Bear this pretty much explains it:

xB3-001: Bioasis' name for its xB3-TZM fusion protein, which is a molecule of TZM with one or more xB3 peptide structures fused to it for BBB transportation purposes. ( compliments of jdstox; Stockhouse )

TZM: trastuzumab being the name for Roche/Genentech's Herceptin.

Trastuzumab, sold under the brand name Herceptin among others, is a monoclonal antibody used to treat breast cancer. Specifically, it is used for breast cancer that is HER2 receptor positive. It may be used by itself or together with other chemotherapy medication.

HER2 (human epidermal growth factor receptor 2) is a gene that can play a role in the development of breast cancer.

xB3-001 attached to Trastuzumab helps it (TZM) to cross the BBB to attack HER2- expressing breast cancer that has spread to the brain. 

Koo