Gastrointestinal Stromal Tumors

1
Gastrointestinal Stromal Tumors
Sheng-wei Ye , M.D.Department of abdominal
surgery, Yunnan tumor hospital

• June 13, 2006

2
Case Report

• 74 yo woman presented with lower abdominal pain
  for 6 months
• She developed a fever and leukocytosis, but no
  wt. loss, night sweats
• Colonoscopy 6 wks prior to admission showed
  diverticular disease, no other abnormality.
• CT ABD / PEL 9x8 cm solid mass in pelvis

3
Case Report

• Exploratory laparotomy revealed a 8x7x6 cm solid
  mass arising from the wall of the small bowel,
  plus an intra-abdominal abcess. The mass was
  completely resected.

4
Case Report

• Path spindle cell morphology,
• IHC CD34 actin c-kit
• increased mitotic figures high grade
• gastrointestinal stromal tumor (GIST)
• Her post-operative course was complicated with
  DVT and PE
• CT at 3 months post-op showed no evidence of
  tumor, and she was doing well

5
GastroIntestinal Stromal Tumors (GIST)

• Definition
• Rare soft tissue tumor of the GI tract,
  mesentery, and omentum
• Histologic subtypes include spindle, epitheliod,
  mixed
• Express CD34, Actin, and recently recognized as
  almost uniformly c-KIT
• Normal Counterpart
• Interstitial cells of Cajal (ICC), a cell
  bridging smooth muscle and neuronal tissues of
  the autonomic system (similar phenotype)

Rossi et al. Int. J. Cancer 107171, 2003 Joensuu
et al Lancet Oncol 3655, 2002
6
Epidemiology

• 0.1-3 of all GI cancers
• Incidence 1-2/100,000 based on historical data
  (difficult to interpret due to changing
  diagnostic criteria in the past)
• Estimates now of 5000-6000/new cases per year in
  US with updated diagnostic criteria
• Tends to occur in middle aged persons with a
  slight male predilection
• Occur throughout the GI tract

7
Site of primary tumor

• Stomach (50-70),
• small intestine (20-30)
• colorectal (10-20)
• Esophagus 5
• Other e.g. mesentery, omentum (rare)

8
Clinical Presentation

• Symptoms depend on the site and size of the tumor
  
• Include
• Abdominal pain
• Dysphagia
• Gastrointestinal bleeding
• Symptoms of bowel obstruction
• Small tumors may be asymptomatic
• Primary tumor only (46), Metastatic disease (47)

Rossi et al. Int. J. Cancer 107171, 2003 Joensuu
et al Lancet Oncol 3655, 2002
9
Diagnosis

• Clinical Presentation
• Light microscopy in conjunction with
  Immuno-histochemistry

10
Immunohistochemistry

• Positive staining for CD117, a cell surface
  antigen on the extracellular domain of the KIT
  receptor
• Positivity alone without a typical morphological
  appearance may be a false positive
• lt 2 of tumors are negative for CD 117
• Such tumors are labeled Stromal cell neoplasm
  most consistent with GIST
• 60-70 of tumors are also positive for
• CD 34

11
Imatinib x 4 weeks
Before Treatment
KIT IHC
H E
Demetri et al NEJM 347472, 2002
12
Benign Vs Malignant

• Features favoring benign lesions in general like
• Size less than 5 cm
• Low number of mitosis per HPF
• No mucosal invasion
• Low cellularity
• Low markers of cell proliferation
• The above have shown to be associated with
  malignant behavior in some but not in other
  studies.
• With prolonged follow up any GIST has the
  potential to behave in a malignant fashion.
• 50 of primary localized tumors that are resected
  relapse after 5 years of follow up.

13
Malignant Versus Benign
Size Mitotic count
Very Low risk lt2 cm lt5/50 HPF
Low risk 2-5 cm lt5/50 HPF
Intermediate risk lt5 cm 5-10 cm 6-10/50 HPF lt5/50 HPF
High risk gt5 cm gt10 cm Any size gt5/50 HPF Any count gt10/50 HPF
Human pathology, Vol 33, May 2002
14
Prognostic Factors

• No uniform prognostic guidelines, poor Px
  associated with
• increasing tumor size
• metastatic disease at presentation
• high grade (high mitotic index)

15
Primary Treatment Surgery

• 67 primary tumors resectable,
• However, 40-90 recur (most often
  intra-abdominal, liver)

16
GIST Pre-Imatinib Outcomes

• All GIST
• 5 year survival 28-43
• Median survival 19 months
• Single primary tumor completely resected
• 5 year survival 50-65
• Medial survival 66 months
• Metastatic disease or recurrent disease
• Median survival 9-12 months
• Chemotherapy? not effective
• Phase III trial of doxorubicin dacarbazine
  (n118)
• RR 17 with CR (5) and PR/SD (12)
• Duration of response with PR/SD 6mo, CR 19mo
• Zalupski et al. JNCI 83926, 1991

Rossi et al. Int. J. Cancer 107171,
2003 DeMatteo et al. Ann. Surg. 23151, 2000
17
Disease specific survival and tumor size
Ann Surg 23151-57, 2000
18
History of GIST?

• Until the late1960s stromal tumors arising in
  the GI tract were referred to as smooth muscle
  neoplasms of the gastrointestinal tract.
• Immuno-histochemistry in the 1980s demonstrated
  that some of these tumors lacked features of
  smooth muscle differentiation, some had markers
  of neuronal differentiation and some had neither
  of the above markers.
• This led to Mazur and clark to coin the general
  term Gastrointestinal stromal tumors to
  collectively refer a group of mesenchymal tumors
  of neurogenic or myogenic differentiation.

19
History of GIST

• In the 1990s it was shown that a significant
  proportion (60-70)of tumors showed CD 34
  immunopositivity
• But schwann cell and true smooth muscle cell
  neoplasms were also positive
• Lots of confusion prevailed until late 1990,s

20
Discovery of Kit

• In 1986 a new acute transforming feline
  retrovirus, the Hardy-Zuckerman 4 feline sarcoma
  virus (HZ4-FeSV) was isolated from a feline
  fibrosarcoma.
• The viral genome of HZ4-FeSV contained a new
  oncogene that was designated v-kit
• C-kit is the cellular homologue of the oncogene
  v-kit
• It encodes a transmembrane tyrosine kinase
  receptor called kit.
• Nature 1988 Sep 1335(6185)88-9

21
What is Kit?

• Kit is a 145-KD glycoprotein
• The kit receptor can be detected by
  immuno-histochemical staining for CD117
• CD117 is an epitope on the extra-cellular domain
  of the Kit receptor
• Steel factor (SLF), also known as stem-cell
  factor, is the ligand for Kit
• Binding of SLF to Kit results in receptor
  homo-dimerization, activation of KIT tyrosine
  kinase activity, and resultant phosphorylation of
  a variety of substrates that serve as effectors
  of intracellular signal transduction.

22
Kit
Human pathology, Vol 33, May 2002
23
Kit and relationship to GIST

• SCF-KIT interaction has been shown to be
  essential for development of melanocytes,
  erythrocytes, germ cells, mast cells and ICCs
• Mice with mutations involving kit have cellular
  defects in hematopoiesis, melanogenesis and
  gametogenesis and also lack the network of
  interstitial cells of Cajal.
• In 1995 it was shown that the interstitial cells
  of Cajal express the Kit receptor
• Nature 1995 Jan 26373(6512)347-9

24
Kit and relationship to GIST

• Hirota et al investigated the mutational status
  of c-kit in mesenchymal tumors of the GI tract.
• They examined 49 mesenchymal tumors that were
  diagnosed as gastrointestinal stromal tumors
• 94 (46/49) of these expressed KIT.
• 82 (40/49) were CD34-positive
• 78 (38/49) were positive for both KIT and CD34
• Also demonstrated that ICC were positive for kit
  and CD 34.
• They also demonstrated that mutations of c-kit
  resulted in gain of function of the enzymatic
  activity of the KIT tyrosine kinase

25
Kit and GIST

• Mutations of several different exons of the c-kit
  gene (exon 11 and rarely, exons 9 and 13 )can
  cause constitutive activation of the tyrosine
  kinase function of c-kit.
• These mutations result in
• Auto-phosphorylation of c-kit
• Ligand-independent tyrosine kinase activity
• Uncontrolled cell proliferation
• Stimulation of downstream signaling pathways

26
KIT Tyrosine Kinase is Constitutively
Phosphorylated and Mutated in GIST

• KIT over-expressed in GIST (gt90) by IHC
• Sarloma-Rikala et al. Mod Pathol 11728, 1998
• Gain-of-function mutations in c-kit are present
  in GIST
• Hirota et al. Science 279577,1998
• Rubin Cancer Res 618118, 2001

27
Hirota et al. Science 279577,1998
28
KIT mutations in GIST
JM region in e11
Hirota et al. Science 279577,1998
29
KIT or KITD

mIL3R
KIT-plasmid
mIL3R
BAF/3 KIT or KITD
BAF/3
GIST mutations
GIST mutations
WT KIT
BAF/3
WT KIT
BAF/3
Hirota et al. Science 279577,1998
30
BAF/3 Expressing KIT with GIST Mutations Grow
Autonomously in Mice
GIST mutations
WT KIT
BAF/3
Hirota et al. Science 279577,1998
31

• 48 GIST evaluated
• ALL had constitutively phosphorylated KIT
• 92 (44) had KIT mutations
• Insertions, deletions, in frame mutations of
  exons 9, 11, 13, 17
• No correlation with traditional markers of
  malignancy or prognosis

Rubin Cancer Res 618118, 2001
32
Mutated Tyrosine Kinases in GIST PDGFRa

• Subset of GIST tumors without KIT mutations
  (KIT-WT)
• PDGFRa was constitutively P-lated in KIT-WT GIST
• 30 of KIT-WT GIST had PDGFRa mutations
• No GIST had both KIT and PDGFRa mutations

Heinrich et al Science 299708, 2003
33
Mutations in KIT and PDGFR in GIST
KIT (92 of GIST)
PDGFRa (30 of KIT-WT)
Ligand Binding
Ligand Binding
Dimerization
Dimerization
13
e9
Juxtamembrane
e11
71
Juxtamembrane
e12
28
TK1, ATP Binding
TK1, ATP Binding
e13
4
Kinase Insert
Kinase Insert
TK2, P-transferase
TK2, P-transferase
e18
71
4
e17
Mutations constitutive activation
MAPK, PI3K, STAT5, Jak2, Ras
Heinrich et al Science 299708, 2003
Rubin Cancer Res 618118, 2001 Hirota et al.
Science 279577,1998
34
Imatinib Mesylate is a small molecular inhibitor
designed against BCR-ABL, but also cross-reacts
to inhibit KIT and PDGFRa
35
Imatinib Mechanism
BCR-ABL or KIT or PDGFRa
BCR-ABL or KIT or PDGFRa
Signals for growth, survival
Adapted from Imatinib / CML Prescribing
Guidelines, Novartis
36
Preclinical experiments

• A C-kit expressing human myeloid leukemia cell
  line, M-07e,was treated with STI 571 before
  stimulation with Steel factor (SLF) and STI 571
  inhibited c-kit autophosphorylation.
• The activity of STI 571 in a human mast cell
  leukemia cell line (HMC-1), which had an
  activated mutant form of C-kit was tested. STI
  571 had a more potent inhibitory effect on the
  kinase activity of this mutant receptor than it
  did on ligand-dependent activation of the
  wild-type receptor.
• Heinrich Blood, Vol. 96 No. 3 (August 1), 2000
  pp. 925-932

37
Preclinical experiments

• A human GIST cell line, (GIST882) which expressed
  an activating KIT mutation (K642E) leading to
  constitutive tyrosine phosphorylation was tested
• Tyrosine phosphorylation was rapidly and
  completely abolished after incubating the cells
  with Imatinib.
• GIST882 cells evidenced decreased proliferation
  and the onset of apoptotic cell death after
  prolonged incubation with Imatinib
• Oncogene 2001205054-5058

38
First patient to be treated with Imatinib

• 54 year old female with metastatic GIST diagnosed
  in 1996
• Liver metastases and multiple small
  intra-abdominal metastases were excised in
  February 1998 and in September 1998
• Seven cycles of chemotherapy with doxorubicin,
  ifosfamide, and dacarbazine with no response
• In March 1999 had bowel obstruction and on
  laparotomy had diffuse intraabdominal mets.
• Received thalidomide and interferon with no
  response
• Treatment with 400 mg Imatinib once daily was
  started in March 2000.
• N. Engl. J. Med., 344 1052-1056, 2001

39
Imatinib in GIST
Demetri et al NEJM 347472, 2002
40
Imatinib Mesylate in GIST

• Open-label, randomized, Phase II (scaled up Ph
  I), multicenter trial
• 147 patients with advanced GIST (unresectable or
  metastatic)
• Prior therapy included surgery (98),
  chemotherapy (51), XRT (15)
• CD117 (KIT) positive tumors (did not look at
  mutation status)
• Randomized to 400 mg or 600 mg qD of Imatinib

Randomize
400 mg Daily
600 mg Daily
PD
PD
CR, PR, SD
CR, PR, SD
Stop Therapy
Continue 400 mg
600 mg Daily
Demetri et al NEJM 347472, 2002
41
Imatinib Mesylate in GIST
Demetri et al NEJM 347472, 2002
42
Imatinib Mesylate in GIST
(Progression free survival)
Historical Comparison Median survival 9-12
months!
Demetri et al NEJM 347472, 2002
43
Presentation
4 weeks
16 weeks
Demetri et al NEJM 347472, 2002
44
Imatinib x 4 weeks
Before Treatment
KIT IHC
H E
Demetri et al NEJM 347472, 2002
45
Case Report

• She did well for 9 months, but then developed
  recurrent abdominal pain

46
Case Report

• CT-biopsy of mass showed recurrent GIST
• Pt. treated with neo-adjuvant Imatinib 600 mg qD
• Stable disease, with mass decreasing from 10x10
  cm to 8x7cm

47
Case Report

• Stable disease with PET signal ablation after 3
  months of neo-adjuvant Imatinib
• Underwent her 2nd resection
• Continued on adjuvant Imatinib
• After 2-3 months, developed progressive edema and
  anasarca (grade 3) due to Imatinib
• Drug held, then later restarted at a lower dose,
  pt. continues to do well on 200mg qD

48
Is an Identified KIT or PDGFRa Mutation Requisite
to treat GIST with Imatinib?

• Imatinib is now a labeled treatment for GIST
• Studies have correlated response to Imatinib to
  the presence of KIT mutations, however, not
  absolute
• What about the minority of GIST tumors that do
  not have KIT or PDGFRa mutations? Should they be
  offered Imatinib?

49
Journal of Clinical Investigation 114379, 2004
50
New Trick for Imatinib? GISTs Lacking KIT/PDGFR
mutations respond to Imatinib (!?!)
Pt Age Site ( tumors) Response Duration (months)
1 50 Liver, Stomach CR 26
2 60 Liver PR 24
3 48 Lungs CR 26
4 25 Liver (3) SD 17
5 67 Liver (4) SD (3) PR (1) 7
6 18 Stomach SD 15

• Tested and Negative for all known mutations of
  KIT (e9, 11, 13, 17) and PDGFRa (e12, 14, 18)

J Clin Invest 114379, 2004 Extracted from
Supplemental Table 1
51
If Imatinib is not acting to inhibit a specific
KIT or PDGFRa gain-of-function mutation, how is
it working?Direct or Indirect Mechanism ?
52
Indirect Innate Immune Mechanism of Action of
Imatinib
Imatinib
NK
?
DC
X
KIT
IFNg
KILL
GIST
53
Imatinib boosts NK Cell Activation In Patients
with GIST

• Co-culture of pt. BM-derived DC and NK
• IFNg Measured in Supernatant
• Lines show data from serial pt. samples

J Clin Invest 114379, 2004
54
NK Cell Activation is Associated with Prolonged
Progression Free Survival in GIST Patients
Receiving Imatinib
N22
(After 2 months of Imatinib Therapy)
N21
J Clin Invest 114379, 2004
55
Lichenoid Dermatitis in Pt. on Imatinib DC / NK
Mediated?
mDC
NK
J Clin Invest 114379, 2004
56
What Other Scenarios Could this Innate Immune
Effect be Utilized?

• Any pt treated with Imatinib (e.g. CML, GIST,
  etc)
• Treatment failure an association with lack of
  innate immune effect?
• Does long term response correlate with innate
  immune activation?
• Are other malignancies that may be NK cell
  sensitive candidates for Imatinib trial?
• Malignant melanoma, renal cell carcinoma
• Myeloid leukemia after mismatched allogeneic SCT?
• Therapy during allogeneic SCT to boost innate
  immune recognition of leukemia?

57
An Open Mind About Targeted Therapies

• Targeted therapies are by definition engineered
  to mediate a desired effect
• As always, it is impossible to predict and
  control all of the biologic effects of a molecule
  in living organisms
• We must be open minded about unexpected
  biological effects of future targeted therapy