Inclusion Criteria:
1. Participant has voluntarily agreed to study participation by giving written informed consent and must be ≥18 years of age on the day of signing the informed consent form (ICF).
2. Participant has advanced solid malignant tumors not amenable to curative-intent therapy (locally advanced unresectable or metastatic).
3. Participant life expectancy is ≥3 months at screening according to investigator's best judgement.
4. Participant has a clinical diagnosis of moderate to severe cancer-related pain with average daily pain score to be ≥4 for at least 4 out of the 7-day screening period, despite ongoing opioid treatment, as evidenced by their response to the BPI-SF Question #5 on the Numeric Rating Scale (NRS).
5. Participant is taking a stable dose of opioid therapy (Step III according to the World Health Organization \[WHO\] analgesic ladder) for at least 1 week prior to screening to relieve cancer-related pain.
6. Participant has adequate organ function, as indicated by the following laboratory values, at screening:
1. Baseline serum electrolytes must be within the normal range per local laboratories (for baseline serum electrolytes that are out of range, these may be corrected, and the potential participant may be rescreened).
2. Stable renal function (estimated glomerular filtration rate \[eGFR\] \>15).
3. Total bilirubin (TBIL) ≤1.5 x upper limit of normal (ULN); or ≤3 x ULN for participants with Gilbert's syndrome.
4. Aspartate aminotransferase (AST) and alanine aminotransferase (ALT) ≤3 x ULN or ≤5 x ULN for participants with liver metastases.
7. Participant has stable cardiac function, as determined by:
1. No clinically significant ECG waveform abnormalities.
2. QT interval corrected for heart rate using Fridericia's formula (QTcF) ≤470 msec, as determined by the mean QTcF values from the ECG assessments at screening (one triplicate).
8. Participant can tolerate oral medications including capsules.
9. Participant is willing to take a medication which may exhibit psychoactive effects.
10. Participant must discontinue the use of the following medications 7 days before the start of study intervention and for the duration of the trial, unless in the opinion of the investigator and sponsor, the medication will not interfere with the study: herbal supplements or related products which are cytochrome P450 (CYP) 2E1, CYP3A4, or P-glycoprotein substrates, or which are strong inhibitors of the CYP3A4 and/or CYP3A5 pathways or which are known CYP3A4 inducers (this includes grapefruit and Seville oranges juice or related products, and St. John's wort).
11. Participant must not engage in medicinal or recreational use of any cannabinoid containing substance, in any form, within 30 days prior to screening and be willing to abstain from medicinal or recreational use of cannabis and other cannabinoid compounds (other than the Investigational Product) for the duration of the study.
12. Participant must have a negative urine drug screen for cannabinoids at screening and prior to dosing at Day 1; one repeat test may be conducted for a suspected false positive result.
13. Participant must not have any current or past allergic or adverse reaction or known sensitivity to olive oil, gelatine, glycerin, and titanium dioxide, or to cannabinoid-like substances (including but not limited to dronabinol, marinol, nabilone, marijuana, cannabis, THC, or cannabinoid oil).
14. Female participants are eligible to enter and participate in the study if they are of:
1. Non-childbearing potential.
2. Childbearing potential with a negative serum pregnancy test at screening (within 7 days of the first dose of Investigational Product) and agree to use contraception before study entry and throughout the study until 3 months after the last administered dose of the Investigational Product.
15. Male participants are eligible to enter and participate in the study if they are vasectomized or agree to the use of contraception during the study treatment period and for at least 3 months after the last administered dose of the Investigational Product.
16. Participants, in the opinion of the investigator, should understand the nature of the study, be able to participate in all planned assessments, complete all required tests, and be likely to comply with all study procedures.
Exclusion Criteria:
1. Female participants who are pregnant or lactating.
2. Participant has uncontrolled psychiatric disorders (severe depression or anxiety, personality disorder, psychosis, or schizophrenia).
3. Participant has a family history of schizophrenia.
4. Participant has current or history of suicidal behavior or ideation assessed by Columbia-Suicide Severity Rating Scale (C-SSRS).
5. Participant has any known or suspected history of a diagnosed dependency disorder, including opioid abuse, current heavy alcohol consumption (i.e. more than 10 units of alcohol per week or 4 units on any given day \[1 unit = 150 mL of wine, 260 mL of beer, or 45 mL of 40% alcohol\]), current use of an illicit drug or current non-prescribed use of any prescription drug (Alcohol, Smoking and Substance Involvement Screening Test \[ASSIST\]).
6. Participant has engaged in medicinal or recreational use of any cannabinoid containing substance, in any form within the 30 days prior to screening.
7. Participant is within the first cycle of a new line of anticancer therapy (including but not limited to chemotherapy or other systemic anticancer therapies, immunotherapy, radiation therapy, or surgery) at the start of the screening period.
8. Participant has had any major surgery within 4 weeks prior to screening.
9. Participant has an active infection requiring systemic treatment at the start of the study treatment.
10. Participant has cirrhosis or severe hepatic impairment defined as AST and ALT \>3 x ULN or \>5 x ULN for participants with liver metastases.
11. Participant has any of the following cardiovascular criteria:
a. Current evidence of unstable angina or another form of symptomatic cardiac ischemia b. Acute myocardial infarction ≤3 months prior to screening c. Heart failure of New York Heart Association Classification III or IV ≤3 months prior to screening d. Grade ≥2 ventricular arrhythmia ≤3 months prior to screening e. Cerebrovascular Accident (CVA) or Grade ≥2 Transient Ischemic Attack (TIA) ≤6 months prior to screening f. Grade ≥2 hypertension that cannot be managed by standard anti-hypertension medications before initiation of treatment g. Syncope or seizure ≤3 months before screening.
12. Participant has a history or presence of gastrointestinal disease or other condition known to interfere with the absorption of drugs.
13. Participant has intractable vomiting.
14. Participant has any other condition or abnormality that, in the investigator's judgement after medical interview, physical examination, and/or screening and baseline investigations, renders participant unfit for the study or precludes the participant's safe participation in and completion of the study.
15. Participant has concurrent participation in another therapeutic clinical trial or participation in another clinical trial within 30 days prior to the enrolment in this trial.
