Long-term Clinical Outcomes and Biomarker Analyses of Atezolizumab Therapy for Patients With Metastatic Triple-Negative Breast Cancer: A Phase 1 Study

Role of Surgical Pathologist for Detection of Predictive Immuno-oncological Factors in Breast Cancer

Immune checkpoint inhibitors (ICIs) have changed therapy strategies in breast cancer (BC) patients suffering from triple-negative breast cancer (TNBC). For example, in Europe the anti-programmed cell death 1 ligand 1 (PD-L1) ICI Azetolizumab is approved for adult patients with locally advanced or metastasized TNBC (mTNBC), depending on the immunohistochemical (IHC) PD-L1 expression of immune cells in the tumor area [immune cell (IC) score ≥1%); the anti-programmed cell death 1 (PD-1) ICI pembrolizumab is approved for mTNBC if PD-L1 Combined Positive Score (CPS), that is PD-L1 expression on tumor and/or immune cells, is ≥10. For early TNBC, in contrast, neoadjuvant use of pembrolizumab is approved in the United States and Europe independent from PD-L1 IHC expression. The determination of PD-L1 expression in tumor tissue to predict response to ICI therapy requires sensitive immunostaining with appropriate primary antibodies and staining protocols and a standardized and meticulous assessment of PD-L1 IHC stained breast cancer tissue slides. For the selection of the test material and continuous quality control of the dyeing, high standards must be applied. The evaluation is carried out according to various evaluation algorithms (scores). Here, the role of PD-L1 in BC and the currently most relevant PD-L1 assays and scores for TNBC will be explained. Furthermore, other tissue-based biomarkers potentially predictive for ICI therapy response in BC, for example, tumor mutational burden (TMB), will be presented in this review.

Immunotherapy for Metastatic Triple Negative Breast Cancer: Current Paradigm and Future Approaches

OPINION STATEMENT

In approximately 15-20% of the patients diagnosed with breast cancer, it comprises the triple negative (TN) subtype, which until recently lacked targets for specific treatments and is known for its aggressive clinical behavior in patients with metastatic disease. TNBC is considered the most immunogenic breast cancer subtype due to higher levels of tumor infiltrating lymphocytes (TILs), tumor mutational burden and PD-L1 expression, providing a rationale for immunotherapy. The addition of pembrolizumab to chemotherapy as first-line treatment resulted in significantly improved PFS and OS for PD-L1 positive mTNBC, leading to FDA approval. However, response rate of ICB in unselected patients is low. Ongoing (pre)clinical trials aim to further optimize ICB efficacy and widen its application beyond PD-L1 positive breast tumors. Novel immunomodulatory approaches to induce a more inflamed tumor microenvironment include dual checkpoint blockade, bispecific antibodies, immunocytokines, adoptive cell therapies, oncolytic viruses, and cancer vaccines. Preclinical data for these novel strategies seems promising, but solid clinical data to further support its application for mTNBC is awaited. Biomarkers capturing the degree of immunogenicity such as but not limited to TILs, CD8 T cell levels, and IFNg signatures could support deciding which therapeutic strategy is most appropriate for which patient. Given 1) the accumulating therapy options for patients with metastatic disease and 2) the heterogeneity of mTNBC from inflamed to immune-desert tumors, the challenge is to work towards immunomodulatory strategies for specific subgroups of patients with TNBC to enable personalized (immuno)therapy for patients with metastatic disease.

A phase II study of neoadjuvant atezolizumab and nab-paclitaxel in patients with anthracycline-resistant early-stage triple-negative breast cancer

PURPOSE

Neoadjuvant anti-PD-(L)1 therapy improves the pathological complete response (pCR) rate in unselected triple-negative breast cancer (TNBC). Given the potential for long-term morbidity from immune-related adverse events (irAEs), optimizing the risk-benefit ratio for these agents in the curative neoadjuvant setting is important. Suboptimal clinical response to initial neoadjuvant therapy (NAT) is associated with low rates of pCR (2-5%) and may define a patient selection strategy for neoadjuvant immune checkpoint blockade. We conducted a single-arm phase II study of atezolizumab and nab-paclitaxel as the second phase of NAT in patients with doxorubicin and cyclophosphamide (AC)-resistant TNBC (NCT02530489).

METHODS

Patients with stage I-III, AC-resistant TNBC, defined as disease progression or a < 80% reduction in tumor volume after 4 cycles of AC, were eligible. Patients received atezolizumab (1200 mg IV, Q3weeks × 4) and nab-paclitaxel (100 mg/m² IV,Q1 week × 12) as the second phase of NAT before undergoing surgery followed by adjuvant atezolizumab (1200 mg IV, Q3 weeks, × 4). A two-stage Gehan-type design was employed to detect an improvement in pCR/residual cancer burden class I (RCB-I) rate from 5 to 20%.

RESULTS

From 2/15/2016 through 1/29/2021, 37 patients with AC-resistant TNBC were enrolled. The pCR/RCB-I rate was 46%. No new safety signals were observed. Seven patients (19%) discontinued atezolizumab due to irAEs.

CONCLUSION

This study met its primary endpoint, demonstrating a promising signal of activity in this high-risk population (pCR/RCB-I = 46% vs 5% in historical controls), suggesting that a response-adapted approach to the utilization of neoadjuvant immunotherapy should be considered for further evaluation in a randomized clinical trial.

Status and prognostic value of immunological biomarkers of breast cancer

The immune response to cancer serves an important role in disease progression and patient prognosis. For triple-negative breast cancer showing aggressive behavior, immunotherapy has a good efficacy because of the potent immunogenicity of this type of cancer. However, the dominant subtype, luminal human epidermal growth factor receptor-2 (HER2)-negative breast cancer, is less immunogenic. To determine whether luminal HER2-negative cancer reacts to the anticancer immune response, the present study analyzed the status and prognostic value of the principal immunological biomarkers of breast cancer, including tumor-infiltrating lymphocytes (TILs), CD8⁺ T lymphocytes, the major histocompatibility complex and programmed cell death ligand-1 (PD-L1). The biomarkers were compared between patients with luminal HER2-negative breast cancer and those with immunogenic subtypes including triple-negative and HER2-overexpressed breast cancer. A total of 71 patients with primary breast cancer were classified into the immunogenic non-luminal (n=23) and less immunogenic luminal HER2-negative groups (n=48) based on immunogenicity. In the luminal HER2-negative group, compared with patients with low TIL levels, those with high TIL levels were at an advanced stage of cancer (P=0.024) and showed worse relapse-free survival (P=0.057); however, the remaining biomarkers exhibited no association with cancer progression or prognosis. In the non-luminal group, patients with high TIL levels showed significantly better RFS than those with low TIL levels (P=0.014). Compared with non-luminal patients negative for PD-L1, those positive for PD-L1 exhibited better overall survival (P=0.064). Notably, TIL status was found to exhibit contrasting prognostic predictions based on immunogenicity. In conclusion, TILs are a strong candidate for prognostic prediction in breast cancer, regardless of the subtype. PD-L1 is a potential candidate for prognostic prediction in immunogenic breast cancers, but not in the luminal HER2-negative subtype.

Association Between Biomarkers and Clinical Outcomes of Pembrolizumab Monotherapy in Patients With Metastatic Triple-Negative Breast Cancer: KEYNOTE-086 Exploratory Analysis

PURPOSE

In the two-cohort phase II KEYNOTE-086 study (ClinicalTrials.gov identifier: NCT02447003), first-line and second-line or later pembrolizumab monotherapy demonstrated antitumor activity in metastatic triple-negative breast cancer (mTNBC; N = 254). This exploratory analysis evaluates the association between prespecified molecular biomarkers and clinical outcomes.

METHODS

Cohort A enrolled patients with disease progression after one or more systemic therapies for metastatic disease irrespective of PD-L1 status; Cohort B enrolled patients with previously untreated PD-L1-positive (combined positive score [CPS] ≥ 1) metastatic disease. The association between the following biomarkers as continuous variables and clinical outcomes (objective response rate [ORR], progression-free survival [PFS], and overall survival [OS]) was evaluated: PD-L1 CPS (immunohistochemistry), cluster of differentiation 8 (CD8; immunohistochemistry), stromal tumor-infiltrating lymphocyte (sTIL; hematoxylin and eosin staining), tumor mutational burden (TMB; whole-exome sequencing [WES]), homologous recombination deficiency-loss of heterozygosity, mutational signature 3 (WES), mutational signature 2 (apolipoprotein B mRNA editing catalytic polypeptide-like; WES), T-cell-inflamed gene expression profile (Tcell_infGEP; RNA sequencing), and 10 non-Tcell_infGEP signatures (RNA sequencing); Wald test P values were calculated, and significance was prespecified at α = 0.05.

RESULTS

In the combined cohorts (A and B), PD-L1 (P = .040), CD8 (P < .001), sTILs (P = .012), TMB (P = .007), and Tcell_infGEP (P = .011) were significantly associated with ORR; CD8 (P < .001), TMB (P = .034), Signature 3 (P = .009), and Tcell_infGEP (P = .002) with PFS; and CD8 (P < .001), sTILs (P = .004), TMB (P = .025), and Tcell_infGEP (P = .001) with OS. None of the non-Tcell_infGEP signatures were associated with outcomes of pembrolizumab after adjusting for the Tcell_infGEP.

CONCLUSION

In this exploratory biomarker analysis from KEYNOTE-086, baseline tumor PD-L1, CD8, sTILs, TMB, and Tcell_infGEP were associated with improved clinical outcomes of pembrolizumab and may help identify patients with mTNBC who are most likely to respond to pembrolizumab monotherapy.

Clinical and biological heterogeneities in triple-negative breast cancer reveals a non-negligible role of HER2-low

Background

HER2-low could be found in some patients with triple-negative breast cancer (TNBC). However, its potential impacts on clinical features and tumor biological characteristics in TNBC remain unclear.

Methods

We enrolled 251 consecutive TNBC patients retrospectively, including 157 HER2-low (HER2low) and 94 HER2-negtive (HER2neg) patients to investigate the clinical and prognostic features. Then, we performed single-cell RNA sequencing (scRNA-seq) with another seven TNBC samples (HER2negvs. HER2low, 4 vs. 3) prospectively to further explore the differences of tumor biological properties between the two TNBC phenotypes. The underlying molecular distinctions were also explored and then verified in the additional TNBC samples.

Results

Compared with HER2neg TNBC, HER2low TNBC patients exhibited malignant clinical features with larger tumor size (P = 0.04), more lymph nodes involvement (P = 0.02), higher histological grade of lesions (P < 0.001), higher Ki67 status (P < 0.01), and a worse prognosis (P < 0.001; HR [CI 95%] = 3.44 [2.10–5.62]). Cox proportional hazards analysis showed that neoadjuvant systemic therapy, lymph nodes involvement and Ki67 levels were prognostic factors in HER2low TNBC but not in HER2neg TNBC patients. ScRNA-seq revealed that HER2low TNBC which showed more metabolically active and aggressive hallmarks, while HER2neg TNBC exhibited signatures more involved in immune activities with higher expressions of immunoglobulin-related genes (IGHG1, IGHG4, IGKC, IGLC2); this was further confirmed by immunofluorescence in clinical TNBC samples. Furthermore, HER2low and HER2neg TNBC exhibited distinct tumor evolutionary characteristics. Moreover, HER2neg TNBC revealed a potentially more active immune microenvironment than HER2low TNBC, as evidenced by positively active regulation of macrophage polarization, abundant CD8+ effector T cells, enriched diversity of T-cell receptors and higher levels of immunotherapy-targeted markers, which contributed to achieve immunotherapeutic response.

Conclusions

This study suggests that HER2low TNBC patients harbor more malignant clinical behavior and aggressive tumor biological properties than the HER2neg phenotype. The heterogeneity of HER2 may be a non-negligible factor in the clinical management of TNBC patients. Our data provide new insights into the development of a more refined classification and tailored therapeutic strategies for TNBC patients.

Surgical Management of Pancreatic Neuroendocrine Tumors

Pancreatic neuroendocrine tumors (PNETs) are relatively uncommon malignancies, characterized as either functional or nonfunctional secondary to their secretion of biologically active hormones. A wide range of clinical behavior can be seen, with the primary prognostic indicator being tumor grade as defined by the Ki67 proliferation index and mitotic index. Surgery is the primary treatment modality for PNETs. While functional PNETs should undergo resection for symptom control as well as potential curative intent, nonfunctional PNETs are increasingly managed nonoperatively. There is increasing data to suggest small, nonfunctional PNETs (less than 2 cm) are appropriate follow with nonoperative active surveillance. Evidence supports surgical management of metastatic disease if possible, and occasionally even surgical management of the primary tumor in the setting of widespread metastases. In this review, we highlight the evolving surgical management of local and metastatic PNETs.

Inflammation, Infiltration, and Evasion-Tumor Promotion in the Aging Breast

Breast cancer is a significant cause of morbidity and mortality in women, with over two million new cases reported worldwide each year, the majority of which occur in post-menopausal women. Despite advances in early detection and treatment, approximately one-third of patients diagnosed with breast cancer will develop metastatic disease. The pathogenesis and progression of breast cancer are influenced by a variety of biological and social risk factors, including age, ethnicity, pregnancy status, diet, and genomic alterations. Recent advancements in breast cancer research have focused on harnessing the power of the patient's adaptive and innate immune systems for diagnostic and therapeutic purposes. The breast immune microenvironment plays a critical role in regulating tissue homeostasis and resistance to tumorigenesis. In this review, we explore the dynamic changes in the breast immune microenvironment that occur with age, how these changes impact breast cancer development and progression, and how targeted therapeutic interventions that leverage the immune system can be used to improve patient outcomes. Our review emphasizes the importance of understanding the complex interplay between aging, the immune system, and breast cancer, and highlights the potential of immune-based therapies in the fight against this devastating disease.

Immunotherapy Targeting PD-1/PD-L1 in Early-Stage Triple-Negative Breast Cancer

The advent of immunotherapy, especially immune checkpoint inhibitors (ICIs), has revolutionized antitumor therapy. Programmed cell death receptor 1 (PD-1) and programmed cell death ligand 1 (PD-L1) are among the most promising targets for encouraging the immune system to eliminate cancer cells. PD-1/PD-L1 have made clinical remission for numerous solid tumors, including metastatic triple-negative breast cancer (TNBC). In recent years, integrating PD-1/PD-L1 inhibitors into existing treatments in early-stage TNBC has attracted wide attention. Herein, we summarize the clinical benefit of PD-1/PD-L1 inhibitors plus neoadjuvant chemotherapy, adjuvant chemotherapy, and targeted therapy in early-stage TNBC. Possible immunotherapy biomarkers, immune-related adverse events (irAEs), and the key challenges faced in TNBC anti-PD-1/PD-L1 therapy are also concluded. Numerous studies on immunotherapy are ongoing, and PD-1/PD-L1 inhibitors have demonstrated great clinical prospects in early-stage TNBC. To maximize the efficacy of anti-PD-1/PD-L1 therapy, further research into the challenges which still exist is necessary.

PD-L1 expression as biomarker of efficacy of PD-1/PD-L1 checkpoint inhibitors in metastatic triple negative breast cancer: A systematic review and meta-analysis

Background

Inhibitors of programmed cell death 1 (PD-1)/programmed cell death ligand 1(PD-L1) checkpoint have been approved for metastatic triple negative breast cancer (mTNBC) in patients positive for PD-L1 expression. Negative results from the recent phase III trials (IMPassion131 and IMPassion132) have raises questions on the efficacy of PD-1/PD-L1 checkpoint inhibitors and the predictive value of PD-L1 expression. Here we attempt to systematically analyze the biomarker value of PD-L1 expression for predicting the response of PD-1/PD-L1 checkpoint inhibitors in mTNBC.

Materials and methods

PubMed database was searched until Dec 2021 for studies evaluating PD-1/PD-L1 checkpoint inhibitors plus/minus chemotherapy in mTNBC. Outcome of interest included objective response rate (ORR), progression-free survival (PFS), and overall survival (OS). Review Manager (RevMan) version 5.4. was used for data-analysis.

Results

In total, 20 clinical trials comprising 3962 mTNBC patients (ICT: 2665 (67%); CT: 1297 (33%) were included in this study. Overall ORR was 22% (95%CI, 14-30%) and significant improvement was observed for PD-L1+ patients (ORR 1.78 [95%CI, 1.45-2.19], p<0.00001) as compared to PD-L1- cohort. Pooled outcome also indicated a significant 1-year PFS and 2-year OS advantage for patients with PD-L1 expression (1-year PFS: ORR 1.39 [95%CI, 1.04-1.85], p=0.02; I2 = 0%; 2-year OS: (ORR 2.47 [95%CI, 1.30-4.69], p=0.006; I2 = 63%). Subgroup analysis indicated that PD-L1 expression can successfully predict tumor response and 2-year OS benefit in mTNBC patients regardless of the type of investigating agent, line of treatment administration, and to some extent the type of treatment. Biomarker ability of PD-L1 expression to predict 1-year PFS was slightly better with pembrolizumab (p=0.09) than atezolizumab (p=0.18), and significantly better when treatment was administered in the first-line setting (OR 1.38 [95%CI, 1.02-1.87], p=0.04) and chemotherapy was added (OR 1.38 [95%CI, 1.02-1.86], p=0.03). Immune-related toxicity of any grade and grade≥3 was 39% (95%CI, 26%-52%) and 10% (95%CI, 8%-13%), respectively.

Conclusions

PD-L1 expression can predict objective response rate and 2-year OS in mTNBC patients receiving PD-1/PD-L1 checkpoint inhibitors. One-year PFS is also predicted in selected patients. PD-L1 expression can be a useful biomarker of efficacy of PD-1/PD-L1 checkpoint inhibitors in mTNBC.

Comparative Efficacy and safety of new targeted therapies and immunotherapies for metastatic triple negative breast cancer: a network meta-analysis

BACKGROUND

Several therapies directed at novel targets and also immunotherapies have recently shown promising results in advanced or metastatic TNBC. We aimed to compare the efficacy and safety of these new regimens for advanced or metastatic TNBC (mTNBC).

METHODS

The PubMed, Embase, and Cochrane Library electronic databases were searched for phase III randomized trials. We conducted a network meta-analysis to compare the efficacy and safety of new targeted and immunotherapy regimens. Trial quality was assessed using the GRADE method. The comparative outcomes were progression-free survival, overall survival, and G3-4 adverse drug events (ADEs).

RESULTS

Thirteen phase III randomized controlled trials were identified in the network meta-analysis. Olaparib significantly improved PFS in comparison with the pembrolizumab plus chemotherapy 1, atezolizumab plus nab-paclitaxel and pembrolizumab regimens. Sacituzumab yielded a significant improvement in OS over immunotherapies, veliparib, and chemotherapy alone, but no significantly superiority over pembrolizumab, olaparib, and talazoparib. The risk of ≥grade 3 ADEs associated with olaparib was significantly lower than the risks associated with the other regimens.

CONCLUSION

For mTNBC, sacituzumab had a better effect on overall survival, with comparatively high risk of SAE, whereas olaparib improved progression-free survival with a lower risk of SAE, particularly in those patients with BRCA mutations.

Tissue- and liquid biopsy-based biomarkers for immunotherapy in breast cancer

Immune checkpoint inhibitors (ICIs) have revolutionized cancer therapy and now represent the mainstay of treatment for many tumor types, including triple-negative breast cancer and two agnostic registrations. However, despite impressive durable responses suggestive of an even curative potential in some cases, most patients receiving ICIs do not derive a substantial benefit, highlighting the need for more precise patient selection and stratification. The identification of predictive biomarkers of response to ICIs may play a pivotal role in optimizing the therapeutic use of such compounds. In this Review, we describe the current landscape of tissue and blood biomarkers that could serve as predictive factors for ICI treatment in breast cancer. The integration of these biomarkers in a "holistic" perspective aimed at developing comprehensive panels of multiple predictive factors will be a major step forward towards precision immune-oncology.

Optimizing choices and sequences in the diagnostic-therapeutic landscape of advanced triple-negative breast cancer: An Italian consensus paper and critical review

Triple-negative (TN) metastatic breast cancer (mBC) represents the most challenging scenario withing mBC framework, and it has been only slightly affected by the tremendous advancements in terms of drug availability and survival prolongation we have witnessed in the last years for advanced disease. However, although chemotherapy still represents the mainstay of TN mBC management, in the past years, several novel effective agents have been developed and made available in the clinical practice setting. Within this framework, a panel composed of a scientific board of 17 internationally recognized breast oncologists and 42 oncologists working within local spoke centers, addressed 26 high-priority statements, including grey areas, regarding the management of TN mBC. A structured methodology based on a modified Delphi approach to administer the survey and the Nominal Group Technique to capture perceptions and preferences on the management of TN mBC within the Italian Oncology community were adopted. The Panel produced a set of prioritized considerations/consensus statements reflecting the Panel position on diagnostic and staging approach, first-line and second-line treatments of PD-L1-positive/germline BRCA (gBRCA) wild-type, PD-L1-positive/gBRCA mutated, PD-L1-negative/gBRCA wild-type and PD-L1-negative/gBRCA mutated TN mBC. The Panel critically and comprehensively discussed the most relevant and/or unexpected results and put forward possible interpretations for statements not reaching the consensus threshold.

Phase Ib study of talimogene laherparepvec in combination with atezolizumab in patients with triple negative breast cancer and colorectal cancer with liver metastases

BACKGROUND

Talimogene laherparepvec (T-VEC), a first-in-class oncolytic viral immunotherapy, enhances tumor-specific immune activation. T-VEC combined with atezolizumab, which blocks inhibitor T-cell checkpoints, could provide greater benefit than either agent alone. Safety/efficacy of the combination was explored in patients with triple negative breast cancer (TNBC) or colorectal cancer (CRC) with liver metastases.

METHODS

In this phase Ib, multicenter, open-label, parallel cohort study of adults with TNBC or CRC with liver metastases, T-VEC (10⁶ then 10⁸ PFU/ml; ≤4 ml) was administered into hepatic lesions via image-guided injection every 21 (±3) days. Atezolizumab 1200 mg was given on day 1 and every 21 (±3) days thereafter. Treatment continued until patients experienced dose-limiting toxicity (DLT), had complete response, progressive disease, needed alternative anticancer treatment, or withdrew due to an adverse event (AE). The primary endpoint was DLT incidence, and secondary endpoints included efficacy and AEs.

RESULTS

Between 19 March 2018 and 6 November 2020, 11 patients with TNBC were enrolled (safety analysis set: n = 10); between 19 March 2018 and 16 October 2019, 25 patients with CRC were enrolled (safety analysis set: n = 24). For the 5 patients in the TNBC DLT analysis set, no patient had DLT; for the 18 patients in the CRC DLT analysis set, 3 (17%) had DLT, all serious AEs. AEs were reported by 9 (90%) TNBC and 23 (96%) CRC patients, the majority with grade ≥3 [TNBC, 7 (70%); CRC, 13 (54%)], and 1 was fatal [CRC, 1 (4%)]. Evidence of efficacy was limited. Overall response rate was 10% (95% confidence interval 0.3-44.5) for TNBC; one (10%) patient had a partial response. For CRC, no patients had a response; 14 (58%) were unassessable.

CONCLUSIONS

The safety profile reflected known risks with T-VEC including risks of intrahepatic injection; no unexpected safety findings from addition of atezolizumab to T-VEC were observed. Limited evidence of antitumor activity was observed.

Variable Intrinsic Expression of Immunoregulatory Biomarkers in Breast Cancer Cell Lines, Mammospheres, and Co-Cultures

Advances in immunotherapy have increased interest in knowing the role of the immune system in breast cancer (BC) pathogenesis. Therefore, immune checkpoints (IC) and other pathways related to immune regulation, such as JAK2 and FoXO1, have emerged as potential targets for BC treatment. However, their intrinsic gene expression in vitro has not been extensively studied in this neoplasia. Thus, we evaluated the mRNA expression of tumor-cell-intrinsic CTLA-4, PDCD1 (PD1), CD274 (PD-L1), PDCD1LG2 (PD-L2), CD276 (B7-H3), JAK2, and FoXO1 in different BC cell lines, derived mammospheres, and co-cultures with peripheral blood mononuclear cells (PBMCs) by real-time quantitative polymerase chain reaction (qRT-PCR). Our results showed that intrinsic CTLA-4, CD274 (PD-L1), and PDCD1LG2 (PD-L2) were highly expressed in triple-negative cell lines, while CD276 was predominantly overexpressed in luminal cell lines. In contrast, JAK2 and FoXO1 were under-expressed. Moreover, high levels of CTLA-4, PDCD1 (PD1), CD274 (PD-L1), PDCD1LG2 (PD-L2), and JAK2 were found after mammosphere formation. Finally, the interaction between BC cell lines and peripheral blood mononuclear cells (PBMCs) stimulates the intrinsic expression of CTLA-4, PCDC1 (PD1), CD274 (PD-L1), and PDCD1LG2 (PD-L2). In conclusion, the intrinsic expression of immunoregulatory genes seems very dynamic, depending on BC phenotype, culture conditions, and tumor-immune cell interactions.

Novel diagnostic biomarkers of T cell-mediated tumor killing characteristics for early-stage triple negative breast cancer: A SEER analysis and molecular portraits

The primary objective was to investigate the epidemiology, molecular characteristics, and clinical survival to identify potential transcriptome biomarkers to promote early diagnosis and screening of triple-negative breast cancer patients. Early-stage triple-negative breast cancer patients (E-TNBC) and late-stage triple-negative breast cancer patients (L-TNBC) were identified from the Surveillance, Epidemiology, and End Results database from 2010 to 2019. The difference in cancer specific survival (CSS) and overall survival (OS) between E-TNBC and L-TNBC was analyzed via a Kaplan-Meier plotter. 118 triple-negative breast cancer samples and 114 normal samples with the RNA sequencing expression data were selected from the cohort of TCGA breast cancer from UCSC Xena Database. The study involved 13,690 patients with L-TNBC and 44,994 patients with E-TNBC. L-TNBC patients were more frequently to be ≤ 60 years old (54.9% vs 52.2%), multiple primary site (44.0% vs 30.1%), and were more likely to receive radiotherapy (49.6% vs 47.4%) and chemotherapy (81.1% vs 72.1%), while L-TNBC patients were less likely to be white (68.7% vs 73.0%), married or with domestic partner (46.7% vs 54.7%), poorly differentiated grade (54.0% vs 61.9%), < 3 months from diagnosis to treatment (91.6% vs 96.4%), and were less likely to receive surgery (72.3% vs 95.4%). Stage-stratified survival analysis revealed that the prognosis of L-TNBC was worse when compared to E-TNBC, Kaplan-Meier analysis demonstrated that there were striking differences in OS and CSS between E-TNBC and L-TNBC. In the multivariable regression models, L-TNBC was the single highest risk factor, with a death risk that was 4.741 and 6.074 times higher than E-TNBC in terms of OS and CSS, respectively. The results also showed that treatment with surgery, radiation, or chemotherapy was effective for a better prognosis. Transcriptome analyses revealed that the top 5 upregulated genes in L-TNBC were, respectively, ISX, ALOX15B, MADCAM1, TP63, and ARG1 compared with E-TNBC. And the top 5 downregulated genes were, respectively, CTAG1B, CT45A1, MAGEC2, TFF2, and TNFRSF11B. The L-TNBC exhibited a lower rate of survival than E-TNBC, and the 2 groups differed in terms of transcriptome characteristics. To date, the diagnostic value of T cell-mediated tumor killing portraits on E-TNBC may not be completely recognized.

Efficacy of PARP Inhibitor, Platinum, and Immunotherapy in BRCA-Mutated HER2-Negative Breast Cancer Patients: A Systematic Review and Network Meta-Analysis

The optimal treatment regimen for breast cancer patients with gBRCA mutations remains controversial given the availability of numerous options, such as platinum-based agents, polymerase inhibitors (PARPis), and other agents. We included phase II or III RCTs and estimated the HR with 95% CI for OS, PFS, and DFS, in addition to the OR with 95% CI for ORR and pCR. We determined the treatment arm rankings by P-scores. Furthermore, we carried out a subgroup analysis in TNBC and HR-positive patients. We conducted this network meta-analysis using R 4.2.0 and a random-effects model. A total of 22 RCTs were eligible, involving 4253 patients. In the pairwise comparisons, PARPi + Platinum + Chemo was better than PARPi + Chemo for OS (in whole study group and in both subgroups) as well as PFS. The ranking tests demonstrated that PARPi + Platinum + Chemo ranked first in PFS, DFS, and ORR. Platinum + Chemo showed higher OS than PARPi + Chemo. The ranking tests for PFS, DFS, and pCR indicated that, except for the best treatment (PARPi + Platinum + Chemo) containing PARPi, the second and third treatments were platinum monotherapy or platinum-based chemotherapy. In conclusion, PARPi + Platinum + Chemo might be the best regime for gBRCA-mutated BC. Platinum drugs showed more favorable efficacy than PARPi in both combination and monotherapy.

Critical Review on the Different Roles of Exosomes in TNBC and Exosomal-Mediated Delivery of microRNA/siRNA/lncRNA and Drug Targeting Signalling Pathways in Triple-Negative Breast Cancer

Triple-negative breast cancer is the most potent metastatic type of breast cancer that can spread to other body parts. Chemotherapy and surgical intervention are the sole treatments for TNBC, owing to the scarcity of therapeutic targets. Manipulation of the membranes as per the desired targets of exosomes has recently gained much attention as a drug delivery method. Despite their known roles in different diseases, very few studies have focused on signalling that triggers the metastasis of triple-negative breast cancer to other body parts by exosomes. This article highlights the significant roles of exosomes associated with TNBC, the involvement of exosomes in breast cancer diagnosis, progression, and the treatment of triple-negative breast cancer by the exosomes as a drug delivery system. This review paper also illustrates the role of exosomes in initiating EMT in breast cancer, including novel signalling.

Immunotherapy in breast cancer: an overview of current strategies and perspectives

Recent progress in immunobiology has led the way to successful host immunity enhancement against breast cancer. In triple-negative breast cancer, the combination of cancer immunotherapy based on PD-1/PD-L1 immune checkpoint inhibitors with chemotherapy was effective both in advanced and early setting phase 3 clinical trials. These encouraging results lead to the first approvals of immune checkpoint inhibitors in triple-negative breast cancer and thus offer new therapeutic possibilities in aggressive tumors and hard-to-treat populations. Furthermore, several ongoing trials are investigating combining immunotherapies involving immune checkpoint inhibitors with conventional therapies and as well as with other immunotherapeutic strategies such as cancer vaccines, CAR-T cells, bispecific antibodies, and oncolytic viruses in all breast cancer subtypes. This review provides an overview of immunotherapies currently under clinical development and updated key results from clinical trials. Finally, we discuss the challenges to the successful implementation of immune treatment in managing breast cancer and their implications for the design of future clinical trials.

Novel roles of RNA-binding proteins in drug resistance of breast cancer: from molecular biology to targeting therapeutics

Therapy resistance remains a huge challenge for current breast cancer treatments. Exploring molecular mechanisms of therapy resistance might provide therapeutic targets for patients with advanced breast cancer and improve their prognosis. RNA-binding proteins (RBPs) play an important role in regulating therapy resistance. Here we summarize the functions of RBPs, highlight their tremendously important roles in regulating therapy sensitivity and resistance and we also reveal current therapeutic approaches reversing abnormal functions of RBPs in breast cancer.

LAG-3 expression in tumor microenvironment of triple-negative breast cancer

BACKGROUND

This study aimed to evaluate the expression of lymphocyte activation gene-3 (LAG-3) and its relationship with programmed cell death ligand-1 (PD-L1) in triple-negative breast cancer (TNBC).

METHODS

: LAG-3 and PD-L1 was evaluated in tumor-infiltrating lymphocytes (TILs) using immunohistochemistry (IHC). The chi-square test was used to estimate the associations between LAG-3, PD-L1 and clinicopathological characteristics. Correlation between LAG-3 stromal TIL (sTIL), LAG-3 intraepitelial TIL (iTIL) and PD-L1 was assessed with using the Spearman's correlation coefficient. Survival analysis was performed using the Kaplan-Meier method.

RESULTS

The percentages of LAG-3 sTIL+, LAG-3 iTIL+, PD-L1+ tumor cells and PD-L1+ inflammatory cells were 52%, 42%, 14% and 70%, respectively. A strong positive correlation between LAG-3 sTIL and LAG-3 iTIL (r = 0.874, p < 0.001) and a moderate positive correlation between LAG-3 sTIL and PD-L1 (r = 0.584, p < 0.001) were found. LAG-3 and PD-L1 status did not significantly affect overall survival (OS) (HR: 0.56 (95% CI: 0.15-2.11) (p = 0.397), HR: 2.70 (95% CI: 0.56-13.02) (p = 0.215), respectively).

DISCUSSION

High levels of LAG-3 and PD-L1 expression were detected in patients with TNBC. Although their contribution to survival could not be determined, the high expression rates of PD-L1 and LAG-3 may help identify the subgroup of TNBC that would benefit from immunotherapy.

The role of immune checkpoint inhibitors in patients with intracranial metastatic disease

Intracranial metastatic disease (IMD) complicates the course of nearly 2-4% of patients with systemic cancer. The prevalence of IMD has been increasing over the past few decades. Historically, definitive treatment for brain metastases (BM) has been limited to radiation therapy or surgical resection. Chemotherapies have not typically proven valuable in the treatment of IMD, with the exception of highly chemotherapy-sensitive lesions. Recent data have supported a role for systemic targeted therapies and immune checkpoint inhibitors (ICIs) in the treatment of select patients with IMD. There remains, however, a clear clinical need for further investigation to delineate the role of ICIs in patients with BM. In this review, we outline and describe recent and current efforts to identify the efficacy of ICI therapy in patients with IMD.

Manganese-enriched photonic/catalytic nanomedicine augments synergistic anti-TNBC photothermal/nanocatalytic/immuno-therapy via activating cGAS-STING pathway

As the clinical efficacy of immunotherapy for triple-negative breast cancer (TNBC) remains limited, exploring new immunotherapy approaches is still indispensable. Mn²⁺ has been proven as a cGAS-STING agonist to remarkably enhance antitumor immunity. Here, we report a combined tumor-therapeutic strategy based on Prussian blue (PB)-mediated photothermal therapy with Mn²⁺-augmented immunotherapy by synergistically activating the cGAS-STING pathway. Mn-enriched photonic nanomedicine (MnPB-MnO_x) were constructed by integrating MnO_x onto the surface of Mn-doped PB nanoparticles. All components of MnPB-MnO_x are biocompatible and biodegradable, wherein sufficient Mn are endowed through rational nanostructure design, conferring easier cGAS-STING activation. Additionally, tumor hyperthermia strengthened by MnPB under near-infrared light radiation, synergistic with the generation of reactive oxygen species catalyzed by MnO_x, double hits cancer cells to release abundant tumor-associated antigens for further promoting immune response stimulation. The local anti-TNBC efficacy of photothermal/immuno-therapy has been proven effective in subcutaneous 4T1-bearing mice. Especially, it has been systematically demonstrated in bilateral orthotopic 4T1-bearing mice that the as-proposed treatment could successfully activate innate and adaptive immunity, and local therapy could engender systemic responses to suppress the distant tumors. Collectively, this work represents a proof-of-concept for a non-invasive Mn-based tumor-immunotherapeutic modality, providing a paradigm for the immunotherapy of metastatic-prone tumors.

Targeting Notch-Driven Cytokine Secretion: Novel Therapies for Triple Negative Breast Cancer

Compared with other breast cancer subtypes, triple negative breast cancer (TNBC) is an aggressive malignancy with a high recurrence rate and reduced overall survival. Immune checkpoint inhibition (ICI) has shown modest results in this subgroup, highlighting the need for improved targeted therapeutic options. Notch is a defining feature of TNBC and drives the expression of interleukin-1 beta (IL1β) and C-C motif chemokine ligand 2 (CCL2). These cytokines are involved in the recruitment of tumor-associated macrophages (TAMs) to the tumor, resulting in immune evasion and tumor progression. Targeting Notch, IL1β or CCL2 may reduce TAM recruitment and resistance to ICI, illuminating the potential of combination immunotherapy in TNBC.

Role of Immunotherapy in Early- and Late-Stage Triple-Negative Breast Cancer

For women with triple-negative breast cancer, the addition of pembrolizumab to chemotherapy has become a standard of care in the early-stage and first-line metastatic setting. However, many questions persist. Different chemotherapy backbones and sequencing strategies have been evaluated, but evidence supporting the superiority of one over the other is weak. Although many have been investigated, programmed cell death ligand 1 (PDL1) is the only approved biomarker. Since immunotherapy has been associated with potentially severe and permanent toxicities, the identification of better predictive biomarkers is essential. New strategies are needed to increase the proportion of patients who might benefit from immunotherapy.

Efficacy and Safety of Immune Checkpoint Inhibitors in Triple-negative Breast Cancer: A Study Based on 41 Cohorts Incorporating 6558 Participants

The project was designed to investigate the efficacy and safety of immune checkpoint inhibitors (ICIs) in triple-negative breast cancer (TNBC). Electronic databases were screened to identify relevant trials. The primary endpoints were prognostic parameters and adverse events (AEs) through pooled rate, odds ratio, and hazard ratio (HR) with 95% CI. Totally, 6558 TNBC patients from 41 cohorts were included. The pooled pathologic complete response rate (odds ratio=2.03, 95% CI: 1.35-3.06, P =0.0007) and event-free survival (HR=0.84, 95% CI: 0.73-0.96, P =0.0100) of ICIs plus chemotherapy was higher than that of chemotherapy-alone in early-stage TNBC. For metastatic TNBC, compared with chemotherapy-alone, the addition of ICIs prolonged the progression-free survival (PFS) (HR=0.92, 95% CI: 0.88-0.96, P <0.0001); the improvement also existed in the following 3 subgroups: programmed cell death-ligand 1 positive, race of White and Asian, and patients without previous neoadjuvant or adjuvant chemotherapy; however, the benefit of the combined regimen was not observed in overall survival (OS) (HR=0.95; 95% CI: 0.89-1.03, P =0.2127). In addition, the pooled rates of OS, PFS, and objective response rate of ICIs plus chemotherapy were better than those of ICIs plus targeted therapy or ICIs-alone. In the safety analysis, compared with chemotherapy-alone, ICIs plus chemotherapy increased immune-related AEs and several serious AE. The regimen of ICIs plus chemotherapy is promising in both early-stage and metastatic TNBC, while the increased serious AE should not be neglected. Furthermore, the pooled rates of OS, PFS, and objective response rate of ICIs plus chemotherapy were better than those of ICIs plus targeted therapy or ICIs-alone.

Prospect of neoadjuvant/adjuvant immunotherapy in early-stage triple-negative breast cancer

China is bearing the growing burden of breast cancer globally, accounting for 18% of all new cases. Triple-negative breast cancer (TNBC) is aggressive, prone to early recurrence and metastasis, with a poor prognosis. Improving the prognosis at the early-stage of TNBC remains a challenge, due to the limited efficacy of traditional neoadjuvant/adjuvant chemotherapy. Early studies revealed that early-stage TNBC is more immunogenic. Several current clinical trials revealed that the combination with immunotherapy in the form of immune checkpoint inhibitors (ICIs) expands the treatment options for early-stage TNBC by improving the pathologic complete response (pCR), as well as long-term survival benefits. Correspondingly, Chinese Society of Clinical Oncology (CSCO) updated the breast cancer guidelines to include several recommendations regarding neoadjuvant/adjuvant immunotherapy. However, relevant immunotherapy data in Chinese patients with early-stage TNBC remain scarce. The cTRIO clinical trial (ChiCTR2100041675) is a multicenter phase II trial initiated by investigators to evaluate tislelizumab combined with nab-paclitaxel and carboplatin in neoadjuvant/ adjuvant therapy for Chinese patients with TNBC. In this review, we discuss the latest advances in clinical studies of neoadjuvant/adjuvant immunotherapy for early-stage TNBC, as well as potential challenges and strategies to improve the clinical outcomes. We introduce the study design of the cTRIO trial, which aims to make the clinical benefits more robust for early-stage TNBC patients in China.

Predictive Biomarkers for Response to Immunotherapy in Triple Negative Breast Cancer: Promises and Challenges

Triple negative breast cancer (TNBC) is a highly heterogeneous disease with a poor prognosis and a paucity of therapeutic options. In recent years, immunotherapy has emerged as a new treatment option for patients with TNBC. However, this therapeutic evolution is paralleled by a growing need for biomarkers which allow for a better selection of patients who are most likely to benefit from this immune checkpoint inhibitor (ICI)-based regimen. These biomarkers will not only facilitate a better optimization of treatment strategies, but they will also avoid unnecessary side effects in non-responders, and limit the increasing financial toxicity linked to the use of these agents. Huge efforts have been deployed to identify predictive biomarkers for the ICI, but until now, the fruits of this labor remained largely unsatisfactory. Among clinically validated biomarkers, only programmed death-ligand 1 protein (PD-L1) expression has been prospectively assessed in TNBC trials. In addition to this, microsatellite instability and a high tumor mutational burden are approved as tumor agnostic biomarkers, but only a small percentage of TNBC fits this category. Furthermore, TNBC should no longer be approached as a single biological entity, but rather as a complex disease with different molecular, clinicopathological, and tumor microenvironment subgroups. This review provides an overview of the validated and evolving predictive biomarkers for a response to ICI in TNBC.

Immunotherapy and tumor mutational burden in cancer patients with liver metastases: A meta and real word cohort analysis

Background

The predictive effects of liver metastases for immune-checkpoint inhibitors (ICIs) and the relationship between tumor mutational burden (TMB) and liver metastases (LM) remain unclear.

Methods

A systematic review and meta-analysis were conducted to explore the heterogeneity of ICIs efficacy between patients with or without LM. A pan-cancer cohort of 1,661 patients who received ICIs was downloaded and analyzed to assess the association between TMB and LM.

Results

Of 21053 studies identified in our search, eight single-arm studies and 24 randomized controlled trials were included. Overall, 17957 patients with advanced or metastatic cancers (4805 patients (26.8%) with LM and 13151 patients (73.2%) without LM) were enrolled. The pooled objective response rate (ORR) was 8.5% (95% CI 4%-13%) in the LM group versus 21% (95% CI 16%-21%) in the non-LM group. The pooled hazard ratio (HR) for death was 0.85 (95% CI 0.80-0.90) in the LM group treated with ICIs compared with the standard of care. In patients without LM who were treated with ICIs, the pooled HR for death was 0.78 (95% CI 0.73-0.82) compared with the standard of care. The difference in efficacy between patients with or without LM treated with ICIs was significant (p=0.04). Pan-cancer analysis revealed that the TMB-high rate was 10.8% in liver metastatic lesions versus 21.4% in other metastatic lesions (p=0.004). In addition, TMB was also significantly associated with OS as a binary cutoff (p=0.05) and was an independent prognostic variable (HR=0.98, P=0.047) as a continuous variable in patients with LM.

Conclusions

In patients with LM, the efficacy of immunotherapy was attenuated, but TMB-high could predict better survival outcomes.

CD8+ T cell-intrinsic IL-6 signaling promotes resistance to anti-PD-L1 immunotherapy

Although immune checkpoint inhibitors (ICIs) are established as effective cancer therapies, overcoming therapeutic resistance remains a critical challenge. Here we identify interleukin 6 (IL-6) as a correlate of poor response to atezolizumab (anti-PD-L1) in large clinical trials of advanced kidney, breast, and bladder cancers. In pre-clinical models, combined blockade of PD-L1 and the IL-6 receptor (IL6R) causes synergistic regression of large established tumors and substantially improves anti-tumor CD8⁺ cytotoxic T lymphocyte (CTL) responses compared with anti-PD-L1 alone. Circulating CTLs from cancer patients with high plasma IL-6 display a repressed functional profile based on single-cell RNA sequencing, and IL-6-STAT3 signaling inhibits classical cytotoxic differentiation of CTLs in vitro. In tumor-bearing mice, CTL-specific IL6R deficiency is sufficient to improve anti-PD-L1 activity. Thus, based on both clinical and experimental evidence, agents targeting IL-6 signaling are plausible partners for combination with ICIs in cancer patients.

Immunotherapy: Review of the Existing Evidence and Challenges in Breast Cancer

Breast cancer (BC) is a representative malignant tumor that affects women across the world, and it is the main cause of cancer-related deaths in women. Although a large number of treatment methods have been developed for BC in recent years, the results are sometimes unsatisfying. In recent years, treatments of BC have been expanded with immunotherapy. In our article, we list some tumor markers related to immunotherapy for BC. Moreover, we introduce the existing relatively mature immunotherapy and the markers' pathogenesis are involved. The combination of immunotherapy and other therapies for BC are introduced in detail, including the combination of immunotherapy and chemotherapy, the combined use of immunosuppressants and chemotherapy drugs, immunotherapy and molecular targeted therapy. We summarize the clinical effects of these methods. In addition, this paper also makes a preliminary exploration of the combination of immunotherapy, radiotherapy, and nanotechnology for BC.

Theranostics for Triple-Negative Breast Cancer

Triple-negative breast cancer (TNBC) is an aggressive subtype of breast cancer with poor prognosis. Current endocrine therapy or anti HER-2 therapy is not available for these patients. Chemotherapeutic treatment response varies among patients due to the disease heterogeneity. To overcome these challenges, theranostics for treating TNBC have been widely investigated. Anticancer material conjugated nanoparticles with target-binding ligand and tracer agents enable simultaneous drug delivery and visualization of the lesion with minimal off-target toxicity. In this review, we summarize recently FDA-approved targeted therapies for TNBC, such as poly-ADP-ribose polymerase (PARP) inhibitors, check point inhibitors, and antibody-drug conjugates. Particularly, novel theranostic approaches including lipid-based, polymer-based, and carbon-based nanocarriers are discussed, which can provide basic overview of nano-therapeutic modalities in TNBC diagnosis and treatment.

Role of Immunotherapy in Breast Cancer

The advent of immunotherapy, particularly immune checkpoint inhibitors (ICIs), has revolutionized the treatment of solid tumor malignancies. In breast cancer, the most robust data to date for ICI exist for triple-negative breast cancer (TNBC). Preclinical studies suggested increased antitumoral immune response in patients with TNBC undergoing ICI treatment. Early clinical trials investigated the use of ICI monotherapy in patients with metastatic TNBC with promising results, particularly in the first-line setting and for those patients whose tumors had high programmed cell death 1 (PD-1) or programmed cell death ligand 1 (PD-L1) expression. Subsequent trials evaluated the use of ICI in combination with conventional chemotherapy to enhance the host immune response. Pembrolizumab combined with chemotherapy in the KEYNOTE-355 study resulted in improved progression-free survival and overall survival benefits for patients with PD-L1 combined positive score > 10 metastatic TNBC. In early-stage disease, two phase III trials demonstrated increased rates of pathologic complete response at the time of surgery with the addition of neoadjuvant ICI to standard chemotherapy. The large KEYNOTE-522 trial showed improved event-free survival with neoadjuvant and adjuvant ICI. Several biomarkers have been identified, which may be predictive of response to ICI therapy including PD-1/PD-L1 expression, tumor mutational burden, tumor-infiltrating lymphocytes, and multigene assays capturing favorable immune cell signatures. For hormone receptor-positive and human epidermal growth factor receptor-positive breast cancer, there are ongoing studies evaluating ICI therapy in combination with chemotherapy and targeted agents. Finally, across all subtypes, several novel immunotherapeutic agents are under investigation including novel ICIs, cancer vaccines, adoptive cellular therapy, and oncolytic viruses.

Molecular Imaging of Oxygenation Changes during Immunotherapy in Combination with Paclitaxel in Triple Negative Breast Cancer

Hypoxia is a common feature of the tumor microenvironment, including that of triple-negative breast cancer (TNBC), an aggressive breast cancer subtype with a high five-year mortality rate. Using [18F]-fluoromisonidazole (FMISO) positron emission tomography (PET) imaging, we aimed to monitor changes in response to immunotherapy (IMT) with chemotherapy in TNBC. TNBC-tumor-bearing mice received paclitaxel (PTX) ± immune checkpoint inhibitors anti-programmed death 1 and anti-cytotoxic T-lymphocyte 4. FMISO-PET imaging was performed on treatment days 0, 6, and 12. Max and mean standard uptake values (SUVmax and SUVmean, respectively), histological analyses, and flow cytometry results were compared. FMISO-PET imaging revealed differences in tumor biology between treatment groups prior to tumor volume changes. 4T1 responders showed SUVmean 1.6-fold lower (p = 0.02) and 1.8-fold lower (p = 0.02) than non-responders on days 6 and 12, respectively. E0771 responders showed SUVmean 3.6-fold lower (p = 0.001) and 2.7-fold lower (p = 0.03) than non-responders on days 6 and 12, respectively. Immunohistochemical analyses revealed IMT plus PTX decreased hypoxia and proliferation and increased vascularity compared to control. Combination IMT/PTX recovered the loss of CD4+ T-cells observed with single-agent therapies. PET imaging can provide timely, longitudinal data on the TNBC tumor microenvironment, specifically intratumoral hypoxia, predicting therapeutic response to IMT plus chemotherapy.

Immunotherapy for Triple-Negative Breast Cancer: Combination Strategies to Improve Outcome

Due to the absence of hormone receptor (both estrogen receptors and progesterone receptors) along with human epidermal growth factor receptor 2 (HER-2) amplification, the treatment of triple-negative breast cancer (TNBC) cannot benefit from endocrine or anti-HER-2 therapy. For a long time, chemotherapy was the only systemic treatment for TNBC. Due to the lack of effective treatment options, the prognosis for TNBC is extremely poor. The successful application of immune checkpoint inhibitors (ICIs) launched the era of immunotherapy in TNBC. However, the current findings show modest efficacy of programmed cell death- (ligand) 1 (PD-(L)1) inhibitors monotherapy and only a small proportion of patients can benefit from this approach. Based on the basic principles of immunotherapy and the characteristics of the tumor immune microenvironment (TIME) in TNBC, immune combination therapy is expected to further enhance the efficacy and expand the beneficiary population of patients. Given the diversity of drugs that can be combined, it is important to select effective biomarkers to identify the target population. Moreover, the side effects associated with the combination of multiple drugs should also be considered.

Surface-engineered nanoparticles in cancer immune response and immunotherapy: Current status and future prospects

Cancer immunotherapy is a therapeutic strategy to inhibit tumor growth and metastasis by intervening in the immune response process. Strategies applied to cancer immunotherapy mainly include blocking immune checkpoints, adoptive transfer of engineered immune cells, cytokine therapy, cancer vaccines, and oncolytic virus infection. However, many factors, such as off-target side effects, immunosuppressive cell infiltration and/or upregulation of immune checkpoint expression, cancer cell heterogeneity, and lack of antigen presentation, affect the therapeutic effect of immunotherapy on cancer. To improve the efficacy of targeted immunotherapy and reduce off-target effects, over the past two decades, nanoparticle delivery platforms have been increasingly used in tumor immunotherapy. However, nanoparticles are still subject to biological barriers and biodistribution challenges, which limit their overall clinical potential. This has prompted a series of engineered nanoparticles to overcome specific obstacles and transfer the accumulation of payloads to tumor-infiltrating immune cells. In recent years, new techniques and chemical methods have been employed to modify or functionalize the surfaces of nanoparticles. This review discusses the recent progress of surface-engineered nanoparticles in inducing tumor immune responses and immunotherapy, as well as future directions for the development of next-generation nanomedicines.

Efficacy and Safety of Atezolizumab Monotherapy or Combined Therapy with Chemotherapy in Patients with Metastatic Triple-negative Breast Cancer: A Systematic Review and Meta-analysis of Randomized Controlled Trials

INTRODUCTION

Several successful attempts have been recorded with PD-L1 blockade via atezolizumab monotherapy or combination therapy with chemotherapy in patients with metastatic triple-negative breast cancer (mTNBC). Due to the lack of a large-scale study, we present a meta-analysis aimed at evaluating the safety and efficacy of this promising strategy in patients with mTNBC.

METHODS

A comprehensive literature search was conducted using electronic databases to identify eligible RCTs. Twelve studies, including 2479 mTBNC patients treated with atezolizumab monotherapy or in combination with chemotherapy, were included up to January 2022. The PRISMA checklist protocol and the I2 statistic were applied for quality assessment and heterogeneity tests of the selected trials, respectively. Fixed and random-effects models were estimated based on the heterogeneity tests, and statistical analysis was performed using CMA.

RESULTS

Our pooled findings demonstrated that the median overall survival (OS) and progression-free survival (PFS) were 16.526 and 5.814 months in mTNBC patients, respectively. Furthermore, when comparing efficacy indicators between PD-L1-positive and PD-L1-negative groups, mTNBC patients with PD-L1 had better OS, PFS, and ORR than PD-L1-negative patients. Also, the immune-related adverse event incident for alopecia was higher (51.9%) than other complications across atezolizumab therapy.

CONCLUSION

Moreover, the pooled analysis indicated that the overall rate of lung metastasis following atezolizumab therapy was 42.8%, which was higher than the rates of metastasis in bone (26.9%), brain (5.4%), and lymph node (6.5%). Atezolizumab showed a manageable safety profile and had promising and durable anti-tumor efficacy in TMBC patients. Higher PD-L1 expression may be closely correlated with better clinical efficacy.

Pembrolizumab in Lymphopenic Metastatic Breast Cancer Patients Treated with Metronomic Cyclophosphamide: A Clinical and Translational Prospective Study

Purpose

Metastatic endocrine-resistant breast cancer (MBC) is a disease with poor prognosis and few treatment options. Low lymphocyte count is associated with limited overall survival. In a prospective cohort of lymphopenic patients with HER-2 negative MBC, we assessed the clinical and biological impact of pembrolizumab combined with metronomic cyclophosphamide.

Experimental Design

This multicenter Phase II study evaluated the safety and clinical activity of pembrolizumab (intravenous (IV), 200mg, every 3 weeks) combined with metronomic cyclophosphamide (50mg/day, per os) in lymphopenic adult patients with HER2-negative MBC previously treated by at least one line of chemotherapy in this setting according to a Simon's minimax two-stage design. Blood and tumor samples were collected to assess the impact of the combined treatment on circulating immune cells and the tumor immune microenvironment through multiparametric flow cytometry and multiplex immunofluorescence analyses. Primary endpoint was the clinical benefit rate at 6 months of treatment (CBR-6M). Secondary endpoints were objective response rate (ORR), duration of response, progression free survival (PFS), and overall survival (OS).

Results

Two out of the twenty treated patients presented clinical benefit (one Tumor Mutational Burden (TMB)-high patient with complete response (CR) and one patient with objective response (OR) per Response Evaluation Criteria in Solid Tumors version 1.1 (RECIST V1.1) associated with a strong increase of cytokine-producing and proliferating CD4⁺ T cells and higher CD8⁺ T cells to macrophage ratios in the tumor. This impact on CD4⁺ and CD8⁺ T cell polyfunctionality was still observed more than one year for the patient with CR. A decreased in their absolute number of CD4⁺ and CD8⁺ memory T cells was observed in other patients.

Conclusion

Pembrolizumab combined with metronomic cyclophosphamide was well tolerated, and displayed limited anti-tumoral activity in lymphopenic MBC. Correlative translational data of our trial advocates for additional studies with other chemotherapy combinations.

Focused ultrasound-mediated small-molecule delivery to potentiate immune checkpoint blockade in solid tumors

In the last decade, immune checkpoint blockade (ICB) has revolutionized the standard of treatment for solid tumors. Despite success in several immunogenic tumor types evidenced by improved survival, ICB remains largely unresponsive, especially in "cold tumors" with poor lymphocyte infiltration. In addition, side effects such as immune-related adverse events (irAEs) are also obstacles for the clinical translation of ICB. Recent studies have shown that focused ultrasound (FUS), a non-invasive technology proven to be effective and safe for tumor treatment in clinical settings, could boost the therapeutic effect of ICB while alleviating the potential side effects. Most importantly, the application of FUS to ultrasound-sensitive small particles, such as microbubbles (MBs) or nanoparticles (NPs), allows for precise delivery and release of genetic materials, catalysts and chemotherapeutic agents to tumor sites, thus enhancing the anti-tumor effects of ICB while minimizing toxicity. In this review, we provide an updated overview of the progress made in recent years concerning ICB therapy assisted by FUS-controlled small-molecule delivery systems. We highlight the value of different FUS-augmented small-molecules delivery systems to ICB and describe the synergetic effects and underlying mechanisms of these combination strategies. Furthermore, we discuss the limitations of the current strategies and the possible ways that FUS-mediated small-molecule delivery systems could boost novel personalized ICB treatments for solid tumors.

Cardiotoxicity from neoadjuvant targeted treatment for breast cancer prior to surgery

Cancer treatment has been gradually shifting from non-specific cytotoxic agents to molecularly targeted drugs. Breast cancer (BC), a malignant tumor with one of the highest incidence worldwide, has seen a rapid development in terms of targeted therapies, leading to a radical change in the treatment paradigm. However, the use of targeted drugs is accompanied by an increasing rate of deaths due to non-tumor-related causes in BC patients, with cardiovascular complications as the most common cause. Cardiovascular toxicity during antitumor therapy has become a high-risk factor for survival in BC patients. Targeted drug-induced cardiotoxicity exerts a wide range of effects on cardiac structure and function, including conduction disturbances, QT interval prolongation, impaired myocardial contractility, myocardial fibrosis, and hypertrophy, resulting in various clinical manifestations, e.g., arrhythmias, cardiomyopathy, heart failure, and even sudden death. In adult patients, the incidence of antitumor targeted drug-induced cardiotoxicity can reach 50%, and current preclinical evaluation tools are often insufficiently effective in predicting clinical cardiotoxicity. Herein, we reviewed the current status of the occurrence, causative mechanisms, monitoring methods, and progress in the prevention and treatment of cardiotoxicity associated with preoperative neoadjuvant targeted therapy for BC. It supplements the absence of relevant review on the latest research progress of preoperative neoadjuvant targeted therapy for cardiotoxicity, with a view to providing more reference for clinical treatment of BC patients.

Emerging strategies: PARP inhibitors in combination with immune checkpoint blockade in BRCA1 and BRCA2 mutation-associated and triple-negative breast cancer

Poly (adenosine diphosphate-ribose) polymerase (PARP) inhibitor monotherapy in germline BRCA1 and BRCA2 mutation-associated metastatic breast cancer is a well-tolerated and an effective therapeutic strategy, however, the durability of response can be limited. Checkpoint inhibitors targeting the PD-1/PD-L1 axis as monotherapy in metastatic triple-negative breast cancer (mTNBC) have a limited role due to low response rates, but are capable of long, durable responses. Combination PARP inhibition with checkpoint blockade is an emerging area of investigation with potential synergy to produce robust responses with durability. Mechanistically, PARP inhibition activates the stimulator of interferon gene (STING) pathway to promote dendritic cell and T lymphocyte recruitment, increases tumor neoantigens, and upregulates PD-L1 expression to increase the immunogenicity of the tumor and thereby potentially enhance responses to immunotherapy. Several clinical trials have reported early results on PARP inhibitor and PD-1/PD-L1 checkpoint inhibitor combinations. All studies have shown safety and tolerability of this combination regimen. In advanced breast cancer associated with a germline BRCA1 or BRCA2 mutation, response rates have been high and similar to what is observed with PARP inhibitor monotherapy. Additional follow-up is needed to see if combination with a checkpoint inhibitor can lead to a clinically meaningful extension of durability of response in patients with germline mutations in BRCA1 and BRCA2. In unselected mTNBC in the 1st-3rd line setting, response rates of combined PARP inhibitor and PD-1/PD-L1 inhibitors have ranged from 18-21%, with higher rates of response among those with alterations in homologous recombination DNA repair pathway genes. Multiple ongoing studies will report additional data on combinations of PARP inhibitors and checkpoint blockade in the future and this combination strategy remains an active area of investigation.

Clonogenicity-based radioresistance determines the expression of immune suppressive immune checkpoint molecules after hypofractionated irradiation of MDA-MB-231 triple-negative breast cancer cells

Only a subset of patients with triple-negative breast cancer (TNBC) benefits from a combination of radio- (RT) and immunotherapy. Therefore, we aimed to examine the impact of radioresistance and brain metastasizing potential on the immunological phenotype of TNBC cells following hypofractionated RT by analyzing cell death, immune checkpoint molecule (ICM) expression and activation of human monocyte-derived dendritic cells (DCs). MDA-MB-231 triple-negative breast cancer tumor cells were used as model system. Apoptosis was the dominant cell death form of brain metastasizing tumor cells, while Hsp70 release was generally significantly increased following RT and went along with necrosis induction. The ICMs PD-L1, PD-L2, HVEM, ICOS-L, CD137-L and OX40-L were found on the tumor cell surfaces and were significantly upregulated by RT with 5 x 5.2 Gy. Strikingly, the expression of immune suppressive ICMs was significantly higher on radioresistant clones compared to their respective non-radioresistant ones. Although hypofractionated RT led to significant cell death induction and release of Hsp70 in all tumor cell lines, human monocyte-derived DCs were not activated after co-incubation with RT-treated tumor cells. We conclude that radioresistance is a potent driver of immune suppressive ICM expression on the surface of TNBC MDA-MB-231 cells. This mechanism is generally known to predominantly influence the effector phase, rather than the priming phase, of anti-tumor immune responses.

Immune-Checkpoint Inhibitors: A New Line of Attack in Triple-Negative Breast Cancer

Poor prognosis is a distinctive feature of triple-negative breast cancer (TNBC). Chemotherapy has long represented the main and unique treatment for patients with TNBC. Recently, immune checkpoint inhibitors (ICIs) were investigated in several clinical trials and were approved for clinical use in TNBC patients that express programmed cell death protein-1 (PD-1) in combination with chemotherapy in the first-line setting. ICIs are also being investigated in the neoadjuvant and adjuvant settings for TNBC. This chapter aims to discuss different ICIs used to treat all TNBC stages to date.

Spontaneous, naturally occurring cancers in non-human primates as a translational model for cancer immunotherapy

The complexity of cancer immunotherapy (CIT) demands reliable preclinical models to successfully translate study findings to the clinics. Non-human primates (NHPs; here referring to rhesus and cynomolgus macaques) share broad similarities with humans including physiology, genetic homology, and importantly also immune cell populations, immune regulatory mechanisms, and protein targets for CIT. Furthermore, NHP naturally develop cancers such as colorectal and breast cancer with an incidence, pathology, and age pattern comparable to humans. Thus, these tumor-bearing monkeys (TBMs) have the potential to bridge the experimental gap between early preclinical cancer models and patients with human cancer.This review presents our current knowledge of NHP immunology, the incidence and features of naturally-occurring cancers in NHP, and recent TBM trials investigating CIT to provide a scientific rationale for this unique model for human cancer.

Antitumor effect of CAR-T cells targeting transmembrane tumor necrosis factor alpha combined with PD-1 mAb on breast cancers

BACKGROUND

Our previous study showed that transmembrane tumor necrosis factor alpha (tmTNF-α) is overexpressed in primary breast cancers including triple-negative breast cancers (TNBCs). Chimeric antigen receptor engineered-T (CAR-T) cells have been successfully used mainly in B-cell malignancies.

METHODS

We generated CAR-T cells targeting tmTNF-α but not secreted tumor necrosis factor alpha and assessed the antitumor effect of the CAR-T cells on tmTNF-α-expressing breast cancer cells in vitro and in vivo.

RESULTS

Our tmTNF-α CAR-T cells showed potent cytotoxicity against tmTNF-α-expressing breast cancer cells but not tmTNF-α-negative tumor cells with increased secretion of interferon gamma (IFN-γ) and interleukin (IL)-2 in vitro. In tmTNF-α-overexpressing TNBC-bearing mice, the tmTNF-α CAR-T therapy induced evident tumor regression, prolonged survival and increased serum concentrations of IFN-γ and IL-2. However, we found thattmTNF-α induced programmed death-ligand 1 (PD-L1) expression through the p38 pathway via TNF receptor (TNFR) and through the NF-κB and AKT pathways via outside-to-inside (reverse) signaling, which might limit the efficacy of the CAR-T cell therapy. Blockage of the PD-L1/programmed death-1 (PD-1) pathway by PD-1 monoclonal antibody significantly enhanced the antitumor effect of the tmTNF-α CAR-T cell therapy in vitro and in vivo, and the combination was effective for antiprimary tumors and had a tendency to increase the antimetastasis effect of the CAR-T cell therapy.

CONCLUSION

Our findings suggest a potent antitumor efficacy of the tmTNF-α CAR-T cells that can be enhanced by anti-PD-L1/PD-1 because high PD-L1 expression in TNBC was induced by the tmTNF-α signaling, indicating a promising individual therapy for tmTNF-α-positive breast cancers including TNBC.

High VISTA expression is linked to a potent epithelial-mesenchymal transition and is positively correlated with PD1 in breast cancer

Breast cancer is the most common type of tumor in women worldwide. Immune checkpoint inhibitors, particularly anti-PDL1, have shown promise as a therapeutic approach for managing this disease. However, this type of immunotherapy still fails to work for some patients, leading researchers to explore alternative immune checkpoint targets. The Ig suppressor of T cell activation domain V (VISTA) has emerged as a novel immune checkpoint that delivers inhibitory signals to T cells and has demonstrated encouraging results in various cancers. Our study investigated the association of VISTA expression with clinicopathological parameters in breast cancer patients, its involvement in the Epithelial-Mesenchymal-Transition (EMT) process, and its correlation with PD1 expression. Transcriptomic analysis revealed that VISTA was associated with lobular and metaplastic histological type, tumor size, lymph node status, ER and PR negative status, and the TNBC molecular subtype. Furthermore, VISTA expression was strongly associated with an immunosuppressive tumor microenvironment. Immunohistochemistry analysis corroborated the transcriptomic results, indicating that VISTA was expressed in most immune cells (94%) and was significantly expressed in breast cancer tumor cells compared to matched adjacent tissues. Our study also showed for the first time that VISTA overexpression in breast cancer cells could be associated with the EMT process. Additionally, we identified a positive correlation between VISTA and PD-1 expression. Together, these results highlight the immunosuppressive effect of VISTA in breast cancer patients and suggest that bi-specific targeting of VISTA and PD-1 in combination therapy could be beneficial for these patients.

Advances in the structural characterization of complexes of therapeutic antibodies with PD-1 or PD-L1

Antibody-based immune checkpoint blockade (ICB)-based therapeutics have become effective clinical applications for cancers. Applications of monoclonal antibodies (mAbs) to de-activate the PD-1-PD-L1 pathway could effectively reverse the phenotype of depleted activated thymocytes (T cells) to recover their anti-tumoral activities. High-resolution structures of the complexes of the therapeutic monoclonal antibodies with PD-1 or PD-L1 have revealed the key inter-molecular interactions and provided valuable insights into the fundamental mechanisms by which these antibodies inhibit PD-L1-PD-1 binding. Each anti-PD-1 mAb exhibits a unique blockade mechanism, such as interference with large PD-1-PD-L1 contacting interfaces, steric hindrance by overlapping a small area of this site, or binding to an N-glycosylated site. In contrast, all therapeutic anti-PD-L1 mAbs bind to a similar area of PD-L1. Here, we summarized advances in the structural characterization of the complexes of commercial mAbs that target PD-1 or PD-L1. In particular, we focus on the unique characteristics of those mAb structures, epitopes, and blockade mechanisms. It is well known that the use of antibodies as anti-tumor drugs has increased recently and both PD-1 and PD-L1 have attracted substantial attention as target for antibodies derived from new technologies. By focusing on structural characterization, this review aims to aid the development of novel antibodies targeting PD-1 or PD-L1 in the future.

Radiomic models based on magnetic resonance imaging predict the spatial distribution of CD8+ tumor-infiltrating lymphocytes in breast cancer

Infiltration of CD8⁺ T cells and their spatial contexture, represented by immunophenotype, predict the prognosis and therapeutic response in breast cancer. However, a non-surgical method using radiomics to evaluate breast cancer immunophenotype has not been explored. Here, we assessed the CD8⁺ T cell-based immunophenotype in patients with breast cancer undergoing upfront surgery (n = 182). We extracted radiomic features from the four phases of dynamic contrast-enhanced magnetic resonance imaging, and randomly divided the patients into training (n = 137) and validation (n = 45) cohorts. For predicting the immunophenotypes, radiomic models (RMs) that combined the four phases demonstrated superior performance to those derived from a single phase. For discriminating the inflamed tumor from the non-inflamed tumor, the feature-based combination model from the whole tumor (RM-whole_FC) showed high performance in both training (area under the receiver operating characteristic curve [AUC] = 0.973) and validation cohorts (AUC = 0.985). Similarly, the feature-based combination model from the peripheral tumor (RM-peri_FC) discriminated between immune-desert and excluded tumors with high performance in both training (AUC = 0.993) and validation cohorts (AUC = 0.984). Both RM-whole_FC and RM-peri_FC demonstrated good to excellent performance for every molecular subtype. Furthermore, in patients who underwent neoadjuvant chemotherapy (n = 64), pre-treatment images showed that tumors exhibiting complete response to neoadjuvant chemotherapy had significantly higher scores from RM-whole_FC and lower scores from RM-peri_FC. Our RMs predicted the immunophenotype of breast cancer based on the spatial distribution of CD8⁺ T cells with high accuracy. This approach can be used to stratify patients non-invasively based on the status of the tumor-immune microenvironment.