Inclusion Criteria

DISEASE CHARACTERISTICS:

- Histologically or cytologically confirmed metastatic adenocarcinoma of the breast

- HER2/neu 3+ by immunohistochemical staining

- 2+ eligible provided HER2/neu positive by fluorescent in-situ hybridization
(FISH)

- HER2/neu positive by FISH alone allowed

- Unidimensionally measurable disease

- At least 20 mm by conventional techniques OR at least 10 mm by spiral CT scan

- Must have received prior trastuzumab (Herceptin)

- Patients with known brain metastases meeting any of the following criteria are not
eligible:

- Require high-dose steroid therapy or enzyme-inducing anticonvulsant drugs

- No prior cranial radiotherapy

- Have progressive neurologic dysfunction that would preclude study evaluation

- Have evidence of progressive CNS disease by CT scan or MRI

- Hormone receptor status:

- Not specified

PATIENT CHARACTERISTICS:

Age

- Over 18

Sex

- Male or female

Menopausal status

- Not specified

Performance status

- ECOG 0-2 OR

- Karnofsky 70-100%

Life expectancy

- At least 12 weeks

Hematopoietic

- Absolute neutrophil count at least 1,500/mm^3

- Platelet count at least 100,000/mm^3

- Hemoglobin at least 9.0 g/dL

Hepatic

- Bilirubin no greater than 1.5 times upper limit of normal (ULN)

- AST and ALT no greater than 2.5 times ULN (5 times ULN if liver metastases present)

Renal

- Creatinine no greater than 1.5 times ULN OR

- Creatinine clearance greater than 60 mL/min

Cardiovascular

- No symptomatic congestive heart failure

- No unstable angina pectoris

- No cardiac arrhythmia

- Ejection fraction greater than 50% by MUGA or echocardiogram

Gastrointestinal

- No gastrointestinal tract disease resulting in an inability to tolerate oral
medication

- No requirement for IV alimentation

- No active peptic ulcer disease

Other

- Not pregnant or nursing

- Negative pregnancy test

- Fertile patients must use effective contraception

- No significant traumatic injury within the past 21 days

- No other malignancy within the past 3 years except nonmelanoma skin cancer or
carcinoma in situ of the cervix

- No ongoing or active infection

- No prior allergic reaction attributed to compounds of similar chemical or biological
composition to tipifarnib (e.g., quinolones) or trastuzumab

- No psychiatric illness or social situation that would preclude study compliance

- No other concurrent medical illness that would preclude study compliance

PRIOR CONCURRENT THERAPY:

Biologic therapy

- See Disease Characteristics

- No prior bone marrow transplantation with high-dose chemotherapy

- No concurrent immunotherapy

Chemotherapy

- See Biologic therapy

- No more than 2 prior chemotherapy regimens for metastatic disease

- More than 4 weeks since prior chemotherapy (6 weeks for nitrosoureas or mitomycin)
and recovered

- Prior combination chemotherapy allowed

- No concurrent chemotherapy

Endocrine therapy

- See Disease Characteristics

- Prior hormonal therapy allowed

- No concurrent hormonal therapy for cancer

Radiotherapy

- See Disease Characteristics

- More than 4 weeks since prior wide-field radiotherapy and recovered

- No concurrent radiotherapy

Surgery

- Prior modified radical mastectomy or lumpectomy with axillary node dissection allowed

- Prior resection of metastatic lesions allowed

- More than 21 days since prior major surgery

- No prior surgery affecting absorption

Other

- No prior tipifarnib

- More than 6 weeks since initiation of bisphosphonate therapy (if bone lesions are the
only site of measurable disease)

- Bisphosphonate therapy may not be initiated during study

- No other concurrent investigational agents

- No other concurrent anticancer therapy

- No concurrent antacids within 2 hours of study drug