Ion channel inhibitors enhance the eradication of tumor spheroid. Confocal images of infiltration of CEM-CAR cells into Raji (CD19⁺) tumor spheroid presence of 1 µM TRAM34 (A) and 10 nM Vm24 (B) (left). The images represent a middle slice of z-stack images. Histograms display the total (black), dead (Live-or-Dye 640/662 positive cells, red) and CEM-CAR (sGFP-CD19-CAR expressing, green) cell number in a slice vs. relative slice position (0 position: middle section, right). (C) The tumor elimination of CEM-CAR cells in the presence of TRAM34 (1 µM, KCa3.1 blocker) or Vm24 (10 nM, Kv1.3 inhibitor) depicted with IR, KR and KE after 24 h for 15 Raji (blue) and 4 Raji along with 10 nM Vm24 (red, Raji + 10 nM Vm24), and 5 Raji with 1 µM TRAM34 (purple, Raji + 1 µM TRAM34) spheroids. (D) Parameters of tumor elimination (IR, KR and KE) of CEM-CAR cells with TRAM34 in Vm24 in CD19 MCF-7 cells are calculated for 6 CD19 MCF-7 (blue), 4 CD19 MCF-7 with 10 nM Vm24 (red, CD19 MCF-7 + 10 nM Vm24), and 4 CD19 MCF-7 along with 1 µM TRAM34 (purple, CD19 MCF-7 + 1 µM TRAM34). (E) Parameters of tumor elimination (IR, KR and KE) of CAR-T cells with TRAM34 and Vm24 are displayed (incubation: 24 h) for 8 Raji (blue, Raji) and 5 Raji with 10 nM Vm24 (red, Raji + 10 nM Vm24), and 4 Raji with 1 µM TRAM34 (purple, Raji + 1 µM TRAM34) spheroids. Data are plotted as mean ± SEM; *P < 0.05; **P < 0.01; ***P < 0.001; ****P < 0.0001; n.s., not significant.