Three (3) different dose levels of pemetrexed will be studied. The first group of 6 participants will be treated at Dose Level 1 (lowest of the 3 doses) and evaluated for 3 weeks. If 0 or 1 out of 6 participants experience severe side effects at Dose Level 1, the next group of 6 participants will be treated at Dose Level 2. At any given dose, if greater than 1 out of 6 participants experience severe side effects, then no further participants will receive that dose or a higher dose.