Agatolimod and Trastuzumab in Treating Patients With Locally Advanced or Metastatic Breast Cancer

DISEASE CHARACTERISTICS:

Histologically or cytologically confirmed breast cancer

Locally advanced or metastatic disease
HER2-overexpressing tumor, defined as 3+ overexpression by IHC and/or HER2 amplified by FISH
Non-measurable disease allowed

Achieved partial response, complete response, or stable disease (i.e., no disease progression for ≥ 12 weeks) while on trastuzumab (Herceptin®) and chemotherapy, hormonal therapy alone, or trastuzumab alone

Last dose of trastuzumab must have been administered within the past 16 weeks

No unstable brain metastases

Patients with brain metastases are eligible provided they have been stable for ≥ 1 month after surgery or radiotherapy/radiosurgery AND off corticosteroids and anticonvulsants for ≥ 4 weeks
Hormone receptor status unspecified

PATIENT CHARACTERISTICS:

ECOG(Eastern Cooperative Oncology Group)performance status (PS) 0-2 (Karnofsky PS 70-100%)
Absolute neutrophil count ≥ 1,500/mm³
Hemoglobin > 8 g/dL (transfusion/epoetin alfa allowed)
Platelet count ≥ 100,000/mm³
Total bilirubin < 1.5 times upper limit of normal (ULN)
AST and ALT ≤ 2.5 times ULN (≤ 5.0 times ULN if known liver metastases)
Creatinine < 2 mg/mL
Ejection fraction ≥ 50% by echocardiogram or MUGA
Not pregnant or nursing
Negative pregnancy test
Fertile patients must use effective contraception before, during, and for ≥ 3 months after completion of study treatment
No ongoing or active infection requiring oral or IV antibiotics
No known autoimmune disorders or antibody-mediated disorders
No known HIV positivity
No known history of hepatitis B or C (active and/or previously treated)
No other malignancies within the past 5 years except nonmelanoma skin cancer or cervical cancer in situ
No history of allergic reactions attributed to compounds of similar chemical or biologic composition to study drugs

PRIOR CONCURRENT THERAPY:

See Disease Characteristics
More than 12 weeks since prior chloroquine
More than 4 weeks since prior growth factors
More than 4 weeks since prior systemic corticosteroids
More than 4 weeks since prior chemotherapy, radiotherapy, or monoclonal antibody therapy (except trastuzumab)
No prior agatolimod sodium
No prior allogeneic stem cell transplantation
No prior continuous treatment with single-agent trastuzumab for > 6 months
No more than 3 prior chemotherapy regimens for metastatic breast cancer
Any number of prior hormonal therapies allowed
No other concurrent investigational agents or monoclonal antibodies
No other concurrent anticancer agents or therapies
Concurrent bisphosphonates for skeletal metastasis allowed