Fig. 3
Mn2+ plus YM101 therapy had a potent and durable antitumor activity in vivo. All mice were treated every other day for 12 days. For Mn2+ administration, mice received 5 mg/kg Mn2+ intranasally or intratumorally. For Ab treatment, mice were treated with equivalent mole hIgG (6.6 mg/kg), α-PD-L1 (6.6 mg/kg), or YM101 (9 mg/kg) by intraperitoneal injection. a–c BALB/c mice were subcutaneously inoculated in the right groin with 1 × 106 CT26 cells on day 0. Tumor-bearing mice were randomized into six groups: Isotype control, Mn2+, α-PD-L1, Mn2+ plus α-PD-L1, YM101, and Mn2+ plus YM101 (eight mice for each group). Treatment started on day 4. The representative images of CT26 tumors, tumor growth curves, and tumor weights are shown. d–f BALB/c mice were inoculated in the right mammary fat pad with 5 × 105 EMT-6 cells on day 0. Tumor-bearing mice were randomized into six groups: Isotype control, Mn2+, α-PD-L1, Mn2+ plus α-PD-L1, YM101, and Mn2+ plus YM101 (eight mice for each group). Treatment was initiated on day 4. The representative images of EMT-6 tumors, tumor growth curves, and tumor weights are shown. g–i BALB/c mice were subcutaneously inoculated in the right groin with 2 × 106 H22 cells on day 0. Tumor-bearing mice were randomized into four groups: Isotype control, Mn2+, YM101, and Mn2+ plus YM101 (eight mice for each group). Treatment started on day 4. The representative images of H22 tumors, tumor growth curves, and tumor weights are shown. j–l C57BL/6 mice were subcutaneously inoculated with 2 × 105 B16 cells on day 0. Treatment was started on day 1 (eight mice for each group). The representative images of B16 tumors, tumor growth curves, and tumor weights are shown. (m) The schematic diagram of the rechallenge assay. BALB/c mice were inoculated with 3 × 105 EMT-6 cells in the right mammary fat pad. Therapy was initiated on day 1. Mice received six times of treatments in 12 days. One week after the last treatment, the cured or treatment-naïve mice were rechallenged with 3 × 105 EMT-6 cells. (n–o) The representative images of EMT-6 tumors and tumor growth curves in the rechallenge assay are shown. *p < 0.05, **p < 0.01, ***p < 0.001, and ****p < 0.0001 denote the significant difference relative to Mn2+ plus YM101 therapy when not marked with lines. CR: complete regression