Research Project
10326595
Neuropathic pain remains a challenging neurologic disorder that adversely affects quality of life and presents a large unmet medical need. Chemotherapy-induced peripheral neuropathy (CIPN) is a chronic, severely debilitating consequence of cancer therapy for which there are no effective management strategies. Upwards of 80-97% of CIPN patients reported using prescription opioids for this pain management. Mitochondrial dysfunction, oxidative stress, and inflammation have all been implicated in CIPN etiology. In a mouse model of paclitaxel-induced pain sensitivity, we have previously reported that cannabidiol (CBD) is effective in preventing the onset of this treatment consequence. Now a new CBD analogue (KLS-13019) has been discovered in our laboratory that has improved drug-like properties in comparison to CBD, while retaining neuroprotective properties. In our Phase 1 STTR, the previous neuroprotective effects of CBD to prevent the development of mechanical sensitivity in the presence of paclitaxel were confirmed and extended to the structural analogue KLS- 13019. Both compounds were equi-effective and equi-potent following oral administration. In the reversal studies, CBD did not attenuate mechanical sensitivity when administered after CIPN was induced by paclitaxel treatment. However, KLS-13019 significantly and dose-dependently attenuated tactile sensitivity in the reversal paradigm and was more potent and effective than treatment with morphine. Importantly, KLS-13019 also attenuated the reinforcing properties of morphine in a mouse model of morphine self-administration. In vitro, we have shown that KLS-13019 and CBD protect against paclitaxel-induced oxidative stress in dorsal root ganglia cultures, and that a mechanism underlying this neuroprotection is regulation of intracellular calcium via the mitochondrial Na+/Ca++ exchanger-1 (mNCX-1). Our central hypothesis is that administration of CBD or KLS-13019 preserves Ca2+ homeostasis by promoting activity of the mNCX-1. Furthermore, our new data demonstrates that the putative cannabinoid receptor GPR55 is induced following paclitaxel treatment and contributes to sensory neuron toxicity and inflammation that can be reversed by KLS-13019, but not CBD. These studies support a pro- nociceptive, pro-inflammatory role for GPR55 that mediates pain associated with CIPN. We predict bi-modal pharmacological effects of KLS-13019 that can both increase viability of sensory neurons exposed to paclitaxel acutely and decrease inducible GPR55 that contributes to long-term neuroinflammation. Evidence has been obtained that KLS-13019 is an antagonist to GPR55 as shown in a ?-arrestin assay. In Phase 2, we will optimize the process to prepare KLS-13019, develop analytical methods, optimize formulation, and evaluate in pharmacokinetic studies. A fully battery of genotoxicity, safety pharmacology, toxicokinetic, and toxicology reports will be completed. KLS-13019 will be evaluated in a rat models of CIPN, tolerance, impairment, and abuse liability. At the conclusion of this grant, the data will be submitted to the FDA and a pre-IND meeting will be completed.
