I think Teva is bearing the cost of enrolling those additional 250 patients, since under the partnership agreement OGXI's contribution to all the P3 trials for OGX-011 is limited to $30mm. Of course, with two futility analyses and an interim efficacy analysis planned, there's a fair chance the trial will end early, and whether the ending is good or bad the trial cost would be reduced. So it's a clever strategy on Teva's part.
If the lung trial goes the distance OGXI is now saying it will continue beyond 2014 when their current cash will run out, assuming there are no new partnerships (e.g. for 427). So in a sense we the stockholders will bear the cost of the expansion of the trial size since if there's no early ending or new partnership OGXI will need to do another financing. They were probably going to do one before 2014 anyway though.
I don't understand their refusal to provide enrollment updates or project when trial results may be available. I think it just leads people to assume that things are progressing slowly.