Michka, here's a link to all T-DM1 trials, contact information and their current status.
http://www.clinicaltrials.gov/ct2/results?term=t-dm1
Although "weekly" dosing has been looked at, Genentech currently doses on a three week schedule. As long as drug remains efficacious, even after completing trial, Genentech will continue to provide for drug.
Don't rule out any of the trials because passed experience with trastuzumab because T-DM1 has functioned in patients that were non-sensitive to Herceptin.
Contacting Genentech directly might give you best idea as to how to proceed.