Farmacologia degli inibitori TK e mtor Romano Danesi Professore ordinario di Farmacologia UOC Farmacologia Universitaria Azienda Ospedaliero-Universitaria Pisana Dipartimento di Medicina Interna Università di Pisa Farmacologia inibitori TKI e mtor 1
The TKI dilemma: antiangiogenic vs. global inhibitors Farmacologia inibitori TKI e mtor 2
Common pharmacologic questions on TKI Do TKI differ by affinity, potency, specificity? What are the determinants of potency? Is selectivity a therapeutic advantage? Farmacologia inibitori TKI e mtor 3
Key definitions: drug-target interactions k 1 D + R DR Complex Effect k 2 Drug-receptor binding is transient and reversible k 1 - Rate at which drug associates with receptor k 2 - Rate at which drug dissociates from receptor Farmacologia inibitori TKI e mtor 4
Key definitions: drug-target affinity k 1 D + R DR Complex Effect k 2 Affinity is a quantitative measure of the attraction between drug molecules and receptors Kd or dissociation constant is a measure of drug affinity for a specific receptor Affinity can be determined as: Kd = k 2 /k 1 Farmacologia inibitori TKI e mtor 5
To summarize Drug High affinity Target Drug Low affinity Target Selective interaction Drug Non-selective interaction Drug Target Target Farmacologia inibitori TKI e mtor 6
Key definitions: drug potency is the dose necessary to produce a given effect Factors affecting drug potency: Accessibility (Pharmacokinetics) Affinity (Pharmacodynamics) Intrinsic activity (Pharmacodynamics) Farmacologia inibitori TKI e mtor 7
IC50 values of pazopanib, sunitinib, and sorafenib against kinases Kumar R et al. British Journal of Cancer (2009) 101, 1717 1723 Farmacologia inibitori TKI e mtor 8
Half maximal inhibitory concentration (IC50: nmol/l) of TKI for receptor tyrosine kinases VEGFR1 VEGFR2 VEGFR3 c-kit PDGFRα PDGFRβ Axitinib 1.2 0.2 0.1-0.3 1.7 5 1.6 Sunitinib 2 50 17 15 69 4 Sorafenib - 90 20 68 -- 80 Pazopanib 10 47 30 74 71 84 Goldstein R et al. Expert Rev Anticancer Ther 2010; 10(10): 1545-1557 Farmacologia inibitori TKI e mtor 9
Relative potencies and selectivities of VEGFR TKIs Farmacologia inibitori TKI e mtor 10
What is the role of Flt-3 in RCC immunity? Flt-3 suppression may restore, at least in part, immune response by suppressing T- reg and myeloid-suppressor cells Farmacologia inibitori TKI e mtor 11
What is the role of PDGF in resistance to VEGF inhibitors? 1 Oromi A et al Cell 2005 3 Du R Cancer Cell 2008 2 Ebos JM et al PNAS 2007 SDF1α CAFs Osteopontin PDGF BMDCs MMP9 SDF1α Adapted from Casanovas O Cancer Cell 2005 Bone marrow derived cells (i.e myeloid suppressive cells) Cancer associated fibroblasts R. Danesi Farmacologia inibitori TKI e mtor 12
Does selectivity turn into a therapeutic advantage or not? Farmacologia inibitori TKI e mtor 13
Farmacologia inibitori TKI e mtor 14
Effect of TKI on cellular kinases Farmacologia inibitori TKI e mtor 15
Effect of TKI on cellular kinases Pazopanib Farmacologia inibitori TKI e mtor 16
Are all multi-targeted tyrosine kinase inhibitors created equal? An in vitro study of sunitinib and pazopanib in renal cell carcinoma cell lines Daniel Canter, MD, Alexander Kutikov, MD, Konstantin Golovine, MD, Petr Makhov, MD, Jay Simhan, MD, Robert G. Uzzo, MD, Vladimir M. Kolenko, MD Division of Urologic Oncology, Department of Surgery, Fox Chase Cancer Center, Philadelphia, Pennsylvania, USA The Canadian Journal of Ur ology ; 18(4); August 2011 Farmacologia inibitori TKI e mtor 17
Effect of sunitinib and pazopanib on proliferation of human renal carcinoma cells Farmacologia inibitori TKI e mtor 18
Effect of sunitinib and pazopanib on apoptosis of human renal carcinoma cells Farmacologia inibitori TKI e mtor 19
The role of rapalogs in the treatment of cancer Farmacologia inibitori TKI e mtor 20
Inhibition of the PI3K/AKT/mTOR pathway Schatz JH. Curr Oncol Rep (2011) 13:398 406 Farmacologia inibitori TKI e mtor 21
Chemical structures of rapamycin analogs in oncology clinical trials Boni JP. Semin Oncology, 36 (6, Suppl 3):2009, S18-S25 Farmacologia inibitori TKI e mtor 22
Mean plasma concentrations of CCI-779 (solid) and sirolimus following intravenous doses Raymond E, et al. J Clin Oncol 22:2336-2347, 2004 CCI-779 displayed no immunosuppressive effects with manageable and reversible adverse events at doses up to 220 mg/m 2, the highest dose tested. Farmacologia inibitori TKI e mtor 23
Measurement of mtor/p-s6rp inhibition in healthy subjects following treatment with IV temsirolimus Fraction of Base eline Response 1.0 0.9 0.8 0.7 0.6 0.5 0.4 0.3 0.2 CD3+ PBMCs Time (hours) Temsirolimus Dose 1 mg 3 mg 10 mg 15 mg 25 mg 0 24 48 72 96 120 144 168 Boni JP. Semin Oncology, 36 (6, Suppl 3):2009, S18-S25 Farmacologia inibitori TKI e mtor 24
Relationship between proportional decrement in p70s6 kinase activity and time to tumor progression Peralba JM et al. Clin Cancer Res 2003;9:2887-2892 Farmacologia inibitori TKI e mtor 25
Effect of temsirolimus on Akt (Ser473) and ps6 phosphorylation in the Jeko1 MCL cell line Younes A, Autophagy 4 (5): 707-709, 2008 Farmacologia inibitori TKI e mtor 26
Mechanisms of rapalog resistance Nawrocki ST et al. Targ Oncol (2011) 6:17 27 Farmacologia inibitori TKI e mtor 27
Conclusions An enhanced potency of TKI inhibitors may overcome the limitations of drug distribution associated with tumor vascularization. The ability to inhibit PDGF may be important because the development of resistance to angiogenesis inhibitors may be due to upregulation of VEGF alternative pathways. Overall biologic efficacy may be enhanced by broadening the targets of kinase inhibition. Inhibition of mtor signaling is better defined within PK/PD models. The FKBP12-independent effect could be directly related to the antitumor activities of rapalogues in cancer patients independent of immune suppression. Farmacologia inibitori TKI e mtor 28