Anticancer Flashcards
What is cancer?
Cancer is caused by genetic changes that lead to unregulated cell proliferation, invasion of surrounding tissues, abnormal differentiation, and metastasis to secondary sites.
What are the main categories of cancer?
The main categories include carcinoma (epithelial cells), sarcoma (connective tissue), leukaemias (circulating white blood cells), and lymphomas (lymphatic organs).
What differentiates carcinoma subtypes?
Squamous cell carcinoma arises from cells lining cavities, while adenocarcinoma originates from mucous or fluid-secreting cells in organs like the lungs and pancreas.
What are the determinants of drug response in cancer treatment?
Factors include growth fraction, doubling time, total tumor mass, tumor heterogeneity, cell cycle phase, drug resistance, and host factors such as health and genotype.
What are the categories of anticancer agents?
Anticancer agents include cytotoxic agents, hormonal therapies, targeted therapies, monoclonal antibodies, and immuno-oncology drugs.
What are cytotoxic anticancer agents?
These agents target rapidly dividing cells and include alkylating agents, antimetabolites, microtubule-damaging agents, topoisomerase inhibitors, and certain antibiotics.
How do alkylating agents work?
Alkylating agents, like cyclophosphamide, form covalent bonds with DNA, causing cross-links that inhibit replication and transcription. These agents are cell cycle non-specific but are most effective on rapidly dividing cells.
What are antimetabolites and how do they work?
Antimetabolites disrupt DNA and RNA synthesis by mimicking natural metabolites. Methotrexate inhibits DHFR, blocking tetrahydrofolate production needed for thymidine and purine synthesis. 5-Fluorouracil inhibits thymidylate synthase, preventing pyrimidine synthesis.
How do microtubule-damaging agents work?
Agents like vincristine and paclitaxel bind to tubulin, disrupting microtubule dynamics, blocking mitosis at the M phase, and inducing apoptosis.
What are topoisomerase inhibitors and how do they work?
Topoisomerase inhibitors like etoposide (topoisomerase II) and irinotecan (topoisomerase I) prevent the unwinding and re-ligation of DNA strands during replication, causing DNA damage and apoptosis.
What are targeted therapies?
Targeted therapies inhibit specific molecular pathways, such as HER2 inhibitors (trastuzumab), EGFR inhibitors (gefitinib), VEGFR inhibitors (sunitinib), and tyrosine kinase inhibitors (imatinib).
How does trastuzumab (Herceptin) work?
Trastuzumab is a monoclonal antibody targeting HER2 receptors on cancer cells, blocking signaling pathways that promote cell proliferation and survival in HER2-overexpressing breast cancer.
What is the role of immuno-oncology?
Immuno-oncology enhances the immune system’s ability to recognize and destroy cancer cells through therapies like checkpoint inhibitors, cancer vaccines, and CAR-T cell therapy.
What is CAR-T cell therapy?
CAR-T cell therapy involves engineering T cells to express chimeric antigen receptors (CARs) that specifically target tumor antigens, enhancing the immune system’s attack on cancer cells.
What causes resistance to anticancer drugs?
Resistance arises from increased drug efflux (e.g., P-glycoprotein overexpression), enhanced DNA repair mechanisms, mutations in drug targets, and altered cellular signaling pathways.
What is multidrug resistance (MDR)?
MDR is caused by the overexpression of efflux transport proteins like P-glycoprotein, which pump drugs out of cancer cells, reducing their intracellular concentration and efficacy.
How can resistance to anticancer drugs be minimized?
Resistance can be minimized through combination therapies targeting different pathways, using intensive short-term regimens, and co-administering drugs that inhibit efflux pumps.
What are cell cycle-specific agents?
Cell cycle-specific agents target specific phases of the cell cycle, such as vincristine and paclitaxel (M phase) or methotrexate (S phase).
What are cell cycle non-specific agents?
These agents, like alkylating agents and cisplatin, kill both dividing and resting cells by inducing DNA damage or crosslinking.
What is the role of hormonal therapies in cancer?
Hormonal therapies, like anti-estrogens (e.g., tamoxifen) and androgen blockers, inhibit hormone signaling pathways in hormone-dependent cancers such as breast and prostate cancer.
What is the importance of the tumor microenvironment in cancer progression?
The tumor microenvironment, including angiogenesis, immune evasion, and stromal support, plays a crucial role in cancer progression and can influence treatment resistance.
What are immune checkpoint inhibitors and how do they work?
Immune checkpoint inhibitors, such as anti-PD-1 or anti-CTLA-4 antibodies, block inhibitory pathways that cancer cells use to suppress the immune system, restoring T cell activity against tumors.
