Enhanced Antitumor Effect of the Combination of Bacille Calmette-Gurin and an Immune Checkpoint Inhibitor in Bladder Cancer-On-a-Chip

We upgraded preexisting bladder cancer-on-a-chip (BCOC) by adding T cells and evaluated the antitumor effect of a combination of intravesical Bacille Calmette-Guerin (BCG) and pembrolizumab. We fabricated bioprinted BCOC with microfluids, incorporating HT1376, MRC-5, HUVEC, THP-1 and Jurkat cells. We evaluated the effector-to-target cytotoxicity, cytokine, and cell viability in 2D culture, live/dead assay, migration assay, and cytokine assay in BCOC. Additionally, we evaluated the antitumor efficacy of the combination of BCG and pembrolizumab in an orthotopic mouse model. The combination group showed the most effective reduction compared to the control in 2D culture (100.0 +/- 0.8% vs. 36.4 +/- 0.8%, p < 0.001). In BCOC, cancer cell viabilities were decreased at 3 days in the BCG group (70.1 +/- 9.8%, p = 0.013) and combination group (49.3 +/- 8.1%, p < 0.001). The combination group showed the highest immune reaction in the cytokine assay (interferon-gamma, p = 0.045; interleukin-6, p = 0.037) and migration assay (fold change 1.3 +/- 0.1, p < 0.001), whereas in the in vivo model, it showed lower signal intensities from days 10 to 14 compared to that in the control group (p = 0.031 and p = 0.014, respectively). No significant weight changes were observed among the groups. We developed a 3D bioprinted BCOC via use of the monocytic THP-1 cells and Jurkat T cells to assess the efficacy of immunotherapy. The combination of BCG and pembrolizumab showed the best antitumor efficacy in BCOC and animal models.