Difficulty treating mets in brain

My wife, diagnosed in Mar 2016, has gone through 2+ years of treatment. The cancer in the body was eliminated late 2017 but so far unsuccessful in eliminating the mets in the brain.

One Intrathecal treatment using DepoCyt (Liposomal Cytarabine) seem to have some effect hope but the FDA wrote them up for some issue with production and sterlization and they chose to stop making it.

She's then been on amethopterin (Methotrexate) but that did not work.

Moved on to Gemzar (Gemcitabine) and Paraplatin (Carboplatin), no effect.

Added Cytosine (Cytarabine), no effect.

Now on Intrathecal Herceptin (Trastuzumab) and IV Halaven (Erbulin) but does not seem to be working. Symptoms now include lost use of right leg (very weak and knee buckles but feeling returned) recent week right arm (very weak but have feeling) and this week starting to affect ability to speak (brain knows but affecting ability to speak).

...

Oncologist said what had worked on the body was THP (Docetaxel, Trastuzumab and Pertuzumab)... wondering if there are any new developments or clinical trials to allow Intrathecal administration of THP. I did see one clinical trial for Intrathecal HP but had only 1 participant and was terminated (ClinicalTrials.gov Identifier: NCT02598427)

Fearing this might be the last treatment before insurance will deny us further treatments. Other ideas?