To study the efficacy of Alimta as a single agent in thymic cancers

The broad range of clinical activity of thymic carcinomas makes the likelihood of detecting efficacy of a single agent such as premetrexed a reasonable objective since these malignancies are relatively slow growing and exhibit a broad range of chemosensitivity to antineoplastic agents.

Inclusion Criteria:

• Histologically confirmed invasive, recurrent or metastatic thymoma or thymic carcinoma not amenable to potentially curative therapy by surgery. Original biopsy of tumor is sufficient for diagnoses unless otherwise clinically indicated.
• Patients must have measurable disease with at least one bidimensional measurable lesion. Any scans or x-rays used to document measurable disease must be obtained with 6 weeks prior to registration.
• Patients may have had prior chemotherapy for metastatic disease
• Adequate organ function as defined by: bili </=1.5; calc. crt clr of >/=45; hematologic-granulocytes >/=1500 & plt >/=100K.
• Patients who are receiving a stable dose of corticosteroids for myasthenia gravis are eligible.
• ECOG performance status of 0 or 1

Exclusion Criteria:

• Acute intercurrent infection or complications
• pregnancy or lactating patients
• Inability to interrupt aspirin or other nonsteroidal anti-inflammatory agents for a 5-day period (8-day period for long-acting agents.
• Presence of clinically relevant third-space fluid collections that cannot be controlled by a procedure

Beginning of treatment until the end of the study, up to 3 years