Compensatory Angiogenesis and Tumor Refractoriness

1. Compensatory Angiogenesis and Tumor Refractoriness Prof. Rajesh N Gacche Tumor Biology Laboratory, School of Life Sciences SRTM Univeristy, Nanded, India (MS)

2. Angiogenesis is the formation of new blood vessels from preexisting one

3. Structure of vessels and capillaries Small artery: Monocellular layer of endothelial cells Capillary: endothelial cell, basal lamina, pericytes

5. Angiogenesis is regulated by endogenous activators and Inhibitors

6. Angiogenesis is up regulated in Cancer Anti-Angiogenic factors Anti-Angiogenic factors Pro-Angiogenic factors Anti-Angiogenic factors Pro-Angiogenic factors Normal angiogenesis Excessive angiogenesis Normal angiogenesis Cancer Rheumatoid arthritis Retinopathy Psoriasis Pro-Angiogenic factors Anti-Angiogenic factors Stroke Coronary artery disease Periphery artery disease Ulcers Chronic wounds Insufficient angiogenesis

7. Tumor Process of Tumor Angiogenesis Regulate IL-1, IL-6 VEGF, FGF,PGDF, PGF, IGF, Angp, EGF, HGF, HIF, TGF, TNF, IL-3, IL-8, Ang VEGF, PGDF, IGF, Angp Cytokines, FGF VEGF Induce Expression of VEGF, FGF, PGF, IGF, Angp, EGF, HGF, HIF, TGF, IL-3, IL-8, Ang MMPs (Matrix Metallo-Proteinases) VEGF, PGF, HIF-1 4. Differentiation / Proliferation / Tube formation 5. Stabilization / Maturation 3. Migration 2. Basement membrane degradation 1. Activation

8. VEGF-Family Ang-1,2,3 Avastin , Aflibercept, Pegaptanib, FGF Pazopanib, Ranibizumab, Sunitinib HGF XL880, TAK-701, Relotumumab Regorafenib, Ponatinib PDGF Brivanib, Nintedanib, Pentosan- polysulfate Sorafenib Tie2/ Tek VEGFR-Family FGFR c-MET PDGFR PI3K PLCγ PI3K SHC PI3K RAS PI3K RAS PLCγ DAG PIP3 RhoA Vav1 IP3 FAK RAC1 CDC42 Vav2 cRAF IP3 PKC AKT Pathway PIP2 AKT Pathway Actin, Stress fibres & Adhesion CDC42 NOSIII MEK 1/2 Paxillin Rac1 CamK II CDC42 Pathway RAC1 Pathway PIP3 NO N-WASP ERK 1/2 Por1 Por2 Cell Proliferation Caspase 9 Regulation of Cytoskeleton PIP2 BAD Vasodilation/ Permeability Lamellipodia/ Filopoda Formation Cell Survival Cell Migration A n g i o g e n e s i s

9. Targeting Tumor Angiogenesis for designing novel drugs • 3D structural information of angiogenic proteins has profoundly influenced the philosophy of drug design and development. • There have been major and striking advances in protein crystallography. • Structures solved by protein crystallography are exceptionally valuable and forms foundation for effective ligand design. • Structural knowledge can be effectively utilized in developing better therapeutic agents for modulation of angiogenesis in cancer therapy.

10. VEGFR-1 These interactions have opened novel therapeutic avenues to study the role of VEGFR-1-specific ligand in angiogenesis-mediated pathologies. Hydrophobic contacts Hydrogen bonds VEGF-B These contacts can be utilized in generating peptide mimetic inhibitor molecules that can modulate VEGF-C interaction with VEGFR-2 VEGFR-2 VEGF-C

11. FGF-2 These interactions provide a structural insight to design therapeutic agents that can target FGF-2::FGFR interactions. FGFR FGF-1 Interactions at interface of FGF-1::FGFR opens new avenues for rational drug design targeting FGF1-induced angiogenesis and cell proliferation. FGFR

12. PGDFR Such biochemical communications can be efficiently utilized to modulate PGDF β-receptor interaction in therapeutic context. PGDF- β VEGFR-1 These interactions hold a key to design strategy for modulation of PGF-VEGFR-1 interaction. PGF

13. IGFBP Interactions at IGFBP and IGF can guide development of interaction based inhibitors. IGF Tie2K These contacts at ATP binding site can be utilized to develop therapeutically relevant agents targeting Tie2K activity.

14. Biochemical interactions at EGF::EGFR interface possess enormous potential to develop contact based therapeutic agents. EGF EGFR HGF These interactions at HGF::c-Met thus provide an opportunity to selectively modulate HGF activity as antagonist for cancer therapy. C-Met

15. Interactions at HIF-CBP complex can be extensively used to develop small molecule transcriptional modulators. CBP HIF All these interactions at TGF::EGFR possess lot of potential to be therapeutically targeted.

16. More about structural opportunities for developing anti-angiogenic agents

17. Source: Rakesh Jain, Cancer Cell 26, November 10, 2014

18. Clinical Research in Angiogenesis Inhibitorsas on 1st Nov 2015 • 3512 Clinical trials are registered • 1445 Trials have been completed (41 %) • 356 Trials have been Terminated (10 %) • 89 Trials have been withdrawn (2.5 %) • 14 Trials have been suspended (0.4 %) Source: Clinical Trials.gov

19. Arguments ? • Targeting Tumor Angiogenesis: a Right target or a Wrong Choice ? • Why the tumors growth is more aggressive after drug holidays ? • Why there is evolving drugs resistance towards anti-angiogenic agents ? • Does the compensatory angiogenic mechanismsis the major factors in limiting the efficacy of anti-angiogenic therapy ?

20. Targeting Angiogenesis: Right target or a Wrong Choice ? Targeting tumor angiogenesis: an attractive target with emerging challenges • Pathophysiological point of view • Without neovascularisation • No tumor growth beyond a size of 2 mm • No metastasis pharmacological point of view How will you supply an anti-cancer drugs to the tumor without an appropriate blood supply?

21. ‘Normalization of tumor vasculature’: a new paradigm by Prof. Rakesh Jain • Blood vessels of tumor are more complex, dilated, tortuous, hyperpermeable and disorganized • This makes the access of drug molecules difficult to reach every cell of tumor body. • Instead of killing the entire tumor vessels, it is imperative to normalize (organized vessel complex) it initially? • Appropriate doses of anti-antiangiogenic drugs has been shown to normalize the vessels.

22. Appropriate doses of anti-antiangiogenic drugs has been shown to normalize the vessels. Goel S et al. Physiol Rev 2011;91:1071-1121

23. Inbuilt threats of targeting tumor angiogenesis • At present anti-angiogenic agents can not discriminate between physiological and pathological angiogenesis. • Hence, hampers normal angiogenesis. • Anti-angiogenic agents lack efficacy due to prevalence of compensatory angiogenesis pathways. • Off-target toxicities unrelated to blockade of physiological angiogenesis………another big issue!!

25. Conspiracy of Compensatory Angiogenesis in acquired drug resistance • A. VEGF dependent • B. VEGF independent: • FGF, PDGF, Angiopetins, Ephrins etc • DLL4-Notch Signalling C. Myeoloid & Stromal/Tumor Cell mediated angiogenic reprogramming. D. Angiogenesis independent remodeling mechanisms like vascular mimicry, vessel cooption and in intussusceptive angiogenesis

26. Source: Gacche RN, 2015,Oncogenesis (Nature)

27. VEGF-axis dependent and non-VEGF mediated mechanisms of resistance to anti-angiogenic therapies Source: Gacche RN, 2015,Oncogenesis (Nature)

28. VEGF bypass pathways Avastin PlGF Proteolytic cleavage Endothelial cell VEGF-D VEGF -C VEGF-A VEGF-A By pass FGF DLL-4 Synergistic activity VEGFR-2 VEGFR-3 FGFR NOTCH VEGFR-3 Sustained Angiogenesis in VEGFR-2 Inhibition State VEGF – A Signaling FGFR Signaling Synergistic Inhibition NOTCH Signaling Up regulate Cell Proliferation Cell Migration Vasodilatation/ Permeability Cell Survival anti-angiogenic resistance in VEGFA targeted therapies A n g i o g e n e s i s

29. Source: Gacche RN, 2015,Oncogenesis (Nature)

30. Source: Gacche RN, 2015,Oncogenesis (Nature)

31. Source: Gacche RN, 2015,Oncogenesis (Nature)

32. Conclusions • Based on the present clinical and epidemiological literature it is clear that the future settings of targeting tumor angiogenesis should customize more on inhibiting the compensatory angiogenic pathways/factors so as to improve the efficacy of anti-angiogenic agents. • Developing anti-tumor agents hitting multiple targets are more appreciated in the midst of evolving resistance of cancer cells towards present day anticancer drugs

34. In silicowork of di-, tri-, tetra-, and penta-hydroxy substituted flavones Nanded Thank you • Quantum chemical descriptors