7
ème
JOURNÉE ROGER MONIER
« Anti-tumor drug design and mode of action
»
LUNDI 14 MARS 2015 à 13h30
Amphithéâtre de l’Espace Maurice Tubiana
A Gustave Roussy - Villejuif
Co-organisée par Gustave Roussy et l’Institut Curie
Paul WORKMAN Institute of Cancer Research – Londres, UK
“Designing chemical probes and drugs for the cancer genome”
Precision genomic medicine is now a reality in the clinic. There are numerous successful
examples of ‘drugging the cancer genome’. However, only 5% of the cancer genome is
drugged. Furthermore, a major emerging challenge for drug design and use is the
inexorable development of resistance as a result of adaptive biochemical and
transcriptional feedback loops and the selection for genetically more aggressive and
resistant clones – the survival of the nastiest. There is an urgent need for innovative drug
discovery to explore the 95% of the cancer genome that remains undrugged, and to
discover new drugs and combinations that overcome drug resistance.
Since 2005, our Cancer Research UK Cancer Therapeutics Unit at The Institute of Cancer,
London has discovered 20 new drug candidates and progressed 8 of these into clinical
trials, almost all with our hospital partner the Royal Marsden Hospital. And out drug
abiraterone, designed and synthesised at ICR and initially trialled with RMH, was
approved in 2011 and has now been used to treat hundreds of thousands of men with
advanced prostate cancer.
I will describe case histories from our work that exemplify the role of academic drug
discovery efforts – often operating productively in partnership with biotech and pharma
companies. I will in particular illustrate the challenges of target selection and validation in
the post-genomic era; describe the power of structure-based drug design; demonstrate
the importance of target engagement biomarkers; and explore the promise and perils of
chemical probes for the cancer genome.
William Georges KAELIN Dana-Farber Cancer Institute – Boston, MA
”New cancer treatment strategies emerging from studies of the VHL and IDH proteins”
Loss of the VHL tumor suppressor protein (pVHL) is the truncal event in most kidney
cancers. pVHL is part an ubiquitin ligase that targets the alpha subunits of the HIF
transcription factor for degradation. Binding of pVHL to HIFα requires that HIFα be prolyl
hydroxylated by the EglN 2-oxoglutarate (2-OG)-dependent dioxygenases, which are
oxygen sensors. A drug that specifically inhibits HIF2α is efficacious in preclinical pVHL-
defective kidney cancer models and has entered the clinic. Our recent work with
lenalidomide suggests another strategy for targeting transcription factors such as HIF2α:
small molecule mediated target destabilization. We are also identifying enzymes that
become more essential once pVHL is lost (synthetic lethality).
Some cancers, including some acute leukemias and gliomas, are caused by IDH1 or IDH2
mutations. These mutations cause the accumulation of mM amounts of R-2
hydroxyglutarate (R-2HG). R-2HG can interfere with (usually inhibit) the activities of
various 2-OG-dependent enzymes, including the JmjC histone demethylases, the TET DNA
hydroxylases, and the EglN prolyl hydroxylases. We showed that the effects of R-2HG in
leukemia are reversible. Consistent with this, drugs that inhibit R-2HG production are
active in leukemia patients. It is less clear whether the effects of R-2HG will be reversible
in glioma. Nonetheless, we have identified vulnerabilities created by high R-2HG levels
that can be exploited in this setting.