A Double Blind, Randomized, Placebo Controlled, Parallel Group Dose-range Exploration Study of Sativex® in Relieving Pain in Patients With Advanced Cancer, Who Experience Inadequate Analgesia During Optimized Chronic Opioid Therapy.

Inclusion Criteria:

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

- The patient is able (in the investigators opinion) and willing to comply with all
study requirements.

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

- The patient is receiving a sustained release (SR) fixed dose of opioid therapy
(excluding Methadone). N.B. The opiate therapy must be Step III according to the
World Health Organization (WHO) analgesic ladder.

- The patient is willing to continue to take their regular daily baseline opioid
regimen (SR) at the same dose, throughout the duration of study.

Exclusion Criteria:

- The patient should be excluded from entering study if they have received or are due
to receive during the study period; chemotherapy, hormone therapy or radiotherapy,
which, in the opinion of the investigator will affect their pain.

- Any history or immediate family history of schizophrenia, other psychotic illness,
severe personality disorder or other significant psychiatric disorder other than
depression associated with their underlying condition.

- Any known or suspected history of a diagnosed dependence disorder, current heavy
alcohol consumption, current use of an illicit drug or current non prescribed use of
any prescription drug.

- The patient has poorly controlled epilepsy or recurrent seizures (i.e. at least one
year since last seizure).

- The patient has experienced myocardial infarction or clinically relevant 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 relevant arrhythmia
or myocardial infarction.