Some patients receiving taxane-based chemotherapy experience numbness, tingling, or pain in their hands and feet, known as chemotherapy-induced peripheral neuropathy (CIPN). This study aims to find out whether oral mecobalamin can prevent or reduce CIPN. Participants will be assigned to take mecobalamin or to receive no routine mecobalamin prevention during chemotherapy, and outcomes will be compared between groups.

This is a prospective, multicenter, open-label randomized controlled trial to evaluate oral mecobalamin for the prevention of chemotherapy-induced peripheral neuropathy (CIPN) in patients with solid tumors receiving taxane-based chemotherapy. Participants are assigned to receive prophylactic mecobalamin (0.5 mg orally three times daily, starting on the first day of taxane-based chemotherapy and continuing until chemotherapy completion) or no routine mecobalamin prophylaxis. The primary endpoint is the cumulative incidence of grade ≥2 CIPN (CTCAE v6.0) from randomization to the end of chemotherapy.

Secondary endpoints include measures of CIPN onset and severity, patient-reported outcomes (PROs), chemotherapy delivery, and safety. Study assessments are conducted at baseline and during each chemotherapy cycle.

Inclusion Criteria:

1. Histologically or cytologically confirmed solid tumors, including but not limited to breast cancer, lung cancer, gastric cancer, cervical cancer, endometrial cancer, ovarian cancer, pancreatic cancer, and melanoma;
2. Age ≥18 years;
3. Scheduled to receive adjuvant or neoadjuvant taxane-based chemotherapy (including paclitaxel, nab-paclitaxel, or docetaxel; as monotherapy or in combination) for early-stage disease, or has advanced disease with no prior chemotherapy;
4. Life expectancy ≥3 months;
5. ECOG performance status 0-2;
6. Adequate major organ function (cardiac, hepatic, renal, and bone marrow function);
7. Willing and able to provide written informed consent and comply with study procedures.

Exclusion Criteria:

1. Severe impairment of major organ function such that the participant cannot tolerate standard-dose chemotherapy;
2. Pre-existing peripheral neuropathy or a history of peripheral neuropathy;
3. Skin conditions (e.g., severe palmoplantar keratoderma, active skin infection) that may interfere with assessment of CIPN symptoms;
4. Recent use of medications that may alleviate CIPN symptoms;
5. Inability to swallow, intestinal obstruction, or other conditions that may affect drug absorption;
6. Known hypersensitivity or allergy to mecobalamin;
7. Pregnant or breastfeeding women.

De-identified individual participant data (IPD) that underlie the results reported in publications will be shared with qualified researchers upon reasonable request. Shared IPD will include participant-level data on baseline characteristics, treatment exposure, primary and secondary outcome measures, and safety outcomes. Requests must include a scientifically sound research proposal and analysis plan. Access will be granted after approval by the study steering committee and completion of a data use agreement.

Beginning after publication of the primary results and available for 3 years.

De-identified IPD and supporting documents will be made available to qualified researchers upon submission of a scientifically valid research proposal to the corresponding author. Access requires approval by the study steering committee and the completion of a data use agreement to ensure appropriate data use and participant confidentiality.