CARM1-IN-5 (Compound 17e) is a potent and selective inhibitor of CARM1, exhibiting an IC50 of 2 nM. By directly interacting with CARM1, CARM1-IN-5 effectively inhibits the methylation of substrate proteins. Additionally, CARM1-IN-5 demonstrates significant antiproliferative effects on melanoma cell lines.

CARM1-IN-5 is selective for CARM1, showing an IC₅₀ of 2 ± 1 nM for CARM1, compared to 213 ± 45 nM for PRMT1, 942 ± 78 nM for PRMT3, 64 ± 9 nM for PRMT6, 73 ± 8 nM for PRMT8, and over 100,000 nM for PRMT5 and PRMT7. It exhibits antiproliferative activity against two melanoma cell lines with IC₅₀ values of 0.55 ± 0.03 μM for A375 and 1.74 ± 0.07 μM for A2058. CARM1-IN-5 (0-5 μM; 72 h) can penetrate A375 cells and bind directly to CARM1, affecting the asymmetrical dimethylation levels of CARM1 substrates in cellular environments by inhibiting the methyltransferase activity of CARM1. Its in vitro metabolic stability is indicated by a half-life (t₁/₂) of 41.5 minutes and a clearance rate (Cl) of 132 mL/min/kg.