Three Molecular Developmental Pathways of Remnant Pancreatic Cancer after Resection: A Nationwide Project Study of Japan Pancreas Society.

OBJECTIVE: This study aimed to clarify the molecular mechanism of remnant pancreatic cancer (PC) development after primary PC resection. SUMMARY BACKGROUND DATA: Molecular mechanisms of the development of remnant PCs following primary PC resection are largely unknown. METHODS: Forty-three patients undergoing remnant PC resection after primary PC resection between 2001 and 2017 at 26 institutes were retrospectively analyzed. Clinicopathological features and molecular alterations detected by targeted amplicon sequencing of 36 PC-associated genes were evaluated. RESULTS: These patients showed significantly lower body mass indices and higher hemoglobin A1c values at remnant PC resection than at primary PC resection. A comparison of the molecular features between primary and remnant PCs indicated that remnant PCs were likely to develop via three different molecular pathways: successional, showing identical and accumulated alterations (n=14); phylogenic, showing identical and distinct alterations (n=26); and distinct, showing independent distinctive alterations (n=3). The similarity of gene alterations was associated with time to the remnant PC development (r=－0.384, P=0.0173). Phylogenic pathways were significantly associated with the intraductal spread of carcinoma (P=0.007). Patient survival did not differ significantly depending on these molecular pathways. CONCLUSION: Molecular profiling uncovered three pathways for the development of remnant PCs, namely, successional, phylogenic, and distinct pathways. The vast majority of remnant PCs are likely to be molecularly associated with primary PCs either in the successional or phylogenic way. This information could impact the design of a strategy for monitoring and treating remnant PCs.

Gene Rearrangement and Expression of PRKACA and PRKACB Govern Morphobiology of Pancreatobiliary Oncocytic Neoplasms.

Intraductal oncocytic papillary neoplasms (IOPNs) are distinct from intraductal papillary mucinous neoplasms based on characteristic morphologic and genetic features represented by fusion genes involving PRKACA or PRKACB (PRKACA/B). However, pancreatic and biliary tumors with partial oncocytic features are often encountered clinically, and their molecular features are yet to be clarified. This study included 80 intraductal papillary neoplasms: 32 tumors with mature IOPN morphology (typical), 28 with partial or subclonal oncocytic features (atypical), and 20 without oncocytic features (control). We analyzed PRKACA/B fusion genes, including ATP1B1::PRKACA, DNAJB1::PRKACA, and ATP1B1::PRKACB, by reverse-transcription PCR; mRNA expression of fusion genes and nonrearranged PRKACA/B genes by quantitative reverse-transcription PCR; mutations in KRAS, BRAF, and GNAS by targeted sequencing or droplet digital PCR; and the expression of cyclic adenosine monophosphate (cAMP)-dependent protein kinase catalytic subunits α (PRKACA) and ß (PRKACB), phosphorylated cAMP response element-binding protein, and aberrations of p16, p53, SMAD4, STK11, and ß-catenin by immunohistochemistry. PRKACA/B fusion genes were detected in 100% (32/32) of typical, 46% (13/28) of atypical, and 0% (0/20) of control (P < .05). Expression of PRKACA, PRKACB, and phosphorylated cAMP response element-binding protein was upregulated in neoplasms with PRKACA/B fusion genes (P < .05). mRNA expression of the PRKACA/B fusion genes and protein expression of PRKACA or PRKACB tended to be higher in typical than in atypical cases (mRNA, P = .002; protein expression, P = .054). In some atypical neoplasms with mixed subtypes, PRKACA/B fusion genes were superimposed exclusively on oncocytic components. Typical IOPNs harbored fewer KRAS and GNAS mutations than control samples and fewer alterations in p53 and STK11 than atypical samples (P < .05). In conclusion, PRKACA/B fusion genes not only are the characteristic drivers of IOPNs but also play a crucial role in the development of subclonal oncocytic neoplasms. Moreover, oncocytic morphology is strongly associated with upregulation of PRKACA/B, which may provide clues for potential therapeutic options.

Salivary gland cancer organoids are valid for preclinical genotype-oriented medical precision trials.

Salivary gland cancers (SGCs) are heterogeneous tumors, and precision oncology represents a promising therapeutic approach; however, its impact on SGCs remains obscure. This study aimed to establish a translational model for testing molecular-targeted therapies by combining patient-derived organoids and genomic analyses of SGCs. We enrolled 29 patients, including 24 with SGCs and 5 with benign tumors. Resected tumors were subjected to organoid and monolayer cultures, as well as whole-exome sequencing. Organoid and monolayer cultures of SGCs were successfully established in 70.8% and 62.5% of cases, respectively. Organoids retained most histopathological and genetic profiles of their original tumors. In contrast, 40% of the monolayer-cultured cells did not harbor somatic mutations of their original tumors. The efficacy of molecular-targeted drugs tested on organoids depended on their oncogenic features. Organoids recapitulated the primary tumors and were useful for testing genotype-oriented molecular targeted therapy, which is valuable for precision medicine in patients with SGCs.