Purpose: Compare pancreatic ductal adenocarcinoma (PDAC), preclinical models, by their transcriptome and drug response landscapes to evaluate their complementarity. Experimental Design: Three paired PDAC preclinical models—patient-derived xenografts (PDX), xenograft-derived pancreatic organoids (XDPO) and xenograft-derived primary cell cultures (XDPCC)—were derived from 20 patients and analyzed at the transcriptomic and chemosensitivity level. Transcriptomic characterization was performed using the basal-like/classical subtyping and the PDAC molecular gradient (PAMG). Chemosensitivity for gemcitabine, irinotecan, 5-fluorouracil and oxaliplatin was established and the associated biological pathways were determined using independent component analysis (ICA) on the transcriptome of each model. The selection criteria used to identify the different components was the chemosensitivity score (CSS) found for each drug in each model. Results: PDX was the most dispersed model whereas XDPO and XDPCC were mainly classical and basal-like, respectively. Chemosensitivity scoring determines that PDX and XDPO display a positive correlation for three out of four drugs tested, whereas PDX and XDPCC did not correlate. No match was observed for each tumor chemosensitivity in the different models. Finally, pathway analysis shows a significant association between PDX and XDPO for the chemosensitivity-associated pathways and PDX and XDPCC for the chemoresistance-associated pathways. Conclusions: Each PDAC preclinical model possesses a unique basal-like/classical transcriptomic phenotype that strongly influences their global chemosensitivity. Each preclinical model is imperfect but complementary, suggesting that a more representative approach of the clinical reality could be obtained by combining them. Translational Relevance: The identification of molecular signatures that underpin drug sensitivity to chemotherapy in PDAC remains clinically challenging. Importantly, the vast majority of studies using preclinical in vivo and in vitro models fail when transferred to patients in a clinical setting despite initially promising results. This study presents for the first time a comparison between three preclinical models directly derived from the same patients. We show that their applicability to preclinical studies should be considered with a complementary focus, avoiding tumor-based direct extrapolations, which might generate misleading conclusions and consequently the overlook of clinically relevant features.

Table S1 from DNMT3B Plays Antagonistic Roles with SMARCB1 and Is a Targetable Vulnerability in Rhabdoid Tumors

Purpose: Rhabdoid tumors (RT) are highly aggressive pediatric cancers driven by the biallelic inactivation of the SMARCB1 tumor-suppressor gene, the sole recurrent genetic alteration. SMARCB1 encodes a core subunit of the SWI/SNF chromatin remodeling complex; its loss disrupts epigenetic gene regulation, supporting the classification of RT as prototypical epigenetically driven cancers and highlighting the therapeutic potential of targeting epigenetic modifiers. Notably, previous studies have reported the overexpression of DNMT3A and DNMT3B, enzymes responsible for de novo DNA methylation, in RT. Experimental Design: Using patient samples, cell lines, and an ex vivo brain organoid system, combined with immunohistochemistry and bioinformatics, we investigated the role of DNMT3 enzymes in RT progression. Results: In a composite tumor case, SMARCB1-deficient and -proficient regions displayed distinct methylation profiles. SMARCB1 loss correlated with increased DNA methylation and DNMT3A/B overexpression. To assess their respective roles in RT, we used CRISPR–Cas9 to knock out DNMT3A/B in a SMARCB1-inducible RT cell line. DNMT3B loss impaired viability more strongly than DNMT3A. DNMT3B knockout and SMARCB1 reexpression regulated overlapping gene programs related to development and cell adhesion at methylation and transcriptional levels. We next demonstrated that the cytotoxicity of the DNMT inhibitor decitabine, which impairs RT cell growth in human induced-pluripotent stem cell-derived cerebral organoids, is primarily mediated by DNMT3B. Conclusions: These results show that DNMT3B plays a key role in the cascade of epigenetic effects following SMARCB1 loss and is pivotal to RT sensitivity to decitabine; our study, therefore, supports the development of DNMT3B-specific inhibitors for RT.