Lenalidomide hydrochloride (CC-5013 hydrochloride), a Thalidomide derivative, functions as molecular glue and serves as an orally active immunomodulator. As a ligand for the ubiquitin E3 ligase cereblon (CRBN), it facilitates the selective ubiquitination and degradation of the lymphoid transcription factors IKZF1 and IKZF3 through the CRBN-CRL4 ubiquitin ligase. Specifically, Lenalidomide hydrochloride inhibits the growth of mature B-cell lymphomas, including multiple myeloma, and promotes IL-2 release from T cells [1] [2].

Lenalidomide is potent in stimulating T cell proliferation and IFN-γ and IL-2 production. Lenalidomide has been proven to inhibit production of pro inflammatory cytokines TNF-α, IL-1, IL-6, IL-12 and elevate the production of anti-inflammatory cytokine IL-10 from human PBMCs. Lenalidomide downregulates the production of IL-6 directly and also by inhibiting multiple myeloma (MM) cells and bone marrow stromal cells (BMSC) interaction, which augments the apoptosis of myeloma cells [2]. Dose-dependent interaction with the CRBN-DDB1 complex is observed with Thalidomide, Lenalidomide and Pomalidomide, with IC 50 values of ~30 μM, ~3 μM and ~3 μM, respectively, These reduced CRBN expression cells (U266-CRBN 60 and U266-CRBN 75 ) are less responsive than the parental cells to antiproliferative effects Lenalidomide across a dose-response range of 0.01 to 10 μM [3]. Lenalidomide, a thalidomide analog, functions as a molecular glue between the human E3 ubiquitin ligase cereblon and CKIα is shown to induce the ubiquitination and degradation of this kinase, thus presumably killing leukemic cells by p53 activation [5].

The toxicity of Lenalidomide doses up to 15, 22.5, and 45 mg/kg via IV, IP, and PO routes of administration. Limited by solubility in our PBS dosing vehicle, these maximum achievable Lenalidomide doses are well tolerated with the exception of one mouse death (of four total dosed) at the 15 mg/kg IV dose. Notably, no additional toxicities are observed in the study at IV doses of 15 mg/kg (n=3) or 10 mg/kg (n=45) or at any other dose level through IV, IP, and PO routes [4].