Pembrolizumab in Patients With Advanced Triple-Negative Breast Cancer: Phase Ib KEYNOTE-012 Study

Prognostic impact of CD4-positive T cell subsets in early breast cancer: a study based on the FinHer trial patient population

Background

The clinical importance of tumor-infiltrating cluster of differentiation 4 (CD4) T cells is incompletely understood in early breast cancer. We investigated the clinical significance of CD4, forkhead box P3 (FOXP3), and B cell attracting chemokine leukocyte chemoattractant-ligand (C-X-C motif) 13 (CXCL13) in early breast cancer.

Methods

The study is based on the patient population of the randomized FinHer trial, where 1010 patients with early breast cancer were randomly allocated to adjuvant chemotherapy containing either docetaxel or vinorelbine, and human epidermal growth factor receptor 2 (HER2)-positive patients were also allocated to trastuzumab or no trastuzumab. Breast cancer CD4, FOXP3, and CXCL13 contents were evaluated using quantitative real-time polymerase chain reaction (qRT-PCR), and their influence on distant disease-free survival (DDFS) was examined using univariable and multivariable Cox regression and Kaplan-Meier estimates in the entire cohort and in selected molecular subgroups. Interactions between variables were analyzed using Cox regression. The triple-negative breast cancer (TNBC) subset of the HE10/97 randomized trial was used for confirmation.

Results

High CXCL13 was associated with favorable DDFS in univariable analysis, and independently in multivariable analysis (HR 0.44, 95% CI 0.29–0.67, P ≤ 0.001), most strongly in TNBC (HR 0.39, 95% CI 0.19–0.79, P = 0.009). No significant interaction with chemotherapy or trastuzumab administration was detected. Neither tumor CD4 content nor FOXP3 content was associated with DDFS. The favorable prognostic influence of CXCL13 was confirmed in the HE10/97 trial patient population with TNBC (HR 0.30, 95% CI 0.09–0.93; P = 0.038).

Conclusions

The results provide a high level of evidence that humoral immunity influences the survival outcomes of patients with early breast cancer, in particular of those with TNBC.

Trial registration

The study reports retrospective biomarker analyses in the prospective FinHer trial and the prospective HE10/97 trial.

ISRCTN76560285. Registered on 18 March 2005.

ACTRN12611000506998. Registered on 16 May 2011.

Electronic supplementary material

The online version of this article (10.1186/s13058-018-0942-x) contains supplementary material, which is available to authorized users.

Atezolizumab for the treatment of colorectal cancer: the latest evidence and clinical potential

INTRODUCTION

Atezolizumab is a fully humanized, engineered monoclonal antibody that specifically targets PD-L1, key molecule in the cancer-immunity pathway. Atezolizumab is currently approved for the treatment of metastatic non-small-cell lung cancer and advanced urothelial carcinomas. Areas covered: In this review, we will present the available data supporting the efficacy of atezolizumab for the treatment of metastatic colorectal cancer (mCRC). We will also provide an update on the ongoing/future clinical trials evaluating the role of atezolizumab for the treatment of CRC in different settings (alone or in combination with other checkpoint inhibitors and/or targeted therapies). So far, a small subgroup of mCRC (those with deficiency in mismatch repair - dMMR) appears to benefit significantly from checkpoint inhibitors. As expected, further research is needed to develop biomarkers, effective therapeutic strategies and novel combinations to overcome immune escape resistance and achieve better responses with minimal toxicities. Expert opinion: Interim analyses from ongoing early-phase studies in mCRC have shown encouraging activity of atezolizumab in combination with chemotherapy and/or targeted therapies, especially with MEK inhibitor cobimetinib. Within the next few years, this PD-L1 checkpoint inhibitor will likely be included as one of the treatment options for CRC, at least for patients with dMMR.

Expression of Programmed Death Ligand 1 (PD-L1) in Posttreatment Primary Inflammatory Breast Cancers and Clinical Implications

OBJECTIVES

Inflammatory breast carcinoma (IBC) is rare but is the most lethal type of breast cancer. Programmed death ligand 1 (PD-L1) expression in IBCs has been understudied.

METHODS

In this study, tissue microarrays of 68 IBCs were immunostained with a PD-L1 antibody using an antibody clone (28-8) and detection system approved by the US Food and Drug Administration for selecting patients with non-small cell lung cancer and melanoma for anti-PD-L1 therapy.

RESULTS

Positive PD-L1 expression was found in 25 (36.8%) of 68 samples but was not significantly associated with the clinicopathologic variables examined. Univariate analysis of overall survival (OS) revealed that worse OS was significantly associated with positive PD-L1, negative estrogen receptor, and triple-negative status. The 5-year OS rate was 36.4% for patients with PD-L1-positive IBC and 47.3% for those with PD-L1-negative IBC. In multivariate analyses, PD-L1 status remained a statistically independent predictor of OS.

CONCLUSIONS

These findings indicate that PD-L1 inhibitors could potentially improve the clinical outcome of patients with PD-L1-positive IBC.

[PD-L1 expression and PD-1/PD-L1 inhibitors in breast cancer]

The development of immune checkpoints inhibitors represents one of the major recent advances in oncology. Monoclonal antibodies directed against the programmed cell death protein 1 (PD-1) or its ligand (PD-L1) provides durable disease control, particularly in melanoma, lung, kidney, bladder and head and neck cancers. The purpose of this review is to synthesize current data on the expression of PD-L1 in breast cancer and on the preliminary clinical results of PD-1/PD-L1 inhibitors in breast cancer patients. In breast cancer, PD-L1 expression is heterogeneous and is generally associated with the presence of tumor-infiltrating lymphocytes as well as the presence of poor-prognosis factors, such as young age, high grade, ER-negativity, PR-negativity, and HER-2 overexpression, high proliferative index, and aggressive molecular subtypes (triple negative, basal-like, HER-2-overexpressing). Its prognostic value remains controversial when assessed with immunohistochemistry, whereas it seems favorable in triple-negative cancers when assessed at the mRNA level. Early clinical trials with PD-1/PD-L1 inhibitors in breast cancer have shown efficacy in terms of tumor response and/or disease control in refractory metastatic breast cancers, notably in the triple-negative subtype. Many trials are currently underway, both in the metastatic and neo-adjuvant setting. A crucial issue is identification of biomarkers predictive of response to PD-1/PD-L1 inhibitors.

Harnessing the immune system in the battle against breast cancer

Breast cancer is the most prevalent malignancy in women and the second most common cause of cancer-related death worldwide. Despite major innovations in early detection and advanced therapeutics, up to 30% of women with node-negative breast cancer and 70% of women with node-positive breast cancer will develop recurrence. The recognition that breast tumors are infiltrated by a complex array of immune cells that influence their development, progression, and metastasis, as well as their responsiveness to systemic therapies has sparked major interest in the development of immunotherapies. In fact, not only the native host immune system can be altered to promote potent antitumor response, but also its components can be manipulated to generate effective therapeutic strategies. We present here a review of the major approaches to immunotherapy in breast cancers, both successes and failures, as well as new therapies on the horizon.

Eradication of Triple-Negative Breast Cancer Cells by Targeting Glycosylated PD-L1

Protein glycosylation provides proteomic diversity in regulating protein localization, stability, and activity; it remains largely unknown whether the sugar moiety contributes to immunosuppression. In the study of immune receptor glycosylation, we showed that EGF induces programmed death ligand 1 (PD-L1) and receptor programmed cell death protein 1 (PD-1) interaction, requiring β-1,3-N-acetylglucosaminyl transferase (B3GNT3) expression in triple-negative breast cancer. Downregulation of B3GNT3 enhances cytotoxic T cell-mediated anti-tumor immunity. A monoclonal antibody targeting glycosylated PD-L1 (gPD-L1) blocks PD-L1/PD-1 interaction and promotes PD-L1 internalization and degradation. In addition to immune reactivation, drug-conjugated gPD-L1 antibody induces a potent cell-killing effect as well as a bystander-killing effect on adjacent cancer cells lacking PD-L1 expression without any detectable toxicity. Our work suggests targeting protein glycosylation as a potential strategy to enhance immune checkpoint therapy.

A Comprehensive Immunologic Portrait of Triple-Negative Breast Cancer

Triple-negative breast cancer (TNBC) is a high-risk malignancy due to its high capacity for invasion and lack of targeted therapy. Immunotherapy continues to demonstrate efficacy in a variety of cancers, and thus may be a promising strategy for TNBC given the limited therapeutic options currently available for TNBC. In this study, we performed an exhaustive analysis of immunogenic signatures in TNBC based on 2 large-scale breast cancer (BC) genomic data. We compared enrichment levels of 26 immune cell activities and pathways among TNBC, non-TNBC, and normal tissue, and within TNBCs of different genotypic or phenotypic features. We found that almost all analyzed immune activities and pathways had significantly higher enrichment levels in TNBC than non-TNBC. Elevated enrichment of these immune activities and pathways was likely to be associated with better survival prognosis in TNBC. This study demonstrated that TNBC likely exhibits the strongest immunogenicity among BC subtypes, and thus warrants the immunotherapeutic option for TNBC.

The Role of Immune Escape and Immune Cell Infiltration in Breast Cancer

While detailed analysis of aberrant cancer cell signaling pathways and changes in cancer cell DNA has dominated the field of breast cancer biology for years, there now exists increasing evidence that the tumor microenvironment (TME) including tumor-infiltrating immune cells support the growth and development of breast cancer and further facilitate invasion and metastasis formation as well as sensitivity to drug therapy. Furthermore, breast cancer cells have developed different strategies to escape surveillance from the adaptive and innate immune system. These include loss of expression of immunostimulatory molecules, gain of expression of immunoinhibitory molecules such as PD-L1 and HLA-G, and altered expression of components involved in apoptosis. Furthermore, the composition of the TME plays a key role in breast cancer development and treatment response. In this review we will focus on i) the different immune evasion mechanisms used by breast cancer cells, ii) the role of immune cell infiltration in this disease, and (iii) implication for breast cancer-based immunotherapies.

Characteristics and outcomes of breast cancer patients enrolled in the National Cancer Institute Cancer Therapy Evaluation Program sponsored phase I clinical trials

PURPOSE

Breast cancer (BC) is the most commonly diagnosed cancer and the second leading cause of cancer-related death among women. Given the availability of approved therapies and abundance of phase II and III clinical trials, historically few BC patients have been referred for consideration of participation on a phase I trial. We were interested in determining whether clinical benefit rates differed in patients with BC from other patients enrolled in phase I trials.

METHODS

We performed a retrospective analysis of all Cancer Therapy Evaluation Program (CTEP) sponsored phase I trials from 1993 to 2012. We report an analysis of demographic variables, rates of response to treatment, grade 4 toxicities, and treatment-related deaths.

RESULTS

De-identified data from 8087 patients were analyzed, with 1,376 having a diagnosis of BC. The median time from initial cancer diagnosis to enrollment in a CTEP-sponsored phase I clinical trial was 614 days for all patients. Breast cancer patients were enrolled on average 790 days after initial diagnosis, while non-BC patients had a median enrollment time of 582 days (p < 0.001). Breast cancer patients had more clinical responses than non-BC patients (18.3% vs. 4.3%, respectively). Along with the higher rate of response, BC patients remained on phase I trials longer than non-BC patients with a median of 70 days while the latter were on trial for a median of 57 days. The overall rate of death related to the treatment drugs was 0.47%.

CONCLUSIONS

Our data confirm our hypothesis that when compared to a general population of patients with cancer enrolled on phase I clinical trials, BC patients tend to derive clinical benefit from these therapies with similar toxicity profile. This evidence further supports enrollment of BC patients on phase I trials.

Immunotherapy in breast cancer: An introduction

The field of breast cancer immunology has progressed tremendously over the last decade. Twenty years ago immunotherapy was not considered for the treatment of breast cancers because breast cancer was not considered immunogenic. Today we know that most patients with breast cancer have some evidence of an adaptive immune response against their tumors, detectable either in the peripheral blood or in the tumor. Moreover, immunity to breast cancer begins at the earliest stages of the disease, in some patients prior to diagnosis. Recent evidence suggests that lymphocytes infiltrating breast cancers and found in the tumor stroma are strong prognostic indicators of a beneficial disease outcome. These observations now pave the way for the integration of immunomodulation into standard of care therapy for the treatment of breast cancer.

Breast Cancer Immunotherapy: Facts and Hopes

Immunotherapy is revolutionizing the management of multiple solid tumors, and early data have revealed the clinical activity of programmed cell death-1/programmed death ligand-1 (PD-1/PD-L1) antagonists in small numbers of patients with metastatic breast cancer. Clinical activity appears more likely if the tumor is triple negative, PD-L1+, and/or harbors higher levels of tumor-infiltrating leukocytes. Responses to atezolizumab and pembrolizumab appear to be durable in metastatic triple-negative breast cancer (TNBC), suggesting that these agents may transform the lives of responding patients. Current clinical efforts are focused on developing immunotherapy combinations that convert nonresponders to responders, deepen those responses that do occur, and surmount acquired resistance to immunotherapy. Identifying biomarkers that can predict the potential for response to single-agent immunotherapy, identify the best immunotherapy combinations for a particular patient, and guide salvage immunotherapy in patients with progressive disease are high priorities for clinical development. Smart clinical trials testing rational immunotherapy combinations that include robust biomarker evaluations will accelerate clinical progress, moving us closer to effective immunotherapy for almost all patients with breast cancer. Clin Cancer Res; 24(3); 511-20. ©2017 AACR.

Approach and management of checkpoint inhibitor-related immune hepatitis

Immune checkpoint inhibitors have promising clinical activity across multiple gastrointestinal cancers and immune-mediated hepatotoxicity is particularly relevant for this group of patients. In this article we will review the recognition, workup and management of suspected checkpoint inhibitor related immune-hepatitis.

Towards predictive biomarkers for immunotherapy response in breast cancer patients

Immunotherapy using anti-PD(L)1 has revolutionized treatment for various tumor types. Early data have shown durable responses in a small subgroup of breast cancer patients. So far, the response rates appear higher for breast tumors that are triple negative, PDL1-positive and/or harbor high levels of immune cells. Both comprehensive analyses of the breast tumor microenvironment and exploiting research on biomarkers in other cancer types, such as melanoma and lung cancer, may contribute to the discovery of accurate biomarkers to select breast cancer patients for immunotherapy. Here we summarize key features of the breast tumor microenvironment as well as putative predictive biomarkers established in other tumor types. Insights from both fields can guide future studies to enable personalized breast cancer immunotherapy.

Avelumab, an anti-PD-L1 antibody, in patients with locally advanced or metastatic breast cancer: a phase 1b JAVELIN Solid Tumor study

PURPOSE

Agents targeting programmed death receptor 1 (PD-1) or its ligand (PD-L1) have shown antitumor activity in the treatment of metastatic breast cancer (MBC). The aim of this study was to assess the activity of avelumab, a PD-L1 inhibitor, in patients with MBC.

METHODS

In a phase 1 trial (JAVELIN Solid Tumor; NCT01772004), patients with MBC refractory to or progressing after standard-of-care therapy received avelumab intravenously 10 mg/kg every 2 weeks. Tumors were assessed every 6 weeks by RECIST v1.1. Adverse events (AEs) were graded by NCI-CTCAE v4.0. Membrane PD-L1 expression was assessed by immunohistochemistry (Dako PD-L1 IHC 73-10 pharmDx).

RESULTS

A total of 168 patients with MBC, including 58 patients with triple-negative breast cancer (TNBC), were treated with avelumab for 2-50 weeks and followed for 6-15 months. Patients were heavily pretreated with a median of three prior therapies for metastatic or locally advanced disease. Grade ≥ 3 treatment-related AEs occurred in 13.7% of patients, including two treatment-related deaths. The confirmed objective response rate (ORR) was 3.0% overall (one complete response and four partial responses) and 5.2% in patients with TNBC. A trend toward a higher ORR was seen in patients with PD-L1+ versus PD-L1- tumor-associated immune cells in the overall population (16.7% vs. 1.6%) and in the TNBC subgroup (22.2% vs. 2.6%).

CONCLUSION

Avelumab showed an acceptable safety profile and clinical activity in a subset of patients with MBC. PD-L1 expression in tumor-associated immune cells may be associated with a higher probability of clinical response to avelumab in MBC.

Composite analysis of immunological and metabolic markers defines novel subtypes of triple negative breast cancer

Cancer biology is influenced by the tumor microenvironment, which impacts disease prognosis and therapeutic interventions. The inter-relationship of tumor-infiltrating lymphocytes, immune response regulators, and a glycolytic tumor environment was evaluated in a cohort of 183 largely consecutive patients with triple negative breast cancer diagnosis. High levels of tumor-infiltrating lymphocytes were associated with improved survival of triple negative breast cancer cases. However, elevated levels of PD-L1, CD163, and FOXP3 were individually associated with significantly decreased overall survival. These three determinants were significantly correlated, and could serve to differentiate the prognostic significance of tumor-infiltrating lymphocytes. Interestingly, a glycolytic tumor environment, as determined by the expression of MCT4 in the tumor stroma, was associated with the immune evasive environment and poor prognosis. Clustering of all markers defined four distinct triple negative breast cancer subtypes that harbored prognostic significance in multivariate analysis. Immune and metabolic markers stratified triple negative breast cancer into subtypes that have prognostic significance and implications for therapies targeting immune checkpoints and tumor metabolism.

Tackling Cancer Resistance by Immunotherapy: Updated Clinical Impact and Safety of PD-1/PD-L1 Inhibitors

Cancer therapy has been constantly evolving with the hope of finding the most effective agents with the least toxic effects to eradicate tumors. Cancer immunotherapy is currently among the most promising options, fulfilling this hope in a wide range of tumors. Immunotherapy aims to activate immunity to fight cancer in a very specific and targeted manner; however, some abnormal immune reactions known as immune-related adverse events (IRAEs) might occur. Therefore, many researchers are aiming to define the most proper protocols for managing these complications without interfering with the anticancer effect. One of these targeted approaches is the inhibition of the interaction between the checkpoint protein, programmed death-receptor 1 (PD-1), and its ligand, programmed death-ligand 1 (PD-L1), via a class of antibodies known as PD-1/PD-L1 inhibitors. These antibodies achieved prodigious success in a wide range of malignancies, including those where optimal treatment is not yet fully identified. In this review, we have critically explored and discussed the outcome of the latest PD-1 and PD-L1 inhibitor studies in different malignancies compared to standard chemotherapeutic alternatives with a special focus on the clinical efficacy and safety. The approval of the clinical applications of nivolumab, pembrolizumab, atezolizumab, avelumab, and durvalumab in the last few years clearly highlights the hopeful future of PD-1/PD-L1 inhibitors for cancer patients. These promising results of PD-1/PD-L1 inhibitors have encouraged many ongoing preclinical and clinical trials to explore the extent of antitumor activity, clinical efficacy and safety as well as to extend their applications.

Comparative aspects of canine and human inflammatory breast cancer

Inflammatory breast cancer (IBC) in humans is the most aggressive form of mammary gland cancer and shares clinical, pathologic, and molecular patterns of disease with canine inflammatory mammary carcinoma (CIMC). Despite the use of multimodal therapeutic approaches, including targeted therapies, the prognosis for IBC/CIMC remains poor. The aim of this review is to critically analyze IBC and CIMC in terms of biology and clinical features. While rodent cancer models have formed the basis of our understanding of cancer biology, the translation of this knowledge into improved outcomes has been limited. However, it is possible that a comparative "one health" approach to research, using a natural canine model of the disease, may help advance our knowledge on the biology of the disease. This will translate into better clinical outcomes for both species. We propose that CIMC has the potential to be a useful model for developing and testing novel therapies for IBC. Further, this strategy could significantly improve and accelerate the design and establishment of new clinical trials to identify novel and improved therapies for this devastating disease in a more predictable way.

Complimentary mechanisms of dual checkpoint blockade expand unique T-cell repertoires and activate adaptive anti-tumor immunity in triple-negative breast tumors

Triple-negative breast cancer (TNBC) is an aggressive and molecularly diverse breast cancer subtype typified by the presence of p53 mutations (∼80%), elevated immune gene signatures and neoantigen expression, as well as the presence of tumor infiltrating lymphocytes (TILs). As these factors are hypothesized to be strong immunologic prerequisites for the use of immune checkpoint blockade (ICB) antibodies, multiple clinical trials testing single ICBs have advanced to Phase III, with early indications of heterogeneous response rates of <20% to anti-PD1 and anti-PDL1 ICB. While promising, these modest response rates highlight the need for mechanistic studies to understand how different ICBs function, how their combination impacts functionality and efficacy, as well as what immunologic parameters predict efficacy to different ICBs regimens in TNBC. To address these issues, we tested anti-PD1 and anti-CTLA4 in multiple models of TNBC and found that their combination profoundly enhanced the efficacy of either treatment alone. We demonstrate that this efficacy is due to anti-CTLA4-driven expansion of an individually unique T-cell receptor (TCR) repertoire whose functionality is enhanced by both intratumoral Treg suppression and anti-PD1 blockade of tumor expressed PDL1. Notably, the individuality of the TCR repertoire was observed regardless of whether the tumor cells expressed a nonself antigen (ovalbumin) or if tumor-specific transgenic T-cells were transferred prior to sequencing. However, responsiveness was strongly correlated with systemic measures of tumor-specific T-cell and B-cell responses, which along with systemic assessment of TCR expansion, may serve as the most useful predictors for clinical responsiveness in future clinical trials of TNBC utilizing anti-PD1/anti-CTLA4 ICB.

The Hippo Pathway Component TAZ Promotes Immune Evasion in Human Cancer through PD-L1

The Hippo pathway component WW domain-containing transcription regulator 1 (TAZ) is a transcriptional coactivator and an oncogene in breast and lung cancer. Transcriptional targets of TAZ that modulate immune cell function in the tumor microenvironment are poorly understood. Here, we perform a comprehensive screen for immune-related genes regulated by TAZ and its paralog YAP using NanoString gene expression profiling. We identify the immune checkpoint molecule PD-L1 as a target of Hippo signaling. The upstream kinases of the Hippo pathway, mammalian STE20-like kinase 1 and 2 (MST1/2), and large tumor suppressor 1 and 2 (LATS1/2), suppress PD-L1 expression while TAZ and YAP enhance PD-L1 levels in breast and lung cancer cell lines. PD-L1 expression in cancer cell lines is determined by TAZ activity and TAZ/YAP/TEAD increase PD-L1 promoter activity. Critically, TAZ-induced PD-L1 upregulation in human cancer cells is sufficient to inhibit T-cell function. The relationship between TAZ and PD-L1 is not conserved in multiple mouse cell lines, likely due to differences between the human and mouse PD-L1 promoters. To explore the extent of divergence in TAZ immune-related targets between human and mouse cells, we performed a second NanoString screen using mouse cell lines. We show that many targets of TAZ may be differentially regulated between these species. These findings highlight the role of Hippo signaling in modifying human/murine physiologic/pathologic immune responses and provide evidence implicating TAZ in human cancer immune evasion.Significance: Human-specific activation of PD-L1 by a novel Hippo signaling pathway in cancer immune evasion may have a significant impact on research in immunotherapy. Cancer Res; 78(6); 1457-70. ©2018 AACR.

Immunotherapy, an evolving approach for the management of triple negative breast cancer: Converting non-responders to responders

Immunotherapy comprises a promising new era in cancer therapy. Immune checkpoint inhibitors targeting either the programmed death (PD)-1 receptor or its ligand PD-L1 were first approved by the Food and Drug Administration (FDA) for the management of metastatic melanoma in 2011. The approval of this class is being extended to include other types of immunogenic tumors. Although breast cancer (BC) was first categorized as non-immunogenic tumor type, there are certain subsets of BC that showed a high level of tumor infiltrating lymphocytes (TILs). Those subsets include the triple negative breast cancer (TNBC) and HER-2 positive breast tumors. Preliminary data from clinical trials presented promising outcomes for patients with advanced stage/metastatic TNBC. While the objective response rate (ORR) was relatively low, it is still promising because of the observation that the patients who respond to the treatment with immune checkpoint blockade have favorable prognosis and often show a significant increase in the overall survival. Therefore, the main challenge is to find ways to enhance the tumor response to such therapy and to convert the non-responders to responders. This will consequently bring new hopes for patients with advanced stage metastatic TNBC and help to decrease death tolls from this devastating disease. In the current review, we are highlighting and discussing the up-to-date strategies adopted at either the preclinical or the clinical settings to enhance tumor responsiveness to immunotherapy.

Integration of radiation and immunotherapy in breast cancer - Treatment implications

Radiation therapy (RT) has been successfully used in the treatment of breast cancer (BC) for over a century. While historically thought to be immunosuppressive, new data have shown that RT can work together with the immune system to eliminate cancer. It can cause immunogenic cell death and facilitate tumor neoantigen presentation and cross-priming of tumor-specific T-lymphocytes, turning irradiated tumor into an in-situ vaccine. Unfortunately, due to various immune escape mechanism put in place by the tumor, RT alone rarely results in a systemic response of metastatic disease sites (known as the abscopal effect). Immunotherapy, a series of agents designed to stimulate the immune system in order to generate tumor-specific immune response, is showing promise in treatment of various cancers, including BC, and can be an ideal complement to RT in stimulating a systemic immune response to reject the tumor cells. This review discusses the mechanisms in which RT can trigger an immune response for tumor rejection, and provide emerging preclinical and clinical data of combination immunoradiotherapy, and its potential in treating BC.

Heterogeneity of PD-L1 expression in primary tumors and paired lymph node metastases of triple negative breast cancer

Background

Programmed cell death ligand 1 (PD-L1) is a potential predictive biomarker of the response to anti-PD-L1/anti- programmed cell death 1 (PD-1) therapy in multiple cancers, including triple negative breast cancer(TNBC). The purpose of this study was to investigate whether PD-L1 expression is homogenous in primary tumors(PTs) and synchronous axillary lymph node metastases(LNMs) of TNBC.

Methods

PD-L1 expression was immunohistochemically evaluated in 101 TNBC patients’ PTs and paired LNMs. PD-L1 expression in tumor cells and infiltrating immune cells or node lymphocytes in the PTs and associated LNMs was scored separately and was correlated with patients’ clinical parameters and prognoses.

Results

PD-L1 expression exhibited spatial heterogeneity in both the tumor cells and the infiltrating immune cells or node lymphocytes of PTs and LNMs. The PD-L1 expression levels were significantly higher in the lymphocytes and tumor cells of the LNMs than in the PTs. PD-L1 expression was also more frequent among the LNMs. PD-L1 expression was associated with high grade and more stromal tumor-infiltrating lymphocytes(TILs). Furthermore, the disease-free survival and overall survival were similar between the PT- negative/LNM- positive and PT- positive/LNM- positive patients, both of which exhibited worse disease-free survival(DFS) thanPT -negative/LNM -negative patients.

Conclusions

The differential expression of PD-L1 between the PTs and LNMs suggests that LNMs PD-L1 status may be used to indicate whether PD-1/PD-L1-targeted therapy would be suitable for a node-positive TNBC patient in the future.

Electronic supplementary material

The online version of this article (10.1186/s12885-017-3916-y) contains supplementary material, which is available to authorized users.

Systemic therapy for brain metastases

Central nervous system metastases cause grave morbidity in patients with advanced malignancies. Lung cancer, breast cancer, and melanoma are the three most common causes of brain metastases. Although the exact incidence of brain metastases is unclear, there appears to be an increasing incidence which has been attributed to longer survival, better control of systemic disease, and better imaging modalities. Until recently surgical resection of solitary or symptomatic brain metastases, and radiation therapy (either whole-brain radiation therapy or stereotactic radiation) were the mainstay of treatment for patients with brain metastases. The majority of traditional chemotherapies have shown limited activity in the central nervous system, which has been attributed to the blood-brain barrier and the molecular structure of the used agents. The discovery of driver mutations and drugs targeting these mutations has changed the treatment landscape. Several of these targeted small-molecule tyrosine kinase inhibitors do cross the blood-brain barrier and/or have shown activity in the central nervous system. Another major advance in the care of brain metastases has been the advent of new immunotherapeutic agents, for which initial studies have shown intracranial activity. In this chapter, we will review the unique challenges in the treatment of brain metastases. The pertinent clinical studies of chemotherapy in brain metastases will be discussed. The currently reported clinical trials and evidence for use of targeted therapies and immunotherapeutic agents will be emphasized.

Triple negative breast cancer - prognostic role of immune-related factors: a systematic review

PURPOSE

Treatment of breast cancer has been increasingly successful in recent years with the advent of HER2-receptor targeted treatment and endocrine treatment. However, the triple negative subgroup of breast cancer (TNBC) (estrogen-, progesterone- and HER2-receptor negative) still lacks targeted treatment options. TNBC is a type of breast cancer that often affects younger women, and generally has a worse prognosis than other types of breast cancer. Recently, the complex role of the immune system in cancer growth, elimination and metastasis has been the object of increased attention. There is hope that a more detailed understanding of the intricate roles of the constituents of the immune system, will hold potential both as prognostic or predictive markers of cancer progression, but also as treatment targets for a wide range of tumors, including TNBC. The aim of this review is to provide an overview of the cellular immune microenvironment in TNBC, and to highlight areas in which TNBC may differ from other types of breast cancer.

MATERIAL AND METHODS

A search of PubMed was made using the terms 'triple negative breast cancer' and 'tumor infiltrating lymphocytes', 'CD8', 'CD4', 'B cells', 'natural killer cells', 'macrophages', myeloid derived suppressor cells', 'dendritic cells', 'immune check point inhibitor', 'CTLA-4' and 'PD-L1'.

RESULTS

We find that whilst factors such as TILs and certain subgroups of TILs (e.g., CD8 + and regulator T-cells) have been extensively researched, none of these markers are currently applicable to routine clinical practice. Also, TNBC differs from other types of breast cancer with regards to cellular composition of the immune infiltrate and PD-L1 expression, and the prognostic significance of these.

CONCLUSIONS

Immune-related factors have the potential as both prognostic and predictive biomarkers for new treatments targeting the immune system in breast cancer. However, multivariate analyses, taking other well-known factors into account, are required to determine the true value of these biomarkers. Also, differences between TNBC and other types of breast cancer may have implications for treatment and use of immune-related factors as biomarkers.

MUC1-C Induces PD-L1 and Immune Evasion in Triple-Negative Breast Cancer

The immune checkpoint ligand PD-L1 and the transmembrane mucin MUC1 are upregulated in triple-negative breast cancer (TNBC), where they contribute to its aggressive pathogenesis. Here, we report that genetic or pharmacological targeting of the oncogenic MUC1 subunit MUC1-C is sufficient to suppress PD-L1 expression in TNBC cells. Mechanistic investigations showed that MUC1-C acted to elevate PD-L1 transcription by recruitment of MYC and NF-κB p65 to the PD-L1 promoter. In an immunocompetent model of TNBC in which Eo771/MUC1-C cells were engrafted into MUC1 transgenic mice, we showed that targeting MUC1-C associated with PD-L1 suppression, increases in tumor-infiltrating CD8+ T cells and tumor cell killing. MUC1 expression in TNBCs also correlated inversely with CD8, CD69, and GZMB, and downregulation of these markers associated with decreased survival. Taken together, our findings show how MUC1 contributes to immune escape in TNBC, and they offer a rationale to target MUC1-C as a novel immunotherapeutic approach for TNBC treatment.Significance: These findings show how upregulation of the transmembrane mucin MUC1 contributes to immune escape in an aggressive form of breast cancer, with potential implications for a novel immunotherapeutic approach. Cancer Res; 78(1); 205-15. ©2017 AACR.

Pembrolizumab for the treatment of bladder cancer

INTRODUCTION

Until recently, patients with locally advanced or metastatic urothelial carcinoma after progression on cisplatin-containing chemotherapy had limited systemic treatment options with no significant survival benefit and poor tolerability. Advances in the field of immunotherapy with the introduction of checkpoint inhibitors have led to paradigm shifts in the treatment of various malignancies. Areas covered: The current review will summarize the clinical evidence of checkpoint inhibitors in bladder cancer, with a focus on pembrolizumab. Expert commentary: Category 1 evidence indicates that the checkpoint inhibitor pembrolizumab improves overall survival in patients with locally advanced or metastatic urothelial carcinoma who progressed after or during cisplatin-containing therapy as compared to current standard of care chemotherapy. Phase 1 and 2 evidence also indicates that checkpoint inhibitors are active in first line in patients who are ineligible for cisplatin-containing chemotherapy.

De novo metastasis in breast cancer: occurrence and overall survival stratified by molecular subtype

Breast cancer molecular subtypes, categorized jointly by hormone receptors (HR) and human epidermal growth factor-2 (HER2), are utilized to guide systemic therapy. We hypothesized distinct patterns of de novo metastasis and overall survival by molecular subtype using a retrospective cohort of 399,772 women in the National Cancer Database diagnosed with first primary invasive breast cancer between 2010 and 2014, of whom 13,924 were diagnosed with de novo metastasis from 2010 to 2013 and had follow up data. The relationship of molecular subtype with patient and tumor characteristics, including site of de novo metastasis, were examined using Chi-squared tests. Kaplan-Meier and Cox proportional hazards analyses were used to examine overall survival by molecular subtype. Bone was the most frequent de novo metastatic site for all molecular subtypes. Compared to HR+/HER2-, patients with HR-/HER2+ experienced 4.5, 3.0, and 6.0 times the de novo brain, lung, and liver metastasis respectively. In survival analyses of women diagnosed with de novo metastasis, the mortality risk relative to HR+/HER2- was twice as high for triple-negative (hazard ratio = 2.02, 95% CI 1.89-2.16) and modestly lower for HR+/HER2+ (hazard ratio = 0.83, 95% CI 0.78-0.88). The median survival difference between metastatic patients with and without chemotherapy was 28.6 months in HR+/HER2+ and 28.2 months in HR-/HER2+, but only 10.9 months in triple-negative and 5.2 months in HR+/HER2-. In conclusion, despite unfavorable patterns of de novo metastasis, HER2+ breast cancers had relatively better survival in recent years, probably due to treatment differences. Utilizing molecular subtype and site of de novo metastasis may predict prognosis and guide treatment.

The presence of PD-1 positive tumor infiltrating lymphocytes in triple negative breast cancers is associated with a favorable outcome of disease

Triple negative breast cancer patients have a poor course of disease not least because of limited treatment options however immunotherapy by targeting the PD-1/PD-L1 checkpoint system is a promising strategy to improve the outcome. Here we systematically investigated the expression of PD-1 on tumor infiltrating lymphocytes and PD-L1 on both tumor and infiltrated immune cells. Moreover, the PD-L1 gene status in tumor cells was assessed.

103 tissue microarray samples derived from triple negative breast cancer specimens were immunohistochemically stained against PD-1 and PD-L1. Dual marker fluorescence in-situ hybridization was applied to the PD-L1 gene and centromere region of chromosome 9. The disease free and overall survival rates were determined as a function of the PD-1/PD-L1 status.

A slight gain of the PD-L1 gene region was found in 55% of all samples but an elevated PD-L1/cen9 ratio was rather rare (7%). An increased gene dose is not associated with an enhanced protein expression and the PD-L1 expression only weakly correlates with the amount of immune cell infiltration. Instead, we found an association of PD-L1 expression on tumor and immune cells, respectively. Notably, the PD-1 expression on immune cells is associated with a favorable disease free and overall survival. PD-1 expression indicates an enhanced immunological anti-tumor activity and represents a favorable prognostic impact. A deeper understanding of factors that affect the regulation and function of the PD-1/PD-L1 system is required to establish predictive variables and to utilize the system for therapeutic intervention of triple negative breast cancer patients.

Immunotherapy in triple-negative breast cancer

Breast cancer can be classified based on the expression or lack of expression of protein receptors including estrogen receptor (ER), progesterone receptor (PR) and human epidermal growth receptor 2 (Her2). The basal molecular subtype is mostly made up of breast cancers that do not express ER/PR or Her2, triple-negative breast cancers (TNBC) (Bertucci et al. in Int J Cancer 123(1):236, 2008). TNBC tends to be more aggressive as there are no approved targeted treatments and the only treatment option currently is cytotoxic chemotherapy. Recent data show that some chemotherapies, specifically anthracyclines, not only have cytotoxic effects but also use the immune system by activating CD8+ T cell responses to kill cancer cells (Stagg et al. in Ther Adv Med Oncol 5(3):169-181, 2013), and thus, tumor-infiltrating lymphocytes respond well to chemotherapy. Currently, systemic immunotherapy which utilizes the patient's own immune system directly to eradicate and target neoplastic cells is being explored as treatment for TNBC as this type of breast cancer has been shown to be immunogenic (Yu et al. in Int J Environ Res Public Health 14:68, 2017). According to the Cancer Genome Atlas, TNBC has higher PD-L1 mRNA expression (Mittendorf et al. Cancer Immunol Res 2(4):361-370, 2014). Higher rates of CD8+ T cell infiltration were also found in TNBC according to a study by Liu et al. (Breast Cancer Res 14:R48, 2012). In TNBC patients, Pembrolizumab, a monoclonal antibody that targets programmed cell death protein 1 (PD-1), and Atezolizumab, a monoclonal antibody that targets its ligand, have been investigated to assess dose tolerability and side effects. Further studies involving vaccines, immunotherapy that targets cytotoxic T lymphocyte-associated protein-4 and PD-L1, are currently being investigated for treatment of TNBC. This review outlines the systemic immunotherapies that are currently being investigated for patients with TNBC.

PD-L1 Expression in TNBC: A Predictive Biomarker of Response to Neoadjuvant Chemotherapy?

Triple negative breast cancer (TNBC) has an aggressive clinical behaviour, with a poorer prognosis compared to other subtypes. Recently, tumor-infiltrating lymphocytes (TILs) have been proposed as a predictive biomarker for a better clinical outcome and pathological response (pR) after neoadjuvant chemotherapy (NACT) in TNBC. These data confirm the role of the immune system in the neoplastic progression and in the response to therapy. We performed a retrospective analysis of 54 pre-NACT biopsies of TNBC and compared both the percentage of stromal TILs and the degree of PD-L1 expression with the extent of pR to standard NACT. A pathological complete response (pCR) was achieved in 35% of cases. Univariate analysis showed (i) a significant association between PD-L1 expression in ≥25% of neoplastic cells and the achievement of a pCR (p = 0.024); (ii) a significantly higher frequency of pCR in cases showing ≥50% stromal TILs (p < 0.001). However in the multivariate analysis only PD-L1 expression on tumor cells remained significantly associated with pCR (OR = 1,13; 95% CI 1,01–1,27), suggesting that the expression of this biomarker could be associated with a subpopulation of TNBC more likely to respond to chemotherapy. These data need to be confirmed by larger studies.

HDAC inhibition potentiates immunotherapy in triple negative breast cancer

Triple-negative breast cancer (TNBC) represents a more aggressive and difficult subtype of breast cancer where responses to chemotherapy occur, but toxicity is significant and resistance often follows. Immunotherapy has shown promising results in various types of cancer, including breast cancer. Here, we investigated a new combination strategy where histone deacetylase inhibitors (HDACi) are applied with immune checkpoint inhibitors to improve immunotherapy responses in TNBC.

Testing different epigenetic modifiers, we focused on the mechanisms underlying HDACi as priming modulators of immunotherapy. Tumor cells were co-cultured with human peripheral blood mononuclear cells (PBMCs) and flow cytometric immunophenotyping was performed to define the role of epigenetic priming in promoting tumor antigen presentation and immune cell activation. We found that HDACi up-regulate PD-L1 mRNA and protein expression in a time-dependent manner in TNBC cells, but not in hormone responsive cells. Focusing on TNBC, HDACi up-regulated PD-L1 and HLA-DR on tumor cells when co-cultured with PBMCs and down-regulated CD4⁺ Foxp3⁺ Treg in vitro. HDACi significantly enhanced the in vivo response to PD-1/CTLA-4 blockade in the triple-negative 4T1 breast cancer mouse model, the only currently available experimental system with functional resemblance to human TNBC. This resulted in a significant decrease in tumor growth and increased survival, associated with increased T cell tumor infiltration and a reduction in CD4⁺ Foxp3⁺ T cells in the tumor microenvironment. Overall, our results suggest a novel role for HDAC inhibition in combination with immune checkpoint inhibitors and identify a promising therapeutic strategy, supporting its further clinical evaluation for TNBC treatment.

The MAPK hypothesis: immune-regulatory effects of MAPK-pathway genetic dysregulations and implications for breast cancer immunotherapy

With the advent of checkpoint inhibition, immunotherapy has revolutionized the clinical management of several cancers, but has demonstrated limited efficacy in mammary carcinoma. Transcriptomic profiling of cancer samples defined distinct immunophenotypic categories characterized by different prognostic and predictive connotations. In breast cancer, genomic alterations leading to the dysregulation of mitogen-activated protein kinase (MAPK) pathways have been linked to an immune-silent phenotype associated with poor outcome and treatment resistance. These aberrations include mutations of MAP3K1 and MAP2K4, amplification of KRAS, BRAF, and RAF1, and truncations of NF1. Anticancer therapies targeting MAPK signaling by BRAF and MEK inhibitors have demonstrated clear immunologic effects. These off-target properties could be exploited to convert the immune-silent tumor phenotype into an immune-active one. Preclinical evidence supports that MAPK-pathway inhibition can dramatically increase the efficacy of immunotherapy. In this review, we provide a detailed overview of the immunomodulatory impact of MAPK-pathway blockade through BRAF and MEK inhibitions. While BRAF inhibition might be relevant in melanoma only, MEK inhibition is potentially applicable to a wide range of tumors. Context-dependent similarities and differences of MAPK modulation will be dissected, in light of the complexity of the MAPK pathways. Therapeutic strategies combining the favorable effects of MAPK-oriented interventions on the tumor microenvironment while maintaining T-cell function will be presented. Finally, we will discuss recent studies highlighting the rationale for the implementation of MAPK-interference approaches in combination with checkpoint inhibitors and immune agonists in breast cancer.

CD14+ HLA-DR-/low MDSCs are elevated in the periphery of early-stage breast cancer patients and suppress autologous T cell proliferation

PURPOSE

Despite the recent expansion in the use of immunotherapy for many cancer types, it is still not a standard treatment for breast cancer. Identifying differences in the immune systems of breast cancer patients compared to healthy women might provide insight into potential targets for immunotherapy and thus may assist its clinical implementation.

METHODS

Multi-colour flow cytometry was used to investigate myeloid and lymphoid populations in the peripheral blood of breast cancer patients (n = 40) and in the blood of healthy age-matched women (n = 25). We additionally performed functional testing to identify immune suppressive mechanisms used by circulating CD14+ myeloid cells from breast cancer patients.

RESULTS

Our results show that breast cancer patients have significantly elevated frequencies of cells with the monocytic myeloid-derived suppressor cell (mMDSC) phenotype CD14+ HLA-DR-/low compared with healthy women (p < 0.01). We also observed higher levels of earlier differentiated T cells and correspondingly lower levels of T cells in later stages of differentiation (p < 0.05). These disease-associated differences could already be detected in early-stage breast cancer patients in stages 1 and 2 (n = 33 of 40) (p < 0.05). Levels of circulating T cells correlated with certain clinical features and with patient age (p < 0.05). Functional tests showed that CD14+ myeloid cells from breast cancer patients more potently suppressed autologous T cell proliferation than CD14+ cells from healthy women (p < 0.01). Subsequent investigation determined that suppression was mediated in part by reactive oxygen species, because inhibiting this pathway partially restored T cell proliferation (p < 0.01).

CONCLUSION

Our results highlight the potential importance of cells with mMDSC phenotypes in breast cancer, identifiable already at early stages of disease. This may provide a basis for identifying possible new therapeutic targets to enhance anti-cancer immunity.

Tumour-infiltrating lymphocytes and prognosis in different subtypes of breast cancer: a pooled analysis of 3771 patients treated with neoadjuvant therapy

BACKGROUND

Tumour-infiltrating lymphocytes (TILs) are predictive for response to neoadjuvant chemotherapy in triple-negative breast cancer (TNBC) and HER2-positive breast cancer, but their role in luminal breast cancer and the effect of TILs on prognosis in all subtypes is less clear. Here, we assessed the relevance of TILs for chemotherapy response and prognosis in patients with TNBC, HER2-positive breast cancer, and luminal-HER2-negative breast cancer.

METHODS

Patients with primary breast cancer who were treated with neoadjuvant combination chemotherapy were included from six randomised trials done by the German Breast Cancer Group. Pretherapeutic core biopsies from 3771 patients included in these studies were assessed for the number of stromal TILs by standardised methods according to the guidelines of the International TIL working group. TILs were analysed both as a continuous parameter and in three predefined groups of low (0-10% immune cells in stromal tissue within the tumour), intermediate (11-59%), and high TILs (≥60%). We used these data in univariable and multivariable statistical models to assess the association between TIL concentration and pathological complete response in all patients, and between the amount of TILs and disease-free survival and overall survival in 2560 patients from five of the six clinical trial cohorts.

FINDINGS

In the luminal-HER2-negative breast cancer subtype, a pathological complete response (pCR) was achieved in 45 (6%) of 759 patients with low TILs, 48 (11%) of 435 with intermediate TILs, and 49 (28%) of 172 with high TILs. In the HER2-positive subtype, pCR was observed in 194 (32%) of 605 patients with low TILs, 198 (39%) of 512 with intermediate TILs, and 127 (48%) of 262 with high TILs. Finally, in the TNBC subtype, pCR was achieved in 80 (31%) of 260 patients with low TILs, 117 (31%) of 373 with intermediate TILs, and 136 (50%) of 273 with high TILs (p<0·0001 for each subtype, χ² test for trend). In the univariable analysis, a 10% increase in TILs was associated with longer disease-free survival in TNBC (hazard ratio [HR] 0·93 [95% CI 0·87-0·98], p=0·011) and HER2-positive breast cancer (0·94 [0·89-0·99], p=0·017), but not in luminal-HER2-negative tumours (1·02 [0·96-1·09], p=0·46). The increase in TILs was also associated with longer overall survival in TNBC (0·92 [0·86-0·99], p=0·032), but had no association in HER2-positive breast cancer (0·94 [0·86-1·02], p=0·11), and was associated with shorter overall survival in luminal-HER2-negative tumours (1·10 [1·02-1·19], p=0·011).

INTERPRETATION

Increased TIL concentration predicted response to neoadjuvant chemotherapy in all molecular subtypes assessed, and was also associated with a survival benefit in HER2-positive breast cancer and TNBC. By contrast, increased TILs were an adverse prognostic factor for survival in luminal-HER2-negative breast cancer, suggesting a different biology of the immunological infiltrate in this subtype. Our data support the hypothesis that breast cancer is immunogenic and might be targetable by immune-modulating therapies. In light of the results in luminal breast cancer, further research investigating the interaction of the immune system with different types of endocrine therapy is warranted.

FUNDING

Deutsche Krebshilfe and European Commission.

Identifying a Clinically Applicable Mutational Burden Threshold as a Potential Biomarker of Response to Immune Checkpoint Therapy in Solid Tumors

PURPOSE

An association between mutational burden and response to immune checkpoint therapy has been documented in several cancer types. The potential for such a mutational burden threshold to predict response to immune checkpoint therapy was evaluated in several clinical datasets, where mutational burden was measured either by whole-exome sequencing (WXS) or using commercially available sequencing panels.

METHODS

WXS and RNA-seq data of 33 solid cancer types from TCGA were analyzed to determine whether a robust immune checkpoint activating mutation (iCAM) burden threshold associated with evidence of immune checkpoint activation exists in these cancers that may serve as a biomarker for response to immune checkpoint blockade therapy.

RESULTS

We find that a robust iCAM threshold, associated with signatures of immune checkpoint activation, exists in 8 of 33 solid cancers: melanoma, lung adenocarcinoma, colon adenocarcinoma, endometrial cancer, stomach adenocarcinoma, cervical cancer, ER+HER2- breast cancer, and bladder-urothelial cancer. Tumors with mutational burden higher than the threshold (iCAM+) also had clear histologic evidence of lymphocytic infiltration. In published datasets of melanoma, lung adenocarcinoma and colon cancer, patients with iCAM+ tumors had significantly better response to immune checkpoint therapy compared to those with iCAM- tumors. ROC analysis using TCGA predictions as gold standard showed that iCAM+ tumors are accurately identifiable using clinical sequencing assays, such as FoundationOne or StrandAdvantage. Using the FoundationOne derived threshold, analysis of 113 melanoma tumors, showed that iCAM+ patients have significantly better response to immune checkpoint therapy. iCAM+ and iCAM- tumors have distinct mutation patterns and different immune microenvironments.

CONCLUSION

In 8 solid cancers, a mutational burden threshold exists that may predict response to immune checkpoint blockade. This threshold is identifiable using available clinical sequencing assays.

Immunotherapy for Breast Cancer: Current and Future Strategies

PURPOSE OF REVIEW

The breast tumor microenvironment is immunosuppressive and is increasingly recognized to play a significant role in tumorigenesis. A deeper understanding of normal and aberrant interactions between malignant and immune cells has allowed researchers to harness the immune system with novel immunotherapy strategies, many of which have shown promise in breast cancer. This review discusses the application of immunotherapy to the treatment of breast cancer.

RECENT FINDINGS

Both basic science and clinical trial data are rapidly developing in the use of immunotherapy for breast cancer. The current clinical trial landscape includes therapeutic vaccines, immune checkpoint blockade, antibodies, cytokines, and adoptive cell therapy.

SUMMARY

Despite early failures, the application of immunotherapeutic strategies to the treatment of breast cancer holds promise.

Novel Targeted Agents and Immunotherapy in Breast Cancer

The treatment of breast cancer is generally determined according to breast cancer subtype: hormone receptor-positive (luminal), triple-negative (basal-like), and HER2-overexpressing breast cancer. Recent years have seen the development of exciting novel and potent therapeutics based on molecular pathways, immune modulation, and antibody conjugates. In this article, we cover new and emerging therapeutic areas and ongoing clinical trials that may result in further improvements in breast cancer outcomes.

Expression of programmed death-1 in sentinel lymph nodes of breast cancer

BACKGROUND AND OBJECTIVES

To explore whether lymphocytes in sentinel lymph nodes (SLNs) are highly exposed to tumor neoantigens and thus express high level of programmed death 1 (PD-1), we examined PD-1 expression in SLNs and non-sentinel regional lymph nodes (non-SLNs) in breast cancer.

METHODS

We performed PD-1 immunohistochemistry in two cohorts: 40 metastasis-negative SLNs including 10 patients for each subtype (luminal A-like, luminal B-like, HER2, and triple negative breast cancer [TNBC]); and 25 pairs of metastasis-positive SLNs and non-SLNs (10 luminal A-like, 10 luminal B-like, and 5 TNBC).

RESULTS

Among 40 metastasis-negative SLNs, 34 and 6 samples were PD-1 intensity grade 1 (low) and 2 (high), respectively. PD-1 intensity correlated with PD-1-positive lymphocyte numbers (P = 0.005); TNBC had the highest PD-1 lymphocyte numbers among all subtypes. The median PD-1-positive lymphocyte number was higher in SLNs than non-SLNs. In most cases, more lymphocytes in SLNs expressed PD-1 than those in non-SLNs (P < 0.0001).

CONCLUSIONS

TNBC had the greatest PD-1 expression among all subtypes, and metastasis-positive SLNs had more PD-1-positive lymphocytes than downstream non-SLNs. These data suggested that lymphocytes in SLNs are activated following exposure to tumor neoantigens and thus tumor specific, and could be utilized as a biomarker platform.