L21, L23, L25- Chemotherapy and Neoplastic Diseases Flashcards
in general chemotherapies aim to attack (1) or (2)
- DNA
- metabolic sites essential to cell replication
- (1) chemotherapy is used to attack micrometastases following surgery and radiation
- (2) chemotherapy is given prior to surgery to shrink the cancer
- (3) chemotherapy is indicated when neoplasms are disseminated (spread) and surgery is not possible
1- Adjuvant
2- Neoadjuvant
3- Primary
destruction of cancer cells by drugs follows (1) kinetics, and is this phenomenon is termed (2)
1- first order (a given dose destroys a constant fraction of cells)
2- log kill
Diagnosis of leukemia requires (1) leukemic cells present. (2) log kills by treatment eliminates 99.999% of cancer cells to induce clinical remission. However, in the case of leukemia, (3) cells would remain, therefore (4) is required. In contrast, drugs for bacterial infections only require (5) log kills, as the body readily eliminates residual bacterial cells- not the case for cancer cells.
1- 10^9 2- 5 log kills 3- 10^4 cells (0.001%) 4- additional Tx (tumor cells aren't as readily eliminated as bacterial cells) 5- 3 log kills
describe the effects of combination chemotherapy
- multiple chemotherapy drugs used, each with different mechanism of action (standard approach)
- synergism can be reached
- used to prevent/slow down development of resistance to anticancer drugs
- maximal kill, tolerated toxicity: each drug has its own log kill and can destroy tumor cells that are resistant to the other drugs
- given intermittently to allow normal tissue to recover (ex. immune system to reduce chance of serious infection)
anticancer drugs are more effective on (rapid/slow) growing neoplasms, especially those with (large/small) growth fractions
1- rapid growth
2- large growth fraction (more cells in cell cycle)
list the two types of chemotherapy drugs and their subtypes
Cell Cycle-Specific agents: antimetabolites (S), bleomycin (G2), microtubule inhibitors (M), epipodophyllotoxins (S-G2), camptothecins (S-G2)
Cell Cycle-Nonspecific agents: alkylating agents, platinum coordination complexes, antitumor antibiotics
Cell cycle-specific drugs are most effective on (1) malignancies and other tumors with (2) as they target (3).
Cell cycle-nonspecific drugs are most useful for (4) tumors, as well as other tumors with (5) as they target (6).
1- hematologic
2- large growth fraction
3- cell cycle (S to M phases)
4- solid
5- large growth fraction
6- cells in Go phase or in cell cycle
primary drug resistance is defined as….
no response to a drug upon first exposure (naturally resistant)
acquired drug resistance can be either (1) due to (2) OR (3) because (4) occurs
1- single drug resistance
2- inc expression/amplification of one or more genes
3- multi-drug resistance (MDR)
4- resistance to several drugs after exposure to single agent (very difficult to Tx)
MDR mainly occurs as a result of…..
(multi-drug resistance)
- overexpression of membrane efflux pumps
- MOST importantly P-Glycoprotein (most responsible)
(T/F) chemotherapy drugs have a narrower therapeutic window compared to other drugs
T- usually higher dose needed for min therapeutic effects and lower dose needed for min toxic effects
chemotherapy drugs that target rapidly proliferating cells will also affect the following types of normal cells, (1), causing the following adverse effects, (2)
1- buccal mucosa, GI mucosa, bone marrow, hair cells
2- severe vomiting (GI), stomatitis (buccal- mouth/lip inflammation), bone marrow suppression, alopecia (hair)
the following drugs have high myelosuppression….
- cytarabine
- alkylating agents
- doxorubicin
- daunorubicin
- vinblastine
the following drugs have medium myelosuppression….
- carboplatin
- methotrexate (MTX)
- 5-FU (fluorouracil)
the following drugs have low myelosuppression….
- bleomycin
- vincristine
- asparaginase
Name the drug related to the following specific adverse effect:
(1) cardiotoxicity
(2) hemorrhagic cystitis
(3) peripheral neuropathy
(4) pulmonary fibrosis
1- doxorubicin
2- cyclophosphamide
3- vincristine, paclitaxel
4- bleomycin
_______ drugs are used to manage chemotherapy induced emesis (vomiting)
- 5-HT3 (serotonin) receptor blockers
- NK-1 (neurokinin) inhibitors
_______ drugs are used to prevent and treat chemotherapy induced neutropenia (from myelosuppression)
- filgrastim
- sargramostim
_______ drugs rescue bone marrow from MTX
leucovorin
(1) binds the metabolite of (2) drug- (3) - to prevent hemorrhagic cystitis
1- mesna
2- cyclophosphamide
3- acroleine
(1) drugs reduce anthracycline induced cardiotoxicity, usually from (2) drugs
1- dexrazoxane
2- doxorubicin
_______ drugs reduce renal toxicity of cisplatin
amifostine
because most antineoplastic agents are (1), (2) may arise 10 or more years after curing cancer; this is the biggest problem after therapy with (3)
1- mutagenic
2- neoplasms
3- alkylating agents
Antimetabolite chemotherapy drugs mostly target (1) related pathways, they are cycle-(non-/specific) affecting the (3) phase most. The three types of antimetabolites include: (4).
1- nucleotide or nuclei acid synthesis
2- cycle-specific
3- S phase (DNA replication)
4- folate analogs, purine analogs, pyrimidine analogs
The main folate analog of the antimetabolite drugs is (1), which functions to inhibit (2). This deprives the cell of folate and therefore decreases the synthesis of (3) specifically and (4) overall.
1- MTX (methotrexate)
2- dihydrofolate reductase
3- dTMP (from dUMP) and purine synthesis
4- DNA, RNA, proteins => cell death
describe the mechanism of action of MTX in detail
- inhibits dihydrofolate reductase
- catalyzes folate –> DHF and DHF –> THF
- THF (tetrahydrofolate) is methylates to Me-THF
- Me-THF is needed for thymidylate synthase to convert dUMP –> dTMP AND for adenine/guanine synthesis
- => incomplete and disrupted DNA(/RNA) synthesis
MTX metabolism is defined as the conversion to (1) by (2) enzyme
1- polyglutamates (MTX-PGs)
2- folylpolyglutamate synthase (FPGS)
list the adverse effects on MTX
- Common: stomatitis, mucositis, myelosuppression (medium), alopecia, nausea/vomiting
- Uncommon is renal damage if high dose is given
- hepatic fibrosis, cirrhosis
- pneumonitis
- neurological toxicities with IT administration (intrathecal, administration into CSF for brain tumors as MTX won’t cross BBB)
Leucovorin is also called (1), and is an antidote to (2) drugs in order to rescue (3) as it provides normal tissue with (4).
1- N(5)-formyl-THF (replaces Me-THF)
2- folate analogs / MTX / drugs that reduce folate
3- bone marrow
4- reduced folate (bypassing DHFR inhibition by MTX)
[basically used so normal cells (bone marrow) can produce dTMP, purines (adenine/guanine) for DNA/RNA synthesis during chemotherapy, although too much would cancel the effects of MTX]
list the two main purine analogs
- 6-MP (6-mercaptopurine)
- 6-TG (6-thioguanine)
6-MP is an analog of (1), and is converted to (2) by (3) enzyme. (2) will inhibit (4) and block the formation of (5). Lastly, dysfunctional (6) will result from incorporated (7) analogs.
(6-mercaptopurine) 1- (thiol analog of) hypoxanthine 2- thiol-IMP 3- HGPRT (salvage pathway) 4- 1st step of de novo purine ring biosynthesis 5- AMP/GMP from IMP 6- DNA, RNA 7- guanylate analogs
6-MP is metabolized into (1) by (2) enzyme. 6-MP should not be given to patients taking (3) drug as it inhibits (2).
(6-mercaptopurine)
1- thiouric acid
2- xanthine oxidase
3- allopurinol (–> oxypurinol by xanthine oxidase is the effector)
list the adverse effects of 6-MP
(6-mercaptopurine)
- n/v/d
- myelosuppression
- hepatotoxicity
list the cell cycle-specific agents and the associated phases they affect
- antimetabolites (S phase)
- bleomycin (G2 phase)
- MT inhibitors (M phase)
- epipodophyllotoxins (S-G2 phase)
- camptothecins (S-G2 phase)
list the cell cycle-nonspecific agents
alkylating agents, platinum coordination complexes, antitumor antibiotics (except bleomycin)
P-glycoprotein can lead to MDR to the following anticancer drugs: (1)
They cannot transfer the following cancer drugs: (2)
1- doxorubicin, daunorubicin, dactinomycin, vincristine, vinblastine, etoposide
2- alkylating agents, antimetabolites, cisplatin
what are the contraindications of using MTX
MTX is teratogenic and abortifacient – avoid in pregnancy
6-MP is mostly used in (1) cancer.
It has resistance based on the following: (2), (3), (4)
(6-mercaptopurine)
1- acute lymphatic leukemia
2- HGPRT deficiency / Lesch-Nyhan syndrome: cannot bio-transform 6-MP
- inc dephosphorylation
- inc metabolism of drug to thiouric acid
After administration of 6-thioguanine, it is converted to (1) in order to (2) and (3). It is mainly used for (4) cancers. Its toxic adverse effects include: (5).
1- nucleotide / TGMP
2- inhibit purine synthesis / phosphorylation of GMP –> GDP
3- incorporate into DNA, RNA –> dysfunctional strands
4- acute nonlymphocytic leukemias
5- -n/v/d, myelosuppression, hepatotoxicity
6-MP and 6-TG are secondarily metabolized by….
TPMT- thiopurine methyltransferase: if it has weak activity then they cause inc risk of severe toxicities (myelosuppression)
list the pyrimidine analogs
- 5-FU (5-fluorouracil)
- capecitabine
- cytarabine
5-FU is converted to (1) in order to inhibit (2) and therefore (3). (4) will result as a consequence. 5-FU can also be converted to (5) to disrupt (6).
(5-fluorouracil) 1- 5-FdUMP 2- thymidylate synthase (dec dTMP) 3- DNA synthesis 4- thymineless cell death 5- 5-FUTP 6- RNA processing and function due to incorporation
5-FU is metabolized by (1) enzyme, which is deficient in (2)% of cancer patients who will suffer with (3)
(5-fluorouracil)
1- DPD (dihydropyrimidine dehydrogenase)
2- 5% Pts
3- severe toxicity: myelosuppression, neurotoxicity, life-threatening diarrhea
traditional adverse effects of 5-FU are…
(5-fluorouracil)
- n/v, alopecia, myelosuppression
- erythematous desquamation of hands/soles (‘hand-foot’ syndrome) after extended infusions
5-FU is commonly combined with (1) in (2) cancer. A (3) complex formation results, since (1) increases the levels of (4). In essence (1) potentiates the activity of 5-FU.
(5-fluorouracil) 1- leucovorin (N5-formyl-THF) 2- colorectal cancer 3- thymidylate synthase-5F-dUMP-N5,N10-methylene-THF complex 4- N5,N10-methylene-THF