Inclusion Criteria:

- Must meet 1 of the following criteria:

- Histologically or cytologically confirmed breast or other cancer, such as lung
cancer, melanoma, etc., with newly diagnosed metastatic disease to the brain
(phase I)

- Patients who have available systemic therapeutic options with a
demonstrated survival benefit will not be eligible

- Histologically or cytologically confirmed breast cancer with newly diagnosed
metastatic disease to the brain

- Estrogen receptor-negative disease (phase II)

- Patients with newly diagnosed brain metastases who have received therapeutic regimens
with well-characterized, delayed toxicity (e.g., hematologic toxicity observed
following carmustine or mitomycin C) will not receive experimental therapy until the
patient has adequately recovered from all drug-related toxicities

- Measurable disease in the brain, defined as >= 1 lesion that can be accurately
measured in >= 2 dimensions (longest diameter and its longest perpendicular diameter
to be recorded)

- Tumor HER2/neu status positive or negative

- No leptomeningeal metastases

- Menopausal status not specified

- Karnofsky performance status (PS) 70-100%

- Recursive Partitioning Analysis (RPA) class I or II

- A small feasibility cohort of 10 RPA class III (Karnofsky PS < 70%) allowed,
however they will not be included in the efficacy analysis

- WBC >= 3,000/mm^3

- ANC >= 1,000/mm^3

- Platelet count >= 100,000/mm^3

- Hemoglobin >= 9 g/dL

- Total bilirubin normal

- AST (SGOT) =< 2.5 times upper limit of normal (ULN)

- ALT (SGPT) =< 2.5 times ULN

- Creatinine normal OR creatinine clearance >= 60 mL/min

- Fertile patients must use 2 forms of effective contraception (i.e., barrier
contraception and one other method of contraception) for the duration of study and
for >= 12 months after treatment

- Negative pregnancy test

- Not pregnant or nursing

- Able to swallow pills

- No history of allergic reactions attributed to compounds of similar chemical or
biologic composition to gamma-secretase inhibitor RO4929097

- No malabsorption syndrome or other condition that would interfere with intestinal
absorption

- Not known to be serologically positive for hepatitis A, B, or C, or have a history of
liver disease, other forms of hepatitis, or cirrhosis

- No uncontrolled electrolyte abnormalities including hypocalcemia, hypomagnesemia,
hyponatremia, hypophosphatemia, or hypokalemia despite adequate electrolyte
supplementation

- No uncontrolled electrolyte abnormalities including hypocalcemia, hypomagnesemia, and
hypokalemia

- No uncontrolled intercurrent illness including, but not limited to, any of the
following:

- Ongoing or active infection

- Symptomatic congestive heart failure (NYHA class III or IV)

- Unstable angina pectoris

- A history of torsades de pointes or other significant cardiac arrhythmias

- Stable atrial fibrillation

- Psychiatric illness and/or social situations that would limit compliance with
study requirements

- Baseline QTcF > 450 msec (male) or QTcF > 470 msec (female)

- No requirement for antiarrhythmics or other medications known to prolong QTc

- The use of oral or intravenous corticosteroids is allowed as needed for symptomatic
management of cerebral edema

- Typical doses of dexamethasone include 4 mg, up to four times daily,
administered either orally or intravenously

- Any type or number of prior therapies allowed

- No prior therapy with Notch inhibitors

- No prior cranial radiation

- Therapy-naive patients allowed

- At least 14 days since any prior experimental therapy, chemotherapy, or radiotherapy
and recovered to < grade 2 toxicities

- No other concurrent investigational agents

- No concurrent combination antiretroviral therapy in HIV-positive patients

- No concurrent medications with narrow therapeutic indices that are metabolized by
cytochrome P450 (CYP450), including warfarin sodium (Coumadin®)

- No concurrent medications that are generally accepted by the QTdrugs.org Advisory
Board to carry a risk for Torsades de Pointes, including antiemetics

- No concurrent medications that are strong inducers/inhibitors or substrates of CYP3A4

- No concurrent medications or food that may interfere with the metabolism of
gamma-secretase inhibitor RO4929097, including ketoconazole and grapefruit juice

- No other concurrent anticancer agents or therapies