An orally active, purine-scaffold, small-molecule inhibitor of heat shock protein 90 (HSP90) with potential antineoplastic activity. HSP90 inhibitor CNF2024 specifically blocks active HSP90, inhibiting its chaperone function and promoting the degradation of oncogenic signaling proteins involved in tumor cell proliferation and survival; this may result in the inhibition of cellular proliferation in susceptible tumor cell populations. HSP90, a chaperone protein upregulated in a variety of tumor cell types, regulates the folding and degradation of many oncogenic signaling proteins.