Pharmacy 754, Spring 2007 Cancer Chemotherapy Kerry McPhail Room 150A Oak Creek Building
[email protected], 737-5808 Reading Materials: Cancer Chapter in Wilson and Gisvold, Ch. 12, pp 343-397 Goodman and Gilman: pp1381-1445 Devlin: pp490-521 on purine and pyrimidine biochemistry http://www.cancerlinks.com/genetics.html/ - links to sites dealing with the genetics of cancer http://www.drugs.com/a-to-z-drug-list.html - comprehensive information on individual drugs http://www.fda.gov/cder/cancer/approved.htm - FDA list of approved drugs http://www.fdanews.com/dailies/dpa/ - latest news on drugs in clinical trial http://www.phrma.org/ - 100 pharmaceutical companies: 2006 survey of medicines in development http://www.rxlist.com/ - index of drugs with chemical description http://www.cancer.gov/ - National Cancer Institute home page, statistics, info on research, clinical trials etc http://www.cancer.org/docroot/home/index.asp/ - American Cancer Society 1 http://5aday.nci.nih.gov/ - cancer and nutrition http://www.cancerindex.org/ - guide to cancer-related websites
OBJECTIVES • To understand the rationale for cancer chemotherapy • To know the general classes of cancer drugs. • To know the representative drugs given for each class: i. molecular structure ii. important functional group for activity, iii. mechanism of action in words or as specified in lecture notes, iv. major use and major toxicities v. cautions in administration or drug interactions
• To know common drug regimens for major cancers and to understand the general approach to avoid drug resistance 2
Goals of Cancer Treatment 1. To cure the patient of cancer 2. To prolong survival with good life quality 3. To relieve symptoms (e.g. - pain) = palliative therapy
Responses 1. Complete Remission - Complete disappearance 2. Partial Remission - 50% decrease in measurable tumor mass. 3. Stable Disease - does not meet criteria for either partial remission or disease progression. 4. Disease Progression - increase in tumor mass by 25% or more. 3
Cancer Treatment Strategy Combined modalities and adjuvant therapy 1. Radiation Therapy 2. Surgery 3. Chemotherapy 4. Immunotherapy 5. Patient History • renal/hepatic function, nutrition, previous cancer • therapy, and mental outlook 6. New Cancer Registry for Oregon (OSCaR) in 1996: • support of cancer control activities • early detection and prevention of cancer • coordinated through the Oregon Health Division (Portland) 4
When is Chemotherapy Used? After an operation – (adjuvant therapy) when all visible cancer has been removed but there is a risk that cancer cells may have been left behind. Before an operation – (neo-adjuvant therapy) to shrink the tumor and make it easier to remove where the cancer is too large or too strongly attached to surrounding healthy tissue to be removed by an operation. Chemotherapy can also be used in this way before radiation therapy Advanced cancer – where the disease has spread, chemotherapy is given to shrink and control the cancer, to prolong life and improve its quality; Chemotherapy alone is rarely given with the hope of getting rid of all the cancer and achieving a cure. 5
Adjuvant Therapy
“You are suggesting that I have treatment which will make me temporarily unwell, to treat cancer that you can't find, and can't be sure you have eliminated even when treatment is finished." 6
How are the chemotherapeutic drugs given? by injection into a vein - most commonly (IV) by mouth (PO) by injection into a muscle (IM) by injection under the skin (subcutaneous) by injection into the fluid around the spine (intrathecal, IT) by subcutaneous implant (SC)
http://www.rxlist.com/ http://www.accessdata.tda.gov/scripts/cder/onctools/druglit.ctm 7 http://www.fda.gov/cder/cancer/druglistframe.htm
Checkpoint Activation
Chemotherapy Ionizing Radiation Tumor Cell
Repair
Minor Pathway
Apoptosis
Stress
Tumor Cell Stress
Major Pathway
Cell Death by Mitotic Catastrophe
Unwanted Pathway Resistant Tumor Cell
More Permanent Genetic Alterations 8
Toxicity to patient
Chemotherapy Ionizing Radiation Normal Cell
Repair
Cell Cycle arrest
Apoptosis
Stress
Normal Cell Stress
Cell
Permanent Genetic Alterations
Chemotherapy and radiation therapy are not as toxic to normal cells as to tumor cells because: (1) Normal cells don’t normally replicate as fast as tumor cells; (2) Normal cells have intact checkpoint pathways to repair 9 damaged DNA.
Concentration of Chemotherapeutic Agent
Tumor Cells
Normal Cells
Achievable Therapeutic Doses Ideal Therapeutic Window
Cytotoxic DNA Mutations
Cytotoxic DNA Mutations (lead to resistant tumors)
(may lead to secondary malignancies)
No Effect
No Effect 10
Chemo
Chemo
Chemo Chemo
First Round
Second Round
Tumor
Chemo Chemo Chemo
Third Round
Chemo
Cure Cancer: Kill all the cells
Cancer regrowth: some Tumor cells survived and are now resistant to treatment
Chemo
Chemo Chemo Chemo
11
Purine Biosynthesis
Pyrimidine Biosynthesis
Antimetabolites Topoisomerase Inhibitors
Ribonucleotides
Deoxyribonucleotides
DNA Intercalators
Alkylating Agents Epigenetic Drugs DNA
Hormones
Ionizing Radiaton
Immunotherapy agents
Antisense
RNA
Microtubule Inhibitors
Signal Transduction TK Inhibitors12
Proteins Microtubules
Enzymes
Cyclin A/cdc2
Cyclin D/cdk4,6
Cyclin B1/cdc2 Mitosis (M)
p21
p21
G1 G2
p21
Cyclin A/cdk2
DNA Synthesis (S)
p21
Cyclin E/cdk2 13
Classes of Cancer Agents 1. Alkylating Agents
reactive molecules that alkylate DNA and proteins, interrupting their normal function.
2. Antimetabolites
structurally resemble normal intermediates in the biosynthesis of purines/pyrimidines, but inhibit the enzymes involved in transforming that intermediate.
3. Intercalators
“slip” in between stacked bases of DNA and disrupt its normal operation - ie - DNA and RNA synthesis.
4. Antimitotics
inhibit either the polymerization or depolymerization of tubulin, the subunit of microtubules, that are essential for separating chromosomes at mitosis.
5. DNA Cleaving Agents
chemically cut the DNA backbone, either directly or using a component of the cells normal machinery.
6. Hormones
estrogen blockers prevent estrogen binding to receptors and subsequent gene expression/repression; estrogen synthesis inhibitors reduce circulating estrogen levels.
7. Immunotherapy
monoclonal antibodies and biological response modifiers.
8. Signal Transduction Inhibitors
14 protein tyrosine kinase and proteasome inhibitors, antisense drugs.
1. Alkylating Agents Alkylation – replacement of hydrogen on an atom by an alkyl group; substitution reaction in which a nucleophilic atom of DNA or protein displaces a leaving group from the alkylating agent: nu-H + alkyl-Y
alkyl-nu + H+ + Y-
Nucleophilic Sites of the DNA Bases
15
Normal DNA Base Pairing
16
Alkylating Agent
17
Generalized Mechanism of Action of Alkylating Agents HN-R or HS-R of proteins Cl
Cl
N
N
N
N N
Mechlorethamine
N NH
N
N
O
O
O
Cl
Cl
Cl
N
NH2
N
NH N
HN
NH2
NH2
N
DNA
DNA
DNA
NH
OHC
interstrand crosslinking
H2O
depurination (deletion of guanine) Cl
N
O HN H2N
N
N
N
N
N
DNA
DNA
NH N
N
O
O
NH2
HN H2N
N
H+ O
N O
N
N
N
N
DNA
DNA
N
NH
NH N
NH2
N
N
NH2
DNA 18
Consequences of Alkylating Agents • alkylation of DNA, N-7 of guanine • second cyclization of the second side chain to form covalent bond with another nucleophilic moiety: 1. DNA base mispairing and mutation 2. DNA strand crosslinking 3. DNA strand breakage • cell-cycle-phase nonspecific (DNA damage during all cell cycle phases) • activates cellular responses including cell cycle arrest, DNA repair and apoptosis (programmed cell death) • more cytotoxic to rapidly proliferating cells (undergoing DNA synthesis) • cytotoxicity correlates very well with the levels of interstrand crosslinking 19
A. Nitrogen Mustards Discovery of the Nitrogen Mustards - Bifunctional Alkylating Agents • • • • •
Sulfur mustard and ethyleneimine toxicity to animals described in 19th century Sulfur mustard used in World War I caused systemic effects including leukopenia, bone marrow aplasia, ulceration of GI tract and lymphoid tissue suppression Sulfur mustard active against animal tumors but non-specific Nitrogen mustards synthesized between WWI and WWII showed selective toxicity to lymphoid tissue, tested against tumors of the lymphoid system in animals Many analogs produced, but rational design strategies have failed NH O
N Cl
P
O
Cl N
N
HN
Cl
O
Cl
O
Cl
Mechlorethamine
Cl
Cyclophosphamide
N H
Uracil Mustard Cl
HO
Cl
N Cl
O
Cl
N
N O HO
Chlorambucil
Cl
NH2 O
Melphalan
Cl P
N H
20
O
Ifosfamide
Mechlorethamine (Mustargen, nitrogen mustard)
Chlorambucil (Leukeran) HO
N Cl
O
Cl
Cl
N
Administration: IV
Administration: PO
Indications: • combination therapy for Hodgkins lymphoma with vincristine (Oncovin), procarbazine and prednisone = MOPP regimen; largely replaced by more stable alkylating agents • cutaneous T-cell lymphoma (topical)
Indications: palliative treatment of CLL, primary macroglobulinemia, malignant lymphomas including lymphosarcoma, giant follicular lymphoma, Hodgkins lymphoma
Side Effects and Toxicity: powerful vesicant, nausea and vomiting, lacrimation, myelosuppression, infertility/sterility, carcinogenic, mutagenic, teratogenic. Extravasation is countered with isotonic sodium thiosulfate (167 mM) to protect tissues Pharmacology: highly reactive, combines with water or reactive cellular compounds within a few minutes after administration.
Cl
Side Effects and Toxicity: bone marrow suppression, lymphopenia, neutropenia, carcinogenesis leading to secondary malignancies, infertility/sterility, mutagenic, teratogenic Pharmacology: metabolized rapidly to phenylacetic acid mustard (also active); less reactive than Mechlorethamine 21 (N electron delocalization)
Cyclophosphamide (Cytoxan) NH O
P
Ifosfamide (IFEX) Cl
Cl N
N O
O Cl
Cl P
N H
O
Administration: IV, PO
Administration: IV
Indications: lymphomas, multiple myeloma leukemias, neuroblastoma, adenocarcinoma of the ovary, retinoblastoma, carcinoma of the breast.
Indications: in combination, third line treatment of germ cell testicular cancer; Mesna to prevent hemorrhagic cystitis.
Side Effects and Toxicity: not vesicant or irritant, urinary toxicity (hemmorhagic cystitis), carcinogenesis, mutagenesis, impairment of fertility (loss of germ cells), leukopenia, thrombocytopenia, cardiac toxicity, nausea and vomiting, anorexia
Side Effects and Toxicology: Generally more toxic than cyclophosphamide: hemmorhagic cystitis, thrombocytopenia, neurologic manifestations (hallucinations, confusion, and coma), nephrotoxicity, nausea and vomiting, carcinogenic and mutagenic
Pharmacology: biotransformed in the liver to active alkylating metabolites by microsomal p450 enzymes (CYP2B and CYP3A4, resp); produce interstrand DNA crosslinking. 22
Cyclophosphamide Metabolic Activation O
H N O
CH 2 CH 2Cl P O
HOOC
N CH 2 CH 2Cl
NH2 CH 2 CH 2Cl O P O
N CH 2 CH 2Cl
Inactive metabolites aldehyde oxidase
Hepatic CYPs
carbinolamine
amino aldehyde non-enzymatic
Toxic metabolites
23
Sterile necrotizing hemorrhagic cystitis • acrolein production is probable cause • associated with chronic administration of cyclophosphamide/ifosfamide • cause for stopping treatment Minimize effects by: • high water intake and take in the morning • bladder irrigation with thiol compounds • systemic treatment with N-acetylcysteine and Mesna: Cytoprotective Agent:
Mesna (Mesnex)
O
HS Na
-O +
S
O
2-mercaptoethanesulfonate
• used prophylactically and therapeutically for Px & Rx of Cystitis • injectable as inert disulfide which is reduced in renal tubules to Mesna • binds to and detoxifies urotoxic metabolites of cyclophosphamide/Ifosfamide
24
B. Nitrosoureas
Cl
H N
O
O
N
N
N
Cl
O
H N
N O
Carmustine
O OH HO HO
O
N
OH
O
Streptozocin O
N
H N
N
Cl
Lomustine
O
N
H N
OH
Cl
O
Semustine
HO HO
O
N
H N OH
N
Cl
O
Chlorozocin
• unstable in aqueous solution under physiological conditions; undergo spontaneous breakdown to become effective alkylating and carbamoylating agents: • bifunctional alkylating agents - toxicity is associated with the formation of interstrand DNA crosslinks 25
• also form protein adducts by addition of carbamoyl groups to lysine residues
Mechanism of Action of the Nitrosoureas H+ O
Bifunctional alkylating agent (DNA and RNA)
N H N
N
Cl
Carbamoylating Agent
O
Lomustine (CCNU) HO N Cl
Cl
O C N
N
+
CH2+
N2
hydrolysis
+
HO-
Lysine -NH2
guanine (also cytidine, adenine) Cl
Protein
N N DNA
H N O
OH N
H N
N NH2
crosslinking possible
Protein Adducts - can alter function of DNA polymerase and DNA repair enzymes
26
Lomustine (CeeNu, CCNU) Administration: PO Indications: single agent and in combination for brain tumors (primary and metastatic) and Hodgkins lymphoma (secondary therapy)
O N
H N
N O
Cl
Side Effects and Toxicity: • delayed myelosuppression: blood counts should be monitored 6 wks following treatment. • pulmonary toxicity • secondary malignancies can occur with long term usage. • liver and renal function can be affected. Pharmacology: Interstrand and intrastrand DNA cross-linking 27
Streptozocin (Zanosar)
Chlorozotocin (Chlorozocin) O
O OH HO HO
O
N
H N OH
N O
OH HO HO
O
N
H N OH
N
Cl
O
natural product – Streptomyces achromogenes diabetogenic
non-diabetogenic
Administration: IV Indications: treatment of metastatic islet cell carcinoma of the pancreas. Pharmacology: Inhibits DNA synthesis and cell proliferation; high affinity for B cells of the islets of Langerhans and causes cytotoxicity (lowers beta cell nicotinamide adenine dinucleotide (NAD)), leading to diabetes in experimental animals. Side Effects and Toxicology: renal toxicity (dose dependent, cummulative – can be fatal), additive toxicity when administered with doxorubicin, confusion, lethargy, and depression, bone marrow suppression, hepatic toxicity, carcinogenic, mutagenic, and impairs fertility, severe nausea and vomiting 28
C. Platinum Coordinated Compounds NH3 H3N
Pt
H3N
Cl
H2 N
O O Pt
H3N
Cl Cisplatin
Pt
HO NH Cl 2 Iproplatin
O
O
O
Pt
O
N H2
O
Oxaliplatin
Carboplatin
HO NH2 Cl
O
H2 N Cl
Cl
Pt
N Cl H2
Cl
not FDA approved
Ormiplatin Tetraplatin
Cisplatin – described by M. Peyrone in 1845; – structure elucidated by Werner in 1893; – rediscovered in 1965 by Rosenberg –inhibitory effect of platinum electrodes on mitosis in E. coli but bacteria grow to 300X normal length! – over 1000, platinum derivatives have been made and tested 29 –generally cis isomers
http://science.kennesaw.edu/~mhermes/cisplat/cisplat12.htm
30
Cisplatin forms DNA adducts as well as intrastrand and interstrand cross-links that lead to DNA strand breaks and miscoding errors.
31
Cisplatin (platinum shown in red) forms a complex with DNA, causing it to bend.
Cisplatin (Platinol-AQ)
Carboplatin (Paraplatin)
"penicillin of cancer drugs"
H2N
NH2 H2N
Pt
O
Cl
Cl
O Pt
H2N
O O
Administration: IV
Administration: IV
Indications: metastatic testicular and ovarian cancer, head and neck carcinomas, lung cancer advanced bladder cancer
Indications: advanced ovarian cancer
Side Effects and Toxicity: cumulative renal toxicity, myelosuppression, nausea and vomiting, ototoxicity (loss of hearing) FDA approved 1978
Side Effects and Toxicity: myelosuppression resulting in infection or bleeding, nausea and vomiting, anaphylactic reactions. FDA approved 1989 leader in sales much less toxic than cisplatin
32
Oxaliplatin (Eloxatin) H2 N
O
O
O
O
Pt
N H2
Compared to cisplatin: • NH2 replaced by cyclohexyldiamine for improved antitumour activity • Cl- ligands replaced by the oxalato bidentate to improve water solubility. FDA approved January 2004 Administration: IV Indications: in combination (FOLFOX) with infusional 5-FU and Leucovorin LV for advanced colorectal cancer Side Effects and Toxicity: neuropathy, specifically including sensitivity to cold and numbness in the hands and feet, fatigue nausea, vomiting, and/or diarrhea, neutropenia, hearing loss
33
Amifostine (Ethylol)
Cytoprotective Agent:
H2N
N H
O S P OH OH
Administration: IV Indications: • reduction of cumulative toxicity associated with repeated doses of cisplatin • reduces incidence of xerostomia caused by postoperative radiation treatment affecting parotid glands Pharmacology: • free thiol detoxifies reactive cisplatin metabolites in kidney • higher pH, better vascularity and higher alkaline phosphatase in normal cells – selective dephosphorylation Side Effects and Toxicity: hypotension, severe nausea, vomiting (requires anti-emetic administration)
34
2. Antimetabolites • prevent biosynthesis or use of normal cellular metabolites • structural analogs of metabolite that is antagonized, a cofactor, or end product • interfere with the production of nucleic acids • mechanisms of action: competition for binding sites on enzymes and incorporation into nucleic acids • inhibit growth of the most rapidly proliferating cells in the body. Three categories of antimetabolites:
A. Folic Acid Derivatives:
Methotrexate Leucovorin Pemetrexed disodium
B. Purine Analogs:
6-Mercaptopurine Thioguanine Pentostatin Fludarabine Phosphate Cladarabine
C. Pyrimidine Analogs:
5-Fluorouracil Fluorodeoxyuridine Cytarabine Gemcitabine
35
A. Folic Acid Derivatives H N
H 2N
N
FOLIC ACID (vitamin B9, vitamin M, pteroyl-L-glutamic acid, folacin)
N
N O
HN
O
H N O
N
H 2N N
O
OH OH
N N
N
O
H N
NH2
N
OH
H N
O
H N
N O
O
Leucovorin
O
H N
O
OH
Methotrexate
O
O
OH OH
(folinic acid)
(amethopterin) O O
H2N
N
O
O- Na+ .7H O 2
N H
HN
Farber 1948
H N
H 2N
N H
O- Na+ O
Pemetrexed disodium
36
Interconversion of Folic Acid Derivatives
O R = CNHCH(CH2)2CO2H
H
CO2H
R
R
37
Biosynthesis of Thymidine O
O HN
HN
CH 3
N OH O O P O O HO
N OH O O P O O HO
Thymidylate Synthase HO
HO
Thymidine Monophosphate
Uridine Monophosphate N5, N10 - Methylene Tetrahydrofolate
Dihydrofolate (DHFA)
NADPH + H+ Dihydrofolate Reductase
Tetrahydrofolate H N
H 2N N
H N
NADPH H N
N O
O
H N
O O
O
OH OH
Leucovorin
Methotrexate 38
Methotrexate (Folex, Mexate) N N
O
H N
HO HO
O
N
N
NH2 N
NH2
amino group alkylation, partial reduction, and removal or relocation of heterocyclic N decreases activity
O
Administration: IV, PO, IM, IT Indications: meningeal leukemia, non-Hodgkin’s lymphoma, osteosarcoma, choriocarcinoma, lung carcinomas (small cell and squamous; using rescue therapy with leucovorin) Pharmacology: inhibits dihydrofolate reductase (pseudoirreversible) - blocks the synthesis of thymidylate and purines; affects S phase of cell cycle – most effective in logarithmic growth phase Side Effects and Toxicity: teratogenic, abnormal liver function, leukopenia, thrombocytopenia, fatal myelosuppression and gastrointestinal toxicity in combination with NSAIDs, lung disease, diarrhea and ulcerative stomatitis, spinal chord irritation (when given IT)
39
Leucovorin (Citrovorum factor) H N
H 2N N
H N H N
N O
O
H N
O O
O
N-formyl tetrahydrofolic acid OH
OH
Administration: PO Indications: rescue therapy: antidote for folic acid antagonists, such as methotrexate; Pharmacology: • does not require reduction by the enzyme dihydrofolate reductase for biosynthesis of pyrimidines: overcomes blockade of tetrahydrofolic acid production in normal cells; • also inhibits active transport of methotrexate into cells and stimulates its efflux; • enhances toxicity of fluoropyrimidines (ie 5-FU) by stabilizing binding of 5-FU to thymidylate synthase Side Effects and Toxicity: allergic sensitization; enhances cytotoxic effects of 5-FU
40
Pemetrexed disodium (Alimta) O O HN H2N
N
N H Administration: IV
O
O- Na+ .7H O 2
N H
O- Na+ O
synthetic, rational drug design
Indications: inoperable malignant pleural mesothelioma in combination with cisplatin; single agent for locally advanced or metastatic NSCLC after prior chemotherapy. Accel. Approv. (clinical benefit not established) 2004 Pharmacology: inhibits thymidylate synthase, dihydrofolate reductase, and glycinamide ribonucleotide formyltransferase - key enzymes required for the de novo bio-synthesis of thymidine and purine nucleotides Side Effects and Toxicity: nausea and vomiting, diarrhea, myelosuppression, anemia, infection, fatigue, rash, loss of appetite 41
B. Pyrimidine Analogs O
O
O
HN O O HO P O OH
N O
HN
F
HN O
O
N H
N
N
O
O
HO
Thymidine Monophosphate
5-Fluorouracil
O
N O
N O
HO
HN
N
OH
Cytidine Monophosphate
F
N
O
O
F
Gemcitibine
N O
F
HO
OH
Cytarabine
NH2
N O
HO
Fluorodeoxyuridine
NH2
N O
HO
HO
HO
O HO P O OH
NH2
F
HO
OH
Capecitabine 42
Metabolic Activation of 5-FU
uridine kinase
phosphoribosyltransferase present in some tumors
43
5-FU substrate causes terminal product involving covalently bound enzyme, cofactor and substrate
44
5-Fluorouracil (Adrucil, Efudex, Fluoroplex)
O F
HN O
N H
rational drug design 1957 – Heidelberger observed that certain tumors used uracil more than orotic acid (nucleic acid pyrimidine precursor in normal tissue)
Administration: IV Indications: • breast, colorectal, bladder, gastric, pancreatic, head and neck, and anal carcinoma; • co-administration of leucovorin increases 5-FU cytotoxicity; • adjuvant chemotherapy for colorectal carcinoma in conjunction with levamisole Pharmacology: • inhibition of thymidylate synthethase; incorporation of FUTP into RNA and DNA; • rate of catabolism determined by dihydropyrimidine dehydrogenase which can be inhibited by 5-ethynyluracil to raise 5-FU therapeutic index 2-4 fold. Side Effects and Toxicity: dose limiting myelosuppression - granulocytopenia and thrombocytopenia; GI toxicity; stomatitis; alopecia and partial loss of nails; hyperpigmentation and vein toxicity; hand45 foot skin irritation, neurotoxicity, cardiotoxicity.
Capecitabine (Xeloda) O HN F
N O
prodrug of fluorodeoxyuridine
N O
HO
OH
Administration: PO Indications: in combination with docetaxel for metastatic breast cancer resistant to paclitaxel and anthracyclines; adjuvant treatment in patients with Dukes’ C colon cancer (June 2005) Side Effects and Toxicity: bone marrow depression, diarrhea, mutagenesis in mice, reversible infertility, teratogenicity, hyperbilirubinemia, drug interactions with antacids and leucovorin 46
Gemcitabine (Gemzar) NH2 Gemcitibine
N O HO
N
B
O
O
OPP
F
HO
B
ribonucleotide reductase
O
OPP OH
HO
F Administration: IV Indications: first-line treatment for locally advanced or metastatic pancreatic cancer; combination with cisplatin for inoperable advanced NSCLC; ovarian cancer Pharmacology: cell cycle S-phase specific - gemcitabine diphosphate inhibits ribonucleotide reductase (dNTP’s for DNA synthesis) and competes with dCTP for incorporation into DNA; only one additional nucleotide is added to the growing DNA strands after incorporation; no DNA repair possible Side Effects and Toxicity: myelosuppression - leukopenia, thrombocytopenia, and anemia; GI toxicity, stomatitis, hepatic 47 dysfunction, fever, dermatitis.
C. Purine Analogs O
S HN
N
HN O HO
P
H 2N
N
N
N
SH
H N
N
N
H 2N
O
O
OH
N
Thioguanine
6 Mercaptopurine HO
N
H N
OH
Guanosine Monophosphate NH2
NH2
NH2 N
HO
P
N
Cl
N
N O
HO
O
O
N
N N
O
N
N
N
F OH
OH
N
N
HN
N N
O P O OH
N
HO O
O
OH HO
OH
Adenosine monophosphate
HO
OH
OH
HO
Cladribine
Fludarabine Phosphate
Pentostatin 48
6-Mercaptopurine (Purinethol) S
S HN
N
HN
H N
activation
N O
O
HO P O OH
N
HO
OH
Administration: PO initial, rate-determining step in purine biosynthesis
Indications: leukemias (AML, ALL, CML not CLL); combination chemotherapy with vincristine, prednisone, and L-asparaginase Pharmacology: inhibits de novo synthesis of ribonucleotides; some is converted to 6-thioguanine and incorporated into DNA (NB dosage in combination). Side Effects and Toxicity: anemia, leukopenia, thrombocytopenia, hepatotoxicity, immunosuppression, renal toxicity, 49 carcinogenic, nausea, vomiting, oral thrush, diarrhea, skin rash, and headache, teratogenic
OH HN
N N
Pentostatin (Nipent, 2-deoxycoformacin, DCF) natural product from Streptomyces antibioticus
N
HO O
OH
Administration: IV Indications: used as a single agent in the treatment of alpha-interferon-refractory hairy cell leukemia; also CLL, CML, PML, cutaneous T-cell lymphoma, non-Hodgkins lymphoma. Pharmacology: inhibitor of adenosine transaminase -leads to unproportionally elevated levels of dATP and ATP, causes an inhibition of ribonucleotide reductase, blocks DNA synthesis. Side Effects and Toxicity: myelosuppression, renal toxicity at high doses, and rashes; if co-administered with fludarabine phosphate, extremely toxic to pulmonary system. 50
3. DNA Intercalators (Antitumor Antibiotics)
Adriamycin (doxorubicin) Daunomycin (daunorubicin) Idamycin Mitoxantrone Dactinomycin Plicamycin Epirubicin – changes in sugar Valrubicin – changes in sugar Bleomycin
• Mediate DNA strand breaks through radical formation (cell phase independent) • Inhibition of Topo II - DNA cleavage complex (S-phase specific)
Mediates DNA strand breakage through radical formation
51
DNA Intercalators
O
• planar, multiple ring molecules interact with bases of DNA and insert between them; • insertion causes a “stretching” of the DNA duplex • DNA polymerase inserts an extra base opposite an intercalated molecule: frameshift mutations Many intercalating agents induce DNA strand breakage by: • inhibition of topoisomerase II - DNA cleavage complexes 52 • generation of reactive radical species
Doxorubicin
53
Daunorubicin (Cerubidine, Daunomycin)
Doxorubicin (Adriamycin) O
O
O
OH
O
OH
OH
OH
OH O
O
OH
O
O
O
O
OH
O
O OH
OH NH2
NH2
Anthracyclines from Streptomyces peucetius var. caesius and Streptomyces coeruleorubidus Administration: IV Indications: soft and solid tumor types including: ALL, AML, Wilm’s tumor, neuroblastoma, soft tissue and bone sarcomas, breast carcinoma, ovarian carcinoma, thyroid carcinoma, gastric carcinoma, Hodgkin’s disease malignant lymphoma, lung carcinoma Pharmacology: DNA strand breakage by: • DNA intercalation - inhibition of DNA processing and transcription; • Inhibition of Topoisomerase II - double strand DNA breaks; • semiquinone species - free radical or OH radical formation leading to DNA and cellular damage Side Effects and Toxicity: myocardial toxicity leading to congestive heart failure, severe local tissue necrosis if extravasation 54 occurs, severe myelosuppression, hepatotoxicity.
Crystal structure of daunomycin-DNA complex: daunomycin intercalates into GC base pairs while the amino sugar ring, daunosamine, fits in the minor groove.
Qu, Xiaogang et al. (2001) Proc. Natl. Acad. Sci. USA 98, 14212-14217 Copyright ©2001 by the National Academy of Sciences
55
Cardiotoxicity of Doxorubicin/Daunorubicin
56
57
Xu X, Perrson HL, Richardson DR. Mol. Pharmacol. 2005 68: 261-271
Dexrazoxane (Zinecard)
Cytoprotective Agent:
O
O O
NH O
N
O
N
in vivo
HO H2N
HN
NH2 OH O
O
O Administration: IV (before doxorubicin is administered)
Indications: reduction of cumulative cardiotoxicity of doxorubicin Pharmacology: potent intracellular chelating agent complexes with iron, interrupts free radical generation associated with doxorubicin-iron complexes Side Effects and Toxicity: enhances myelosuppression caused by doxorubicin
58
Mitoxantrone (Novantrone) O
HN
OH O
HN
H N
N H
OH
OH
Administration: IV Indications: • primary treatment of leukemias (acute non-lymphocytic leukemias in adults: includes myelogenous, promyelocytic, monocytic, and erythroid acute leukemias); • in combination with corticosteroids for the treatment of advanced hormonerefractory prostate cancer. Pharmacology: partial anthracycline structure; DNA intercalator; DNA topoisomerase II inhibitor induces DNA double strand breaks; not cell cycle phase specific. Side Effects and Toxicity: severe bone marrow suppression (especially neutropenia), cardiotoxicity (reduced compared to anthracycline antibiotics – does not form oxygen-free radicals in a 59 redox cycling process)
O
NH2 H N N
N H 2N
HO
Bleomycin (Blenoxane – bleomycin sulfate) NH2 NH2 O
O HO O H HN N H H N O H OH N O O H OH
S+
O
H H N O HO
OH OH
H
O
O N
NH S N
N H
S
mixture of cytotoxic glycopeptide antibiotics isolated from a strain of Streptomyces verticillus
OH O O
NH2
Administration: IV Indications: palliative agent for squamous cell carcinoma of the head and neck, lymphomas, and testicular carcinoma. Pharmacology: multiple biochemical properties: most cytotoxic is DNA fragmentation; binds to DNA through its amino terminal peptide, and the activated complex generates free radicals that are responsible for the scission of DNA Side Effects and Toxicity: 60 pulmonary toxicity (pneumonitis leading to fibrosis), mutagenic and carcinogenic, skin irritation.
Bleomycin (BLM) Structure Activity Relationships Metal Binding Domain NH2 H N
O
NH2 NH2
H 2N HN
HO
OH O OH
O
H H N
O HO O H N H H N
O HO
H N H
O O
OH OH
OH O O
S+
Linker
O
N
N
Bithiazole Domain
NH2
Carbohydrate Domain
H
O
O N
NH S N
N H
S
1. Metal Binding Domain - binds to a redox-active metal (Fe2+ or Cu+) and oxygen to mediate DNA and RNA degradation; abstraction of H+ atoms from DNA and determines sequence specific DNA cleavage site 2. Bithiazole Domain is involved in DNA binding 3. Linker can be increased in length and biological activity is retained 4. Carbohydrate Domain - may function in cell recognition and uptake. 61
62
4. Antimitotics Inhibit either the polymerization or depolymerization of tubulin, the subunit of microtubules, that are essential for separating chromosomes at mitosis
Inhibit depolymerization Paclitaxel Docetaxel Epothilone
Inhibit polymerization Vincristine Vinblastine Vinorelbine Vindesine Maytansine Rhizoxin
63
64
65
66
Microtubule Spindle (green)
Chromosomes (blue)
67
Pacific Yew Tree • Late 1950’s - NCI program for screening plant extracts for chemotherapeutic potential. • Extracts from the bark of the Pacific Yew (Taxus brevifolia) inhibited tumor growth.
• • • •
1969 – Taxol isolated as active component 1971 – molecular structure solved 1983 – Taxol clinical trials started by NCI 1992 – FDA approval for treatment of resistant ovarian cancers. • 1994 – FDA approval for treatment of recurrent breast cancer • 100 mg Taxol per kilogram of bark (0.01%) • NCI clinical trials required 27,000 kg of bark. • 9,000 trees required for trials • 100 yr old Yew tree = 3 kg of bark • 1990 – petition failed to declare Pacific Yew a threatened species under the Endangered Species Act. 1992 – sources of taxol very scarce
68
Paclitaxel (Taxol) O O O
O O
O
NH O
H O
OH
OH
O O
O O
O
world’s leading antineoplastic agent in terms of sales
Administration: IV
10-deacetylbaccatin III natural product from needles and branches of the European Yew (Taxus baccata).
Indications: advanced ovarian carcinoma, relapsed breast cancer, melanoma, non-small cell lung cancer Pharmacology: binds to tubulin: promotes the stable assembly of microtubules that prevents growing cells from completing mitosis. Side Effects and Toxicity: myelosuppression, severe hypersensitivity, cardiovascular toxicity, peripheral neuropathy, 69 impairment of fertility, nausea and vomiting, alopecia, hepatotoxicity
Taxol binds to the beta tubulin subunit of microtubules and inhibits the depolymerization of microtubules
Taxol 70
Taxol Structure Activity Relationships O O
O O
NH O
11
2
14
O
H 1
3
OH
O
O
OH
2
O O
O O
Side Chain 1. The C-2 OH group is needed for full activity 2. The C-3 phenyl ring is also required for full activity (19-fold activity reduction when removed)
O
Skeleton 1. Removal of C-2 benzoyl group results in large decrease in activity 2. The oxetane ring is crucial for maintaining activity
71
The Vinca Alkaloids
Catharanthus roseus (Vinca roseus)
72
A
B OH N
N H
N H H 3COOC H3CO
H
N
N R 1 HO R 2
N H H 3COOC
R3
Structure A VINBLASTINE
VINDESINE
R2
R 1 HO R 2 R3
O C OCH3
O O C CH3
C H
O C OCH3
O O C CH3
CH3
O C NH2
OH
CH3
O C OCH3
O O C CH3
CH3 O
VINCRISTINE
N
H3 CO R1
N
R3
x
Structure B VINORELBINE
73
Vinca Alkaloids Structure Activity Relationships OH N H N H H 3COOC Vinblastine
H3 CO
N 4
N H 3C HO
OOCCH 3 COOCH 3
1. Reduction or replacement of the hydroxyl groups results in decreased activity 2. Hydrogenation of either double bond reduces activity 3. Loss of the C4 - acetyl group destroys it’s anti-leukemic effect. All of these modifications, alter the binding affinity of vinblastine for the beta subunits of microtubules.
74
Vincristine Sulfate (Oncovin)
Vinblastine Sulfate (Velban)
Administration: IV
Administration: IV
Indications: acute pediatric leukemias, useful in combination therapy (MOPP) for Hodgkins disease and non-Hodgkins lymphoma, rhabdomyosarcoma, neuroblastoma, and Wilm’s tumor.
Indications: In combination (bleomycin and cisplatin) for metastatic testicular cancers; in combination curative treatment of Hodgkins disease; Kaposi’s sarcoma; less frequently for choriocarcinoma and carcinoma of the breast
Side Effects and Toxicity: neuromuscular dysfunction, acute uric acid nephropathy, acute shortness of breath and severe bronchospasms (most common when administered with mitomycin c), nausea and vomiting.
Side Effects and Toxicity: myelosuppression (leukopenia), neurological toxicity; severe bronchospasms (especially when given with mitomycin c), nausea and vomiting
Pharmacology: inhibition of mitotic spindle formation, resulting in the arrest of dividing cells at metaphase (cell cycle phase specific); bind to “vinca site” in the “vinca binding domain” of -tubulin subunit polymerization with -tubulin subunits; hepatic metabolism 75
Vinorelbine Tartrate (Navelbine) semi-synthetic
Vindesine (Eldisine, Fildesin) semi-synthetic not commercially available in USA
Administration: IV
Administration: IV
Indications: single agent or in combination for firstline treatment of unresectable NSCLC, commonly used in combination with cisplatin
Indications: melanoma, lung carcinoma and uterine cancer.
Side Effects and Toxicity: Myelosuppression (granulocytopenia), teratogenic, severe bronchospasms (especially when co-administered with mitomycin c), mild peripheral neuropathy, mild to moderate nausea
Side Effects and Toxicity: bone marrow suppression, mild peripheral neuropathy, nausea and vomiting
Note: Vinca alkaloids antitumor effects are blocked by multidrug resistance. MDR tumor cells display cross-resistance to vinca alkaloids, anthracyclines, taxanes and epipodophyllotoxins, and contain increased P-glycoprotein levels and/or mutations in76 tubulin.
5. DNA Cleaving Agents (Topoisomerase Inhibitors) Topoisomerase II Inhibitors
Topoisomerase I Inhibitors O
O
O
O
N
O
N
H
O OH
H
HO
Camptothecin
O O
O
N
O OH
O
Etoposide
O N
O
HO
O N
O
O
HO
S O
HO
O
Topotecan O N
O
H
O O
N
O N
O
H H O OH H O H OH
O
O
HO
HO
O O
O
77
N
Irinotecan
Teniposide
DNA Replication
Topo I Camptothecin
78
DNA Topoisomerase I Topo I binds covalently to doublestranded DNA through reversible trans-esterification (Enz-Tyr binds to 3’-phosphate end of DNA strand: single strand break)
Cellular processing of topo-I cleavable complexes. The collision models. (A) A replication fork collision model. (B) An RNA polymerase collision 79 model. CPT = camptothecin (S-phase specific).
A Model for Camptothecin Interaction with Topo I -DNA Cleavage Complexes
80
81
Camptothecin • Isolated from bark of Chinese tree Camptotheca acuminata (1966) • not FDA approved – severe unpredictable toxic effects (myelosuppression and hemorrhagic cystitis); limited water solubility.
O 7
9 8
10
A 11
B 13
12
5 6
N 1
C 2
4
N
23 17 16
D
3
O E
15 14 19
20
22
21
O OH
18
Alterations at C-7, C-9, C-10, and C-11 are well tolerated
1. The pyridone moiety of the D ring is essential 2. The lactone moiety of the E ring is essential 3. The hydroxyl group at C-20 is essential, and needs to be the S-stereoisomer 4. The planar structure of the molecule is required (ie distortion of the C-D-E rings results in activity loss) 5. Additions to C-12 result in inactivation
Camptothecin does not bind to DNA in the absence of Topoisomerase I and can only bind reversibly to the cleavage-complex intermediate 82 formed between Topoisomerase I and DNA
Topotecan (Hycamtin)
Irinotecan (Camptosar) O
O
C
N
D
E
C
O
N HO
D
E
O O
O N
N
N
O
HO
HO N
O
N
S-phase specific
Administration : IV
Administration: IV
Indications: metastatic carcinoma of ovary and small cell lung carcinoma as secondary lines of treatment.
Indications: metastatic colon carcinoma that has recurred following 5-FU therapy
Side Effects and Toxicity: myelosuppression (neutropenia with or without thrombocytopenia), nausea and vomiting, fever, fatigue, rash
Side Effects and Toxicity: severe diarrhea (late onset variety can be life threatening), neutropenia 83
Topoisomerase II
Cellular Activities: 1. Unknotting, relaxation, and decatanation of DNA 2. Principal cellular function is to mediate the separation of sister chromatids during mitosis 84
85
Topoisomerase II: Jekyll and Hyde
86
Topoisomerase II: Jekyll and Hyde
87
Etoposide (VePesid, VP-16)
Teniposide (Vumon, VM-26) OH
OH H3 CO
H3 CO
OCH3
H
H
O
O
O
O
O O
O
H
O
O O
O
OH
O
O
O
O
OCH3
S
O
H
OH OH
OH
Administration: IV or PO
Administration: IV
Indications: refractory testicular tumors and small cell lung carcinoma
Indications: ALL
Side Effects and Toxicity: bone marrow suppression, anaphylactic reaction (chills, fever, bronchospasms, tachycardia), impairment of fertility, mutagenic and carcinogenic, nausea and vomiting, hypotension, alopecia.
Side Effects and Toxicity: bone marrow suppression, hypersensitivity, secondary malignancies, mutagenic and carcinogenic, mucositis, nausea and vomiting, acute CNS depression 88 and hypotension
Etoposide and Teniposide SAR OH H 3CO
OCH 3
4
E
H O A O O R
B
C
O
O
O
O D O
H
OH
Etoposide and Teniposide are synthetic derivatives of the epipodophyllotoxins; cell cycle S and G2 phase specific. Modifications that increase etoposide and teniposide affinity for Topoisomerase II Include: 1. Demethylation and subsequent hydroxylation at position C-4 of the E ring 2. The presence of the glucopyranose moiety on the C ring overall planar structure of tetracyclic core is important for the interaction with the DNA - topoisomerase II cleavage complex
OH Resistant tumor cells have increased P-glycoprotein efflux transporter; mutation or decreased expression of topoisomerase II; mutations in p53 tumor suppressor gene (apoptotic pathway). 89
6. Hormones and Related Agents A. Adrenocorticosteroids Prednisone Dexamethasone Aminoglutethimide (inhibitor) B. Progestins Medroxyprogesterone acetate Megestrol acetate
General Note for Category A: • Lympholytic effects and suppression of mitosis in lymphocytes. • Useful as cytotoxic agents in treatment of acute leukemia in children and malignant lymphoma in children and adults General Note for Category B: • Useful for treatment of neoplasms of the prostate and breast because these organs are dependent upon hormones for growth, function and morphology.
C. Estrogens and Androgens Androgen-deprivation therapy Goseralin Leuprolide Aromatase Inhibitors Exemestane Anastrozole Letrozole SERMS (Selective Estrogen Receptor Modifiers) Tamoxifen Raloxifene
90
91
O
H H H
H
Cholesterol
H
H
Aldosterone
OH
O HO
H
O
H
O
Progesterone
H
OH
H
O
HO
O
HO
H
H H
O
H
OH OH
H H
H
Testosterone
O
H
Cortisol
OH H H
H
HO
Estradiol
• activates the synthesis/release of glucose into the bloodstream • involved in immunosuppression blocks the inflammatory response (transcriptional repression of cytokines in lymphocytes) 92
Glucocorticoid Receptor Cortisol HSP90 GR GR
Hormone binding Domain
DNA Binding Domain
Cytoplasm Nucleus
HSP90 Homodimer
Transcriptional Machinery of Repressor Proteins
GR GR GR GR GRE Glucocorticoid Response Element (sequence specific binding motif)
Gene Expression Gene Repression 93
A. Agonists of the Glucocorticoid Receptor
Leukemia cells grown in culture - Growth Factors and Cytokines (PDGF, ILGF, IL-2, IL-3, etc)
Apoptosis (Programmed Cell Death) p53 - Independent (NOT Required)
+ Growth Factors and Cytokines
Healthy Cells
Hypothesis: Drugs that mimic cortisol are useful in the chemotherapy of lymphoblastic leukemias and lymphomas because they predispose lymphocytes to undergo apoptosis. 94 (in vivo this is more selective for tumor cells than for normal cells)
A. Agonists of the Glucocorticoid Receptor Prednisone (Deltasone, Orasone)
Dexamethasone (Decadron)
Administration: PO Administration: PO Indications: multiple; primary treatment of childhood leukemias, less successfully in the palliative management of adult leukemias and lymphomas Side Effects and Toxicity: drug induced adrenal corticosteroid insufficiency, high blood glucose; immunosuppression, increased appetite and salt retention; depression upon withdrawal
Indications: palliative treatment of adult leukemias and for childhood ALL; multiple myeloma, in which dexamethasone is given alone or together with thalidomide (thal-dex) or a combination of adriamycin and vincristine (VAD). Side Effects and Toxicity: same as for prednisone.
95
B. Progestins Medroxyprogesterone acetate
Hypothalamus Progesterone (-)
Estradiol (-,+)
X
GnRH
Anterior Pituitary Inhibin (-)
LH,FSH LH
CL
X
LH, FSH
X
Estradiol
Follicle
Ovary 96
B. Progestins Medroxyprogesterone acetate (Depo-provera) O
Megestrol acetate (Megace) O O
O H H
H O
H
H
O
Administration: PO Indications: breast cancer, endometrial cancer, and to a lesser extent renal cancer Side Effects and Toxicity: thrombophlebitis, pulmonary embolism, retinal embolism, CNS symptoms (headache, dizziness), mild fluid retention.
O H
O
Administration: PO Indications: breast cancer, less frequently for endometrial cancer and prostate cancer Side Effects and Toxicity: weight gain, vaginal bleeding, may cause acute hypercalcemia in patients with bone metastases.
Pharmacology: 97 inhibit release of gonadotrophin releasing hormone; inhibit cellular proliferation - not cell cycle phase-specific, but maximal in G1 phase
C. Estrogens and Androgens Androgen Deprivation Therapy
Hypothalamus NH 2 HN H N
O
H N
N H N
O N H
GnRH
O
O N H
OH H N O NH
O
H N
N H
O
GnRH
O N H
H N
N O
O
Anterior Pituitary
OH
Leuprolide (GnRH agonist)
X FSH
X
Androgens (Testosterone) LH
Interstitial Cells Spermatogenesis After 2 weeks of treatment
98
Androgen Deprivation Therapy Leuprolide Acetate (Lupron, Eligard, Viadur) NH 2 H N
O
H N
N H N
O N H
O
HN
D-Leu
O N H
OH H N O NH
O N H
H N O
O N H
H N
N O
O O
OH
O-
Administration: IM, SC, depot Indications: palliative treatment of advanced prostate cancer Pharmacology: GnRH agonist - inhibit gonadotropin release from the anterior pituitary; selective for FSH and testosterone. Side Effects and Toxicity: worsening signs and symptoms during the first two weeks, hot flashes, and sexual dysfunction.
99
Aromatase Inhibitors
(aromatase)
X
100 Miller, WR. Semin Oncol. 2003 Aug;30(4 Suppl 14):3-11. Aromatase inhibitors: mechanism of action and role in the treatment of breast cancer.
Aromatase Inhibitors Exemestane (Aromasin) O Structurally-related to androstenedione
H H
H
O Administration: PO Indication: postmenopausal patients with hormone-dependent breast cancer; adjuvant treatment following tamoxifen treatment for early stage cancer (2005), or advanced cancer which has progressed following tamoxifen therapy (1999). Pharmacology: highly selective, irreversible aromatase enzyme inactivator, reduces amount of circulating estrogens by 85-95%. Side Effects and Toxicity: hot flashes, nausea, fatigue, increased sweating, and increased appetite
101
Letrozole (Femara)
Anastrozole (Arimidex) a, a, a', a'-tetramethyl-5-(1H-1,2,4-triazol-1ylmethyl)-1,3-Benzenediacetonitrile
4,4'-(1H-1,2,4 -Triazol-1-ylmethylene) dibenzonitrile
N
N
N
N
N
N
NC CN
CN
NC
Administration: PO Pharmacology: potent, selective non-steroidal aromatase inhibitor (binds heme of the cytochrome P450 subunit) Indication: postmenopausal patients with hormone-dependent breast cancer; adjuvant treatment following tamoxifen treatment for early stage cancer (2005), or advanced cancer which has progressed following tamoxifen therapy (1999). Side Effects and Toxicity: hot flashes, nausea, decreased energy and weakness, joint pain, muscle pain, bone pain
102
Selective Estrogen Receptor Modifiers (SERM) Targets of Estrogen: Breast Endometrium Bone Blood
associated with Increased cancer risk maintains bone density effects on blood coagulation? (thromboembolism side effect)
Effects of Tamoxifen: Breast Endometrium Bone Blood
Antagonist Decreased cancer risk Increased cancer risk maintains bone density Agonist effects on blood coagulation? (thromboembolism side effect)
103
Estrogen Receptor Estradiol HSP90 ER ER
Two family members of The Estrogen Receptor (alpha and beta) expressed differentially in different tissues
Cytoplasm Nucleus
HSP90 Homodimer
Tissue specific expression of different ER binding cofactors
ER ER ER ER ERE
Gene Expression
Estrogen Response Element (sequence specific binding motif) Sequence variations in the ERE may cause differential activation
Gene Repression 104
Tamoxifen Citrate (Nolvadex Istubal, Valodex) nonsteroidal triphenylethylene derivative
O
O
N
N H
active metabolite? world's largest selling breast cancer treatment Administration: PO Indications: metastatic breast cancer, adjuvant therapy of breast cancer, and chemoprevention in high risk women Pharmacology: selective estrogen receptor modifier; specific for mid-G2 phase Side effects and toxicity: hypercalcemia can occur in women that have bone metastasis, increased risk of endometrial cancer (3-6 fold), thrombosis and pulmonary embolisms. 105
106
Estrogen Receptor Tamoxifen Acts as a competitive inhibitor
Estradiol HSP90 ER ER
Hormone binding Domain
DNA Binding Domain
Cytoplasm Nucleus
HSP90 Homodimer ER ER ER ER ERE
Transcriptional Machinery of Repressor Proteins
X
X
Gene Expression
Estrogen Response Element (sequence specific binding motif) Gene Repression 107
HYPOTHESIS: Tamoxifen alters the structure of the ligand binding domain of the estrogen receptor so that cofactors required for transactivation cannot bind with the receptor 108
7. Cancer Immunotherapy 1. Passive Immunotherapy injection of monoclonal antibodies to stimulate the immune system’s attack on cancer cells; may be conjugated to toxin, radioisotope or cytokine
2. Biological Response Modifiers immunization of the patient patient's own immune system is trained to recognize tumor cells as targets to be destroyed
109
Monoclonal antibodies for cancer. ADEPT, antibody directed enzyme prodrug therapy; ADCC, antibody dependent cell-mediated cytotoxicity; CDC, complement dependent cytotoxicity; MAb, monoclonal antibody; scFv, single-chain Fv fragment. Modified from Carter P: Improving the efficacy of antibody-based cancer therapies. Nat Rev Cancer 2001;1:118-129 110
Trastuzumab (Herceptin-R)
Administration: IV Indications: metastatic breast cancer ( in tumors that only overexpress the tyrosine kinase receptor (HER-2 or erb B2); single agent or in combination with paclitaxel Pharmacology: humanized monoclonal antibody that selectively binds to the extracellular domain of the human epidermal growth factor receptor2 protein, HER2; inhibits the proliferation of cells expressing HER-2/erb B2 Side Effects and Toxicity: cardiomyopathy (especially if administered in combination with anthracycline antibiotics), hypersensitivity, increased neutropenia when given in combination with other chemotherapeutics
111
Cardiotoxicity of Trastuzumab
Nature Reviews Cancer 7, 332-344 (May 2007)
112
Gemtuzumab Ozogamicin (Mylotarg) Administration: IV Indications: treatment of CD33 positive acute myeloid leukemia in patients (60+ years) who are not considered candidates for cytotoxic chemotherapy. Accel. Approv. (clinical benefit not established) May 2000. Pharmacology: recombinant humanized antibody conjugated with cytotoxic antitumor antibiotic calicheamicin; antibody portion binds specifically to the CD-33 antigen on the surface of leukemic blasts and immature normal cells of myelomonocytic lineage, but not on normal hematopoietic stem cells. Side Effects and Toxicity: severe myelosuppression – neutropenia, thrombocytopenia; hepatotoxicity; hypotension, rigors, fever, shortness of breath, bronchospasm, chills, and/or rash resolved after 2 to 4 hours with a supportive therapy of acetaminophen, diphenhydramine, and IV fluids. 113
Boghaert, E. R. et al. Clin Cancer Res 2004;10:4538-4549 Copyright ©2004 American Association for Cancer Research
114
Calicheamicin isolated from fermentation of Micromonospora echinospora ssp. calichensis
mixture of products 1 is major
DNA double strand cleavage 115
>1,000 times more potent than adriamycin (doxorubicin); binds to minor groove of DNA
Thalidomide (Thalomid)
May 2006
Administration: IV Indications: in combination with dexamethasone for the treatment of newly diagnosed multiple myeloma. Pharmacology: immunomodulatory agent (stimulates T-cells); anti-angiogenic (blocks bFGF and VEGF); inhibition of the growth/ survival of stromal cells, tumor cells and bone marrow cells; alters production/activity of cytokines Side effects and toxicity: teratogenic, peripheral neuropathy, fatigue, constipation; increased risk of deep vein thrombosis.
116
GARDASIL • a prophylactic HPV vaccine
Merck FDA approved June 2006
• protects against four types of human papillomavirus, which account for the vast majority of the 500,000 cervical-cancer cases and the 32 million new cases of genital warts around the world each year. • HPV-16 and HPV-18 are responsible for about 70% of the cases of cervical cancer worldwide. • HPV-6 and HPV-11 cause approximately 90% of the cases of genital warts. Indications • recommended that girls receive the vaccine prior to becoming sexually active. • women already infected with 1 or more HPV types targeted by the vaccine are protected from clinical disease caused by the remaining HPV types in the vaccine. • will not block infection with all HPV types that can cause cervical cancer; should not be considered a substitute for routine Pap smears. 117
Nature Reviews Cancer 7, 11-22 (January 2007)
HPV major capsid protein L1 can spontaneously self-assemble into virus-like particles (VLPs). Gardasil contains recombinant VLPs assembled from the L1 proteins of HPVs 6, 11, 16 and 18. Since VLPs lack the viral DNA, they cannot induce cancer. 118
8. Signal Transduction Inhibitors A. Receptor Tyrosine Kinase Inhibitors Imatinib mesylate Gefitinib Erlotinib hydrochloride Lapatinib ditosylate Sunitinib maleate Sorafenib tosylate Pazopanib
B. Proteasome Inhibitors – Bortezomib C. Drugs Targeting Transcription Factors (Multifunctional Drugs) Tretinoin Bexarotene Synthetic Oleanane Triterpenoids
D. Drugs Targeting Epigenetic Factors Zolinza (HDAC inhibitor) Decitabine DNMT inhibitors Azacitidine
E. Antisense Therapy – Genasense
119
A. Receptor Tyrosine Kinase Inhibitors Imatinib mesylate (Gleevec)
Administration: PO Indications: Philadelphia chromosome positive chronic myeloid leukemia (CML) in early phase, blast crisis, accelerated phase; Ph+ ALL; CMML; KIT (CD117) positive unresectable and/or metastatic malignant gastrointestinal stromal tumors (GIST). Pharmacology: protein-tyrosine kinase inhibitor that inhibits the BCR-ABL tyrosine kinase; it inhibits proliferation and induces apoptosis in BCR-ABL positive cell lines; also inhibits KIT and PDGFR Side Effects and Toxicity: cardiotoxicity, oedema, myelosuppression, diarrhea, rash, acne, dry skin, nausea, vomiting
120
Most Cases of CML (Chronic Myelogenous Leukemia)
Transcription and translation of the hybrid BCR-ABL gene produces an abnormal ("fusion") protein that activates constitutively (all the time) a number of cell activities that normally are turned on only when the cell is stimulated by a growth factor, 121 such as platelet-derived growth factor (PDGF).
HSC BP CP CMP CLP GMP MEP Nat Rev Cancer. 2005; 5(3):172-183
Hematopoietic Stem Cells blast phase chronic phase common myeloid progenitors common lymphoid progenitors Granulocyte/macrophage “ Megakaryocyte/erythrocyte 122“
123 Weisberg et. al. Nature Reviews Cancer 7, 345-356 (May 2007)
Cardiotoxicity of Imatinib
124 Nature Reviews Cancer 7, 332-344 (May 2007)
Novel tyrosine kinase inhibitors for CML in clinical trials. Dasatinib INNO-406 MK-0457 Nilotinib Bosutinib AZD0530 PHA-739358
approved phase I phase II phase II phase II phase II phase II 125
Weisberg et. al. Nature Reviews Cancer 7, 345-356 (May 2007)
Imatinib Resistance •
may develop in advanced phases of CML and Ph+ ALL
•
due to point mutations in BCR-ABL enzyme (reduce sensitivity to imatinib): i.
mutations clustered around imatinib binding site change binding affinity for imatinib by altering lypophilic and H-bond interactions or introducing steric hindrance.
OR ii. mutations affect binding mode of drug to enzyme – destabilize inactive conformation of ABL kinase domain, to which imatinib binds. •
more than 50 different imatinib-resistant BCR-ABL mutations have been identified.
•
Point mutations may pre-exist in newly diagnosed patients or be acquired through selective pressure of imatinib.
•
Note that imatinib does not deplete leukaemic stem cells.
•
126 Strategies to circumvent resistance include combination therapy for multiple targets.
Weisberg et. al. Nature Reviews Cancer 7, 345-356 (May 2007)
Inactive kinase conformation
Active kinase conformation
P-loop A-loop
127
P-loop: bent over inhibitor A-loop: 'DFG-out' conformation
127 P-loop: extended conformation A-loop: 'DFG-in' conformation
Gefitinib (Iressa)
Administration: PO Indications: monotherapy for the treatment of patients with locally advanced or metastatic NSCLC after failure of both platinum-based and docetaxel chemotherapies; Accel. Approv. (clinical benefit not established). Pharmacology: inhibits EGFR tyrosine kinase by binding to ATP-binding site: function of the EGFR tyrosine kinase in activating the Ras signal transduction cascade is inhibited Side Effects and Toxicity: diarrhea, rash, acne, dry skin, nausea, vomiting; low cardiotoxicity
128
TGF EGF
inactive monomeric receptor to active homodimer
Ire ss a
• • • •
autophosphorylation elicits downstream activation and signaling. downstream signaling proteins initiate signal transduction cascades (Ras etc) lead to DNA synthesis and cell proliferation. 129 inhibitors such as Iressa prevent autophosphorylation by binding to cytoplasmic domain
Erlotinib Hydrochloride (Tarceva) N N
O O
Pfizer
O O
NH
Administration: PO Indications: locally advanced or metastatic NSCLC after failure of at least one prior chemotherapy regimen (November 2004); in combination with gemcitabine for the first-line treatment of locally advanced, unresectable or metastatic pancreatic cancer (November 2005) Pharmacology: inhibits autophosphorylation of the cytoplasmic tyrosine kinase domains of HER1/EGFR - no activation of the downstream signal transduction pathways, stopping growth Side Effects and Toxicity: diarrhea, rash, acne, nausea, vomiting, interstitial lung disease; low cardiotoxicity
130
Lapatinib Ditosylate (Tykerb)
Glaxo SmithKline FDA approval: March 13, 2007
Administration: PO (1250 mg/day = five tablets, one dose) Indications: for use in combination with capecitabine (Xeloda®) for the treatment of patients with advanced or metastatic breast cancer whose tumors overexpress HER2 (ErbB2) and who have received prior therapy including an anthracycline, a taxane, and trastuzumab (Herceptin®). Pharmacology: EGFR and ErbB-2 (Her2/neu) dual tyrosine kinase inhibitor. It binds to the intracellular phosphorylation domain to prevent receptor autophospohorylation upon ligand binding. 131
Side Effects and Toxicity: diarrhea, rash, nausea and vomiting; low cardiotoxicity
Sunitinib Maleate (Sutent)
Pfizer
Administration: PO Indications: treatment of gastrointestinal stromal tumor after disease progression on or intolerance to imatinib mesylate; advanced renal cell carcinoma: Accel. Approv. (clinical benefit not established) January 2006. Pharmacology: inhibitor of multiple receptor tyrosine kinases including VEGFR, PDGFR and the KIT receptor Side Effects and Toxicity: cardiotoxicity, hemorrhage, hypertension, adrenal dysfunction, hypothyroidism, fatigue, myelosuppresion and gastrointestinal upset
132
ANGIOGENESIS
133 Nature Reviews Cancer 3, 401-410 (2003);
Nature Reviews Drug Discovery 6, 273-286 (April 2007)
Sorafenib tosylate (Nexavar) F
F
F
Bayer
O
Cl
O
O N H
N H
N
N H
O S OH O
Administration: PO Indications: advanced renal carcinoma (December 2005) Pharmacology: inhibits RAF kinase, VEGFR tyrosine kinase, PDGFR tyrosine kinase (multiple intracellular and cell surface kinases). Side Effects and Toxicity: cardiotoxicity, skin rash, diarrhea, hypertension, hemorrhage
134
Pazopanib H N
N
CH3 N
N
H3 C O S NH 2 O
Investigational Drug
N N CH 3
.HCl
Note: Axitinib is another investigational antiangiogenic drug
CH 3
Administration: PO Pharmacology: inhibitor of VEGFR (inhibits angiogenesis and tumor growth)
135 Podar et al. PNAS.2006; 103: 19478-19483
B.
Proteasome Inhibitors
Bortezomib (Velcade)
O N
N H
N
H N
OH B OH
O
Administration: IV Indications: multiple myeloma patients who have received as least one prior therapy Pharmacology: potent, reversible inhibition of 26S proteasome: multicatalytic enzyme whose function is to degrade abnormal or misfolded proteins targeted for destruction Side Effects and Toxicity: peripheral neuropathy; myelosuppression – neutropenia and thrombocytopenia; 136 fatigue, nausea, diarrhea, weight loss
137
C. Drugs Targeting Transcription Factors (Multifunctional Drugs) Retinoids, Rexinoids and Triterpenes – used to prevent and treat cancer in animal models – could be synergistic with other anti-cancer agents
Figure 1. Mechanisms by which chimeric transcription factors can lead to cellular transformation.
138 Salomoni & Pandolfi Nature Medicine 6, 742 - 744 (2000)
Tretinoin (Vesanoid, ATRA) (all trans-retinoic acid; first generation retinoid)
O OH
Administration: PO Indications: induces remission of APL refractory to anthracyclines; topical treatment for basal cell carcinoma; acute PML Pharmacology: normal metabolite of vitamin A; induces cytodifferentiation and decreased proliferation of APL cells Side effects and toxicity: skin/mucous membrane dryness, teratogenic, severe headache, fever, weakness, and fatigue, bone pain, nausea, vomiting, rash, cerebral and GI hemorrhage
139
Bexarotene (Targretin, LGD1069) third generation rexinoid
OH O
Administration: PO Indications: cutaneous T-cell lymphoma; in clinical trials for breast and lung cancers Pharmacology: selective for retinoid X receptors; much less flexible than previous generation drugs therefore more specific binding. Side effects and toxicity: reduced toxicity cf tretinoin but still retains some toxicities associated with binding to RARs
140
Oleanane Triterpenoids
Natural product
E
12 C
Synthetic oleananes
3
most potent anti-carcinogenic triterpenoids known?
O C
NC
HO
A
OH
13
28
O Oleanolic acid
E
R
A
O
CDDO: CDDO-Me: CDDO-Im: CDDO-MA: CDDO-EA: Di-CDDO:
R = COOH R = COOMe R = CO-imidazole R = CONHMe R = CONHEt R = CN 141
Triterpenoids can protect cells and tissues from stress (inflammatory, metabolic, oxidative and nitrosative) by increasing the transcriptional activity of NRF2. 142 Nature Reviews Cancer 7, 357-369 (May 2007)
143
Nature Reviews Cancer 7, 357-369 (May 2007)
D. Epigenetic Factors that Cause Tumorigenesis
Dynamic, heritable changes in genes (activation and silencing) – no change in DNA sequence – association of DNA with histones (modifications regulate transcription): e.g. histone acetyltransferases (HAT) histone deacetylases (HDAC) – DNA methylation
Suzuki T, Miyata N. Current Medicinal Chemistry 2006, 13, 935-958 Epigenetic Control Using Natural Products and Synthetic Molecules
144
Role of Histone Deacetylase/Acetylase
Minucci S (2006) Nat. Rev. Cancer. 6: 38–51
Sustained HDAC activity results in histone hypoacetylation, tightly packaged chromatin, and dysregulation of gene transcription (e.g. silences tumor suppressor gene p53, and cyclin-dependent kinase inhibitor p21).
O H HN
O N H
O H
HDAC CH3
HAT
HN
NH3+
145
146 Minucci S (2006) Nat. Rev. Cancer. 6: 38–51
Zolinza (Vorinostat) (Suberoylanilide hydroxamic acid, SAHA)
O
N H N
ZBG
cap
O OH
linker
Administration: PO Indications: Advanced cutaneous T-cell lymphoma (progressive, persistent, or recurrent disease on or following two systemic therapies). Pharmacology: HDAC inhibition causes histone hyperacetylation, transcriptional activation of genes associated with cell cycle progression and differentiation (p21, caspase-3). Side effects and toxicity: pulmonary embolism (blood clot in the lungs), dehydration, deep vein thrombosis; anemia; gastrointestinal symptoms (diarrhea, nausea, anorexia, vomiting and 147 constipation); fatigue; chills; taste disorders.
Agent/stage of development
Structural class
HDAC targets
Zolinza (vorinostat; SAHA)/FDA approval for CTCL
Hydroxamate
Class I and II
Romidepsin (depsipeptide)/phase 2b for CTCL and PTCL
Bicyclic peptide
Class I
MS-275/phase 2
Benzamide
Class I
MGCD0103/phase 2
Anilide
Class I
PXD101/phase 2
Hydroxamate
Class I and II
Baceca/phase 2
Short chain fatty acid
Class I
Savicol/phase 2
Short chain fatty acid
Undisclosed
LBH589/phase 1
Hydroxamate
Class I and II
PCI-24781/phase 1
Hydroxamate
Class I and II
ITF2357/phase 1
Undisclosed
Undisclosed
148
Nature Biotechnology - 25, 17 - 19 (2007)
DNA Methylation genes silenced by DNA methylation can lead to suppression of tumor growth or sensitization to anticancer therapies i.e. DNA methylation dysregulates gene transcription.
149
Decitabine (Dacogen)
Azacitidine (Vidaza)
NH 2
FDA approval May 2006
N
N N N
N
O
HO
N O
FDA approval May 2004
NH 2
O
HO O
Administration: IV
OH OH OH
Indications: myelodysplastic syndromes (MDS) including refractory anemia, refractory anemia with ringed sideroblasts, refractory anemia with excess blasts, refractory anemia with excess blasts in transformation, and chronic myelomonocytic leukemia Pharmacology: incorporate into DNA and inhibit DNA methyltransferase, resulting in hypomethylation of DNA and intra-S-phase arrest of DNA replication.
Side effects and toxicity: Neutropenia, thrombocytopenia, anemia, fatigue, pyrexia, nausea, cough, petechiae, constipation, diarrhea, hyperglycemia
150
E. Antisense Therapy Genasense (BCL2 antisense oligonucleotide, oblimersen sodium ) 18-mer phosphorothioate oligonucleotide designed to bind to the first six codons of the human Bcl-2 mRNA
Administration: IV Indications: pre-treatment (4-7 days prior to chemotherapy) in cancers over-expressing BCL-2 (most cancers) e.g. melanoma and CLL. Pharmacology: restores apoptotic pathways by blocking the production of BCL-2 protein: sensitizes cancer cells to standard chemotherapy (imatinib, daunorubicin, etoposide); may also inhibit angiogenesis Side effects and toxicity: low-grade fever and fatigue
151
Note: Genta filed an appeal (April 4, 2007) to the recent non-approvable decision by the FDA for the Company's NDA which proposed the use of Genasense in combination with chemotherapy for treatment of patients with relapsed or refractory chronic lymphocytic leukemia (CLL).
BCL-2 blocks the release of cytochrome C from the mitochondria: cytochrome C triggers the activation of caspases cell death
152
Summary
153
Knowledge of Genetic Defects in the Development of Cancer Affects Cancer Treatment
•
Provides new therapeutic targets
•
Allows development of new chemotherapeutic agents that have more directed therapies.
•
Increases ability to more accurately predict a patient’s prognosis
•
design better treatment strategies based on the types of mutations present within a tumor.
•
Potentially less toxic chemotherapy since target selective. 154
Treatment Strategies for Combination Chemotherapy
1. Utilize drugs that have been shown to possess antitumor activity when used alone 2. Utilize drugs that have non-overlapping toxicities and/or produce relevant toxicities during different times after treatment 3. Utilize drugs that have different mechanisms or targets of action and/or, do not display cross-resistance
The National Cancer Institute Cancer Centers Program http://www.cancer.gov/cancertopics/factsheet/NCI/cancer-centers
155
Treatment of Lymphoma and Leukemia Some Success Stories:
MOPP - Mechlorethamine, Vincristine (Oncovin), Procarbazine, Prednisone Used for treatment of Hodgkins with 80% complete remission POMP - Prednisone, Vincristine (Oncovin), Methotrexate, Mercaptopurine (Purinethol) Used for treatment of ALL - 90% complete remission COAP - Cyclophosphamide, Vincristine (Oncovin), Cytarabine (Ara-C), Prednisone Used for treatment of AML - 47% remission rate
156
Treatment of Colon Cancer Stage I and II (localized to the colon) 1. Surgical resection Stage III (lymph node involvement) 1. Surgical resection of primary tumor and regional lymph nodes followed by adjuvant chemotherapy a. 5-FU and levamisole (restores immunosuppression) b. 5-FU and leucovorin c. Capecitabine (Xeloda) d. 5-FU, leucovorin and oxaliplatin (FOLFOX) 2. First line treatment: Avastin and IFL (irinotecan, 5-FU, and leucovorin)
http://www.coloncancerfoundation.org/
157
Breast Cancer Treatment Surgical resection 1. Lumpectomy or Mastectomy Adjuvant Therapy: 1. Radiation Therapy 2. Hormone Therapy - Tamoxifen (most effective in postmenopausal women) 3. Polychemotherapy - most effective in node positive premenopausal women Common chemotherapies used in treatment of breast cancer: CMF - cyclophosphamide ( PO - days 1-14) methotrexate (IV - days 1 and 8) 5-fluorouracil (IV - days 1 and 8) Cycle: 28 days AC - Adriamycin (IV - day 1) Cyclophosphamide (IV - day 1) Cycle: 21 days For early stages I and II, usually use 3 cycles; For metastatic disease 4-6 cycles 158
Breast Cancer Treatment Paclitaxel –combination with adriamycin and cyclophosphamide Docetaxel – treatment after relapses/progression during anthracycline-based treatment Gemicitabine – combination with paclitaxel for the first-line treatment of metastatic breast cancer after failure of anthracycline adjuvant chemotherapy Goserelin acetate – palliative treatment of advanced breast cancer in pre- and perimenopausal women. Tamoxifen – premenopausal women with metastatic breast cancer as an alternative to oophorectomy or ovarian irradiation; axillary node-negative breast cancer adjuvant therapy. Toremifen – advanced metastatic breast cancer in postmenopausal women Anastrozole (Arimidex) Exemestane (Aromasin) Letrozole (Femara)
Hormone receptor positive breast cancer; treatments of choice in postmenopausal women
Trastuzumab (Herceptin) - HER2-positive breast cancer in stage II, III, and IV 159
http://imaginis.com/breasthealth/bc_drugs.asp#Chemotherapy_Regimens
Lung Cancer Treatment Often presents late in course of the disease (Stage III and IV) Cure is rare; Treatment is aimed at controlling disease progression and prolonging life (palliative) Non small cell lung carcinoma chemotherapy, radiation therapy followed by surgical resection For small cell lung carcinoma primary treatment is radiation or chemotherapy; Surgical resection has not been shown to improve survival Three regimens used to treat lung cancer include: CODE - Cisplatin (IV - 1 per week for 9 wks) Vincristine (Oncovin, weekly IV during weeks 1, 2, 4, 6, and 8) Adriamycin (Doxorubicin, weekly IV during weeks 1, 3, 5, 7, and 9) Etoposide (IV on day 1 of weeks 1, 3, 5, 7, and 9) Etoposide (PO, days 2 and 3 of weeks 1, 3, 5, 7, and 9) 160
Lung Cancer Treatment CAP - cyclophosphamide (IV day 1) adriamycin (IV day 1) cisplatin (IV day 1) Cycle: 28 days COPE - Cyclophosphamide (IV day 1) Vincristine (IV day 14) Cisplatin (IV day 2) Etoposide (IV days 1, 2, and 3) Cycle: 21 days Vinorelbine – single agent or combination with cisplatin Paclitaxel – combination with cisplatin, first-line treatment when surgery and/or radiation therapy not indicated Docetaxel – combination with cisplatin for unresectable NSCLC who have not previously received chemotherapy; or after failure of prior platinum-based chemotherapy Erlotinib – single agent after failure of at least one prior chemotherapy regimen Gefitinib – single agent after failure of platinum-based and docetaxel chemotherapies Porfimer sodium – photodynamic therapy where radiation or surgery are not indicated Gemcitabine – combination with cisplatin, first-line treatment inoperable NSCLC Pemetrexed disodium – single agent after prior chemotherapy 161 Topotecan – single agent for chemosensitive disease after failure of first-line treatment
Prostate Cancer Treatment Stage I • radical prostatectomy, usually with pelvic lymphadenectomy, with or without radiation therapy after surgery. • external-beam radiation therapy. • implant radiation therapy. • high-intensity focused ultrasound. • clinical trial of radiation therapy. • clinical trial evaluating new treatment options. Stages 2, 3, 4 • same as above • hormone therapy followed by radical prostatectomy Docetaxel - in combination with prednisone for androgen independent (hormone refractory) metastatic prostate cancer Estramustine - palliation of prostate cancer Histrelin Acetate - palliation of prostate cancer Leuprolide - palliation of prostate cancer Mitoxantrone - in combination with corticosteroids - initial chemotherapy for pain related to advanced hormone-refractory prostate cancer 162 Abarelix - palliation of prostate cancer (NB allergic reaction)
In reviews of more than 150 epidemiological studies, people who consumed about 5 servings of fruits and vegetables daily were half as likely to develop cancer of the digestive and respiratory tracts than those who consumed fewer than 2 servings a day. Cruciferous vegetables - broccoli and cauliflower Legumes - soy beans and other bean varieties Tomatoes - especially concentrated as a paste or pasta sauce Garlic - sliced or crushed for 10-15 minutes prior to cooking and then only light cooking 1-2 minutes Green Tea and Black Tea - Best benefit with longer brewing times Red wine / grapes - Resveratrol (most benefit towards heart disease) Avocados - rich in glutathione, a powerful antioxidant
163
Alternative Cancer Therapies http://www.cancure.org/choiceoftherapy.htm http://www.cancerguide.org/alternative.html http://www.alternative-cancer-treatments.com/ http://www.positivehealth.com/PERMIT/Articles/Cancer/goodman1.htm - diet regimes
ELLAGIC ACID - red berries (raspberries) and pomegranates - scavenges carcinogens AMYGDALIN (Laetrile) - apricot seed extract - used in conjunction with broad-spectrum nutritional program CANCELL/CANTRON (Entele) - lowers overall energy of the body to starve the cancer; the cancer dies from energy starvation and is cleaned up by the immune system ACID/ALKALINE BALANCE - minerals such as calcium, magnesium, potassium, rubidium and cesium neutralize acidity of tumor cells ELECTRONIC THERAPIES - cancer cells have a lower frequency of resonance than normal cells – magnetic resonance therapy; direct electric current causes electrolysis electrochemical therapy 164
