Cancer Pharmacology Flashcards
Categories of alkylating agents used in chemotherapy
Bis (chloroethyl) amines, nitrosoureas, aziridines, alkylsulfonate, non-classic alkylating agents, platinum analogs
Of the alkylating agents, name the 4 bis (chloroethyl) amines
Cyclophosphamide
Mechlorethamine
Melphalan
Chlorambucil
Of the alkylating agents, name the 2 nitrosureas
Carmustine
Streptozocin
Of the alkylating agents, what is the major aziridine used in chemotherapy?
Thiotepa
Of the alkylating agents, what is the major alkylsulfonate used in chemotherapy?
Busulfan
3 non-classic alkylating agents
Procarbazine
Dacarbazine
Bendamustine
Of the alkylating agents, name the 3 platinum analogs
Cisplatin
Carboplatin
Oxaliplatin
4 categories of antimetabolites used in chemotherapy
Antifolates
Fluoropyrimidines
Deoxycytidine analogs
Purine antagonists
Of the antimetabolites, what are the 3 antifolates used in chemotherapy?
Methotrexate
Premetrexed
Pralatrexate
Of the antimetabolites, what are the 3 fluoropyrimidines used in chemotherapy?
5-FU
Capecitabine
TAS-102
Of the antimetabolites, what are the 2 deoxycytidine analogs used in chemotherapy?
Cytarabine
Gemcitabine
Of the antimetabolites, what are the 4 purine antagonists used in chemotherapy?
6-thiopurines:
6-mercaptopurine (6-MP)
6-thioguanine (6-TG)
Other:
Fludarabine
Cladribine
Categories of chemotherapy drugs considered natural products
Vinca alkaloids
Taxanes and other anti-microtubule drugs
Epipodophyllotoxins
Camptothecins
Of the natural products used in chemotherapy, name the 3 vinca alkaloids
Vinblastine
Vincristine
Vinorelbine
Of the natural products used in chemotherapy, name the 5 taxanes and other antimicrotubule drugs
Paclitaxel Docetaxel Cabazitaxel Ixabepilone Eribulin
Of the natural products used in chemotherapy, name the epipodophyllotoxin
Etoposide
Of the natural products used in chemotherapy, name the camptothecins
Topotecan
Irinotecan
Name the anti-tumor antibiotics
Anthracyclines: doxorubicin, daunorubicin, idarubicin, epirubicin, mitoxantrone, derazoxane
Mitomycin (myotmycin C)
Bleomycin
5 tyrosine kinase inhibitors used in chemotherapy
Imatinib Dasatinib Nilotinib Bosutinib Ponatinib
Growth factor receptor inhibitors used in chemotherapy
Cetuximab Panitumumab Necitumumab Erlotinib Afatinib Osimertinib Bevacizumab Ziv-aflibercept Ramucirumab Sorafenib Sunitinib Pazopanib
Most widely used alkylating agent with high oral bioavailability, administered by IV or orally, and activated to the 4-hydroxy intermediate
Cyclophosphagmide
Cyclophosphamide is activated to become 4-hydroxycyclophosphamide, which travels alongside aldophosphamide in circulation. What is the fate of these molecules in liver and tumor tissue?
4-hydroxycyclophosphamide is inactivated in liver or tumor tissue (inactive metabolites include 4-ketocyclophosphamide and carboxyphosphamide)
Aldophosphamide cleaves spontaneously in tumor tissue generating the toxic metabolites (toxic metabolites include phosphoramide mustard and acrolein)
AEs of cyclophosphamide
Phosphoramide mustard responsible for antitumor effects
Acrolein causes hemorrhagic cystitis
Patients should receive vigorous IV hydration during high-dose treatment
Cyclophosphamide has broad clinical applications. What are some of them?
Essential component of many effective drug combinations for: NHL, other lymphoid malignancies, breast and ovarian cancers, solid tumors in children
Burkitt lymphoma — complete remissions and presumed cures when given as a single agent
Used in combo with doxorubicin an da taxane as adjuvant therapy after surgery for breast cancer
First clinically used nitrogen mustard
Most reactive of drugs in its class
Clinical application include topical use for tx of cutaneous T cell lymphoma (CTCL)
Largely replaced by more stable chemotherapeutics
Mechlorethamine
Melphalan is not a vesicant and has inconsistent absorption orally so it is given by IV. What are adverse effects of melphalan?
Toxicity is mostly hematologic
NOTE: N/V and alopecia are less frequent vs. other chemotherapeutics
Clinical application of melphalan
Primarily used to treat multiple myeloma with dexamethasone
Oral chemotherapeutic that is administered orally, considered to have adequate and reliable absorption
It is usually well tolerated in small daily doses, although N/V can occur in a single daily dose >20mg
Clinically used to tx chronic lymphoblastic leukemia (CLL)
Chlorambucil
Describe nitrosureas as a class in terms of cross resistance with other alkylating agents, lipid solubility and related clinical implications, and chemical moieties generated
Not cross resistant with other alkylating agents
Lipid soluble — can cross the blood brain barrier making them effective at treating brain tumors
Generate both alkylating and carbamylating moieties
Major action and lipid solubility of carmustine
Major action is its alkylation of DNA — this can be repaired by MGMT
Highly lipophilic — crosses BBB
AEs of carmustine
Profound and delayed myelosuppression — recovery 4-6 weeks after a single dose
In high doses with bone marrow rescue, carmustine produces hepatic VOD, pulmonary fibrosis, renal failure, and secondary leukemia
Clinical applications of carmustine
Malignant gliomas (implantable carmustine wafer); [Methylation of the MGMT promoter inhibits its expression of 30% of primary gliomas]
Associated with sensitivity to carmustine and other nitrosoureas
Chemotherapeutic with high affinity for cells of islets of Langerhans, causing diabetes in experimental animals
Used clinically to tx human pancreatic islet cell carcinoma and carcinoid tumors
Streptozocin
AEs of streptozocin
Frequent nausea
Mild reversible renal or hepatic toxicity occurring in approx 2/3 of cases (10% will have cumulative dose renal toxicity that can lead to renal failure)
Aziridine chemotherapeutic that is rapidly converted by hepatic CYPs to its desulfurated primary metabolite; used for high-dose chemotherapy regimens in transplants for hematological malignancies
Thiotepa (primary metabolite = TEPA)
[both thiotepa and TEPA from DNA cross links]
AEs of thiotepa
Little toxicity other than myelosuppression
AEs at high doses include mucosal and CNS toxicity, coma and seizures
Orally administered alkylsulfonate chemotherapeutic used to treat chronic myeloid leukemia
Busulfan
AEs of busulfan
At the standard dose — causes myelosuppression
At high doses — causes pulmonary fibrosis, GI mucosal damage, and hepatic VOD (veno-occlusive disease)
When a pt is receiving chemotherapy with busulfan, what drugs are given concomitantly and why?
Anti-convulsants — to protect against acute CNS toxicities
Phenytoin — increases GSTs that metabolize busulfan; reduces AUC by 20%
Non-enzyme inducing benzodiazepines recommended (lorazepam and clonazepam)
Non-classic alkylating agent with incompletely understood MOA; converted by CYP mediated oxidative metabolism to highly reactive alkylating species that methylate DNA; can produce chromosomal damage including chromatid breaks and translocations consistent with its mutagenic and carcinogenic actions, inhibits DNA, RNA, and protein biosynthesis, prolongs interphase (cell cycle), produces chromosome breaks
Procarbazine
Resistance to procarbazine develops rapidly when its used as a single agent (i.e., increased expression of MGMT). What are other AEs of procarbazine?
Carcinogenic potential higher than that of other alkylating agents
Increased risk of secondary cancers — acute leukemia
Augments sedative effects — concomitant CNS suppressants should be avoided
Disulfuram-like actions — avoid alcohol
Clinical applications of procarbazine
Used in the MOPP regimen for Hodgin disease
Also used in treating gliomas as a part of the PVC regimen (procarbazine + vincristine + lomustine [CCNU])
The prodrug of ______ functions as a methylating agent after being converted to monomethyl triazeno metabolite MTIC
Resistance develops due to __________
It is administered parenterally
Dacarbazine
Removal of methyl groups by MGMT
AEs of dacarbazine
Myelosuppression
N/V (90% of pts) — vomiting develops 1-3 hours after treatment and may last up to 12 hours; can be severe
Flu-like syndrome may occur
Clinical application of dacarbazine
Primary indication = Hodgkin disease
Modestly effective against malignant melanoma and adult sarcomas
MOA of bendamustine
Forms cross-links with DNA resulting in single and double stranded breaks —> inhibition of DNA synthesis and function
Inhibits mitotic check points and induces mitotic catastrophe —> cell death
Bendamustine’s cross resistance with other alkylating agents is only partial. What are adverse effects of Bendamustine?
Myelosuppression (rapidly reversible)
Mucositis (rapidly reversible)
Mild nausea and vomiting
Clinical applications of bendamustine
Approved for tx of CLL (chronic lymphoblastic leukemia) and non-Hodgkin lymphoma
MOA of the alkylating agents that are platinum analogs
[precise MOA unknown]
Kills tumor cells in all stages of the cell cycle
Binds DNA through formation of intra- and inter-strand cross links
Inhibits DNA synthesis and function
Platinum analog alkylating agents exhibit synergism with other alkylating agents, ______, and ______
Fluoropyrimidines; taxanes
Platinum analog only given by IV, requiring preceding tx with chloride diuresis via 1-2L NS to prevent renal toxicity, as well as vigorous IV hydration
Cisplatin
_____ inactivates cisplatin, thus the drug should not come into contact with needles or other infusion equiment containing it
Aluminum
T/F: cisplatin has abundant CNS penetration
False — it is found in highest concentrations in kidney, liver, intestine, and testes
It has poor CNS penetration
AEs of cisplatin
Nephrotoxicity [diminished by pretreatment with hydration and chloride diuresis]
Ototoxicity — manifests as tinnitus and leads to high frequency hearing loss
N/V occur in almost all pts
High doses/multiple tx may lead to progressive peripheral motor and sensory neuropathy (may worsen after discontinuation)
Mild to moderate disturbances in electrolytes — tubular damage may lead to renal electrolyte wasting and may produce tetany if untreated
Anaphylactic rxns may occur w/i minutes after administration (facial edema, bronchoconstriction, tachycardia, hypotension)
Treatment with cisplatin can lead to the development of what hematologic malignancy, usually 4+ years after treatment?
AML
How is the common adverse effect of N/V managed during cisplatin tx, as well as tx with other chemotherapy drugs?
5-HT3 receptor antagonists
NK1 receptor antagonists
High dose corticosteroids
Clinical applications for cisplatin therapy
Cisplatin in combo with bleomycin or etoposide (and with added vinblastine) cures 90% of pts with testicular cancer
Cisplatin used with paclitaxel induces complete response in majority of pts with ovarian carcinoma
Other cancers that respond to cisplatin: bladder, head and neck, cervix, endometrium, lung, rectal, anal, childhood neoplasms
______ has a similar MOA, resistance, and spectrum of activity as cisplatin but is a very different chemically, pharmacokinetically, and in terms of toxic properties. It is given IV and does NOT require vigorous IV hydration like cisplatin does
Carboplatin
AEs of carboplatin
Well tolerated clinically with less nausea, neurotoxicity, ototoxicity and nephrotoxicity than cisplatin
Dose limiting toxicity is myelosuppression —> thrombocytopenia
Hypersensitivity reaction — managed by administering graded doses of the drug and more prolonged infusions which lead to desensitization
Clinical applications of carboplatin
Carboplatin and cisplatin are equally effective in the tx of debulked ovarian cancer, non-small cell lung cancer, extensive-stage small cell lung cancer
Used with paclitaxel to induce complete response in majority of ovarian carcinoma
In terms of germ cell, head and neck, and esophageal cancers — which is more effective: carboplatin or cisplatin?
Cisplatin
Carboplatin can be an effective alternative to cisplatin in pts with what conditions?
Impaired renal function
Refractory nausea
Significant hearing impairment
Neuropathy
Oxaliplatin has the same mechanism as the other platinum analogs. What are some adverse effects of oxaliplatin?
Peripheral sensory neuropathy (acute form vs. cumulative dose)
Nausea is well controlled with 5-HT3 receptor antagonists
May cause leukemia and pulmonary fibrosis months to years after administration
May elicit an allergic response — urticaria, hypotension, and bronchoconstriction
Describe acute vs. cumulative dose forms of peripheral sensory neuropathy caused by oxaliplatin
Acute form: often triggered by exposure to cold liquids; paresthesias or dysesthesias in the upper and lower extremities, mouth, and throat
Cumulative dose: similar to cisplatin neuropathy; progressive sensory neurotoxicity — dysesthesias, ataxia, numbness of extremities
Clinical applications of oxaliplatin
Colorectal and gastric cancer
Oxaliplatin suppresses expression of _____ _____, which may be the rationale for the synergy with 5-FU. Oxaliplatin is approved in combination with 5-FU for _________ cancer
Thymidylate synthase (TS); colorectal
MOA of methotrexate
Folic acid analog that binds to the active site of dihydrofolate reductase
Inhibits synthesis of tetrahydrofolate (THF) [the one-carbon carrier for de novo synthesis of thymidylate, purine nucleotides, and amino acids serine and methionine]
Interference in formation of DNA, RNA, and key cell proteins
[Folyl polyglutamate synthase (FPGS) catalyzes formation of intracellular polyglutamate metabolites which are selectively retained in cancer cells]
4 Resistance mechanisms to methotrexate
Decreased drug transport via reduced folate carrier or folate receptor protein
Decreased formation of cytotoxic methotrexate polyglutamates
Increased levels of target enzyme DHFR through gene amplification and other genetic mechanisms
Altered DHFR protein with reduced affinity for methotrexate
Methotrexate may be administered IV, intrathecal, or orally. What 4 drugs inhibit the renal excretion of methotrexate, thus leading to increased risk of methotrexate toxicity?
Aspirin
NSAIDs
Penicillin
Cephalosporins
Methotrexate action can be reversed by administration of reduced folate ________, a drug sometimes used in conjunction with high dose methotrexate therapy to rescue normal cells from undue toxicity
Leucovorin
Clinical applications of methotrexate
Breast cancer
Head and neck cancer
Osteogenic sarcoma
Primary CNS lymphoma
Non-Hodgkins lymphoma
Bladder cancer
Choriocarcinoma
Antimetabolite chemotherapeutic active in the S-phase and transported into the cell via reduced folate carrier and requires activation by FPGS to yield higher polyglutamate forms (like methotrexate)
Pemetrexed
MOA of pemetrexed
Inhibition of thymidylate synthase (TS)
Targets and inhibits DHFR and enzymes involved in de novo purine nucleotide biosynthesis
Adverse effects of pemetrexed
Myelosuppression, skin rash, mucositis, diarrhea, fatigue, and hand-foot syndrome (painful erythema and swelling — tx with dexamethasone)
Vitamin supplement with _____ and _____ significantly reduces toxicities associated with pemetrexed and pralatrexate
Folic acid and vitamin B12
Clinical applications of pemetrexed
Mesothelioma
Approved for use in combo with cisplatin for the first-line tx of NSCLC and as maintenance therapy in pts with NSCLC whose disease has not progressed after 4 cycles of platinum-based chemotherapy
Antimetabolite similar to methotrexate in that it is transported into the cell via reduced folate carrier (RFC) and requires activation by FPGS to yield higher polyglutamate forms, but designed to be more potent substrate for the RFC and FPGS
Pralatrexate
MOA of pralatrexate
Inhibits DHFR
Inhibits enzymes involved in de novo purine nucleotide biosynthesis
Inhibits thymidylate synthase
AEs of pralatrexate
Myelosuppression, skin rash, mucositis, diarrhea, fatigue
Clinical application for pralatrexate
Approved for tx of relapsed or refractory peripheral T-cell lymphoma
Active metabolites of 5-FU and their MOA
FdUMP — binds and forms a ternary complex with TS and reduced 5,10-methylenetetrahydrofolate; inhibition of DNA synthesis through “thymineless death”
FUTP — incorporated into RNA where it interferes with RNA processing and mRNA translation
FdUTP — incorporated into DNA resulting in inhibition of DNA synthesis and function
5-FU is administered IV and has an extremely _____ half life; it is catabolized by the enzyme ___________
Short (10-15 mins)
Dihydropyrimidine dehydrogenase (DPD)
[AR syndrome associated with partial or complete deficiency of the DPD gene seen in 5% of pts — leads to toxicities of myelosuppresion, GI toxicity with diarrhea/mucositis, and neurotoxicity]
AEs of 5-FU
Myelosuppression
GI toxicity (diarrhea/mucositis)
Skin toxicity (hand-foot syndrome)
Neurotoxicity
Clinical applications of 5-FU
Activity against a wide range of solid tumors — breast, stomach, pancreas, esophagus, liver (hepatocellular), head and neck, and anus
Most widely used drug in the tx of colorectal cancer (both as an adjuvant and for advanced disease)
5-FU
Prodrug metabolized to 5-FU in the cancer cell by thymidine phosphorylase, at which time MOA is the same as 5-FU
Capecitabine
The expression of thymidine phosphorylase is higher in what type of tumors (as opposed to normal tissue)?
Solid tumors (e.g., breast, colorectal cancer)