Exam 4 - Chemo drugs Flashcards
Children’s Oncology Group Study (COG)
- Randomized controlled study to test different drugs (on different arms) and compare outcomes
- Helps develop better treatment plans in the long run
Stages of Tumor Formation
- Hyperplasia - increase in size/number of cells (Ex: muscle cells).
- Metaplasia - once cell type changes to another; may see LOSS of FXC. (Ex: chronic smokers, lungs are exposed to hot gases. Ciliated cells are not there anymore, so they become scar tissue).
- Dysplasia - Lose uniformity and orientation of cells. May be reversible, but closer towards unchecked growth.
- Neoplasia - uncoordinated growth; lose response to suppressor genes.
>Immortalization of Telomerase.
>P53 triggers apoptosis of cells normally. Without this, you have unregulated growth.
How do you describe a benign tumor?
- Localized, enclosed in fibrous capsule
- Can be removed surgically
- Good prognosis
How do you describe a malignant tumor?
- Spreads and destroys adjacent tissue
- No capsule, high metastasis
- Fatal
Tumor Grading System
Grade 1: Closely resembles tissue of origin. Retains specialized function.
Grade 2: Moderately differentiated, less tissue of origin, increased mitosis
Grade 3: Poorly differentiated, tumor doesn’t resemble tissue of origin, increased variation, increased mitosis.
Grade 4: Very poorly differentiated, no resemblance to tissue of origin, highly variable, enhanced mitosis, metastatic.
Principles of Therapy (7)
- Single “clone-ogenic” tumor stem cell has potentil for unlimited replication.
- Different tumors have different growth patterns, which change based on disease.
- Gompertzian cell growth
- Treatment should involve removal of the tumor as the first step.
- Drug conc., exposure time, and freq. of administration is critical for effectiveness.
- Maximize drug concentration
- Protect patient - Early detection (pt. ed., screening, etc.).
- Toxicity
Neoplastic cells: desired effect.
Well-differentiated
Cells targeted more effectively.
As you lose the differentiation, it becomes harder to target cells.
Localized
Localized can be removed by surgery or radiation.
Disseminated, like leukemia, you need to do more drug therapy, bc its systemic.
Gompertzian Cell Growth
Each tumor takes a constant time to double its size. Growth fraction decreases as the tumor size increases.
Growth is initially rapid, then flattens out, because it outgrows the nutrient supply.
Time at diagnosis, how many tumor cells are there, approximately?
10^8 at Dx.
10^6 cells = 1 mm
10^9 cells = 1.24 cm = 1 gm
10^12 cells = 20 cm = 1 kg
First order cell kill:
Therapy gives you a fraction of the cells killed.
If you kill 99.9% of 10^12 cells, you still have 10^9 left of cells that can still grow.
Treatment should involve removal of tumor first.
When is surgery appropriate? Radiation? Chemo?
Surgery - well-localized and well-differentiated tumors.
Radiation - localized tumors, NOT easy to remove.
Ex: brain and pancreas.
Chemotherapy - Good for systemic cancers; will see systemic effects.Targets all rapidly dividing cells.
What happens in myelosuppression?
- Severely immunosupressed
- Develop neutropenic fever
- Put on BSA
Fever might be the only sign of infection. Can get fungal infections, resistant bugs, and viruses.
What kind of fruit do you give to a myelosuppressed patient?
- Orange or banana
- PEELED fruit
How do you AVOID checking temperature on neutropenic patient?
Rectum
- Worried about perforation and translocation of GI bugs.
- Can cause septicemia.
What are the dosage regimens?
High dose w/ intermittent schedule to allow for recovery of cells.
- Time for maximum susceptibility where drug acts in cell cycle and where tumor is in growth curve.
- Drugs given prolonged to hit the different cell cycles; want to hit when its dividing.
- Depends where tumor is in growth curve (good flow slow growing tumors).
Cell Cycle
- G0: resting phase, no division
- G1: enzyme synthesis prior to DNA synthesis, 18-30 hours
- S: DNA synthesis, 10-20 hours
- G2: pre-mitotic phase, protein and RNA synthesis 2-10 hours
- M-phase: Mitosis: cell division, 30-60 minutes.
Most non-malignant cells are in G0.
Anticancer drugs are not only selective for tumor cells. They target rapidly dividing cells as well.
Growth Fraction:
-Portion of cells actively dividing; early stages of growth
S fraction:
- Cells in S-phase
- More cells in S-phase means its more aggressive
Doubling time:
- Time necessary for tumor to double in volume.
- As tumor gets bigger, doubling time starts to slow down.
-Short doubling times are found in more aggressive tumors.
How do we design our dosage regimens?
Combination therapy
- Rare to see patient on one drug
- Minimize resistance
- Can use lowe doses of all drugs to limit toxicity
Adjuvant therapy
- Lots of drugs used to treat and minimize toxic effects
- Antiemetics
- Stimulate bone marrow
Patients get a big course of chemo, which knocks down their cells. Then we give them growth factors to stimulate growth of their healthy cells.
Toxicity: Kills cells with highest growth rates. What’s affected?
Neoplastic cells: desired effect.
- Bone marrow - willl cause myelosuppression and immune supression
- GI tract - oral and intestinal ulceration (stomatitis)
- Hair - Alopecia.
- Decreased sperm production and menstrual irregularities.
If you see a patient with stomatitis and mucositis, what are you concerned about?
May need to switch them to parenteral nutrition, because they won’t want to eat.
How do cells generate resistance to chemo?
- Drug not able to get into the cell (decreased uptake).
- Metabolism of drug more quickly.
- Able to repair DNA more quickly.
When you develop resistance, need to switch to a different type of therapy.
Cancer chemotherapy (Synthetic)
- Alkylating agents
- Antimetabolites
- Alkylating agents: alkylate purine/pyrimidine bases, blocks DNA synthesis for cancer cells.
- Antimetabolites: structural analogs of purines, pyrimidines, or cofactors needed for DNA synthesis; added to chain and prevent further replication.
Cancer chemotherapy (Natural)
- Plant alkaloids
- Antibiotics
- Biological response modifiers
- Hormonal agents
- Immunostimulants
PA: inhibit mitotic spindle formation and topoisomerase II.
Abx: intercalate DNA base pairs and break strands.
BRM: antibodies, kinase and GF inhibitors.
HA: inhibit hormone sensitive tumor growth.
IM: stimulate immune system
Topoisomerase:
Cuts single strand breaks in DNA to unwind and relax the DNA.
What antibiotics target bacterial topoisomerase?
Flouroquinolones
What type of cancer chemotherapy has greater specificity for cancer cells?
- Biological response modifiers
- Hormonal agents
- Immunostimulants
Have less side effects
ALKYLATING AGENTS
…
ALKYLATING AGENTS
Nitrogen Mustards
- Mechlorethamine (Mustargen)
- Cyclophosphamide (Cytoxan)
- Ifosfamide (Ifex)
- Chlorambucil (Leukeran )
- Melphalan (Alkeran)
-Come from mustard seeds and mustard gas.
ALKYLATING AGENTS
Nitrosoureas
- Carmustine (BCNU)
- Lomustine (CCNU)
- Streptozocin (Zanosar) (targets pancreatic b-cells)
ALKYLATING AGENTS
Other
- Dacarbazine (DTIC)
- Procarbazine (Matulane)
- Temozolomide (Temodar)
- Altretamine (Hexalan)
- Busulfan (Myleran )
ALKYLATING AGENTS
Platinum coordination complexes
- Cisplatin (Platinol)
- Carboplatin (Paraplatin)
- Oxaliplatin (Eloxatin)
Which nitrosureas agent causes Type 1 Diabetes?
Streptozocin
- Targets pancreatic beta cells
- Good for pancreatic cancer, deadly
What alkylating agent causes pulmonary toxicity?
Busulfan (Myleran)
General Properties of Alkylating Agents:
Nitrogen Mustards
Nitrosureas
Others
Platinum-based
- Cytotoxic to rapidly dividing cells
- Not cell-cycle specific (G1 and S)
- Bind to purines and pyrimidines; so doesn’t have to be in a state where its actively dividing.
- Carcinogenic
- Teratogenic - Make sure patients are using protection to PREVENT pregnancy.
SE:
- Bone-marrow suppression
- Epithelial cell damage (oral & GI mucosa) - diarrhea, stomatitis
- Amenorrhea, decreased spermatogenesis
- CNS mediated nausea and vomiting
- Secondary tumors (leukemia’s)
- All can cause pulmonary fibrosis
Because AA cause pulmonary fibrosis, what do you need to monitor before/during/after drug?
Serial PFTs
Alkylating Agents MOA
Nitrogen Mustards
Nitrosureas
Other
Platinums
- AA bind to the nitrogen atoms of guanine, adenosine, and cytosine (DNA)
- Formation of cross links with adjacent bases, causes damage which inhibits DNA replication.
- More DNA strand breaks, increases P53 gene activity (APOPTOSIS).
- Mispairing can cause RNA polymerase to code for wrong DNA and lead to cell death.
- Depurination (removes purine from sugar backbone).
- Ring cleavage increases, decreased periods of DNA synthesis phase.
Nitrogen Mustards
Where were they developed from?
Nitrogen Mustards
(Alkylating agents)
- Mechlorethamine
- Cyclophosphamide
- Ifosfamide
- Chlorambucil
- Melphalan
- WW1: Mustard gas
- Strong vesicant
- Worry about extravasation
Vesicant:
- Causes vesicles (blistering) and skin damage
- Extravasation to underlying tissue can cause damage.
- Port needed; to have central access.
- Warm compress
- Cold compress
- Solvents
Mechlorethamine (Mustargen)
- Nitrogen Mustard
- Given IV
SE:
- N/V “huge”
- Myelosuppression
- Stomatitis
- Alopecia
- ↓ reproductive functions
Myelosupression can cause them to die of secondary infections.
Cyclophosphamide (Cytotoxan)
- Nitrogen Mustard
- Oral, IV, (metabolic activation)
- Used in breast, lung, testicular, ovarian cancer, CLL
SE:
- Drug is broken down into acrolein molecule, which causes hemorrhagic cystitis.
- Binds to sides of bladder and breaks down tissue.
- Antidote: Mercaptoethane sulfonate (MESNA)
- N/V, alopecia
- Immunosupression
What causes hemorrhagic cystitis?
Cyclophosphamide (Cytotoxan)
How do you prevent hemorrhagic cystitis when giving Cyclophosphamide (Cytotoxan)?
Antidote: Mercaptoethane sulfonate (MESNA)
Ifosfamide (Ifex)
- Nitrogen Mustard
- CYP3A4 metabolic activation
- Used for sarcoma, testicular cancer
- Same toxicities as Cyclophosphamide (less potent)
SE:
- Neurotoxicity: hallucination, confusion, and worsening depression.
- Cystitis (MESNA can be hung to prevent damage in the first place).
- Increased PLT suppression
Melphalan (Alkeran)
- Nitrogen Mustards
- Used for multiple myeloma, bone marrow transplants
- Orally , IV
Toxicity
- Bone marrow suppression
- No alopecia
- LESS N/V
Chlorambucil (Leukeran)
- Nitrogen Mustards
- Given orally, slow depression of bone marrow
Limited toxicity?
- GI discomfort
- Pulmonary fibrosis
- Seizures’
- Dermatitis
Nitrosureas
- Carmustine
- Lomustine
- Streptozocin
- MOA: Alkylate DNA and carbamoylate proteins.
- Bind to proteins to inhibit their function, which results in DNA damage.
-Lipophillic: can get into the blood-brain barrier to reach brain tumors, melanoma, non-Hodgkin’s lymphoma
SE:
- MORE myelosuppression
- Pulmonary fibrosis
- Secondary Leukemia
- Renal toxicity
Dacarbazine (DTIC) (IV) (Triazene)
Procarbazine (Matulane) (oral) (Methylhydrazine)
-MOA: Activation by CYP P-450 system to Diazomethane (MTIC), cytotoxic agent
What toxicity is seen with Dacarbazine and Procarbazine?
SE:
- Nausea and vomiting - SEVERE!!!
- High emetogenicity, will change drugs used to treat.
- Myelosuppression
- Alopecia
- Flu-like syndrome, fever, chills, muscle pain
- CNS depression (procarbazine)
- Renal and Hepatotoxicity
- Leukogenic (procarbazine)
What drug causes CNS depression and is leukogenic?
Procarbazine!
Temozolomide (Temodar) (PO)
-Drug of choice for malignant gliomas together with radiation
-Mechanism similar to Dacarbazine
Prodrug.
Altretamine (Hexalan) (oral)(Ethylenimines)
- Activated to alkylating agent by enzyme.
- Second line agent for ovarian cancer
SE:
-Neurotoxicity: ataxia, depression, confusion, hallucinations
Busulfan (Myerlan, Busulfex) (oral)(Alkyl sulfonates)
MOA, SE
- Alkyl sulfonate acts like mustards
- Acute myelosuppression
SE:
- Seizures
- PULMONARY FIBROSIS!!
- Busulfan lung, 3 years fatal
Cisplatin (IV)(Platinum Complexes)
MOA, uses
- MOA: Cross-link nitrogen on guanine or adenine within same strand.
- Sensitizes some tumors to radiation; give doses of chemo before a pt gets radiation. Make cancer cells rapidly divide again to get a higher fraction for radiation to hit.
- Reacts with sulfhydryl groups
Cisplatin (Platinol-AQ)(Platinum Complexes)
Toxicity
- SEVERE Nausea, vomiting
- NEPHROTOXICITY
- Ototoxicity - hair cell damage (baseline follow up hearing tests needed)
- Mild myelosuppression
-Sulfhydryl rescue - Na Thiosulfate to limit toxicity; helps detoxify toxic compounds.
How do we avoid nephrotoxicity for patients on Cisplatin?
- NEPHROTOXICITY
- Hydrate patient (1-2 liters of saline)
- Amifostine (Ethyol) thiophosphate: renal protective agent
What is a sulfhydryl rescue?
- Give Na Thiosulfate; donates sulfur groups to detoxify toxic compds.
- Ex: Cisplatin
Platinum ComplexesCarboplatin (Paraplatin) MOA, Toxicity
-MOA: Requires activation, slower, less reactive than Cisplatin
Toxicity:
- Moderate nausea, vomiting
- MORE myelosuppression
Oxaliplatin (Eloxatin)
Uses, SE
-Used for GI and colorectal, ovarian, head and neck cancer
SE:
-Peripheral neuropathy!! “Stocking glove” pattern.
How do you develop resistance to chemotherapy drugs?
↓ Ability to enter cells
Efflux pumps
↓ Activation and conversion of pro-drugs
Drugs not activated; less effective.
↑ Intracellular glutathione to bind Alkylating agent before it hits the DNA
↑ DNA repair mechanisms
Upregulated to overcome alkylation effects
Resistance develops rapidly when used ALONE. Need to use MULTIPLE DRUGS to avoid resistance!!!!!!!!!
ANTIMETABOLITES
Used in combination with alkylating agents.
Folic Acid Analogs
Methotrexate (Trexall, Rheumatrex)
- Also used in RA.
- Immune suppression
Trimetrexate (Neutrexin)- PJP
Pemetrexed (Alimta)
Pyrimidine Analogs
- 5-Flurouracil (5-FU)
- Floxuridine (FudR)
- Capecitabine (Xeloda)
- Cytarabine (ara C, Cytosine arabinoside)