Inclusion Criteria:

- At least 18 years of age

- Relapsed or Refractory Non Small Cell Lung Cancer (NSCLC) after at least one line of
therapy

- Eastern Cooperative Oncology Group (ECOG) performance status ≤ 2

- Histologically or cytologically confirmed Stage III B/IV NSCLC

- Adequate hematological, hepatic, and renal function

- Available during the first 8 weeks of the study treatment period to visit the clinic
for oral Mucositis assessments on scheduled days

Exclusion Criteria:

- Active concurrent malignancy. If there is a history of prior malignancies other than
those exceptions listed above, the patient must be disease-free for at least 5 years

- Congestive heart failure

- Uncontrolled hypertension

- Known human immunodeficiency virus (HIV)-positive diagnosis

- Previous exposure to Pralatrexate

- Pregnant or breast-feeding women

- Major surgery within 14 days of enrollment

- Active uncontrolled infection, underlying medical condition, or other serious illness
that would impair the ability of the patient to receive protocol treatment

- Symptomatic central nervous system (CNS) metastases or lesions for which treatment is
required. Patients who received prophylactic CNS treatment are eligible