Do you hold or avoid pemetrexed in patients with NSCLC and pleural effusions?

I do not. Given pemetrexed's relationship to methotrexate as an antifolate, the question has come up of whether the same precautions taken with methotrexate regarding effusions/third space fluid are necessary for pemetrexed. Thankfully, this does not appear to be the case, as several studies (here is one which included pleural effusions and ascites, and another much smaller one) have evaluated this and found no evidence to support draining pleural effusions prior to pemetrexed.