Inclusion Criteria:

- The patient has advanced cancer for which there is no known curative therapy

- The patient has a clinical diagnosis of cancer related pain, which is not alleviated
with their current optimized opioid treatment

- The patient is receiving an optimized maintenance dose of Step III opioid therapy,
preferably with a sustained release preparation, but also allowing a regular
maintenance dose of around the clock use of immediate release preparations

- The patient is receiving a daily maintenance dose Step III opioid therapy of less
than or equal to a total daily opioid dose of 500 mg/day of morphine equivalence
(including maintenance and break-through opioids)

- The patient is using no more than one type of break-through opioid analgesia

Exclusion Criteria (abbreviated):

- Have any planned clinical interventions that would affect their pain (e.g.,
chemotherapy or radiation therapy where, in the clinical judgment of the
investigator, these would be expected to affect pain)

- The patient is currently using or has used cannabis or cannabinoid based medications
within 30 days of study entry and is unwilling to abstain for the duration of the
study

- Has experienced myocardial infarction or clinically significant cardiac dysfunction
within the last 12 months or has a cardiac disorder that, in the opinion of the
investigator would put the patient at risk of a clinically significant arrhythmia or
myocardial infarction

- Has significantly impaired renal function

- Has significantly impaired hepatic function

- Female patients of child-bearing potential and male patients whose partner is of
child-bearing potential, unless willing to ensure that they or their partner use
effective contraception, for example, oral contraception, double barrier,
intra-uterine device, during the study and for three months thereafter (however, a
male condom should not be used in conjunction with a female condom as this may not
prove effective)