Gene-expression assays to tailor adjuvant endocrine therapy for HR+/HER2- breast cancer.

Adjuvant endocrine therapy represents the standard of care for almost all HR+/HER2- breast cancers and different agents and durations are currently available. In this context, the tailoring and optimization of adjuvant endocrine treatment by reducing unnecessary toxic treatment while taking into account the biological heterogeneity of HR+/HER2- breast cancer represents a clinical priority. There is therefore a significant need for the integration of biological biomarkers in the choice of adjuvant endocrine therapy beyond currently used clinicopathological characteristics. Several gene-expression assays have been developed to identify patients with HR+/HER2- breast cancer who will not derive benefit from the addition of adjuvant chemotherapy. By enhancing risk stratification and predicting therapeutic response, genomic assays have also shown to be a promising tool for optimizing endocrine treatment decision. We here review evidence supporting the use of most common commercially available gene-expression assays (Oncotype DX, MammaPrint, Breast Cancer Index, Prosigna and EndoPredict) in tailoring adjuvant endocrine therapy. Available data on the use of genomic tests to inform extended adjuvant treatment choice based on the risk of late relapse and on the estimated benefit of a prolonged endocrine therapy are discussed. Moreover, preliminary evidence regarding the use of genomic assays to inform de-escalation of endocrine treatment, such as shorter durations or omission, for low risk patients are reviewed. Overall, gene expression assays are emerging as potential tools to further personalize adjuvant treatment for patients with HR+/HER2- breast cancers.

Characterization of Gut Microbiome Composition in Patients with Triple-Negative Breast Cancer Treated with Neoadjuvant Chemotherapy.

INTRODUCTION: Patients with triple-negative breast cancer (TNBC) achieving a pathological complete response (pCR) after neoadjuvant chemotherapy have a better event-free survival. The role of gut microbiome in early TNBC is underexplored. METHODS: Microbiome was analyzed by 16SrRNA sequencing. RESULTS: Twenty-five patients with TNBC treated with neoadjuvant anthracycline/taxane-based chemotherapy were included. Fifty-six percent achieved a pCR. Fecal samples were collected before (t0), at 1 (t1), and 8 weeks (t2) from chemotherapy. Overall, 68/75 samples (90.7%) were suitable for microbiome analysis. At t0, pCR group showed a significantly higher α-diversity as compared with no-pCR, (P = .049). The PERMANOVA test on ß-diversity highlighted a significant difference in terms of BMI (P = 0.039). Among patients with available matched samples at t0 and t1, no significant variation in microbiome composition was reported over time. CONCLUSIONS: Fecal microbiome analysis in early TNBC is feasible and deserves further investigation in order to unravel its complex correlation with immunity and cancer.

Prognostic impact of extracranial disease control in HER2+ breast cancer-related brain metastases.

BACKGROUND: Brain metastases (BM) are common among HER2+ breast cancer (BC) and prognostic stratification is crucial for optimal management. BC-GPA score and subsequent refinements (modified-GPA, updated-GPA) recapitulate prognostic factors. Since none of these indexes includes extracranial disease control, we evaluated its prognostic value in HER2+ BCBM. METHODS: Patients diagnosed with HER2+ BCBM at Istituto Oncologico Veneto-Padova (2002-2021) and Montpellier Cancer Institute (2001-2015) were included as exploratory and validation cohorts, respectively. Extracranial disease control at BM diagnosis (no disease/stable disease/response vs. progressive disease) was evaluated. RESULTS: In the exploratory cohort of 113 patients (median OS 12.2 months), extracranial control (n = 65, 57.5%) was significantly associated with better OS at univariate (median OS 17.7 vs. 8.7 months, p = 0.005) and multivariate analysis after adjustment for BC-GPA (HR 0.61, 95% CI 0.39-0.94), modified-GPA (HR 0.64, 95% CI 0.42-0.98) and updated-GPA (HR 0.63, 95% CI 0.41-0.98). The prognostic impact of extracranial disease control (n = 66, 56.4%) was then confirmed in the validation cohort (n = 117) at univariate (median OS 20.2 vs. 9.1 months, p < 0.001) and multivariate analysis adjusting for BC-GPA (HR 0.41, 95% CI 0.27-0.61), modified-GPA (HR 0.44, 95% CI 0.29-0.67) and updated-GPA (HR 0.42, 95% CI 0.28-0.63). CONCLUSIONS: Extracranial disease control provides independent prognostic information in HER2+ BCBM beyond commonly used prognostic scores.

Oligometastatic breast cancer: Dissecting the clinical and biological uniqueness of this emerging entity. Can we pursue curability?

Metastatic breast cancer represents an incurable condition, however, the increasing interest towards the oligometastatic entity is now challenging this assumption. Up to 20% of patients with metastatic breast cancer present with oligometastatic disease, which refers to metastatic breast cancer presenting or recurring with limited metastatic burden. In the last years, progressive advancements in imaging techniques, the growing availability of minimally invasive locoregional treatments, alongside the increasing expectations from a patient perspective, have contributed to rising the awareness towards this emerging entity. In the present work we comprehensively reviewed available evidence regarding oligometastatic breast cancer, focusing on clinical and biological notions virtually supporting the adoption of a curative approach when treating this condition. We also discussed main areas of uncertainties, providing a research agenda that may guide and fine-tune the future investigation in this field.

HER2-low-positive breast cancer: evolution from primary tumor to residual disease after neoadjuvant treatment.

Approximately a half of breast tumors classified as HER2-negative exhibit HER2-low-positive expression. We recently described a high instability of HER2-low-positive expression from primary breast cancer (BC) to relapse. Previous studies reporting discordance in HER2 status between baseline biopsy and residual disease (RD) in patients undergoing neoadjuvant treatment did not include the HER2-low-positive category. The aim of this study is to track the evolution of HER2-low-positive expression from primary BC to RD after neoadjuvant treatment. Patients undergoing neoadjuvant treatment with available baseline tumor tissue and matched samples of RD (in case of no pCR) were included. HER2-negative cases were sub-classified as HER2-0 or HER2-low-positive (IHC 1+ or 2+ and ISH negative). Four-hundred forty-six patients were included. Primary BC phenotype was: HR-positive/HER2-negative 23.5%, triple-negative (TN) 35%, HER2-positive 41.5%. HER2-low-positive cases were 55.6% of the HER2-negative cohort and were significantly enriched in the HR-positive/HER2-negative vs. TN subgroup (68.6% vs. 46.8%, p = 0.001 χ2 test). In all, 35.3% of non-pCR patients (n = 291) had a HER2-low-positive expression on RD. The overall rate of HER2 expression discordance was 26.4%, mostly driven by HER2-negative cases converting either from (14.8%) or to (8.9%) HER2-low-positive phenotype. Among HR-positive/HER2-negative patients with HER2-low-positive expression on RD, 32.0% and 57.1% had an estimated high risk of relapse according to the residual proliferative cancer burden and CPS-EG score, respectively. In conclusion, HER2-low-positive expression showed high instability from primary BC to RD after neoadjuvant treatment. HER2-low-positive expression on RD may guide personalized adjuvant treatment for high-risk patients in the context of clinical trials with novel anti-HER2 antibody-drug conjugates.

Neoadjuvant Chemotherapy and Immunotherapy in Luminal B-like Breast Cancer: Results of the Phase II GIADA Trial.

PURPOSE: The role of immunotherapy in hormone receptor (HR)-positive, HER2-negative breast cancer is underexplored. PATIENTS AND METHODS: The neoadjuvant phase II GIADA trial (NCT04659551, EUDRACT 2016-004665-10) enrolled stage II-IIIA premenopausal patients with Luminal B (LumB)-like breast cancer (HR-positive/HER2-negative, Ki67 ≥ 20%, and/or histologic grade 3). Patients received: three 21-day cycles of epirubicin/cyclophosphamide followed by eight 14-day cycles of nivolumab, triptorelin started concomitantly to chemotherapy, and exemestane started concomitantly to nivolumab. Primary endpoint was pathologic complete response (pCR; ypT0/is, ypN0). RESULTS: A pCR was achieved by 7/43 patients [16.3%; 95% confidence interval (CI), 7.4-34.9]; the rate of residual cancer burden class 0-I was 25.6%. pCR rate was significantly higher for patients with PAM50 Basal breast cancer (4/8, 50%) as compared with other subtypes (LumA 9.1%; LumB 8.3%; P = 0.017). Tumor-infiltrating lymphocytes (TIL), immune-related gene-expression signatures, and specific immune cell subpopulations by multiplex immunofluorescence were significantly associated with pCR. A combined score of Basal subtype and TILs had an AUC of 0.95 (95% CI, 0.89-1.00) for pCR prediction. According to multiplex immunofluorescence, a switch to a more immune-activated tumor microenvironment occurred following exposure to anthracyclines. Most common grade ≥3 treatment-related adverse events (AE) during nivolumab were γ-glutamyltransferase (16.7%), alanine aminotransferase (16.7%), and aspartate aminotransferase (9.5%) increase. Most common immune-related AEs were endocrinopathies (all grades 1-2; including adrenal insufficiency, n = 1). CONCLUSIONS: Luminal B-like breast cancers with a Basal molecular subtype and/or a state of immune activation may respond to sequential anthracyclines and anti-PD-1. Our data generate hypotheses that, if validated, could guide immunotherapy development in this context.

Gene-expression signatures to inform neoadjuvant treatment decision in HR+/HER2- breast cancer: Available evidence and clinical implications.

Over the last few years, the indication for chemotherapy use in HR+/HER2- early BC has been significantly modified by the introduction of gene-expression profiling. In the adjuvant setting, several gene-expression signatures have been validated to discriminate early stage HR+/HER2- BC with different prognosis and to identify patients for which adjuvant chemotherapy can be spared. Considering their ability to optimize the choice of adjuvant treatment and the increasing use of neoadjuvant approach in early BC, the potential use of gene-expression signatures to discriminate patients to be candidate to neoadjuvant chemotherapy or endocrine treatment appears particularly appealing. Indeed, the San Gallen Consensus Conference panel recently endorsed the use of genomic assays on core biopsies as a potential strategy for choosing the type of neoadjuvant treatment (chemotherapy or endocrine therapy) in selected patients. In this context, we here review evidence supporting the use of most common commercially available gene-expression signatures (Oncotype DX, MammaPrint, PAM50, EndoPredict and Breast Cancer Index) in patients receiving neoadjuvant therapy for HR+/HER2- BC. Data on the association of gene expression signatures and response to neoadjuvant chemotherapy or neoadjuvant endocrine therapy will be reviewed and the clinical implications of this data to guide the clinical decision-making process in early HR+/HER2- BC will be discussed.

Evolution of HER2-low expression from primary to recurrent breast cancer.

About a half of HER2-negative breast cancer (BC) show HER2-low expression that can be targeted by new antibody-drug conjugates. The main aim of this study is to describe the evolution of HER2 expression from primary BC to relapse by including HER2-low category in both primary and recurrent BC samples. Patients with matched primary and relapse BC samples were included. HER2 was evaluated according to ASCO/CAP recommendations in place at the time of diagnosis. A cutoff of >10% cells staining for HER2-positivity was applied. HER2-negative cases were sub-classified as HER2-low (IHC = 1 + /2+ and ISH not amplified), or HER2-0 (IHC-0). 547 patients were included. The proportion of HER2-low cases was 34.2% on the primary tumor and 37.3% on the relapse samples. Among HER2-negative cases, HER2-low status was more frequent in HR-positive vs triple-negative tumors (47.3% vs 35.4% on primary tumor samples, 53.8% vs 36.2% on relapse samples). The overall rate of HER2 discordance was 38.0%, mostly represented by HER2-0 switching to HER2-low (15%) and HER2-low switching to HER2-0 (14%). Among patients with a primary HER2-negative tumor, the rate of HER2 discordance was higher in HR-positive/HER2-negative vs triple-negative cases (45.5% vs 36.7% p = 0.170). This difference was mostly driven by cases switching from HER2-0 to HER2-low. HER2-low expression is highly unstable during disease evolution. Relapse biopsy in case of a primary HER2-0 tumor may open new therapeutic opportunities in a relevant proportion of patients.

Impact of estrogen receptor levels on outcome in non-metastatic triple negative breast cancer patients treated with neoadjuvant/adjuvant chemotherapy.

Although 1% is the recommended cut-off to define estrogen receptor (ER) positivity, a 10% cut-off is often used in clinical practice for therapeutic purposes. We here evaluate clinical outcomes according to ER levels in a monoinstitutional cohort of non-metastatic triple-negative breast cancer (BC) patients undergoing (neo)adjuvant chemotherapy. Clinicopathological data of 406 patients with ER < 10% HER2-negative BC treated with (neo)adjuvant chemotherapy between 01/2000 and 04/2019 were collected. Patients were categorized in ER-negative (ER < 1%; N = 364) and ER-low positive (1-9%, N = 42). At a median follow-up of 54 months, 88 patients had relapsed and 64 died. No significant difference was observed in invasive relapse-free survival (iRFS) and overall survival (OS) according to ER expression levels, both at univariate and multivariate analysis (5-years iRFS 74.0% versus 73.1% for ER-negative and ER-low positive BC, respectively, p = 0.6; 5-years OS 82.3% versus 76.7% for ER-negative and ER-low positive BC, respectively, p = 0.8). Among the 165 patients that received neoadjuvant chemotherapy, pathological complete response rate was similar in the two cohorts (38% in ER-negative, 44% in ER-low positive, p = 0.498). In conclusion, primary BC with ER1-9% shows similar clinical behavior to ER 1% BC. Our results suggest the use of a 10% cut-off, rather than <1%, to define triple-negative BC.

Postsurgical Pyoderma Gangrenosum in a Breast Cancer Patient: A Case Report and Literature Review.

Pyoderma gangrenosum is a rare skin necrotizing disease that can arise on a site of surgical trauma. Its pathogenesis has recently been related to dysregulation of the immune system, with inflammatory bowel disease representing the most commonly underlying systemic conditions. Several authors have also reported an association with solid malignancies (especially gastrointestinal and breast cancer). We describe the case of a 39-year-old patient diagnosed with a locally advanced, triple-negative breast cancer who developed a pyoderma gangrenosum on the surgical wound after a CVC implant with systemic complications. As the diagnosis and management of postsurgical pyoderma gangrenosum can be challenging for clinicians, underlying conditions as autoimmune disease and solid tumors have to be considered in order to guide treatment.

ESR1 Gene Mutation in Hormone Receptor-Positive HER2-Negative Metastatic Breast Cancer Patients: Concordance Between Tumor Tissue and Circulating Tumor DNA Analysis.

Endocrine therapy represents the cornerstone of treatment in hormone receptor-positive (HR+), HER2-negative metastatic breast cancer (mBC). The natural course of this disease is marked by endocrine resistance, mainly due to Estrogen Receptor 1 (ESR1) acquired mutations. The aim of this study is to evaluate the concordance between ESR1 status in metastatic tumor specimens and matched circulating tumor DNA (ctDNA). Forty-three patients with HR+, HER2-negative mBC underwent both a metastatic tumor biopsy and a liquid biopsy at the time of disease progression. DNA extracted from formalin fixed paraffin embedded (FFPE) tumor specimens and ctDNA from matched plasma were analyzed by droplet digital (dd)PCR for the main ESR1 mutations (Y537S, Y537C, Y537N, D538G, E380Q). We observed a total mutation rate of 21%. We found six mutations on tissue biopsy: Y537S (1), D538G (2), Y537N (1), E380Q (2). Three patients with no mutations in tumor tissue had mutations detected in ctDNA. The total concordance rate between ESR1 status on tumor tissue and plasma was 91%. Our results confirm the potential role of liquid biopsy as a non-invasive alternative to tissue biopsy for ESR1 mutation assessment in mBC patients.

Validation of Residual Proliferative Cancer Burden as a Predictor of Long-Term Outcome Following Neoadjuvant Chemotherapy in Patients with Hormone Receptor-Positive/Human Epidermal Growth Receptor 2-Negative Breast Cancer.

BACKGROUND: The integration of residual cancer burden (RCB) and post-treatment Ki67 as residual proliferative cancer burden (RPCB) has been proposed as a stronger predictor of long-term outcome in unselected patients with breast cancer (BC) undergoing neoadjuvant chemotherapy (NACT), as compared with RCB. However, no specific analysis in hormone-receptor-positive (HR+) human epidermal growth receptor 2-negative (HER2-) BC is available so far. MATERIALS AND METHODS: A cohort of 130 patients with HR+/HER2- BC who underwent NACT between 2000 and 2014 was included. Archival surgical specimens were evaluated for RCB. RPCB was calculated by combining RCB and Ki67 as previously described. Patients were categorized in four RCB and RPCB categories (pathological complete response and tertiles). Disease-free survival (DFS) and overall survival (OS) estimates were determined by Kaplan-Meier analysis and compared using the log-rank test. Overall change of χ2 and c-indexes were used to compare the performance of the prognostic models. RESULTS: RPCB was calculated for 85 patients. After a median follow up of 8.5 years, RCB was associated with OS (p = .048) but not with DFS (p = .152); RPCB was instead significantly associated with both DFS and OS (p = .034 and p < .001, respectively). In terms of OS, RPCB provided a significant amount of prognostic information beyond RCB (∆χ2 5.73, p < .001). In addition, c-index for OS prediction was significantly higher for RPCB as compared with RCB (0.79 vs. 0.61, p = .03). CONCLUSION: This is the first study evaluating RPCB in patients with HR+/HER2- BC treated with NACT. In this independent cohort, RPCB was a strong predictor of DFS and OS. The better performance of RPCB versus RCB was in part due to the ability of RPCB to discriminate a subgroup of patients with a particularly worse prognosis after NACT, who may be candidates for clinical trials evaluating novel adjuvant strategies. IMPLICATIONS FOR PRACTICE: The present work validated residual proliferative cancer burden (RPCB) as a strong predictor of long-term outcome in patients with hormone receptor-positive human epidermal growth receptor 2-negative (HR+/HER2-) breast cancer (BC) treated with neoadjuvant chemotherapy. In addition, results from the present study suggest RPCB as a promising tool to identify patients with HR+/HER2- BC who might potentially benefit from the inclusion in clinical trials evaluating novel or escalated postneoadjuvant treatment strategies because it allowed to discriminate a subgroup of patients with particularly poor prognosis despite having received subsequent endocrine therapy in the adjuvant setting.

Use of scalp cooling device to prevent alopecia for early breast cancer patients receiving chemotherapy: A prospective study.

Chemotherapy-induced alopecia (CIA) affects the majority of patients receiving chemotherapy (CT) for early breast cancer. It is a highly distressing side effect of CT, with psychological and social impact. Primary aim of the present analysis was to assess the efficacy of scalp cooling with DigniCap® in preventing CIA. Success rate was defined as patients' self-reported hair loss <50% according to Dean scale. In this analysis, we reported success rate at 3 weeks after the first CT course and at 3 weeks after the last CT course. Secondary endpoints included self-reported tolerability and patients' judgment on scalp cooling performance. Consecutive early breast cancer patients admitted to Istituto Oncologico Veneto who were recommended to receive neoadjuvant or adjuvant CT, were eligible to undergo scalp cooling during the CT administration within this study. 135 patients were included: 74% received adjuvant CT and 26% neoadjuvant CT (P < .001). The type of CT was: docetaxel-cyclophosphamide (26%), paclitaxel (23%), epirubicin-cyclophosphamide followed by paclitaxel (32%), and paclitaxel followed by epirubicincyclophosphamide (19%). The rate of success in preventing alopecia was 77% (104/135) at 3 weeks from the start of CT and 60% (81/135) at 3 weeks from the end of treatment. Higher success rates were reported in non-anthracycline (71%) compared to anthracycline-containing CT regimens (54%; P < 0.001). Premature discontinuation of scalp cooling was reported in 29/135 patients (21.5%), including withdrawal for alopecia (16/29), for low scalp cooling tolerability (8/29) or both (5/29). Scalp cooling was generally well tolerated. These results overall suggest that the use of scalp cooling is effective in preventing alopecia in the majority of early breast cancer patients receiving neoadjuvant or adjuvant CT, especially for patients undergoing a taxane-based non-anthracycline regimen.

Androgen Receptor Expression and Association With Distant Disease-Free Survival in Triple Negative Breast Cancer: Analysis of 263 Patients Treated With Standard Therapy for Stage I-III Disease.

Background: We evaluated immunohistochemical AR expression and correlation with prognosis in a large series of homogeneously treated patients with primary TNBC. Material and Methods: Patients diagnosed with stage I-III TNBC between 2000 and 2015 at Istituto Oncologico Veneto who received treatment with surgery and neoadjuvant and/or adjuvant chemotherapy were included. Whole tissue slides were stained for AR. AR-positive expression was defined as >1% of positively stained tumor cells. Distant-disease-free survival (DDFS) was calculated from diagnosis to distant relapse or death. Late-DDFS was calculated from the landmark of 3 years after diagnosis until distant relapse or death. Results: We included 263 primary TNBC patients. Mean AR expression was 14% (range 0-100%), and 29.7% (n = 78) of patients were AR+. AR+ vs. AR- cases presented more frequently older age (p < 0.001), non-ductal histology (p < 0.001), G1-G2 (p = 0.003), lower Ki67 (p < 0.001) and lower TILs (p = 0.008). At a median follow up of 81 months, 23.6% of patients experienced a DDFS event: 33.3% of AR+ and 19.5% of AR- patients (p = 0.015). 5 years DDFS rates were 67.2% and 80.6% for AR+ and AR- patients (HR = 1.82 95%CI 1.10-3.02, p = 0.020). AR maintained an independent prognostic role beyond stage, but when TILs were added to the model only stage and TILs were independent prognostic factors. AR was the only factor significantly associated with late-DDFS: 16.4% of AR+ and 3.4% of AR- patients experienced a DDFS after the landmark of 3 years after diagnosis (p = 0.001). Late-DDFS rates at 5 years from the 3-year landmark were 75.8% for AR+ and 95.2% for AR- patients (log-rank p < 0.001; HR = 5.67, 95%CI 1.90-16.94, p = 0.002). Conclusions: AR expression is associated with worse outcome for patients with TNBC. In particular, AR+ TNBC patients are at increased risk of late DDFS events. These results reinforce the rationale of AR targeting in AR+ TNBC.

Patterns of Fertility Preservation and Pregnancy Outcome After Breast Cancer at a Large Comprehensive Cancer Center.

BACKGROUND: In the last decades, long-term outcomes of breast cancer (BC) patients have improved, raising new survivorship issues, including fertility preservation and safety of pregnancy after BC. This study assesses evolution in patterns of fertility discussion/preservation over time and reports pregnancy outcomes in a cohort of young BC patients. METHODS: A retrospective cohort of 590 BC patients aged ≤40 diagnosed between 2000 and 2016 at a large cancer center was identified. Fertility counseling and preservation patterns for patients receiving chemotherapy were analyzed and compared for two cohorts: 2004-2006 and 2014-2016 (total n = 161). Outcomes were reported for patients with documented pregnancy after BC. RESULTS: Significantly, more patients diagnosed in 2014-2016 had evidence of discussion on fertility issues and/or application of fertility preservation techniques versus patients diagnosed in 2004-2006 (82.9% vs. 66.0%, p = 0.017). In particular, there was a significant difference in rate of documented fertility issues discussion (67.6% vs. 34.0%, p < 0.001). Age >35 and parity were associated with lower rates of fertility discussion/preservation. However, rates significantly improved over time (77.6% in 2014-2016 vs. 58.1% in 2004-2006 for patients aged >35, p = 0.046; 80.7% in 2014-2016 vs. 57.6% in 2004-2006 for patients with children at diagnosis, p = 0.018). Twenty-six patients with pregnancy after BC were identified; eight delivered at the age of >40. No complications for women or newborns were reported. Only two patients experienced BC relapse. CONCLUSIONS: In this small retrospective cohort, no safety concerns were identified for pregnancy after BC. The importance attributed by clinicians to address fertility issues has increased over time.

Escalation and de-escalation in HER2 positive early breast cancer.

PURPOSE OF REVIEW: Current standard for HER2+ early breast cancer patients includes chemotherapy and trastuzumab for 1 year. The purpose of this article is to review available evidence on escalated treatment strategies for high-risk patients and de-escalated treatments for patients at low risk of relapse or high risk of cardiac toxicity. RECENT FINDINGS: Recent results have led to the approval of two adjuvant escalated treatment strategies: pertuzumab and trastuzumab combined with chemotherapy for up to 1 year for high-risk patients; extension of adjuvant anti-HER2 treatment with 1 year of neratinib. However, these treatments are associated with increased costs and toxicity, therefore careful patients' selection is highly required. With regard to de-escalated treatments, the anthracycline-free regimen of adjuvant paclitaxel and 1 year trastuzumab has entered clinical practice for early-stage patients. One year of trastuzumab remains the standard; however, shorter trastuzumab could be an option for low-risk patients and in case of increased risk of cardiotoxocity. Chemotherapy-free regimens are attractive but deserve further evaluation. SUMMARY: There have been advances in treatment individualization for HER2+ early breast cancer patients. Integration of promising biomarkers into risk classification will further help progressing in the field.

Immune characterization of breast cancer metastases: prognostic implications.

BACKGROUND: Tumor-infiltrating lymphocytes (TILs) evaluated in primary breast cancer (BC) convey prognostic information. Limited data in the metastatic setting are available. METHODS: Secondary lesions from 94 BC patients, 43 triple-negative (TN) and 51 HER2-positive, were evaluated for TILs and expression of CD8, FOXP3, and PD-L1 by immunohistochemistry. RESULTS: TILs levels on metastasis were generally low (median 5%) and did not differ between TN and HER2+ tumors. Younger patients showed significantly lower TILs (p = 0.002). In HER2+ patients, TILs were higher in lung metastases as compared to other sites (p = 0.038). TILs composition was different across metastatic sites: skin metastases presented higher FOXP3 (p = 0.002) and lower CD8/FOXP3 ratio (p = 0.032). Patients treated for metastatic BC prior to biopsy had lower CD8 (overall: p = 0.005, HER2+: p = 0.011, TN: p = 0.075). In TN patients, median overall survival (OS) was 11.8 and 62.9 months for patients with low and high TILs, respectively (HR 0.29, 95%CI 0.11-0.76, log-rank p = 0.008). CD8/FOXP3 ratio was also prognostic in TN patients (median OS 8.0, 13.2, and 54.0 months in 1st, 2nd and 3th tertile, log-rank p = 0.019). Both TILs and CD8/FOXP3 ratio were independent factors at multivariate analysis. Counterintuitively, in HER2+ BC, low TILs tumors showed better prognosis (median OS 53.7 vs 39.9 months in TILs low and TILs high, not statistically significant). CONCLUSIONS: Our findings indicate the relevance of TILs as prognostic biomarker for TNBC even in the advanced setting and provide novel hypothesis-generating data on potential sources of immune heterogeneity of metastatic BC.