CHEMOTHERAPEUTICS OF MALIGNANT DISEASES

A. Kohút

Carcinogenesis

DNA mutation

• hereditary

• acquired

radiation viruses chemicals drugs

Categories of genetic changes resulting in malignity

a) inactivation of tumor supressor genes:

• mutation• binding to a virus protein• binding to a mutated

cellular protein

b) activation of protooncogenes to oncogenes:

• point mutation

(single nucleotide polymorphisms-SNPs)

• gene amplification• chromosome

translocation• virus interaction

Oncogenes – autonomy of cell growth

Oncogenes interfere with:• mechanisms of proliferation• mechanisms of differentiation

by means of:• production secretion of autocrine

growth factors• receptors for growth factors• cytosolic nuclear signal pathways• transduction systems controling cell cycle

Characteristics of tumour cells

• uncontrolled proliferation

• dedifferentiation loss of function

• invasiveness

• metastatic potential

Therapeutic effect of anticancer drugs

a. The therapeutic effect of anticancer drugs may require total tumor cell kill, which is the of all neoplastic cells.

b. Achievement of a therapeutic effect often involvs drugs that have a narrow therapeutic index (TI).

c. A therapeutic effect is usually achieved by killing activelly growing cells, which are most sensitive to this class of agents.

d. Because normal cells and cancer cells have similar sensitivity to chemotherapeutic agents, adverse effects are mostly seen in normally dividing non-neoplastic cells, sach as:

hair follicles, bone marrow, sperm.e. To minimize the adverse effects and resistance, often is used

combination of several agents with different mechanism of action.

f. Achievement of a therapeutic effect may involve the use of drugs, sometimes sequentially (at specific stages of cell cycle).

                                                                                                                                                                                                                                                                                                      

                                                                                                          

„PRODRUGS“ 1. Cyclophosphamide 4-Hydroxyphosphamide (liver) 2. Procarbazíne dacarbazine (liver) 3. Merkaptopurine 6-merkaptopurine ribozophosphate 4. Tioquanín 6-tioquanín-ribózophosphate 5. Fluorouracil 5-fluoro-deoxy- uracil monophosphate 7. Mitomycin (only at the hypoxic tissue of tumors) 8. Doxorubicin idarubicin

SENSITIVITY OF TUMOURS TO CHEMOTHERAPY

• chemosensitive tumours

• intermediary chemosensitive

tumours

• chemoresistant tumours

Chemosensitive tumours

• generally sensitive to several drugs

• combined chemotherapy is prefered

• chemotherapy is always indicated

Intermediary chemosensitive tumours

• complete remission rate about 10%

• high partial response (about 50%)

• combined chemotherapy is slightly more effective

• chemotherapy could be used

(no as first-choice therapy)

Chemoresistant tumours

• low response rate (about 20%)

• complete remission is rare

• chemotherapy has only adjuvant role

• neoadjuvant therapy

Factors influencing chemotherapy response

• fraction of proliferating cells

• cell cycle rate

• synchronisation of cell cycle within tumour

• tumour mass large tumours are relatively less sensitive: 1. a lot of cells in G0 2. penetration of drugs

• kinetics of cell killing cytotoxic drugs kill only a part of cells of certain type

• resistance of tumour cells

Mechanisms of resistance I.• Defect activation

– cyclophosphamide needs metabolic activation – metothrexate needs conversion to MTX-

polyglutamate in cells

• Increased inactivation – sulfhydryl substances - glutathion, metalothionein – scavenge

reactive molecules– aldehyde dehydrogenase – inactivation of cyclophosphamide

• Increased nucleotide levels– can affect the effectiveness of antimetabolites

• Changes in DNA repare repare mechanisms, elimination of cross-links– bleomycine other DNA-interfering drugs

Mechanisms of resistance II.

• Changes in target structure – active enzyme with lower drug affinity:

DFR-metothrexate

• Reduced quantity of target structure amount of topo II: etoposide

• Gene amplification– metothrexate: DFR requires more MTX

to block the activity

Mechanisms of resistance III.

• Decreased accumulation

– Decreased uptake • MTX - protein transporter• melphalan/leucine transport

– Increased efflux • multidrug resistance (MDR):

- most often for natural drugs doxorubicine, etoposide, actinomycine D, vinca alcaloids

- Pgp is normally expressed in some cells, e.g. stem cells in bone marrow

Combination chemotherapy

• tumours have tendency to be resistant to some drug (cell heterogeneity)

• resistance is often required during therapy with only one drug (proliferation of mutated cells)

• several sites of effect are possible with drugs with different side effects

• cummulative biochemical damage appear in cancer cells

MODALITIES OF ANTICANCER CHEMOTHERAPY

1. Intermittent application• period for bone marrow regeneration• period for immunity regeneration

2. Continual therapy• during maintenance therapy (chlorambucil in CLL, busulfan in CML, hormones or

antagonists in prostate or breast carcinoma)

3. Special applications• instilation in malignant secretions (bleomycine, thiotepa) (can be palliative by volume reduction)• intrathecal (metothrexate) (infiltration of CNS in leukemia)

INDIVIDUALISATION OF CANCER THERAPY

Type of tumour:• selection of anticancer drug• combination (or not)

Repeated evaluation of clinical status:• continuation (or not) in agressive therapy

Continual monitoring of bone marrow:• before & during therapy• reduction (or not) of therapeutic regimen

intensity

The use of drugs modifying unwanted side effects:• antiemetics, colony-stimulating factors• increase in therapeutic:toxic ratio

PRACTICAL USE OF ANTICANCER DRUGS

• the doses are expressed in

mg per m2

of body surface

(more precise dose/effect ratio)

Toxic effects of anticancer chemotherapeutics

• myelotoxicity• alopecia • loss of appetite &

weight• nausea & vomitus• taste change• stomatitis,

esophagitis, constipation, diarrhea

• fatigue

• cardiotoxicity• neurotoxicity• lung damage• sterility &

teratogenicity• hepatotoxicity &

nefrotoxicity• ↓ wound healing • ↓ growth (children)• carcinogenicity

ANTICANCER DRUGS

Mechanism of action - cell cycle

• intercalation• blockade of metabolic

steps in DNA synthesis

of enzymes regulating cell cycle

RNA synthesis protein synthesis microtubular

functions

Cell cycle intervals & anticancer drugs interferrence

Anticancer drugs

1. alkylating agents (cyclophosphamide, cisplatin)2. antimetabolites (methotrexate)3. cytotoxic ATB (antracyclines)4. mitosis inhibitors (vincristine, taxans)5. topo inhibitors (topotecan, etoposide) 6. hormones (corticoids, tamoxifen, flutamide)7. enzymes & other drugs (asparaginase,

procarbazine, hydroxyurea)8. PTK inhibitors (imatinib)9. monoclonal antibodies

(rituximab,trastuzumab)

I. Alkylating agents

• cyclophosphamide• platinum derivatives• derivatives of nitrosourea (lomustine,

carmustine)• estramustin• melphalan• chlorambucil• busulphan• dacarbazine

Mechanism of action

• inter- or intra-chain cross-linking

• interference with transcription & replication (S phase & G2 block)

• apoptosis

Alkylating agents

Side effects

• myelosuppresion

• GIT toxicity

• inhibition of gametogenesis (sterility-males)

• secondary malignities (acute leukemias)

Cyclophosphamide(mustard gas)

• frequently used

• also as immunosupressive agent

• P-450 activation

• p.o., i.v, i.m.

• derivative - ifosfamide

Cyclophosphamide

Side effects

• myelosuppression

• GIT toxicity

• hemorrhagic cystitis – acroleine

N-acetylcyst., mesna

Cisplatin, carboplatin

• platinum complex

2 chlorid ions

2 amonium groups

• cross-linking,

DNA denaturation

• solid tumors - testes & ovarial

Cisplatin

Kinetics slow i.v. perfusion

(water soluble)

Side effects • myelosuppression

• GIT toxicity• nephrotoxicity• emetogenity • ototoxicity

• neuropathies

II. Antimetabolites

• Antagonists of folic acid

• Pyrimidine derivatives (thymine, cytosine, uracil)

DNA RNA

• Purine derivatives (adenine, guanine)

Methothrexate(antifolate)

Mechanism of action

• folates – purine nucleotides – thymidilate – DNA

• reduction to FH4

• DHFR - high affinitt for FH4 - key enzyme

• transport of monocarbon groups• uracile methylation to 2-deoxyuridylate

(DUMP) & thymidylate (DTMP)

• DNA synthesis

Methothrexate

Kinetics• low liposolubility• p.o., i.v., i.m., i.t.• folate transport (in the cell)

• polyglutamation (intracellular)

• higher affinity to DHFR as FH2

• FH4 depletion

Side effects• myelosuppression,

GIT, pneumonitis, nephrotoxicity (tubular precipitation - hydratation)

• high doses – followed by folic acid

Fluorouracil (5-FU)(pyrimidine (uracile) derivative)

Mechanism of action• interference with

thymidylate & DNA synthesis

• fluorodeoxyuridine monophosphate formation (FDUMP)

• parenteral application • mainly solid tumors

(GI)

Side effects• GI epithelial damage• myelotoxicity

Cytarabine (pyrimidine (cytidine) derivative)

Mechanism of action

• intracellular phosphorylation

• DNA & RNA incorporation

• DNA polymerase inhibition

• Inhibition of replication & reparation

Kinetics & indications

• s.c. (myelodysplastic syndrome), i.v., i.t.

• AML, CML remission, lymphoma, myelodysplast. sy

Side effects• myelosuppression, GIT,

nausea, vomiting

III. Cytotoxic ATB

• Anthracyclines(daunorubicine, doxorubicine, epirubicine,

idarubicine)

• Bleomycines

Daunorubicine (anthracycline)

Mechanism of action

• intercalating ATB• topo II inhibition

Indications• induction therapy

ALL, AML,

CML blast. trans.

Kinetics• i.v. infusion

• metab. & excretion (mainly liver)

Side effects• myelotoxicity• accumulative cardio-

toxity (free radicals)

• alopecia • local necrosis

(extravascular appl.)

Doxorubicine (anthracycline)

Mechanism of action

• intercalating ATB • inhibition of topo II • much broader

indication spectrum as dau

• Hodgkin, NHL, myeloma, at least all localizations of solid tumors

• i.v. perfusion, intravesically

Side effects• myelotoxicity

• cardiotoxicity (dexrazoxan)

• alopecia, mucositis, necroses in mouth & if applied paravenously

Bleomycines(glycopeptide ATB-radiomimetic)

• Fe ion chelatation, interaction with O2

• superoxide & hydroxyl radicals

• degradation of preformed DNA

• chain fragmentation

• radiomimetic effect

• most effective in G2 & M phase, as well as G0

• testicular tumors & malignant lymphomas

• orofacial tumors, ca vulvae, penis, skin

• i.v., i.m.

Side effects• shivering, fever• lung fibrosis• allergies, mucocutaneous

reactions• low hemat. tox.

IV. Mitosis inhibitors

• Vinca alcaloids(vincristine, vinblastine, vinorelbine)

• Taxans(paclitaxel, docetaxel)

Mechanism of actionInhibition of polymerisation:

colchicin

vinca alcaloids

Tubuline Microtubulus

Stimulation of polymerisation Inhibition of depolymerisation

taxans

Vincristine (vinblastine, vinorelbine)

(mitosis inhibitors)

Mechanism of action• inhibition of tubuline polymerisation • inhibition of mitotic spindle

formation• effective in G2/M phase

Side effects• myelosuppression phagocytosis, chemotaxy of

leukocytes axonal transport in neurons• paresthesies, neuromuscular

abnormalities

Vincristine, vinblastine

Indications

Vincristine• ALL & AML• Hodgkin lymphoma, NHL• multiple myeloma• combination therapy in some solid tumors

Vinblastine• Hodgkin lymphoma, NHL• testicular tumors• choriocarcinoma• Grawitz tumor

Paclitaxel, docetaxel(mitosis inhibitors)

Mechanism of action

• microtubular stabilisation

• final effect like vinca alcaloids

Kinetics• very low water

solubility• only as i.v. perfusion

Paclitaxel, docetaxel

Side effects

• myelosuppression• neurotoxicity• hypersensitivity

(premedication with

steroids & antihistaminics)

Indications

• metastatic tumors (breast)

• progressive ovarial tumors

• NSCLC• Kaposi sarcoma (AIDS)

V. Topoisomerase inhibitors

• topo I inhibitors(topotecan, irinotecan)

• topo II inhibitors(etopozide, tenipozide)

Topotecan (irinotecan)(topo I inhibitors)

Mechanism of action• topo I inhibition• its levels are during

the whole cell cycle

Side effects• diarrhea, reversible

myelosuppression• relatively low toxicity

Indications

• metastatic ovarial tumors in case of first line therapy failure (topotecan)

• colorectal ca in progress (irinotecan)

Etopozide (tenipozide)(topo II inhibitors)

Mechanism of action• Inhibition of

mitochondrial functions & nucleoside transport

• topo II inhibition

Side effects • nausea, vomitus • myelosuppression,

alopecia

Indications • solid tumors

(lung-SCLC, testicular, trophoblast, ovarial, urinary blader)

• malignant lymphoma, acute non-lymphatic leukemia

VI. Hormones

• Glucocorticoids(prednisolone, dexamethasone)

• Antihormones(tamoxifen, flutamid)

Tamoxifen (toremifen)

Mechanism of action• nonsteroidal

antiestrogene

• inhibits estradiol binding to receptors

Indications• p.o. appl. in breast

cancer with positive estrogene receptors

Side effects

• metrorhagies• thrombophlebitis• flush• alopecia• estrogene

endometrial effect

VII. Enzymes & other chemotherapeutics

• Enzyme(asparaginase)

• Other chemotherapeutics(procarbazine, hydroxyurea)

Asparaginase(enzyme)

Mechanism of action, kinetics, indications• cleaves asparagine, useful in malignities

where the cells lost possibility of its synthesis

• i.m., i.v. in ALLSide effects

• weak myelosuppression, GIT toxicity & alopecia

• nausea, vomiting, CNS depression, anaphylaxis, hepatotoxicity

VIII. PTK inhibitors (imatinib mesylate)

Mechanism of action, kinetics, indications• PTK inhibition

phosphate group transport from ATP & phosphorylation of tyrozine residues in substrate proteins

• Inhibition of transduction signals transmission • p.o. appl. in therapy of CML & GIST

Side effects• nausea, vomiting, diarrhea• edema, headache & muscle pain• neutropenia &  thrombocytopenia

IX. Monoclonal antibodies (rituximab, trastuzumab)

Rituximab• monoclonal antibody only for i.v. appl. • indicated in lymphoma therapy

Trastuzumab• monoclonal antibody only for i.v. appl. • indicated in  HER2 Neu positive breast ca therapy

Side effects• pseudoinfluenza sy.• fever • headache, chest, abdominal, muscle & joint pain• nausea, vomiting, diarrhea & exanthema

Angiogenesis in cancer

Vasculogenesis vs Angiogenesis

Formation of blood vessels from differentiating angioblasts and their organization into a primordial vascular network, consisting of the major blood vessels of the embryo

Formation of vascular sprouts from pre-existing vessels

Vasculogenesis

Agiogenesis

Physiological versus pathological angiogenesis

Physiological angiogenesis

Pathological angiogenesis

Therapeutic goal

Inhibition of angiogenesis Stimulation of angiogenesis

Embryogenesis Female reproductive systemDevelopment of folliclesCorpus luteum formationEmbryo implantation Successful wound healing

Hemangiomas Psoriasis Kaposi's sarcoma Ocular neovascularization Rheumatoid arthritis Endometriosis Atherosclerosis

Tumor growth and metastasis

Myocardial ischemia Peripheral ischemia Cerebral ischemia Wound healing  Reconstructive surgery Ulcer healing

Initiation

Promotion

Dormant in situ Cancer

1 kg

1 g

1 mg

1 g

1 ng

Established tumor

Dormant cancer cells regain tumorigenic

potential Suzuki M et al AJP 169: 673-681

Angiogenic switch

Progression of Cancer

Hypoxia crosstalk

Accessory cells

Metasta

sis

Hanahan D & Folkman J. Cell. 86:353, 1996

The balance hypothesis for the angiogenic switch

VEGF family

FGF family

PDGF

TGF family

Angiogenin

Angiopoietin-1/Tie2

TNF-HGF/scatter factor

IGF family

IL-8

Nitric oxide

Prostaglandins

Tissue factor

MMPs

.

.

.

Angiostatin/other plasminogen kringles

Antithrombin (cleaved)

Endostatin

Fibronectin fragments

PEX

16-kDa Prolactin

Prothrombin kringle-2

Maspin

Restin

Vasostatin

IL-1, -4, -10, -12, -18

IFNs

TIMPs

1,25-(OH)2-vitamin D

2-Methoxyestradiol

Angiopoietin-2

EMAP-II

gro-IP-10

.

.

.

McDonald & Choyke Nat Med 2003

Normal Blood Vessels vsTumor Blood Vessels

Bevacizumab

• Recombinant, humanized monoclonal antibody that binds to VEGF-A

• Approved for first-line treatment of Non-Small Cell Lung Cancer in combination with Carboplatin and Paclitaxel

• Adding bevacizumab to chemotherapy results in increased median Progression Free Survival by 33%

Concerns

• Since bevacizumab is expected to inhibit new angiogenic growth, concerns have been raised regarding postoperative wound-healing and bleeding complications in patients who undergo surgery within 1 to 2 months of Bevacizumab therapy

Side efects

• Gastrointestinal (GI) perforation

• Wound healing complication

• Hemorrhage

• Neutropenia

Immunosuppressant drugs

- inhibit interleukin-2 production or action cyclosporin, tacrolimus, sirolimus

- inhibit cytokine gene expression corticosteroids

- inhibit purine and pyrimidine synthesis azathioprine

- block the T cell surface molecules involved in signalling polyclonal and monoclonal antibodies

- act by cytotoxic mechanisms cyclophosphamide, chlorambucil

Usage in therapy:

- autoimmune disease (some forms of haemolytic anaemia, glomerulonephritis…)- prevention /or therapy of transplant rejection (kidneys, bone marrow, heart, liver, etc.)

Hazard: - decreased response to infections- facilitation of emergence of malignant cells

Cyclosporin-a fungal polypeptide with potent immunosuppresive activity

Pharmacokinetics- i.v., oral absorption - hepatic metabolism-metabolites excreted in the bile-accumulation in most tissues at conc. 3 to 4 times that seen in the plasma

Unwanted reactions:

- nephrotoxicity- hepatotoxicity- hypertension

Tacrolimus- a macrolide antibiotic- i.v., orally- metabolized by the liver

Unwanted reactions:- neurotoxicity- GIT upsets, metabolic disturbances (hyperglycaemia) reversible by reducing the dosage

Glucocorticoids

- restrain the clonal proliferation of Th cells through decreasing transcription of the gene for IL-2

- decrease the transcription of many other cytokine genes in both the induction and effector phases of the immune response

Azathioprine

is activated to 6-mercaptopurine (a pure analogue –antimetabolite - that inhibits DNA synthesis)

by a cytotoxic action on dividing cells inhibits clonal proliferation in the induction phase of the immune response

Unwanted reactions: - depression of the bone marrow, - nausea and vomiting

Mycophenolate mofetilA semisynthetic derivative of a fungal antibiotic

bioactivated to mycophenolic acid

Action (fairly selective): - restrains proliferation of both T and B lymphocytes- reduces the production of cytotoxic T cells Kinetics:Well absorbed from the GIT Enterohepatic circulation-inactive glucuronides