Expansion of Lymphocytes from Prostatic Adenocarcinoma and Adjacent Nonmalignant Tissue.

Background: The evaluation of tumour-infiltrating lymphocytes (TILs) in solid malignancies has yielded insights into immune regulation within the tumour microenvironment and has also led to the development and optimisation of adoptive T cell therapies.

Objectives: This study examined the expansion of TILs from prostate adenocarcinoma, as a preliminary step to evaluate the potential of TILs for adoptive T cell therapy. . Malignant and adjacent nonmalignant tissues were obtained from fifteen men undergoing radical prostatectomy. . There were no study interventions. . Expanded cells were analysed by flow cytometry, and the data was assessed for associations between cell subpopulations and expansion rate.

Results: Tumour-infiltrating lymphocytes could be expanded to numbers that would be needed to generate a therapeutic infusion product from nine of 15 malignant specimens (60%). The CD4 T cells predominated over CD8 T cells (median 56.8% CD4, 30.0% CD8), and furthermore, faster TIL expansion was associated with a higher proportion of CD4 T cells (median 69.8% in faster-growing cultures; 36.8% in slower-growing cultures). A higher proportion of CD3CD56 cells versus CD3 cells was associated with slower TIL expansion in cultures from malignant specimens (median 13.3% in slower-growing cultures versus 2.05% in faster-growing cultures), but not from nonmalignant specimens.

Conclusions: The expansion of TILs for potential therapeutic use is feasible. Our findings also indicate that further examination of TILs from prostate adenocarcinomas may yield insights into mechanisms of regulation of T cells within the tumour microenvironment. Further research is required to evaluate their therapeutic potential.