{"entity":{"id":"tnbc-basal-like-1","kind":"cancer","name":"Basal-like 1 triple-negative breast cancer (BL1)","aka":["BL1 subtype","Basal-like 1 TNBC","Cell-cycle and DNA damage response subtype of TNBC"],"tldr":"Basal-like 1 is the subtype of triple-negative breast cancer whose cancer cells are busiest dividing and worst at repairing DNA. In the studies that defined it, these tumours were the most likely to disappear completely with chemotherapy before surgery, about four in ten, and their cell lines responded best to platinum drugs.","summary":"Lehmann and colleagues analysed gene expression from 587 triple-negative cancers across 21 datasets and found six clusters; basal-like 1 (BL1) and basal-like 2 (BL2) had higher expression of cell-cycle and DNA damage response genes, and cell lines representing them preferentially responded to cisplatin (Lehmann 2011). The 2016 refinement to four tumour-specific subtypes (BL1, BL2, M and LAR) kept BL1 and showed the subtypes differ in age at diagnosis, grade, progression and histopathology; across five neoadjuvant chemotherapy datasets, 41 percent of BL1 patients reached a pathological complete response against 18 percent for BL2 and 29 percent for LAR (Lehmann 2016). In the MD Anderson series of 130 patients the BL1 subtype had the highest pathological complete response rate, 52 percent (Masuda 2013). Burstein's independent four-way classification splits the basal-like tumours by immune state instead, into basal-like immune-activated (best prognosis) and basal-like immunosuppressed (worst) (Burstein 2015). The DNA repair signature is why BL1 tumours are the natural home of the homologous recombination deficiency biology described in the glossary: HR-deficient triple-negative tumours had pathological complete response rates of 63.5 percent with carboplatin against 33.9 percent without in GeparSixto (Loibl 2018).\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":"Masuda, Clin Cancer Res 2013: differential response to neoadjuvant chemotherapy among 7 triple-negative subtypes","url":"https://doi.org/10.1158/1078-0432.ccr-13-0799"},{"label":"Burstein, Clin Cancer Res 2015: four triple-negative subtypes (LAR, MES, BLIS, BLIA) with distinct prognoses","url":"https://doi.org/10.1158/1078-0432.ccr-14-0432"},{"label":"Loibl, Ann Oncol 2018: GeparSixto survival and HRD score as predictor of response","url":"https://doi.org/10.1093/annonc/mdy460"}],"tags":["breast","tnbc","subtype-page"],"related":["tnbc","tnbc-basal-like-2","brca-associated-tnbc","tnbc-early"],"cancers":[],"sections":[],"technologies":[],"targets":["brca","parp","tp53"],"drugs":[],"companies":[],"institutions":[],"pathways":["ddr","p53-cell-cycle"],"terms":["basal-like","hrd-in-breast-cancer","pcr"],"trials":["geparsixto","keynote-522"],"people":[],"bottlenecks":[],"keyPapers":[],"journals":[],"dependsOn":[],"notes":[],"group":"breast","burden":"One of the four tumour-intrinsic triple-negative subtypes in the refined Lehmann classification; the share varies by cohort and the classification is used in research, not in NHS pathology reports.","subtypes":["Basal-like immune-activated (BLIA, Burstein 2015; best prognosis)","Basal-like immunosuppressed (BLIS, Burstein 2015; worst prognosis)"],"biomarkers":["Cell-cycle and DNA damage response gene expression (research)","HRD score of 42 or more or tumour BRCA mutation, the response marker for platinum in GeparSixto","Germline BRCA1 (enriched in basal-like disease)"],"standardOfCare":[{"setting":"Stage II to III","approach":"As for triple-negative disease: pembrolizumab with carboplatin and paclitaxel then an anthracycline before surgery (KEYNOTE-522); the subtype is not used to choose treatment.","refs":["keynote-522","pembrolizumab","carboplatin","platinum"]}],"stateOfArt":[],"history":[],"pipeline":[],"openProblems":[],"parent":"tnbc"},"route":"/cancers/tnbc-basal-like-1/","neighbours":{"cancer":[{"id":"tnbc-basal-like-2","kind":"cancer","name":"Basal-like 2 triple-negative breast cancer (BL2)","route":"/cancers/tnbc-basal-like-2/"},{"id":"brca-associated-tnbc","kind":"cancer","name":"BRCA-associated triple-negative breast cancer","route":"/cancers/brca-associated-tnbc/"},{"id":"tnbc-early","kind":"cancer","name":"Early triple-negative breast cancer","route":"/cancers/tnbc-early/"},{"id":"tnbc-immunomodulatory","kind":"cancer","name":"Immunomodulatory triple-negative breast cancer (IM)","route":"/cancers/tnbc-immunomodulatory/"},{"id":"tnbc-luminal-androgen-receptor","kind":"cancer","name":"Luminal androgen receptor triple-negative breast cancer (LAR)","route":"/cancers/tnbc-luminal-androgen-receptor/"},{"id":"tnbc","kind":"cancer","name":"Triple-negative breast cancer (TNBC)","route":"/cancers/tnbc/"}],"target":[{"id":"brca","kind":"target","name":"BRCA1 / BRCA2 (HRD)","route":"/targets/brca/"},{"id":"parp","kind":"target","name":"PARP","route":"/targets/parp/"},{"id":"tp53","kind":"target","name":"TP53","route":"/targets/tp53/"}],"pathway":[{"id":"ddr","kind":"pathway","name":"DNA damage response & homologous recombination","route":"/pathways/ddr/"},{"id":"p53-cell-cycle","kind":"pathway","name":"p53 / RB / cell-cycle checkpoint","route":"/pathways/p53-cell-cycle/"}],"term":[{"id":"basal-like","kind":"term","name":"Basal-like breast cancer","route":"/terms/basal-like/"},{"id":"hrd-in-breast-cancer","kind":"term","name":"Homologous recombination deficiency (HRD) in breast cancer","route":"/terms/hrd-in-breast-cancer/"},{"id":"pcr","kind":"term","name":"Pathologic complete response (pCR)","route":"/terms/pcr/"}],"trial":[{"id":"geparsixto","kind":"trial","name":"GeparSixto","route":"/trials/geparsixto/"},{"id":"keynote-522","kind":"trial","name":"KEYNOTE-522","route":"/trials/keynote-522/"}],"drug":[{"id":"carboplatin","kind":"drug","name":"Carboplatin","route":"/drugs/carboplatin/"},{"id":"pembrolizumab","kind":"drug","name":"Pembrolizumab","route":"/drugs/pembrolizumab/"}],"technology":[{"id":"platinum","kind":"technology","name":"Platinum agents","route":"/technologies/platinum/"}]}}