Fig. 3

Intratumoral CD4-specific PET signals, [⁸⁹Zr]Zr-DFO-CD4 SUV_mean, on day 2 increased in ICB responders. A-B) Mean of standard uptake value (SUV_mean) at day 0 (A) and 2 (B) in MMTV-HER2 model. Overall, CD4 + cells were increased in the retained/infiltrated population in ICB responders in MMTV-HER2 model. C) Representative images of [⁸⁹Zr]Zr-DFO-CD4 PET from day 0 to day 6 in the combinational treatment group in the MMTV-HER2 model. Yellow circles indicated tumors. The responders showed a slightly increased [⁸⁹Zr]Zr-DFO-CD4 signal on day 2. All the images are processed at the same setting and decay corrected to the imaging time. D) Day 2 intratumoral [⁸⁹Zr]Zr-DFO-CD4 SUV_mean of each treatment group in MMTV-HER2 model. There was a trend of increase in α-PD-1 treated responders in the MMTV-HER2 model. E-F) [⁸⁹Zr]Zr-DFO-CD4 SUV_mean at day 0 (E) and 2 (F) in the 4T1 model. On day 2, retained/infiltrated CD4 + cells increased in ICB treatment responders relative to non-responders. E) Representative images of [⁸⁹Zr]Zr-DFO-CD4 PET from day 0 to day 6 in the combinational treatment group in the 4T1 model. Yellow circles indicated tumors. The responder group showed a slightly increased [⁸⁹Zr]Zr-DFO-CD4 signal on day 2. All the images are processed at the same setting and decay corrected to the imaging time. F) Day6/day0 intratumoral [⁸⁹Zr]Zr-DFO-CD4 SUV_mean of each treatment group in the 4T1 model. α-PD-1 treated responders showed a significant increase of [⁸⁹Zr]Zr-DFO-CD4 SUV_mean. G) Representative images of [⁸⁹Zr]-CD4 PET from day 0 to day 6 in the combinational treatment group in the 4T1 model. The responder showed a slight increase in [⁸⁹Zr]-CD4 signal on day 2. H) Day6/day0 intratumoral [89Zr]-CD4 SUV_mean of each treatment group in 4T1 model. α-PD-1 treated responders showed a significant increase of [⁸⁹Zr]-CD4 SUV_mean