: ά γ

40 min.20-50 hr

10 min 30 hr

18.3hr21.1hr

11.3hr40-60hr

Metabolism Daunorubicinol,7-deoxyaglycone

Doxorubicinol (MC), 7-deoxyaglycone

Glucuronides of parent compd.

13-idarubicinol

Excretion Biliary (70%), Renal(<20%)

Biliary (50%), Renal (<10%)

Biliary (60-70%), renal (20%)

80% renal

Toxicity Myelosuppression,mucositis, aloplecia,cardiac toxicity, vesicant

Myelosuppression,mucositis, aloplecia,cardiac toxicity, vesicant

LeukopeniaThrombocytopenia, cardiotoxicity(=doxorubicin)

LeukopeniaThrombocytopenia, cardiotoxicity(<doxorubicin)

Route of administration

Intravenous (i.v.) i.v. i.v. i.v., oral(30%)

Drug FDA Indication Usual Dose Dose AdjustmentsDoxorubicin ALL

AMLCLLKaposi's sarcoma, Non-Hodgkin's lymphoma, Mantle cell lymphomaMycosis fungoides, Hodgkin's lymphoma, Gastric, Ewing's sarcomaProstate, ThyroidNephroblastomaNeuroblastomaNon-small cell lungOvarianTransitional cell bladder

40-60 mg/m2 every 3-4 weeksor60-75 mg/m2 every 3 weeks

Hepatic dysfunction

  Cervical 30 mg/m2    Langerhans' cell 50 mg on days 1 and 22 every 42 days  

  Multiple myeloma 9 mg/m2 continuous infusion days 1 to 4  

Liposomal doxorubicin

Kaposi's sarcomaOvarian

20 mg/m2 every 3 weeks50 mg/m2 every 4 weeks

Hepatic dysfunction

Daunorubicin ALLAML

30-45 mg/m2 daily for 3 days Renal or hepatic dysfunction

Epirubicin Breast 100-120 mg/m2 every 3-4 weeksor60 mg/m2 weekly for 2 weeks followed by 1-2 weeks rest

Hepatic or renal dysfunction

Idarubicin AML 10-12 mg/m2 daily for 2-3 days Hepatic or renal dysfunction

Amrubicin, a fully synthetic 9-amino anthracycline, is approved and marketed in Japan for the treatment of lung cancer. A recent randomized phase 2 study found that amrubicin was superior to topotecan in 60 relapsed small cell lung cancer patients in terms of response rates.

Additional anthracyclines are in clinical development including aclarubicin, valrubicin, and zorubicin. All appear to share a similar mechanism of action in terms of topoisomerase 2 poisoning.

Duanorubicin Doxorubicin Epirubicin Idarubicin

Dexa, 5-FU , Heparin : concurrent use precipitate formation.

Dexa, 5-FU , Heparin : concurrent use precipitate formation.

Heparin : concurrent use precipitate formation.

Heparin : concurrent use precipitate formation.

Cyclophosphamide: H’ghic cystitis, Cardiotoxicity

Cyclophosphamide:↑myelosuppression

Probenecid : ↑ risk of uric acid nephropathy

Phenytoin, gardenal: ↑clearance

Cimetidine ↓ AUC by 50%

Digoxin : decreases bioavail.

6-MP: ↑hepatotoxicity

Drug Interaction

toxicity profile

• Common side effect in all Anthracyclines.• Special considerations are necessary• Chronic cardiotoxicity is the most common type

of anthracycline damage.• The prevalence of late subclinical cardiac damage

has been reported to be more than 57% at a median of 6.4 years after treatment among survivors of childhood cancers .

• The incidence of clinical heart failure as high as 16%, 0.9 to 4.8 years after treatment.

• Differences in study population, treatment protocols, and duration of follow-up could account for this wide variability

Ann Oncol 2002

Cardiotoxicity

Can be divided into:• Acute or Subacute: Heart damage that

develops immediately after the infusion of the drug or within a week of therapy.

• Early onset chronic progressive cardiotoxicity: a depression of myocardial function which occurs during the treatment or within the first year after treatment.

• Late onset chronic progressive cardiotoxicity: this occurs at least 1 year after the end of treatment.

• Acute doxorubicin cardiotoxicity is reversible but chronic is irreversible.

Clinical features

• Early Cardiotoxicity: Myocarditis-pericarditis.• Early cardiotoxicity is presumably related to

myocyte damage or death resulting in depressed left ventricular contractility.

• Chronic cardiotoxicity: Cardiomyopathy - -Myofibrillar loss -vacuolar degeneration and coalescence of the sarcotubular system related to

myocyte damage or death resulting in depressed left ventricular contractility & decreased left ventricular systolic function.

• Chronic cardiotoxicity peaks at 1 to 3 months, but can occur even years after therapy.

Myocardial damage occurs by several mechanisms, the most important is generation of reactive oxygen species during electron transfer from the semiquinone to quinone moieties of the anthracycline.

The generation of hydrogen peroxide and the peroxidation of myocardial lipids contribute to myocardial damage.

Endomyocardial biopsy is characterized by a predominant finding of multifocal areas of patchy and interstitial fibrosis (stellate scars) and occasional vacuolated myocardial cells (Adria cells).

Myocyte hypertrophy and degeneration, loss of cross-striations, and absence of myocarditis are also characteristic of this diagnosis.

Other suggested cardiotoxicity mechanisms include:

metabolism of ANT into more hydrophilic and cardiotoxic substances, which subsequently accumulate in cardiomyocytes

impaired expression of various important cardiac proteins

disruption of cellular and mitochondrial Ca2+ homeostasis

induction of mitochondrial DNA lesions disruption of mitochondrial bioenergetics degradation of myofilamental and cytoskeletal

proteins, including titin and dystrophin interference with various pro-survival kinases

predisposition to cardiac damage includes a previous history of heart disease, hypertension, radiation to the mediastinum, age younger than 4 years, prior use of anthracyclines or other cardiac toxins, and coadministration of other chemotherapy (e.g., paclitaxel, cyclophosphamide, or trastuzumab).

Sequential administration of paclitaxel followed by doxorubicin in breast cancer patients is associated with cardiomyopathy at total doxorubicin doses above 340 to 380 mg/m2, whereas the reverse sequence of drug administration did not yield the same systemic toxicities

The incidence of cardiomyopathy is related to both cumulative dose and schedule of administration.

Cardiac toxicity is best correlated with peak plasma concentration of the parent drug rather than with the AUC.

Greater cumulative doses of doxorubicin can be given to patients receiving low-dose continuous infusions than to those receiving higher-dose bolus injections every 3-4 weeks.

Incidence of Clinically Detectable Congestive Heart Failure as a Function of Cumulative Doxorubicin DoseCumulative Dose (mg/m2)

Incidence of Congestive Heart Failure (%)

<350 <1

550 7

600 15

700 30

Clinically detectable congestive heart failure when doxorubicin is given at doses of 40-75 mg/m2 as a bolus injection every 3-4 weeks. But when doxorubicin is given by a low-dose weekly regimen (10-20 mg/m2/wk) or by slow continuous infusion over 96 h, cumulative doses of more than 500 mg/m2 can be given.

Doses of epirubicin below 1,000 mg/m2 and daunorubicin below 550 mg/m2 are considered safe.

Doses of idarubicin below 290 mg/m2 do not produce clinical congestive heart failure despite changes in cardiac ejection.

RISK FACTORS EFFECTS

ABNORMAL CARDIAC FUNCTION INCREASE

CUMULATIVE DOSE INCREASE

AGE Children <5 yr increased risk

SEX FEMALE SEX INCREASED RISK

IRRADIATION INCREASE

ADDITIONAL TREATMENT Co T/t WITH CYCLO/PACLITAXEL/TRASTUZUMA

B/BLEOMYCIN

BLACK RACE INCREASE

TRISOMY21 INCREASE

LENGTH OF FOLLOW UP INCREASE

LENGTH OF INFUSION DECREASE

Risk factors for Cardiotoxicity

Strategies for reducing cardiotoxicity Efforts in this direction have so far focused

on:

Dose and formulation of the anthracyclines. Development of safe new derivatives. Simultaneous treatment with protective substances

thought to interact beneficially.

Liposomal formulations are said to promote tumor concentrations of the drug while exposing normal tissue to lower, at best non toxic levels.

They are also associated with higher rates of other toxic effects such as neutropenia

Furthermore, these formulations are extremely expensive and so far lack evidence on long term safety or harms.

Cardiotoxicity Reduction Strategy

Newer anthracyclines • tumor activated anthracycline "prodrugs” such as pirarubicin and valrubicin and N-L-

leucyl-doxorubicin. • unable to penetrate healthy cells, but are

activated and potentiated extracellularly by tumor secreted peptidases.

• Disaccharide derivatives of anthracyclines are known as third generation anthracyclines. The best known is sabarubicin or MEN 10755.(PH 2 trials)

Cardiotoxicity Reduction Strategy

The iron chelating agent dexrazoxane, reduce anthracycline induced oxygen radical production.

• Dexrazoxane(dex) is FDA approved to prevent anthracycline induced cardiotoxicity in women with metastatic breast cancer who have received a total cumulative dose of doxorubicin(dox) of 300 mg/m2 & would benefit from continued treatment.

• Recommended dose is to give dexrazoxane I.V. 30 minutes before doxorubicin at a ratio of dex:dox of 10:1.

CO-THERAPY with Protective Agents

• include the use of – angiotensin-converting enzyme (ACE) inhibitors– angiotensin II receptor blockers (ARBs)– carvedilol - has potent antioxidant and anti-

apoptotic properties.

New prevention strategies

• Important dose limiting toxicity .• Leucopenia more common than thrombocytopenia

and anemia.• Myelosuppression begins in 7 days following

administration. • Nadir occurs by day 10-14 followed by recovery by

day 21.• Thrombocytopenia and anemia less severe.• Daunorubicin : BM suppression > mucositis• Doxorubicin :BM suppression= mucositis.• Growth factor support often needed .• With weekly dosing or continuous infusion, mucositis

frequently becomes the dose-limiting toxicity.

Myelosuppression & Mucositis

• Extravasation of most anthracyclines leads to severe local injury that can continue to progress over weeks to months.

• The drug has been shown to bind locally to tissues

• Local wound care to prevent infection is most important.

• A wide range of treatments including ice, steroids, vitamin E, DMSO(dimethyl sulphoxide), and bicarbonate used.

• Recently cardioprotectant Dexrazoxane has been used to treat acute Anthracycline extravasations in combination with subcutaneous granulocyte-macrophage colony-stimulating factor to promote wound healing.

Extravasation injury

Nausea & vomiting. Hyperpigmentation of nails , urticaria. Aloplecia Red orange color of urine . Lasts 1-2 days

after drug administration. Erythema at injection site – flare reaction. RADIATION RECALL. increased

inflammation in previously irradiated areas can lead to pericarditis, pleuritis and skin rashes.

Other ADR’S

• RISK OF SECONDARY MALIGNANCY:• Anthracyclines are also known to

multiply the risk of developing acute myelogenous leukemia, a form of leukemia which is usually unresponsive to treatment and carries a poor prognosis.

• Overall absolute risk remains low (estimated at less than 2% at ten years after treatment)

JCO 2002

DELAYED EFFECTS OF ANTHRACYCLINES

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