aga/asco/astro/sso gastrointestinal cancers symposium orlando, fl january 26, 2008
DESCRIPTION
Circulating tumor cells: are they predictive markers?. AGA/ASCO/ASTRO/SSO Gastrointestinal Cancers Symposium Orlando, FL January 26, 2008. Neal J. Meropol, M.D. Fox Chase Cancer Center. “Predictive” vs. “Prognostic”. Predictive : explains variability in response to treatment - PowerPoint PPT PresentationTRANSCRIPT
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AGA/ASCO/ASTRO/SSOGastrointestinal Cancers Symposium
Orlando, FLJanuary 26, 2008
Circulating tumor cells: are they predictive markers?
Neal J. Meropol, M.D.Fox Chase Cancer Center
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“Predictive” vs. “Prognostic”
• Predictive: explains variability in response to treatment
– Traditional application before treatment
• Prognostic: explains variability irrespective of treatment
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Natural History of Circulating Tumor Cells
Paterlini-Brechot and Benali, Cancer Letters, 2007
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Potential advantages of circulating tumor cells (CTCs) compared to
other blood markers
• Representative of tumor access to circulation• Permits multiple simultaneous analyses
– Enumerate, phenotype, gene expression• Cytopathology• in vivo pharmacodynamic assessment, gene
expression profiling• Sensitivity/Specificity
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Why Study CTCs?
• Prognosis• Monitor disease course
– Minimal residual disease– Early relapse– Response to therapy
• Treatment selection• Drug development (pharmacodynamics)
– Target acquisition– Down stream effects
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Methods for CTC Detection
• Density gradient• Immunomagnetic separation (beads, ferrofluid)• Size-based filtration
Count
Cytopathology
RT-PCR
Genotyping20%-70% of patients with colorectal cancer have
detectable CTCs
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Immunomagnetic Separation
Magnetic Incubations
-
7.5 ml Blood + 6.5mL Buffer
PlasmaAspiration & Addition of
EPCAM Ferrofluid
Station 1 Stations2 & 3
Primary Magnetic
Separation & Resuspension
Station 4
-
Addition of Cytokeratin-PECD45-APC, &
DAPI
Station 5
Centrifuge
Place on Instrument
Described in: WJ Allard et al, Clin Cancer Res 10: 6897-6904, 2004
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Immunomagnetic Separation
Stations 6,7, & 8 Station 9b
Staining Incubation, Magnetic Wash &
Free Particle Removal
Final Resuspension
Station 9a Image Gallery
Automatic Transfer of Sample for Fluorescent
Image Analysis
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Characterization of CTCs by Flow Cytometry
SJ Cohen et al. Clin Colorectal Cancer, 2006
CD45-,CK+
CD45-,CK+,EGFR+
CD45+
beads
beads
CD45 PerCP
CD45 PerCPEGFR APC
Forward Light ScatterC
ytok
era
tinP
EO
rtho
gona
l Lig
ht S
catte
r
Cyt
oker
atin
PE
Nuc
leic
aci
d dy
e
CD45-,CK+
CD45-,CK+,EGFR+
CD45+
beads
beads
CD45 PerCP
CD45 PerCPEGFR APC
Forward Light ScatterC
ytok
era
tinP
EO
rtho
gona
l Lig
ht S
catte
r
Cyt
oker
atin
PE
Nuc
leic
aci
d dy
e
CTC, green and redEGFR+, redWBC, blueBeads, yellow
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N. J. Meropol, S. J. Cohen, N. Iannotti, B. H. Saidman, K. D. Sabbath, M. C. Miller, G. V. Doyle, H. Tissing, L. W.M.M. Terstappen, C.J.A. Punt
Fox Chase Cancer Center, Philadelphia, PA; Hematology Oncology Associates, Port St. Lucie, FL; Medical Oncology Associates, Kingston, PA;
Medical Oncology and Hematology, PC, Waterbury, CT; Immunicon Corporation, Huntingdon Valley, PA; Radboud University Medical Center,
Nijmegen, The Netherlands
Circulating tumor cells (CTC) predict progression free (PFS) and overall
survival (OS) in patients with metastatic colorectal cancer
ASCO 2007
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Objectives and Eligibility
Overall Objective
To determine the association between circulating tumor cell number and clinical outcomes in patients with metastatic colorectal cancer
EligibilityAdults with measurable metastatic colorectal cancer, initiating first-, second-, or third-line therapy
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Methods
• Multicenter international study• Radiographic tumor measurement at baseline
and every 6-12 weeks after treatment initiation (RECIST criteria)
• Peripheral blood was collected for CTC enumeration at baseline and subsequently at 1-2, 3-5, 6-12, and 13-20 weeks after treatment initiation
• Blood mailed overnight at room temperature, and processed at 1 of 4 laboratories within 96 hours
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11%12%13%14%16%18%21%26%33%47%53%0
2
4
6
8
10
12
14
16
18
20
22
24
26
0 >= 1 >= 2 >= 3 >= 4 >= 5 >= 6 >= 7 >= 8 >= 9 >= 10
CTC / 7.5mL of Blood (Baseline Draw)
Med
ian
OS
fro
m B
asel
ine
(Mo
nth
s) Median OS for Patients with Metastatic Colorectal Cancer Based Upon number of CTC
Prior to the Initiation of Therapy (N=413)
ASCO 2007
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Baseline CTC: Progression Free Survival%
Pro
gre
ssio
n F
ree
Time from Baseline Blood Draw (Months)0 2 4 6 8 10 12 14 16 18 22 24 26 28 30
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
20
P = 0.0002
CTC/7.5 mL Median in Months(95% CI)
<3 CTCs 7.9 (7.0 - 8.6)≥3 CTCs 4.5 (3.7 - 6.3)
<3 CTCs≥3 CTCs
305108
269 84
229 60
187 42
138 28
8816
44 8
32 3
20 2
15 2
81
60
30
00
00
00
ASCO 2007
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Baseline CTC: Overall Survival%
Su
rviv
al
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
Time from Baseline Blood Draw (Months)0 2 4 6 8 10 12 14 16 18 22 24 26 28 3020
<3 CTC≥3 CTC
305108
289102
276 86
252 66
227 49
180 36
134 24
107 13
7812
6011
43 7
32 4
22 2
11 1
41
20
CTC/7.5 mL Median in Months (95% CI)
<3 CTC 18.5 (15.5 - 21.2) ≥3 CTC 9.4 (7.5 - 11.6)
P < 0.0001
ASCO 2007
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CTC During Treatment: PFS%
Pro
bab
ility
of
Pro
gre
ssio
n F
ree
Su
rviv
al
Time from Blood Draw (Months)0 2 4 6 8 10 12 14 16 18 22 24 26 28 30
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
20
N Median PFS in Months (95% CI)
<3 CTC ≥3 CTC1-2 wks 315 7.3 (6.5 - 8.1) 3.8 (1.9 - 5.1)3-5 wks 329 6.8 (6.1 - 7.6) 1.9 (1.2 - 4.4)6-12 wks 284 6.5 (5.8 - 7.7) 2.0 (0.5 - 2.5)
P < 0.0001 at each timepoint
ASCO 2007
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CTC During Treatment: Overall Survival%
Pro
bab
ilit
y o
f S
urv
ival
Time from Blood Draw (Months)0 2 4 6 8 10 12 14 16 18 22 24 26 28 30
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
20
Median OS in Months (95% CI)
N <3 CTC ≥3 CTC1-2 wks 357 15.7 (14.3 - 18.4) 6.1 (4.9 - 8.9)3-5 wks 333 16.4 (14.1 - 18.3) 4.4 (2.6 - 8.7)6-12 wks 310 15.8 (13.8 - 19.2) 3.3 (1.8 - 5.6)
P < 0.0001 at each timepoint
ASCO 2007
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Predictors of PFS and OS:Multivariable Model – Baseline (N=373)
Variable PFS OS
HR P HR P
CTC number
<3 vs. >3 1.8 0.000 2.4 0.000
Line of therapy
1st vs. 2nd vs. 3rd
1.6 0.000 1.4 0.007
Age <65 vs. >65
1.5 0.001 1.9 0.000
PS 0 vs. 1 vs. 2
1.2 0.084 1.5 0.001
ASCO 2007
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Predictors of PFS and OS:Multivariable Model – 3-5 Weeks (N=302)
Variable PFS OS
HR P HR P
CTC number
<3 vs. >3 2.2 0.000 4.5 0.000
Line of therapy
1st vs. 2nd vs. 3rd
1.7 0.000 1.7 0.001
Age <65 vs. >65
1.6 0.000 2.1 0.000
PS 0 vs. 1 vs. 2
1.2 0.109 1.3 0.032
ASCO 2007
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Circulating Tumor Cells at Time of 1st Followup Image Add Prognostic Information
%P
rob
abil
ity
of
Su
rviv
al
Time from Baseline Blood Draw (Months)0 2 4 6 8 10 12 14 16 18 22 24 26 28 30
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
20
CTC Response N OS in Months(95% CI)
<3 CTC S/PR/CR 271 18.8 (17.0 - 25.1)<3 CTC PD/Death 64 8.3 (5.8 - 11.2)>3 CTC S/PR/CR 13 7.1 (5.4 - 10.8)>3 CTC PD/Death 16 3.1 (2.0 - 4.4)
vs. P < 0.0001
ASCO 2007
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Circulating Tumor Cells at Time of 1st Followup Image Add Prognostic Information
%P
rob
abil
ity
of
Su
rviv
al
Time from Baseline Blood Draw (Months)0 2 4 6 8 10 12 14 16 18 22 24 26 28 30
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
20
CTC Response N OS in Months(95% CI)
<3 CTC S/PR/CR 271 18.8 (17.0 - 25.1)<3 CTC PD/Death 64 8.3 (5.8 - 11.2)>3 CTC S/PR/CR 13 7.1 (5.4 - 10.8)>3 CTC PD/Death 16 3.1 (2.0 - 4.4)
vs. P = 0.0001
ASCO 2007
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Circulating Tumor Cells at Time of 1st Followup Image Add Prognostic Information
%P
rob
abil
ity
of
Su
rviv
al
Time from Baseline Blood Draw (Months)0 2 4 6 8 10 12 14 16 18 22 24 26 28 30
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
20
CTC Response N OS in Months(95% CI)
<3 CTC S/PR/CR 271 18.8 (17.0 - 25.1)<3 CTC PD/Death 64 8.3 (5.8 - 11.2)>3 CTC S/PR/CR 13 7.1 (5.4 - 10.8)>3 CTC PD/Death 16 3.1 (2.0 - 4.4)
ASCO 2007
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Decrease in CTC at 3-5 Weeks is Associated with Improved PFS in Patients with > 3 CTC at Baseline
% P
rob
abil
ity
of
Pro
gre
ssio
n F
ree
Su
rviv
al
Time from 3-5 Week Blood Draw (Months)0 2 4 6 8 10 12 14 16 18 22 24 26 28 30
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
20
Baseline 3-5 wks N Med PFS(95% CI)
≥3 CTC <3 CTC 52 6.2 (4.6 - 7.0)≥3 CTC ≥3 CTC 28 1.6 (1.2 - 2.7)
P = 0.02
ASCO 2007
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CTC Association with PFS and OS by Lines of Therapy
0.00
0.10
0.20
0.30
0.40
0.50
0.60
0.70
0.80
0.90
1.00
Pro
ba
bilit
y o
f P
rog
ress
ion
-Fre
e S
urv
iva
l
0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30Time from Baseline Blood Draw in Months
<3 CTC
>=3 CTC
1st Line Therapy mCRC Patients (N=296)
0.00
0.10
0.20
0.30
0.40
0.50
0.60
0.70
0.80
0.90
1.00
Pro
ba
bilit
y o
f P
rog
ress
ion
-Fre
e S
urv
iva
l
0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30Time from Baseline Blood Draw in Months
<3 CTC
>=3 CTC
2nd & 3rd Line Therapy mCRC Patients (N=117)
0.00
0.10
0.20
0.30
0.40
0.50
0.60
0.70
0.80
0.90
1.00
Pro
ba
bilit
y o
f S
urv
ival
0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30Time from Baseline Blood Draw in Months
<3 CTC
>=3 CTC
1st Line Therapy mCRC Patients (N=296)
0.00
0.10
0.20
0.30
0.40
0.50
0.60
0.70
0.80
0.90
1.00
Pro
ba
bilit
y o
f S
urv
ival
0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30Time from Baseline Blood Draw in Months
<3 CTC
>=3 CTC
2nd & 3rd Line Therapy mCRC Patients (N=117)
Cohen et al. AGA/ASCO/ASTRO/SSO GI Cancers Symposium, 2008
1st line
2nd line
PFS OS
HR=1.44 (1.04-1.98)
HR=2.22 (1.49-3.30)
HR=1.90 (1.26-2.85)
HR=2.98 (1.85-4.77)
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Conclusions
• In patients with metastatic colorectal cancer, CTC number before and after initiation of treatment is a significant independent predictor of progression free survival and overall survival
• CTC enumeration is complementary to imaging, and may provide early evidence of treatment success or failure
• Further research is required to determine whether change in therapy based upon elevated CTC number at early followup will improve patient outcomes
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Are CTCs Predictive Markers?
Maybe
• Traditional application before treatment– no data yet regarding role of
phenotyping/genotyping CTCs and response to therapy
• Alternative application early after treatment initiation– suggestive evidence that CTCs indicate
resistance to treatment
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Clinical validation study design requirements
• Standardized assay platform for clinical decision making
• Prospective randomized trial– archival well-annotated clinical specimens
do not exist• Randomized population of adequate size to
answer clinical question– Requires previous validation with assay
platform
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Metastatic disease study design:early change in therapy
Begin Treatment A
Assess at 1-3 weeks
Favorable CTCs?
Continue Treatment A
Yes*
Continue Treatment A
Change to Treatment B
R
No
*assumes that continuation of Treatment
A is best in Favorable CTC group
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Metastatic disease study design:selection of initial therapy
Favorable CTCs?
Standard initial therapy
Yes*
Standard initial therapy
More aggressive initial therapy
R
No
*assumes that standard therapy is “best” in
Favorable CTC group
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Surveillance study design 1: randomize early
Resected patients at risk for
recurrence
Routine surveillance
Routine surveillance +
CTC evaluation, with aggressive intervention if
CTC “recurrence”
R
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Surveillance study design 2: randomize later
Resected patients at risk for recurrence
Routine surveillance
plus CTC evaluation
CTC “Recurrence”
Continue routine surveillance
Aggressive intervention
R
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Many Questions Remain
• What are “circulating tumor cells”?• Are CTCs the same as in situ cancer?• How does cell separation process affect
gene expression?• How can CTCs be used in the drug
development process?• How can CTCs be integrated into routine
patient care?
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The End