TAS-102 has a tumoricidal activity in multiple myeloma

TAS-102/Lonsurf is a new oral anti-tumor drug consisting of trifluridine and tipiracil in a 1:0.5 molar ratio. Lonsurf has been approved globally, including US, Europe Union, and China, to treat patients with advanced colorectal cancer. Ongoing clinical trials are currently conducted for the treatment of other solid cancers. However, the therapeutic potential of TAS-102 in hematological malignancies has not been explored. In this study, we investigate the therapeutic efficacy of TAS-102 in multiple myeloma both in vitro and in vivo. We demonstrate that TAS-102 treatment inhibits tumor cell proliferation in six human myeloma cell lines with IC₅₀ values in a range from 0.64 to 9.10 μM. Dot blotting and immunofluorescent staining show that trifluridine is predominately incorporated into genomic DNAs of myeloma cells. TAS-102 treatment induces myeloma cell apoptosis through cell cycle arrest in G1 phase and activation of cGAS-STING signaling in myeloma cells. In the human myeloma xenograft models, TAS-102 treatment reduces tumor progression and prolongs mouse survival. TAS-102 has shown its efficacies in the drug-resistant myeloma cells, and the combination of TAS-102 and bortezomib has a synergistic anti-myeloma activity. Our preclinical studies indicate that TAS-102 is a potential novel agent for myeloma therapy.