{"entity":{"id":"tnbc-mesenchymal-stem-like","kind":"cancer","name":"Mesenchymal stem-like triple-negative breast cancer (MSL)","aka":["MSL subtype","Mesenchymal stem-like TNBC"],"tldr":"Mesenchymal stem-like was one of the six original subtypes of triple-negative breast cancer, marked by stem-cell and low-proliferation genes. Five years later the same group showed the signal came from stromal cells mixed into the sample rather than the cancer cells, so the label describes a tumour environment rather than a tumour.","summary":"Lehmann 2011 separated a mesenchymal stem-like (MSL) cluster from the mesenchymal cluster by lower expression of proliferation genes and enrichment for genes of mesenchymal stem cells, angiogenesis and growth factor signalling; representative cell lines responded to the PI3K/mTOR inhibitor NVP-BEZ235 and to dasatinib (Lehmann 2011). Using histopathological quantification and laser-capture microdissection, the 2016 refinement showed that the MSL transcripts were contributed by tumour-associated stromal cells, as the immunomodulatory transcripts were by infiltrating lymphocytes, and collapsed the classification to four tumour-specific subtypes (Lehmann 2016). The page stays because the label persists in papers and reports; a tumour once called MSL would now be assigned to the mesenchymal or another intrinsic subtype, and its low proliferation and stromal richness match the claudin-low phenotype described by Fougner 2020.\n\nA research classification by gene expression (Lehmann 2011, refined 2016), not a test the NHS runs; treatment follows the triple-negative rows on the parent page.","asOf":"2026-09-24","wikipedia":"https://en.wikipedia.org/wiki/Triple-negative_breast_cancer","links":[{"label":"Lehmann, J Clin Invest 2011: identification of human triple-negative breast cancer subtypes (BL1, BL2, IM, M, MSL, LAR)","url":"https://doi.org/10.1172/jci45014"},{"label":"Lehmann, PLoS One 2016: refinement of triple-negative breast cancer molecular subtypes to four (TNBCtype-4)","url":"https://doi.org/10.1371/journal.pone.0157368"},{"label":"Fougner, Nat Commun 2020: re-definition of claudin-low as a breast cancer phenotype","url":"https://doi.org/10.1038/s41467-020-15574-5"}],"tags":["breast","tnbc","subtype-page"],"related":["tnbc","tnbc-mesenchymal","tnbc-immunomodulatory"],"cancers":[],"sections":[],"technologies":[],"targets":[],"drugs":[],"companies":[],"institutions":[],"pathways":["emt"],"terms":["claudin-low"],"trials":[],"people":[],"bottlenecks":[],"keyPapers":[],"journals":[],"dependsOn":[],"notes":[],"group":"breast","burden":"One of the six 2011 Lehmann subtypes; dropped as a tumour-intrinsic subtype in 2016 when its signal was traced to stromal cells.","subtypes":["Mesenchymal tumours with a stromal, low-proliferation signature (claudin-low phenotype)"],"biomarkers":["Stromal and mesenchymal stem-cell gene expression (a sample-composition signal, research only)"],"standardOfCare":[{"setting":"Any stage","approach":"As for triple-negative disease; the label has no treatment consequence.","refs":["pembrolizumab","keynote-522"]}],"stateOfArt":[],"history":[],"pipeline":[],"openProblems":[],"parent":"tnbc"},"route":"/cancers/tnbc-mesenchymal-stem-like/","neighbours":{"cancer":[{"id":"tnbc-immunomodulatory","kind":"cancer","name":"Immunomodulatory triple-negative breast cancer (IM)","route":"/cancers/tnbc-immunomodulatory/"},{"id":"tnbc-mesenchymal","kind":"cancer","name":"Mesenchymal triple-negative breast cancer (M)","route":"/cancers/tnbc-mesenchymal/"},{"id":"tnbc","kind":"cancer","name":"Triple-negative breast cancer (TNBC)","route":"/cancers/tnbc/"}],"pathway":[{"id":"emt","kind":"pathway","name":"Epithelial-mesenchymal transition & drug efflux","route":"/pathways/emt/"}],"term":[{"id":"claudin-low","kind":"term","name":"Claudin-low breast cancer","route":"/terms/claudin-low/"}],"drug":[{"id":"pembrolizumab","kind":"drug","name":"Pembrolizumab","route":"/drugs/pembrolizumab/"}],"trial":[{"id":"keynote-522","kind":"trial","name":"KEYNOTE-522","route":"/trials/keynote-522/"}]}}