6ThiodG induces anti-tumor immunity in SCLC

There are few effective treatments for small cell lung cancer (SCLC). We explored a major dependency of small cell lung cancer as a therapeutic target. Nearly all of SCLCs have telomerase activity and they are dependent on this enzyme for their ability to continuously divide. We utilized a nucleoside analog, 6-Thio-2’-deoxyguanosine (6TdG), that is preferentially recognized by telomerase to promote telomere dysfunction. Low and intermittent doses of 6TdG inhibited tumor growth and metastasis from the primary tumors. Anti-tumor activity of 6TdG was associated with decrease in cancer initiation cell (CIC) markers L1CAM/CD133 and increase in visibility to innate and adaptive immunity. Mechanistically, 6TdG depleted CICs and induced type-I interferon signaling by activating tumor STING. We confirmed the functional essential role of CIC markers L1CAM/CD133 in SCLC tumor initiation. We also observed dramatic synergy between 6TdG and irradiation in both syngeneic and humanized SCLC models that was dependent on immune cells. scRNA-seq of SCLC-bearing mouse livers, control and 6ThiodG-treated. Contacts for data availability: [e-mail] [e-mail] [e-mail]