Relevance of tumor-infiltrating lymphocytes in breast cancer

PlexinB1 Inactivation Reprograms Immune Cells in the Tumor Microenvironment, Inhibiting Breast Cancer Growth and Metastatic Dissemination

Semaphorin-plexin signaling plays a major role in the tumor microenvironment (TME). In particular, Semaphorin 4D (SEMA4D) has been shown to promote tumor growth and metastasis; however, the role of its high-affinity receptor Plexin-B1 (PLXNB1), which is expressed in the TME, is poorly understood. In this study, we directly targeted PLXNB1 in the TME of triple-negative murine breast carcinoma to elucidate its relevance in cancer progression. We found that primary tumor growth and metastatic dissemination were strongly reduced in PLXNB1-deficient mice, which showed longer survival. PLXNB1 loss in the TME induced a switch in the polarization of tumor-associated macrophages (TAM) toward a pro-inflammatory M1 phenotype and enhanced the infiltration of CD8+ T lymphocytes both in primary tumors and in distant metastases. Moreover, PLXNB1 deficiency promoted a shift in the Th1/Th2 balance of the T-cell population and an antitumor gene signature, with the upregulation of Icos, Perforin-1, Stat3, and Ccl5 in tumor-infiltrating lymphocytes (TILs). We thus tested the translational relevance of TME reprogramming driven by PLXNB1 inactivation for responsiveness to immunotherapy. Indeed, in the absence of PLXNB1, the efficacy of anti-PD-1 blockade was strongly enhanced, efficiently reducing tumor growth and distant metastasis. Consistent with this, pharmacological PLXNB1 blockade by systemic treatment with a specific inhibitor significantly hampered breast cancer growth and enhanced the antitumor activity of the anti-PD-1 treatment in a preclinical model. Altogether, these data indicate that PLXNB1 signaling controls the antitumor immune response in the TME and highlight this receptor as a promising immune therapeutic target for metastatic breast cancers.

Treatment-Related Lymphopenia is Possibly a Marker of Good Prognosis in Nasopharyngeal Carcinoma: a Propensity-Score Matching Analysis

Purpose

The aims of the study were to monitor circulating lymphocyte subset counts before and after therapy for nasopharyngeal carcinoma (NPC), and investigate their relationships with patient outcomes.

Patients and Methods

Subjects comprised patients with TNM stage I-IVA NPC who underwent radiotherapy. Peripheral venous blood samples were collected before and after treatment. Lymphocyte subset counts were analyzed by flow cytometry. Differences between post-treatment and baseline counts were calculated to determine Δ values. Patients were divided into high and low groups, based on median lymphocyte subset counts; propensity score matching was applied to balance groups. Progression-free survival (PFS) and overall survival (OS) were plotted using Kaplan-Meier curves and compared using a Log rank test. Relationships between lymphocyte subset counts and patient survival were subjected to Cox regression analysis.

Results

Patients with NPC (n=746) were enrolled from 2012-2022. Higher CD8+ and total T cell baseline counts were associated with better 5-year PFS (73.7% vs 63.1%, P=0.002 and 73.8% vs 64.1%, P=0.005, respectively). Similarly, higher Δ values of CD4+ and total T cells were associated with higher 5-year PFS (76.2% vs 63.5%, P=0.001; 74.3% vs 65.4%, P=0.010) and OS (89.8% vs 81.6%, P=0.005; 88.6% vs 82.5%, P=0.009). Multivariate Cox regression revealed that CD8+ (hazard ratio (HR) 0.651, P=0.002) and total T (HR 0.600, P<0.001) cells were significantly associated with PFS. CD4+ (HR 0.708, P=0.038) and total T (HR 0.639, P=0.031) cells were independent prognostic factors for OS.

Conclusion

NPC patients with low total or CD8+ T cell counts before treatment had worse prognosis; however, those with more significant decreases in total or CD4+ T cells possibly had better outcomes. T cell counts can be reliable indicators to predict prognosis.

The potent potential of MFAP2 in prognosis and immunotherapy of triple-negative breast cancer

BACKGROUNDS

Microfibril-associated protein 2 (MFAP2) is a protein presenting in the extracellular matrix that governs the activity of microfibrils through its interaction with fibrillin. While the involvement of MFAP2 in metabolic disorders has been documented, its expression and prognostic significance in triple-negative breast cancer (TNBC) remain unexplored.

METHODS

We acquired datasets pertaining to breast cancer (BC) from the Gene Expression Omnibus (GEO) and The Cancer Genome Atlas (TCGA) databases. Next, a Venn diagram was used to identify the differentially expressed genes (DEGs). The DEGs were used to perform Gene Ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG), protein-protein interaction (PPI), immune and survival analysis. The expressions of MFAP2, PD-1 and PD-L1 were examined by immunohistochemistry and western blot and their relationship with clinical pathological parameters were analyzed by clinical specimen samples from patients with TNBC. Tumor Immune Estimation Resource (TIMER, https://cistrome.shinyapps.io/timer/ ) was adopted to calculate the immune infiltration level of TNBC. The link between gene expression and tumor mutational burden (TMB) was described using Spearman's correlation analysis.

RESULTS

We identified 66 differentially expressed genes (DEGs) that were up-regulated. Among these DEGs, MFAP2 was found to be overexpressed in TNBC and was associated with a lower probability of survival. This finding was confirmed through the use of immunohistochemistry and western blot techniques. Additionally, MFAP2 was found to be related to various pathological parameters in TNBC patients. Mechanistically, gene set enrichment analysis (GSEA) revealed that MFAP2 primarily influenced cellular biological behavior in terms of epithelial mesenchymal transition, glycolysis, and apical junction. Notably, MFAP2 expression was positively correlated with the abundance of macrophages, while a negative correlation was observed with the abundance of B cells, CD4 + T cells, CD8 + T cells, neutrophils and dendritic cells through immune analysis. Furthermore, it was observed that MFAP2 displayed a negative correlation not only with tumor mutational burden (TMB), a recognized biomarker for PD-1/PD-L1 immunotherapy, but also with PD-L1 in samples of TNBC.

CONCLUSION

MFAP2 may be an important prognostic biomarker for TNBC, as well as a viable target for immunotherapy in this disease.

IFI30 as a key regulator of PDL1 immunotherapy prognosis in breast cancer

BACKGROUND

IFI30 is a lysosomal thiol reductase involved in antigen presentation and immune regulation in various cancers, including breast cancer. Despite its known involvement, the precise mechanism, function, and relationship with the PD-L1 axis and immune response remain unclear.

METHODS

We conducted an extensive investigation into IFI30 mRNA expression in breast cancer utilizing data from The Cancer Genome Atlas (TCGA) and Genotype-Tissue Expression (GTEx) databases. Furthermore, we characterized IFI30 mRNA expression across various cell types using publicly available single-cell RNA sequencing datasets, and assessed protein expression through immunohistochemistry using an in-house breast cancer tissue microarray. Functional experiments were performed to elucidate the effects of IFI30 overexpression on PD-L1 expression and inhibitory efficacy in both macrophages and breast tumor cells.

RESULTS

Our study unveiled a marked upregulation of IFI30 expression in breast cancer tissues compared to their normal counterparts, with notable associations identified with tumor stage and prognosis. Additionally, IFI30 expression demonstrated significant correlations with various immune-related signaling pathways, encompassing peptide antigen binding, cytokine binding, and MHC class II presentation. Notably, breast cancer samples exhibiting high IFI30 expression in tumor cells displayed high PD-L1 expression on corresponding cells, alongside a diminished ratio of CD8 + T cell infiltration within the tumor microenvironment. Furthermore, ectopic knockdown of IFI30 in both tumor cells and macrophages resulted in a reduction of PD-L1 expression, while conversely, overexpression of IFI30 led to an increase in PD-L1 expression.

CONCLUSIONS

This study offers new insights into the involvement of IFI30 in breast cancer, elucidating its interplay with the PD-L1 axis and immune response dynamics. Our findings suggest that modulation of the IFI30-PD-L1 axis could serve as a promising strategy for regulating T cells infiltration in breast cancer thus treating breast cancer.

Drug repositioning for immunotherapy in breast cancer using single-cell analysis

Immunomodulatory peptides, while exhibiting potential antimicrobial, antifungal, and/or antiviral properties, can play a role in stimulating or suppressing the immune system, especially in pathological conditions like breast cancer (BC). Thus, deregulation of these peptides may serve as an immunotherapeutic strategy to enhance the immune response. In this meta-analysis, we utilized single-cell RNA sequencing data and known therapeutic peptides to investigate the deregulation of these peptides in malignant versus normal human breast epithelial cells. We corroborated our findings at the chromatin level using ATAC-seq. Additionally, we assessed the protein levels in various BC cell lines. Moreover, our in-house drug repositioning approach was employed to identify potential drugs that could positively impact the relapse-free survival of BC patients. Considering significantly deregulated therapeutic peptides and their role in BC pathology, our approach aims to downregulate B2M and SLPI, while upregulating PIGR, DEFB1, LTF, CLU, S100A7, and SCGB2A1 in BC epithelial cells through our drug repositioning pipeline. Leveraging the LINCS L1000 database, we propose BRD-A06641369 for B2M downregulation and ST-4070043 and BRD-K97926541 for SLPI downregulation without negatively affecting the MHC complex as a significantly correlated pathway with these two genes. Furthermore, we have compiled a comprehensive list of drugs for the upregulation of other selected immunomodulatory peptides. Employing an immunotherapeutic approach by integrating our drug repositioning pipeline with single-cell analysis, we proposed potential drugs and drug targets to fortify the immune system against BC.

Tumor microenvironment and immune system preservation in early-stage breast cancer: routes for early recurrence after mastectomy and treatment for lobular and ductal forms of disease

BACKGROUND

Intra-ductal cancer (IDC) is the most common type of breast cancer, with intra-lobular cancer (ILC) coming in second. Surgery is the primary treatment for early stage breast cancer. There are now irrefutable data demonstrating that the immune context of breast tumors can influence growth and metastasis. Adjuvant chemotherapy may be administered in patients who are at a high risk of recurrence. Our goal was to identify the processes underlying both types of early local recurrences.

METHODS

This was a case-control observational study. Within 2 years of receiving adjuvant taxan and anthracycline-based chemotherapy, as well as modified radical mastectomy (MRM), early stage IDC and ILC recurred. Vimentin, α-smooth muscle actin (SMA), platelet-derived growth factor (PDGF), matrix metalloproteinase (MMP1), and clustered differentiation (CD95) were investigated.

RESULTS

Of the samples in the ductal type group, 25 showed local recurrence, and 25 did not. Six individuals in the lobular-type group did not experience recurrence, whereas seven did. Vimentin (p = 0.000 and 0.021), PDGF (p = 0.000 and 0.002), and CD95 (p = 0.000 and 0.045) expressions were significantly different in ductal and lobular carcinoma types, respectively. Measurement of ductal type was the sole significant difference found in MMP1 (p = 0.000) and α-SMA (p = 0.000). α-SMA and CD95 were two variables that helped the recurrence mechanism in the ductal type according to the pathway analysis. In contrast, the CD95 route is a recurrent mechanism for the lobular form.

CONCLUSIONS

While the immune system plays a larger role in ILC, the tumor microenvironment and immune system both influence the recurrence of IDC. According to this study, improving the immune system may be a viable cancer treatment option.

Single-cell and spatial profiling identify three response trajectories to pembrolizumab and radiation therapy in triple negative breast cancer

Strategies are needed to better identify patients that will benefit from immunotherapy alone or who may require additional therapies like chemotherapy or radiotherapy to overcome resistance. Here we employ single-cell transcriptomics and spatial proteomics to profile triple negative breast cancer biopsies taken at baseline, after one cycle of pembrolizumab, and after a second cycle of pembrolizumab given with radiotherapy. Non-responders lack immune infiltrate before and after therapy and exhibit minimal therapy-induced immune changes. Responding tumors form two groups that are distinguishable by a classifier prior to therapy, with one showing high major histocompatibility complex expression, evidence of tertiary lymphoid structures, and displaying anti-tumor immunity before treatment. The other responder group resembles non-responders at baseline and mounts a maximal immune response, characterized by cytotoxic T cell and antigen presenting myeloid cell interactions, only after combination therapy, which is mirrored in a murine model of triple negative breast cancer.

CCL2 chemokine inhibition primes the tumor vasculature for improved nanomedicine delivery and efficacy

Blood vessel functionality is crucial for efficient tumor-targeted drug delivery. Heterogeneous distribution and perfusion of angiogenic blood vessels contribute to suboptimal accumulation of (nano-) therapeutics in tumors and metastases. To attenuate pathological angiogenesis, an L-RNA aptamer inhibiting the CC motif chemokine ligand 2 (CCL2) was administered to mice bearing orthotopic 4T1 triple-negative breast cancer tumors. The effect of CCL2 inhibition on tumor blood vessel functionality and tumor-targeted drug delivery was evaluated via multimodal and multiscale optical imaging, employing fluorophore-labeled polymeric (10 nm) and liposomal (100 nm) nanocarriers. Anti-CCL2 treatment induced a dose-dependent anti-angiogenic effect, reflected by a decreased relative blood volume, increased blood vessel maturity and functionality, and reduced macrophage infiltration, accompanied by a shift in the polarization of tumor-associated macrophages (TAM) towards a less M2-like and more M1-like phenotype. In line with this, CCL2 inhibitor treatment improved the delivery of polymers and liposomes to tumors, and enhanced the antitumor efficacy of free and liposomal doxorubicin. Together, these findings demonstrate that blocking the CCL2-CCR2 axis modulates TAM infiltration and polarization, resulting in vascular normalization and improved tumor-targeted drug delivery.

The tumor-derived cytokine Chi3l1 induces neutrophil extracellular traps that promote T cell exclusion in triple-negative breast cancer

In triple-negative breast cancer (TNBC), stromal restriction of CD8+ T cells associates with poor clinical outcomes and lack of responsiveness to immune-checkpoint blockade (ICB). To identify mediators of T cell stromal restriction, we profiled murine breast tumors lacking the transcription factor Stat3, which is commonly hyperactive in breast cancers and promotes an immunosuppressive tumor microenvironment. Expression of the cytokine Chi3l1 was decreased in Stat3-/- tumors. CHI3L1 expression was elevated in human TNBCs and other solid tumors exhibiting T cell stromal restriction. Chi3l1 ablation in the polyoma virus middle T (PyMT) breast cancer model generated an anti-tumor immune response and delayed mammary tumor onset. These effects were associated with increased T cell tumor infiltration and improved response to ICB. Mechanistically, Chi3l1 promoted neutrophil recruitment and neutrophil extracellular trap formation, which blocked T cell infiltration. Our findings provide insight into the mechanism underlying stromal restriction of CD8+ T cells and suggest that targeting Chi3l1 may promote anti-tumor immunity in various tumor types.

Tumor Antigen-Primed Dendritic Cell-Derived Exosome Synergizes with Colony Stimulating Factor-1 Receptor Inhibitor by Modulating the Tumor Microenvironment and Systemic Immunity

Dendritic cell-derived exosomes (Dex) have overcome the disadvantages associated with dendritic cell (DC) vaccines, such as cost effectiveness, stability, and sensitivity to the systemic microenvironment. However, in clinical trials, Dex failed to provide satisfactory results because of many reasons, including inadequate maturation of DC as well as the immunosuppressive tumor microenvironment (TME). Hence, culturing DCs in the presence of a maturation cocktail showed an induced expression of MHCs and co-stimulatory molecules. Additionally, targeting the colony stimulating factor-1 (CSF-1)/CSF-1 receptor (CSF-1R) signaling pathway by a CSF-1R inhibitor could deplete tumor-associated macrophages (TAMs) and myeloid-derived suppressor cells (MDSCs) which are responsible for immunosuppressive TME. Hence, in this study, mDexTA were isolated from bone marrow-derived DC cultured in the presence of a novel maturation cocktail and tumor antigen. mDexTA showed elevated expression of major histocompatibility complexes (MHCs) and co-stimulatory molecules and was found capable of activating naïve DC and T cells in vitro more efficiently when compared to imDexTA isolated from immature DCs. In addition, PLX-3397, a small molecule inhibitor of CSF-1/CSF-1R, was used in combination to enhance the antitumor efficacy of mDexTA. PLX-3397 showed dose-dependent toxicity against bone marrow-derived macrophages (BMDMs). In the B16-F10 murine melanoma model, we found that the combination treatment delayed tumor growth and improved survival compared to the mice treated with mDexTA alone by enhancing the CD8 T cells infiltration in TME. mDexTA when combined with PLX-3397 modulated the TME by shifting the Th1/Th2 toward a dominant Th1 population and depleting the TAMs and MDSCs. Interestingly, PLX-3397-induced FoxP3 expression was diminished when it was used in combination with mDexTA. Combination treatment also induced favorable systemic antitumor immunity in the spleen and lymph node. In conclusion, our findings provide insights into the synergy between mDexTA-based immunotherapy and PLX-3397 as the combination overcame the disadvantages associated with monotherapy and offer a therapeutic strategy for the treatment of solid tumors including melanoma.

LOCATOR: feature extraction and spatial analysis of the cancer tissue microenvironment using mass cytometry imaging technologies

Motivation

Recent advances in highly multiplexed imaging have provided unprecedented insights into the complex cellular organization of tissues, with many applications in translational medicine. However, downstream analyses of multiplexed imaging data face several technical limitations, and although some computational methods and bioinformatics tools are available, deciphering the complex spatial organization of cellular ecosystems remains a challenging problem.

Results

To mitigate this problem, we develop a novel computational tool, LOCATOR (anaLysis Of CAncer Tissue micrOenviRonment), for spatial analysis of cancer tissue microenvironments using data acquired from mass cytometry imaging technologies. LOCATOR introduces a graph-based representation of tissue images to describe features of the cellular organization and deploys downstream analysis and visualization utilities that can be used for data-driven patient-risk stratification. Our case studies using mass cytometry imaging data from two well-annotated breast cancer cohorts re-confirmed that the spatial organization of the tumour-immune microenvironment is strongly associated with the clinical outcome in breast cancer. In addition, we report interesting potential associations between the spatial organization of macrophages and patients' survival. Our work introduces an automated and versatile analysis tool for mass cytometry imaging data with many applications in future cancer research projects.

Availability and implementation

Datasets and codes of LOCATOR are publicly available at https://github.com/RezvanEhsani/LOCATOR.

Ponatinib delays the growth of solid tumours by remodelling immunosuppressive tumour microenvironment through the inhibition of induced PD-L1 expression

BACKGROUND

Therapeutic modalities including chemo, radiation, immunotherapy, etc. induce PD-L1 expression that facilitates the adaptive immune resistance to evade the antitumour immune response. IFN-γ and hypoxia are some of the crucial inducers of PD-L1 expression in tumour and systemic microenvironment which regulate the expression of PD-L1 via various factors including HIF-1α and MAPK signalling. Hence, inhibition of these factors is crucial to regulate the induced PD-L1 expression and to achieve a durable therapeutic outcome by averting the immunosuppression.

METHODS

B16-F10 melanoma, 4T1 breast carcinoma, and GL261 glioblastoma murine models were established to investigate the in vivo antitumour efficacy of Ponatinib. Western blot, immunohistochemistry, and ELISA were performed to determine the effect of Ponatinib on the immunomodulation of tumour microenvironment (TME). CTL assay and flow cytometry were such as p-MAPK, p-JNK, p-Erk, and cleaved caspase-3 carried out to evaluate the systemic immunity induced by Ponatinib. RNA sequencing, immunofluorescence and Western blot analysis were used to determine the mechanism of PD-L1 regulation by Ponatinib. Antitumour immunity induced by Ponatinib were compared with Dasatinib.

RESULTS

Here, Ponatinib treatment delayed the growth of tumours by inhibiting PD-L1 and modulating TME. It also downregulated the level of PD-L1 downstream signalling molecules. Ponatinib enhanced the CD8 T cell infiltration, regulated Th1/Th2 ratio and depleted tumour associated macrophages (TAMs) in TME. It induced a favourable systemic antitumour immunity by enhancing CD8 T cell population, tumour specific CTL activity, balancing the Th1/Th2 ratio and lowering PD-L1 expression. Ponatinib inhibited FoxP3 expression in tumour and spleen. RNA sequencing data revealed that Ponatinib treatment downregulated the genes related to transcription including HIF-1α. Further mechanistic studies showed that it inhibited the IFN-γ and hypoxia induced PD-L1 expression via regulating HIF-1α. Dasatinib was used as control to prove that Ponatinib induced antitumour immunity is via PD-L1 inhibition mediated T cell activation.

CONCLUSIONS

RNA sequencing data along with rigorous in vitro and in vivo studies revealed a novel molecular mechanism by which Ponatinib can inhibit the induced PD-L1 levels via regulating HIF-1α expression which leads to modulation of tumour microenvironment. Thus, our study provides a novel therapeutic insight of Ponatinib for the treatment of solid tumours where it can be used alone or in combination with other drugs which are known to induce PD-L1 expression and generate adaptive resistance.

Significance of tumor-infiltrating lymphocytes in tumor regression in breast cancer: A study in a tertiary care cancer center in South India

BACKGROUND

Tumor immunology plays a significant role in predicting tumor biology and how a tumor is going to respond to neoadjuvant chemotherapy (NACT). Tumor-infiltrating lymphocytes (TILs) are the easiest and by far the cheapest method of assessing tumor immunity. Many studies have suggested that TILs play an important role in tumor regression in breast cancer.

AIM

The aim of the current study was to determine significance of TILs in tumor regression in breast cancer.

MATERIALS AND METHODS

Patients with newly diagnosed and histologically proven breast cancer who were treated with both NACT and surgery in our institute were included in the study. TILs were assessed both before and after NACT, and were correlated with the relative amount of tumor regression and molecular subtypes based on the immunohistochemistry profile.

RESULTS

The study included 43 specimens of carcinoma breast in females. 42 cases were diagnosed with invasive carcinoma, no special type (NST), and one with lobular carcinoma. Pathological complete remission (pCR) was noted in 6 cases, partial remission (PRe) in 12 cases, and no response in 25 cases. TILs were noted before and after NACT in all cases and were correlated with other clinicopathological parameters.

CONCLUSION

The present study highlights that TILs play a vital role in tumor regression and can be included in routine reporting. It can provide an insight into tumor biology.

Advances in the application of computational pathology in diagnosis, immunomicroenvironment recognition, and immunotherapy evaluation of breast cancer: a narrative review

BACKGROUND

Breast cancer (BC) is a prevalent and highly lethal malignancy affecting women worldwide. Immunotherapy has emerged as a promising therapeutic strategy for BC, offering potential improvements in patient survival. Neoadjuvant therapy (NAT) has also gained significant clinical traction. With the advancement of computer technology, Artificial Intelligence (AI) has been increasingly applied in pathology research, expanding and redefining the scope of the field. This narrative review aims to provide a comprehensive overview of the current literature on the application of computational pathology in BC, specifically focusing on diagnosis, immune microenvironment recognition, and the evaluation of immunotherapy and NAT response.

METHODS

A thorough examination of relevant literature was conducted, focusing on studies investigating the role of computational pathology in BC diagnosis, immune microenvironment recognition, and immunotherapy and NAT assessment.

RESULTS

The application of computational pathology has shown significant potential in BC management. AI-based techniques enable improved diagnosis and classification of BC subtypes, enhance the identification and characterization of the immune microenvironment, and facilitate the evaluation of immunotherapy and NAT response. However, challenges related to data quality, standardization, and algorithm development still need to be addressed.

CONCLUSION

The integration of computational pathology and AI has transformative implications for BC patient care. By leveraging AI-based technologies, clinicians can make more informed decisions in diagnosis, treatment planning, and therapeutic response assessment. Future research should focus on refining AI algorithms, addressing technical challenges, and conducting large-scale clinical validation studies to facilitate the translation of computational pathology into routine clinical practice for BC patients.

The role of ion channels in the relationship between the immune system and cancer

The immune system is capable of identifying and eliminating cancer, a complicated illness marked by unchecked cellular proliferation. The significance of ion channels in the complex interaction between the immune system and cancer has been clarified by recent studies. Ion channels, which are proteins that control ion flow across cell membranes, have variety of physiological purposes, such as regulating immune cell activity and tumor development. Immune cell surfaces contain ion channels, which have been identified to control immune cell activation, motility, and effector activities. The regulation of immune responses against cancer cells has been linked to a number of ion channels, including potassium, calcium, and chloride channels. As an example, potassium channels are essential for regulating T cell activation and proliferation, which are vital for anti-tumor immunity. Calcium channels play a crucial role when immune cells produce cytotoxic chemicals in order to eliminate cancer cells. Chloride channels also affect immune cell infiltration and invasion into malignancies. Additionally, tumor cells' own expressed ion channels have an impact on their behavior and in the interaction with the immune system. The proliferation, resistance to apoptosis, and immune evasion of cancer cells may all be impacted by changes in ion channel expression and function. Ion channels may also affect the tumor microenvironment by controlling angiogenesis, inflammatory responses, and immune cell infiltration. Ion channel function in the interaction between the immune system and cancer has important implications for cancer treatment. A possible method to improve anti-tumor immune responses and stop tumor development is to target certain ion channels. Small compounds and antibodies are among the ion channel modulators under investigation as possible immunotherapeutics. The complex interaction between ion channels, the immune system, and cancer highlights the significance of these channels for tumor immunity. The development of novel therapeutic strategies for the treatment of cancer will be made possible by unraveling the processes by which ion channels control immune responses and tumor activity. Hence, the main driving idea of the present chapter is trying to understand the possible function of ion channels in the complex crosstalk between cancer and immunoresponse. To this aim, after giving a brief journey of ion channels throughout the history, a classification of the main ion channels involved in cancer disease will be discussed. Finally, the last paragraph will focus on more recently advancements in the use of biomaterials as therapeutic strategy for cancer treatment. The hope is that future research will take advantage of the promising combination of ion channels, immunomodulation and biomaterials filed to provide better solutions in the treatment of cancer disease.

Exploring the regulatory role of lncRNA in cancer immunity

Imbalanced immune homeostasis in cancer microenvironment is a hallmark of cancer. Increasing evidence demonstrated that long non-coding RNAs (lncRNAs) have emerged as key regulatory molecules in directly blocking the cancer immunity cycle, apart from activating negative regulatory pathways for restraining tumor immunity. lncRNAs reshape the tumor microenvironment via the recruitment and activation of innate and adaptive lymphoid cells. In this review, we summarized the versatile mechanisms of lncRNAs implicated in cancer immunity cycle, including the inhibition of antitumor T cell activation, blockade of effector T cell recruitment, disruption of T cell homing, recruitment of immunosuppressive cells, and inducing an imbalance between antitumor effector cells (cytotoxic T lymphocytes, M1 macrophages, and T helper type 1 cells) versus immunosuppressive cells (M2 macrophages, T helper type 2 cells, myeloid derived suppressor cells, and regulatory T cells) that infiltrate in the tumor. As such, we would highlight the potential of lncRNAs as novel targets for immunotherapy.

Implications of tumour heterogeneity on cancer evolution and therapy resistance: lessons from breast cancer

Tumour heterogeneity is pervasive amongst many cancers and leads to disease progression, and therapy resistance. In this review, using breast cancer as an exemplar, we focus on the recent advances in understanding the interplay between tumour cells and their microenvironment using single cell sequencing and digital spatial profiling technologies. Further, we discuss the utility of lineage tracing methodologies in pre-clinical models of breast cancer, and how these are being used to unravel new therapeutic vulnerabilities and reveal biomarkers of breast cancer progression. © 2023 The Pathological Society of Great Britain and Ireland.

Ribonuclease 1 Enhances Antitumor Immunity against Breast Cancer by Boosting T cell Activation

The secretory enzyme human ribonuclease 1 (RNase1) is involved in innate immunity and anti-inflammation, achieving host defense and anti-cancer effects; however, whether RNase1 contributes to adaptive immune response in the tumor microenvironment (TME) remains unclear. Here, we established a syngeneic immunocompetent mouse model in breast cancer and demonstrated that ectopic RNase1 expression significantly inhibited tumor progression. Overall changes in immunological profiles in the mouse tumors were analyzed by mass cytometry and showed that the RNase1-expressing tumor cells significantly induced CD4+ Th1 and Th17 cells and natural killer cells and reduced granulocytic myeloid-derived suppressor cells, supporting that RNase1 favors an antitumor TME. Specifically, RNase1 increased expression of T cell activation marker CD69 in a CD4+ T cell subset. Notably, analysis of cancer-killing potential revealed that T cell-mediated antitumor immunity was enhanced by RNase1, which further collaborated with an EGFR-CD3 bispecific antibody to protect against breast cancer cells across molecular subtypes. Our results uncover a tumor-suppressive role of RNase1 through adaptive immune response in breast cancer in vivo and in vitro, providing a potential treatment strategy of combining RNase1 with cancer immunotherapies for immunocompetent patients.

Combination of novel oncolytic herpesvirus with paclitaxel as an efficient strategy for breast cancer therapy

BACKGROUND

New strategies are needed to improve the treatment of patients with breast cancer (BC). Oncolytic virotherapy is a promising new tool for cancer treatment but still has a limited overall durable antitumor response. A novel replicable recombinant oncolytic herpes simplex virus type 1 called VG161 has been developed and has demonstrated antitumor effects in several cancers. Here, we explored the efficacy and the antitumor immune response of VG161 cotreatment with paclitaxel (PTX) which as a novel oncolytic viral immunotherapy for BC.

METHODS

The antitumor effect of VG161 and PTX was confirmed in a BC xenograft mouse model. The immunostimulatory pathways were tested by RNA-seq and the remodeling of tumor microenvironment was detected by Flow cytometry analysis or Immunohistochemistry. Pulmonary lesions were analyzed by the EMT6-Luc BC model.

RESULTS

In this report, we demonstrate that VG161 can significantly represses BC growth and elicit a robust antitumor immune response in a mouse model. The effect is amplified when combined with PTX treatment. The antitumor effect is associated with the infiltration of lymphoid cells, including CD4⁺ T cells, CD8⁺ T cells, and NK cells (expressing TNF and IFN-γ), and myeloid cells, including macrophages, myeloid-derived suppressor cells, and dendritic cell cells. Additionally, VG161 cotreatment with PTX showed a significant reduction in BC lung metastasis, which may result from the enhanced CD4⁺ and CD8⁺ T cell-mediated responses.

CONCLUSIONS

The combination of PTX and VG161 is effective for repressing BC growth by inducing proinflammatory changes in the tumor microenvironment and reducing BC pulmonary metastasis. These data will provide a new strategy and valuable insight for oncolytic virus therapy applications in primary solid or metastatic BC tumors.

Tumour Infiltrating Lymphocytes (TILs) and immune composition in breast cancer patients from Kenya: Spatial distributions and associations with risk factors and tumour characteristics

BACKGROUND

The immune landscape of breast cancer (BC) in patients from Sub Saharan Africa is understudied. Our aims were to describe the distribution of Tumour Infiltrating Lymphocytes (TILs) within the intratumoural stroma (sTILs) and the leading/invasive edge stroma (LE-TILs), and to evaluate TILs across BC subtypes with established risk factors and clinical characteristics in Kenyan women.

METHODS

Visual quantification of sTILs and LE-TILs were performed on Haematoxylin and eosin -stained pathologically confirmed BC cases based on the International TIL working group guidelines. Tissue Microarrays were constructed and stained with immunohistochemistry (IHC) for CD3, CD4, CD8, CD68, CD20, and FOXP3. Linear and logistic regression models were used to assess associations between risk factors and tumour features with IHC markers and total TILs, after adjusting for other covariates.

RESULTS

A total of 226 invasive BC cases were included. Overall, LE-TIL (mean = 27.9, SD = 24.5) proportions were significantly higher than sTIL (mean = 13.5, SD = 15.8). Both sTILs and LE- TILs were predominantly composed of CD3, CD8, and CD68. We found higher TILs to be associated with high KI67/high grade and aggressive tumour subtypes, although these associations varied by TIL locations. Older age at menarche (≥ 15 vs. < 15 years) was associated with higher CD3 (OR: 2.06, 95%CI:1.26-3.37), but only for the intra-tumour stroma.

CONCLUSION

The TIL enrichment in more aggressive BCs is similar to previously published data in other populations. The distinct associations of sTIL/LE-TIL measures with most examined factors highlight the importance of spatial TIL evaluations in future studies.

Early variation of inflammatory indexes refines prognostic prediction in patients with hepatocellular carcinoma under systemic treatment

Prognostic markers in advanced hepatocellular carcinoma (HCC) are relevant for clinical decisions. Variations in inflammatory indexes, such as neutrophil-to-lymphocyte ratio (NLR) or platelet-to-lymphocyte ratio (PLR), may correlate with outcomes. In the present study, it was aimed to assess the prognostic role of inflammation indexes in patients with HCC and the evolutionary behavior of these variables within the first month of treatment in a cohort of patients treated with sorafenib from 2009-2021. Subgroups were divided based on the median of each variable ('low' or 'high)'. Survival was estimated using the Kaplan-Meier method. Hazard Ratio (HR) with 95% confidence interval (CI) were estimated using Cox regression models. A total of 373 patients were included, most Child-Pugh-A (83.1%) and BCLC-C (74%). Child-Pugh-A (P=0.011), performance status 0 (P<0.001), no ascites (P<0.001) and NLR<2.6 (P<0.001) were independently associated with improved survival. Baseline PLR was not correlated with survival (P=0.137). Patients who maintained low NLR at baseline and at 1 month (reference subgroup) had improved survival (18.6 months, 95% CI:15.4-22.0) compared with the subgroup that maintained high NLR at baseline and at 1 month (4.2 months, 95% CI:3.6-5.9), with HR: 3.80 (95% CI: 2.89-4.96). The subgroup with low NLR at baseline and high NLR at 1 month had a worse prognosis compared with the reference group (HR:1.4, 95% CI: 1.1-2.0), whereas the subgroup with high NLR at baseline and low at 1 month had similar outcome (HR:1.2, 95% CI: 0.8-1.6). It was concluded that evolutionary variation of NLR has a prognostic role in HCC patients under systemic therapy. This finding suggested that systemic inflammation and early modulation of the immune environment during treatment may correlate with outcomes.

The molecular landscape of breast mucoepidermoid carcinoma

Mucoepidermoid carcinoma (MEC) of the breast is an extremely rare salivary gland-type tumor characterized by epidermoid, basaloid, intermediate, and/or mucinous cells arranged in solid and cystic patterns. Despite their triple-negative phenotype, breast MECs are generally considered low-risk malignancies but their biology is largely unexplored; therefore, guidelines for clinical management are lacking. Here, we sought to characterize the molecular landscape of breast MECs. Thirteen cases were histologically reviewed, characterized for tumor-infiltrating lymphocytes (TILs), and were subjected to immunohistochemistry for programmed death-ligand 1 (PD-L1, clone 22C3), EGFR, and amphiregulin (AREG). Rearrangements in MAML2 and EWSR1 were investigated by fluorescent in situ hybridization. Targeted next-generation sequencing of 161 genes was performed on eight cases. Most MECs had low histological grade (n = 10, 77%), with the presence of TILs (n = 9/12; 75%) and PD-L1 combined positive score ranging from 10 to 20 (n = 4/6; 67%). All cases showed EGFR and AREG overexpression and were fusion negative. Enrichment of genetic alterations was observed in PI3K/AKT/mTOR and cell cycle regulation pathways, while only one case harbored TP53 mutations. This is the first study providing extensive molecular data on breast MECs and the largest collection of cases available to date in the literature. Breast MECs lack TP53 mutations found in high-grade forms of triple-negative breast cancers and MAML2 or EWSR1 rearrangements pathognomonic of salivary MECs. Triple-negativity and PD-L1 positivity suggest a window of opportunity for immunotherapy in these patients. The EGFR/AREG axis activation, coupled with the mutational patterns in PI3K/AKT/mTOR and cell cycle pathways warrants caution in considering MECs as low-risk neoplasms.

Breast Cancer Survival Outcomes and Tumor-Associated Macrophage Markers: A Systematic Review and Meta-Analysis

INTRODUCTION

Tumor-associated macrophages (TAMs) in breast cancer are associated with a poor prognosis. Early studies of TAMs were largely limited to the pan-macrophage marker CD68, however, more recently, an increasing number of studies have used CD163, a marker expressed by alternatively activated M2 macrophages and TAM subsets. We hypothesized that CD163-positive (CD163+) TAMs would be a better predictor of survival outcomes in breast cancer compared to CD68+  TAMs.

METHODS

We performed a systematic literature search of trials (from 1900 to August 2020) reporting overall survival (OS) or progression-free survival (PFS), breast cancer-specific survival (BCSS), TAM phenotype, and density. Thirty-two studies with 8446 patients were included. Meta-analyses were carried out on hazard ratios (HRs) for survival outcomes of breast cancer patients with a high density of TAMs (CD68+ and/or CD163+) compared to a low density of TAMs.

RESULTS

A high density of TAMs (CD68+ and/or CD163+) was associated with decreased OS (HR 1.69, 95% CI 1.37-2.07) and reduced PFS (HR 1.64; 95% CI 1.35-1.99). Subgrouping by CD marker type showed a lower OS for high density of CD163+ TAMs (HR 2.24; 95% CI 1.71-2.92) compared to a high density of CD68+  TAMs (HR 1.5; 95% CI 1.12-2). A high density of TAMs (CD68+  and/or CD163+) in triple-negative breast cancer (TNBC) cases was associated with lower OS (HR 2.81, 95% CI 1.35-5.84).

CONCLUSION

Compared to CD68+  TAMs, a high density of CD163+ TAMs that express a similar phenotype to M2 macrophages are a better predictor of poor survival outcomes in breast cancer.

Application of individualized multimodal radiotherapy combined with immunotherapy in metastatic tumors

Radiotherapy is one of the mainstays of cancer treatment. More than half of cancer patients receive radiation therapy. In addition to the well-known direct tumoricidal effect, radiotherapy has immunomodulatory properties. When combined with immunotherapy, radiotherapy, especially high-dose radiotherapy (HDRT), exert superior systemic effects on distal and unirradiated tumors, which is called abscopal effect. However, these effects are not always effective for cancer patients. Therefore, many studies have focused on exploring the optimized radiotherapy regimens to further enhance the antitumor immunity of HDRT and reduce its immunosuppressive effect. Several studies have shown that low-dose radiotherapy (LDRT) can effectively reprogram the tumor microenvironment, thereby potentially overcoming the immunosuppressive stroma induced by HDRT. However, bridging the gap between preclinical commitment and effective clinical delivery is challenging. In this review, we summarized the existing studies supporting the combined use of HDRT and LDRT to synergistically enhance antitumor immunity, and provided ideas for the individualized clinical application of multimodal radiotherapy (HDRT+LDRT) combined with immunotherapy.

The relevance between hypoxia-dependent spatial transcriptomics and the prognosis and efficacy of immunotherapy in claudin-low breast cancer

Introduction

Hypoxia is an important characteristic of solid tumors. However, spatial transcriptomics (ST) of hypoxia-associated heterogeneity is not clear.

Methods

This study integrated Spatial Transcriptomics (ST) with immunofluorescence to demonstrate their spatial distribution in human claudin-low breast cancer MDA-MB-231 engraft. ST spots were clustered with differentially expression genes. The data were combined with hypoxia-specific marker and angiogenesis marker-labeled serial sections to indicate the spatial distribution of hypoxia and hypoxia-inducted transcriptional profile. Moreover, marker genes, cluster-specific hypoxia genes, and their co-essential relationship were identified and mapped in every clusters. The clinicopathological association of marker genes of hypoxia-dependent spatial clusters was explored in 1904 breast cancers from METABRIC database.

Results

The tumor from center to periphery were enriched into five hypoxia-dependent subgroups with differentially expressed genes, which were matched to necrosis, necrosis periphery, hypoxic tumor, adaptive survival tumor, and invasive tumor, respectively. Different subgroups demonstrated distinct hypoxia condition and spatial heterogeneity in biological behavior and signaling pathways. Cox regression analysis showed that the invasive tumor (cluster 0) and hypoxic tumor (cluster 6) score could be served as independent prognostic factors in claudin-low patients. KM analysis indicated that high invasive tumor (cluster 0) and hypoxic tumor (cluster 6) score was associated with poor prognoses of claudin-low patients. Further analysis showed that hypoxia-induced immune checkpoints, such as CD276 and NRP1, upregulation in invasive tumor to block infiltration and activation of B cells and CD8+ T cells to change tumor immune microenvironment.

Discussion

This study reveals hypoxia-dependent spatial heterogeneity in claudin-low breast cancer and highlights its potential value as a predictive biomarker of clinical outcomes and immunotherapy response. The molecules found in this study also provided potential molecular mechanisms and therapeutic targets for subsequent studies.

Transcriptomics indicate nuclear division and cell adhesion not recapitulated in MCF7 and MCF10A compared to luminal A breast tumours

Breast cancer (BC) cell lines are useful experimental models to understand cancer biology. Yet, their relevance to modelling cancer remains unclear. To better understand the tumour-modelling efficacy of cell lines, we performed RNA-seq analyses on a combined dataset of 2D and 3D cultures of tumourigenic MCF7 and non-tumourigenic MCF10A. To our knowledge, this was the first RNA-seq dataset comprising of 2D and 3D cultures of MCF7 and MCF10A within the same experiment, which facilitates the elucidation of differences between MCF7 and MCF10A across culture types. We compared the genes and gene sets distinguishing MCF7 from MCF10A against separate RNA-seq analyses of clinical luminal A (LumA) and normal samples from the TCGA-BRCA dataset. Among the 1031 cancer-related genes distinguishing LumA from normal samples, only 5.1% and 15.7% of these genes also distinguished MCF7 from MCF10A in 2D and 3D cultures respectively, suggesting that different genes drive cancer-related differences in cell lines compared to clinical BC. Unlike LumA tumours which showed increased nuclear division-related gene expression compared to normal tissue, nuclear division-related gene expression in MCF7 was similar to MCF10A. Moreover, although LumA tumours had similar cell adhesion-related gene expression compared to normal tissues, MCF7 showed reduced cell adhesion-related gene expression compared to MCF10A. These findings suggest that MCF7 and MCF10A cell lines were limited in their ability to model cancer-related processes in clinical LumA tumours.

DNA barcoding reveals ongoing immunoediting of clonal cancer populations during metastatic progression and immunotherapy response

Cancers evade the immune system through the process of cancer immunoediting. While immune checkpoint inhibitors are effective for reactivating tumour immunity in some cancer types, many other solid cancers, including breast cancer, remain largely non-responsive. Understanding how non-responsive cancers evade immunity and whether this occurs at the clonal level will improve immunotherapeutic design. Here we use DNA barcoding to track murine mammary cancer cell clones during immunoediting and determine clonal transcriptional profiles that allow immune evasion following anti-PD1 plus anti-CTLA4 immunotherapy. Clonal diversity is significantly restricted by immunotherapy treatment in both primary tumours and metastases, demonstrating selection for pre-existing breast cancer cell populations and ongoing immunoediting during metastasis and treatment. Immunotherapy resistant clones express a common gene signature associated with poor survival of basal-like breast cancer patient cohorts. At least one of these genes has an existing small molecule that can potentially be used to improve immunotherapy response.

An update on the use of cryoablation and immunotherapy for breast cancer

The use of cryoablation, a minimally-invasive image-guided technique to target and kill cancer cells, continues to gain traction within the medical field and with patients. This includes the use of cryoablation for the treatment of small breast cancers and focal sites of metastatic disease. In comparison to open surgical approaches, length of hospital stay and recovery time are decreased with the use of cryoablation. Research studies have also found that cryoablation may actually enhance tumor susceptibility to immunotherapy agents. Immunotherapy enhances a person's own immune system to identify and attack cancer cells. It is proposed that after cryoablation there is increased expression of tumor specific antigens which the body can recognize as foreign invaders and with the combination of immunotherapy, result in an even more robust and efficient attack on the cancer cells. In this review we aim to highlight some of the recent advances in cryoablation which support the potential for cryoablation to induce these tumor-specific immune responses and thus supporting the use of combining cryoablation and immunotherapy for the treatment of breast cancer.

Microfibrillar-associated protein 2 is a prognostic marker that correlates with the immune microenvironment in glioma

Aims: microfibrillar-associated protein 2 (MFAP2), a component of the extracellular matrix, plays key roles in regulating growth factor signal transduction and various malignant tumors. However, the clinicopathological features of microfibrillar-associated protein 2 in gliomas have not been elucidated to date.

Methods: TCGA and CGGA databases were used to study the expression of microfibrillar-associated protein 2 in glioma and its relationship with clinicopathological features of patients with glioma. Western blotting was performed to detect the expression of microfibrillar-associated protein 2 protein in tissue samples from glioma patients. Gene set enrichment analysis (GSEA) was applied to detect biological processes and signal pathways related to microfibrillar-associated protein 2. Single-sample gene set enrichment analysis, TIMER 2.0, and TISIDB databases were used to evaluate the role of microfibrillar-associated protein 2 in tumor immune characteristics. The prognostic role of microfibrillar-associated protein 2 in glioma was analyzed using the Kaplan-Meier method and Cox regression. Survival data were used to establish a nomogram prediction model.

Results: microfibrillar-associated protein 2 expression was significantly elevated in gliomas. receiver operating characteristic analysis revealed good discrimination of microfibrillar-associated protein 2 between glioma and normal tissues. High expression of microfibrillar-associated protein 2 was associated with malignant phenotypes, such as histological type. Based on gene set enrichment analysis, we identified pathways associated with high microfibrillar-associated protein 2 expression. High microfibrillar-associated protein 2 expression was related to the infiltration of tumor immune cells, including Th2 cells and macrophages, and correlated with key markers of T-cell exhaustion. Based on the TISIDB database, microfibrillar-associated protein 2 was observed to be associated with chemokines, chemokine receptors, and multiple immunoinhibitors in glioma. Kaplan–Meier survival analyses revealed that high microfibrillar-associated protein 2 expression predicted poor overall survival, DSS, and PFS in patients with glioma. By combining microfibrillar-associated protein 2 and other prognostic factors, a nomogram prognostic prediction model was constructed, which demonstrated an ideal prediction effect.

Conclusion: microfibrillar-associated protein 2 is a potential prognostic marker that plays a key role in glioma development given its association with malignant phenotypes, cancer-related pathways and tumor immunity.

Evaluation and comparison of intratumoural and intrastromal infiltrating lymphocytes with clinicopathological features in breast carcinoma patients who have received neoadjuvant chemotherapy - A cross-sectional study

Background

The microenvironment of breast cancer plays a significant role in determining the prognosis of the disease. With the shifting paradigm on the predictive factors post-Neoadjuvant Chemotherapy (NAC), it was sought out that Tumour infiltrating lymphocytes (TILs) are of valuable use for the same. Yet, the delineation of the two types - Intrastromal and Intratumoural has seldom been facilitated. This study, therefore, aimed to evaluate, analyse and compare the two - to gauge the importance of the treatment outcome and clinicopathological features.

Materials and methods

180 breast cancer patients were included in this study who underwent NAC, and their post-surgically resected tumour specimens were sectioned and stained using routine Haematoxylin and Eosin techniques. The evaluation of TILs in the stroma and tumour was done based on the standardised guidelines.

Results

Out of the 180 patients, 55 (i.e. 30.56%) displayed pathological complete resolution (pCR). Furthermore, Intratumoural TILs had a slight association with the pCR (p = 0.0335) whereas Intrastromal TILs had a significantly large association with pCR (p < 0.0001) dependent on the lymphocytic response. Backward regression revealed that - the age at operation, pCR, lymph node involvement and menopause highly contributed to predicting 68.2% of the total cases correctly with a sensitivity of 93.0% and specificity of 24.6% for Intratumoral TILs. Age at operation, pCR, lymph node involvement and tumour emboli highly contributed to predicting 71.5% of the total cases correctly with sensitivity of 71.6% and specificity of 71.4% for Intrastromal TILs.

Conclusion

TILs and the prediction of NAC and pCR should be made standardised and reproducible so that they can be universally available to all patients with breast cancer. Through this study, further avenues of research have opened up for their relations with clinicopathological features mainly age at operation and menopausal status.

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IT & IS TILs play a varied role in the prediction of NAC and pCR.

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Post-NAC 55 patients (i.e. 30.56%) out of 180 displayed pCR.

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Age at operation, pCR, lymph node involvement and menopause highly contributed to predict IT TILs.

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Age at operation, pCR, lymph node involvement and tumour emboli highly contributed to predict IS TILs.

•

Analysis of TILs can be a reliable method in the treatment response and immunogenicity of breast tumours.

NKG7 Enhances CD8+ T Cell Synapse Efficiency to Limit Inflammation

Cytotoxic lymphocytes are essential for anti-tumor immunity, and for effective responses to cancer immunotherapy. Natural killer cell granule protein 7 (NKG7) is expressed at high levels in cytotoxic lymphocytes infiltrating tumors from patients treated with immunotherapy, but until recently, the role of this protein in cytotoxic lymphocyte function was largely unknown. Unexpectedly, we found that highly CD8+ T cell-immunogenic murine colon carcinoma (MC38-OVA) tumors grew at an equal rate in Nkg7^+/+ and Nkg7^-/- littermate mice, suggesting NKG7 may not be necessary for effective CD8+ T cell anti-tumor activity. Mechanistically, we found that deletion of NKG7 reduces the ability of CD8+ T cells to degranulate and kill target cells in vitro. However, as a result of inefficient cytotoxic activity, NKG7 deficient T cells form a prolonged immune synapse with tumor cells, resulting in increased secretion of inflammatory cytokines, including tumor necrosis factor alpha (TNF). By deleting the TNF receptor, TNFR1, from MC38-OVA tumors, we demonstrate that this hyper-secretion of TNF compensates for reduced synapse-mediated cytotoxic activity against MC38-OVA tumors in vivo, via increased TNF-mediated tumor cell death. Taken together, our results demonstrate that NKG7 enhances CD8+ T cell immune synapse efficiency, which may serve as a mechanism to accelerate direct cytotoxicity and limit potentially harmful inflammatory responses.

Promoting Best Practice in Cancer Care in Sub Saharan Africa

Promoting best practice in the management of a cancer patient is rooted in the application of new knowledge derived through various sources including population science, laboratory advances, and translational research. Ultimately, the impact of these advances depends on their application at the patient's bedside. A close collaboration between the oncologist and the pathologist is critical in underwriting progress in the management of the cancer patient. Recent advancements have shown that more granular characteristics of the tumor and the microenvironment are defining determinants when it comes to disease course and overall outcome. Whereas, histologic features and basic immunohistochemical characterization were previously adequate to define the tumor and establish treatment recommendation, the growing capability of the pathologist to provide molecular characterization of the tumor and its microenvironment, as well as, the availability of novel therapeutic agents have revolutionized cancer treatment paradigms and improved patient-outcomes and survival. While such capacity and capability appear readily available in most developed high-income countries (HIC), it will take a concerted and collaborative effort of all stakeholders to pave the way in the same stride in the low and middle-income countries (LMIC), which bear a disproportionate burden of human illness and cancers. Patients in the LMIC present with disease at advanced stage and often display characteristics unlike those encountered in the developed world. To keep stride and avoid the disenfranchisement of patients in the LMIC will require greater participation of LMIC patients on the global clinical trial platform, and a more equitable and affordable sharing of diagnostic and therapeutic capabilities between the developed and developing world. Key to the success of this progress and improvement of patient outcomes in the developing world is the close collaboration between the oncologist and the pathologist in this new era of precision and personalized medicine.

Pathological Diagnosis, Work-Up and Reporting of Breast Cancer 1st Central-Eastern European Professional Consensus Statement on Breast Cancer

This text is based on the recommendations accepted by the 4th Hungarian Consensus Conference on Breast Cancer, modified on the basis of the international consultation and conference within the frames of the Central-Eastern European Academy of Oncology. The recommendations cover non-operative, intraoperative and postoperative diagnostics, determination of prognostic and predictive markers and the content of cytology and histology reports. Furthermore, they address some specific issues such as the current status of multigene molecular markers, the role of pathologists in clinical trials and prerequisites for their involvement, and some remarks about the future.

Spatially resolved transcriptomics provide a new method for cancer research

A major feature of cancer is the heterogeneity, both intratumoral and intertumoral. Traditional single-cell techniques have given us a comprehensive understanding of the biological characteristics of individual tumor cells, but the lack of spatial context of the transcriptome has limited the study of cell-to-cell interaction patterns and hindered further exploration of tumor heterogeneity. In recent years, the advent of spatially resolved transcriptomics (SRT) technology has made possible the multidimensional analysis of the tumor microenvironment in the context of intact tissues. Different SRT methods are applicable to different working ranges due to different working principles. In this paper, we review the advantages and disadvantages of various current SRT methods and the overall idea of applying these techniques to oncology studies, hoping to help researchers find breakthroughs. Finally, we discussed the future direction of SRT technology, and deeper investigation into the complex mechanisms of tumor development from different perspectives through multi-omics fusion, paving the way for precisely targeted tumor therapy.

Combination of oxaliplatin and POM-1 by nanoliposomes to reprogram the tumor immune microenvironment

Some chemotherapy can damage tumor cells, releasing damage-related molecular patterns including ATP to improve immunological recognition against the tumor by immunogenic cell death (ICD). However, the immune-stimulating ATP may be rapidly degraded into immunosuppressive adenosine by highly expressed CD39 and CD73 in the tumor microenvironment, which leads to immune escape. Based on the above paradox, a liposome nanoplatform combined with ICD inducer (oxaliplatin) and CD39 inhibitor (POM-1) is designed for immunochemotherapy. The liposomes efficiently load the phospholipid-like oxaliplatin prodrug, and the cationic charged surface could adsorb POM-1. Rationally designed DSPE-PEG_n-pep, on the one hand, could cover and hide POM-1 to avoid systematic toxicity and, on the other, achieve a response and charge reversal to favor POM-1 shedding and tumor deep penetration. This combination maximizes the ICD effect, and takes two-pronged advantage of stimulating the immune response and relieving immune suppression. The designed POL can effectively inhibit the growth of in situ, lung metastasis and postoperative recurrence melanoma model and form long-term immune memory. With the powerful clinical transformation potential of nanoliposome platforms, this new synergistic strategy is expected to enhance anticancer effects safely and effectively.

Expression and clinical prognostic value of CYB561 in breast cancer

PURPOSE

The expression of cytochrome B561 (CYB561) and its role in breast cancer (BC) prognosis remain unclear. We analyzed the differential expression and prognostic value of CYB561 using online databases and a clinical cohort through bioinformatics and immunohistochemistry.

METHODS

The differential expression of CYB561 and its association with BC were analyzed using the tumor immune estimation resource (TIMER), gene expression profiling interaction analysis2 (GEPIA2), Human Protein Atlas, Cancer Cell Line Encyclopedia, and Kaplan-Meier Plotter website. Important pathways of CYB561 enrichment were explored using gene set enrichment analysis. Immunohistochemistry detected CYB561 expression in normal breast, breast hyperplasia, ductal carcinoma in situ (DCIS), para-cancer, and invasive BC groups. Association between CYB561 expression and BC prognosis was analyzed using Kaplan-Meier and Cox regression analyses.

RESULTS

CYB561 mRNA expression was higher in GEPIA and TIMER BC patients than in para-cancer tissues. CYB561 was expressed in the glandular epithelium and myoepithelium, with positive localization in the cytoplasm and cell membrane. CYB561 protein expression significantly differed among the groups. CYB561 expression was correlated with ERBB2/HER2 and infiltrating CD4+ T cells in GEPIA and TIMER BC patients and associated with HER2 status, histological grade, and molecular subtypes in the clinical cohort but not related to tumor-infiltrating lymphocytes. CYB561 mRNA overexpression predicted reduced recurrence-free survival and overall survival in BC. Patients with CYB561 expression had significantly reduced overall survival and increased risk of death.

CONCLUSION

CYB561 can serve as an effective clinical prognostic biomarker for BC.

Combining Radiotherapy and Immunotherapy in Metastatic Breast Cancer: Current Status and Future Directions

The role of radiotherapy and immunotherapy with immune checkpoint inhibitors (ICI) is of emerging interest in many solid tumours, including breast cancer. There is increasing evidence that the host's immune system plays an important role in influencing the response to treatment and prognosis in breast cancer. Several pre-clinical studies and clinical trials have reported on the 'abscopal effect-regression of distant untreated tumour sites, mediated by an immunological response following ionizing radiation to a targeted tumour site. Stereotactic Ablative Body Radiotherapy (SABR) is a non-invasive technique used to augment various immune responses with an ablative tumoricidal dose when compared to conventional radiotherapy. SABR is characterized by typically 1-5 precision radiotherapy treatments that simultaneously deliver a high dose, whilst sparing normal tissues. Following SABR, there is evidence of systemic immune activation in patients with increased PD1 expression on CD8+ and CD4+ T cells. Studies continue to focus on metastatic triple-negative disease, a highly immunogenic subtype of breast cancer with poor prognosis. In this review, we discuss the immunological effect of SABR, alone and in combination with immunotherapy, and the importance of dose and fractionation. We also propose future strategies for treating oligometastatic disease, where this approach may be most useful for producing durable responses.

Tumor Cell-Autonomous Pro-Metastatic Activities of PD-L1 in Human Breast Cancer Are Mediated by PD-L1-S283 and Chemokine Axes

Simple Summary

Triple-negative breast cancer (TNBC) is an aggressive disease that responds in a limited manner to immune checkpoint blockades targeting the PD-L1/PD-1 axis, suggesting that PD-L1 potentiates TNBC progression via pathways not related to immune suppression. We demonstrated that, in human breast cancer cells, PD-L1 expression increased in a cell-autonomous manner tumor cell growth, invasion and release of pro-metastatic factors; these activities were elevated by exposure to PD-1 and were markedly impaired in S283-mutated PD-L1-expressing cells. Invasion of WT-PD-L1-expressing TNBC cells depended on autocrine chemokine circuits, involving CXCR1/2, CCR2, CCR5 and their ligands. In T cell-deficient mice, WT-PD-L1 exhibited increased tumor growth and metastasis by TNBC cells, whereas S283A-PD-L1-expressing cells showed a very poor tumorigenic and metastatic profile. These findings on cell-autonomous and PD-1-induced pro-metastatic activities of PD-L1 in cancer cells suggest that treatments targeting PD-L1 could improve the efficacy of immune-targeting checkpoint inhibitors, e.g., anti-PD-1 or anti-CTLA-4 in TNBC.

Abstract

Therapies targeting the PD-L1/PD-1 axis have recently been introduced to triple-negative breast cancer (TNBC) with limited efficacy, suggesting that this axis promotes tumor progression through mechanisms other than immune suppression. Here, we over-expressed WT-PD-L1 in human TNBC cells (express endogenous PD-L1) and in luminal-A breast cancer cells (no endogenous PD-L1 expression) and demonstrated that cell-autonomous PD-L1 activities lead to increased tumor cell growth, invasion and release of pro-metastatic factors (CXCL8, sICAM-1, GM-CSF). These activities were promoted by PD-1 and were inhibited by mutating S283 in PD-L1. Invasion of WT-PD-L1-cells required signaling by chemokine receptors CXCR1/2, CCR2 and CCR5 through autocrine circuits involving CXCL8, CCL2 and CCL5. Studies with T cell-deficient mice demonstrated that cell-autonomous WT-PD-L1 activities in TNBC cells increased tumor growth and metastasis compared to knock-out (KO)-PD-L1-cells, whereas S283A-PD-L1-expressing cells had minimal ability to form tumors and did not metastasize. Overall, our findings reveal autonomous and PD-1-induced tumor-promoting activities of PD-L1 that depend on S283 and on chemokine circuits. These results suggest that TNBC patients whose tumors express PD-L1 could benefit from therapies that prevent immune suppression by targeting PD-1/CTLA-4, alongside with antibodies to PD-L1, which would allow maximal impact by mainly targeting the cancer cells.

Tumor-infiltrating lymphocytes in breast FNA biopsy cytology: a predictor of tumor-infiltrating lymphocytes in histologic evaluation

BACKGROUND

Tumor-infiltrating lymphocytes (TILs) are associated with various clinicopathological features. Using cytologic specimens for assessing TILs remains to be established. This retrospective study aimed to establish a practical method to assess TILs in cytologic samples.

METHODS

The authors found 1101 breast fine-needle aspiration biopsy (FNAB) cytology samples in their hospital, and 214 of them met the inclusion criteria. The TILs score was evaluated using histologic slides, and breast cancers were divided into 2 groups: low- (<60%) and high-TILs (≥60%). Training and validation tests composed of 50 breast cancer samples each were constructed. A cytologic TILs (cTILs) score was introduced to evaluate lymphocytes in FNAB cytology and it was compared with histologically evaluated TILs. The cTILs score was calculated by subtracting the number of neutrophils from the number of lymphocytes surrounding the tumor cells.

RESULTS

In the training test, a 2-tier system with low- and high-TILs groups showed a large area under the curve (AUC) (0.943; 95% confidence interval [CI], 0.84-0.99). A cTILs score cutoff value of >8 had 87.5% sensitivity and 90.5% specificity. In the validation test, the AUC was 0.79 (95% CI, 0.6-0.93) whereas sensitivity and specificity were 57% and 89.5%, respectively. When small tumors <0.5 cm were excluded, the AUC improved to 0.93 (95% CI, 0.83-1.0), and sensitivity and specificity were 80% and 88.5%, respectively.

CONCLUSIONS

The cTILs scoring system had acceptable reproducibility and concordance with TILs on histologic samples for tumors ≥0.5 cm. Cytologic evaluation can potentially substitute for histologic evaluation of TILs.

Bedside formulation of a personalized multi-neoantigen vaccine against mammary carcinoma

Background

Harnessing the immune system to purposely recognize and destroy tumors represents a significant breakthrough in clinical oncology. Non-synonymous mutations (neoantigenic peptides) were identified as powerful cancer targets. This knowledge can be exploited for further improvements of active immunotherapies, including cancer vaccines, as T cells specific for neoantigens are not attenuated by immune tolerance mechanism and do not harm healthy tissues. The current study aimed at developing an optimized multitarget vaccine using short or long neoantigenic peptides utilizing virus-like particles (VLPs) as an efficient vaccine platform.

Methods

Mutations of murine mammary carcinoma cells were identified by integrating mass spectrometry-based immunopeptidomics and whole exome sequencing. Neoantigenic peptides were synthesized and covalently linked to virus-like nanoparticles using a Cu-free click chemistry method for easy preparation of vaccines against mouse mammary carcinoma.

Results

As compared with short peptides, vaccination with long peptides was superior in the generation of neoantigen-specific CD4⁺ and CD8⁺ T cells, which readily produced interferon gamma (IFN-γ) and tumor-necrosis factor α (TNF-α). The resulting anti-tumor effect was associated with favorable immune re-polarization in the tumor microenvironment through reduction of myeloid-derived suppressor cells. Vaccination with long neoantigenic peptides also decreased post-surgical tumor recurrence and metastases, and prolonged mouse survival, despite the tumor’s low mutational burden.

Conclusion

Integrating mass spectrometry-based immunopeptidomics and whole exome sequencing is an efficient approach for identifying neoantigenic peptides. Our multitarget VLP-based vaccine shows a promising anti-tumor effect in an aggressive murine mammary carcinoma model. Future clinical application using this strategy is readily feasible and practical, as click chemistry coupling of personalized synthetic peptides to the nanoparticles can be done at the bedside directly before injection.

Antigen presentation and interferon signatures in B cells driven by localized ablative cancer immunotherapy correlate with extended survival

Rationale: B cells have emerged as key regulators in protective cancer immunity. However, the activation pathways induced in B cells during effective immunotherapy are not well understood. Methods: We used a novel localized ablative immunotherapy (LAIT), combining photothermal therapy (PTT) with intra-tumor delivery of the immunostimulant N-dihydrogalactochitosan (GC), to treat mice bearing mouse mammary tumor virus-polyoma middle tumor-antigen (MMTV-PyMT). We used single-cell RNA sequencing to compare the transcriptional changes induced by PTT, GC and PTT+GC in B cells within the tumor microenvironment (TME). Results: LAIT significantly increased survival in the tumor-bearing mice, compared to the treatment by PTT and GC alone. We found that PTT, GC and PTT+GC increased the proportion of tumor-infiltrating B cells and induced gene expression signatures associated with B cell activation. Both GC and PTT+GC elevated gene expression associated with antigen presentation, whereas GC elevated transcripts that regulate B cell activation and GTPase function and PTT+GC induced interferon response genes. Trajectory analysis, where B cells were organized according to pseudotime progression, revealed that both GC and PTT+GC induced the differentiation of B cells from a resting state towards an effector phenotype. The analyses confirmed upregulated interferon signatures in the differentiated tumor-infiltrating B cells following treatment by PTT+GC but not by GC. We also observed that breast cancer patients had significantly longer survival time if they had elevated expression of genes in B cells that were induced by PTT+GC therapy in the mouse tumors. Conclusion: Our findings show that the combination of local ablation and local application of immunostimulant initiates the activation of interferon signatures and antigen-presentation in B cells which is associated with positive clinical outcomes for breast cancer. These findings broaden our understanding of LAIT's regulatory roles in remodeling TME and shed light on the potentials of B cell activation in clinical applications.

Integrative analysis of prognostic value and immune infiltration of spindle and kinetochore-associated family members in breast cancer

Spindle and kinetochore associated (SKA) complex subunit, which maintains the stability of mitotic metaphase, with emerging research implying its effect as a carcinogenic regulator in cancer. However, its potential role in BC has not been fully elucidated. ONCOMINE, UALCAN, GEPIA, Kaplan-Meier Plotter, cBioPortal and TIMER databases were performed to analyze the expression, prognosis, mutation, immune infiltration and potential biological mechanisms of SKA1/2/3 in BC. Our results showed that SKA1/2/3 expression was upregulated in BC. Survival analysis reveals that SKA3 overexpression was associated with poor overall survival (OS), relapse-free survival (RFS), post-progression survival (PPS) and distant metastasis-free survival (DMFS). SKA1 overexpression was associated with poor OS, RFS and DMFS while SKA2 overexpression was only associated with RFS and DMFS. Notably, the results implied that SKA1 has a good prognostic value in HER2-positive BC. Besides, the genetic alterations of SKA were investigated and the altered group correlated with shorter progress-free survival (PFS) and disease-specific survival (DSS). GO and KEGG analysis showed that SKA1/2/3 were implicated in regulating cell cycle, p53 signaling pathway and DNA replication. The 10 Hub genes in the protein network were upregulated in BC and related to poorer prognosis. Additionally, SKA1/2/3 expression was negatively correlated with infiltration of various immune cells with antitumor effects, whereas positively correlated with the expression of immune checkpoints molecules. Further experiments revealed that SKA1/2/3 silencing markedly impeded the proliferation and migration of BC cells. Herein, our study firmly shows that SKA genes may serve as a promising therapeutic target for patients with BC.

Gene Signatures and Cancer-Immune Phenotypes Based on m6A Regulators in Breast Cancer

The N⁶-methyladenosine (m⁶A) has been considered as a new layer of epitranscriptomic regulation on mRNA processing, stability, and translation. However, potential roles of m⁶A RNA methylation modification in tumor immune microenvironment (TIME) of breast cancer are yet fully understood. In this study, we comprehensively evaluated the genetic variations and transcript expressions of 15 m⁶A regulators in 1,079 breast cancer samples from the Cancer Genome Atlas (TCGA) database. We validated major regulators had significantly differential mRNA and protein expression in tumor tissue compared to normal tissues from 39 pairs of clinical breast cancer samples with different molecular subtypes, and especially high expression of m⁶A readers YTHDF1 and YTHDF3 predicted poor survival. Two clusters of breast cancer patients identified by the 15 m⁶A regulators' pattern showed distinct overall survival, immune activation status, and immune cell infiltration, and clinical samples confirmed the diversity of lymphocytic infiltration. The profiles of these two clusters accorded with that of two classical cancer-immune phenotypes, immune-excluded and immune-inflamed phenotypes, it suggested that m⁶A regulators-based patterns might serve as crucial mediators of TIME in breast cancer. Moreover, the m⁶A phenotype-related gene signatures could also be survival predictor in breast cancer. Therefore, comprehensive evaluation of tumor m⁶A modification pattern will contribute to enhance our understanding of the characterization of immune cell infiltration in the tumor microenvironment and promote the responsiveness of breast cancer to immunotherapy.

Development of prognostic nomograms using institutional data for patients with triple-negative breast cancer

Background: Triple-negative breast cancer (TNBC) is an aggressive disease. Nomograms can predict prognosis of patients with TNBC. Methods: A total of 745 eligible TNBC patients were recruited and randomly divided into training and validation groups. Endpoints were disease-free survival and overall survival. Concordance index, area under the curve and calibration curves were used to analyze the predictive accuracy and discriminative ability of nomograms. Results: Based on the training cohort, neutrophil-to-lymphocyte ratio, positive lymph nodes, tumor size and tumor-infiltrating lymphocytes were used to construct a nomogram for disease-free survival. In addition, age was added to the overall survival nomogram. Conclusion: The current study developed and validated well-calibrated nomograms for predicting disease-free survival and overall survival in patients with TNBC.

Relationship between Th17 immune response and cancer

Cancer is the second leading cause of death worldwide and epidemiological projections predict growing cancer mortality rates in the next decades. Cancer has a close relationship with the immune system and, although Th17 cells are known to play roles in the immune response against microorganisms and in autoimmunity, studies have emphasized their roles in cancer pathogenesis. The Th17 immune response profile is involved in several types of cancer including urogenital, respiratory, gastrointestinal, and skin cancers. This type of immune response exerts pro and antitumor functions through several mechanisms, depending on the context of each tumor, including the protumor angiogenesis and exhaustion of T cells and the antitumor recruitment of T cells and neutrophils to the tumor microenvironment. Among other factors, the paradoxical behavior of Th17 cells in this setting has been attributed to its plasticity potential, which makes possible their conversion into other types of T cells such as Th17/Treg and Th17/Th1 cells. Interleukin (IL)-17 stands out among Th17-related cytokines since it modulates pathways and interacts with other cell profiles in the tumor microenvironment, which allow Th17 cells to prevail in tumors. Moreover, the IL-17 is able to mediate pro and antitumor processes that influence the development and progression of various cancers, being associated with variable clinical outcomes. The understanding of the relationship between the Th17 immune response and cancer as well as the singularities of carcinogenic processes in each type of tumor is crucial for the identification of new therapeutic targets.

Tumor-Infiltrating Lymphocyctes in Triple-Negative Breast Cancer: Update for 2020

ABSTRACT

Triple-negative breast cancer (TNBC) continues to represent an unmet need because of its significantly poorer outcomes, including higher relapse rates following early-stage disease and dismal survival times in the advanced setting, when compared with other breast cancer subtypes (Cancer 2012;118:5463-5472). Furthermore, there remains a lack of established systemic treatment options beyond conventional cytotoxic chemotherapy, with the exception of PARP inhibitors in the small subset of patients who harbor a BRCA mutation (N Engl J Med 2018;379:753; Lancet Oncol 2020;21:1269-1282; Ann Oncol 2019;30:558-566) and recently the use of immunotherapy in the first-line metastatic setting in those who are programmed death ligand 1-positive (Lancet Oncol 2020;21(1):44-59; N Engl J Med 2018;379(22):2108-2121). Suitable biomarkers for improving prognostication and directing therapy in both the early and advanced TNBC settings are required in order for improvements in survival outcomes to be continued to be attained. Tumor-infiltrating lymphocytes are gaining increasing relevance as an immunological biomarker in this arena.

Mathematical Model for Delayed Responses in Immune Checkpoint Blockades

We introduce a set of ordinary differential equations (ODEs) that qualitatively reproduce delayed responses observed in immune checkpoint blockade therapy (e.g. anti-CTLA-4 ipilimumab). This type of immunotherapy has been at the forefront of novel and promising cancer treatments over the past decade and was recognised by the 2018 Nobel Prize in Medicine. Our model describes the competition between effector T cells and non-effector T cells in a tumour. By calibrating a small subset of parameters that control immune checkpoint expression along with the patient's immune-system cancer readiness, our model is able to simulate either a complete absence of patient response to treatment, a quick anti-tumour T cell response (within days) or a delayed response (within months). Notably, the parameter space that generates a delayed response is thin and must be carefully calibrated, reflecting the observation that a small subset of patients experience such reactions to checkpoint blockade therapies. Finally, simulations predict that the anti-tumour T cell storm that breaks the delay is very short-lived compared to the length of time the cancer is able to stay suppressed. This suggests the tumour may subsist off an environment hostile to effector T cells; however, these cells are-at rare times-able to break through the tumour immunosuppressive defences to neutralise the tumour for a prolonged period. Our simulations aim to qualitatively describe the delayed response phenomenon without making precise fits to particular datasets, which are limited. It is our hope that our foundational model will stimulate further interest within the immunology modelling field.

Phase I/II trial of palbociclib, pembrolizumab and letrozole in patients with hormone receptor-positive metastatic breast cancer

BACKGROUND

CDK4/6 inhibitors modulate immune response in breast cancer. This phase I/II trial was designed to test the safety and efficacy of palbociclib, pembrolizumab and letrozole in women with hormone receptor positive (HR⁺) human epidermal growth factor receptor 2 negative (HER2^-) metastatic breast cancer (MBC).

PATIENTS AND METHODS

Women with stage IV HR⁺ HER2^- MBC were enrolled and treated with palbociclib, pembrolizumab and letrozole. Primary end-points were safety, tolerability and efficacy.

RESULTS

Between November 2016 and July 2020, 23 patients were enrolled with 20 evaluable for response, including 4 patients in cohort 1 and 16 patients in cohort 2. Cohort 1 median age was 48 years (33-70) and cohort 2 median age was 55 (37-75). Cohort 1 closed early due to limited accrual. Grade III-IV adverse events were neutropenia (83%), leucopaenia (65%), thrombocytopenia (17%) and elevated liver enzymes (17%). In cohort 1, 50% achieved a partial response (PR) and 50% had stable disease (SD). In cohort 2, 31% achieved complete response (CR), 25% had PR and 31% had SD by Response Evaluation Criteria in Solid Tumours version 1.1. Median progression-free survival was 25.2 months (95% confidence interval [CI] 5.3, not reached) and median overall survival was 36.9 months (95% CI 36.9, not reached) in cohort 2 with a median follow-up of 24.8 months (95% CI 17.1, not reached). A correlative immune biomarker analysis was published separately.

CONCLUSION

The combination of palbociclib, pembrolizumab and letrozole is well tolerated, and a complete response rate of 31% was identified in HR⁺ MBC patients who received this combination as front-line therapy. Confirmatory trials are required to better understand the immune-priming effects of CDK4/6 inhibitors.

A single-cell and spatially resolved atlas of human breast cancers

Breast cancers are complex cellular ecosystems where heterotypic interactions play central roles in disease progression and response to therapy. However, our knowledge of their cellular composition and organization is limited. Here we present a single-cell and spatially resolved transcriptomics analysis of human breast cancers. We developed a single-cell method of intrinsic subtype classification (SCSubtype) to reveal recurrent neoplastic cell heterogeneity. Immunophenotyping using cellular indexing of transcriptomes and epitopes by sequencing (CITE-seq) provides high-resolution immune profiles, including new PD-L1/PD-L2⁺ macrophage populations associated with clinical outcome. Mesenchymal cells displayed diverse functions and cell-surface protein expression through differentiation within three major lineages. Stromal-immune niches were spatially organized in tumors, offering insights into antitumor immune regulation. Using single-cell signatures, we deconvoluted large breast cancer cohorts to stratify them into nine clusters, termed 'ecotypes', with unique cellular compositions and clinical outcomes. This study provides a comprehensive transcriptional atlas of the cellular architecture of breast cancer.