Inclusion Criteria

DISEASE CHARACTERISTICS:

- Histologically confirmed breast cancer

- Stage IIIB, IIIC, or IV disease

- Measurable or evaluable disease

- Measurable disease defined as masses with clearly defined margins AND at least 1
diameter ≥ 20 mm by radiography OR ≥ 10 mm by spiral CT scan

- Evaluable disease defined as masses without clearly defined margins on
radiological images OR no diameter ≥ 20 mm

- Patients with bone only disease eligible if disease is evaluable

- No brain metastases

- Hormone receptor status:

- Estrogen receptor- and/or progesterone receptor-positive

PATIENT CHARACTERISTICS:

Age

- Postmenopausal

Sex

- Female

Menopausal status

- Postmenopausal

Performance status

- ECOG 0-1

Life expectancy

- Not specified

Hematopoietic

- Neutrophil count ≥ 1,500/mm^3

- Platelet count ≥ 100,000/mm^3

- Hemoglobin ≥ 10.0 g/dL

Hepatic

- Bilirubin ≤ 1.5 times upper limit of normal (ULN)

- AST and ALT ≤ 2 times ULN

- Alkaline phosphatase ≤ 2.5 times ULN

Renal

- Creatinine ≤ 1.5 times ULN

Cardiovascular

- No significant QTcF prolongation (i.e., QTcF ≥ 470 msec)

Other

- No situation or condition that would preclude study participation

- No known or suspected hypersensitivity to any excipients of lonafarnib (e.g.,
povidone, poloxamer 188, croscarmellose sodium, silicon dioxide, or magnesium
stearate)

PRIOR CONCURRENT THERAPY:

Biologic therapy

- No prior or concurrent biologic therapy

- No prior or concurrent immunotherapy

Chemotherapy

- Prior adjuvant chemotherapy allowed provided the disease-free interval from
completion of treatment to diagnosis of advanced or metastatic disease is ≥ 12 months

- No prior chemotherapy for advanced disease

- No concurrent chemotherapy

Endocrine therapy

- Prior adjuvant tamoxifen allowed provided the disease-free interval from completion
of treatment to diagnosis of advanced or metastatic disease is ≥ 12 months

- No prior hormonal therapy for advanced disease

- No prior aromatase inhibitors

- More than 2 days since prior and no concurrent high-dose chronic steroids

- No concurrent hormone replacement therapy

- No other concurrent hormonal therapy

Radiotherapy

- Prior radiotherapy allowed

- No concurrent radiotherapy except palliative radiotherapy for bone metastasis

Surgery

- Not specified

Other

- More than 30 days since prior investigational drugs

- No prior farnesyl transferase inhibitors

- More than 2 days since prior and no concurrent use of any of the following inducers
or inhibitors of CYP3A4:

- Ethinyl estradiol

- Gestodene

- Itraconazole

- Ketoconazole

- Cimetidine

- Erythromycin

- Carbamazepine

- Phenobarbital

- Phenytoin

- Rifampin

- Sulfinpyrazone

- No concurrent participation in another clinical trial

- No other concurrent investigational therapy