Study of ACTR T Cell Product in Combination With Trastuzumab in Subjects With HER2-Positive Advanced Solid Tumor Cancers

Inclusion Criteria:

* Signed written informed consent obtained prior to study procedures
* Histologically-confirmed Her2 positive advanced solid tumor malignancy with documented disease progression during or immediately following the immediate prior therapy, or within 6 months of completing adjuvant therapy for subjects with breast cancer
* Subjects must have previously received adequate standard therapy for treatment of their malignancy

  * For those with metastatic breast cancer, must have received HER2-directed therapy including trastuzumab, pertuzumab and ado-trastuzumab in any breast cancer disease setting
  * For those with advanced gastric cancer, adequate prior treatment with HER2-directed chemotherapy is required
* At least 1 measurable lesion by iRECIST
* Able to provide fresh tumor biopsy or archived block specimen taken since time of most recent anti-HER2 mAb-directed therapy
* ECOG of 0 or 1
* Life expectancy ≥ 6 months
* LVEF ≥ 50% by MUGA or ECHO
* Absolute neutrophil (ANC) count ≥ 1500/ µL
* Platelet count ≥ 100,000/µL
* Hemoglobin ≥ 9g/dL
* Estimated GFR \>30mL/min/1.73m2

Exclusion Criteria:

* glioblastoma multiforme or other primary CNS tumors are excluded
* clinically significant cardiac disease
* clinically significant active infection
* clinical history, prior diagnosis, or overt evidence of autoimmune disease
* current use of more than 5mg/day of prednisone (or an equivalent glucocorticoid)
* Prior treatment as follows:

  * prior cumulative doxorubicin dose greater than or equal to 300 mg/m\^2 or equivalent
  * chemotherapy within 2 weeks of enrollment
  * external beam radiation within 2 weeks of enrollment (28 days if CNS-directed therapy)
  * any monoclonal antibody (mAb) or other protein therapeutic containing Fc-domains within 4 weeks of enrollment
  * pertuzumab within 4 months of enrollment
  * Experimental agents within 3 half-lives or 28 days prior to enrollment, whichever is shorter
  * allogeneic hematopoietic stem cell transplant (HSCT)
  * prior infusion of a genetically modified therapy
* Pregnant or breastfeeding