PBNP-PTT + aCD137 generates an increase in serum cytokines/chemokines associated with T cell activation. Synchronous SM1 tumors were established and treated as previously described. On Day 14, blood was harvested and serum was analyzed for (a) TNFα, (b) IL-5, (c) IL-10, (d) Fas ligand, (e) MIP-1a, and (f) RANTES expression. Normalized values in the negative range are listed as “0” pg/mL. Values represent mean ± SD, n = 5/group; ns: not significant, *p < 0.05, **p < 0.01, ***p < 0.001, ****p < 0.0001.