Inclusion Criteria

Inclusion Criteria (phase lb):

- Females with Breast cancer that is histologically or cytologically confirmed, HER2
negative and locally advanced or metastatic as confirmed by radiology

- ECOG performance status 0 and 1

- Adequate bone marrow and organ function

Exclusion Criteria (Phase lb):

- Previous treatment with PI3K and/or mTOR inhibitors

- Symptomatic Central Nervous System (CNS) metastases

- Concurrent malignancy or malignancy in the last 5 years prior to start of study
treatment

- Wide field radiotherapy ≤ 28 days or limited field radiation for palliation ≤ 14 days
prior to starting study drug

- Active cardiac disease (e.g. LVEF less than institutional lower limit of normal, QTcF
> 480 msec, unstable angina pectoris, ventricular, supraventricular or nodal
arrhythmias)

- Inadequately controlled hypertension

- Impairment of gastrointestinal (GI) function or GI disease that may significantly
alter the absorption of BEZ235 and/or paclitaxel

- Treatment at start of study treatment with drugs with a known risk to induce Torsades
de Pointes, moderate and strong inhibitors or inducers of isoenzyme CYP3A4, warfarin
and coumadin analogues, LHRH agonists

- Sensitivity to paclitaxel treatment

- Uncontrolled diabetes mellitus

- Pregnant or nursing (lactating) woman

Other protocol-defined inclusion/exclusion criteria may apply