Otsuka Pharmaceutical, which has licensed the US commercialization rights to the product, will fund the clinical program.
GW R&D director Stephen Wright said, "This clinical development programme, being performed in partnership with Otsuka, is the largest ever undertaken by GW."
The trials are designed to obtain approval in the indication from the FDA in the US, and GW will also use the data for future regulatory applications in the indication in Europe and around the world.
The company’s previously announced two pivotal 380 patient Phase III cancer pain studies, which are proceeding on track, are expected to complete recruitment around the end of 2013.
Upon completion of these two studies, the company anticipates making regulatory filings.
The third trial, a supportive study, exposes patients to Sativex in a single blind phase of two weeks duration, following which responders will be randomized either to stay on Sativex or switch to placebo in a double blind phase for a five week treatment period.
The mean change from baseline in Phase B as measured using a 0-10 Numeric Rating Scale (NRS) is the primary efficacy analysis.