# Basal-like 1 triple-negative breast cancer (BL1)

Source: https://onco.cc/cancers/tnbc-basal-like-1/  
OnCo record `tnbc-basal-like-1` (Cancer). Data CC BY-NC 4.0, attribute "Data from OnCo (onco.cc)"; commercial use needs a licence.

## TL;DR

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).

A 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.

## Fields

- Kind: Cancer
- Last checked: 2026-09-24
- Also known as: BL1 subtype; Basal-like 1 TNBC; Cell-cycle and DNA damage response subtype of TNBC
- Tags: breast; tnbc; subtype-page
- 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)

## Sections of this record

The page is a hub with ten sections in reading order; large sections have their own page. The same plan as JSON: https://onco.cc/api/v1/cancers/tnbc-basal-like-1/sections.json

- Overview (on the hub): The TL;DR, the family this cancer belongs to, the organ, who gets it and what the state of the art is. https://onco.cc/cancers/tnbc-basal-like-1/#overview
- What it is (on the hub): Anatomy, the subtypes and how they differ, how it is staged, and where advanced disease spreads. https://onco.cc/cancers/tnbc-basal-like-1/#what-it-is [2 subtypes]
- Finding it (on the hub): How it shows itself, how it is confirmed, what screening exists, and the biomarkers clinicians test for. https://onco.cc/cancers/tnbc-basal-like-1/#finding-it [3 biomarkers]
- Treating it (on the hub): The standard of care by setting, the medicines, surgery and radiotherapy named in it, and the regimens behind them. https://onco.cc/cancers/tnbc-basal-like-1/#treating-it [1 setting, 1 decision with options]
- Evidence (on the hub): Trials recruiting now, the landmark trials, the key papers and what they mean, the latest literature, and the milestones year by year. https://onco.cc/cancers/tnbc-basal-like-1/#evidence [2 trials]
- The science (on the hub): The molecular landscape: the targets and how often each appears, the pathways, the mechanics stages and the preclinical models. https://onco.cc/cancers/tnbc-basal-like-1/#science [4 targets, 2 pathways]
- Where you are (own page): Cases by country, the UK and NHS pathway and other country lenses, and the expert centres with trials on record. https://onco.cc/cancers/tnbc-basal-like-1/where-you-are/
- Living with it (on the hub): The decisions you may face, the aids that walk through them, the warnings on record, the first sixty days and the questions to ask. https://onco.cc/cancers/tnbc-basal-like-1/#living-with-it [9 questions, 6 red cards]
- What is coming (own page): Everything in development, the open problems and what is being done about them, the roadmaps, and what changed on this record. https://onco.cc/cancers/tnbc-basal-like-1/coming/ [2 medicines]
- Data (own page): Every connected record, the notes, the JSON, Markdown and RDF twins, and where the record came from and when it was checked. https://onco.cc/cancers/tnbc-basal-like-1/data/ [18 connected records]

## Standard of care

- Stage II to III: 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. ([KEYNOTE-522](https://onco.cc/trials/keynote-522/), [Pembrolizumab](https://onco.cc/drugs/pembrolizumab/), [Carboplatin](https://onco.cc/drugs/carboplatin/), [Platinum agents](https://onco.cc/technologies/platinum/))

## Sources

- Wikipedia: https://en.wikipedia.org/wiki/Triple-negative_breast_cancer
- Lehmann, J Clin Invest 2011: identification of human triple-negative breast cancer subtypes (BL1, BL2, IM, M, MSL, LAR): https://doi.org/10.1172/jci45014
- Lehmann, PLoS One 2016: refinement of triple-negative breast cancer molecular subtypes to four (TNBCtype-4): https://doi.org/10.1371/journal.pone.0157368
- Masuda, Clin Cancer Res 2013: differential response to neoadjuvant chemotherapy among 7 triple-negative subtypes: https://doi.org/10.1158/1078-0432.ccr-13-0799
- Burstein, Clin Cancer Res 2015: four triple-negative subtypes (LAR, MES, BLIS, BLIA) with distinct prognoses: https://doi.org/10.1158/1078-0432.ccr-14-0432
- Loibl, Ann Oncol 2018: GeparSixto survival and HRD score as predictor of response: https://doi.org/10.1093/annonc/mdy460

## Connected records

- cancers: [Basal-like 2 triple-negative breast cancer (BL2)](https://onco.cc/cancers/tnbc-basal-like-2/), [BRCA-associated triple-negative breast cancer](https://onco.cc/cancers/brca-associated-tnbc/), [Early triple-negative breast cancer](https://onco.cc/cancers/tnbc-early/), [Immunomodulatory triple-negative breast cancer (IM)](https://onco.cc/cancers/tnbc-immunomodulatory/), [Luminal androgen receptor triple-negative breast cancer (LAR)](https://onco.cc/cancers/tnbc-luminal-androgen-receptor/), [Triple-negative breast cancer (TNBC)](https://onco.cc/cancers/tnbc/)
- targets: [BRCA1 / BRCA2 (HRD)](https://onco.cc/targets/brca/), [PARP](https://onco.cc/targets/parp/), [TP53](https://onco.cc/targets/tp53/)
- pathways: [DNA damage response & homologous recombination](https://onco.cc/pathways/ddr/), [p53 / RB / cell-cycle checkpoint](https://onco.cc/pathways/p53-cell-cycle/)
- terms: [Basal-like breast cancer](https://onco.cc/terms/basal-like/), [Homologous recombination deficiency (HRD) in breast cancer](https://onco.cc/terms/hrd-in-breast-cancer/), [Pathologic complete response (pCR)](https://onco.cc/terms/pcr/)
- trials: [GeparSixto](https://onco.cc/trials/geparsixto/), [KEYNOTE-522](https://onco.cc/trials/keynote-522/)
- drugs: [Carboplatin](https://onco.cc/drugs/carboplatin/), [Pembrolizumab](https://onco.cc/drugs/pembrolizumab/)
- technologies: [Platinum agents](https://onco.cc/technologies/platinum/)

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JSON: https://onco.cc/api/v1/entities/tnbc-basal-like-1.json