(A) Morphological changes in PDOs after 48 hours of in vitro treatment with vehicle (Control) alone, vehicle (Control) in co-cultures with CTLs (Condition 1), nivolumab (0.5 μg/ml; Condition 2) or Cabozantinib (10 μM; Condition 3) in co-cultures with CTLs, nivolumab (Condition 4) or a combination of nivolumab and Cabozantinib (Condition 5) in co-cultures with CTLs and MDSCs. (B) Images showing changes in organoid viability and CD8+ cell expression in organoid co-cultures. (C) Measurement of changes in CTL proliferation by CFSE, with quantification shown in (D). Changes in (D) perforin expression in CTLs, (E) percent of viable EpCAM+/PD-L1+ organoids and (F) PMN-MDSCs in response to treatments. *p<0.05 compared to condition 1, n = 4 organoid co-cultures derived from individual patients.