Oncology Flashcards
6 modalities/hallmarks of cancer
- Growth factor independence (GOF)
- Loss of response to anti-growth signals/differentiation signals (LOF)
- Resistance to apoptosis
- Recruitment of blood/lymph
- Invasion and metastasis
- Limitless replicative potential
Growth factor independence
- typically related to gain of function oncogenes
Proto-oncogenes
normal genes with important roles in regulating division, differentation, survival, movement –> mutate to oncogenes (GOF)
PI3K Pathway
- PI3K phosphorylates lipid on the cytoplasmic side of membrane
RTK (e.g. EGF receptor) –> activate PI3K–> converts PIP2 –> PIP3 –> docking site for PH domains (e.g. in AKT)–> AKT/PKB –> phosphorylation of proteins
- Involved in many signaling events
- Disregulation can have significant oncogenic downstream effects
Warburg effect
elevated AKT activity due to PI3K mutation –> increased glucose transport & glycolysis (basis of PET)
PTEN
- most common mutation leading to elevated PI3K activity
- PTEN converts PIP3–> PIP2 (opp. of PI3K)
- usually via deletion of PTEN or silencing of locus
- LOF is usually more common than GOF
Tumor suppressor
genes in which loss of function promotes cancer (e.g. PTEN)
p53
- tumor suppressor gene
- activates cell cycle arrest & apoptosis
- most cancers have p53 mutation
- DNA-binding transcription factor
- regulates
- p21 cyclin inhibitor
- GADD45- DNA repair
- Bax, Puma, Noxa- pro apoptosis
- MDM2- self-regulation
- accumulates in cancer cells b/c loss of autoregulation
Li-Fraumeni Syndrome
patients with one germ-line mutant copy of p53 gene –> prone to leukemias, sarcomas, breast, brain cancers associated with loss of remaining functional p53 allele in those cells –classic example of “loss-of-heterozygosity” (LOH).
Apoptosis
- highly ordered, ATP-dependent process-proteins, subcellular components dismantled by proteases (“caspases”)and nucleases
- membrane blebbing produces “apoptotic bodies” containing cellular debris, which are then engulfed by macrophages and other cells
- avoids release of cellular components that could trigger a damaging inflammatory response.
Caspases
- proteases that use conserved cysteine residue in their active site to cleave other proteins after aspartate residues in apoptosis
- initiators
- effectors/exectuioners
- present as procaspases until stimulus initates apoptosis
Intrinsic apoptotic pathway
mitochondrial membrane loses integrity –> cytochrome C released from mitochondria –> binds Apaf 1 to form apoptosome –> recruits procaspase 9 –> cleaves executioner caspases –> apoptosis
BCL related proteins
- promote apoptosis - Bax, Bax
- inhibit apoptosis - Bcl2
- apoptosis determined by equilbirium of these stress-responding factors
Extrinsic apoptotic pathway (death receptor)
- Fas (or other TNF death receptor) receptor binds FasL/–> recruits FADD/TRADD—> recruits intiators 8 and 10 which autoactivate and trigger effectors 8/10 –> DISC
Ways cancers bypass apoptosis
- over expressing antiapoptotics like Bcl2
- downregulating proapoptotics like Bax, Bak
- losing p53 which induces proapoptotics Bax, Puma, Noxa
- downregulating death receptors Fas, Trail
Hayflick Limit
- replicative senescence:
- most cells: division of cell –> some DNA lost –> limits number of replications
- if continued replication –> breakage fusion bridge cycle would occur –> inappropriate fusing of chromosomes
Telomerase
- telomerase adds extra telomeric DNA to some some cells (stem cells, lymphocytes)
- dysregulation ensures stable chromosomes for cancer
Angiogenic switch
- recruitment of blood vessels to ensure tumor growth > 2mm
- balance between
- inhibitors
- statins
- thrombospondin
- activators
- VEGF
- FGF
- EGF
- PDGFB
- inhibitors
Tumor vasculature
highly anomalous because of inconsistent equilibrium between pro/anti angiogenic factors
VEGF
- vascular endothelial growth factor –> stimulates EC division, survival, differentiation, movement –> master regulator
- main form = VEGF A
- binds to tks on ECs (VEGFR1 and 2) –> angiogenesis
VEGF blockers
antiangiogenic therapy
- bevacizumab = mab
- sunitinib/sorafenib = kinase inhibitors
Seed and Soil Metastasis
- cancer cells follow venous and lymphatic drainage
- some tumor cells may adher in or survive better in certain organs
Importance of Philadelphia chromosome
- encodes fusion protein BCR-ABL = oncogene with abnormal tk activity
- t (9;22) –> BCR intiator, ABL gene
- present in 100% CML, 30% AML
- Tx: Gleevec/Imatinib
FFPE
Formalin fixed parafin embedded –> cut tumor specimen –> laser capture DNA –> PCR –> identify markers, resistance
BRAF mutation
- GOF V600E most common (val/glu)
- predicts resistance to Vemurafinib
- BRAF mutation
- 40-60% melanoma
- 40-70% papillary thyroid
- 10% metstatic colorectal
Sequencing Read Length
number of sequential images taken
Sequencing Read Depth
number of DNA fragments for a given position
Reactive/benign disorders
- polyclonal expansion of different kinds of cells
- leukemoid reaction - expansion of granulocytes in response to bacterial infection
- lymphadenitis- inflammation of lymph nodes
Neoplasms
- clonal expansion of a single cell
- uncontrolled expnasion –> organ replacement –> functional compromise –> death
Leukemia
- neoplasms that involve bone marrow and spill into peripheral blood
- blood forming elements:
- granulocytes
- red cells
- megakaryocytes
- all lymphoblast-related are leukemias
- blood forming elements:
Lymphoma
- solid mass tumor of lymph nodes, spleen, extranodal sites (GI tract, skin)
- neoplasm of mature lymphocytes
Acute/precursor neoplasm
- immature early undifferentiated state
- blast
Chronic/peripheral neoplasm
mature differentiated cell neoplasm
Lymphomas- morphology
- size: small vs large (size of a mature lymphocyte vs. histiocyte nucleus)
- growth pattern: nodular vs. diffuse
- morphology is not the best predictor of behavior since some small cell lesions can be aggressive and indolent lesions can be unresponsive to therapy
Secondary lymphoid follicles
- follicle which develops after antigen presentation with B cells undergoing class switch and somatic hypermut.
-
germinal center: C10+BCL6+BCL2- –> need apoptosis working during proliferation so must be bcl2-
- dark zone: proliferating centroblasts
- light zone: mature centrocytes
- mantle of naiive B cells: CD10-BCL6-BCL2+
- undelrying CD21+ follicular dendritic meshwork
- mantle of plasma cells
Lymphomas- immunophenotype
- expression pattern of a surface and intracellular proteins in a cell population
- benign (polytypic) vs. neoplastic (monoclonal)
- lineage (CD3/T vs CD19/B)
- stage of diff. (Tdt vs. surface Ig)
- aberrant expressions
- CD5+ B cells
- mature T cells w/o pan-t antigens
- assessed by:
- flow cytometry
- immunohistochemistry
Immature B cell markers
Tdt- expressed by immature lesions
CD19
Mature B cell markers
all: CD19, CD20
mature: k/l light chains
germinal: CD10, BCL6 (secondary follicles)
all except germinal: BCL2
Immature T cell markers
Tdt
CD1a
cCD3
Mature T cell markers
CD2
sCD3
CD5
CD7
also: CD4/8
Lymphomas-genotype
- gross chromosomal rearrangements that lead to abnormal gene expression
- B cells undergo mutlipel rounds of damage –> more common neoplasms
- Ig rearrangement in marrow
- somatic hypermut./class switch
- Examples:
- Burkitt’s = t(8;14) IgH/Myc
- Follicular = t(14;18) IgH/BCL2
What does lymphoma genotype prove?
- clonality
- specific tumor subtype
Lymphomas- normal cell counterpart
neoplastic cells recapitulate morphology, immunophenotype of progenitor cells
Lymphomas-clinical features
- variable: asymptomatic vs. constitutional
- “type B” symptoms: fever, night sweats, weight loss
- dictated by affected site & tumor biology
- lymph nodes = lymphadenopathy
- extranodal = organ dysfunction
- marrow involvement = suppression
- plasma cell = bone destruciton
Lymphomas-characterization by clinical features
- lymphoblastic = pediatric
- extranodal marginal zone = mucosal spread
B Cell NHL
- derived from mature B cells
- neoplasms capitulate function of progenitors
- bone marrow involvement common (stage IV) –> interstitial except follicular
- liver/spleen involvement common
- difficult to cure
- can transform to aggressive
- IgH/14 involved in some important translocations
- indolent: follicular, cll/sll, marginal
- aggressive: DLBCL
- highly aggressive: Burkitt’s
Follicular lymphoma immunophenotypic profile
B: CD19+/CD20+/CD(2-8)-/
Germinal Center: CD10+
Aberrant: BCL2+
low Ki67 –> disease of cells surving a long time//not a disease of cells proliferating
CLL/SLL immunophenotypic profile
B: CD19+/CD20+
T: CD5+
Non-germinal: CD10-/BCL6-/BCL2+
Marginal lymphoma immunophenotypic profile
No distinct marker
B: CD19+CD20+
Not Germinal: CD10-/BCL6-/BLC2+
Follicular lymphoma- clinical features
- t(14;18) –> BCL2+
- General lymphadenopathy
- BM involvement common (Stage IV) –> represents hematogenous spread
- nonaggressive
- spleen and liver involvement common
- fine diffuse nodularity –> expansion of splenic white pulp
- in extensive disease –> red pump also
- occasional peripheral blood involvement –> small cleaved cells
- extranodal involvement uncommon
Follicular lymhoma- prognosis
- Indolent- waxing/waning course –> 8 years
- largely incurable
- Often transforms to diffuse B cell lymphoma –> 1 year survival
- Tx: observation, symptom relief, anti-CD20
Follicular lymphoma- morphology
- germinal center B cells
- nodular appearance- lots of germinal centers
- crowded, back to back
- lack polarity (thick/thin ends)
- no tingible body macrophages
- no discernable mantle
- paratrabecular aggregates
- grade 1 = more nodular and more centrocytes –>indolent
- grade 2/3 = more than 5 centroblasts/hpf

CLL/SLL: Chronic lymphocytic leukemia/Small lymphocytic lymphoma
- spectrum cancer
- circulating cells –> leukemia
- solid mass –> lymphoma
- CLL = most common adult leukemia
- SLL = uncommon
CLL/SLL-clinical features
- 13q/trisomy 12/deletion 11q/deletion 17p
- usually asymptomatic//6th decade presentation
- general lymphadenopathy
- low grade lymphoma for most of life
- usually progresses to Stage IV
- common hepatosplenomegaly
- peripheral blood involvement
- immune dysregulation
- autoimmune RBC/platelet
- AIHA
- thrombocytopenia
- autoimmune RBC/platelet
CLL/SLL- prognosis
- variable survival
- Group 2 > Group 1 prognosis
- transformations
- prolymphocytic leukemia
- richter’s transformation –> DLBCL
Richter’s transformation
- transformation of CLL/SLL to DLCBL
- same mechanism employed in all indolent lymphomas
CLL/SLL- morphology
- unknown source
- diffuse effacement of architecture
- proliferation centers: “pseudofollicles”
- prolymphocytes/paraimmunoblasts
- small round lymphocytes with condensed chromatin, scant cytoplasm, and fewer large cells. also see smudge cells
- interstitial marrow infiltrate: nodular or diffuse
CLL/SLL Group 1 and 2
- unmutated IgV
- no SHM/naive
- Zap70+
- aggressive
- hypermutated IgV
- post GC/mature
- Zap70-
- indolent
Marginal zone lymphoma
- 3 diseases
- nodal marginal zone lymphoma
- splenic marginal zone lymphoma
- extranodal marginal zone (MALT) –> most common
MALT MZL-clinical features
- t(1;14) API2-MALT1
- t(11;18) IgH/BCL10
- t(14;18) IgH/MALT-1
- associated with chronic inflammation (e.g. pylori, jejuni, borrelia, chlamydia)
- low grade with transformation to DLCBL
- Tx: antibiotics/antiviral
S-MZL
splenic marginal zone lymphoma associated with Hep C
MALT/MZL
NF-kB pathway
- responsible for stimulating cell survival and proliferation
- MALT–> BCL10 or API2MALT1 –> binds MALT1 –> induction of NF-kB
Plasma cells
- terminally differentiated B cells:
- CD19+, CD138+, CD56-
- in lymphoma, CD56+ hone plasma cells to marrow
- CD19+, CD138+, CD56-
- lymph nodes and bone marrow
- clockface nuclear chromatin, perinuclear clear zone, gray cytoplasm, eccentric nuclei

Multiple Myeloma
- plasma cell neoplasm
- most common lymphoid neoplasm in AA, 2nd most in whites
Multiple Myeloma- clinical features
- multifocal –> areas of hematopoeisis (vertebrae–>emergency!!!), ribs, skull)
- anemia (from marrow replacement and renal failure)
- hypercalcemia (osteoclast activation)
- rouleaux/blood viscosity increase –>neurologic/thrombotic
- bone destruction
- pain
- osteolytic lesions –> “punchout”
Crab Plaits
C - calcium is high
R - renal failure
A - anemia
B - bone disease, bone pain, Bence-Jones protein (a paraprotein)
P - paraproteins (useful for monitoring patient)
L - LDH (again for monitoring)
A - amyloidosis (a complication)
I - immune paresis (suppression of Ig, a complication)
T - thalidomide (treatment)
S - stem cell transplant (treatment)

Multiple Myeloma- morphology
Paraprotein/Bence Jones
- M (monoclonal component) Ig from plasma cells in monoclonal gammopathies
- benign = MGUS (monoclonal gammopathy of undetermined significance)
- malignant = Multiple Myeloma
- Bence Jones = excess heavy or light chains secreted in MM –> measure in urine–> severity
- 50% IgG K>L
- 25% IgA K>L
- Consequences
- Cryoglobulinemia (Raynauds)
- Renal failure
- Amyloidosis
- Bleeding
- Immunosuppression
Humoral Immune Paresis
suppression of normal polyclonal Ig production in myeloma patients
Cast nephropathy
Amyloidosis
oversecreted clonal serum Ig settle out in beta-pleated sheets to form tissue deposits in end organs (e.g. renal glomeruli)
Multiple Myeloma- anemia
- cast nephropathy
- proximal tubulopathy from hypercalcemia and toxic reabsorption of light chains
- amyloidosis
results in uremia/hypovolemia, loss of epo (+marrow infiltration) –>anemia
DLBCL
- common NHL
- evolves from low grade lymphoma or denovo
- presents at single site-nodal or extranodal
DLBCL-clinical features
- rapidly enlarging symptomatic mass at single nodal or extranodal site (vs. indolent)
- commonly GI
- rare BM involvement
- associated with immunocompromise
- EBV
DLBCL-gross pathology
- homoegenous fish-flesh tissue replacement
- hemorrhage, necrosis, fibrosis
DLBCL-morphology
International Prognostic Index (IPI)
- most useful predictor of prognosis in DLBCL (50% do poorly)
Burkitt’s Lymphoma
- endemic (malaria belt) –> EBV in kids
- sporadic (western) –>rare in adults
- immunodeficiency –> HIV/EBV
Burkitt’s Lymphoma- clinical features
- high LDH
- endemic: facial bones (sometimes ovary, kidney, breast)
- sporadic: ileocecal/abdominal (sometimes ovary, kidney, breast; rare LN)
- immunodef: LN/BM
- EMERGENCY!!!
Burkitt’s Lymphoma- morphology
cMYC pathway
- endemic: defective t cell immunity –> EBV B cell proliferation –> t(8,14) –> cMYC overexpression
- sporadic/immunodef. also cMYC related
Cancer screening ages:
Cervical
Colon
Prostate
Breast
Cervical: 21 every 3y
Colon: 50 annual fobt, colonoscopy//fs//dcbe every 10y
Prostate: 45 PSA yearly
Breast: 21 CBE every 3y; 40, annual mammogram
TNM Cancer Staging
- T: size/extent of involvement of tumor (1-4)
- N: nodal involvement 0/1
- M: presence of metastasis 0/1
Cachexia Syndrome
fatigue & weight loss due to inflammatory factors like TNF during cancer
Paraneoplastic Syndrome
tumor produces pseudo/hormones:
- PTH = hypercalcemia
- gastrin = ulcers
- EPO = polycythemia
- paraprotein = hyperviscosity
Rationale for radiation therapy
cancer cells are rapidly dividing/less able to repair damage and their DNA is more susceptible to ionizing radiation
Direct vs. Indirect ionization
- Direct = damage directly to DNA
- Indirect = damage to DNA via reactive intermediates
2 methods of radiation delivery
- external beam rt (EBRT)
- internal rt (brachytherapy)
3 main types of EBRT
- Photons (x rays from linear accelerator)
- Light charged particles (electrons)
- Heavy charged particles (protons, carbon)
Radiosensitivity
in vitro survival of cells vs. dose
Radioresponsiveness
measurable change in tumor size during/after treatment –> correlates with radiosensitivity
Therapeutic Index
relative effect of treatment on tumor compared to damage of normal tissue
Acute vs. Late Toxicity
cells rapidly turning over (skin, oral mucosa, GI epithelium) respond before other tissue loss
Fractionation and the 4 R’s of radiobiolo’s
- need to split up RT dose to minimize tissue damage
- reassortment
- reoxygenation
- repair
- repopulation
Neoadjuvant vs. Adjuvant RT
preop vs. post op decision about how much RT to give to patient
Chemotherapy as a radiosensitizer - 5 effects
concurrent chemo during RT can help make radiation work better//help eliminate micrometastases
- enhancement of radiation damage
- inhibit cell repair
- accumulate cells in radiosensitive cell cycle stage
- work against hypoxic cells
- inhibit accelerated repopulation of tumor cells
Bragg Peak Effect
A pronounced peak on the Bragg curve which plots the energy loss of ionizing radiation during its travel through matter. For protons, α-rays, and other ion rays, the peak occurs immediately before the particles come to rest. The phenomenon is exploited in particle therapy of cancer, to concentrate the effect of light ion beams on the tumor being treated while minimizing the effect on the surrounding healthy tissue.
Proton therapy in Hodgkin Lymphoma
mediastinal radiation puts heart, lung, breast tissue at risk in young patients –> proton accelerator –> high energy protons
Hodgkin Lymphoma
- lymphoma with
- a significant minority of neoplastic Reed-Sternberg cells
- a larger and pleomorphic background of non-neoplastic reactive inflammatory cells
- constitutive activation of NF-kB
- activation of JAK-STAT
- relatively uncommon –> bimodal age dist.
- associated conditions: EBV, immunodeficiency, HIV, social class
Hodgkin Lymphoma- clinical features
- painless supradiaphragmatic (cervical) lymphadenopathy
- anterior mediastinum = nodular sclerosis
- axial/centripetal node involvement
- fever, weight loss, night sweats
- cytokine soup –> B symptoms
- opportunistic infections –> TB, fungi, HSV
- unifocal disease –> predictable lymphatic spread
Hodgkin Lymphoma- morphology
- excisional lymph node biopsy
- normal nodal architecture is effaced
- sea of reactive inflammatory cells
- Reed-Sternberg “owl eye” cell
Reed-Sternberg cell
- germinal center B cell derived
- associated with Hodgkin Lymphoma
- owl eye bilobed nucleus
- abundant cytoplasm
- eosinophilic nucleoli
- many variants
- often express CD30 (nonspecific TNF family)
*
Classical Hodgkin Lymphoma/CHL
- diffuse or nodular growth
- class RS cells
- CD15+/CD30+/PAX5+CD20+/-/CD45-
- background = more t cells
- stage ii or iii
4 types
- nodular sclerosis
- mixed cellularity
- lymphocyte depletion
- lymphocyte rich
Nodular Sclerosis
- commonest CHL
- nodular pattern + fibrotic/sclerotic bands
- necrosis common
- lacunar RS cells
- staging
- one nodal
- two nodes on same side
- both sides of diaphragm
- disseminated
- A: absence of symptoms
- B: presence of weight loss, fever, night sweats
- Tx: ABVD multidrug chemo (risk of sterility, AML) or BEACOPP
*
Acute leukemia
- hematologic malignancy in which rapidly progressive marrow failure occurs –> bm replacement by undifferentiated tumor cells –> arrested at blast stage
- most common pediatric cancer
- require small number of cooperating mutations (promote growth + impair differentiation)
Acute leukemia-clinical features
- t(9;22) BCR-ABL or t(15;17) PML-RARa
- abrupt onsent of bone marrow failure
- pancytopenia of normal blood cells
- infections, fatigue, bruising, bleeding
- increased blood viscosity
- sludging and microthrombi–> leukostasis
Acute leukemia-morphology
- maturational arrest at blast phase
- cytoplasmic granulation
- Auer rod: azurophilic cytoplasmic inclusion in myeloblasts –> myeloid related
PML-RARa Pathway
- defective retinoic acid receptor fails to initatie gene expression in response to physiologic dose ofretinoids
- associated with acute promyelocytic leukemia
- Tx: ATRA –> restores transcription
Left-shift
relative increase in immature hematopoietic development from what is expected
Leukemoid Reaction
normal release of polyclonal immature and maturing cells into circulation in response to stress or medications
Lymphoid Cells
B/T lymphocytes, plasma cells, NK cells
Myeloid Cells
granulocytic, monocytic, erythrocytes, and magakaryocytes
Chronic Myeloproliferative Neoplasms/Disorders
- clonal expansion of transformed stem–> terminally differentiated cells
- predisposed to transformation to acute leukemia
- tk dysregulation
- bone marrow cavity fibrosis
- hepatosplenomegaly
- polycythemia vera = erythrocytes
- essential thrombocythemia = platelets
- cml = neutrophil, monocyte, eosinophil, basophil
Chronic Myelogenous Leukemia (CML)
Classical MPN-Polycythemia Vera
- endogenous erythroid colony formation (EEC)–> growt without epo (JAK mutation)
- upregulation of BCL-X (like BCL2)
- Tx: phlebotomy, aspirin, hydroxyurea, interferon, Jak2 inhibitors
Chronic Myelogenous Leukemia- clinical features
- commonly asymptomatic –>incidental finding
- splenomegaly
- weight loss, fatigue
- high blood count
- hyperuricemia –> gout/stones
- pseudohyperkalemia, hypoxemia, hyopglycemia
- left shift
- very high b12, high LDH
- phases
- chronic-months to years
- accelerated-1 year
- blast crisis (acute leukemia) -3-6 months survival
“Classical” MPN
- Philadelphia chromosome negative
- excess production of one or more lineages of mature blood cells and/or bone marrow fibrosis
- complicated by predisposition to bleeding/thrombosis, extramedullary hematopoeisis
Classical MPN-Polycythemia Vera-clinical features
- may be asymptomatic with high hemoglobin
- clots
- hypermetabolism (gout, stones, sweating)
- hyperviscosity (from high hematocrit) –> congestion (e.g. retinal)
- aquagenic pruritis
- ruddy cyanosis
- vasomotor symptoms (erythromelalgia)
- bleeding
- splenomegaly
Classical MPN-Essential thrombocytosis
Classical MPN-Essential thrombocytosis-clinical features
- asymptomatic
- clots
- bleeding
Classical MPN-Primary myelofibrosis (PMF)
- myeloproliferative disease in which the proliferation of an abnormal type of bone marrow stem cell results in fibrosis, or the replacement of the marrow with collagenous connective tissue fibers
- highest risk of transformation to AML
- Tx: palliative, thalidomide, JAK2 inhibitors (ruxolitinib), stem cell transplant
Classical MPN-Primary myelofibrosis-clinical features
- anemia, abnormal platelets and wbc
- fatigue, weight loss, fever “B” symptoms
- splenomegaly
- leukoerythroblastic blood smear
- bone marrow fibrosis
Classical MPN-Primary myelofibrosis-morphology
p53 vs Rb phosphorylation
- when p53 is phosphorylated = do not enter cell cycle
- when Rb is phosphorylated = enter cell cycle
4 key effects of chemotherapy
- damage DNA
- inhibit DNA synthesis
- inhibit DNA replication
- inhibit mitosis
4 reasons cancer cells are susceptible to chemo
- contain mutations
- have impaired DNA repair mechanisms
- are addicted to specific signals
- divide regularly
Log-kill model
- cell kill is proportional to tumor mass
- chemo killing follows first order kinetics
- single dose won’t affect noncycling cells’
- probably true for small tumors but not in large:
- cumulative toxicity
- tumor heterogeneity
- development of resistance (by the time enough doses delivered)
Norton-Simon hypothesis
Gompertzian growth
exponential growth of cancer cells cannot go on forever
Modes of chemo drug resistance
- intrinsic
- sanctuary sites
- chemical properties
- acquired
- multidrug resistance
- enhanced DNA repair
- mutation of drug targets
Acquired resistance- MDR
mediated by p-glycoprotein (ATP pumps that remove drugs from cells)
Acquired resistance- Enhanced DNA Repair
- mediated via enzymes that repair damaged DNA
- AGT:
- PARP1
- XCCR1: base excision repair
- cisplatin: DNA excision repair
Acquired resistance- alteration of drug targets
drugs that target receptors or enzymes are most prone b/c of gatekeeper mutations in tk’s that can up/down regulate enzymatic targets
Pharmacologic Sanctuaries
- hard to reach tissues via transport constraint
- brain/testis
- high intratumor pressure –> dense tumor stroma
Goldie-Coldman Hypothesis
- likelihood that drug-resistant cancer cells are present at diagnosis
- suggests:
- multidrug treatment
- short dose tiem
- early in cancer is better
Chemotherapy Classes
- direct DNA damaging agents (cross linkers, alkylators, intercalators) –> S phase
- inhibitors of chromatin remodeling (topoisomerase I and II inhibitors) –> S phase
- inhibitors of DNA synthesis (pyridine analogs) –> S phase
- tubulin interactive drugs (microtubule stablizers/destabilizers) –> M phase
Direct DNA Damaging Agents; Cross-linkers-Cisplatin
- stable in aqueous environments with chlrodie
- binds DNA in cell and forms adducts (b/c of low chloride instability)
- cell cycle arrest and apoptosis
Resistance
Direct DNA Damaging Agents; Cross-linkers-Cisplatin
- decreased cellular drug uptake
- reactive platinum species bind to thiol containing proteins
- enhanced repair of DNA adducts
- tolerance of DNA adducts
Direct DNA Damaging Agents; Alkylating Agents
-Cyclophosphamide & Ifosfamide
- mustard derivatives
- pro-drugs –> cytotoxic after hydroxylation by cytochrome p450 and breakdown to phosphoramide mustard and acrolein
- phosphoramide mustard reacts with DNA
Resistance
Direct DNA Damaging Agents; Alkylating Agents
-Cyclophosphamide & Ifosfamide
- DNA repair enzymes
- decreased cellular permeability
- reaction of drug with thiols like glutathione
Inhibitors of chromatin remodeling-Topoisomerase II Inhibitors-Doxorubicin
- natural anthracylcine antibiotic
- enters nucleus and binds DNA –> intercalation of multiple molecules results in a “knot” topoisomerase cannot unwind –> inhibition
Inhibitors of chromatin remodeling-Topoisomerase I inhibitors-Topotecan & Irinotecan
- S-phase specific
- binds enzyme-DNA complex prevents re-ligation of single strand breaks
Resistance
Inhibitors of chromatin remodeling-Topoisomerase inhibitors
- P-glycoprotein
- membrane pumps
- detoxifciation with glutathione
- decreased expression/mutation of topoisomerase
- enhanced DNA repair
- decreased metabolic conversion of drug
Inhibitors of DNA synthesis- pyridine analogs
- 5FU –> competes with uridine for binding to TS (thymidylate synthase) –> thymidine not synthesized –> DNA replication stop –> S phase arrest
- methotrexate –> impairs production of dihydrofolate reductase –> no tetrahydfolic acid precursor for TS–> DNA replication stop –> S phase arrest
Resistance
Inhibitors of DNA synthesis-pyridine analogs-methotrexate
- decreased cellular transport
- cellular efflux pumps
- decreased polyglutamylation
- increased polyglutamate hydrolases
- increase in DHFR gene copy number
*
Tubulin interactive drugs-microtubule stabilizers-taxanes
- Paclitaxel –> binds B tubulin–> no depolymerization –> inhibition of DNA synthesis –> mitotic block at anaphase –> apoptosis
Tubulin interactive drugs-microtubule destabilizers-vincas
- prevent formation of microtubules
Resistance
Tubulin interactive drugs-microtubule stabilizers-taxanes-paclitaxel
- P-glycoprotein
- microtubule associated proteins (MAPS) which impair binding of taxanes to tubulin
Resistance
Tubulin interactive drugs-microtubule destabilizers-vincas
- Efflux by P-glycoprotein
- tubulin mutations
- altered expression of tubulin isoforms
Inhibition of angiogenesis
- Bevacizumab blocks VEGF–> no vascular proliferation,permeability, and reduced upregulation of antiapoptosis
- mTOR inhibitors –> block hypoxia inducible factors –> reduce VEGF production
- tk inhibitors –> block VEGF 1/2 receptors vascular endothelial cells
Anti-CTLA4 drug and mechanism
Ipulimumab: blocks CTLA4 –> upregulates T cell activation
metastatic melanoma
Anti-SERM (selective estrogen receptor modulator) drug and mechanism
Tamoxifen
breast cancer
Anti-CD20 drug and mechanism
Rituximab: targets mature B cells –> depletion and immune suppression
Anti-HER1/2 drug and mechanism
Trastuzumab: blocks epidermial growth factor receptors
breast cancer
Anti-c-abl/c-kit/tk inhibitor and mechanism
Imatinib/Gleevac: high specificity for BCR-ABK receptor –> arrest of growth and apoptosis
CML
anti-VEGF drug and mechanism
Bevacizumab: binds VEGF –> reduces angiogenesis
Stem cell classes
- totipotent = germ cells
- pluri = stem cells, induced
- uni/oligo = hematopoeitic
TPO mimetics
Romiplostim and Eltrombopag
- stimultae megakaryocyte proliferation and differentiation
Fanconi Anemia
- recessive xlinked disorder of DNA repair
- ID: pancytopenia, congenital abnormalities, MDS/AML, bm failure
- Dx: DEB/MMC cross link test
Dyskeratosis Congenita
- telomeric
- ID: pancytopenia, leukoplakia, bone marrow failure, nail dystrophy, pigmentation
Diamond Blackfan Anemia
- autosomal dominant ribosomopathy
- ID: red cell aplasia, congenital abnormalities
- Dx: red cell adenosine deaminase
How do we distinguish acquired from inherited bone marrow failure?
- no congenital abnormalities
- repsonsive to immunosuppression
- not heritable
- low risk of transformation
Hairy Cell Leukemia
- NHL B CD103/CD25/CD11c/ANXA1/Cyclin D1 (pl-binding protein)
- infiltration of spleen, bm, liver, but not lymph nodes
- ID: pancytopenia, splenomegaly, fried egg cytology
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Which HCLv have the worst prognosis?
those with IGHV4-34
What genetic lesion is implicated in HCL?
BRAF V600E-->MAP kinase pathway to cell proliferation
Main BRAF inhibitor
Vemurafenib