Intro to Cancer Pharmacology Flashcards
1
Q
Cell Cycle
A
- G1: DNA is 2n
- S-phase: DNA replication, synthesizing two identical replicas of DNA (2n => 4n)
- G2: DNA is 4n
- Mitosis: splitting to two single cells (4n => 2n)
2
Q
Cell-Cycle Specific (CCS) Agents
A
- Inhibit or kill during a particular phase of cell cycle
- Schedule dependent - need to maintain a cytotoxic level for enough time to allow a tumor to cycle through
- More effective against tumors with high growth fractions
3
Q
Antimetabolites Agents + Phase
A
- All S phase
- Folic acid analogs
- Purine analogs (and related antagonists)
- Pyrimidine analogs
4
Q
Antimetabolites Agent Info
A
- Widely Used
- MoA: structural analog and antagonists of endogenous biochemicals that inhibit purine/pyrimidine synthesis
- Transported/metabolized/used in biochemical pathways similar to their analogous biochemical
- Cell-cycle specific with cytotoxicity present in S-phase (phase with nucleotide production)
5
Q
Antifolates
A
- Structural analog of folic acid
- Folic acid’s active form = tetrahydrofolic acid (TFA)
- TFA involved in single carbon unit transfers as methyl and in purine/pyrimidine metabolism
- MoA: inhibits dihydrofolate reductase and antifolate activity, also inhibits 1 carbon transfers associated with certain AA
6
Q
Antifolate Examples
A
- Methotrexate
- Trimetrexate
- Aminopterin
- Pemetrexed
- Pralatexate
7
Q
Methotrexate Absorption Differences
A
- Low dose methotrexate enters cells through folate transporters
- High dose methotrexate enters by passive uptake and folate transporters
8
Q
Leucovorin Rescue
A
- Reduced folate derivative used to replenish folate pools in normal cells
- Enters cells with intact folate transporters
- Bypasses methotrexate blocked enzyme to replenish folate pool
- Normal cells only have reduced folate, tumors remain folate starved
- Made use of 5-FU more efficacious, binds TS more avidly when coadministered
9
Q
Purine Analogs
A
-MoA: inhibition of enzymes involved in de novo purine nucleotide synthesis
EXAMPLES
- 6-mercaptopurine (6MP)
- 6-thioguanine (6TG)
- Fludarabine monophosphate
- Cladribine
10
Q
6MP and 6TG
A
- Require bioactivation by HGPRT to ultimately form triphosphate metabolite
- Incorporated into DNA and RNA
- Inhibit biosynthesis of endogenous purines by inhibiting PRPP amidotransferase
- Decrease DNA/RNA synthesis
- Active in S phase
- Short half life due to excesive metabolism
- Used in leukmekias (and IBD)
11
Q
Fludarabine Monophosphate-
A
- Fludara
- Requires phosphorylation to be active
- Inhibits DNA polymerase causing DNA chain termination
- Incorporated into RNA
12
Q
Cladribine
A
- Leustatin
- Requires phosphorylation to be active
- Inhibits DNA synthesis and repair
13
Q
Pyrimidine Analogs
A
- MoA: inhibits synthesis pyrimidine nucleotides mimicking their structure to inhibit DNA synthesis of RNA synthesis
- Analogs of thymidine and cytidine and analogs of uracil (latter RNA/DNA synthesis)
14
Q
Pyrimidine Analog Examples
A
- 5-FU
- Capecitabine
- Cytarabine
- Gemcitabine
- Trifluridine and tipiracil (TAS-102)
All are thymidine/cytidine analogs that block DNA synthesis
15
Q
5-FU
A
- Requires GPAT and orotate phosphribosyl transferase activity to form FdUMP from 5-FU
- MoA: F-dUMP binds to thymidine synthase and methylene-tetrahydrofolate to inhibit thymidylate synthase activity and block thymidine production
- Causes thymidine starvation and inhibition of DNA synthesis
- 5-FU is also bioactivated to 5-FUTP and incorporated into RNA to interfere with RNA processing
- 5-FU has a short half life due to extensive metabolism
- Used in colorectal cancer and solid tumors
16
Q
Capecitabine
A
- Xeloda
- Prodrug requiring carboxylesterase, cytidine deaminase, and thymidine phosphorylase activity to produce active form, 5-FU
- Hydrolysis to 5-FU by thymidine phosphorylase, present at higher levels in some tumors and leads to concentration in tumors
- Orally bioavailable by metabolism activity
- Cytotoxicity similar to 5-FU
17
Q
Trifluridine and Tipiracil
A
- TAS-102 (Lonsurf)
- Fluoropyrimidine analog
- Made up of trifluridine (fluorinated pyrimidine analog) and tipiracil (inhibitor of thymidine phosphorylase)
- Trifluridine is inactive in its parent form, inhibits thymidylate synthase
- Approved for colorectal cancer as second line therapy due to toxicities
- Dose-limiting toxicity: neutropenia dominant myelosuppression, diarrhea, N/V, fatigue, anorexia
18
Q
Cytarabine
A
- ara-C
- S-phase specific
- Uses arabinose sugar
- Bioactivation to araCMP by deoxycytidine kinase to araCTP
- Inhibits DNA polymerase alpha/beta to block DNA synthesis and repair
- Short half life due to extensive metabolism
- Not effective orally, metabolized to ara-uridine in liver
- Used in hematologic malignancies, acute myelogenous leukemia, and non-Hodgkin’s lymphoma
- NO SOLID TUMOR ACTIVITY
- Toxicity: myelosuppression, mucositis, N/V
19
Q
Gemcitabine
A
- Structure and mechanism similar to ara-C
- Rapidly eliminated from the plasma
- Greater cellular accumulation
- Use: broader than ara-C, can be used in solid tumors
20
Q
Antimetabolites DLT
A
- Methotrexate: myelosuppression and mucositis (oral/intestinal ulcerations)
- 6MP: myelosuppression, mucositis, gastrointestinal distress, hepatotoxicity
- 5-FU: myelosuppression, mucositis, GI distress, hand-foot syndrome, neurotoxicity
21
Q
Hydroxyurea
A
- Inhibits ribonucleotide reductase
- Used in treatment of polycythemia vera (myeloproliferative neoplasm), CML, and myeloid metaplasia
- Debatable antimetabolite
22
Q
Antimitotic Agents + Phases
A
- All M-phase
- Taxanes
- Vinca alkaloids
- Antimicrotubule inhibitors
23
Q
Antimitotic Agents + Microtubules
A
- Active on microtubules and associated cellular structures
- Microtubules maintain cell shape, localize organelles, and are used for transport, secretion, and mitosis
- Active in M phase due to microtubule importance in formation of mitotic spindle in mitosis