1. Axel Grothey Mayo Clinic College of Medicine Rochester, MN
The Continuation of Biologic Agents Beyond Progression: Does It Make Sense?
Axel Grothey
Mayo Clinic College of Medicine
Rochester, MN

2. Continuation of Chemotherapy Beyond Progression
FOLFOX  FOLFIRI Tournigand
FOLFIRI  FOLFOX Tournigand
LV5FU2  FOLFIRI FOCUS
LV5FU2  FOLFOX FOCUS
Irino  Irino + Cetuximab BOND, Saltz

3. Biologic Agents in Colorectal Cancer = Monoclonal Antibodies
Fab Fc
Murine Ab
“momab”
Chimeric
Mouse-Human Ab
“ximab”
Humanized Ab
“zumab”
Human Ab
“mumab”
EGFR
(17-1A)
Cetuximab
Matuzumab
Bevacizumab
Panitumumab
VEGF

4. Nomenclature of Monoclonal Antibodies
-mab monoclonal antibody
-mo-mab mouse mab
-xi-mab chimeric mab
-zu-mab humanized mab
-mu-mab human mab
-tu-xx-mab tumor-directed xx mab
-li-xx-mab immune-directed xx mab
-ci-xx-mab cardiovascular-directed xx mab
-vi-xx-mab virus-directed xx mab
Inf-li-xi-mab Beva-ci-zu-mab Ri-tu-xi-mab Pani-tu-mu-mab

5. mAbs Target Tumor Cell-Bound EGFR
Ligand
Extracellular
EGF-R
Ras
PI3K
Raf
Intracellular
Akt
MEK
MAPK
Cell survival
DNA
Cell Motility
Proliferation
Angiogenesis
Metastasis

6. Only a Subgroup of Patients Benefits from anti-EGFR mAbs
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
Weeks from Randomization 8 16 24 32 40 48 56
1.0
0.9
0.8
Cetuximab
Panitumumab
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0.0 3 6 9 12 15
MONTHS
Jonker et al., AACR 2007
Van Cutsem et al., JCO 2007

7. EGFR mAbs - Potential Mechanisms of Resistance (selected)
Activation of other RTK which bypass EGFR pathway
IGF-1R
HER-2
Constitutive activation of signaling pathways downstream of EGFR
Inactivation of PTEN
KRAS mutation
Mutated STATs
EGFR gene amplification
Overexpression of VEGF

8. KRAS Mutation Status Predictive of Response to Cetuximab?
30 patients with CRC on cetuximab
PR: 11/30 patients (37%)
KRAS mutation in
0/11 responders
13/19 non-responders (68%)
p=0.0003
Increased EGFR gene copy number in 10%
significantly associated with response (p=0.04)
16.3 mo
6.9 mo
Lievre et al. Cancer Res 2006

9. Rationale for Combining EGFR- and Angiogenesis- Inhibitors
EGFR Inhibitors
Angiogenesis Inhibitors
Tumor cell growth
Synthesis of angiogenic proteins
Response of endothelial cells to angiogenic proteins
Targets - - -
Angiogenic proteins
bFGF
VEGF
TGF-
Endothelial cells
Tumor
Herbst et al. J Clin Oncol. 2005;23:2544.

10. BOND-2 Trial - Efficacy (historic comparison with BOND-1)
+BEV
C225+CPT
N pts
111 40
218 41
Previous Oxaliplatin (%) 64 90 62 85
RR (%) 11 20 23 37
TTP (mos)
1.5
5.6
4.1
7.9
Med. OS (mos)
6.9
10.2
8.6
18.0
Saltz et al. ASCO 2005; Lenz et al. ASCO GI 2007

11. NCCTG First-line Randomized Phase II Trial (N0548) - Cetuximab Beyond PD
FOLFOX +
Bevacizumab
C225 +
Bevacizumab PD R
FOLFOX + C225
+ Bevacizumab
90 patients
Based on the impressive efficacy results of dual antibody combination as salvage therapy, we will explore this treatment option in the front-line setting in patients with metastatic CRC who are not considered candidates for a neoadjuvant approach.
The trial design was developed with the input of patient advocates and will use a combination of bevacizumab and cetuximab as initial therapy with close monitoring of the disease.
Upon progression, patients will be randomized to receive FOLFOX + bevacizumab plus/minus cetuximab.
The trial will have extensive translational components including angiogenesis markers and PET imaging.
Primary endpoint
PFS rate at 6 months (Goal >50% of patients)
Interim analysis after 45 pts
Secondary endpoints
Response rate
Safety
Angiogenesis markers
Imaging studies

12. Characteristics of Anti-EGFR vs Anti-VEGF Therapy
Anti-EGFR mAb
Anti-VEGF mAb
Single agent activity
In combination with chemo consistent increase in RR
Increased chemo- and radio-sensitivity
Resensitization of tumors to chemo (CPT11)
Minimal single agent activity
In combination with chemo consistent increase in PFS
Decrease in interstitial pressure, better delivery of chemo
“Normalization” of vasculature, better oxygenation
Main target: Tumor cells
- genetically instable -
Main target: Endothelial cells
- genetically stable -

13. Is There a Rationale to Continue Bevacizumab Beyond Progression?
Should bevacizumab be “herceptinized”?

14. Continuation of Bevacizumab Beyond Progression - PRO
Mechanism of action targets genetically stable (endothelial) cells
Decreased intratumoral interstitial pressure leads to higher concentrations of chemotherapeutic agents
Normalization of vasculature and better oxygenation
 Cytotoxic effects of all (?) chemotherapeutics, regardless of “line of therapy” enhanced

15. Dynamic Effects of Anti-VEGF Therapy on Tumor Vasculature
Early effects (days 2-5):
 Hypoxia /  Oxygenation
Tumor vessel pruning
Normal
Late effects (day 5):
inhibition of blood vessel growth
One hypothesis concerning the early effects of anti-VEGF therapy postulates that tumor vessel pruning and reversing abnormal, inefficient vasculature increase blood flow and, hence, delivery of chemotherapy to the tumor.
Normal blood vessels are regularly spaced based on the limitations of nutrient diffusion, whereas tumor vessels are chaotic and do not maintain features of normal branching hierarchy.
Anti-VEGF treatment (VEGFR-2 blockade with anti-VEGFR-2 mAb) greatly reduced tumor hypoxia, pruned immature vessels, and led to normalized vasculature during a 2- to 5-day “time window” after treatment initiation.
In this hypothesis, the late effects of anti-VEGF therapy render normalized vasculature inadequate for tumor growth.
This is 1 hypothesis, and may apply only in selected tumor types.
Anti-VEGFR
Anti-VEGFR
Tumor vasculature
Days 2-5: normalized
Inadequate for tumor growth
Winkler et al. Cancer Cell. 2004;6:553; Jain. Nat Med. 2003;9:685.
Jain RK. Molecular regulation of vessel maturation. Nature Med. 2003;9:
Winkler F, Kozin SV, Tong RT, et al. Kinetics of vascular normalization by VEGFR2 blockade governs brain tumor response to radiation: role of oxygenation, angiopoietin-1, and matrix metalloproteinases. Cancer Cell. 2004;6:

16. Effect of VEGF Inhibition on Vessel Density and Tumoral Chemotherapy Concentration20 15 10 5 *
Placebo
Anti-VEGF mAb †
This preclinical study assessed the effect of decreased microvessel density caused by VEGF inhibitors on delivery of concomitantly administered chemotherapy.
Immunosuppressed mice bearing colon adenocarcinoma, xenografts established using the HT29 colon cancer cell line, were treated with the anti-VEGF mAb A4.6.1 or placebo.
Irinotecan was administered to the mice 1 week later.
Tumors were cryogenically preserved and measured for irinotecan concentration.
As anticipated, there was a significant decrease in vascular density in anti-VEGF–treated tumors and a correlative increase in tumor perfusion.
The intratumoral concentration of the fluorescent dye, H33342, was 57% higher in the anti-VEGF–treated group compared with the control group.
A trend toward increased intratumoral irinotecan concentration was also observed in the anti-VEGF–treated tumors (P=0.09).
These data showed that tumor vascular function and tumor uptake of anticancer drugs improved with VEGF-blocking therapy.
Tumor irinotecan
concentration
(µg/g)
Tumor H33342
concentration
(100 ng/g)
*P<0.09 vs placebo. †P<0.05 vs placebo.
Wildiers et al. Br J Cancer. 2003;88:1979.
Wildiers et al. Br J Cancer. 2003;88:1979.

17. Continuation of Bevacizumab Beyond Progression - PRO
Mechanism of action targets genetically stable (endothelial) cells
Decreased intratumoral interstitial pressure leads to higher concentrations of chemotherapeutic agents
Normalization of vasculature and better oxygenation
 Cytotoxic effects of all (?) chemotherapeutics, regardless of “line of therapy” enhanced
In experimental models rapid regrowth of blood vessels after withdrawal of VEGF-inhibitors

18. Rapid Regrowth of Tumor Blood Vessels
Selective inhibition of VEGFR signaling by AG in RIP-Tag2 mouse tumors
Basement membrane sleeves
Mancuso et al. JCI 2006

19. Continuation of Bevacizumab Beyond Progression - CON
Potential alternate pathways to activate angiogenesis apart from VEGF
Ang-system, FGF, PDGF and others
“Co-option” - recruitment of previously established vessels
Vascular remodeling, pericyte activation

20. The Complex Process of Tumor Angiogenesis
Angiogenesis in tumor tissue is complex and includes molecular cross-talk between tumor cells, endothelial cells and, to a lesser extent, pericytes.
Pathologic intracellular signaling in tumor cells is mediated by
Growth factors and their receptors
Activation of Ras
Increased action of transcription factors Akt and Erk
Activation of genes regulated by hypoxia-inducible factor-1 (HIF-1)
Genes regulated by HIF-1 and overproduced by tumor cells include
VEGF
Cell survival factors
IL-8
bFGF
Ang-1 and Ang-2
These factors, particularly VEGF, bind to receptors on resident endothelial cells and induce cell migration, proliferation, permeability, and survival.

21. Pericytes Proliferate in Tumors Resuming Growth During Chronic VEGF Blockade
Control
AntiVEGF
PDGF
PDGFR
Green = SMA
(Pericytes)
Huang, J. et al. Mol Cancer Res 2004;2:36-42

22. Pericytes Proliferate in Tumors Resuming Growth During Chronic VEGF Blockade
Huang, J. et al. Mol Cancer Res 2004;2:36-42

23. Continuation of Bevacizumab Beyond Progression - CON
Potential alternate pathways to activate angiogenesis apart from VEGF
Ang-system, FGF, PDGF and others
“Co-option” - recruitment of previously established vessels
Vascular remodeling, pericyte activation
Endothelial cells are not necessarily genetically stable
Concept of cancer stem cells
BEV is not non-toxic (GIP, ATE, HTN, RPLS…)
Treatment alternatives exist most of the times
BEV is expensive

24. No prospectively randomized evaluation to date…
Clinical experience?
No prospectively randomized evaluation to date…

25. Ceiling Effect of PFS in First-Line CRC? Is BEV a Chemo-Equalizer?
PFS ( months)
sequential data

26. Efficacy: TREE-1 and TREE-2
FOLFOX
bFOL
CAPEOX
- BEV N=49
+ BEV N=71
- BEV N=50
+ BEV N=70
- BEV N=48
+ BEV N=72
Conf. RR (%)* 43 53 22 41 35 48
TTF (mo)
6.5
5.8
4.9
5.5
4.4
TTP (mo)
8.7
9.9
6.9
8.3
5.9
10.3
OS (mo)
19.2
26.0
17.9
20.7
17.2
27.0
*per protocol population
Hochster et al., ASCO 2006

27. If we cannot increase 1st line PFS, why does OS increase?
17 months
10 months
1st PFS
Post-1st PD Survival
OS Months
More effective use of all active agents?
Continuum of care…
Use of EGFR-mAbs?
Use of bevacizumab beyond PD?

28. BEV after 1st Progression in BEV-naïve Patients - E3200
FOLFOX + BEV (N=282)
FOLFOX (N=279)
BEV (N=228)
OS (mos)
12.9
10.8
10.2
PFS (mos)
7.3
4.7
2.7
RR (%)
22.7
8.6
3.3
p=0.0011
p=0.95
p<0.0001
p<0.0001
p<0.0001
p=N/A
B. Giantonio et al., JCO 2007

29. BRiTE Registry - Patients with Bevacizumab Beyond Progression (BBP)
Evaluable patients (n=1953)
BRiTE:
Total N=1953
1445 pts with 1st PD
932 deaths (1/21/07 cut-off)
Median follow-up 19.6 mo
1st Progression
(n=1445)
Physician decision - no randomization
No Post-PD Treatment (n=253)
No BBP (n=531)
BBP (n=642)
Grothey et al. ASCO 2007 #4036

30. BRiTE: Patient Outcome Based on Treatment Post 1st PD
No Post-PD Treatment (n=253)
No BBP (n=531)
BBP (n=642)
# of deaths (%)
168 (66%)
306 (58%)
260 (41%)
Median OS (mo)
12.6
19.9
31.8
1yr OS rate (%)
52.5
77.3
87.7
OS after 1st PD (mo)
3.6
9.5
19.2
Grothey et al. ASCO 2007 #4036

31. BRiTE: Kaplan-Meier Estimates Based on Treatment Post 1st PD
Survival after 1st PD
Overall survival
Grothey et al. ASCO 2007 #4036

32. Limitations of the Analysis
Patients were not randomized
Actual administration dates for BV and CT not collected; missing BV and CT stop dates
Potential bias that patients who survived longer had a greater potential to be treated with BBP
Possibility of unmeasured factors that may have biased these results

33. BRiTE: Conclusions
First suggestion of survival benefit associated with using BV beyond 1st PD (BBP)
Improved OS appears to be due to an increase in survival beyond 1st PD in patients treated with BBP
These findings support the evaluation of BBP in the prospective, randomized phase III Intergroup trial S0600/iBET

34. MCRC pretreated with FOLFOX + BEV or CAPOX + BEV or OPTIMOX + BEV
SWOG/NCCTG/NCIC 2nd-Line Trial: S0600/iBET (Intergroup BEV Continuation Trial)
To open 6/15/07
(FOLF)IRI/C225
MCRC pretreated with FOLFOX + BEV or CAPOX + BEV or OPTIMOX + BEV
(FOLF)IRI/C225
+ BEV 5 mg/kg
(FOLF)IRI/C225
+ BEV 10 mg/kg
N=1,260
Primary endpoint: OS (HR 1.30; 12  15.6 mos)
PI: Phil Gold