Vaccine-Expanded Plasmablast-like B Cells Are Associated with Response to Dendritic Cell Therapy in Metastatic Melanoma

Dendritic cells (DCs), either monocyte-derived (moDCs) or naturally circulating, have been employed in cancer treatment across both metastatic and adjuvant settings. DC vaccines (DC Vax) are capable of inducing tumor-specific immune responses, yet clinical outcomes have thus far fallen short of expectations. Here, we performed a multi-omics analysis of the apheresis product, including CD14⁺ monocytes, and the final DCVax formulation. Among all the components analyzed, the most striking finding was the unexpected presence of CD19⁺ B cells within the DC Vax formulation, which distinguished Responders from Non-Responders to moDC vaccination in metastatic melanoma. The abundance of B cells in DC Vax correlated with their peripheral frequency; however, within the vaccine, these cells acquired a CD20lowCD27hiCD38hi plasmablast-like phenotype, distinct from their autologous circulating B-cell precursors. Notably, a parallel observation was made in Responders, whose pre-treatment lesions were enriched in B cells organized as Tertiary Lymphoid Structures. These results underscore the importance of B cells in both baseline immunity and DCVax formulation, hinting at unexplored mechanisms by which they may influence vaccine effectiveness.

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

2 Datasets

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Dataset ID	Description	Technology	Samples
EGAD50000001680	This dataset contains single-cell RNA-seq libraries prepared using the Chromium Single Cell 5' Library & Gel Bead Kit v1.1 (10x Genomics). Cells were partitioned into nanoliter-scale GEMs for barcoding and reverse transcription, followed by amplification and purification of cDNAs. Libraries were sequenced on an Illumina NovaSeq 6000 using 150 bp paired-end reads, ensuring high-resolution transcriptomic profiling.	Illumina NovaSeq 6000 NextSeq 550	34
EGAD50000001681	RNA libraries were prepared from 100 ng of total RNA using the Illumina Stranded Total RNA Prep with Ribo-Zero Plus kit, then sequenced (2×150 bp) on the Illumina NextSeq550. Transcript-level quantification was done with kallisto, followed by gene-level summarization (tximport) and differential expression analysis (DESeq2). Quality control included PCA, hierarchical clustering, and deconvolution with CIBERSORTx to exclude non-myeloid genes. Final analyses identified transcriptomic differences among healthy donors and three patient subgroups based on response to dendritic cell therapy.	NextSeq 550	27