The clinical relevance of the host immune system in breast cancer has long been unexplored. Studies developed over the past decade have highlighted the biological heterogeneity of breast cancer, ...prompting researchers to investigate whether the role of the immune system in this malignancy is similar across different molecular subtypes of the disease. The presence of high levels of lymphocytic infiltration has been consistently associated with a more-favourable prognosis in patients with early stage triple-negative and HER2-positive breast cancer. These infiltrates seem to reflect favourable host antitumour immune responses, suggesting that immune activation is important for improving survival outcomes. In this Review, we discuss the composition of the immune infiltrates observed in breast cancers, as well as data supporting the clinical relevance of host antitumour immunity, as represented by lymphocytic infiltration, and how this biomarker could be used in the clinical setting. We also discuss the rationale for enhancing immunity in breast cancer, including early data on the efficacy of T-cell checkpoint inhibition in this setting.
Summary Background High quantities of tumour-infiltrating lymphocytes (TILs) in primary HER2-positive breast cancer are associated with improved prognosis and response to therapy. We aimed to ...investigate the prognostic role of host antitumour immunity as represented by baseline quantities of TILs in patients with advanced HER2-positive breast cancer treated with either pertuzumab or placebo in addition to trastuzumab and docetaxel. Methods CLEOPATRA was a randomised phase 3 study comparing the addition of either pertuzumab or placebo to first-line therapy with trastuzumab and docetaxel for patients with locally recurrent, unresectable, or metastatic HER2-positive breast cancer. We assessed the quantity of stromal TILs in prospectively collected tumour samples and investigated their association with progression-free survival, overall survival, clinicopathological characteristics, and pertuzumab treatment. We estimated hazard ratios (HR) and 95% CIs with multivariate Cox regression models fitting stromal TILs as a continuous variable (per 10% increment). The CLEOPATRA trial is registered with ClinicalTrials.gov , number NCT00567190. Findings Tumour samples from 678 (84%) of 808 participants were evaluable for TILs, including 519 (77%) archival samples, 155 (23%) freshly obtained samples (collected 45 days or fewer before randomisation), and four samples of unknown archival status. Median follow-up was 50 months (IQR 41–54) for progression-free survival and 51 months (IQR 46–57) for overall survival. 519 progression-free survival events occurred and 358 patients died. The median TIL value was 10% (IQR 5–30). Freshly obtained tumour samples had significantly lower TIL values than did archival samples (10·00% 95% CI 5·00–20·00 vs 15·00% 5·00–35·00; p=0·00036). We detected no significant association between TIL values and progression-free survival (adjusted HR 0·95, 95% CI 0·90–1·00, p=0·063). However, for overall survival, each 10% increase in stromal TILs was significantly associated with longer overall survival (adjusted HR 0·89, 95% CI 0·83–0·96, p=0·0014). The treatment effect of pertuzumab did not differ significantly by stromal TIL value for either progression-free survival (pinteraction =0·23) or overall survival (pinteraction =0·21). Interpretation In patients with advanced HER2-positive breast cancer treated with docetaxel, trastuzumab, and pertuzumab or placebo, higher TIL values are significantly associated with improved overall survival, suggesting that the effect of antitumour immunity extends to the advanced setting. Future clinical studies in this cancer subtype should consider TILs as a stratification factor and investigate whether therapies that can augment immunity could potentially further improve survival. Funding F Hoffmann-La Roche–Genentech and the Breast Cancer Research Foundation.
While breast cancer has not been considered a cancer amenable to immunotherapeutic approaches, recent studies have demonstrated evidence of significant immune cell infiltration via tumor-infiltrating ...lymphocytes in a subset of patient tumors. In this review we present the current evidence highlighting the clinical relevance and utility of tumor-infiltrating lymphocytes in breast cancer. Retrospective and prospective studies have shown that the presence of tumor-infiltrating lymphocytes is a prognostic marker for higher responses to neoadjuvant chemotherapy and better survival, particularly in triple negative and HER2-positive early breast cancer. Further work is required to determine the immune subsets important in this response and to discover ways of encouraging immune infiltrate in tumor-infiltrating lymphocytes-negative patients.
Stereotactic ablative body radiotherapy (SABR) is an emerging noninvasive approach for the treatment of oligometastases. Limited prospective evidence is available in breast cancer.
To determine the ...safety and feasibility of single fraction SABR for patients with bone only oligometastatic breast cancer. Secondary endpoints were local and distant progression-free survival (LPFS and DPFS), toxicity and response assessment.
In this single institution prospective trial we screened patients with computed tomography, bone scan, and sodium fluoride positron emission tomography. Eligible patients had one to three bone only oligometastases. All patients were treated at a dose of 20Gy in 1 fraction to each metastasis. Kaplan-Meier methods were used to determine local and distant progression free survival (LPFS and DPFS). Toxicity was graded using Common Terminology Criteria for Adverse Event version 4.0.
15 eligible patients were recruited to the study. Median follow-up time was 24 months. The treatment was feasible in 12 (80%) of patients with 3 (20%) of patients having treatment delayed by more than 3 days. 10 (67%) of patients experienced grade 1 treatment related toxicity, 4 (27%) experienced grade 2 toxicity and no patients experienced grade 3 or 4 treatment related toxicity. The two-year LPFS was 100%, DPFS was 67%.
We observed that SABR is feasible, well tolerated and effective in this cohort with two thirds of patients disease-free at two years. In selected patients with bone-only oligometastatic disease, SABR could be considered a treatment option. Randomised trials are required to assess the impact of SABR on overall survival when compared to the standard of care.
•Stereotactic ablative body radiotherapy is safe and feasible in oligometastatic breast cancer.•A single fraction is a convenient for patients.•Local control is 100% at 2 years.•Progression free survival is promising in luminal breast cancer patients.
The interest in tumor-infiltrating lymphocytes (TILs) as a prognostic biomarker in breast cancer has grown in recent years. Biomarkers must undergo comprehensive evaluation in terms of analytical ...validity, clinical validity and clinical utility before they can be accepted as part of clinical practice. The International Immuno-Oncology Biomarker Working Group has developed a practice guideline on scoring TILs in breast cancer in order to standardize TIL assessment. The prognostic value of TILs as a biomarker in early-stage breast cancer has been established by assessing tumor samples in thousands of patients from large prospective clinical trials of adjuvant therapy. There is a strong linear relationship between increase in TILs and improved disease-free survival for triple-negative and HER2-positive disease. Higher levels of TILs have also been associated with increased rates of pathological complete response to neoadjuvant therapy. TILs have potential clinical utility in breast cancer in a number of areas. These include prediction of responders to immune checkpoint blockade, identification of primary HER2-positive and triple-negative patients who have excellent prognoses and may thus be appropriate for treatment de-escalation, and potentially incorporation into a neoadjuvant endpoint which may be a better surrogate maker for drug development.
Understanding the cancer genome is seen as a key step in improving outcomes for cancer patients. Genomic assays are emerging as a possible avenue to personalised medicine in breast cancer. However, ...evolution of the cancer genome during the natural history of breast cancer is largely unknown, as is the profile of disease at death. We sought to study in detail these aspects of advanced breast cancers that have resulted in lethal disease.
Three patients with oestrogen-receptor (ER)-positive, human epidermal growth factor receptor 2 (HER2)-negative breast cancer and one patient with triple negative breast cancer underwent rapid autopsy as part of an institutional prospective community-based rapid autopsy program (CASCADE). Cases represented a range of management problems in breast cancer, including late relapse after early stage disease, de novo metastatic disease, discordant disease response, and disease refractory to treatment. Between 5 and 12 metastatic sites were collected at autopsy together with available primary tumours and longitudinal metastatic biopsies taken during life. Samples underwent paired tumour-normal whole exome sequencing and single nucleotide polymorphism (SNP) arrays. Subclonal architectures were inferred by jointly analysing all samples from each patient. Mutations were validated using high depth amplicon sequencing. Between cases, there were significant differences in mutational burden, driver mutations, mutational processes, and copy number variation. Within each case, we found dramatic heterogeneity in subclonal structure from primary to metastatic disease and between metastatic sites, such that no single lesion captured the breadth of disease. Metastatic cross-seeding was found in each case, and treatment drove subclonal diversification. Subclones displayed parallel evolution of treatment resistance in some cases and apparent augmentation of key oncogenic drivers as an alternative resistance mechanism. We also observed the role of mutational processes in subclonal evolution. Limitations of this study include the potential for bias introduced by joint analysis of formalin-fixed archival specimens with fresh specimens and the difficulties in resolving subclones with whole exome sequencing. Other alterations that could define subclones such as structural variants or epigenetic modifications were not assessed.
This study highlights various mechanisms that shape the genome of metastatic breast cancer and the value of studying advanced disease in detail. Treatment drives significant genomic heterogeneity in breast cancers which has implications for disease monitoring and treatment selection in the personalised medicine paradigm.
The presence of tumor-infiltrating lymphocytes in triple-negative breast cancers is correlated with improved outcomes. Ras/MAPK pathway activation is associated with significantly lower levels of ...tumor-infiltrating lymphocytes in triple-negative breast cancers and while MEK inhibition can promote recruitment of tumor-infiltrating lymphocytes to the tumor, here we show that MEK inhibition adversely affects early onset T-cell effector function. We show that α-4-1BB and α-OX-40 T-cell agonist antibodies can rescue the adverse effects of MEK inhibition on T cells in both mouse and human T cells, which results in augmented anti-tumor effects in vivo. This effect is dependent upon increased downstream p38/JNK pathway activation. Taken together, our data suggest that although Ras/MAPK pathway inhibition can increase tumor immunogenicity, the negative impact on T-cell activity is functionally important. This undesirable impact is effectively prevented by combination with T-cell immune agonist immunotherapies resulting in superior therapeutic efficacy.MEK inhibition in breast cancer is associated with increased tumour infiltrating lymphocytes (TILs), however, MAPK activity is required for T cells function. Here the authors show that TILs activity following MEK inhibition can be enhanced by agonist immunotherapy resulting in synergic therapeutic effects.
PD-1 axis blockade, in combination with chemotherapy, improves outcomes in advanced triple-negative breast cancer that is PD-L1 positive. The phase 3 KEYNOTE-522 trial now shows that the addition of ...pembrolizumab to chemotherapy improves pathological complete response rates regardless of PD-L1 status and appears to improve survival.
PD-1 axis blockade, in combination with chemotherapy, improves outcomes in advanced triple-negative breast cancer that is PD-L1 positive. The phase 3 KEYNOTE-522 trial now shows that the addition of pembrolizumab to chemotherapy improves pathological complete response rates regardless of PD-L1 status and appears to improve survival.
Metastatic breast cancer remains incurable. Next-generation sequencing (NGS) offers the ability to identify actionable genomic alterations in tumours which may then be matched with targeted ...therapies, but the implementation and utility of this approach is not well defined for patients with metastatic breast cancer.
We recruited patients with advanced breast cancer of any subtype for prospective targeted NGS of their most recent tumour samples, using a panel of 108 breast cancer-specific genes. Genes were classified as actionable or non-actionable using the European Society of Medical Oncology Scale for Clinical Actionability of Molecular Targets (ESCAT) guidelines.
Between February 2014 and May 2019, 322 patients were enrolled onto the study, with 72% (n = 234) of patients successfully sequenced (n = 357 samples). The majority (74%, n = 171) of sequenced patients were found to carry a potentially actionable alteration, the most common being a PIK3CA mutation. Forty-three percent (n = 74) of patients with actionable alterations were referred for a clinical trial or referred for confirmatory germline testing or had a change in therapy outside of clinical trials. We found alterations in AKT1, BRCA2, CHEK2, ESR1, FGFR1, KMT2C, NCOR1, PIK3CA and TSC2 to be significantly enriched in our metastatic population compared with primary breast cancers. Concordance between primary and metastatic samples for key driver genes (TP53, ERBB2 amplification) was > 75%. Additionally, we found that patients with a higher number of mutations had a significantly worse overall survival.
Genomic profiling of patients with metastatic breast cancer can have clinical implications and should be considered in all suitable patients.
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