Loading in 2 Seconds...
Loading in 2 Seconds...
Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.
Antiangiogenics as Chemosensitizers:Out of the Frying Pan into the Fire?Dr. Urban Emmenegger
Potential Conflict of Interest • Consultant / 2008 – • Amgen • Research Grant – Consultant / 2007 – • Novartis • Research Grant / 2007 – • Wyeth
Montreal March 27 & 28, 2009 1st Quebec Conference on Therapeutic Resistance in Cancer Antiangiogenics as Chemosensitizers: Out of the Frying Pan into the Fire? Urban Emmenegger, MD Clinician-Scientist Sunnybrook Odette Cancer Centre & Research Institute Sunnybrook Health Sciences Centre Department of Medicine, University of Toronto 2075 Bayview Avenue, Toronto/ON M4N 3M5, Canadaurban.email@example.com
Disclosure Consulting Fees: Amgen, Novartis Research Funding: Novartis, Wyeth
Acknowledgements Sunnybrook Research Institute Annabelle Chow Bob Kerbel William Cruz John Ebos Chris Folkins Giulio Francia Kae Hashimoto Christina Lee Shan Man Tony Mutsaers Yuval Shaked Terence Tang Ping Xu D. Dumont M. Julius Sunnybrook Odette Cancer Centre Scott Berry Edward Chow Yoo-Joung Ko Linda Rabeneck Maureen Trudeau University of Pisa, Pisa/Italy Guido Bocci
Objectives • To review basic principles of tumor angiogenesis and antiangiogenic therapies. • To discuss the rationale for combining chemotherapy with antiangiogenic agents as a means to overcome/delay resistance. 3) To identify challenges of this approach.
Hippocrates… noticed that blood vessels around a malignant tumor looked like the claws of a crab. He named the disease karkinos (the Greek name for crab) … (http://medicineworld.org/cancer/history.html)
TAF inhibition reverses this process 3 1 2 Tumor angiogenesis: therapeutic implicationsFolkman J. N Engl J Med. 1971;285(21):1182-6
Local (sprouting) angiogenesis Sex hormones FGFs Thrombospondin-1/2 Interferon-α PEDF Angiostatin Endostatin Vasostatin Tumstatin Canstatin Arresten … IL-8 PDGFs VEGF-C VEGF-B PlGF VEGF-D EGF VEGF-A angiogenesis angiogenesis angiogenesis angiogenesis angiogenesis
The VEGF Family And Its Receptors PlGF VEGF-A* VEGF-B VEGF-C VEGF-D 206 189 165 121 VEGFR-2 (Flk-1/KDR) VEGFR-3 (Flt-4) VEGFR-1 (Flt-1) Angiogenesis Angiogenesis ‘Inflammation’ Lymphangiogenesis Lymphangiogenesis endothelial cell *VEGF-A = ‘VEGF’
‘Systemic’ angiogenesis (i.e., vasculogenesis) Kerbel RS. N Engl J Med 2008;358:2039-2049
Anti-VEGFR antibodies (IMC-1121b) P P P P P P P P Agents Targeting the VEGF Pathway Anti-VEGF antibodies (Bevacizumab) Soluble decoy VEGF receptors (VEGF-Trap) VEGF mTOR inhibitors (Temsirolimus, Everolimus) VEGFR-1 VEGFR-2 endothelial cell Small-moleculeVEGFR kinase inhibitors (Sunitinib, Sorafenib, Axitinib, Cediranib … )
Sunitinib Sorafenib Vatalanib VEGFR1-3 PDGFR alpha PDGFR beta RET KIT FLT-3 VEGFR1-3 C-/B-RAF PDGFR beta RET KIT FLT-3 http://www.kinomescan.com/show_data.asp
Delta-like Ligand 4 - Notch Pathway Increased angiogenesis: functionally abnormal+++ vasculature Decreased angiogenesis: vascular rarefaction reduced blood flow, severe hypoxia reduced blood flow, severe hypoxia Adapted from Hicklin DJ. Nature Biotechnology 25, 300 - 302 (2007)
‘Accidental’ Anti-Vascular Agents • chemotherapeutics • hormonal therapies • radiation therapy • COX-2 inhibitors • corticosteroids • thalidomide • LMW heparins • ACE inhibitors • propranolol • glitazones • doxycyclin • valproic acid • ... Léauté-Labrèze C, N Engl J Med. 2008;358(24):2649-51.
2004 Antiangiogenic Therapies: Phase III Success Stories 2006 Non-small cell lung cancer: Bev + PC (PFS/OS) 2007 Colorectal Cancer: Bev + FOLFOX (PFS/OS) Breast Cancer: Bev + Paclitaxel (PFS) Renal Cell Cancer:Sunitinib(PFS/OS)Sorafenib(PFS)Temsirolimus(PFS/OS) Bev + IFN-alfa 2a (PFS) 1971 Folkman Hypothesis 1983/89 VPF/VEGF 2008 Hepatocellular Ca: Sorafenib (PFS/OS) Renal Cell Cancer: Everolimus (PFS) 1997 Bevacizumab
Activity of Bevacizumab & Chemotherapy mCRC = metastatic colorectal cancer, NSCLC = non-small cell lung cancer, ABC = advanced breast cancer, IFL = irinotecan-fluorouracil-leucovorin, FOLFOX4 = oxaliplatin-fluorouracil-leucovorin, P = paclitaxel, C = carboplatin , B = bevacizumab
Underestimation of the true potential? • Antiangiogenics developed without biomarker guidance for optimal dosing: • flat dosing common for RTKIs • various bevacizumab regimens • Lack of markers for patient selection • Challenging integration into current standards of care
Rationale againstCombination Therapy • Antivascular effects I • inhibition of neo-angiogenesis • induction of endothelial cell apoptosis • impaired mobilization of CEPs and other bone marrow derived cells • vasoconstriction de Bazelaire, C. Clin Can Res 2008;14:5548-5554 reduced blood flow → decreased pO2 and nutrients availability, low pH → ANTAGONISM: reduced chemotherapy drug deposition, diminished cytotoxic activity
Rationale for Combination Therapy • Antivascular effects I • inhibition of neo-angiogenesis • induction of endothelial cell apoptosis • impaired mobilization of CEPs and other bone marrow derived cells • vasoconstriction de Bazelaire, C. Clin Can Res 2008;14:5548-5554 reduced blood flow → decreased pO2 and nutrients availability, low pH → SYNERGISM: impaired tumor cell repopulation
Rationale for Combination Therapy • Antivascular effects II • vascular ‘normalization’ Science 2005(307):58 – 62; Mol Can Ther 2008(7):3670-84
Rationale for Combination Therapy • Antivascular effects III • disruption of ‘vascular niche’ → diminished cancer stem cell compartment • impaired mobilization of CEPs and other bone marrow derived cells → impaired vascular repair → augmentation of chemotherapy-related antivascular effects
3 weeks 3 weeks Conventional (MTD) Chemotherapy Tumor cell cytotoxicity Plasma concentration of cytotoxic drug Vascular repair Vascular repair Antivascular effects Antivascular effects Antivascular effects Shaked et al. Cancer Cell. 2008;14(3):263-73. Bertolini et al. Nat Rev Cancer. 2006;6(11):835-45.
3 weeks 3 weeks Metronomic Chemotherapy Tumor cell cytotoxicity Myelosuppression Plasma concentration of cytotoxic drug Antiangiogenesis Antivascular effects Kerbel RS, Kamen BA. Nat Rev Cancer. 2004;4(6):423-36. Emmenegger U, Kerbel RS. Onkologie. 2007;30:606-608.
VEGF Targeting Agents: Beyond Antivascular Effects • Direct anti-tumor effects • Immunomodulatory effects • Mitigation of ‘cancer-associated systemic syndrome’ Xue et al PNAS 2008 105:18513-518 Anti-VEGF agents confer survival advantages to tumor-bearing mice by improving cancer-associated systemic syndrome
Clinical Applications: Challenges • phase III failures • pancreatic cancer: Bev + Gemcitabine • breast cancer: Bev + Capecitabine • colorectal cancer: Vatalanib + FOLFOX (1st and 2nd line) • diminished PFS/OS benefit in ‘2nd generation’ trials • > 50 agent(s) in clinical development • concurrent/sequential use? • continuous/intermittent use? • small molecule drugs or antibodies? • costs • side-effects • course of action in case of tumor progression? • intrinsic or acquired resistance
Resistance to Antiangiogenic (Mono-)Therapy Evasive Resistance Vascular Remodeling Co-option Reduced Vascular Dependence
NS: 1 week LDM CPA: 1 week NS: 4 weeks LDM CPA: relapse Dissociation of antiangiogenic and anti-tumor effects Emmenegger Cancer Res 66;1664-1674 (2006)
Reduced vascular dependence Hypoxia, Starvation Acute survival • Cell death ~ • Necrosis • Apoptosis • Autophagy Proliferation • Cytostasis • Autophagy dual function
‘Macro-Autophagy’ ‘Stress’ Step Structure Molecules Involved Modifiers Initiation mTOR mTOR inhibitors → autophagy stimulation Sequestration Phagophore Beclin1 (Atg6) UVRAG PI3kinase III Atg9 3-methyladenine → autophagy inhibition Autophagosome formation & maturation Autophagosome LC3 (Atg8) Atg5 Atg12 Docking & fusion with lysosome Lysosome Cathepsins Chloroquine Bafilomycin A1 → autophagy inhibition Vesicle breakdown, degradation of content, release of degradation products Autolysosome As a consequence of metabolic or treatment-related stress, autophagy is initiated and proceeds stepwise. Schematic presentation of the various steps of the autophagic cascade, the structures formed, important molecules involved and pharmacological modifiers of autophagy.
PC-3 LCR1.1 PC-3 LCR1.1 Reduced vascular dependence: a consequence of impaired autophagy? standard culture conditions 0.43% 2% metabolic stress 19.47% 5.26%
Promotion of tumor progression by antiangiogenic therapy? Accelerated metastasis after short-term treatment with a potent inhibitor of tumor angiogenesis. Ebos JM, Lee CR, Cruz-Munoz W, Bjarnason GA, Christensen JG, Kerbel RS. Cancer Cell. 2009 Mar 3;15(3):232-9. Antiangiogenic therapy elicits malignant progression of tumors to increased local invasion and distant metastasis. Pàez-Ribes M, Allen E, Hudock J, Takeda T, Okuyama H, Viñals F, Inoue M, Bergers G, Hanahan D, Casanovas O. Cancer Cell. 2009 Mar 3;15(3):220-31.
Group A Group B Group C 1 2 3 4 5 6 7 1 2 3 4 5 6 7 1 2 3 4 5 6 7 7 21 Days Post Tumor Implantation 27 30
Loges et al. Silencing or fueling metastasis with VEGF inhibitors: antiangiogenesis revisited. Cancer Cell. 2009;15(3):167-70.
Conclusions I • Antiangiogenic therapy is a clinical reality! • Angiogenesis is a highly regulated process. • Although the tumor vasculature is morpho-logically and functionally aberrant, common regulatory mechanisms remain intact and represent promising treatment targets. • Antiangiogenic agents can potentiate the anti-tumor effects of chemotherapeutics (and vice versa) but much remains to be learned to optimize the clinical benefit of such combinations.
Conclusions II • The biological understanding of the process of tumor vascularization is rapidly evolving, but this is not yet matched by the way antiangiogenic agents are used in the clinic. • There is an unmet need for biomarkers in order to optimize dosing of antiangiogenics, and for the selection of patients most likely to benefit from such agents. • Various mechanisms of intrinsic or acquired resistance to antiangiogenic agents have been described.
Conclusions III • Resistance to combinations of cytotoxic and antiangiogenic agents is less well characterized. • Stopping the administration of antiangiogenic agents at progression might facilitate tumor growth acceleration. • Novel findings suggest that antiangiogenic therapy might promote invasive tumor growth and metastatic disease progression. • Tumor promoting effects could explain the yet limited overall survival benefit resulting from the use of antiangiogenic agents and are of special concern in the (neo)adjuvant setting.
‘The greater our knowledge increases, the greater our ignorance unfolds.’ John F. Kennedy