This study will investigate the effect of oral LBH589 on dextromethorphan, a CYP2D6 substrate, and to assess safety and efficacy of oral LBH589 when used with this co-medication in advanced stage NSCLC or malignant pleural mesothelioma patients

Inclusion criteria:

1. Age ≥ 18 years
2. Must have histologically or cytologically confirmed advanced or metastatic incurable solid tumor as documented by CT or MRI that has progressed on or following standard therapies
3. Must have failed prior standard systemic therapy
4. Must have at least one measurable and/or non-measurable lesion as defined by RECIST criteria
5. Baseline MUGA or ECHO must demonstrate LVEF ≥ the lower limit of the institutional normal.
6. Written informed consent obtained prior to any screening procedures
7. Willingness to have multiple blood draws
8. Ability to swallow capsules or tablets

Exclusion criteria:

1. Uncontrolled brain metastases
2. Prior treatment with an HDAC inhibitor
3. Presence of clinically detectable third-space fluid collections (e.g., ascites or pleural effusions) that can not be controlled by drainage or other procedures prior to study entry
4. Concomitant use of any anti-cancer therapy, including radiation therapy
5. Significant cardiac disease
6. Concomitant use of drugs with a risk of causing torsades de pointes
7. Impairment of gastrointestinal (GI) function or GI disease that may significantly alter the absorption of oral LBH589
8. Previous use of monoamine oxidase inhibitors (e.g. clorgyline, iproniazid, isocarboxazid, moclobemide, sibutramine, phenelzine, tranylcypromine) within 14 days prior to the first dose of dextromethorphan