Identification and Characterization of New Chemical Entities Targeting Apurinic/Apyrimidinic Endonuclease 1 for the Prevention of Chemotherapy-Induced Peripheral Neuropathy

Abstract

Chemotherapy-induced peripheral neuropathy (CIPN) is a potentially debilitating side effect of a number of chemotherapeutic agents. There are currently no U.S. Food and Drug Administration-approved interventions or prevention strategies for CIPN. Although the cellular mechanisms mediating CIPN remain to be determined, several lines of evidence support the notion that DNA damage caused by anticancer therapies could contribute to the neuropathy. DNA damage in sensory neurons after chemotherapy correlates with symptoms of CIPN. Augmenting apurinic/apyrimidinic endonuclease (APE)-1 function in the base excision repair pathway reverses this damage and the neurotoxicity caused by anticancer therapies. This neuronal protection is accomplished by either overexpressing APE1 or by using a first-generation targeted APE1 small molecule, E3330 [(2E)-2-[(4,5-dimethoxy-2-methyl-3,6-dioxo-1,4-cyclohexadien-1-yl)methylene]-undecanoic acid; also called APX3330]. Although E3330 has been approved for phase 1 clinical trials (Investigational New Drug application number IND125360), we synthesized novel, second-generation APE1-targeted molecules and determined whether they would be protective against neurotoxicity induced by cisplatin or oxaliplatin while not diminishing the platins' antitumor effect. We measured various endpoints of neurotoxicity using our ex vivo model of sensory neurons in culture, and we determined that APX2009is an effective small molecule that is neuroprotective against cisplatin and oxaliplatin-induced toxicity. APX2009 also demonstrated a strong tumor cell killing effect in tumor cells and the enhanced tumor cell killing was further substantiated in a more robust three-dimensional pancreatic tumor model. Together, these data suggest that the secondgeneration compound APX2009 is effective in preventing or reversing platinum-induced CIPN while not affecting the anticancer activity of platins.

Ref-1/APE1 as a Transcriptional Regulator and Novel Therapeutic Target in Pediatric T-cell Leukemia

“…We also evaluated the effect of second generation Ref-1 inhibitors APX2007, APX2009 and APX2032 on leukemia cell viability on TAIL7 cell (Figure 4H–J). The IC50s ranged from 2.5 to 5.0 μM for the three compounds and is consistent with our evaluations of these agents, particularly APX2009, demonstrating 5–10 increased efficacy (33). …”

“…E3330 was synthesized by the University of Michigan Vahlteich Medicinal Chemistry Core Facility (Dr. Hollis Showalter), as previously described (7, 32). Analogs of E3330 (APX2007, APX2009 and APX2032) were synthesized by Cascade Custom Chemistry (Eugene, OR) as described (33). The synthesis steps include a common intermediate, iodolawsone (2-iodo-3-hydroxy-1,4 naphthoquinone which is reacted with methacrylic acid or 2-propylacrylic acid, along with oxalyl chloride and the corresponding amine, and with sodium methoxide in methanol to yield APX2007 [(2 E )-2-[(3-methoxy-1,4-dioxo-1,4-dihydronaphthalen-2-yl)methylidene]- N , N -dimethylpentanamide], APX2009 [(2 E )-2-[(3-methoxy-1,4-dioxo-1,4-dihydronaphthalen-2-yl)methylidene]- N , N -diethylpentanamide], and APX2032 [(2 E )-2-(3-methoxy-1,4-dioxo-1,4-dihydronaphthalen-2-yl)- N , N ,2-trimethylprop-2-enamide] (33).…”

DNA damage mediates changes in neuronal sensitivity induced by the inflammatory mediators, MCP-1 and LPS, and can be reversed by enhancing the DNA repair function of APE1

“…We demonstrate that peripheral inflammation induces DNA damage in the soma of neurons of the lumbar DRG and recapitulate this DNA damage in DRG cultures exposed to the inflammatory mediators, LPS or MCP-1. We also establish that DNA damage mediates changes in neuronal sensitivity, as determined by capsaicin-stimulated neuropeptide release by exogenously enhancing DNA repair via the overexpression of the enzyme APE1 and use of a small molecule APE1 DNA repair enhancer, E3330 (Vasko et al, 2011, Kelley et al, 2014, Georgiadis et al, 2016, Kelley et al, 2016). These data identify a novel pathway by which inflammatory mediators sustain changes in neuronal sensitivity and highlight the enhancement of neuronal DNA repair as a pharmacological target to alleviate inflammatory or chronic pain.…”

Ref-1/APE1 Inhibition with Novel Small Molecules Blocks Ocular Neovascularization

“…Although the lead clinical candidate is effective in preclinical cancer studies, we also sought novel, second generation Ref-1 inhibitors that would increase efficacy in antiangiogenic and anti-inflammatory transcription factor (NF-kB, HIF-1a) inhibition, as well as new chemical properties. We present here the synthesis of APX3330 derivatives APX2009 [reported previously as a neuroprotective agent (Kelley et al, 2016)], and APX2014 [reported here for the first time (Kelley and Wikel, 2015)]. We go on to show that these compounds have antiangiogenic activity against retinal and choroidal endothelial cells both in culture and in an ex vivo choroidal sprouting model.…”