Mamet Julien, Harris Scott, Klukinov Michael, Yeomans David C, Donahue Renee R, Taylor Brad K, Eddinger Kelly, Yaksh Tony, Manning Donald C
1 Adynxx, Inc., CA, USA.
2 Department of Anesthesia, Stanford University, CA, USA.
Mol Pain. 2017 Jan;13:1744806917703112. doi: 10.1177/1744806917703112.
Background AYX1 is an unmodified DNA-decoy designed to reduce acute post-surgical pain and its chronification with a single intrathecal dose at the time of surgery. AYX1 inhibits the transcription factor early growth response protein 1, which is transiently induced at the time of injury and triggers gene regulation in the dorsal root ganglia and spinal cord that leads to long-term sensitization and pain. This work characterizes the AYX1 dose-response profile in rats and the link to AYX1 pharmacokinetics and metabolism in the cerebrospinal fluid, dorsal root ganglia, and spinal cord. Results The effects of ascending dose-levels of AYX1 on mechanical hypersensitivity were measured in the spared nerve injury model of chronic pain and in a plantar incision model of acute post-surgical pain. AYX1 dose-response profile shows that efficacy rapidly increases from a minimum effective dose of ∼ 0.5 mg to a peak maximum effective dose of ∼ 1 mg. With further dose escalation, the efficacy paradoxically appears to decrease by ∼ 30% and then returns to full efficacy at the maximum feasible dose of ∼ 4 mg. The reduction of efficacy is associated to doses triggering a near-saturation of AYX1 metabolism by nucleases in the cerebrospinal fluid and a paradoxical reduction of AYX1 exposure during the period of early growth response protein 1 induction. This effect is overcome at higher doses that compensate for the effect of metabolism. Discussion AYX1 is a competitive antagonist of early growth response protein 1, which is consistent with the overall increased efficacy observed as dose-levels initially escalate. Chemically, AYX1 is unprotected against degradation by nucleases. The sensitivity to nucleases is reflected in a paradoxical reduction of efficacy in the dose-response curve. Conclusions These findings point to the importance of the nuclease environment of the cerebrospinal fluid to the research and development of AYX1 and other intrathecal nucleotide-based therapeutics.
AYX1是一种未经修饰的DNA诱饵，旨在通过手术时单次鞘内给药减轻术后急性疼痛及其慢性化。AYX1抑制转录因子早期生长反应蛋白1，该蛋白在损伤时短暂诱导，并触发背根神经节和脊髓中的基因调控，导致长期致敏和疼痛。这项工作描述了AYX1在大鼠中的剂量反应曲线以及与脑脊液、背根神经节和脊髓中AYX1药代动力学和代谢的联系。结果：在慢性疼痛的 spared 神经损伤模型和急性术后疼痛的足底切口模型中测量了递增剂量水平的AYX1对机械性超敏反应的影响。AYX1剂量反应曲线表明，疗效从约0.5毫克的最小有效剂量迅速增加到约1毫克的峰值最大有效剂量。随着剂量进一步增加，疗效反而似乎降低了约30%，然后在约4毫克的最大可行剂量时恢复到完全疗效。疗效降低与脑脊液中核酸酶触发AYX1代谢接近饱和的剂量以及早期生长反应蛋白1诱导期间AYX1暴露的反常降低有关。在较高剂量下这种效应被克服，这些高剂量补偿了代谢的影响。讨论：AYX1是早期生长反应蛋白1的竞争性拮抗剂，这与随着剂量水平最初增加而观察到的总体疗效增加一致。从化学角度来看，AYX1对核酸酶降解没有保护作用。对核酸酶的敏感性反映在剂量反应曲线中疗效的反常降低上。结论：这些发现指出了脑脊液核酸酶环境对AYX1和其他鞘内核苷酸类治疗药物研发的重要性。
