The immunomodulatory drug thalidomide has been shown to be clinically useful in a number of situations due to its ability to inhibit TNF-alpha synthesis. However, its use is restricted by potentially serious side effects, including teratogenicity and neuorotoxicity; furthermore, insolubility may present problems in terms of systemic bioavailability. Recently, structural modifications of thalidomide have been designed enabling greatly enhanced anti-TNF-alpha activity in LPS-treated mice. In contrast to thalidomide (LPS-induced TNF-alpha IC50 approximately 200 microM in DMSO) and other analogs tested, one of these compounds, CC-3052 (IC50 approximately 1 microM in water), is water soluble. Furthermore, this analog exhibits increased stability in human plasma (t(1/2) approximately 17.5 vs 1.5 h for thalidomide) and appears to be nontoxic, nonmutagenic, and nonteratogenic. At pharmacologically active levels, cellular proliferation and LPS-induced IL-6 mRNA and IL-12p40 mRNA (as well as IL-1beta and IL-6 protein levels) in whole blood cultures were not affected; apparent inhibition of NK activity by CC-3052 was reversed upon addition of exogenous rTNF-alpha. In addition, IL-10 mRNA and protein levels were increased. These properties are consistent with results indicating inhibition of phosphodiesterase type IV activity by CC-3052. Furthermore, CC-3052 did not increase the degradation rate of macrophage TNF-alpha transcripts nor inhibit LPS-induced primary macrophage NF-kappaB activation. Taken together, the potency of selective TNF-alpha inhibition, water solubility, and increased plasma stability make CC-3052 an excellent candidate for further development and clinical evaluation for the treatment of TNF-alpha-mediated disease.