10/9 Flashcards
Antineoplastic Agents Mechanisms of Action
Kill cells by apoptosis and necrosis
- Promote DNA and RNA damage
- Inhibit DNA repair
- Disrupt cellular metabolism
- Interfere with tubulin assembly/disassembly process
Normal cells affected by antineoplastic agents
Kills normal cells with a high grade fraction
- Gastrointestinal mucosa
- Bone marrow cells: often the dose limiting factor, want to avoid excess neutropenia and thrombocytopenia, should use CSF
- Hair follicles
- Ovaries
Cell Cycle Specific Agents
Depend on the duration of exposure
G1: steroid hormones, asparaginase
S: antimetabolites like methotrexate, 5-fluorouracil, 6-mercaptopurine
Often feature myelosuppression
G2: bleomycin, etopside
M: vinca alkoids like vincristine, taxanes like paclitaxel
Cell Cycle Non-specific Agents
Cumulative dose is important
- Alkylation Agents- feature myelosuppression
Nitrogen mustards: cyclophosphamide
Nitrosoureas: carmustine - Anthracycline antibiotics: doxorubicin, daunorubicin
- Monoclonal antibodies: rituximab
- Tyrosine kinase Inhibitors: imatinib
Cell Cycle Specific Agents: Glucocorticoid
- Class: Hormones
- Prototype: Glucocorticoid (Prednisone, dexamethasone)
- Mechanism of Action: G1, induce apoptosis in lymphoid malignancies
- Adverse Effects: body fluid retention, Hyperglycemia, weight gain, euphoria, confusion
- Indications: leukemia, lymphoma, myeloma, breast cancer , brain metastasis, spinal cord compression
Cell Cycle Specific Agents: Gonadal Hormones
- Class: Hormones
- Prototype: diethykstilbestrol, testosterone
- Mechanism of Action: G1, cytostatic rather than cytocidial, long term administration
- Adverse Effects-
Androgen: cholestatic jaundice
Estrogens: N/V, hypercalcemia, uterine bleeding - Indications-
Androgen: breast cancer
Estrogen: prostate cancer
Cell Cycle Specific Agents: Gonadal Hormone Antagonists
- Class: hormones
- Prototype: tamoxifen, flutamide
- Mechanism of Action- G1
Tamoxifen: estrogen receptor blocker, prevents growth of estrogen receptor positive cells
Flutamide: androgen receptor blocker - Adverse Effects-
Tamoxifen: hot flashes, fluid retention
Flutamide: gynecomastia - Indications-
Tamoxifen: breast cancer
Flutamide: prostate cancer
Cell Cycle Specific Agents: Gonadotropin Releasing Analogs
- Class: hormone
- Prototype: leuprolide, goserelin
- Mechanism of Action: G1 phase, decrease FSH and LH if constant doses
- Adverse Effects: transient flare of symptoms in patients with bone metastasis
- Indications: prostate cancer
Cell Cycle a Specific Agents: Aromatase Inhibitors
- Class: hormones
- Prototype: anastrozole
- Mechanism of Action: G1, inhibits formation of estrogens from androstenedione
- Adverse Effects: nausea, asthenia, headache, hot flashes
- Indications: advanced breast cancer
Cell Cycle specific Agents: L-asparaginase
- Class: misc. antineoplastic agents
- Prototype: L-asparaginase
- Mechanism of Action: G1, catalyze the hydrolysis of Asn to Asp and NH3, depletes serum of Asn which is necessary for lymphoid cells
- Adverse Effects: hypersensitivity, inhibition of protein synthesis leads to decrease in clotting factors, hypoalbumenia
- Indications: lymphoid malignancy, T cell leukemia, T Cell lymphoma
Cell Cycle Specific Agents: Methotrexate
- Class: antimetabolite
- Prototype: methotrexate
- Mechanism of Action: analog of folic acid, inhibits DHFR, compromised DNA replication since depleted A, G, and T
- Adverse Effects: myelosuppression, GI toxicity
- Indications:acute leukemia, breast cancer, non Hodgkin and T Cell lymphoma
Note: folinic acid is routinely given to decrease toxicity, glucarpidase (enzymatically inactivates methotrexate) given to patients with overdose of MTX secondary to decreased MTX clearance from renal insufficiency
Cell Cycle Specific Agents: 6-Mercaptopurine
- Class: antimetabolites
- Prototype: 6-mercaptopurine
- Mechanism of Action: S phase, inhibits purine metabolism following its activation from HGPRT, a purine analog, incorporated into DNA and RNA affecting replication, transcription, and stability
- Adverse Effects: bone marrow suppression
- Indications: acute leukemias (ALL and AML)
Note: resistant cells may lack HGPRT, other purine analogs like thioguanine, adenosine, pentostatin, and azathioprine
Cell Cycle Specific Agents: Cytarabine
- Class: antimetabolites
- Prototype: cytarabine
- Mechanism of Action: S phase, activated by tumor cell kinases to form a nucleotide that inhibits pyrimidine metabolism
- Adverse Effects: bone marrow suppression, N/V, micositis
- Indications: used in regimens for acute leukemias
Note: resistant cells may lack such kinases
Cell Cycle Specific Agents: 5-Fluorouracil
- Class:antimetabolite
- Prototype: 5-fluorouracil
- Mechanism of Action: S phase, activated to a metabolite that inhibits thymidylate synthesis, purine analog, affects DNA/RNA elongation, transcription, and stability
- Adverse Effects: diarrhea, bone marrow suppression, ulcerative stomatitis
- Indications: mainly in the treatment of solid tumors
Cell Cycle Specific Agents: bleomycin
- Class: antibiotics
- Prototype: bleomycin
- Mechanism of Action: G2, Glycopeptide mixture that alters nuclei acid functions via free radical formation
- Adverse Effects: bone marrow sparing, pulmonary fibrosis, skin thickening, hypersensitivity reactions
- Indications: Hodgkin’s and other lymphomas, squamous cell and testicular cancers
Cell Cycle Specific Agents: Etoposid
- Class: plant alkaloid, podophyllotoxin
- Prototype: etoposide
- Mechanism of Action: late S/early G2, topoisomerase II inhibitor
- Adverse Effects: neutropenia, N/V, diarrhea, hepatic dysfunction (high doses)
- Indications: testicular, small cell lung, prostate cancer
Cell Cycle Specific Agents: Vincristine and Vinblastine
- Class: vinca alkaloids
- Prototype: vincristine, vinblastine
- Mechanism of Action: M Phase, binds to tubulin and blocks mitotic spindle assembly, destabilizes the microtubule complex enhancing depolymerization
- Adverse Effects-
Vincristine: neurotoxic
Vinblastine: bone marrow suppression - Indications: acute leukemias, Hodgkin’s and other lymphoma, Kaposi’s sarcoma, neuroblastoma, testicular cancer
Cell Cycle Specific Agents: Paclitaxel
- Class: taxane
- Prototype: paclitaxel
- Mechanism of Action: M Phase, block mitotic spindle disassembly, stabilizes microtubule complex and inhibits depolymerization, opposite of vinca alkaloids
- Adverse Effects: peripheral neuropathy, myelosuppression
- Indications: advanced breast and ovarian cancer
Cell Cycle Non-Specific Agents: cisplatin
- Class: alkylation Agents (platinum coordination compound)
- Prototype: cisplatin
- Mechanism of Action: Covalently binds with DNA at N-7 of guanine, disrupts DNA function due to cross linking, abnormal base pairing and DNA strand breakage, form cytotoxic free radicals, inhibits DNA replication and transcription
- Adverse Effects: bone marrow sparing, peripheral neuropathy, renal insufficiency, N/V
- Indications: bladder, lung, ovarian, and testicular cancers
Cell Cycle Non-Specific Agents: cyclophosphamide
- Class: alkylation Agents (nitrogen mustard)
Prototype: cyclophosphamide
- Mechanisms of Action: covalently binds to DNA at N-7 of guanine, DNA functions disrupted due to cross linking, abnormal base pairing and DNA strand breakage, activated via cytochrome P-450
- Adverse Effects:forms a role in, bladder toxicity
- Indications: breast and ovarian cancer, non-Hodgkin’s lymphoma
Cell Cycle Non-Specific Agents: Carmustine
- Class:Alkylation agent (nonclassical), nitrosourea
- Prototype: carmustine
- Mechanism of Action: highly lipid soluble, base catalyze decomposition generates the alkylating entity
- Adverse Effects: leukopenia, pulmonary fibrosis, N/V
- Indications: glioblastoma, lymphoma
Cell Cycle Non-Specific Agents: procarbazine
- Class: alkylating agents (nonclassical)
- Prototype: procarbazine
- Mechanism of Action: needs activation by cytochrome P-450, effects similar to alkylating agents
- Adverse Effects: leukemia, bone marrow suppression, N/V
- Indications: Hodgkin’s lymphoma, glioma
Cell Cycle Non-Specific Agents: doxorubicin
- Class: anthracyline inhibitors
- Prototype: doxorubicin
- Mechanism of Action: inhibits topoisomerase II, intercalated with DNA, forms free radicals
- Adverse Effects: myelosuppression, cardiotoxicity is dose limiting
- Indications: breast, lung, endometrial, and ovarian cancers, Hodgkin’s Lymphoma
Cell Cycle Non-Specific Agents: Daunorubicin
- Class: anthracycline antibiotics
- Prototype: daunorubicin
- Mechanism of Action: inhibits topoisomerase II, intercalated with DNA, forms free radicals
- Adverse Effects: myelosuppression, cardiotoxicity is dose limiting
- Indications: leukemias
Cell Cycle Non-Specific Agents: dactinomycin
- Class: other antibiotics
- Prototype: dactinomycin
- Mechanism of Action: inhibits DNA-dependent RNA synthesis
- Adverse Effects: bone marrow suppression
- Indications: choriocarcinoma, Wilm’s tumor, rhabdomyosarcoma, testicular cancer, Ewing sarcoma
Cell Cycle Non-Specific Agents: mitomycin
- Class: other antibiotics
- Prototype: mitomycin
- Mechanism of Action: biotransformed to an alkylating agent
- Adverse Effects: bone marrow suppression
- Indications: colon, superficial bladder, stomach, and pancreatic cancer
Cell Cycle Non-Specific Agents: rituximab
- Class: misc. antineoplastic agents
- Prototype: rituximab (monoclonal antibodies)
- Mechanism of Action: interacts with CD20 of normal and malignant B cells
- Adverse Effects: myelosuppression, hypersensitivity
- Indications: non-Hodgkin’s lymphoma
Cell Cycle Non-Specific Agents: imatinib
- Class: misc. antineoplastic agents
- Prototype: imatinib
- Mechanism of Action: inhibits abnormal tyrosine kinase created by Philly chromosome in CML
- Adverse Effects: diarrhea, nausea, cramps, fatigue
- Indications:
Cell Cycle Non-Specific Agents:
- Class:
- Prototype:
- Mechanism of Action:
- Adverse Effects:
- Indications:
Drug Resistance
- Increased DNA repair: alkylating agents
- Decreased activation of pro-drug: 5-fluorouracil, 6-mercaptopurine
- Formation of trapping agents: alkylating agents
- Decreased drug accumulation via increase in transporters: alkylating agents, dactinomycin, methotrexate
- Changes in target enzymes or receptors: vinca alkaloids, methotrexate, etoposide, gonadal hormones
- Formation of drug-inactivating enzymes: pyrimidine and purine analogs
Hodgkin’s Drug Regimen
ABVD-
Adriamycin (doxorubicin)
Bleomycin
Vinblastine
Dacarbazine (alkylating agent)
Toxicity: alopecia, GI distress, neutropenia, pulmonary fibrosis (bleomycin), delayed cardiomyopathy (doxorubicin)
Ames Test
Tests carcinogenic potential
Grow Salmonella in His lacking medium and have rat liver extract
Colonies only grow if get frameshift or substitution mutations, compare to Control with no added potential mutagen
Very sensitive
Dominant Lethal Test
Detects dominant lethal mutations
Expose male mice to mutagenic treatment and look at number of viable offspring
Dominant lethal mutations often from major chromosomal abnormalities
4 Phases of Drug Development
- Small group with normal healthy people, look at safety and pharmacokinetics
- Small group with target disease, figure out optimal dose regimen
- Multicenter trials, where drug gets approved
- Postmarketing surveillance, don’t need
Factors Influencing the Effectiveness of Placebo
- Color: multicolored is better
- Size: very small or large is better
- Route of administration: injection is better
- Physician’s attitude
- Cost: better if cost more
Code of Federal Regulations- Key Parts of Title 21
21 CFR 50: protection of human subjects, involves full consent
21 CFR 54: financial disclosure by investigators
21 CFR 56: IRB
21 CFR 312: responsibility of sponsors and investigators (form 1572)