1. EGFR, A Mutation &
Gefitinib
By: John Leonard
RBIF 102 Genomics and
Genetics

2. Introduction
The topic of this presentation is the EGFR gene and how a
mutation can help identify a palliative treatment:
 Epidermal Growth Factor Receptor
 Signaling Pathway
 The Gene EGFR
 Hallmarks of Cancer
 The L858R Mutation
 Gefitinib
 The Gefitinib Test
RasTop rendering of 1M17.pdb

3. Epidermal Growth Factor Receptor
The Epidermal Growth Factor Receptor; EGFR, ErbB-1,
HER1 depending on the literature:
 Member of the ErbB family of receptors, a subfamily of
the epidermal growth factor family (EGF-family) of
extracellular protein ligands.
 First cell surface signaling protein to be characterized by
molecular genetic methods.
 Is a Tyrosine Kinases (TK) protein and as such regulate
signaling pathways that control critical cellular activities.
 Plays an important role in carcinogenesis and is
therefore a target for cancer therapy.

4. EGFR Signaling Pathway
Upon activation, EGFR
undergoes
transformation and
forms an active homo-
or heterodimer, which
will initiate a distinct
signaling pathway
resulting in
autophosphorylation,
which in turn initiates a
downstream cascade of
events culminating in
cellular responses; such
as cell proliferation or
apoptosis. http://www.biooncology.com/

5. The Gene EGFR
EGFR/1956 found on chromosome 7 (7p12), all EGFR
family members are characterized by a modular structure,
with a highly conserved Tyrosine Kinase (TK) domain.
The TK domain contains an Adenosine Triphosphate (ATP)
binding region; ATP is referred to as the "molecular
currency“.

6. The Gene EGFR
Distribution of protein TK genes in the human genome (G-banded chromosome
ideograms)
The protein tyrosine kinase family of the human genome, Oncogene, 2000

7. The Hallmarks of Cancer
From a paper entitled The
Hallmarks of Cancer:
 Cancer cells have defects in
regulatory circuits that govern
normal cell proliferation.
 Cancer cells manifest six
alterations in cell physiology,
acting to breach the cell’s
anticancer defense mechanism.
 The evidence is mounting that
resistance toward apoptosis is a
hallmark of most, if not all types
of cancer. The Hallmarks of Cancer. Douglas Hanahan &
Robert A. Weinberg

8. The Hallmarks of Cancer
Elevated expression and/or amplification of EGFR have
been found in a variety of human cancers.
The epidermal growth factor receptor family as a central element for cellular signal transduction and
diversification, Endocrine-Related Cancer (2001)

9. The L858R Mutation
The L858R substitution/point mutation:
 A SNP, T>G which resulted in a modification of an amino
acid from Leucine (hydrophobic/small) to Arginine
(hydrophilic/large).
 It is the most common point mutation within EGFR.
 Non-Small Cell Lung Cancer (NSCLC) patients with the
L858R mutation have been found to be responsive to
treatment by selective inhibits, such as Gefitinib.
Lung cancer accounts for 1 in every 3 cancer deaths and an average of 439
people every day from lung cancer.

10. The L858R Mutation
L858R located in a mutation “hotspot” adjacent to a highly
conserved region around the ATP binding cleft; T790M.

11. The L858R Mutation
A study published in the Journal of the National Cancer
Institute, analyzed 134 mutations detected in the TK
domain of EGFR, identified 28 distinct mutations of three
different types, all centered around the ATP binding cleft.
Clinical and Biological Features Associated with Epidermal Growth Factor Receptor Gene Mutations in Lung Cancers,
Journal of the National Cancer Institute, March 2, 2005

12. The L858R Mutation
Mutations around the ATP-binding site leading to a structural
change in the protein structure, that in turn affect
functions.
“Mutation increases the sensitivity of the
tumor to inhibitors of EGFR, most likely
by repositioning critical residues
surrounding the ATP-binding cleft of the
tyrosine kinase domain of the receptor,
thereby stabilizing their interactions with
both ATP and its competitive inhibitors.”
EGFR Mutation and Resistance of Non–Small-Cell Lung Cancer to
Gefitinib, The New England Journal of Medicine, February 14, 2005

13. Gefitinib
Gefitinib (originally coded ZD1839) is marketed by
AstraZeneca and Teva under the trade name Iressa:
 Gefitinib is a TK/ATP-competitive inhibitor, which binds to
the ATP-binding site and inhibits kinase activity.
 From Endocrine-Related Cancer, 2001 - “Another
promising EGFR inhibitor, ZD-1839, which shows an
antiproliferative effect in ovarian, breast and colon cancer
cells is under clinical development”
 Another ATP-competitive inhibitor marketed by
Genentech and OSI Pharmaceuticals is Erlotinib.

14. Gefitinib
To-date no crystal structure of the
Gefitinib complex has been
published, a model of this complex
suggested that it has a
conformation similar to Erlotinib.
ErlotinibGefitinib
http://www.rcsb.org/

15. The Gefitinib Test
Gefitinib has had an interesting journey:
 In 2004 AstraZeneca advised the Food and Drug Administration
(FDA) that large scale studied of Gefitinib failed to demonstrate
any survival advantages in treatment of NSCLC tumors.
 In December 2006, Genzyme Corporation announced that it
would make available a laboratory test to identify patients that
would respond to treatment by Gefitinib and Erlotinib.
 The hope is that this test will help Gefitinib and Erlotinib win
regulatory approval as an initial therapy. Currently Gefitinib and
Erlotinib is only used for patients that have failed one or more
chemotherapy regimens.
Is this a step towards personalized medicine?

16. References
 http://www.biooncology.com/
 http://www.ebi.ac.uk/
 http://www.medicalnewstoday.com/
 http://www.lungcanceralliance.org/
 http://www.rcsb.org/pdb/
 The Hallmarks of Cancer, Douglas Hanahan & Robert A. Weinberg, Cell, January 7, 2000
 EGFR Mutation and Resistance of Non–Small-Cell Lung Cancer to Gefitinib, Susumu Kobayashi,
M.D., Ph.D., Titus J. Boggon, Ph.D., Tajhal Dayaram, B.A., Pasi A. Jänne, M.D., Ph.D., Olivier
Kocher, M.D., Ph.D., Matthew Meyerson, M.D., Ph.D., Bruce E. Johnson, M.D., Michael J. Eck,
M.D., Ph.D., Daniel G. Tenen, M.D., and Balázs Halmos, M.D., The New England Journal of
Medicine, February 14, 2005
 EGF receptor gene mutations are common in lung cancers from ‘‘never smokers’’ and are
associated with sensitivity of tumors to gefitinib and erlotinib, William Pao, Vincent Miller,
Maureen Zakowski, Jennifer Doherty, Katerina Politi, Inderpal Sarkaria, Bhuvanesh Singh, Robert
Heelan, Valerie Rusch, Lucinda Fulton, Elaine Mardis, Doris Kupfer, Richard Wilson, Mark Kris &
Harold Varmus, PNAS, September 7, 2004
 The protein tyrosine kinase family of the human genome, Dan R Robinson, Yi-Mi Wu & Su-Fang
Lin, Oncogene, 2000
 The epidermal growth factor receptor family as a central element for cellular signal transduction
and diversification, N Prenzel, O M Fischer, S Streit, S Hart & A Ullrich, Endocrine-Related
Cancer (2001)
 Clinical and Biological Features Associated with Epidermal Growth Factor Receptor Gene
Mutations in Lung Cancers, Hisayuki Shigematsu, Li Lin, Takao Takahashi, Masaharu Nomura,
Makoto Suzuki, Ignacio I. Wistuba, Kwun M. Fong, Huei Lee, Shinichi Toyooka, Nobuyoshi
Shimizu, Takehiko Fujisawa, Ziding Feng, Jack A. Roth, Joachim Herz, John D. Minna & Adi F.
Gazdar, Journal of the National Cancer Institute, March 2, 2005

17. Thank You and Questions
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