For non-us, non-canada, non-uk healthcare professionals only Plk inhibition Mechanism of Action Slide kit

Transcription

1 Procedure ID: October 2014 For non-us, non-canada, non-uk healthcare professionals only Plk inhibition Mechanism of Action Slide kit

2 Polo-like kinases (Plks) are an emerging focus for the haemato-oncology community

3 Plks are protein kinases, a drug target of interest in oncology Protein kinases catalyse protein phosphorylation and regulate a number of essential functions in the cell: cellular proliferation, differentiation, and organisation of cellular structures. 1 There are four main classes of protein kinases: 2 The well known tyrosine kinases (TKs), which phosphorylate tyrosine. Non-receptor TKs. Lipid kinases. Serine-threonine kinases, which phosphorylate serine or threonine. Deregulation of protein kinase activity is one major mechanism by which cancer cells evade normal physiological constraints on growth and survival. 3 Polo-like kinases (Plks) are members of the serine/threonine kinase family 5 Plks have been identified so far. 4,5 1. Lee KS et al. Mol Cell Biol 1995;15(12): Zhao H-Yet al. J Cancer Res Updates 2013;2: Zhang J et al. Nat Rev Cancer 2009;9(1): Strebhardt K. Nat Rev Drug Discov 2010;9(8): Louwen F, Yuan K, Oncotarget 2013;4(7):958-71

4 Plks share similar structural features and can be blocked by specifically designed ATP-competitive inhibitors All members of the PLK family contain an amino-terminal kinase domain and a carboxy-terminal polo box domain (PBD), which is unique to the PLK family. 1 When the Polo-box binding (PB) domain is bound to the kinase domain, it inhibits kinase activity 2 After phosphopeptide binding to PB domain, the kinase domain is released and free to bind to its target substrates 2 ATP-competitive inhibitors have been designed to bind to the ATPbinding pocket 2,3 Schematic representation of the structure and physiological function of the Polo-like kinase (PLK) family. (adapted from Schöffski P, 2009). 1. Strebhardt K. Nat Rev Drug Discov 2010;9(8): Schöffski P. The Oncologist 2009;14: Zhang J et al. Nat Rev Cancer 2009;9(1):28-39

5 Plk1 is the best characterised member of the Plk family 1 Plk1 has an ATP-binding site in the amino-terminal kinase domain. 1 The ATP binding site participates in the phosphorylation of proteins involved in the machinery of mitosis Tsykunova G et al. Expert Opin Investig Drugs 2012;21(5): Lowery DM et al. Oncogene 2005;24(2):248-59

6 Plk1 is crucially involved in many aspects of the cell cycle progression, including early mitotic events 1-3 PLK1 controls critical steps in the passage of cells through mitosis, including: initiation of entry into mitosis, centrosome maturation and separation, formation of the bipolar spindle, metaphase to anaphase transition and initiation of cytokinesis. 4 Plk1 is cell-cycle dependent: it is only expressed in dividing cells, mainly during late G2 and mitosis. 1,5-7 Functions and localisation of Plk1 during mitosis. 8 Plk1 (green) localises at centrosomes and kinetochores in prometaphase, metaphase, and at the midzone/midbody in later stages of mitosis. 1. Strebhardt K. Nat Rev Drug Discov 2010;9(8): Louwen F, Yuan J. Oncotarget 2013;4(7): Salaun P et al. Adv Exp Med Biol 2008;617: Schöffski P. The Oncologist 2009;14: Chopra P et al. Expert Opin Investig Drugs 2010;19(1): Lee KS et al. Mol Cell Biol 1995;15(12): Cholewa BD et al. Cancer Res 2013;73(23): Lens SMA et al. Nature Rev Cancer 2010;10:825-41

7 Plk1 inhibition causes an early and significant change in the course of mitosis In cells undergoing division, Plk1 inhibition induces an early and significant change in the course of mitosis, right after prophase: 1 Plk1 inhibition causes perturbation of spindle assembly and induces monopolar spindles This change leads to a distinct and persistent Polo arrest phenotype 1,2 and ultimately to apoptosis. Plk1 inhibition showing the characteristic Polo arrest phenotype Schöffski P. The Oncologist 2009;14: Lens SMA et al. Nature Rev Cancer 2010;10:825-41

8 After treatment with a Plk1 inhibitor, cancer cells accumulate in Polo arrest With Plk Inibition Cancer cells in Polo arrest (after treatment with a Plk1 inhibitor). Without Plk Inibition Cancer cells treated with control are able to complete mitosis and divide. Cancer cells (HeLa) treated with a Plk1 inhibitor. After treatment with a Plk1 inhibitor or carrier (DMSO), cancer cells were fixed with formaldehyde and stained with DAPI (DNA stain; blue), alpha-tubulin antibody (microtubules and mitotic spindle protein; green) and Crest antiserum (binds to centromeric proteins that attach to the mitotic spindle; red). Images courtesy of Dr. Péter Lénárt.

9 Polo arrest leads to apoptosis Polo arrest phenotype induces a monopolar spindle. 1,2 Monopolar spindle in Polo arrest phenotype. Bipolar spindle in mitosis. Monopolar spindle is a major perturbation of mitosis that leads to apoptosis. 1,2 Perturbation of the spindle assembly causes activation of the mitotic checkpoint, prolonged mitotic arrest, and finally apoptosis. 1 Apoptosis. 1. Schöffski P. The Oncologist 2009;14: Lens SMA et al. Nature Rev Cancer 2010;10:825-41

10 Plk1 inhibition appears as a development approach of interest in haemato-oncology

11 High levels of Plk1 are seen in many cancers, including AML Plk1 is highly expressed in many cancers (e.g. breast cancer, colorectal cancer, non-small cell lung cancer, pancreatic cancer, skin cancer), as well as in haematologic malignancies (e.g. acute myeloid leukemia AML). 1-4 In contrast, in most other adult tissues containing non-dividing cells, it is either undetectable or present at very low levels. 5 Elevated expression of Plk1 has been associated with invasive growth and poor prognosis in some cancers. 6 Leukemic cells in bone marrow. In AML, the levels of Plk1 are high in leukemic cell lines and in a majority of samples from patients Strebhardt K. Nat Rev Drug Discov 2010;9(8): Berg T et al. Expert Opin Investig Drugs 2012;21(8): Weiß L, Efferth T. Exp Hematol Oncol 2012;1(1):38 4. Renner AG et al. Blood 2009;114: Winkles JA, Alberts GF. Oncogene 2005;24(2): Takai N et al. Oncogene 2005;24:287-91

12 There are several reasons why Plk1 could potentially be an attractive molecular target in AML The hallmark of AML is a high mitotic rate 1 The disease is associated with a short-tumour doubling time (2.5 days). Plk1is expressed during mitosis, which is a critical point for intervention in cancer therapy. 1,2 Indeed, cancer cells, which often have a high proliferation rate, are fragile when they undergo division. Dividing leukemic cells. In consequence, AML may be particularly sensitive to Plk inhibition, since leukemic cells are most likely dependent on Plk1 for their proliferation Chan KS et al. Cell Death Dis 2012;3:e Spänkuch-Schmitt B et al. J Natl Cancer Inst 2002;94: Renner AG et al. Blood 2009;114:659-62

13 In vitro and in vivo findings support the interest of Plk1 inhibition as a new approach to cancer therapy The reduction of cancer cell proliferation by Plk1 inhibition has been observed in various tumour models in vitro and in vivo: 1 In cell lines derived from carcinomas of the colon (HCT 116) and lung (NCI-H460), melanoma (BRO), and haematopoietic cancers (GRANTA-519; HL-60; THP-1and Raji). 2 In leukemic cell lines as well as in primary human AML cells. 3 In xenograft models of NSCLC and colon carcinoma, and in a model of taxaneresistant colon carcinoma. 2 In a xenograft model of AML, where marked antitumour activity and good tolerability were observed Murugan RN et al. Mol Cells 2011;32: Rudolph D et al. Clin Cancer Res 2009;15(9): Renner AG et al. Blood 2009;114: Gjertsen BT and P Schöffski P. Leukemia advance online publication, 15 August 2014;doi: /leu AML xenograft model. Median tumor volumes after 4 weeks of treatment by a Plk inhibitor (volasertib*) of nude mice bearing established subcutaneous MV4-11 AML tumors - Eight animals per treatment group - vehicle (light blue squares) or *volasertib at 40 mg/kg (blue circles), 20 mg/kg (green triangles), or 10 mg/kg once a week (black squares), or at 20 mg/kg two times a week on consecutive days (red triangles). *Volasertib is an investigational compound and is not yet approved. Its efficacy and safety have not yet been fully established. Plk Inibition

14 Plk inhibitors in clinical development A number of Plk inhibitors are currently in early stage of clinical development, in various tumour types. 1,2 Their antitumour activity needs to be confirmed in additional large studies. 3 *Volasertib is currently being developed in AML, in a clinical trial programme including studies in previously untreated patients and patients with relapsed/refractory disease. 4 Encouraging data from the phase II part of the AML trial has prompted the initiation of a phase III trial of volasertib in AML (POLO-AML-2). 4 Plk ATP *Volasertib (blue) selectively and potently inhibits Plk by competitively inhibiting ATP binding 3 *Volasertib is an investigational compound and is not yet approved. Its efficacy and safety have not yet been fully established. 1. Strebhardt K. Nat Rev Drug Discov 2010;9(8): Chan KS et al. Cell Death Dis 2012;3:e Schöffski P. Oncologist 2009;14: Gjertsen BT and P Schöffski P. Leukemia advance online publication, 15 August 2014;doi: /leu

15 *Volasertib in Phase III clinical development 1 The POLO-AML-2 trial is a randomised double-blind phase III trial evaluating *volasertib plus LD-Ara-C compared with placebo plus LD-Ara-C in patients 65 years of age with previously untreated AML, who are considered ineligible for intensive induction chemotherapy. 2 N=660 2:1 Randomization Volasertib + LDAC Placebo + LDAC Primary endpoint: CR + CRi rate Secondary endpoints: Overall Survival (OS), Event Free Survival (EFS), Relapse-Free Survival (RFS) *Volasertib is an investigational compound and is not yet approved. Its efficacy and safety have not yet been fully established. 1. Boehringer Ingelheim press release, accessed on september 9, 2014, 2. Accessed on september 9, 2014:

16 Interference with the regulation of mitosis *Volasertib is a selective and potent cell cycle kinase inhibitor. It acts on the mitotic spindle by interfering with the regulation of the mitotic process. 1 Treatments that act on the mitotic process directly bind to structural components of the spindle itself, but do not interfere with the regulation of mitosis. 1 Volasertib interferes with the regulation of mitosis and induces the Polo arrest phenotype. Unlike treatments that act on the mitotic process, *volasertib does not disrupt microtubule dynamics in non-cycling cells. 2 *Volasertib is an investigational compound and is not yet approved. Its efficacy and safety have not yet been fully established. 1. Schöffski P. The Oncologist 2009;14: Lapenna S, Giordano A. Nature Rev. Drug Discovery 2009;8:547-66

17 Plk inhibition in cancer Most available options in AML are active at the S phase: 1-4 Azacitidine is active mainly in G1-phase and, to a lesser degree, in S-phase Little progress has been made in AML treatments for 10 years or more, especially for older patients who are not eligible for induction chemotherapy. 1,3 Current agents interfere with DNA synthesis e.g.: DNA methyltransferase inhibitors: decitabine 2 azacitadine. 2 DNA synthesis inhibitors: cytarabine. 1 DNA methyltransferase inhibitor: azacitadine. 4 Cell-cycle targets of current agents used to treat elderly AML patients ineligible for induction chemotherapy. 1. Fathi AT et al. Cancer Treat Rev 2010;36(2): Howell Jr PM et al. Pharmaceuticals 2010; 3: Kantarjian H et al. J Clin Oncol. 2012;30: Robak T. Expert Opin Investig Drugs 2011;20(3):343-59

18 Copyright 2014 Boehringer Ingelheim International GmbH. All rights are reserved. This Slide kit is subject to local MLR approval for implementation on a country level.