Kassoum Nacro¹, Haiyan Yang¹, Melvyn Ho¹, Joseph Cherian¹, Samantha Guo¹, Po Zhi Ying¹,Thomas Keller¹, CongBao Kang¹, Young Mee Kim¹, Shovanlal Gayen¹, Qiwe Huang¹, Angela Chen¹, Joma Kanikadu Joy¹, Thuy Thi Hanh Nguyen¹, Boping Liu¹, Esther Ong¹, Jeffrey Hill¹, Jacklyn Yong¹, Choong Meng Ling¹, Lee May Ann¹, Kanda Sangthongpitag¹, Vishal Pendharkar¹, Tai Shi Jing¹, Saha Sudipta¹, Tiong Sin Ong², Sharon Lim², Ralf Jauch³, Christopher Brown⁴

1. Experimental Therapeutics Centre, A*STAR, 31 Biopolis Way, #3-01, Singapore 138669
2. Cancer and stem cell biology Program, Duke-NUS Graduate Medical School, 8 College road, Singapore 169857
3. Genome Institute of Singapore, A*STAR, 60 Biopolis Street #02-01Genome, Singapore 138672
4. p53 Laboratory, A*STAR, 8A Biomedical Grove, #06-06, Immunos, Singapore 138648

Introduction

The eukaryotic translation initiation factor 4E (eIF4E) is frequently overexpressed in several types of human cancers and is associated with cellular transformation, tumorigenesis, and metastatic progression. eIF4E has also been linked to poor prognosis in patients with solid tumors. Mitogenactivated protein kinase-interacting kinases 1 and 2 (Mnk1 and Mnk2) are downstream effectors of mitogen-activated protein kinase pathways and phosphorylate eIF4E on serine 209. This phosphorylation has been reported to be required for eIF4E oncogenic activity.

Rationale

Knock-in mice, in which the eIF4E serine 209 was mutated to alanine, are resistant to oncogeneinduced transformation and to Pten loss-induced prostate cancer (1). Phosphorylation of eIF4E is completely abolished in Mnk1 and Mnk2 double knock-out mice which are either resistant to transformation or significantly retard tumor formation (2). Mnk DKO mice and eIF4ES209A mice are viable with no apparent abnormalities or defects.

These data suggest that inhibitors of Mnk1 and Mnk2 may be effective anticancer drugs and are likely to have minimal side effects.

Aim

Our aim is to develop Mnk 1&2 inhibitors with the following attributes:

• in vitro IC50 < 50 nM
• Bioavailability > 30%
• Cyp 3A4, 2D6 IC50 >10 μM
• hERG IC50> 10 μM

Lead Finding Strategy

• Literature
• Fragments screening
• HTS
• Virtual
• Cross validate binding by at least two biophysical techniques

Structural Biology

Crystallography

NMR Studies

Fragment-based Drug Discovery

Fragments from literature (3) with good ligand efficiency (LE) could be the starting point to design and synthesize potent Mnk inhibitors.

LE measures the binding energy per atom.

Biophysics: Thermofluor
Potent ligand such as ETC-1693110 and ETC-1693112 increase Mnk2 thermal unfolding by 23°C!

Biological Results

Binding and cell-based assays

Pharmacokinetics of Lead Molecule ETC-1780445

References

1. Luc Furic et al PNAS 2010, 107 (32), 14134-14139.
2. Takeshi Ueda et al PNAS 2010, 107 (32), 13894-13990
3. Julen Oyarzabal et al J. Med. Chem., 2010, 53 (18), pp 6618–6628

Acknowledgements

We would like to thank A*STAR Biomedical Research Council for financial support.

Conclusion

• ETC-1780445-2 is a potent Mnk 1/2 inhibitor, that demonstrates high selectivity against other kinases
• ETC-1780445-2 shows excellent drug like properties
• Access to proprietary compounds with divers kinase selectivity profile to should allow us to fully assess the benefits of Mnk1/2 inhibitors.