Clonal heterogeneity leads to secondary resistance in a melanoma patient after adoptive cell therapy with tumor-infiltrating lymphocytes

Adoptive cell therapy (ACT) with tumor-infiltrating lymphocytes (TIL) is effective in melanoma patients, although long-term responses seem restricted to patients with complete remissions. Many patients develop secondary resistance to TIL-ACT but involved mechanisms are unclear. Here, we describe a case of secondary resistance to TIL-ACT likely due to intratumoral heterogeneity and selection of a resistant tumor cell clone via transferred T cells. This is the first case of clonal selection of a pre-existing non-dominant tumor cell clone and demonstrates a new mechanism involved in secondary resistance to TIL-ACT and could potentially change current clinical practice, because it advocates for T cell collection from different tumor sites and analysis of tumor heterogeneity before the treatment with TIL-ACT.

Type: Transcriptome Analysis
Archiver: European Genome-Phenome Archive (EGA)

1 Dataset

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Dataset ID	Description	Technology	Samples
EGAD50000000406	scRNA sequencing and scTCR sequencing on three tumor lesions derived from one patient receiving adoptive tumor-infiltrating lymphocyte (TIL) therapy. Expanded metastasis was used for TIL expansion and yielded the TIL product which also was used for scTCR sequencing. 10 weeks after transfer of the TIL product the regressing metastasis was resected. After the patient progressed the progressing metastasis was removed (61 weeks).	Illumina NovaSeq 6000	4