Dr. Chen Heme.Onc. Exam II Study Guide PDF

**PHRD736-- Traditional Chemotherapy** **REVIEW/STUDY GUIDE** 1. **What is carcinogenesis? What are the stages for carcinogenesis and when do the evidence of clinical disease start to show? SLIDE 6** Carcinogenesis: 3 stages, evidence of clinical disease usually shown in early progre...

**PHRD736-- Traditional Chemotherapy** **REVIEW/STUDY GUIDE** 1. **What is carcinogenesis? What are the stages for carcinogenesis and when do the evidence of clinical disease start to show? SLIDE 6** Carcinogenesis: 3 stages, evidence of clinical disease usually shown in early progression. 2. **What are the three major classes of anti-cancer drugs? What are the differences in MOA and side effects among the different classes of anti-cancer drugs? SLIDE 8** a. Traditional cytotoxic cancer therapy: Kill cancer cells by interfering with cellular replication including cell cycle specific agents (antimetabolites, microtubule inhibitors, kill cancer cells during specific phases of the cell cycle) and cell cycle non-specific agents (alkylating agents and antibiotics, kill cancer cells in any phase of the cell cycle). Traditional cytotoxic agents are more effective at killing cells undergoing cell division. Other cells that rapidly dividing such as cells in the GI tract and bone marrow will be susceptible to being killed. That is why many cytotoxic cancer therapeutic agents cause toxicities such as diarrhea, mucositis and myelosuppression. b. Targeted therapy includes monoclonal antibodies and kinase inhibitors. They are designed to recognize biomarkers that are present on cancer cells or other cells that are essential for cancer growth. Their side effects profiles are very different from traditional cytotoxic agents. c. Cancer immunotherapy includes checkpoint inhibitors (PD-1/PD-L1, CTLA-4) and CAR T-cell therapy. They can boost the immune system's ability to recognize and attack cancer. Side effects mainly are immune-mediated toxicities. 3. **Please explain the phases of cell cycle and the classification of anti-cancer drugs based on their activities in difference phases of cell cycle, indicating the general applications for different classes. SLIDE 12 - 14** d. Phases of cell cycle: G1 (Synthesis of cellular components (enzymes and proteins) needed for DNA synthesis), S (Replication of DNA genome), G2 (Synthesis of cellular components (RNA and proteins) for mitosis), M (cell division to two identical daughter cells). (***TEST QUESTION***) e. Two classes: Cell cycle specific drugs which are effective for high-growth-fraction malignancies such as hematologic cancers; and cell-cycle non-specific agents which are effective for both low-growth-fraction such as solid tumors as well as high-growth-fraction malignancies.(***TEST QUESTION***) 4. **What are the two main concerns of traditional chemotherapy? SLIDE 15 - 16** f. **Side effects**: on bone marrow cells, GI cells and hair follicles, and maybe carcinogenic themselves g. **Resistance**: several mechanisms related to enzyme modification, drug access and increased repair. 5. **What are the structural features of DNA alkylators and their general MOA? SLIDE 19** h. **Structures**: extremely reactive electrophilic i. **MOA**: attack guanine base (usually N7 or O6) and irreversibly (covalent bond) alkylate DNA base. i. **Nitrogen mustards**: Bis(β-haloalkyl)amines, form aziridine ion, attack N7 of guanine. ii. **Nitrosoureas**: unstable and decomposition to generate vinyl carbocation and chloroethyl carbocation to alkylate guanine. iii. **Procarbazines**: Metabolized to generate methyl radical that alkylate guanine mostly at O6. iv. **Triazines**: Metabolized (enzymatic or non-enzymatic) to methyl carbocation that alkylate guanine mostly at O6. v. **Organoplatinum complex**: hydroxylated to generate Pt^2+^ that attack guanine bases at N7. 6. **How can DNA Alkylating agents kill the cancer cells? Which phase(s) are these agents most active? SLIDE 20 & 22** j. Killing cancer cells by 3 ways i. DNA cross-linking prevents replication or transcription. ii. DNA alkylation creates mispairing (alkylated G paired with T instead of C) iii. DNA alkylation can recruit DNA repair enzymes which can break DNA strands. k. DNA alkylators are non-cell-cycle specific agents but are more toxic in late G1 and S phase when DNA is unwinding and exposing its bases. 7. **Familiar with the SAR for Nitrogen Mustards anti-cancer drugs and drugs in this class. SLIDE 23 - 33** a. **SAR**: i. **aliphatic** substitution at N → high reactivity, low selectivity, high toxicity, oral dose not possible. ii. **aromatic** substitution at N → low reactivity, high selectivity, low toxicity, oral dose possible. b. **Drugs**: iii. iv. v. vi. vii. viii. 8. **Familiar with nitrosoureas. SLIDE 36** a. Important drugs: i. **Carmustine** (highly lipophilic, IV dose with 10% ethanol), ii. **Lomustine** (oral use) iii. **Streptozocin**: natural product, water soluble, islet cell specificity 9. **Familiar with Procarbazine and Triazines SLIDE 37 & 38** l. **Procarbazine**: degradation generate methyl radical that can alkylate guanine at O6, C8 and N7; oral dose; inhibit MAO avoid drug/drug or drug/food interaction.). m. **Dacarbazine**: IV dose, P450 enzyme required in activation/metabolism, generate methyl carbocation that can methylate O6 and N7 of guanine. n. **Temozolomide**: oral dose, non-enzymatic activation, little P450 metabolism, generate methyl carbocation that can methylate N6 and N7 of guanine 10. **What is the MOA for Busulfan? Which positions in the structure of busulfan are nucleophilic to attack the base in DNA strands? SLIDE 39** o. **MOA**: CH2 groups next to sulfonate esters are nucleophilic to attack N7 of guanine in DNA strands, leading to DNA cross-linking. p. 4 CH2 between sulfonate esters -- intrastrand cross-linking; 1, 6 or 8 CH2 groups between sulfonate esters -- interstrand cross-linking. 11. **Familiar with the organoplatinum agents (General MOA: Cross-link DNA and interfere with DNA synthesis and cell replication) SLIDE 40 - 42** b. Because of platinum, they can cause a few toxicities that are similar to symptoms of heavy metal poisoning like peripheral sensory neuropathy, ototoxicity and nephrotoxicity. All react with aluminum and cannot be administrated through Al-containing needles. All are renally eliminated and require dose adjustments for renal impairment. c. Electron-deficient metal as a magnet for electron-rich DNA nucleophiles, bifunctional, most frequently intrastrand cross-linking of the DNA, square-planar geometry, hydrated platinum analogs are the active form that can alkylate DNA to form crosslinked DNA. d. Important drug: i. **Cisplatin** (hydroxylated active form, IV dose, highly nephrotoxic, photosensitive), ii. **Carboplatin** (less potent, for ovarian cancer, suppression of platelets and white blood cells) iii. **Oxaliplatin** (the 2^nd^ generation of organoplatinum agents which retains its activity in patients who are no longer responding to 1^st^ generation organoplatinum agents such as cisplatin.) e. **Sodium thiosulfate** inactivates **Cisplatin** to neutralize active cisplatin in the kidneys. 12. **Anticancer antibiotics (General MOA: intercalates with DNA, inhibits Topo II \[*except* Bleomycin\]) SLIDE 45 & 50 - 52** q. **Anthracyclines** and **anthracenediones**: i. **Structure:** Tetracyclic quinone-containing ring with aminoglycoside side chain ii. **MOAs** -- Intercalation of DNA (does not kill), then Top II inhibition (usually repairs DNA) generates radical, reactive oxygen species (ROS) DNA damage and breaks iii. **Side effects** - cardiotoxicity from cytotoxic free radicals which are important for anticancer activity, and chronic cardiotoxicity from metabolism at C13, CH2OH group at C13 is better than CH3 group), reddish-orange color "rubicin" maintained in the urine is not hemorrhagic. r. **Dactinomycin**: 2 pentapeptide lactones attached to an aromatic actinocin structure, intercalates DNA and inhibits topo II, binding to DNA is pseudoirreversible as binding of the 2 portions to DNA is cooperative which leads to much stronger binding. (***TEST QUESTION***: When given a set of structures, be able to tell which generates radical damage to DNA = Dactinomycin (aminoquinone)) s. **Mitomycin**: Prodrug, has 3 carcinostatic functional groups including quinone, carbamate and aziridine, results in DNA cross-linking. (***TEST QUESTION***: When given a set of structures, be able to tell which generates radical damage to DNA = Mitomycin (quinone)) t. **Bleomycin**: Natural products mixture, intercalates DNA, NOT inhibit topo-II, bleomycin hydrase converts terminal amide into carboxylate and deactivate the drug. 13. **Mitosis Inhibitors SLIDE 57 - 61** u. **Taxanes**: General **MOA** (**Enhance** polymerization, inhibit the function of microtubules during M phase), **structural features** (15-membered diterpenoid scaffold fused with an oxetane ring). i. Important drugs: **paclitaxel**, **docetaxel**, **carbazitaxel**. ii. **Epothilones**: same MOA as Taxanes, structure different but binding to the same binding site as Taxanes on polymerized b-tubulin, better water solubility and no p-gp affinity. v. **Vinca alkaloids**: General **MOA** (**Inhibits** polymerization, inhibit the function of microtubules during M phase), **structure features** (2 polycyclic segments), **Side effects** (Vincristine has more CNS toxicity, accidental intrathecal administration is lethal, vinblastine and vinorebine have more bone marrow suppression). i. Important Drugs: **Vincristine**, **Vinblastine**, **Vinorelbine** ii. **Spindle toxin conjugates**: **vedotin** inhibits cell division by blocking tubulin polymerization, too toxic to use alone, in conjugation with antibodies. 14. **Topoisomerase Inhibitors SLIDE 64 - 68** w. **Camptothecins**: General **MOA** (inhibit TOPO-I, active during the S phase, causing single and double strand breaks in the DNA and preventing relegation of single strand breaks), **structures** (chiral, extensively conjugated, amino-containing pentacyclic lactones), limited water solubility, lactone is liable to hydroxylation which reduce activity. i. Important drugs: **Topotecan** (IV dose, CYP3A4 metabolism, side effects). **Irinoteacan** (prodrug, bioactivation/metabolism, IV dose). ii. **Trastuzumab Deruxtecan**: drug antibody conjugate x. **Epipodophyllotoxins**: General **MOA** (Inhibit Topo-II, most active in S and G2 phase), highly water insoluble, requires solubility enhancers for IV infusion (hypersensitivity issue). 15. **Antimetabolites: SLIDE 71, 77, 79, 80, 83-87, 90** y. **Pyrimidine antagonists**: **MOA** (These agents inhibit pyrimidine synthesis during S phase an active metabolite (F-UMP) is incorporated into RNA to replace uracil and inhibits cell growth, while another active metabolite (5-F-dUMP) irreversibly inhibits thymidylate synthase.) i. **Uracil analogs (all prodrugs)**: **Fluorouracil** (active form, MOA), **Floxuridine** (active form), **Capecitabine** (active form, critical enzyme in bioactivation pathway) - **MOA** - active metabolite (5-F-dUMP) irreversibly inhibits thymidylate synthase. ii. **Cytidine analogs**: **Cytarabine** (ara-C) (triphosphate inhibits DNA polymerase and incorporated into DNA to terminate DNA synthesis in S phase; IV only). **Gemcitabine** (**triphosphate** inhibits DNA synthesis by incorporating into DNA, **diphosphate** inhibits ribonucleotide reductase; IV only). iii. More **cytidine analogs**: **azacitadine** and **decitabine**, triphosphates incorporated into RNA and DNA, also inhibits DNA methylation that stops gene silencing, IV dose. z. **Purine antagonists**: Inhibits initial step in purine biosynthesis (major for 6-mercaptopurine) and incorporated into both DNA and RNA (primary for thioguanine). i. Important drugs: **6-Mercaptopurine** (Prodrug, active thiopurine ribonucleotide inhibits initial step in purine biosynthesis, xanthine oxidase converts it to inactive metabolites, allopurinol can inhibit xanthine oxidase to cut the dose of this drug in half). **Thioguanine** (prodrug, incorporated into both DNA and RNA as major MOA). ii. **Adenosine analogs**: halogenated adenosine-based nucleosides, active forms are nucleoside triphosphates which either inhibit DNA polymerase or ribonucleotide reductase or incorporated into DNA and RNA. C2-halogen renders the compounds relatively resistant to the degradation by adenosine deaminase. iii. **Pentostatin**: ring-expanded purine ribonucleoside, inhibits adenosine deaminase, increase the efficacy of purine and pyrimidine analogs by blocking metabolism, inhibits DNA and RNA synthesis and incorporated into DNA. a. **Folate antagonist**: Interfere with the enzymes involved in the folic acid cycle, blocking purine and pyrimidine biosynthesis during S phase. i. Important drug: **Methotrexate** (inhibits DHFR and GAR, interfere with THF synthesis, purine synthesis and pyrimidine synthesis. Rescued by **leucovorine**). (***TEST QUESTION***: Know the name or structure of leucovorine as a rescue for MTX) 16. **Miscellaneous anticancer agents: SLIDE 92 - 95** f. **Tretinoin**: ATRA, oral dose for APL, first line, force APL cells to differentiate and stop them from proliferating. g. **Arsenic trioxide**: highly toxic, 2^nd^ line for APL, induce cancer cells to undergo apoptosis. h. **Asparaginase** and **Pegaspargase**: catalyzes the conversion of L-asparagine to aspartic acid and ammonia, deprives the leukemic cells of circulating asparagine, leading to cell death. Pegaspargase is the pegylated form, for ALL, allergic or hypersensitivity reaction is the major side effect. **Exam Review Summary: Traditional Chemotherapy** **1. DNA Alkylating Agents** - **Recognize Structural Features** - **Nitrogen mustards** (e.g., Cyclophosphamide) - **Platinum complexes** (e.g., Cisplatin) - **Organo-platinum complexes** - **Mechanism of Action** - **Alkylation of DNA**, leading to cross-linking - **Inhibition of transcription** by preventing polymerase access - **DNA fragmentation and dysfunction** - **Nitrogen Mustard SAR (Structure-Activity Relationship)** - Aliphatic vs. aromatic substitution affects: - **Activity** - **Selectivity** - **Toxicity** - **Oral bioavailability** - **Cyclophosphamide (Key Drug)** - **Prodrug** activated through metabolic pathways - Produces **toxic metabolites** (e.g., Acrolein) - Requires detoxification using **Mesna** to prevent toxicity (e.g., hemorrhagic cystitis) **2. Anti-Cancer Antibiotics** - **General Mechanism** - **Intercalation into DNA** - **Inhibition of topoisomerase II** - **Generation of free radicals → DNA damage** - **Drug-Specific Differences** - **Dactinomycin (Actinomycin D)** → Topoisomerase II inhibition + radical generation - **Mitomycin C** → Radical generation + DNA alkylation - **Bleomycin** → Only generates radicals to damage DNA - **Key Concept**: **All generate radicals---Know the structural features responsible for this ability** **3. Anti-Microtubule Agents** - **Two Major Classes** 1. **Taxanes (e.g., Paclitaxel, Docetaxel)** → Promote polymerization 2. **Vinca alkaloids (e.g., Vinblastine, Vincristine)** → Inhibit polymerization - **M-Phase Specificity** 1. These drugs **inhibit mitosis**, making them **M-phase specific** **4. Topoisomerase Inhibitors** - **Key Drugs: Podophyllotoxins & Camptothecins** - **Recognize them by structure or name** - **Mechanism of Action** - **Inhibit Topoisomerase I** → Camptothecins (**e.g., Irinotecan, Topotecan**) - **Inhibit Topoisomerase II** → Epipodophyllotoxins (**e.g., Etoposide, Teniposide**) **5. Antimetabolites** - **Two Major Classes** 1. **Purine & Pyrimidine Antagonists** (e.g., 5-Fluorouracil, Cytarabine, Mercaptopurine) 2. **Folate Antagonists** (e.g., Methotrexate) - **Key Drug: 5-Fluorouracil (5-FU)** 1. Inhibits **thymidylate synthase**, blocking DNA synthesis - **Methotrexate (MTX)** 1. **Inhibits folate metabolism**, essential for DNA synthesis 2. Causes **high toxicity** → requires **Leucovorin rescue therapy** if toxicity is severe