The goal of this clinical trial is to learn if a commercially available cannabigerol (CBG)/cannabidiol (CBD) oil is safe, feasible to use, and can help reduce symptoms of chemotherapy-induced peripheral neuropathy (CIPN) in adults who have completed platinum-based chemotherapy for gastrointestinal cancers. The main questions it aims to answer are:

Is CBG/CBD oil safe and well-tolerated over a 12-week treatment period?

Can participants with CIPN use CBG/CBD oil consistently as part of their care?

Does CBG/CBD oil help reduce pain, numbness, or other symptoms of CIPN?

Participants will:

Take CBG/CBD oil under the tongue (sublingually) twice daily for 12 weeks

Complete regular symptom assessments and functional tests during study visits

Provide blood samples for cannabinoid and metabolite level testing

This pilot clinical trial is designed to evaluate the safety, feasibility, and preliminary efficacy of a commercially available cannabigerol (CBG)/cannabidiol (CBD) oil in treating chemotherapy-induced peripheral neuropathy (CIPN) in adult patients who have completed platinum-based chemotherapy for gastrointestinal malignancies. The study is based on preclinical findings from Dr. Wesley Raup-Konsavage's laboratory, which showed that CBG and CBD reduced neuropathic pain in animal models of CIPN. This clinical trial seeks to translate these findings into a patient population with persistent CIPN symptoms.

The study intervention uses a high-CBG/CBD hemp oil extract that is marketed as a dietary supplement and contains a verified profile of cannabinoids and terpenes. The formulation also includes small amounts of cannabichromene (CBC), which may contribute to analgesic effects via the "entourage effect." Subjects will administer 0.5 mL sublingually twice daily during the first week, followed by 1 mL sublingually twice daily for the remaining 11 weeks of the 12-week treatment period.

The treatment period is divided into three 4-week cycles to structure visit scheduling and assessments. The study will collect data on symptom changes, physical function, mental health, tolerability, and cannabinoid levels over time.

Primary objectives include evaluating the safety and tolerability of CBG/CBD oil and the feasibility of its use in this patient population. Secondary objectives include measuring changes in CIPN symptoms, physical and mental function, adherence, pharmacological tolerance, and circulating cannabinoid/metabolite levels.

The study addresses an urgent need for effective treatments for CIPN, as current therapies (e.g., duloxetine, gabapentin, NSAIDs) are often inadequate and poorly tolerated. By assessing a hemp extract rather than a purified compound, this study also explores the broader applicability and real-world relevance of cannabinoid-based supplements for supportive cancer care.

Inclusion Criteria:

• Adults aged 21 years or older.
• Patients with grade 1 or greater CIPN symptoms, such as neuropathic pain, paresthesia, or muscle weakness, persisting for more than 2 weeks as defined by the National Cancer Institute (NCI) Common Toxicity Criteria for Adverse Events (CTCAE) version 5.
• Patients who have completed platinum-based chemotherapy for colorectal carcinoma, biliary tract carcinoma, pancreatic carcinoma, esophageal carcinoma, gastric carcinoma, or small intestinal carcinoma within the past 2 years.
• Patients currently taking any treatment for CIPN must discontinue such treatments at least 2 weeks prior to enrollment.
• Women of childbearing potential (WOCBP): negative urine or serum pregnancy test. If the urine test is positive or cannot be confirmed as negative, a serum pregnancy test will be required (A pregnancy teste will be performed during screening (up to 28 days before treatment and repeated within 7 days prior to study drug initiation to confirm baseline status and minimize risk of unrecognized pregnancy).
• Agreement by females and males of childbearing potential to use an effective method of birth control or abstain from heterosexual activity for the course of the study through at least 1 months after the last dose of protocol therapy. Childbearing potential defined as not being surgically sterilized (men and women) or have not been free from menses for > 1 year (women only).
• Patients from Penn State Health.

Exclusion Criteria:

• Patients under the age of 21 years.
• Patients with a history of preexisting neuropathy prior to chemotherapy.
• Pregnant and nursing women.
• Patients with hypertension that, in the investigator's judgement, is uncontrolled despite the use of anti-hypertensives, or with hypotension (systolic blood pressure <90 mmHg and/or diastolic blood pressure <60 mmHg).
• History of or active arterial thromboembolic event (e.g. stroke, myocardial infarction).
• Patients who have used an investigational drug within 30 days prior to the screening visit or are currently participating in another interventional investigational study.
• Patients who have liver function tests AST/ALT > 3 times above the upper limits of normal (ULN) in the past year.
• Patients who have suicidal ideation or uncontrolled depression within the past year.
• Patients with known sensitivity to any components of CBG/CBD hemp extract.
• Patients with known sensitivity to coconut oil.
• Patients currently receiving active systemic anti-cancer therapies, including but not limited to chemotherapy, immunotherapy, targeted therapy (e.g., tyrosine kinase inhibitors, anti-HER2 therapy), or any other ongoing systemic treatment intended to control or reduce tumor burden.
• Current use of moderate or strong inhibitors or inducers of CYP3A4 or CYP2C19.
• Current use of sensitive CYP2C19 substrates with narrow therapeutic indices (e.g., diazepam, clobazam), unless the subject's primary physician agrees to adjust the dose and provide close therapeutic monitoring.
• Current use of valproate or other medications known to significantly increase the risk of liver enzyme elevations when co-administered with cannabidiol.
• Current use of medications that are primarily metabolized by CYP1A2 (e.g., theophylline) or CYP2B6 (e.g., bupropion, efavirenz) that cannot be safely monitored or dose-adjusted per the discretion of the study investigator. Occasional or dietary caffeine intake is permitted.
• Current use of medications that are substrates of UGT1A9 (e.g., diflunisal, propofol, fenofibrate), UGT2B7 (e.g., gemfibrozil, lamotrigine, morphine, lorazepam), CYP2C8, or CYP2C9 (e.g., phenytoin) that cannot be safely monitored or dose-adjusted per the discretion of the study investigator.
• Current use of other known hepatotoxic drugs unless the potential risk has been evaluated and deemed acceptable by the study investigator.