Development of Hsp90 beta-selective inhibitors as safer anti-cancer agents

Abstract
The 90 kD heat shock proteins (Hsp90) are molecular chaperones that are responsible for the folding of select
proteins, many of which are directly associated with cancer progression. Consequently, inhibition of the Hsp90
protein folding machinery results in a combinatorial attack on numerous oncogenic pathways. Seventeen small
molecule inhibitors of Hsp90 have entered clinical trials for the treatment of cancer, all of which bind the Hsp90
N-terminus and exhibit pan-inhibitory activity against all four Hsp90 isoforms. Pan-Inhibition of Hsp90 appears
to be detrimental as toxicities have been reported alongside induction of the pro-survival heat shock response.
The development of Hsp90 isoform-selective inhibitors represents an alternative approach towards the
treatment of cancer and may reduce side effects observed with pan-Hsp90 inhibition. This application
proposes optimization of a novel class of Hsp90β-selective inhibitors that induces the degradation of select
Hsp90 clients without simultaneous induction of Hsp90 levels. Preliminary work involving Hsp90β-selective
compounds at University of Notre Dame has established that Hsp90β inhibition offers a targeted and safer
therapeutic approach for the treatment of cancer. In this Phase I, PrevAllergy (d/b/a Grannus Therapeutics) will
optimize the efficacy and drug like properties of the novel Hsp90β-selective inhibitor using a rational, structure-
based drug design approach to obtain a lead compound. Aim 1. Optimize the current lead Hsp90β-selective
compounds by synthesizing rationally designed new analogs to improve affinity, pharmacokinetic properties
and metabolic stability of the discovered series of Hsp90β-selective inhibitors. The working hypothesis is that
introduction of functional groups will increase drug-likeness of our current lead compounds. Aim 2. Evaluate
Hsp90β-selective inhibitors developed in Aim 1 utilizing pharmacokinetic assays and in vitro cellular studies,
and in vivo studies to assist in the identification of a drug candidate. Based on the teamandapos;s preliminary cellular
studies involving multiple cancer cell lines, cancers with increased dependency upon Hsp90β have been
identified, animal models of these identified cancer will be treated. Upon completion of the proposed work,
Grannus Therapeutics will have identified lead compounds with improved drug-like properties to progress into
Investigational New Drug (IND)-enabling studies. The result from Phase II will lead to an IND application and
subsequent initiation of clinical trials to treat the identified cancers that still represent an unmet medical need.
!Project Narrative
The proposal addresses the need for development of safer anti-cancer therapeutics. We will prepare
compounds that inhibit beta isoform of protein Hsp90, which is a known driver of cancer. These compounds
will differ from the current Hsp90 inhibiting drugs by providing a safer dosing profile in comparison with current
therapeutic options. The proposed work is essential for identifying a lead compound for pre-clinical studies.
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