Evaluation of Treatment Patterns and Direct Costs Associated with the Management of Neuropathic Pain

Neurodynamic Treatment Promotes Mechanical Pain Modulation in Sensory Neurons and Nerve Regeneration in Rats

Background: Somatic nerve injuries are a rising problem leading to disability associated with neuropathic pain commonly reported as mechanical allodynia (MA) and hyperalgesia. These symptoms are strongly dependent on specific processes in the dorsal root ganglia (DRG). Neurodynamic treatment (NDT), consisting of selective uniaxial nerve repeated tension protocols, effectively reduces pain and disability in neuropathic pain patients even though the biological mechanisms remain poorly characterized. We aimed to define, both in vivo and ex vivo, how NDT could promote nerve regeneration and modulate some processes in the DRG linked to MA and hyperalgesia. Methods: We examined in Wistar rats, after unilateral median and ulnar nerve crush, the therapeutic effects of NDT and the possible protective effects of NDT administered for 10 days before the injury. We adopted an ex vivo model of DRG organotypic explant subjected to NDT to explore the selective effects on DRG cells. Results: Behavioural tests, morphological and morphometrical analyses, and gene and protein expression analyses were performed, and these tests revealed that NDT promotes nerve regeneration processes, speeds up sensory motor recovery, and modulates mechanical pain by affecting, in the DRG, the expression of TACAN, a mechanosensitive receptor shared between humans and rats responsible for MA and hyperalgesia. The ex vivo experiments have shown that NDT increases neurite regrowth and confirmed the modulation of TACAN. Conclusions: The results obtained in this study on the biological and molecular mechanisms induced by NDT will allow the exploration, in future clinical trials, of its efficacy in different conditions of neuropathic pain.

CCR1 enhances SUMOylation of DGCR8 by up-regulating ERK phosphorylation to promote spinal nerve ligation-induced neuropathic pain

Neuropathic pain is a somatosensory nervous system dysfunction that remains a threatening health problem globally. Recent studies have highlighted the involvement of C-C motif chemokine receptor 1 (CCR1) in neuropathic pain. Herein, the current study set out to explore the modulatory role of CCR1 in spinal nerve ligation (SNL)-induced neuropathic pain and its underlying molecular mechanism. First, it was found that CCR1 was highly expressed in spinal cord tissues and microglial cells of SNL rats. On the other hand, CCR1 knockdown attenuated nerve pain in SNL rats and repressed microglial cell activation in SNL rats and also in the LPS-induced microglial cell model of nerve injury, as evidenced by elevated microglial cell markers OX-42 and IL-1β, IL-6 and TNF-α. Mechanistically, CCR1 enhanced small ubiquitin-like modifier 1 (SUMO1) modification of DiGeorge syndrome critical region gene 8 (DGCR8) in LPS-treated microglial cells by phosphorylating ERK. Moreover, CCR1 silencing brought about elevations in mechanical withdrawal threshold and thermal withdrawal latency. To conclude, our findings indicated that CCR1 enhanced the modification of DGCR8 by SUMO1 through phosphorylation of ERK, thereby promoting the activation and inflammatory response of spinal cord microglial cells and increasing the sensitivity of SNL rats to pain. Thus, this study offers a promising therapeutic target for the management of neuropathic pain.

Results of two Phase 1, Randomized, Double-blind, Placebo-controlled, Studies (Ascending Single-dose and Multiple-dose Studies) to Determine the Safety, Tolerability, and Pharmacokinetics of Orally Administered LX9211 in Healthy Participants

PURPOSE

For neuropathic pain, current therapies do not provide relief for most patients; less than half achieve a 50% pain reduction. Current analgesics have adverse effects. We present 2 Phase I studies of LX9211, a new small-molecule AP2-associated kinase 1 inhibitor with preclinical effectiveness in pain relief.

METHODS

Both randomized, placebo-controlled studies' primary objectives evaluated the tolerability and pharmacokinetic properties of oral LX9211. In the single-ascending dose (SAD) study, single, oral, liquid doses of 5, 10, 15, 20, 30, 40, 80, 120, 160, 200, and 300 mg of LX9211 or placebo were administered in the fasted state and 40 mg in a fed group. In the multiple-ascending dose (MAD) study, a loading dose was administered on day 1 and maintenance doses were administered daily on days 2 to 14. The treatment groups were designated as: 25/2.5, 50/5.0, 100/10, 150/15, and 200/20 mg. The secondary objectives included ECG evaluation.

FINDINGS

The SAD study enrolled 96 participants 19 to 61 years of age (86.5% male) in 12 cohorts (2:6 placebo:LX9211), and the MAD study enrolled 50 participants 20 to 63 years of age (78% male) in 5 cohorts (2:8 placebo:LX9211). Both studies had a good LX9211 safety profile. No deaths or serious adverse events occurred. All treatment-emergent adverse events (TEAEs) were mild, except for moderate nausea and vomiting reported in 1 participant in the SAD 300-mg cohort. All TEAEs were considered recovered or resolved, except for blurred vision (n = 1 in the SAD 300-mg group), which was ongoing at the last visit. One participant in the MAD study (50/5 mg group) discontinued participation in the study early because of TEAEs (angioedema, dermatitis allergic, and urticaria). Headache, dizziness, constipation, and nausea were the most common TEAEs. In the SAD study, 4 participants in the 200-mg cohort developed headache approximately 24 hours after dosing, lasting 24 to 48 hours. Only 1 required treatment (acetaminophen). No notable ECG changes from baseline were found in either study. After both single- and multiple-dose administration, plasma exposure of LX9211 was approximately dose proportional. Steady-state LX9211 plasma concentrations were rapidly attained and maintained by a dosing regimen of a loading dose, followed by daily maintenance doses (1/10 the loading dose). No accumulation was as seen after multiple dosing.

IMPLICATIONS

These studies found that LX9211 was safe and well tolerated in healthy participants. These findings suggest it is appropriate to take LX9211 forward into Phase II studies of patients with diabetic peripheral neuropathic pain and postherpetic neuralgia. LX9211 has received fast track designation by the US Food and Drug Administration.