Figure 3. Survival study in the YUMM1.7 melanoma model in mice. Mice-bearing YUMM1.7 tumors were treated when the tumors were ~60 mm³. The dual-LNPs were injected intratumorally (IT) weekly for a total of 4 weeks at a dose containing 4 µg of CPG and 10 µg of VISTA siRNA. Mice were IT injected with VISTA-siRNA-only LNPs at a dose of a 10 µg siRNA 3 days after a dual-LNP treatment. Similar schedule/dose were used for the control treatments. (A) Tumor growth curves for groups treated with dual LNP (n=21 mice), control LNP (VISTA siRNA+non-stimulatory GPC; n=5 mice), control LNP (CPG+non-targeting siRNA; n=5 mice), vehicle LNP (n=5 mice), CPG and VISTA mAb (n=5 mice), or PBS (n=13 mice). (B) Kaplan-Meier survival. (C) Tumor growth curves of the complete responders and non-complete responders in the dual-LNP-treated group. (D) Kaplan-Meier survival of complete and non-complete responders in the dual-LNP-treated group. (E) A subset of complete responders (n=5) was rechallenged with YUMM1.7 cells on their opposite flank 30 days after completion of the dual-LNP treatments. The tumor growth was compared with naïve controls (n=7). (F) Kaplan-Meier survival of rechallenged mice. A subset of complete responders (n=5) was used for ELISPOT assays. CD4 and CD8 T cells were isolated 12 days following rechallenge. T cells were stimulated with irradiated YUMM1.7 cells (100 Gy). (G) ELISPOT results for Granzyme B from lymphatic CD8⁺ T cells following rechallenge. (H) ELISPOT results for IFN-γ from splenic CD8⁺ T cells following rechallenge. Statistics were analyzed by Student’s t-test. LNP, lipid nanoparticle; VISTA, V-domain immunoglobulin suppressor of T cell activation; PBS, phosphate-buffered saline.