We have developed 3D-tumoroids and tumor slice in vitro culture systems from 
surgical tumor specimens derived from patients with colorectal cancer (CRC) or 
lung cancer to evaluate immune cell populations infiltrating cultured tissues. 
The system incorporates patient's peripherally and tumor-derived immune cells 
into tumoroid in vitro cultures to evaluate the ability of the culture to mimic 
an immunosuppressive tumor microenvironment (ITM). This system enables analysis 
of tumor response to standard therapy within weeks of surgical resection. Here 
we show that tumoroid cultures from a CRC patient are highly sensitive to the 
thymidylate synthase inhibitor 5-fluorouracil (adrucil) but less sensitive to 
the combination of nucleoside analog trifluridine and thymidine phosphorylase 
inhibitor tipiracil (Lonsurf). Moreover, re-introduction of isolated immune 
cells derived from surrounding and infiltrating tumor tissue as well as CD45+ 
tumor infiltrating hematopoietic cells displayed prolonged (>10 days) survival 
in co-culture. Established tumor slice cultures were found to contain both an 
outer epithelial and inner stromal cell compartment mimicking tumor structure in 
vivo. Collectively, these data suggest that, 3D-tumoroid and slice culture 
assays may provide a feasible in vitro approach to assess efficacy of novel 
therapeutics in the context of heterogeneous tumor-associated cell types 
including immune and non-transformed stromal cells. In addition, delineating the 
impact of therapeutics on immune cells, and cell types involved in therapeutic 
resistance mechanisms may be possible in general or for patient-specific 
responses.