Figure 4.

Combination of p-Tvax vaccine and OX40 agonists delays tumor growth and improves survival in subcutaneous and intraperitoneal mouse models of MM. (A) BALB/c mice were injected s.c. with 5 × 10⁴ CRH5 MM cells, or i.p. with 2 × 10⁵ EOH6 MM cells expressing luciferase. Seven and 14 d after tumor injection, mice were vaccinated with a s.c. injection of p-Tvax peptides. CpG adjuvant was injected at days 5 and 12, while 200 μg of OX86 was injected at day 9 and 14. Tumor volumes are showed on the left and animal survivals on the right for mice injected with CRH5 (Top) and EOH6 (Bottom). Tumor volumes were measured weekly with a caliper for s.c. tumors. I.p. MM dimensions were assessed by measuring luciferase activity with IVIS imaging following injection with luciferin substrate. Statistical significance between unvaccinated controls and single treatment (^*) as well as between single and combination treatments (^**), was determined by ANOVA followed by Bonferroni test (^*p < 0.05, n = 5). For survival, mice were followed until s.c. CRH5 tumors reached volumes of 300 mm³ and were then sacrificed. In i.p. models with EOH6 MM cells, survival was assessed by euthanizing mice at first sign of morbidity. Log-rank analysis was used to determine significance between control and single treatment (^*), and between single and combination treatments (^**) (p < 0.05, n = 5). (B) Representative images from IVIS tumor dimension analysis of mice carrying EOH6 tumors, vaccinated with the different immunotherapies.