Chemical structures: Chemical structures of Pomalidomide ; Thalidomide and Lenalidomide are very similar:     Lenalidomide, initially known as CC-5013 and marketed as Revlimid by Celgene, is a derivative of thalidomide introduced in 2004. It was initially intended as a treatment for multiple myeloma, for which thalidomide is an accepted therapeutic modality, but has also shown efficacy in the class of hematological disorders known as myelodysplastic syndromes (MDS). Revlimid is also known as Revamid in the UK.The exact mechanism of the immunomodulatory drugs (i.e., thalidomide, CC-4047/Actimid and lenalidomide) is not known. Apart from interfering with the immune system, they are also thought to act on angiogenesis. Lenalidomide and bortezomib are considered therapeutic breakthroughs in myeloma, which generally carries a poor prognosis.   Lenalidomide is an off-white to pale-yellow solid powder. It is soluble in organic solvent/water mixtures, and buffered aqueous solvents. Lenalidomide is more soluble in organic solvents and low pH solutions. Solubility was significantly lower in less acidic buffers, ranging from about 0.4 to 0.5 mg/ml. Lenalidomide has an asymmetric carbon atom and can exist as the optically active forms S(-) and R(+), and is produced as a racemic mixture with a net optical rotation of zero.   REVLIMID® (lenalidomide) is available in 5 mg, 10 mg, 15 mg and 25 mg capsules for oral administration. Each capsule contains lenalidomide as the active ingredient and the following inactive ingredients: lactose anhydrous, microcrystalline cellulose, croscarmellose sodium, and magnesium stearate. The 5 mg and 25 mg capsule shell contains gelatin, titanium dioxide and black ink. The 10 mg capsule shell contains gelatin, FD&C blue #2, yellow iron oxide, titanium dioxide and black ink. The 15 mg capsule shell contains gelatin, FD&C blue #2, titanium dioxide and black ink.   The mechanism of action of lenalidomide remains to be fully characterized. Lenalidomide possesses antineoplastic, immunomodulatory and antiangiogenic properties. Lenalidomide inhibited the secretion of pro-inflammatory cytokines and increased the secretion of antiinflammatory cytokines from peripheral blood mononuclear cells. Lenalidomide inhibited cell proliferation with varying effectiveness (IC50s) in some but not all cell lines. Of cell lines tested, lenalidomide was effective in inhibiting growth of Namalwa cells (a human B cell lymphoma cell line with a deletion of one chromosome 5) but was much less effective in inhibiting growth of KG-1 cells (human myeloblastic cell line, also with a deletion of one chromosome 5) and other cell lines without chromosome 5 deletions. Lenalidomide inhibited the growth of multiple myeloma cells from patients, as well as MM.1S cells (a human multiple myeloma cell line), by inducing cell cycle arrest and apoptosis. Lenalidomide inhibited the expression of cyclooxygenase-2 (COX-2) but not COX-1 in vitro.