Stibium Metallicum Praeparatum D6 Versus Placebo in the Reduction of Paclitaxel-induced Peripheral Neurotoxicity

Chemotherapy-induced peripheral neuropathy (CIPN) is one of the most limiting side effects of chemotherapy and often leads to adaptations in the administration of the chemotherapy, including dose reduction or even discontinuation of treatment. In general, the symptoms of CIPN are sensory, often occuring in a "stocking and glove" manner, and most commonly including tingling, numbness, and dysaesthesia. In addition, patients treated with agents inducing CIPN, such as taxanes or platinum compounds, also may experience motor symptoms, which often present as distal or general weakness, and autonomic nervous system dysfunction (e.g. constipation or diarrhea, abnormalities of sweating, and lightheadedness and/or dizziness with positional changes). Furthermore, patients with chronic symptoms report having unsteady gait, putting them at higher risk of falling. CIPN has a largest impact on quality of life and is associated with the development of psychological distress. Cancer survivors' report long-term peripheral neuropathy symptoms with impact on symptom burden, functional status, and quality of life. Because of the growing prevalence of cancer and of cancer survivors, the lack of adequate treatment or preventive strategies against CIPN, as well as the major societal and economic costs, CIPN is becoming a major issue.

According to the National Comprehensive Cancer Network (NCCN) task force report, the overall incidence of CIPN ranges from 57 up to 83% of patients treated with paclitaxel. The incidence and prevalence of CIPN vary among neurotoxic agents, dosing regimens (intensity and cumulative dosing), regimen selection (e.g. combination taxanes and platinum compounds), as well as in presence of preexisting neuropathy, comorbidities and genetic susceptibility. The analysis of the Japanese Adverse Drug Event Report database showed that more than 50% of CIPN associated with taxanes and platinum compounds occurred within four weeks.

After completion of chemotherapy, the prevalence of CIPN for neurotoxic chemotherapy overall one month after finishing chemotherapy is 68%, dropping to 60% at 3 months and 30% at 6 months or more. Severe symptoms are likely to persist longer. In patients treated with taxanes, nearly half of patients have symptoms 6 to 9 months after completing chemotherapy, and many require years to recover, if they recover at all. In early-stage breast cancer patients treated with paclitaxel, persistent numbness one year after treatment with paclitaxel were reported in approximately 67% to 80% of early-stage breast cancer patients. Two years after the end of therapy, 34.4% of breast cancer patients treated with paclitaxel reported neuropathy symptoms, with 18.0% reporting more severe symptoms. Another study showed that two or more years after diagnosis, 44% of breast cancer survivors treated with paclitaxel reported long-term neuropathy symptoms.

Current management of CIPN (i.e. prevention and treatment) includes dose reduction, delay of chemotherapy cycles, or treatment discontinuation. This reduces the chance of an effective cancer treatment.

The 2014, 2020, and 2021 American Society of Clinical Oncology (ASCO) Guidelines on the Prevention and Management of Chemotherapy-Induced Peripheral Neuropathy did not recommend any agent for the prevention of CIPN, and have cautiously recommended treatment of existing CIPN with duloxetine. Preliminary evidence suggests a potential benefit from non-pharmacological treatments in the prevention and/or treatment of chronic neuropathy including exercise, acupuncture, cryotherapy, compression therapy, and scrambler therapy. Larger sample-sized definitive studies are needed to confirm efficacy and clarify risks of these interventions.

Cumulative dose is a strong risk factor for the development of CIPN. Other risk factors include dose per cycle, treatment schedule (number of injections), duration of infusion, prior or concomitant chemotherapy with neurotoxic agents (i.e. vinca alkaloids, taxanes, platinum compounds, epothilones including ixabepilone, bortezomib, thalidomide, arsenice trioxides), development and severity of acute neuropathy syndrome or acute pain syndrome within 1 to 4 days following the neurotoxic agent infusion, comorbid health conditions associated with an increased risk of neuropathy (i.e. diabetes mellitus, excess alcohol, HIV, smoking, decreased creatinine clearance, folate/vitamin B12 deficiency), pre-existing peripheral neuropathy, older age, and higher body mass index. Other clinical risk factors such as sedentary behavior, insomnia, fatigue, anxiety, and depression have been shown to increase CIPN prevalence. Genetic factors may also be associated with risk of developing CIPN.

Due to the scarcity of drugs that are effective for preventing and treating CIPN, the distress of patients who suffer from CIPN, and the major societal and economic costs, new approaches and effective treatment strategies are required. This study investigates the efficacy and tolerance of Stibium metallicum praeparatum D6 (Weleda), also known as Antimon, to reduce paclitaxel-induced peripheral neuropathy as reported by patients. As secondary outcomes, the influence on quality of life as well as on chemotherapy treatment adherence and dose of chemotherapy delivered is assessed.