Lecture 3 - Kinases

Question 1

Molecular causes of cancer

Answer 1

signal transduction through kinases drives proliferation

Question 2

Kinases are one of the

Answer 2

largest classes of proteins encoded by the human genome

Question 3

Kinase inhibitors require

Answer 3

biomarkers to guide their application

Question 4

Genomic DNA from lung cancer biopsies are tested via

Answer 4

PCR for a particular mutation of EGFR
if positive these patients will go on anti-EGFR therapies

Question 5

Cell signaling is largely driven by

Answer 5

the transfer of phosphates
ATP is the major source of the phosphate group that is going to be transferred by a kinase to a target protein

Question 6

What is a common target of several kinases

Answer 6

tyrosine
serine, threonine, and lipids can also be phosphorylated
things with an OH group can be phosphorylated

Question 7

What balance the activity of kinases

Answer 7

phosphatases - by removing phosphates

Question 8

Cell signaling

Answer 8

ligand binds to tyrosine kinase –> receptors dimerize –> activated –> phosphorylates

Question 9

General structure of kinases

Answer 9

made up of N- and C-lobes connected by a hinge region
activation loop controls access to the active site

Question 10

Types of kinase inhibitors

Answer 10

type I, II, and III

Question 11

Type I inhibitors

Answer 11

bind to the active conformation of the kinase

Question 12

Type II inhibitors

Answer 12

bind and stabilize the inactive conformation of the kinase

Question 13

Type III inhibitors

Answer 13

occupy an allosteric pocket outside of the ATP-binding pocket

Question 14

Competitive inhibitors

Answer 14

bind kinase in a reversible fashion and therfore must compete with ATP for binding

Question 15

Covalent inhibitors

Answer 15

covalently bind with a reactive nucleophilic cysteine residue proximal to the ATP binding site, resulting in blockage of the ATP site and irreversible inhibition

Question 16

EGFR targeted kinase inhibitors

Answer 16

gefitinib, afatinib, neratinib, dacomitinib, erlotinib, osimertinib, lapatinib, tucatinib

Question 17

Patients with mutations in EGFR cause

Answer 17

the receptor to be constitutively activated
patients with these mutations show an enhanced response to EGFR inhibitors

Question 18

Epidermal growth factor receptor (EGFR)

Answer 18

EGFR functions through tyrosine kinase activity; EGFR signaling induces cell proliferation
EGFR is a protein on cells that helps them grow; EGFR is overexpressed in human cancer

Question 19

Gefitinib and erlotinib

Answer 19

erlotinib: small molecule reversible inhibitor of EGFR tyrosine kinase; competitively inhibits enzyme by binding to ATP binding site in kinase domain –> inhibition of kinase activity turns off signal to proliferate
approved for pts with metastatic NSCLC whose tumors have EGFR exon 19 or exon 21 mutations

Question 20

Afatinib

Answer 20

covalent inhibitor of all ErbB receptors
approved for EGFR mutant NSCLC with EGFR mutations
dacomitinib same thing

Question 21

What is the common SE of EGFR inhibitors

Answer 21

rash
if rash is present, more likely to respond well to inhibitor

Question 22

What causes resistance to geftinib

Answer 22

T790M

Question 23

What inhibitor works with the T790M mutation

Answer 23

osimertinib - covalent kinase inhibitor
bind in site with methionine, can inhibit mutant version

Question 24

Lapatinib

Answer 24

small molecule tyrosine kinase inhibitor that blocks HER2 and EGFR signaling; EGFR forms a hetrodimer with HER2, HER2 is amplified in breast cancer
selective for HER2+ breast cancer
reversible inhibitor of EGFR and HER2
watch for sx of CHF

Question 25

Tucatinib

Answer 25

small molecule tyrosine kinase inhibitor that preferentially binds HER2
selective for tx of HER2+ breast cancer
reduced AEs compared to others, no rash SE

Question 26

FLT3 mutations in acute myeloid leukemia

Answer 26

FLT3 mutation increases dimerization of receptors
either an internal tandem duplication or activating mutation in tyrosine kinase domain
FLT3 ligand is a cytokine receptor important for hematopoietic cell survival + proliferation
mutations lead to increased proliferation and decreased apoptosis

Question 27

FLT3 inhibitors

Answer 27

1st gen: midostaurin - broad kinase inhibitor (more toxic)
2nd gen: crenolanib - more specific
type II inhibitors: quizartinib - specific for ITD mutations

Question 28

Chromosomal translocations

Answer 28

philadelphia chromosome (Ph1) is the prototype chromosomal translocation
formed by joining the 5’ portion of the Bcr gene with teh 3’ portion of the Abl gene –> Bcr-Abl –> transcribed into mRNA –> translated into unique protein not found in normal cells
Ph1 chromosome in 95% of chronic myeloid leukemia

Question 29

Bcr-Abl drives

Answer 29

several proliferation pathways
acts as a kinase that is overexpressed to then drive cell proliferation

Question 30

Imatinib

Answer 30

the Abl protein is a tyrosine kinase; the kinase activity of the Bcr-Abl chimeric protein is constitutively active, resulting in malignancy
imatinib is a type II small molecule inhibitor of the Abl tyrosine kinase –> results in reduced proliferation and enhanced apoptotic cell death in CML and GIST
indication for CML
resistnace is a battle because pts need to be on Abl inhibitors for life

Question 31

Ponatinib

Answer 31

BCR-Abl inhibitor
effective against all major mutant forms of BCR-Abl
inhibits gatekeeper mutation T3151 that is resistant to all other BCR-Abl compounds

Question 32

________ is a significant driver event in lung cancer

Answer 32

EML4-ALK translocation

Question 33

EML4-ALK translocation

Answer 33

wild type ALK is a transmembrane receptor tyrosine kinase similar to EGFR
when ALK is inappropriately fused to ELM4, it becomes cytoplasmic and constitutively active –> proliferation, metastatis, anti-apoptosis

Question 34

Alectinib

Answer 34

more specific inhibitor of ALK
inhibits tyrosine kinase ALK
requires companion diagnostic test for fusion gene
indicated for ALK-positive and NSCLC

Question 35

Brigatinib

Answer 35

approved for NSCLC that have ALK mutations

Question 36

BRAF mutations in melanoma

Answer 36

lead to increase in cell proliferation and survival

Question 37

Dabrafenib

Answer 37

2nd gen BRAF-V600 inhibitor
used in combo with trametinib for treating BRAF V600E/K-mutant metastatic melanoma
colorectal cancer does not respond to this drug
also for NSCLC positive for BRAF-600 mutations

Question 38

Trametinib

Answer 38

inhibits kinase activity of MEK1 and MEK2
allosteric inhibitor
not indicated for pts who have received prior BRAF inhibitor therapy
AE: rash

Question 39

Bruton’s tyrosine kinase in B-cell malignancies

Answer 39

BTK is important for normal B cell activity and B cell tumor growth

Question 40

Ibrutinib

Answer 40

covalent inhibitor of BTK
used in MCL and CLL

Question 41

Acalabrutinib

Answer 41

2nd gen covalent BTK inhibitor
also targets Cys481
more potent and selective than ibrutinib
for B-cell lymphoma

Question 42

Rapamycin analogues

Answer 42

rapamycin also known as sirolimus
inhibit function of mammalian target of rapamycin (mTOR); mTOR is a serine threonine kinase
inhibits immune response by blocking IL-2 signaling transduction

Question 43

Everolimus

Answer 43

approved for renal carcinoma
only inhibits mTORC1 and not mTORC2 which can lead to feedback activation of Akt
involved more in metabolism and apoptosis

Question 44

What is a major problem with kinase inhibitors

Answer 44

resistance
kinase inhibitors only keep everything in remission, once you stop them, it comes back
goals of these therapies is to decrease the use of toxic chemotherapies

Question 45

Prognostic molecular pathology

Answer 45

how will patients respond
trying to find markers of response