BETHESDA, Md—Thalidomide (Thalomid) appears to inhibit angiogenesis (the recruitment of new blood vessels by the tumor). Clinically, thalidomide has been shown to lower PSA levels in some patients with androgen-independent prostate cancer. Using an LNCaP in vitro model, thalidomide has been shown to slightly increase the amount of PSA per cell number. "Some drugs appear to upregulate the expression of PSA and some downregulate it," William Dahut, MD, of the National Cancer Institute, said at an NCI conference on urologic oncology. This is clearly the case for carboxyamidotriazole (CAI) and TNP-470, both angiogenesis inhibitors, he said. CAI has been shown to downregulate PSA, whereas TNP-740 upregulated it.