ARQ 621 is an investigational small molecule inhibitor targeting the eukaryotic initiation factor 4A (eIF4A), a key component of the translation initiation complex. It is primarily studied for its potential in oncology, particularly in hematologic malignancies. The compound has shown preclinical activity against certain leukemias and lymphomas by selectively inhibiting the translation of oncogenic proteins that are highly dependent on eIF4A for their expression. This includes proteins involved in cell proliferation and survival, such as MYC and BCL-2 family members. ARQ 621 has been evaluated in early-phase clinical trials to assess its safety and efficacy, especially in patients with relapsed or refractory acute myeloid leukemia (AML) and other advanced blood cancers. Its mechanism allows for targeted disruption of cancer cell protein synthesis while sparing normal cells to some extent, offering a potential therapeutic window. Research is ongoing to determine optimal dosing, combination strategies, and patient selection criteria.