Inclusion Criteria:

• Histologically or cytologically documented diagnosis of NSCLC that is advanced/metastatic (Stage IIIB/IV).
• Written informed consent.
• The presence of progressive and measurable disease as defined by the -Response Evaluation Criteria in Solid Tumors (RECIST)
• Performance status of 0 to 1 on the Eastern Cooperative Oncology Group (ECOG) Scale
• Have discontinued all previous systemic therapies for cancer, for at least 14 days prior to study entry and have had previous first line chemotherapy, have recovered from all acute effects of the therapies, and are considered for further chemotherapy, radiotherapy, or other investigational therapy after they have relapsed or progressed on previous treatment.
• Exhibit patient compliance and geographic proximity that allow for adequate follow-up.

• Adequate bone marrow reserve and organ function as follows:

  • Neutrophil count >1.5 x 10 to the 9th power/L and platelets > 100 x 10 to the 9th power/L.
  • Hepatic: total bilirubin less than or equal to 1.5 times upper limit of normal (ULN)
  • Alanine transaminase (ALT) and aspartate transaminase (AST) less than or equal to 2.5 times ULN (or less than or equal to 5 times ULN in case of known liver involvement
  • Renal: Serum Creatinine less than or equal to 1.5 times upper limit of normal (ULN)
• Reproductive potential must be either terminated (by surgery, radiation, or menopause) or attenuated by the use of an approved contraceptive method during and for 3 to 6 months following the study.
• At least 18 years of age.
• Agrees to discontinue St. Johns Wort while receiving dasatinib therapy
• Agrees that IV bisphosphonates will be withheld for the first 8 weeks of dasatinib therapy due to risk of hypocalcemia.

Exclusion Criteria:

• Prior treatment with EGFR tyrosine kinase inhibitors or EGFR targeting agent
• Have received treatment within the last 28 days with a drug that has not received regulatory approval for any indication at the time of study entry.
• Have previously completed or withdrawn from this study or any other study investigating Dasatinib.
• Pregnant or breastfeeding.
• Documented central nervous system or leptomeningeal metastasis (brain metastasis) at the time of study entry. Patients with prior brain metastasis may be considered if they have completed their treatment for brain metastasis, no longer require corticosteroids, and are asymptomatic.
• Serious concomitant disorder, including active bacterial, fungal, or viral infection, incompatible with the study (at the discretion of the investigator).
• Uncorrected electrolyte disorder, including potassium <3.0 mEq/L).
• Gastrointestinal disorder that in the opinion of the study physician may affect absorption of either erlotinib or dasatinib. This also includes the inability to swallow tablets.
• Prior major surgery or radiation therapy within 14 days of initiation of treatment
• Electrocardiogram (ECG) abnormalities indicative of cardiac disease (at the discretion of the investigator).
• Uncontrolled angina, congestive heart failure or MI within six (6) months
• Diagnosed or suspected congenital long QT syndrome
• History of clinically significant ventricular arrhythmias (such as ventricular tachycardia, ventricular fibrillation, or Torsades de pointes)
• Prolonged QTc interval on pre-entry electrocardiogram (> 450 msec)
• Uncontrolled hypertension.

• History of significant bleeding disorder unrelated to cancer, including:

  • Diagnosed congenital bleeding disorders (e.g., von Willebrand's disease)
  • Diagnosed acquired bleeding disorder within one year (e.g., acquired anti-factor VIII antibodies)

• Patients currently taking drugs that are generally accepted to have a risk of causing Torsades de Pointes including:

  • quinidine,
  • procainamide,
  • disopyramide,
  • amiodarone,
  • sotalol,
  • ibutilide,
  • dofetilide erythromycins,
  • clarithromycin,
  • chlorpromazine,
  • haloperidol,
  • mesoridazine,
  • thioridazine,
  • pimozide,
  • cisapride,
  • bepridil,
  • droperidol,
  • methadone,
  • arsenic,
  • chloroquine,
  • domperidone,
  • halofantrine,
  • levomethadyl,
  • pentamidine,
  • sparfloxacin; and
  • lidoflazine.
• Patients with chronic obstructive pulmonary disease or pleural effusions (malignant or benign) requiring chronic oxygen therapy.