Molecular glue mediated degradation of cannabinoid receptor 1 for cancer therapy.

Kashkush A.; Tadesse K.; Insler B.; Benhamou R. · npj drug discovery · 2026

**Background & Methods** This review describes the development of covalent molecular glue degraders targeting cannabinoid receptor type 1 (CB1R) for cancer therapy. Researchers synthesized small molecules incorporating electrophilic E3 ligase-recruiting handles based on rimonabant as a CB1R-binding scaffold, with MG-CB2 identified as the lead compound. The degrader was evaluated in MCF-7 breast cancer and HepG2 hepatocellular carcinoma cell lines using biochemical assays, proteasome inhibition studies, and RNF126 knockdown experiments to establish mechanism of action. **Key Findings** - MG-CB2 induced concentration- and time-dependent depletion of CB1R in both cancer cell lines through a proteasome- and RNF126-dependent mechanism, as confirmed by proteasome inhibition blocking CB1R loss and RNF126 knockdown abolishing degradation. - CB1R degradation by MG-CB2 resulted in modulation of downstream signaling pathways, including reduced phosphorylation of ERK and mTOR, decreased BCL2 expression, and reduced cancer cell viability and migration capacity. - Cellular engagement of CB1R by MG-CB2 was validated through rimonabant competition assays and cellular thermal shift experiments, demonstrating specific molecular targeting. **Dosage & Administration** Not reported. This is a preclinical study with in vitro evaluation; specific dosing regimens and administration routes were not characterized. **Safety & Adverse Effects** Not reported. The study focused on mechanistic characterization and efficacy endpoints in cancer cell lines without formal safety or toxicity assessments in cellular or animal models. **Evidence Quality** This review presents preclinical research with significant limitations. Findings are restricted to in vitro cell culture models (MCF-7 and HepG2 lines) without in vivo validation in animal models or clinical trials. The study establishes proof-of-concept for molecular glue-mediated degradation of a transmembrane GPCR but does not provide comprehensive pharmacokinetic data, selectivity profiling against off-target proteins, or assessment of potential adverse effects. The mechanism-of-action studies provide good supporting evidence for proteasome-dependent degradation via RNF126 E3 ligase, but generalizability to other cancer types and patient populations remains unclear. Translation to clinical application would require extensive additional preclinical development, including animal efficacy and toxicology studies, before human trials could be considered.

More recent cannabis research