Clinical research in chemotherapy-induced peripheral neuropathy: How, what, and when

One-year incidence of chemotherapy-induced peripheral neuropathy in oxaliplatin- or taxane-based chemotherapy: a multicenter, prospective registry study (MiroCIP study)

BACKGROUND

Chemotherapy-induced peripheral neuropathy (CIPN) and its associated pain negatively affect patient outcomes and quality of life (QoL). The two-part MiroCIP study included interventional and prospective observational studies. Here, we report the latter, describing CIPN incidence, risk factors, and outcomes.

RESEARCH DESIGN AND METHODS

This 1-year, multicenter, prospective registry study (May 2021-April 2023) included patients aged ≥ 20 years with colorectal, gastric, non-small cell lung, or breast cancer who were scheduled to undergo chemotherapy with oxaliplatin or taxane. The primary endpoint was Grade ≥ 2 sensory CIPN incidence within 12 months after chemotherapy initiation. Subjective and objective symptoms, QoL, and pain were evaluated.

RESULTS

Overall, 216 patients (female, 64.4%; mean age, 60.3 years) were included. Ninety-one (42.1%) and 131 (60.6%) patients received oxaliplatin- and taxane-based chemotherapy, respectively (six received both and were included in both groups). Grade ≥ 2 CIPN occurred in 96 patients (44.4%; 72.8/100 person-years), with 70.8% (68/96 patients) developing symptoms within 90 days. The most prominent CIPN symptoms were limb numbness/tingling and decreased vibration sensibility. No clinically meaningful risk factors were identified.

CONCLUSIONS

We clarified CIPN incidence in cancer patients. Subjective symptoms (limb numbness/tingling, decreased vibration sensibility) and pain are important CIPN symptoms requiring careful monitoring.

TRIAL REGISTRATION

jRCTs031210101.

Dysregulation of EAAT2 and VGLUT2 Spinal Glutamate Transports via Histone Deacetylase 2 (HDAC2) Contributes to Paclitaxel-induced Painful Neuropathy

Effective treatments for chemotherapy-induced peripheral neuropathy (CIPN) remain unavailable. Given the significance of spinal cord glutamate transporters in neuronal plasticity and central sensitization, this study investigated the role of excitatory amino acid transporter 2 (EAAT2) and vesicular-glutamate transporter 2 (VGLUT2) in the development of paclitaxel-induced painful neuropathy. Paclitaxel (2 mg/kg, i.p., cumulative dose 8 mg/kg) induced long-lasting mechanical allodynia (>28 days) with increased glutamate concentration and decreased EAAT2 expression with no changes in GABA/glycine or VGAT (vesicular GABA transporter) in rat spinal dorsal horn. VGLUT2 expression was upregulated and coexpressed with enhanced synaptophysin, characterizing nociceptive afferent sprouting and new synapse formation of glutamatergic neurons in the spinal cord dorsal horn. HDAC2 and transcription factor YY1 were also upregulated, and their interaction and colocalization were confirmed following paclitaxel treatment using co-immunoprecipitation. Inhibition or knockdown of HDAC2 expression by valproic acid, BRD6688, or HDAC2 siRNA not only attenuated paclitaxel-induced mechanical allodynia but also suppressed HDAC2 upregulation, glutamate accumulation, and the corresponding changes in EAAT2/VGLUT/synaptophysin expression and HDAC2/YY1 interaction. These findings indicate that loss of the balance between glutamate release and reuptake due to dysregulation EAAT2/VGLUT2/synaptophysin cascade in the spinal dorsal horn plays an important role in the development of paclitaxel-induced neuropathic pain. HDAC2/YY1 interaction as a complex appears essential in regulating this pathway, which can potentially be a therapeutic target to relieve CIPN by reversing central sensitization of spinal nociceptive neurons.