Breast cancer (BC) is a complex disease with primary or acquired incurability characteristics in a significant part of patients. Immunotherapeutical agents represent an emerging option for breast cancer treatment, including the human epidermal growth factor 2 positive (HER2+) subtype. The immune system holds the ability to spontaneously implement a defensive response against HER2+ BC cells through complex mechanisms which can be exploited to modulate this response for obtaining a clinical benefit. Initial immune system modulating strategies consisted mostly in vaccine therapies, which are still being investigated and improved. However, the entrance of trastuzumab into the scenery of HER2+ BC treatment was the real game changing event, which embodied a dominant immune-mediated mechanism. More recently, the advent of the immune checkpoint inhibitors has caused a new paradigm shift for immuno-oncology, with promising initial results also for HER2+ BC. Breast cancer has been traditionally considered poorly immunogenic, being characterized by relatively low tumor mutation burden (TMB). Nevertheless, recent evidence has revealed high tumor infiltrating lymphocytes (TILs) and programmed cell death-ligand 1 (PD-L1) expression in a considerable proportion of HER2+ BC patients. This may translate into a higher potential to elicit anti-cancer response and, therefore, wider possibilities for the use and implementation of immunotherapy in this subset of BC patients. We are herein presenting and critically discussing the most representative evidence concerning immunotherapy in HER2+ BC cancer, both singularly and in combination with therapeutic agents acting throughout HER2-block, immune checkpoint inhibition and anti-cancer vaccines. The reader will be also provided with hints concerning potential future projection of the most promising immutherapeutic agents and approaches for the disease of interest.

Introduction: Molecular characterization studies revealed recurrent kelch like ECH associated protein 1 gene (KEAP1)/nuclear factor, erythroid 2 like 2 gene (NFE2L2) alterations in NSCLC. These genes encode two interacting proteins (a stress response pathway [SRP]) that mediate a cytoprotective response to oxidative stress and xenobiotics. Nevertheless, whether KEAP1/NFE2L2 mutations have an impact on clinical outcomes is unclear. Methods: We performed amplicon-based next-generation sequencing to characterize the SRP in patients with metastatic NSCLC (Regina Elena National Cancer Institute cohort [n ¼ 88]) treated with first-line chemotherapy. Mutations in the DNA damage response (tumor protein p53 gene [TP53], ATM serine/threonine kinase gene [ATM], and ATR serine/threonine kinase gene [ATR]) were concomitantly analyzed. In lung adenocarcinoma (LAC), we also determined the expression of phosphorylated ataxia telangiectasia mutated kinase and ataxia telangiectasia and Rad3-related protein. Two independent cohorts (the Memorial Sloan Kettering Cancer Center cohort and The Cancer Genome Atlas cohort) with data from approximately 1400 patients with advanced LAC were used to assess the reproducibility of the results.Results: In the Regina Elena National Cancer Institute cohort, patients whose tumors carried mutations in the KEAP1/NFE2L2 pathway had significantly shorter progression-free survival and overall survival than their wild-type counterparts did (log-rank p ¼ 0.006 and p ¼ 0.018, respectively). This association was driven by LAC in which KEAP1/NFE2L2 mutations were overrepresented in

Triple negative tumors represent 15% of breast cancer and are characterized by the lack of estrogen receptors, progesterone receptor, and HER2 amplification or overexpression. Approximately 25% of patients diagnosed with triple negative breast cancer carry a germline BRCA1 or BRCA2 mutation. They have an aggressive biology, and chemotherapy has been the mainstay of treatment for a long time. Despite intensive therapies, prognosis is still poor, and many patients will eventually relapse or die due to cancer. Therefore, novel targeted agents that can increase the treatment options for this disease are urgently needed. Recently, a new class of molecules has emerged as a standard of care for patients with triple negative breast cancer and germline BRCA1 or BRCA2 mutation: poly (ADP-ribose) (PARP) inhibitors. In the first part of the review, we summarize and discuss evidence supporting the use of PARP inhibitors. Currently, two PARP inhibitors have been approved for triple negative metastatic breast cancer—olaparib and talazoparib—based on two phase III trials, which showed a progression-free survival benefit when compared to chemotherapy. Safety profile was manageable with supportive therapies and dose reductions/interruptions. In addition, other PARP inhibitors are currently under investigation, such as talazoparib, rucaparib, and veliparib. Subsequently, we will discuss the potential role of PARP inhibitors in the future. Clinical research areas are investigating PARP inhibitors in combination with other agents and are including patients without germline BRCA mutations: ongoing phase II/III studies are combining PARP inhibitors with immunotherapy, while phases I and II trials are combining PARP inhibitors with other targeted agents such as ATM and PIK3CA inhibitors. Moreover, several clinical trials are enrolling patients with somatic BRCA mutation or patients carrying mutations in genes, other than BRCA1/2, involved in the homologous recombination repair pathway (e.g., CHECK2, PALB2, RAD51, etc.).

Background HER2-targeting agents have dramatically changed the therapeutic landscape of HER2+ advanced breast cancer (ABC). Within a short time frame, the rapid introduction of new therapeutics has led to the approval of pertuzumab combined with trastuzumab and a taxane in first-line, and trastuzumab emtansine (T-DM1) in second-line. Thereby, evidence of T-DM1 efficacy following trastuzumab/pertuzumab combination is limited, with data from some retrospective reports suggesting lower activity. The purpose of the present study is to investigate T-DM1 efficacy in pertuzumab-pretreated and pertuzumab naïve HER2 positive ABC patients. We also aimed to provide evidence on the exposure to different drugs sequences including pertuzumab and T-DM1 in HER2 positive cell lines. Methods The biology of HER2 was investigated in vitro through sequential exposure of resistant HER2 + breast cancer cell lines to trastuzumab, pertuzumab, and their combination. In vitro experiments were paralleled by the analysis of data from 555 HER2 + ABC patients treated with T-DM1 and evaluation of T-DM1 efficacy in the 371 patients who received it in second line. Survival estimates were graphically displayed in Kaplan Meier curves, compared by log rank test and, when possibile, confirmed in multivariate models. Results We herein show evidence of lower activity of T-DM1 in two HER2+ breast cancer cell lines resistant to trastuzumab+pertuzumab, as compared to trastuzumab-resistant cells. Lower T-DM1 efficacy was associated with a marked reduction of HER2 expression on the cell membrane and its nuclear translocation. HER2 downregulation at the membrane level was confirmed in biopsies of four trastuzumab/pertuzumab-pretreated patients. Among the 371 patients treated with second-line T-DM1, median overall survival (mOS) from diagnosis of advanced disease and median progression-free survival to second-line treatment (mPFS2) were 52 and 6 months in 177 patients who received trastuzumab/pertuzumab in first-line, and 74 and 10 months in 194 pertuzumab-naïve patients (p = 0.0006 and 0.03 for OS and PFS2, respectively). Conclusions Our data support the hypothesis that the addition of pertuzumab to trastuzumab reduces the amount of available plasma membrane HER2 receptor, limiting the binding of T-DM1 in cancer cells. This may help interpret the less favorable outcomes of second-line T-DM1 in trastuzumab/pertuzumab pre-treated patients compared to their pertuzumab-naïve counterpart.

Body mass index (BMI) is a main indicator of obesity and its association with breast cancer is well established. However, little is known in the metastatic setting, especially in HER2‐positive patients. We assessed the influence of BMI on clinical outcomes of patients treated with pertuzumab and/or trastuzumab emtansine (T‐DM1) for HER2+ metastatic breast cancer (mBC). BMI was addressed as a categorical variable, being classified on the basis of the following ranges, that is, 18.5–24.9, 25–29.9, and 30.0–34.9, namely, normal weight, overweight, and Class I obesity. The outcomes chosen were progression‐free survival to first‐line chemotherapy (PFS1) and overall survival (OS). Overall (N = 709), no impact of BMI was observed on PFS1 (p = .15), while BMI ≥ 30 was associated with worse OS (p = .003). In subjects who progressed to first line (N = 575), analyzing data across PFS1 quartiles and strata of disease burden, BMI predicted lower PFS1 in patients within the I PFS1 quartile and with the lowest disease burden (p = .001). Univariate analysis showed a detrimental effect of BMI ≥ 30 on OS for women within the I PFS1 quartile (p = .03). Results were confirmed in multivariate analysis. According to PFS1 quartiles a higher percentage of patients with high BMI and low disease burden progressed within 6 months of therapy. The effect of BMI on prognosis was also confirmed in multivariate analysis of OS for overall population. In our cohort, a BMI ≥ 30 correlated with worse OS in patients with HER2+ mBC who received pertuzumab and/or T‐DM1 but had no impact on PFS to first line. BMI predicted worse I PFS1 quartile.