Spanish team reverses pancreatic tumors in mice

Spanish researchers at the National Cancer Research Centre, or CNIO, said on January 29 that a three-drug strategy had completely eliminated pancreatic tumors in mice and prevented resistance in animal models. The work, led by Mariano Barbacid and published in the Proceedings of the National Academy of Sciences, was presented as a preclinical advance against pancreatic ductal adenocarcinoma, the most common form of pancreatic cancer. A social-media roundup recirculated the claim this week, but the underlying paper was retracted by PNAS on April 27. The journal said the retraction was tied to an undisclosed competing interest, not to a stated failure of the mouse results themselves. ### Which Spanish team was behind the mouse study? CNIO identified Mariano Barbacid, head of its Experimental Oncology Group, as the lead scientist on the work. CNIO’s January 29 release said Carmen Guerra was co-lead author and Vasiliki Liaki and Sara Barrambana were first authors on the paper. The study focused on pancreatic ductal adenocarcinoma, or PDAC, which CNIO described as the most common type of pancreatic cancer. (cnio.es) PNAS named the full paper as “A targeted combination therapy achieves effective pancreatic cancer regression and prevents tumor resistance.” The retraction notice listed Liaki, Barrambana and Guerra among the authors, alongside Barbacid and other collaborators. ### What did the treatment reportedly do in mice? CNIO said the therapy “successfully eliminates pancreatic tumours in mice completely and durably, with no significant side effects.” The institute said the strategy aimed to stop the KRAS pathway at three points instead of one, after single-target approaches had been limited by resistance. (cnio.es) (pnas.org) CNIO also said the tumors “disappeared permanently” after the group genetically eliminated three molecules from the KRAS signaling pathway in mouse models. In its public description, the institute said the work opened the way to designing new combination therapies, though it described the findings as preclinical. (cnio.es) ### What was in the triple-therapy approach? CNIO’s January 29 account said the group’s strategy was to block KRAS signaling at three points. The release did not, in the lines retrieved, fully list the drug names, but multiple secondary reports describing the same paper said the approach targeted downstream RAF1, upstream EGFR and orthogonal STAT3 signaling. Those reports matched CNIO’s description of a three-point blockade of the KRAS pathway. (cnio.es) CNIO’s Experimental Oncology Group page says the lab studies therapeutic strategies against KRAS-mutant lung and pancreatic tumors and has reported complete tumor regressions in preclinical models after KRAS-pathway interventions. That page does not substitute for the retracted paper, but it places the mouse work within the group’s longer-running KRAS research program. (cnio.es) ### Why was the paper retracted? PNAS said on April 27 that editors were retracting the article because of “an undisclosed relevant competing interest at the time of submission.” The notice said Barbacid and two coauthors, Liaki and Guerra, held financial interests in Vega Oncotargets. CNIO’s own January 29 news release now carries a warning at the top stating that the news item refers to a paper that “has been retracted.” The institute repeats the explanation from the journal that the issue involved the undisclosed competing interest. (cnio.es) ### So how should readers treat the claim now? (pnas.org) The April 27 retraction means the paper is no longer part of the active peer-reviewed literature in its original form. The mouse results continue to circulate online, but any standalone account of the study now needs to note that PNAS withdrew the article over disclosure issues involving financial interests. (cnio.es) PNAS hosts the retraction notice, and CNIO’s public release remains online with the retraction warning attached. Those two records are the current reference points for the study as of May 23, 2026. (cnio.es) (pnas.org)