Botulinum Toxin A for the Treatment of Chemotherapy Induced Peripheral Neuropathy

Chemotherapy induced peripheral neuropathy (CIPN) is a common side effect of taxanes and platinum derivative based chemotherapeutic agents, common in breast cancer treatment regimens. It can have a significant effect on both quality of life and treatment outcomes, often resulting in dose modifications and early treatment discontinuation. The use of IncobotulinumtoxinA (INA) ((Xeomin®, Merz) has recently been shown to be effective in the treatment of neuropathic pain via inhibiting the release of several neurotransmitters involved in pain signaling pathway. The purpose of this study is to examine the efficacy and safety of intradermal INA injections for treatment of CIPN in breast cancer patients. The study will recruit a total of 40 participants, randomly assigned to receive either INA (Experimental group, n=20) or saline placebo injections (Control group n=20). Potential participants who have received chemotherapy for breast cancer will be screened for the diagnosis of peripheral neuropathy. After obtaining informed consent, participants will be further screened with the DN4 questionnaire, a clinician administered questionnaire that has a high level of sensitivity and specificity in discriminating neuropathic pain. Those study participants who score ≥4 on this tool will undergo nerve conduction studies to confirm the presence of peripheral neuropathy. Recruited study participants will then be randomized to treatment or control groups; the treatment group will undergo intradermal injections of INA (100 Units INA, total volume 5ml), and the control groups will undergo placebo injection with preservative-free normal saline (equal volume, 5mL). Total injection volume will be divided evenly and injected intradermally into a total of 50 sites on either the feet or hands (25 sites per limb). The primary outcome will be the assessment of pain using the neuropathic pain scale (NPS) prior to intervention and at eight weeks post intervention. Secondary outcomes will include the change in NPS for each domain at additional time points: 2weeks, 4 weeks, 12 weeks, 6 months, the change in the Neuropathic Pain Impact on Quality of Life (NePIQoL) score at time points: 2 weeks, 4 weeks, 8 weeks, 12 weeks, 6 months, and the incidence of treatment related adverse events within each cohort. Statistical analysis will be utilized to determine whether the injection of intradermal INA is effective in improving pain as measured by the NPS scales vs placebo. We hypothesize that the study participants treated with INA will have lower NPS scores as compared to placebo.