Table 2.

Summary of key bulk transcriptomic studies of pancreatic cancer that have yielded the classical/epithelial vs. basal-like/quasi-mesenchymal/squamous consensus subtypes.

Study	Technique(s)	Sample Size	Key Findings
Collisson et al, Nature Medicine 2011 (25)	Microarray	27 microdissected 36 PDAC tumors, previously published	Non-negative matrix factorization and consensus clustering yields three subtypes: classical, quasi-mesenchymal, and exocrine-like
Moffitt et al, Nature Genetics 2015 (26)	Microarray	145 primary 61 metastatic 17 cell lines	Identification of classical and basal-like subtype, with the latter exhibiting poorer survival
Bailey et al, Nature 2016 (27)	RNA-seq Microarray	96 RNA-seq 232 microarray	Unsupervised clustering of RNA-seq data from 96 tumors with at least 40% epithelial content yielded four subtypes: squamous, pancreatic progenitor, immunogenic, aberrantly differentiated endocrine exocrine (ADEX); additionally examined 232 tumors with microarray data (median cellularity 30%)
Raphael et al, Cancer Cell 2017 (19)	RNA-seq	150	Reconciliation of previously identified subtypes; found that high-purity tumors can consistently be classified into either basal-like/squamous or classical/progenitor
Puleo et al, Gastroenterology 2020 (28)	Microarray	309	Validated basal-like vs. classical distinction found from prior studies. Incorporated consideration of microenvironment, which yielded five subtypes: pure basal-like, stroma activated, desmoplastic, pure classical, and immune classical