Bulk transcriptomic classifiers have historically stratified pancreatic ductal adenocarcinoma (PDAC) into classical and basal-like subtypes with prognostic and therapeutic relevance. However, increasing evidence indicates that these epithelial programs often coexist within individual tumors. How intermediate or coexisting epithelial states shape the local tumor microenvironment and immune function at spatial scales relevant to cell-cell interactions has remained unclear. The authors aimed to resolve epithelial subtype identity in space and to quantify associated microenvironments at the level of spatially contiguous cancer nests.
The study integrates multiplexed ion beam imaging (MIBI) with bulk RNA sequencing to connect single-cell, spatially resolved epithelial states to transcriptional ecotypes derived from bulk data. This combined approach permits delineation of epithelial programs at single-cell resolution while retaining spatial context for analysis of proximal immune and stromal cell states.
Across 47 primary tumor samples from 34 patients, the investigators identified three epithelial states at single-cell resolution: classical, intermediate, and basal. These cancer cells were organized into spatially contiguous structures the authors call cancer nests. Cancer nests varied in composition: some were dominated by a single epithelial program while others displayed mixed subtype compositions, demonstrating intratumoral heterogeneity that is spatially organized rather than uniformly distributed.
Using distance-resolved spatial metrics, the authors examined how epithelial subtype composition relates to nearby immune states. They report that basal-rich cancer nests are surrounded by locally immunosuppressive microenvironments. Specifically, myeloid cells proximal to basal-rich nests showed reduced expression of MHC class II and co-stimulatory molecules, indicative of impaired myeloid antigen presentation. Importantly, this impairment in antigen presentation signatures occurred independent of overall myeloid cell abundance, suggesting a functional suppression of myeloid antigen-presenting capacity rather than simple exclusion or depletion of myeloid cells.
The regions surrounding basal-rich nests were enriched in fibroblast-dominated neighborhoods and displayed distinct cell-cell interaction architectures. These spatial neighborhoods suggest that stromal composition and local interaction patterns contribute to the observed myeloid dysfunction and immunosuppressive milieu near basal epithelial programs.
To relate spatially resolved niche phenotypes to patient-level transcriptional states, the authors applied EcoTyper analysis to two independent bulk RNA-seq cohorts: an OHSU discovery cohort (N = 277 patients) and The Cancer Genome Atlas (TCGA) as a validation cohort (N = 147 patients). They identified tumor ecotypes associated with poor prognosis that were enriched for basal epithelial states and that exhibited depleted myeloid antigen presentation signatures. This linkage connects spatial niche phenotypes observed by MIBI to broader bulk transcriptional ecotypes and clinical outcomes.
Taken together, the data indicate that epithelial subtype programs in PDAC are organized at the level of spatially defined cancer nests and that basal epithelial programs preferentially reside within localized niches of myeloid antigen presentation dysfunction. The spatial association between basal programs, fibroblast-rich neighborhoods, and impaired myeloid antigen presentation provides a mechanistic connection between intratumoral architecture, immune suppression, and patient prognosis as revealed by ecotype analysis of bulk cohorts.
This summary is based on the abstract and front-matter of the preprint. The article is a preprint and has not been certified by peer review. Methodological details beyond those described in the abstract—such as specific marker panels used for MIBI, statistical models for distance-resolved analyses, patient clinical characteristics, and full cohort demographics—were not reported in the source text provided here. Additional experimental validation, mechanistic interrogation, or therapeutic implications beyond the associations described were not detailed in the abstract.
The integrated spatial and bulk transcriptomic approach described links epithelial subtype heterogeneity in PDAC to localized immunosuppressive niches characterized by impaired myeloid antigen presentation, particularly around basal-rich cancer nests. These spatial niche phenotypes correspond to poor-prognosis ecotypes in independent bulk cohorts, highlighting the importance of intratumoral architecture in shaping immune suppression and clinical outcome in PDAC.