Basic Pharmacology of Cancer Chemotherapies Flashcards
Are alkylating agents cell cycle dependent? How do they work?
NO- they are NOT CELL CYCLE DEPENDENT
they form electrophilic bonds in Guanine of DNA which HALTS CELL REPRODUCTION
What are the Nitrogen Mustards? What drugs are included in this category?
Nitrogen Mustards are ALKYLATING AGENTS
CYCLOPHOSPHAMIDE
Melphalan
Chlorambucil
Hemorrhagic cystitis is a toxicity associated with Cyclophosphamide. What causes the bladder toxicity, and how can it be prevented?
Acrolein is a toxic metabolite of cyclophosphomide that causes hemorrhagic cystitis.
Hemorrhagic cystitis can be partially prevented by the use of MESNA- the thiol group of mesna binds the toxic metabolite
What are the Nitrosureas? What category of anti-cancer drugs do they belong to?
“-MUSTINE” + STREPTOZOCIN
CarMUSTINE
LoMUSTINE
SeMUSTINE
Nitrosureas= ALKYLATING AGENTS
What category of drugs can cross the BBB and are therefore useful for the treatment of brain tumors?
NITROSOUREAS (“-mustine +Streptozocin)
What drug destroys pancreatic beta cells & is used to treat insulinomas?
Streptozocin (Nitrosurea Alkylating Agent)
What category of anti-cancer drugs is Busulfan?
Alkylating Agent (Alkyl Sulfonate)
What is Busulfan primarily used to treat?
CML
Ablation of pt’s bone marrow before BM transplantation
What phase of the cell cycle do Antimetabolites target?
S-PHASE
Highly toxic to rapidly proliferating cells (including normal tissue- hair & GI tract)
What drugs are in the antimetabolite category?
Methotrexate (MTX)
5-Fluorouracil (5-FU)
Cytarabine (ara-C)
Azathioprine
6-Mercaptopurine (6-MP)
6-Thioguanine (6-TG)
What is the mechanism of MTX? Can myelosuppression be reversed?
Folic Acid analog inhibits DHFR–>Decreases THF available for conversion of dUMP–>dTMP–>
Decreased dTMP, DNA & protein synthesis
Myelosuppression IS reversible with LEUCOVORIN (folinic acid rescue)
What is the mechanism of 5-FU? Can myelosuppression be reversed?
PYRIMIDINE analog bioactivated to 5F-dUMP–> covalently complexes to folic acid–>
INHIBITS THYMIDYLATE SYNTHASE–> decrease in dTMP
Myelosuppression is NOT REVERIBLE w Leucovorin
What is the mechanism of Cytarabine (Ara-C)?
Pyrimidine Analog (Cytidine) INHIBITS DNA POLYMERASE
What are the toxicities associated w Ara-C?
Leukopenia
Thrombocytopenia
Megaloblastic Anemia
Azathioprine, 6-MP, & 6-TG all share the SAME mechanism of action. What is the mechanism?
What enzyme are these drugs metabolized by? (What drug increases their toxicity?)
PURINE ANALOGS activated by HGPRT & decrease De Novo Purine Synthesis
Metabolized by XANTHINE OXIDASE (Allopurinol increases their toxicity EXCEPT for 6-Thioguanine- 6-TG)
Use 6-TG in pts taking Allopurinol
What is the mechanism of Antitumor Antibiotics? Give examples of antitumor antibiotics
Intercalate DNA strands–> free radical formation
Dactinomycin
Anthracyclines (Doxorubicin, Daunorubicin & Idarubicin)
Bleomycin
What phase of the cell cycle does Bleomycin affect? Mechanism?
G2 & M phase
Complexes with iron & reacts with oxygen–>Induces free radical formation which causes BREAKS in DNA strands
What drugs are Microtubule Inhibitors aka ANTIMITOTICS?
Vinca Alkaloids (Vincristine & Vinblastine)
Paclitaxel & Taxols
What phase of the cell cycle do Vinca Alkaloids (Vincristine & Vinblastine) affect? Mechanism?
M-phase
Bind to TUBULIN & block polymerization of microtubules so that mitotic spindle cannot form.
(Think of Microtubles= M-phase as the VINes of your cells)
What are the toxicities associated with Vincristine & Vinblastine?
Vincristine= NEUROTOXIC (areflexia, peripheral neuritis, paralytic ileus)
VinBLASTine BLASTS Bone marrow (suppression)
What phase of the cell cycle do the Taxenes (Paclitaxel & Docetaxel) act on? Mechanism?
G2 & M-Phase
Bind TUBULIN–> hyperstabilizes polymerized microtubules so the mitotic spindle cannot break down & anaphase can not procede
Does the action of anticancer drugs follow first-order or second- order kinetics?
First Order- rate of elimination is directly proportional to the drug concentration (constant FRACTION of drug is eliminated per unit time)
What is responsible for multidrug resistance of chemotherapeutic agents (ie pumping drugs out of cells)?
P-glycoprotein is an ATP-dependent membrane efflux transporter responsible for pumping drugs out of cells
Cancer Chemotherapy agents commonly associated with stomatitis & esophagitis?
MTX
5-FU
Dactinomycin
Hepatotoxic Chemo agents?
Etoposide
L-Asparaginase
Pancreatitis associated chemo agents?
6-MP
Busulfan
Cyclophosphamide
Cutaneous Toxicity (Hand-Foot Syndrome)
L-Asparaginase
5-FU
Dilsufiram-Type Rxn
Procabazine
What is the antidote that binds to and inactivates the toxic metabolites responsible for cisplatin induced nephrotoxicity?
AMIFOSTINE
Which agent is used to decrease the incidence & severity of doxorubicin-induced cardiomyopathy in pts w metastatic BC who have received a lifetime cumulative Doxo dose >300mg?
DEXRAZOXANE- iron chelating agent
What RXN does DHFR catalyze?
Conversion of folic acid to tetrahydrofolic acid (active form)
What drug is used as a “rescue medication” in pts taking MTX?
Leucovorin
acts as an active form of folic acid (replenishing the folate pool) that has bypassed the inhibited DHFR & is more readily taken up by normal cells than by malignant cells
What are the adverse effects of MTX?
Stomatitis
BMS
Urticaria
Alopecia
NVD
Nephrotoxicity
Hepatotoxicity
Pulmonary Toxicity
Neurotoxicity
What immunosuppressive drug becomes active only after being converted to 6-MP?
Azathioprine
What enzyme activates 6-MP to its corresponding nucleotide form by adding a ribose phosphate to its structure?
Hypoxanthine-Guanine Phosphoribosyl Transferase (HGPRT)
What are the major s/e of 6MP?
NVD
Hepatotoxicity
BMS
Are the antitumor antibiotics CCS (Cell Cycle Specific)?
Yes- S Phase
What is the MOA of Anthracycline Antibiotics?
inhibition of DNA topoisomerase 2
formation of free radicals–> DNA strand breaks DNA intercalation Inhibition of DNA & RNA synthesis
Give example of anticancer alkylating agents:
Cyclophosphamide
Isofosfamide
Mechlorethamine
Nitrosoureas (-mustine + Streptozotocin)
Cisplatin & Carboplatin
What plant are the vinca alkaloids derived from?
Periwinkle plant
Which plant is paclitaxel a derivative of?
Needles of the Western or Pacific Yew Tree
What are the adverse effects of Paclitaxel?
Neutropenia
Alopecia
Hypersensitivity RXNs
What adverse s/e doe vincristine & vinblastine have in common? Are they vesicants?
NVD
Alopecia
Phlebitis
Cellulites
They are STRONG Vesicants
How are hypersensitivity rxns prevented in pts receiving paclitaxel cancer chemotherapy?
Pretreatment w DIPHENHYDRAMINE & DEXAMETHASONE
Give 2 examples of epipodophylotoxin cancer chemotherapeutic agents
- Etoposide
- Teniposide
What is the MOA of the epipodophyllotoxin cancer chemotherapeutic agents?
Inhibition of DNA topoisomerase 2–> increase DNA degradation
Give 2 examples of chemotherapeutic agents that inhibits DNA topoisomerase 1
- Topotecan
- Irinotecan
What is the MOA of L-asparaginase?
Hydrolyzes asparagine to aspartic acid & ammonia, thereby depriving tumor cells of asparagine required for protein synthesis
Give a brief summary of what happens during each of the following phases of the cell cycle.
What cancer drugs act at each phase?

G0- Cells are not actively dividing (resting state)
G1- Enzymes & proteins required for DNA replication are synthesized
S- Replication of DNA (ANTIMETABOLITES & ETOPOSIDE)
G2- Enzymes & proteins required for mitosis are synthesized (BLEOMYCIN & ETOPOSIDE)
M- Mitosis Occurs (VINCA ALKALOIDS & TAXOLS)
What is the MOA of Bavacizumab? What is its clinical use?
Monoclonal antibody against VEGF- inhibits angiogenesis
used for solid tumors
What is the MOA of VEMURAFENIB?
small molecule inhibitor of forms of the B-Raf kinase with the V600E mutation
used for METASTATIC MELANOMA
MOA of RITUXIMAB?
Clinical Use?
Monoclonal antibody against CD20 (found on most B-cell neoplasms)
Used for Non-Hodgkin’s Lymphoma & RA (w MTX)
MOA of IMATINIB?
Clinical Use?
S/E?
Philadelphia chromosome bcr-abl TYROSINE KINASE inhibitor
Use for CML, & GI stromal tumors
Toxicity= Fluid Retention
What is the major toxicity associated with TRASTUZUMAB (Herceptin)?
CARDIOTOXICITY
What is the MOA of Trastuzumab? What type of cancer is it useful for?
Monoclonal antibody against HER2 (Human Epidermal growth factor Receptor 2) (c-erbB2) a TYROSINE KINASE
Usesful to kill HER-2 positive breast cancer cells that overexpress HER-2, possibly through antibody-dependent cytotoxicity
What is the MOA of Tamoxifen & Raloxifene?
SERMs- receptor blockers in breast & agonists in bone (promote bone growth)
Block the binding of estrogen to estrogen receptor-positive cells
Which SERM increases the risk of endometrial cancer?
TAMOXIFEN due to its partial agonist activity in endometrium
(Raloxifene has no increased risk of endometrial carcinoma because it is an endometrial antagonist)
MOA of Hydroxyurea?
inhibits RIBONUCLEOTIDE REDUCTASE
decreases DNA Synthesis
S-Phase Specific