TIL therapy broadens the tumor-reactive CD8⁺T cell compartment in melanoma patients

Abstract

There is strong evidence that both adoptive T cell transfer and T cell checkpoint blockade can lead to regression of human melanoma. However, little data are available on the effect of these cancer therapies on the tumor-reactive T cell compartment. To address this issue we have profiled therapy-induced T cell reactivity against a panel of 145 melanoma-associated CD8+ T cell epitopes. Using this approach, we demonstrate that individual tumor-infiltrating lymphocyte cell products from melanoma patients contain unique patterns of reactivity against shared melanoma-associated antigens, and that the combined magnitude of these responses is surprisingly low. Importantly, TIL therapy increases the breadth of the tumor-reactive T cell compartment in vivo, and T cell reactivity observed post-therapy can almost in full be explained by the reactivity observed within the matched cell product. These results establish the value of high-throughput monitoring for the analysis of immuno-active therapeutics and suggest that the clinical efficacy of TIL therapy can be enhanced by the preparation of more defined tumor-reactive T cell products.

HLA Micropolymorphisms Strongly Affect Peptide–MHC Multimer–Based Monitoring of Antigen-Specific CD8+ T Cell Responses

“…16). The melanoma-associated epitope panel consisting of 145 different peptides has been described previously (16).…”

“…To this purpose, we created a collection of HLA-A*02:01 pMHC multimers loaded with a set of 145 HLA-A*02:01-restricted melanomaassociated epitopes. Subsequently, CD8 + T cell responses against this set of epitopes were analyzed in TIL cultures from an HLA-A*02:06 + melanoma patient (HLA-A*02:01 and HLA-A*02:06 differ at position 9, F9Y) by combinatorial coding analysis (16). By performing the same analysis for this collection of epitopes complexed with HLA-A*02:06 multimers, it was possible to directly compare T cell reactivity as measured by use of subtype-matched and subtype-mismatched pMHC multimers.…”

“…For each peptide, pMHC-multimers were generated using two different fluorescent SA conjugates (Invitrogen) (16). T cell clones were stained with dual color-labeled pMHC multimers.…”

“…For combinatorial coding analyses, an 11-color instrument setting was used (16). To identify Ag-specific T cells, the following gating strategy was used: 1) selection of live (IR dye-negative) single-cell lymphocytes; 2) selection of anti-CD8-FITC + and "dump" (anti-CD4, -CD14, -CD16, -CD19; Invitrogen) negative cells; 3) selection of CD8 + T cells that were positive in two and only two pMHC multimer channels; and 4) cells positive in only one as well as cells positive in three or more pMHC multimer channels were gated out, as described previously (16).…”

Identification and Validation of Targets for Cancer Immunotherapy: From the Bench-to-Bedside

“…TILs are isolated, activated and expanded using IL-2 in vitro. The patient undergoes lympho-depleting chemotherapy prior to the T cells being injected back in to the blood [114].…”