The persistence of cancer cells resistant to therapy remains a major clinical challenge. In triple-negative breast cancer, resistance to chemotherapy results in the highest recurrence risk among ...breast cancer subtypes. The drug-tolerant state seems largely defined by nongenetic features, but the underlying mechanisms are poorly understood. Here, by monitoring epigenomes, transcriptomes and lineages with single-cell resolution, we show that the repressive histone mark H3K27me3 (trimethylation of histone H3 at lysine 27) regulates cell fate at the onset of chemotherapy. We report that a persister expression program is primed with both H3K4me3 (trimethylation of histone H3 at lysine 4) and H3K27me3 in unchallenged cells, with H3K27me3 being the lock to its transcriptional activation. We further demonstrate that depleting H3K27me3 enhances the potential of cancer cells to tolerate chemotherapy. Conversely, preventing H3K27me3 demethylation simultaneously to chemotherapy inhibits the transition to a drug-tolerant state, and delays tumor recurrence in vivo. Our results highlight how chromatin landscapes shape the potential of cancer cells to respond to initial therapy.
Summary Background Molecularly targeted agents have been reported to have anti-tumour activity for patients whose tumours harbour the matching molecular alteration. These results have led to ...increased off-label use of molecularly targeted agents on the basis of identified molecular alterations. We assessed the efficacy of several molecularly targeted agents marketed in France, which were chosen on the basis of tumour molecular profiling but used outside their indications, in patients with advanced cancer for whom standard-of-care therapy had failed. Methods The open-label, randomised, controlled phase 2 SHIVA trial was done at eight French academic centres. We included adult patients with any kind of metastatic solid tumour refractory to standard of care, provided they had an Eastern Cooperative Oncology Group performance status of 0 or 1, disease that was accessible for a biopsy or resection of a metastatic site, and at least one measurable lesion. The molecular profile of each patient's tumour was established with a mandatory biopsy of a metastatic tumour and large-scale genomic testing. We only included patients for whom a molecular alteration was identified within one of three molecular pathways (hormone receptor, PI3K/AKT/mTOR, RAF/MEK), which could be matched to one of ten regimens including 11 available molecularly targeted agents (erlotinib, lapatinib plus trastuzumab, sorafenib, imatinib, dasatinib, vemurafenib, everolimus, abiraterone, letrozole, tamoxifen). We randomly assigned these patients (1:1) to receive a matched molecularly targeted agent (experimental group) or treatment at physician's choice (control group) by central block randomisation (blocks of size six). Randomisation was done centrally with a web-based response system and was stratified according to the Royal Marsden Hospital prognostic score (0 or 1 vs 2 or 3) and the altered molecular pathway. Clinicians and patients were not masked to treatment allocation. Treatments in both groups were given in accordance with the approved product information and standard practice protocols at each institution and were continued until evidence of disease progression. The primary endpoint was progression-free survival in the intention-to-treat population, which was not assessed by independent central review. We assessed safety in any patients who received at least one dose of their assigned treatment. This trial is registered with ClinicalTrials.gov , number NCT01771458. Findings Between Oct 4, 2012, and July 11, 2014, we screened 741 patients with any tumour type. 293 (40%) patients had at least one molecular alteration matching one of the 10 available regimens. At the time of data cutoff, Jan 20, 2015, 195 (26%) patients had been randomly assigned, with 99 in the experimental group and 96 in the control group. All patients in the experimental group started treatment, as did 92 in the control group. Two patients in the control group received a molecularly targeted agent: both were included in their assigned group for efficacy analyses, the patient who received an agent that was allowed in the experimental group was included in the experimental group for the purposes of safety analyses, while the other patient, who received a molecularly targeted agent and chemotherapy, was kept in the control group for safety analyses. Median follow-up was 11·3 months (IQR 5·8–11·6) in the experimental group and 11·3 months (8·1–11·6) in the control group at the time of the primary analysis of progression-free survival. Median progression-free survival was 2·3 months (95% CI 1·7–3·8) in the experimental group versus 2·0 months (1·8–2·1) in the control group (hazard ratio 0·88, 95% CI 0·65–1·19, p=0·41). In the safety population, 43 (43%) of 100 patients treated with a molecularly targeted agent and 32 (35%) of 91 patients treated with cytotoxic chemotherapy had grade 3–4 adverse events (p=0·30). Interpretation The use of molecularly targeted agents outside their indications does not improve progression-free survival compared with treatment at physician's choice in heavily pretreated patients with cancer. Off-label use of molecularly targeted agents should be discouraged, but enrolment in clinical trials should be encouraged to assess predictive biomarkers of efficacy. Funding Institut Curie.
The diagnosis, histomolecular classes of breast cancers (luminal A, luminal B, HER2‐enriched, and basal‐like), and accurate prediction of prognosis are commonly determined using morphological and ...phenotypical analyses in clinical practice worldwide. Therapeutic strategies are mostly based on the disease stage and molecular subclasses of breast cancer. Targeted therapies, such as anti‐HER2s, poly‐ADP ribose polymerase inhibitors or, to a lesser extent, phosphatidylinositol 3 kinase inhibitors, have substantially improved breast cancer patient prognosis over the past decades. Human epidermal growth factor receptor 2 (HER2) overexpression is widely determined based on immunohistochemistry, while next‐generation sequencing (NGS) is currently employed to assess the presence of molecular alterations, including breast cancer gene 1 (BRCA1) and 2 or phosphatidylinositol‐4,5‐bisphosphate 3‐kinase catalytic subunit alpha (PIK3CA) mutations, which are targets of these new approved therapies. In addition, next‐generation sequencing (NGS) can aid the pathologist in challenging situations, such as a diagnostic workup for a metastatic carcinoma in lymph nodes of unknown origin, differential diagnosis of spindle cell tumourtumor in the breast between metaplastic carcinoma, malignant PT and sarcoma, o, as well as determining relatedness between primary breast cancers and recurrences. NGS offers a powerful tool that enables the pathologist to combine morphological analyses together with molecular alterations in challenging diagnostic situations.
Aims
High‐grade metaplastic breast carcinoma (HG‐MBC) is a rare subtype of invasive breast carcinoma, mostly triple‐negative. Metaplastic carcinomas are less responsive to neoadjuvant chemotherapy ...and are associated with a worse outcome than invasive carcinomas of no special type.
Methods
Clinicopathological characteristics and immunophenotype were retrospectively assessed in a series of 65 patients diagnosed with HG‐MBC between 2005 and 2017 at the Curie Institute (antibody panel: oestrogen receptor ER, progesterone receptor PR, androgen receptor AR, human epidermal growth factor receptor 2 HER2, programmed death ligand‐1 PD‐L1, and trophoblast cell surface antigen 2 TROP2).
Results
The median age at diagnosis was 59.5 years. Six (9%) patients had metastatic disease at diagnosis. Among the nonmetastatic patients receiving neoadjuvant therapy, 26% (5/19) achieved pathological complete response. Most tumours were pT1/pT2 (77%) and 12% were pN+. Histological subtypes (mixed, squamous, mesenchymal, and spindle cell) were 40%, 35.5%, 15.5%, and 9%, respectively. Tumour‐infiltrating lymphocytes were low or moderate except when squamous differentiation was present. Most tumours were triple‐negative (92%). AR and TROP2 were positive in 34% and 85% of the cases, respectively. PD‐L1 was positive in tumour cells in 18% (cutoff: 1% of positive tumour cells) of the cases and in tumour‐infiltrating immune cells in 40% (cutoff: 1% of tumour area) of the cases. Notably, spindle cell and mesenchymal metaplastic breast carcinomas were mostly PDL1‐negative. Lastly, 21 (32.3%) cases were HER2‐low, all being HER2 1+, with no HER2 2+.
Conclusion
Metaplastic breast carcinoma could benefit from tailored therapeutic strategies adapted to the phenotypic specificities of histological subtypes.
Representative immunostaining examples of androgen receptor (A & B), trophoblast cell surface antigen 2 (C & D), and programmed death ligand‐1 (E & F) expression in metaplastic breast carcinoma. Focal nuclear expression of androgen receptor in mesenchymal (A) and squamous (B) component of high‐grade metaplastic breast carcinoma (HG‐MBC). (C) Example of trophoblast cell surface antigen 2 (Trop2) cytoplasmic expression in a squamous component of HG‐MBC. (D) Strong, diffuse, and membranous staining of Trop2, in a squamous component. (E) Example of programmed death ligant‐1 (PD‐L1) expression in tumour cells: cytoplasmic heterogeneous staining of a squamous component. (F) Example of immune cells staining with PD‐L1‐antibody in a squamous component.
•Interobserver reproducibility for boost delineation in breast cancer is mostly poor.•The presence of clips and fluid in the surgical bed improves this reproducibility.•Pre-operative imaging is ...useful to improve the accuracy of tumour bed delineation.•Boost delineation has become even more challenging since oncoplastic surgery exists.•Guidelines involving surgeon, pathologist, radiologist and oncologist are essential.
Several randomized controlled trials have demonstrated the benefit of a boost to the tumor bed (TB) to reduce the risk of ipsilateral breast tumor recurrence. Recent technological progress has facilitated improved conformation of isodoses around the target volume. The accuracy and reproducibility of TB delineation have become even more essential. The purpose of this study is to review the extant knowledge on the boost delineation in breast cancer, focusing on interobserver variability (IOV) and the influence of various factors, such as the presence of clips or different imaging modalities to improve IOV. Most studies investigating IOV for boost delineation have shown poor reproducibility (with comparison indices such as the dice similarity index around 0.5). Clips in the lumpectomy cavity (LC), postoperative fluid accumulation in the LC and/or high cavity visualization score appeared to be associated with improved IOV. Likewise, the use of preoperative imaging (CT and/or MRI) may also be useful in improving the accuracy of TB definition but without any real gain in terms of IOV. Moreover, the delineation of boost has become even more challenging since the development of oncoplastic surgery. To improve the reproducibility and the accuracy of boost delineation, this review suggests that within each center, a group of multidisciplinary experts, including surgeons, radiation oncologists, pathologists, and radiologists, should convene to develop local guidelines, which may include the choice of preoperative imaging, the number and location of surgical clips, pathological margins, and orientation. The elaboration of contouring atlas is certainly of great assistance.
Anti‐cancer drugs often increase reactive oxygen species (ROS) and cause DNA damage. Here, we highlight a new cross talk between chronic oxidative stress and the histone variant H2AX, a key player in ...DNA repair. We observe that persistent accumulation of ROS, due to a deficient JunD‐/Nrf2‐antioxidant response, reduces H2AX protein levels. This effect is mediated by an enhanced interaction of H2AX with the E3 ubiquitin ligase RNF168, which is associated with H2AX poly‐ubiquitination and promotes its degradation by the proteasome. ROS‐mediated H2AX decrease plays a crucial role in chemosensitivity. Indeed, cycles of chemotherapy that sustainably increase ROS reduce H2AX protein levels in Triple‐Negative breast cancer (TNBC) patients. H2AX decrease by such treatment is associated with an impaired NRF2‐antioxidant response and is indicative of the therapeutic efficiency and survival of TNBC patients. Thus, our data describe a novel ROS‐mediated regulation of H2AX turnover, which provides new insights into genetic instability and treatment efficacy in TNBC patients.
Synopsis
This work gives new insights into the regulation of H2AX protein turnover under chronic oxidative stress that affects DNA damage response. H2AX degradation upon chronic stress sensitizes tumour cells to chemotherapy and is indicative of better survival in triple‐negative breast cancer patients.
Physiological conditions of chronic oxidative stress, mediated by the loss of JunD or Nrf2 transcription factors, are associated with a reduced protein level of the histone variant H2AX.
Under conditions of chronic stress due to junD or Nrf2 deficiency, H2AX protein is targeted for degradation by the proteasome.
ROS‐dependent H2AX degradation is mediated by enhanced interaction of H2AX protein with the E3 ubiquitin ligase RNF168.
H2AX decrease by chronic oxidative stress increases tumour cell genomic instability and death.
Chemosensitivity and survival of triple‐negative breast cancer patients are improved by stress‐mediated H2AX degradation following successive cycles of chemotherapy.
This work gives new insights into the regulation of H2AX protein turnover under chronic oxidative stress that affects DNA damage response. H2AX degradation upon chronic stress sensitizes tumour cells to chemotherapy and is indicative of better survival in triple‐negative breast cancer patients.
Although fibroblast heterogeneity is recognized in primary tumors, both its characterization in and its impact on metastases remain unknown. Here, combining flow cytometry, immunohistochemistry and ...RNA-sequencing on breast cancer samples, we identify four Cancer-Associated Fibroblast (CAF) subpopulations in metastatic lymph nodes (LN). Two myofibroblastic subsets, CAF-S1 and CAF-S4, accumulate in LN and correlate with cancer cell invasion. By developing functional assays on primary cultures, we demonstrate that these subsets promote metastasis through distinct functions. While CAF-S1 stimulate cancer cell migration and initiate an epithelial-to-mesenchymal transition through CXCL12 and TGFβ pathways, highly contractile CAF-S4 induce cancer cell invasion in 3-dimensions via NOTCH signaling. Patients with high levels of CAFs, particularly CAF-S4, in LN at diagnosis are prone to develop late distant metastases. Our findings suggest that CAF subset accumulation in LN is a prognostic marker, suggesting that CAF subsets could be examined in axillary LN at diagnosis.
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