Effectiveness of chemo drug pemetrexed?

My mother is suffering with stage IV metastatic bladder cancer in her stomach. She just survived 5 months of chemo(carboplatin and gemcitabene) to deal with the metatastes to her lymph nodes, which by the way was very effective. Her DR. is now treating with pemetrexed once every three weeks. He said it usually takes 2 to 3 treatments before it works. Can anyone confirm this? Mom now has two obstructions and cancer seems to be growing quickly.