Effect of Eribulin With or Without Pembrolizumab on Progression-Free Survival for Patients With Hormone Receptor-Positive, ERBB2-Negative Metastatic Breast Cancer: A Randomized Clinical Trial

Evaluation of time-to-onset and outcome of cardiac adverse events related to pembrolizumab using post-marketing surveillance in Japanese patients

BACKGROUND

Pembrolizumab has been widely used in patients since its release, but information on cardiac Adverse Events (AEs) related to pembrolizumab remains lacking, particularly in Japanese populations.

OBJECTIVES

This study aims to evaluate time to onset, incidence rates, and outcomes for pembrolizumab-induced cardiac AEs in patients with cancer using the Japanese Adverse Drug Event Report database.

METHODS

We analysed data for the period from April 2004 to March 2022. Data on cardiac AEs were extracted and relative risks of AEs were estimated using the reporting odds ratio.

RESULTS

We analysed 2,021,907 reports and identified 15,306 reports of AEs caused by pembrolizumab. Of these, 399 cardiac AEs were associated with pembrolizumab. Signals were detected for six cardiac AEs: myocarditis, immune-mediated myocarditis, pericardial effusion, cardiac tamponade, pericarditis, and pericarditis malignant. A histogram of median times to onset showed occurrence from 33 (21-97) days for immune-mediated myocarditis to 138 (67-168) days for pericarditis malignant, but some cases occurred even more than 1 year after the start of administration. Among these, myocarditis was the most frequently reported (27.1%), with fatal cases also reported.

CONCLUSION

This study focused on cardiac AEs caused by pembrolizumab as post-marketing AEs. Patients should be monitored not only at the time of administration, but also over time for signs of these AEs, especially myocarditis, as some patients may have serious outcomes.

Incidence of thyroid dysfunction caused by immune checkpoint inhibitors combined with chemotherapy: A systematic review and meta-analysis

BACKGROUND

The combination of immune checkpoint inhibitors (ICIs) and chemotherapy as a first-line treatment for triple-negative breast cancer (TNBC) has been associated with many adverse reactions. Thyroid dysfunction, the most common adverse reaction of the endocrine system, has also attracted significant attention. This study aimed to analyse the effect of ICIs combined with chemotherapy on thyroid function in patients with TNBC.

METHODS

As of November 4, 2023, we searched the PubMed, Web of Science, and Cochrane Library databases for clinical trials of ICIs combined with chemotherapy for the treatment of TNBC. The incidence of hypothyroidism and hyperthyroidism was calculated using a random-effects model.

RESULTS

In the final analysis, 3,226 patients from 19 studies were included. The total incidence of all-grade hypothyroidism induced by the combination of ICIs and chemotherapy in treating TNBC (12% (95% confidence intervals(CI): 0.10-0.15)) was higher than that of hyperthyroidism (5% (95% CI: 0.04-0.06)). Pembrolizumab combined with chemotherapy caused the highest incidence of all grades of hypothyroidism for 13% (95% CI: 0.05-0.06). Durvalumab combined with chemotherapy caused the highest incidence of all grades of hyperthyroidism, at 7% (95% CI: 0.03-0.11). ICIs combined with chemotherapy caused a higher incidence of all grades of hypothyroidism in advanced TNBC (15% (95% CI: 0.13-0.17)) than in early stage TNBC (10% (95% CI: 0.07-0.13)).

CONCLUSION

In TNBC, the incidence of hypothyroidism caused by the combination of ICIs and chemotherapy was significantly higher than that caused by hyperthyroidism. Pembrolizumab combined with chemotherapy resulted in the highest incidence of hypothyroidism. The incidence of hypothyroidism in patients with advanced TNBC was significantly higher than that in patients with early stage TNBC. In addition, ICIs combined with chemotherapy resulted in 16 out of 3,226 patients experiencing grade ≥ 3 thyroid dysfunction. Although the incidence of severe thyroid dysfunction is low, it requires attention.

PROSPERO

CRD42023477933.

Progesterone receptor impairs immune respond and down-regulates sensitivity to anti-LAG3 in breast cancer

BACKGROUND

Progesterone receptor (PR) serves as a crucial prognostic and predictive marker in breast cancer. Nonetheless, the interplay between PR and the tumor immune microenvironment remains inadequately understood. This investigation employs bioinformatics analyses, mouse models, and clinical specimens to elucidate the impact of PR on immune microenvironment and identify potential targets for immunotherapy, furnishing valuable guidance for clinical practice.

METHODS

Analysis of immune infiltration score by Xcell between PR-positive and PR-negative breast cancer tumors. Construction of overexpression mouse progesterone receptor (mPgr) EMT-6 cell was to explore the tumor immune microenvironment. Furthermore, anti- Lymphocyte-activation gene 3 (LAG3) therapy aimed to investigate whether PR could influence the effectiveness of immune treatments.

RESULTS

Overexpression mPgr inhibited tumor growth in vitro, but promoted tumor growth in Balb/c mouse. Flow cytometry showed that the proportion and cytotoxicity of CD8+T cells in tumor of overexpressing mPgr group were significantly reduced. The significant reduction in overexpressing mPgr group was found in the proportions of LAG3+CD8+ T cells and LAG3+ Treg T cells. Anti-LAG3 treatment resulted in reduced tumor growth in EV group mouse rather than in overexpressing mPgr group. Patents derived tumor fragment (PDTF) also showed higher anti-tumor ability of CD3+T cell in patents' tumor with PR <20% after anti-human LAG3 treatment in vitro.

CONCLUSIONS

The mPgr promotes tumor growth by downregulating the infiltration and function of cytotoxic cell. LAG3 may be a target of ER-positive breast cancer immunotherapy. The high expression of PR hinders the sensitivity to anti-LAG3 treatment.

Efficacy and safety of eribulin mesylate in patients with locally advanced or metastatic breast cancer previously treated with anthracycline/taxanes

BACKGROUND

This prospective real-world study aimed to assess the efficacy and safety of eribulin in the clinical practice against advanced breast cancer (ABC) in China.

PATIENTS AND METHODS

In this study, eligible patients with inoperable locally advanced or metastatic breast cancer who had experienced prior neo-/adjuvant or failed the palliative treatment with anthracycline/taxanes were included. Eribulin (1.4 mg/m2) was infused intravenously on Day 1 and Day 8 every 3 weeks until disease progression or intolerable toxicity occurred. The progression-free survival (PFS), overall response rate (ORR), disease control rate (DCR), and safety of the treatment were assessed.

RESULTS

One hundred and thirty-four patients were enrolled. The median PFS (mPFS) was 4.3 months (95% CI: 0.3-15.4). The ORR and DCR was 32.1% and 79.1%, respectively. The mPFS of patients who received eribulin as first- or second-line treatment was significantly better than those who received eribulin as ≥3-line treatment (6.9 months [95% CI: 3.2-8.8] vs. 4.0 months [95% CI: 3.4-4.6], p = 0.006). The mPFS of patients with triple-negative, HER2-positive, and HER2(-)/HR(+) was 3.4 (95% CI: 2.7-4.1), 6.2 (95% CI: 2.3-10.1) and 5.0 months (95% CI: 4.1-5.9), respectively. HER2(+) patients had significantly longer PFS than TNBC patients (p = 0.022). Patients received combination therapy had a significantly longer mPFS than those who received eribulin monotherapy (5.0 months [95% CI 3.6-6.3] vs. 4.0 months [95% CI: 3.3-4.7] [p = 0.016]). Multivariate analysis revealed that MBC patients with a molecular typing of non-TNBC receiving eribulin as ≤2-line therapy and combination therapy had a low risk of disease progression. Neutropenia (33.58%), leukopenia (11.94%), and thrombocytopenia (4.48%) were the most common treatment-related adverse events.

CONCLUSION

Eribulin demonstrated effective clinical activity and a favorable tolerability profile in Chinese patients with ABC in the real-world. The efficacy and safety profile were consistent with those reported in previous randomized phase 3 trials.

Expert consensus on the clinical application of immunotherapy in breast cancer: 2024

Background

Significant progress has been made in immunotherapy of breast cancer (BC) with the approval of multiple immune checkpoint inhibitors (ICIs), particularly in early and metastatic triple-negative breast cancer (TNBC) settings. Most guidelines have recommended immune therapy as the important approach in BC, yet several critical aspects still require further clarification, including proper patient selection, treatment duration, optimized chemotherapy partner, predictive biomarkers, and specific considerations for Chinese patients.

Methods

(I) Establishment of expert group: the expert group consists of 32 experts from departments such as medical oncology, breast surgery, and pathology; (II) literature search: mainly conducted in English databases (such as PubMed, Embase, and Cochrane Library) and Chinese databases (such as China National Knowledge Infrastructure, China Biology Medicine disc, and Wanfang Database), with a search cutoff date of April 23, 2024; (III) assessment of evidence quality and recommendation strength: evidence quality and recommendation opinions are graded based on the evidence category and recommendation level of the Chinese Society of Clinical Oncology (CSCO) guidelines; (IV) consensus formulation: on the March 2, 2024, through online consensus meeting, the consensus content is thoroughly discussed, and opinions from all experts are solicited.

Results

The consensus meeting has resulted in 15 detailed recommendations, providing clearer guidance on the clinical application of immunotherapy in BC management. The core suggestions are as follows: for early-stage II-III TNBC and metastatic TNBC (mTNBC) in the first-line setting, programmed cell death protein 1 (PD-1) inhibitors can be considered. However, for hormone receptor-positive/human epidermal growth factor receptor 2-negative BC (HR+/HER2- BC), HER2+ BC, and mTNBC in later lines of therapy, evidence is lacking to support the use of immunotherapy.

Conclusions

This consensus provides a comprehensive overview of BC immunotherapy, including immunotherapy for early-stage BC and late-stage BC, immune related adverse event (irAE) management, biomarkers of immunotherapy, and future directions. The consensus consolidates these deliberations into 15 evidence-based recommendations, serving as a practical guide for clinicians to more scientifically and systematically manage the clinical application of immunotherapy.

Efficacy and safety of a combination treatment of immune checkpoint inhibitors in metastatic breast cancer: a systematic review and meta-analysis

PURPOSE

Immune checkpoint inhibitors (ICIs) in combination with chemotherapy have showed its benefits in clinical studies, and here we conducted a further evaluation on the safety and efficacy of this treatment strategy.

METHODS

A systematic literature review was conducted in PubMed, Embase and Cochrane Library to identify clinical studies on ICIs and chemotherapy for metastatic breast cancer. The primary efficacy endpoints were progression-free survival (PFS) and overall survival (OS), and adverse events (AEs) were analyzed. Random or fixed effects models were used to estimate pooled Hazard ratio (HR), odds ratio (OR) and the data of 95% confidence interval (CI) depend on the Heterogeneity. Cochrane risk assessment tool was used to assess risk of bias. We also drew forest plots and funnel plots, respectively.

RESULTS

Seven studies with intend-to-treat (ITT) population for 3255 patients were analyzed. ICIs pooled therapy showed clinical benefits compared with chemotherapy alone, improving PFS (HR = 0.81, 95% CI: 0.74-0.90) of patients with metastatic triple negative breast cancer (mTNBC), especially in patients with PD-L1-positive tumors. However, it had no effect on OS (HR = 0.92, 95% CI 0.85-1.01). Besides, mTNBC patients received pooled therapy were less frequently to have AEs (OR = 1.30, 95% CI: 1.09-1.54). In patients with metastatic Human Epidermal Growth Factor Receptor 2 (HER2) negative breast cancer, pooled therapy showed no benefit for PFS (HR = 0.80, 95% CI: 0.50-1.28) and OS (HR = 0.87, 95% CI: 0.48-1.58).

CONCLUSION

Pooled therapy had improved PFS in mTNBC patients, especially in patients with PD-L1-positive tumors, and it was less likely to cause grade ≥ 3 AEs.

Risk of interstitial lung disease with the use of programmed cell death 1 (PD-1) inhibitor compared with programmed cell death ligand 1 (PD-L1) inhibitor in patients with breast cancer: A systematic review and meta-analysis

Background

Programmed cell death 1 (PD-1) and programmed cell death ligand 1 (PD-L1) inhibitors have become integral elements within the current landscape of breast cancer treatment modalities; however, they are associated with interstitial lung disease (ILD), which is rare but potentially fatal. Notably, only a few studies have compared the difference in ILD incidence between PD-1 and PD-L1 inhibitors. Therefore, this study aimed to assess the discrepancies regarding ILD risk between the two immune checkpoint inhibitors. We also reported three cases of ILD after PD-1 inhibitor treatment.

Methods

We comprehensively searched PubMed, EMBASE, and the Cochrane Library to identify clinical trials that investigated PD-1/PD-L1 inhibitor treatment for patients with breast cancer. Pooled overall estimates of incidence and risk ratio (RR) were calculated with a 95% confidence interval (CI), and a mirror group analysis was performed using eligible studies.

Results

This meta-analysis included 29 studies with 4639 patients who received PD-1/PD-L1 inhibitor treatment. A higher ILD incidence was observed among 2508 patients treated with PD-1 inhibitors than among 2131 patients treated with PD-L1 inhibitors (0.05 vs. 0.02). The mirror group analysis further revealed a higher ILD event risk in patients treated with PD-1 inhibitors than in those treated with PD-L1 inhibitors (RR = 2.34, 95% CI, 1.13-4.82, P = 0.02).

Conclusion

Our findings suggest a greater risk of ILD with PD-1 inhibitors than with PD-L1 inhibitors. These findings are instrumental for clinicians in treatment deliberations, and the adoption of more structured diagnostic approaches and management protocols is necessary to mitigate the risk of ILD.

PACE: A Randomized Phase II Study of Fulvestrant, Palbociclib, and Avelumab After Progression on Cyclin-Dependent Kinase 4/6 Inhibitor and Aromatase Inhibitor for Hormone Receptor-Positive/Human Epidermal Growth Factor Receptor-Negative Metastatic Breast Cancer

PURPOSE

Cyclin-dependent kinase (CDK) 4/6 inhibitors (CDK4/6is) are an important component of treatment for hormone receptor-positive/human epidermal growth factor receptor 2-negative (HER2-) metastatic breast cancer (MBC), but it is not known if patients might derive benefit from continuation of CDK4/6i with endocrine therapy beyond initial tumor progression or if the addition of checkpoint inhibitor therapy has value in this setting.

METHODS

The randomized multicenter phase II PACE trial enrolled patients with hormone receptor-positive/HER2- MBC whose disease had progressed on previous CDK4/6i and aromatase inhibitor (AI) therapy. Patients were randomly assigned 1:2:1 to receive fulvestrant (F), fulvestrant plus palbociclib (F + P), or fulvestrant plus palbociclib and avelumab (F + P + A). The primary end point was investigator-assessed progression-free survival (PFS) in patients treated with F versus F + P.

RESULTS

Overall, 220 patients were randomly assigned between September 2017 and February 2022. The median age was 57 years (range, 25-83 years). Most patients were postmenopausal (80.9%), and 40% were originally diagnosed with de novo MBC. Palbociclib was the most common previous CDK4/6i (90.9%). The median PFS was 4.8 months on F and 4.6 months on F + P (hazard ratio [HR], 1.11 [90% CI, 0.79 to 1.55]; P = .62). The median PFS on F + P + A was 8.1 months (HR v F, 0.75 [90% CI, 0.50 to 1.12]; P = .23). The difference in PFS with F + P and F + P + A versus F was greater among patients with baseline ESR1 and PIK3CA alterations.

CONCLUSION

The addition of palbociclib to fulvestrant did not improve PFS versus fulvestrant alone among patients with hormone receptor-positive/HER2- MBC whose disease had progressed on a previous CDK4/6i plus AI. The increased PFS seen with the addition of avelumab warrants further investigation in this patient population.

Durvalumab and tremelimumab before surgery in patients with hormone receptor positive, HER2-negative stage II-III breast cancer

A clinical trial was conducted to assess the feasibility of enrolling patients with Stage II or III hormone receptor positive (HR+)/HER2-negative breast cancer to pre-operative dual PD-L1/CTLA-4 checkpoint inhibition administered prior to neoadjuvant chemotherapy (NACT). Eight eligible patients were treated with upfront durvalumab and tremelimumab for two cycles. Patients then received NACT prior to breast surgery. Seven patients had baseline and interval breast ultrasounds after combination immunotherapy and the responses were mixed: 3/7 patients experienced a ≥30% decrease in tumor volume, 3/7 a ≥30% increase, and 1 patient had stable disease. At the time of breast surgery, 1/8 patients had a pathologic complete response (pCR). The trial was stopped early after 3 of 8 patients experienced immunotherapy-related toxicity or suspected disease progression that prompted discontinuation or a delay in the administration of NACT. Two patients experienced grade 3 immune-related adverse events (1 with colitis, 1 with endocrinopathy). Analysis of the tumor microenvironment after combination immunotherapy did not show a significant change in immune cell subsets from baseline. There was limited benefit for dual checkpoint blockade administered prior to NACT in our study of 8 patients with HR+/HER2-negative breast cancer.

PD-1/PD-L1 Inhibitor - Related Adverse Events and Their Management in Breast Cancer

As the positive results of multiple clinical trials were released, the Programmed cell death 1 (PD-1) and Programmed cell death ligand 1 (PD-L1) inhibitors emerge as the focus of integrative breast cancer treatment. PD-1/PD-L1 inhibitors are often used as a sequential agent to be combined with other agents such as chemotherapeutic agents, targeted agents, and radiation therapy. As multiple therapies are administered simultaneously or in sequence, they are prone to a variety of adverse effects on patients while achieving efficacy. It is a challenge for clinicians to maintaining the balance between immune-related adverse effects(irAEs) and treatment efficacy. Previous literatures have paid lots of attention on the adverse effects caused by immunosuppressive agents themselves, while there is a dearth of the research on the management of adverse immune effects during the combination of immunotherapy with other treatments. In this review, we discuss the overall incidence of irAEs caused by PD-1/PD-L1 inhibitors in combination with various types of treatments in breast cancer, including chemotherapy, CTLA-4 inhibitors, targeted therapy, and radiotherapy, and systematically summarizes the clinical management to each organ-related adverse immune reaction. It is important to emphasize that in the event of irAEs such as neurological, hematologic, and cardiac toxicity, there is no alternative treatment but to terminate immunotherapy. Thus, seeking more effective strategy of irAEs' management is imminent and clinicians are urged to raise the awareness of the management of adverse immune reactions.

Update on current and new potential immunotherapies in breast cancer, from bench to bedside

Impressive advances have been seen in cancer immunotherapy during the last years. Although breast cancer (BC) has been long considered as non-immunogenic, immunotherapy for the treatment of BC is now emerging as a new promising therapeutic approach with considerable potential. This is supported by a plethora of completed and ongoing preclinical and clinical studies in various types of immunotherapies. However, a significant gap between clinical oncology and basic cancer research impairs the understanding of cancer immunology and immunotherapy, hampering cancer therapy research and development. To exploit the accumulating available data in an optimal way, both fundamental mechanisms at play in BC immunotherapy and its clinical pitfalls must be integrated. Then, clinical trials must be critically designed with appropriate combinations of conventional and immunotherapeutic strategies. While there is room for major improvement, this updated review details the immunotherapeutic tools available to date, from bench to bedside, in the hope that this will lead to rethinking and optimizing standards of care for BC patients.

Immune-related cardiovascular toxicities of PD-1/PD-L1 inhibitors in solid tumors: an updated systematic review and meta-analysis

Purpose

The objective of this study was to investigate the risk of cardiovascular toxicities related to PD-1/PD-L1 inhibitors in solid tumors.

Methods

A literature search was performed following the participants, interventions, comparisons, outcomes, and study design (PICOS) principles, and the study adhered to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Data analysis was conducted using Review Manager version 5.4.

Results

This meta-analysis included 69 randomized controlled trials (RCTs) divided into five groups based on the treatment regimens: PD-1/PD-L1 + chemotherapy versus chemotherapy, PD-1/PD-L1 versus chemotherapy, PD-1/PD-L1 versus placebo, PD-1/PD-L1 + CTLA-4 versus PD-1/PD-L1 and PD-1/PD-L1 + CTLA-4 versus chemotherapy. Compared to chemotherapy treatment alone, PD-1/PD-L1 +chemotherapy significantly increased the risk of hypertension [all-grade (OR = 1.27, 95% CI [1.05, 1.53], p = 0.01); grade 3-5 (OR = 1.36, 95% CI [1.04, 1.79], p = 0.03)], hypotension [all-grade (OR = 2.03, 95% CI [1.19, 3.45], p = 0.009); grade 3-5 (OR = 3.60, 95% CI [1.22, 10.60], p = 0.02)], arrhythmia [all-grade (OR = 1.53, 95% CI [1.02, 2.30], p = 0.04); grade 3-5 (OR = 2.91, 95% CI [1.33, 6.39], p = 0.008)] and myocarditis [all-grade (OR = 2.42, 95% CI [1.06, 5.54], p = 0.04)]. The risk of all-grade hypotension (OR = 2.87, 95% CI [1.26, 6.55], p = 0.01) and all-grade arrhythmia (OR = 2.03, 95% CI [1.13, 3.64], p = 0.02) significantly increased when treated with PD-1/PD-L1 inhibitors compared to the placebo. The risks of cardiovascular toxicities are significantly higher with PD-1+CTLA-4 compared to PD-1 alone (OR = 2.02, 95% CI [1.12, 3.66], p = 0.02).

Conclusion

PD-1/PD-L1 inhibitor leads to an increased risk of cardiovascular toxicities, especially hypertension, hypotension, arrhythmia, and myocarditis.

Ipilimumab and nivolumab combined with anthracycline-based chemotherapy in metastatic hormone receptor-positive breast cancer: a randomized phase 2b trial

BACKGROUND

Immune checkpoint inhibitors have shown minimal clinical activity in hormone receptor-positive metastatic breast cancer (HR+mBC). Doxorubicin and low-dose cyclophosphamide are reported to induce immune responses and counter regulatory T cells (Tregs). Here, we report the efficacy and safety of combined programmed cell death protein-1/cytotoxic T-lymphocyte-associated protein 4 blockade concomitant with or after immunomodulatory chemotherapy for HR+mBC.

METHODS

Patients with HR+mBC starting first-/second- line chemotherapy (chemo) were randomized 2:3 to chemotherapy (pegylated liposomal doxorubicin 20 mg/m2 every second week plus cyclophosphamide 50 mg by mouth/day in every other 2-week cycle) with or without concomitant ipilimumab (ipi; 1 mg/kg every sixth week) and nivolumab (nivo; 240 mg every second week). Patients in the chemo-only arm were offered cross-over to ipi/nivo without chemotherapy. Co-primary endpoints were safety in all patients starting therapy and progression-free survival (PFS) in the per-protocol (PP) population, defined as all patients evaluated for response and receiving at least two treatment cycles. Secondary endpoints included objective response rate, clinical benefit rate, Treg changes during therapy and assessment of programmed death-ligand 1 (PD-L1), mutational burden and immune gene signatures as biomarkers.

RESULTS

Eighty-two patients were randomized and received immune-chemo (N=49) or chemo-only (N=33), 16 patients continued to the ipi/nivo-only cross-over arm. Median follow-up was 41.4 months. Serious adverse events occurred in 63% in the immune-chemo arm, 39% in the chemo-only arm and 31% in the cross-over-arm. In the PP population (N=78) median PFS in the immune-chemo arm was 5.1 months, compared with 3.6 months in the chemo-only arm, with HR 0.94 (95% CI 0.59 to 1.51). Clinical benefit rates were 55% (26/47) and 48% (15/31) in the immune-chemo and chemo-only arms, respectively. In the cross-over-arm (ipi/nivo-only), objective responses were observed in 19% of patients (3/16) and clinical benefit in 25% (4/16). Treg levels in blood decreased after study chemotherapy. High-grade immune-related adverse events were associated with prolonged PFS. PD-L1 status and mutational burden were not associated with ipi/nivo benefit, whereas a numerical PFS advantage was observed for patients with a high Treg gene signature in tumor.

CONCLUSION

The addition of ipi/nivo to chemotherapy increased toxicity without improving efficacy. Ipi/nivo administered sequentially to chemotherapy was tolerable and induced clinical responses.

TRIAL REGISTRATION NUMBER

ClinicalTrials.gov Identifier: NCT03409198.

Clinical activity of nivolumab in combination with eribulin in HER2-negative metastatic breast cancer: A phase IB/II study (KCSG BR18-16)

AIM

We evaluated the efficacy and safety of nivolumab and eribulin combination therapy for metastatic breast cancer (BC) in Asian populations.

METHODS

In this parallel phase II study, adult patients with histologically confirmed recurrent/metastatic hormone receptor-positive/HER2-negative (HR+HER2-) or triple-negative BC (TNBC) were prospectively enroled from 10 academic hospitals in Korea (ClinicalTrials.gov Identifier: NCT04061863). They received nivolumab (360 mg) on day 1 plus eribulin (1.4 mg/m2) on days 1 and 8 every 3 weeks until disease progression or intolerable toxicity. The primary endpoint was the investigator-assessed 6-month progression-free survival (PFS) rate in each subtype. Secondary endpoints included investigator-assessed objective response rate (ORR) as per Response Evaluation Criteria in Advanced Solid Tumors version 1.1, disease control rate, overall survival, and treatment toxicity. The association between PD-L1 expression and efficacy was investigated.

RESULTS

Forty-five patients with HR+HER2- BC and 45 with TNBC were enroled. Their median age was 51 (range, 31-71) years, and 74 (82.2%) received one or two prior treatments before enrolment. Six-month PFS was 47.2% and 25.1% in the HR+HER2- and TNBC cohorts, respectively. Median PFS was 5.6 (95% confidence interval [CI]: 5.3-7.4) and 3.0 (95% CI: 2.1-5.2) months in the HR+HER2- and TNBC groups, respectively. ORRs were 53.3% (complete response [CR]: 0, partial response [PR]: 24) and 28.9% (CR: 1, PR: 12). Patients with PD-L1+ tumours (PD-L1 expression ≥1%) and PD-L1- tumours (ORR 50% versus 53.8% in HR+HER2-, 30.8% versus 29.0% in TNBC) had similar ORRs. Neutropenia was the most common grade 3/4 adverse event; the most common immune-related adverse events (AEs) were grades 1/2 hypothyroidism and pruritus. Five patients discontinued therapy because of immune-related AEs.

CONCLUSION

Nivolumab plus eribulin showed promising efficacy and tolerable safety in previously treated HER2- metastatic BC.

TRIAL REGISTRATION

NCT04061863.

Association of tumor-infiltrating lymphocytes with recurrence score in hormone receptor-positive/HER2-negative breast cancer: Analysis of four prospective studies

BACKGROUND

The clinical value of tumor infiltrating lymphocytes (TILs) in hormone receptor-positive (HR+)/HER2- breast cancer (BC) may be unearthed by focusing on more biologically aggressive tumors. Here we deepen and describe the correlation between RS and TILs, proposing an immuno-genomic model for HR+ /HER2- BC.

METHODS

We enrolled T1-T3, N0-N1 BC patients with available RS® and TILs in the context of four multicenter, prospective studies. RS® and TILs were considered as continuous and categorical variables. RS® was categorized into: 0-10 (low risk), 11-25 (intermediate risk) and 26-100 (high risk); TILs were categorized into: low TILs (0-10%), intermediate TILs (11-59%) and high TILs (60-100%).

RESULTS

811 patients were included. RS distribution was (n = 810): low risk 22.0%, intermediate risk 61.2%, high risk 16.8%. TIL distribution was (n = 455): low TILs 84.6%, intermediate TILs 13.6% and high TILs 1.8%. A significant, weak positive, linear correlation was found between continuous TILs and RS (Pearson coefficient=0.223, p < 0.001). When considering RS and TILs categories, tumors with intermediate/high TIL levels significantly enriched the high RS subgroup (p = 0.006). This was confirmed both within Luminal A and Luminal B cohorts. Among high-RS patients, 16.7% of Luminal A and 26.7% of Luminal B tumors had intermediate/high TILs.

CONCLUSIONS

We observed that RS® and TILs capture only slightly overlapping information on the biology of HR+ /HER2- tumor microenvironment. We demonstrated the feasibility of combining RS and TILs into a composite immuno-genomic model, which may serve the purpose of guiding and focalizing patient selection in the further development of immunotherapy strategies for Luminal-like disease.

Eribulin is an immune potentiator in breast cancer that upregulates human leukocyte antigen class I expression via the induction of NOD-like receptor family CARD domain-containing 5

Eribulin inhibits microtubule polymerization and improves the overall survival of patients with recurrent metastatic breast cancer. A subgroup analysis revealed a low neutrophil to lymphocyte ratio (NLR) (<3) to be a prognostic factor of eribulin treatment. We thus hypothesized that eribulin might be related to the immune response for breast cancer cells and we analyzed the effects of eribulin on the immune system. Immunohistochemical staining revealed that human leukocyte antigen (HLA) class I expression was increased in clinical samples after eribulin treatment. In vitro assays revealed that eribulin treatment increased HLA class I expression in breast cancer line cells. RNA-sequencing demonstrated that eribulin treatment increased the expression of the NOD-like family CARD domain-containing 5 (NLRC5), a master regulator of HLA class I expression. Eribulin treatment increased the NY-ESO-1-specific T-cell receptor (TCR) transduced T (TCR-T) cell response for New York oesophageal squamous cell carcinoma 1 (NY-ESO-1) overexpressed breast cancer cells. The eribulin and TCR-T combined therapy model revealed that eribulin and immunotherapy using TCR-T cells has a synergistic effect. In summary, eribulin increases the expression of HLA class 1 via HLA class 1 transactivatior NLRC5 and eribulin combination with immunotherapy can be effective for the treatment of breast cancer.

The trichotomy of HER2 expression confers new insights into the understanding and managing for breast cancer stratified by HER2 status

Human epidermal growth factor receptor 2 (HER2) is a tyrosine kinase receptor that plays a carcinogenic role in breast cancer (BC) through gene amplification, mutation, or overexpression. Traditional methods of HER2 detection were divided into positive (immunohistochemistry (IHC) 3+/fluorescence in situ hybridization (FISH) amplification) and negative (IHC 2+/FISH-, IHC 1+, IHC 0) according to the dichotomy method. Anti-HER2-targeted therapies, such as trastuzumab and pertuzumab, have significantly improved the prognosis of HER2-positive patients. However, up to 75% to 85% of patients remain HER2-negative. In recent years, with the rapid development of molecular biology, gene detection technology, targeted therapy, and immunotherapy, researchers have actively explored the clinicopathological characteristics, molecular biological characteristics, treatment methods, and HER2 detection methods of HER2-low/zero breast cancer. With the clinical efficacy of new anti-HER2 targeted drugs, accurate classification of breast cancer is very important for the treatment choice. Therefore, the following review summarizes the necessity of developing HER2 detection methods, and the clinicopathological and drug treatment characteristics of patients with HER2-low/zero, to light the dawn of the treatment of breast cancer patients with HER2-low/zero expression.

Recent Developments in the Therapeutic Landscape of Advanced or Metastatic Hormone Receptor-Positive Breast Cancer

Hormone receptor-positive (HR+) disease is the most frequently diagnosed subtype of breast cancer. Among tumor subtypes, natural course of HR+ breast cancer is indolent with favorable prognosis compared to other subtypes such as human epidermal growth factor protein 2-positive disease and triple-negative disease. HR+ tumors are dependent on steroid hormone signaling and endocrine therapy is the main treatment option. Recently, the discovery of cyclin-dependent kinase 4/6 inhibitors and their synergistic effects with endocrine therapy has dramatically improved treatment outcome of advanced HR+ breast cancer. The demonstrated efficacy of additional nonhormonal agents, such as targeted therapy against mammalian target of rapamycin and phosphatidylinositol 3-kinase signaling, poly(ADP-ribose) polymerase inhibitors, antibody-drug conjugates, and immunotherapeutic agents have further expanded the available therapeutic options. This article reviews the latest advancements in the treatment of HR+ breast cancer, and in doing so discusses not only the development of currently available treatment regimens but also emerging therapies that invite future research opportunities in the field.

Emerging systemic therapy options beyond CDK4/6 inhibitors for hormone receptor-positive HER2-negative advanced breast cancer

Endocrine therapy (ET) with cyclin-dependent kinase 4/6 inhibitor (CDK4/6i) is currently the standard first-line treatment for most patients with hormone receptor (HR) positive, human epidermal growth factor receptor (HER2) negative advanced breast cancer. However, resistance to ET and CDK4/6i inevitably ensues. The optimal post-progression treatment regimens and their sequencing continue to evolve in the rapidly changing treatment landscape. In this review, we summarize the mechanisms of resistance to ET and CDK4/6i, which can be broadly classified as alterations affecting cell cycle mediators and activation of alternative signaling pathways. Recent clinical trials have been directed at the targets and pathways implicated, including estrogen and androgen receptors, PI3K/AKT/mTOR and MAPK pathways, tyrosine kinase receptors such as FGFR and HER2, homologous recombination repair pathway, other components of the cell cycle and cell death. We describe the findings from these clinical trials using small molecule inhibitors, antibody-drug conjugates and immunotherapy, providing insights into how these novel strategies may circumvent treatment resistance, and discuss how some have not translated into clinical benefit. The challenges posed by tumor heterogeneity, adaptive rewiring of signaling pathways and dose-limiting toxicities underscore the need to elucidate the latest tumor biology in each patient, and develop treatments with improved therapeutic index in the era of precision medicine.

Systemic therapy for hormone receptor-positive/human epidermal growth factor receptor 2-negative early stage and metastatic breast cancer

Hormone receptor (HR)-positive and human epidermal growth factor receptor 2 (HER2)-negative breast cancer is defined by the presence of the estrogen receptor and/or the progesterone receptor and the absence of HER2 gene amplification. HR-positive/HER2-negative breast cancer accounts for 65%-70% of all breast cancers, and incidence increases with increasing age. Treatment varies by stage, and endocrine therapy is the mainstay of treatment in both early stage and late-stage disease. Combinations with cyclin-dependent kinase 4/6 inhibitors have reduced distant recurrence in the early stage setting and improved overall survival in the metastatic setting. Chemotherapy is used based on stage and tumor biology in the early stage setting and after endocrine resistance for advanced disease. New therapies, including novel endocrine agents and antibody-drug conjugates, are now changing the treatment landscape. With the availability of new treatment options, it is important to define the optimal sequence of treatment to maximize clinical benefit while minimizing toxicity. In this review, the authors first discuss the pathologic and molecular features of HR-positive/HER2-negative breast cancer and mechanisms of endocrine resistance. Then, they discuss current and emerging therapies for both early stage and metastatic HR-positive/HER2-negative breast cancer, including treatment algorithms based on current data.

Results of a Phase Ib Study Investigating Durvalumab in Combination with Eribulin in Patients with HER2-Negative Metastatic Breast Cancer and Recurrent Ovarian Cancer

INTRODUCTION

The release of tumor-associated antigens with cytotoxic chemotherapy treatment may enhance the response to immune checkpoint blockade. Eribulin is a microtubule inhibitor with proven overall survival (OS) benefit in metastatic breast cancer (MBC), which may also enhance intratumoral vascular remodeling. Durvalumab, a humanized monoclonal antibody, targets the programmed cell death ligand-1 (PD-L1) receptor. This study sought to determine the maximum tolerated dose and recommended phase II dose (RP2D) of eribulin in combination with durvalumab, as well as the safety and preliminary antitumor activity of the combination in patients with previously treated HER2-negative (HER2-) MBC and recurrent ovarian cancer (ROC).

METHODS

Cohorts of 3-6 patients with HER2- MBC and ROC were treated in a modified 3+3 design. Eligible patients received escalating doses of eribulin (1.1 mg/m2 or 1.4 mg/m2 IV on day 1 and day 8) with durvalumab (1.12 g IV on day 1) in 21-day cycles until dose-limiting toxicity (DLT), intolerable adverse events (AEs), disease progression, or other reasons for withdrawal.

PRIMARY ENDPOINT

the rate of DLTs during cycles 1 and 2 of therapy. Secondary endpoints: AE rate, objective response rate (ORR), progression-free survival (PFS), and OS.

RESULTS

Nine patients with a median of 4 prior therapies for advanced disease were treated: 5 patients with HER2- MBC (1 with triple-negative disease and 4 with hormone-positive disease) and 4 patients with ROC. The RP2D of eribulin was 1.4 mg/m2 in combination with durvalumab. There were no DLTs experienced during the first two cycles of therapy. The most common treatment-related AEs (>50%) were fatigue, neutropenia, decreased white blood cell count, anemia, AST and alkaline phosphatase elevation, hyperglycemia, and nausea; most were grade 1 or 2. There was one immune-related AE of grade 3 (hepatitis) after 5 cycles of treatment, for which patient came off study. Two other patients discontinued study drug related to toxicity (neutropenia [n = 1], hepatic toxicity [n = 1]). ORR was 55%, and 4 additional patients experienced stable disease. All MBC patients exhibited a response to therapy. Median PFS was 6.2 months. Median OS was 15.0 months.

CONCLUSION

The combination of eribulin at a dose of 1.4 mg/m2 with standard dose durvalumab had a favorable AE profile in patients with previously treated HER2- MBC and ROC. The early antitumor activity observed in all MBC patients enrolled in the study suggests that further investigation of this combination is warranted.

Evaluation of Time to Onset and Outcome of Lung Adverse Events Related to Pembrolizumab Using Marketing Surveillance

BACKGROUND

Pembrolizumab has been widely used in patients since its release, but detailed information on lung-specific adverse events (AEs) from post-marketing monitoring has not been reported.

OBJECTIVES

This study was undertaken to determine the risk of pembrolizumab-induced lung AEs, time to onset, and post hoc outcomes using the Japanese Adverse Drug Event Report database.

METHOD

We analyzed data for the period between April 2004 and March 2022. Data on lung AEs were extracted and the relative risks of AEs were estimated using reporting odds ratios.

RESULTS

We analyzed 2,021,907 reports and identified 15,306 reports of AEs caused by pembrolizumab, including 3,004 lung AEs. Signals were detected for 14 lung AEs. Interstitial lung disease was the most frequently reported (62.3%) and included fatal cases. A histogram of median time to onset showed occurrence ranging from 2 to 73 days, but some cases of interstitial lung disease occurred after 2 years of administration. The AEs showing the highest fatality rates were interstitial lung disease, respiratory failure, and pneumonia aspiration.

CONCLUSIONS

This study focused on lung AEs caused by pembrolizumab as post-marketing AEs. Some cases could potentially involve serious outcomes, so patients should be monitored for signs of AE onset not only at the start of administration but also over an extended period, especially for interstitial lung disease.

Concurrent predictors of an immune responsive tumor microenvironment within tumor mutational burden-high breast cancer

Background

Data supporting high tumor mutational burden (TMB-H) as a lone biomarker for an immune-responsive tumor microenvironment (TME) in metastatic breast cancer (MBC) are weak, yet tumor agnostic approval in TMB-H advanced tumors provides immune checkpoint inhibition (ICI) as a clinical option. We evaluated concurrent predictors of immune-responsive and non-responsive TME within MBC.

Methods

Tumor samples from patients with MBC (N=5621) were analyzed by next-generation sequencing of DNA (592-gene panel or whole exome) and RNA (whole transcriptome) at Caris Life Sciences (Phoenix, AZ). TMB-H threshold was set to ≥ 10 muts/Mb. PDL-1 was evaluated using SP142 antibody. Gene expression profiling and RNA deconvolution were used to estimate immune and stromal cell population abundance in the TME, and transcriptomic signature of immunotherapy response (T cell-inflamed score).

Results

461 (8.2%) TMB-H MBC samples were identified. Consistent with prior studies, TMB-H tumors exhibited significant dMMR/MSI-H enrichment (7 vs. 0%, p<0.0001) and PD-L1+ expression (36 vs. 28%, p<0.05) compared to TMB-L. Across all samples, T cell-inflamed scores were weakly correlated with TMB. TMB-H was not associated with significantly increased immune responsive cell types (CD8+ T-cells, NK cells, or B cells) or immune response gene signatures (e.g. antigen presentation), yet positive trends were observed, while immunosuppressive fibroblasts were significantly decreased in TMB-H tumors (0.84-fold change compared to TMB-L, P<0.05). HR+/HER2- breast cancer was the only subtype in which TMB-H tumors exhibited increased T cell-inflamed scores vs. TMB-L. Concurrent PD-L1+ or dMMR/MSI-H with TMB-H was associated with high T cell-inflamed scores in both HR+/HER2- and TNBC. Among several associated biomarkers, B2M mutations and CD274 amplifications were positively associated with T-cell inflamed scores in TMB-H tumors; CDH1 and ERBB2 mutations were negatively associated.

Conclusion

High TMB alone does not strongly correlate with immune infiltrate or immune-related gene signatures in MBC. TMB-H predicts T-cell inflamed signature compared to TMB-L in HR+/HER2- tumors only. Along with MSI-H and PD-L1+, several biomarkers, including B2M mutation and CD274 amplification, may help predict ICI benefit amongst TMB-H tumors. Co-occurring biomarkers within TMB-H breast cancer warrant evaluation in larger cohorts for response or resistance to ICI to develop composite predictive biomarkers in MBC.

Tumor Mutational Burden in Breast Cancer: Current Evidence, Challenges, and Opportunities

Tumor mutational burden (TMB) correlates with tumor neoantigen burden, T cell infiltration, and response to immune checkpoint inhibitors in many solid tumor types. Based on data from the phase II KEYNOTE-158 study, the anti-PD-1 antibody pembrolizumab was granted approval for treating patients with advanced solid tumors and TMB ≥ 10 mutations per megabase. However, this trial did not include any patients with metastatic breast cancer; thus, several questions remain unanswered about the true role of TMB as a predictive biomarker of benefit to immune checkpoint inhibitor therapy in breast cancer. In this review, we will discuss the challenges and opportunities in establishing TMB as a predictive biomarker of benefit to immunotherapy in metastatic breast cancer.

Advancements in clinical aspects of targeted therapy and immunotherapy in breast cancer

Breast cancer is the second leading cause of death for women worldwide. The heterogeneity of this disease presents a big challenge in its therapeutic management. However, recent advances in molecular biology and immunology enable to develop highly targeted therapies for many forms of breast cancer. The primary objective of targeted therapy is to inhibit a specific target/molecule that supports tumor progression. Ak strain transforming, cyclin-dependent kinases, poly (ADP-ribose) polymerase, and different growth factors have emerged as potential therapeutic targets for specific breast cancer subtypes. Many targeted drugs are currently undergoing clinical trials, and some have already received the FDA approval as monotherapy or in combination with other drugs for the treatment of different forms of breast cancer. However, the targeted drugs have yet to achieve therapeutic promise against triple-negative breast cancer (TNBC). In this aspect, immune therapy has come up as a promising therapeutic approach specifically for TNBC patients. Different immunotherapeutic modalities including immune-checkpoint blockade, vaccination, and adoptive cell transfer have been extensively studied in the clinical setting of breast cancer, especially in TNBC patients. The FDA has already approved some immune-checkpoint blockers in combination with chemotherapeutic drugs to treat TNBC and several trials are ongoing. This review provides an overview of clinical developments and recent advancements in targeted therapies and immunotherapies for breast cancer treatment. The successes, challenges, and prospects were critically discussed to portray their profound prospects.

A randomized trial of eribulin monotherapy versus eribulin plus anlotinib in patients with locally recurrent or metastatic breast cancer

BACKGROUND

Eribulin mesylate is a novel, nontaxane, microtubule dynamics inhibitor. In this study, we assessed the efficacy and safety of eribulin versus eribulin plus the oral small-molecule tyrosine kinase inhibitor anlotinib in patients with locally recurrent or metastatic breast cancer.

PATIENTS AND METHODS

In this single-center, open-label, phase II clinical study (NCT05206656) conducted in a Chinese hospital, patients with human epidermal growth factor receptor 2 (HER2)-negative, locally recurrent or metastatic breast cancer previously treated with anthracycline- or taxane-based chemotherapy were randomized (1 : 1) to receive eribulin alone or in combination with anlotinib. The primary efficacy endpoint was investigator-assessed progression-free survival (PFS).

RESULTS

From June 2020 to April 2022, a total of 80 patients were randomly assigned to either eribulin monotherapy or eribulin plus anlotinib combination therapy, with 40 patients in each group. The data cut-off was 10 August 2022. The median PFS was 3.5 months [95% confidence interval (CI) 2.8-5.5 months] for eribulin and 5.1 months (95% CI 4.5-6.9 months) for eribulin plus anlotinib (hazard ratio = 0.56, 95% CI 0.32-0.98; P = 0.04). The objective response rates were 32.5% versus 52.5% (P = 0.07), respectively, and disease control rates were 67.5% versus 92.5% (P = 0.01), respectively. Patients <50 years of age, with an Eastern Cooperative Oncology Group performance status score of 0, visceral metastasis, number of treatment lines of four or more, hormone receptor negative (triple-negative), and HER2 low expression appeared to benefit more from combined treatment. The most common adverse events in both groups were leukopenia (n = 28, 70.0%, patients in the eribulin monotherapy group versus n = 35, 87.5%, patients in the combination therapy group), aspartate aminotransferase elevations (n = 28, 70.0%, versus n = 35, 87.5%), neutropenia (n = 25, 62.5%, versus n = 31, 77.5%), and alanine aminotransferase elevations (n = 25, 62.5%, versus n = 30, 75.0%).

CONCLUSION

Eribulin plus anlotinib can be considered an alternative treatment option for HER2-negative locally advanced or metastatic breast cancer.

Eribulin mesylate exerts antitumor effects via CD103

Eribulin mesylate (ERB) is a synthetic analog of halichondrin B, inhibiting tumor cell growth by disrupting microtubule function. Recently, anticancer drugs have been shown to not only act directly on tumor cells but also to exert antitumor effects by modifying the tumor environment. Although ERB has also been speculated to modify the tumor microenvironment including the immune response to tumors, the precise mechanism remains unclear. In our study, ERB suppressed the tumor growth of MC38 colon cancer in wildtype mice, whereas ERB failed to inhibit the tumor growth in Rag1-deficient mice which lack both B and T cells. Moreover, depletion of either CD4+ or CD8+ T cells abrogated the antitumor effect of ERB, indicating that both CD4+ and CD8+ T cells play an important role in ERB-induced antitumor effects. Furthermore, ERB treatment increased the number of tumor infiltrating lymphocytes (TILs) as well as the expression of activation markers (CD38 and CD69), immune checkpoint molecules (LAG3, TIGIT and Tim3) and cytotoxic molecules (granzyme B and perforin) in TILs. ERB upregulated E-cadherin expression in MC38. CD103 is a ligand of E-cadherin and induces T-cell activation. ERB increased the proportion of CD103+ cells in both CD4+ and CD8+ TILs. The ERB-induced antitumor effect with the increased TIL number and the increased expression of activation markers, inhibitory checkpoint molecules and cytotoxic molecules in TILs was abrogated in CD103-deficient mice. Collectively, these results suggest that ERB exerts antitumor effects by upregulation of E-cadherin expression in tumor cells and subsequent activation of CD103+ TILs.

Tumor-Infiltrating Lymphocytes and PD-L1 Expression in Pleomorphic Lobular Breast Carcinoma

BACKGROUND

The prognostic and predictive role of stromal tumor-infiltrating lymphocytes (sTILs) is undetermined in pleomorphic invasive lobular cancer (pILC). The same applies for the expression of PD-1/PD-L1 in this rare breast cancer subtype. Here, we aimed to investigate the expression of sTILs and analyze the PD-L1 expression levels in pILC.

METHODS

Archival tissues from sixty-six patients with pILC were collected. The sTIL density was scored as a percentage of tumor area using the following cut-offs: 0%; <5%; 5-9%; and 10-50%. The PD-L1 expression was analyzed using IHC on formalin-fixed, paraffin-embedded tissue sections using SP142 and 22C3 antibodies.

RESULTS

A total of 82% of the sixty-six patients were hormone receptor positive and 8% of cases were triple negative (TN), while 10% showed human epidermal growth factor receptor 2 (HER2) amplification. sTILs (≥1%) were present in 64% of the study population. Using the SP142 antibody, 36% of tumors demonstrated a positive PD-L1 score of ≥1%, and using the 22C3 antibody, 28% had a positive PD-L1 score of ≥1. There was no correlation between sTILs or PD-L1 expression and tumor size, tumor grade, nodal status, expression of estrogen receptor (ER), or amplification of HER2. Our data did not show any difference in survival between the three molecular subtypes of pILC with respect to sTILs and PD-L1 expression.

CONCLUSION

This study shows that pILCs show some degree of sTILs and PD-L1 expression; however, this was not associated with a survival improvement. Additional large trials are needed to understand immune infiltration in lobular cancer, especially in the pleomorphic subtype.

Clinical Meaning of Stromal Tumor Infiltrating Lymphocytes (sTIL) in Early Luminal B Breast Cancer

Luminal breast cancer (BC) is associated with less immune activation, and the significance of stromal lymphocytic infiltration (sTIL) is more uncertain than in other BC subtypes. The aim of this study was to investigate the predictive and prognostic value of sTIL in early luminal BC. The study was performed with an observational design in a prospective cohort of 345 patients with predominantly high-risk luminal (hormone receptor positive, HER2 negative) BC and with luminal B features (n = 286), in which the presence of sTIL was analyzed with validated methods. Median sTIL infiltration was 5% (Q1-Q3 range (IQR), 0-10). We found that sTIL were associated with characteristics of higher biological and clinical aggressiveness (tumor and lymph node proliferation and stage, among others) and that the percentage of sTIL was predictive of pathologic complete response in patients treated with neoadjuvant chemotherapy (OR: 1.05, 95%CI 1.02-1.09, p < 0.001). The inclusion of sTIL (any level of lymphocytic infiltration: sTIL > 0%) in Cox regression multivariable prognostic models was associated with a shorter relapse-free interval (HR: 4.85, 95%CI 1.33-17.65, p = 0.016) and significantly improved its performance. The prognostic impact of sTIL was independent of other clinical and pathological variables and was mainly driven by its relevance in luminal B BC.

CCL19+ dendritic cells potentiate clinical benefit of anti-PD-(L)1 immunotherapy in triple-negative breast cancer

BACKGROUND

The extensive involvement of dendritic cells (DCs) in immune contexture indicates their potent value in cancer immunotherapy. Understanding DC diversity in patient cohorts may strengthen the clinical benefit of immune checkpoint inhibitors (ICIs).

METHODS

Single-cell profiling of breast tumors from two clinical trials was performed to investigate DC heterogeneity. Multiomics, tissue characterization, and pre-clinical experiments were used to evaluate the role of the identified DCs in the tumor microenvironment. Four independent clinical trials were leveraged to explore biomarkers to predict ICI and chemotherapy outcomes.

FINDINGS

We identified a distinct CCL19-expressing functional state of DCs associated with favorable responses to anti-programmed death (ligand)-1 (PD-(L)1), which displayed migratory and immunomodulatory phenotypes. These cells were correlated with antitumor T cell immunity and the presence of tertiary lymphoid structures and lymphoid aggregates, defining immunogenic microenvironments in triple-negative breast cancer. In vivo, CCL19⁺ DC deletion by Ccl19 gene ablation dampened CCR7⁺CD8⁺ T cells and tumor elimination in response to anti-PD-1. Notably, high circulating and intratumoral CCL19 levels were associated with superior response and survival in patients receiving anti-PD-1 but not chemotherapy.

CONCLUSIONS

We uncovered a critical role of DC subsets in immunotherapy, which has implications for designing novel therapies and patient stratification strategies.

FUNDING

This study was funded by the National Key Research and Development Project of China, the National Natural Science Foundation of China, the Program of Shanghai Academic/Technology Research Leader, the Natural Science Foundation of Shanghai, the Shanghai Key Laboratory of Breast Cancer, the Shanghai Hospital Development Center (SHDC), and the Shanghai Health Commission.

CircPVT1 promotes ER-positive breast tumorigenesis and drug resistance by targeting ESR1 and MAVS

The molecular mechanisms underlying estrogen receptor (ER)-positive breast carcinogenesis and endocrine therapy resistance remain incompletely understood. Here, we report that circPVT1, a circular RNA generated from the lncRNA PVT1, is highly expressed in ERα-positive breast cancer cell lines and tumor samples and is functionally important in promoting ERα-positive breast tumorigenesis and endocrine therapy resistance. CircPVT1 acts as a competing endogenous RNA (ceRNA) to sponge miR-181a-2-3p, promoting the expression of ESR1 and downstream ERα-target genes and breast cancer cell growth. Furthermore, circPVT1 directly interacts with MAVS protein to disrupt the RIGI-MAVS complex formation, inhibiting type I interferon (IFN) signaling pathway and anti-tumor immunity. Anti-sense oligonucleotide (ASO)-targeting circPVT1 inhibits ERα-positive breast cancer cell and tumor growth, re-sensitizing tamoxifen-resistant ERα-positive breast cancer cells to tamoxifen treatment. Taken together, our data demonstrated that circPVT1 can work through both ceRNA and protein scaffolding mechanisms to promote cancer. Thus, circPVT1 may serve as a diagnostic biomarker and therapeutic target for ERα-positive breast cancer in the clinic.

New Developments in Systemic Management for High-Risk Early-Stage Hormone-Receptor-Positive, HER2-Negative Breast Cancer

OPINION STATEMENT

For high-risk early-stage hormone-receptor-positive, HER2-negative breast cancer (HR + /HER2 - EBC), short- and long-term recurrence risks remain substantial despite local control with surgery and radiation and systemic treatment with chemotherapy and endocrine therapy (ET). Recent trials have provided new strategies for reducing recurrence. The monarchE trial demonstrated that adding 2 years of adjuvant abemaciclib to ET improves invasive disease-free survival (iDFS) and distant recurrence-free survival (DRFS). In the OlympiA trial for high-risk disease in patients with germline BRCA1/BRCA2 mutations, adding 1 year of olaparib to ET improved iDFS, DRFS, and overall survival (OS). In addition, for premenopausal women with high-risk tumors, long-term follow-up of the SOFT, ASTRRA, TEXT, ABCSG-12, and HOBOE trials supports the role of ovarian function suppression (OFS), in combination with adjuvant tamoxifen or aromatase inhibition (AI). For postmenopausal women with high-risk tumors, extended-duration AI for at least 7 years should be used with zoledronic acid. Given the remaining recurrence risk even with these interventions and with the ongoing development of new strategies for HR + disease, patients with high-risk EBC should be encouraged to participate in clinical trials, such as trials of immunotherapy, novel oral estrogen receptor alpha (ERα)-targeting agents, antibody-drug conjugates (ADCs), and trials guided by measurements of minimal residual disease (MRD).

Immunotherapy Approaches for Breast Cancer Patients in 2023

Immunotherapy, particularly agents targeting the immunoregulatory PD-1/PD-L1 axis, harnesses the power of the immune system to treat cancer, with unique potential for a durable treatment effect due to immunologic memory. The PD-1 inhibitor pembrolizumab combined with neoadjuvant chemotherapy followed by adjuvant pembrolizumab improves event-free survival and is a new standard of care for high-risk, early-stage triple-negative breast cancer (TNBC), regardless of tumor PD-L1 expression. For metastatic TNBC, pembrolizumab combined with chemotherapy is a new standard of care for the first-line therapy of PD-L1⁺ metastatic TNBC, with improvement in overall survival. The PD-L1 inhibitor atezolizumab combined with nab-paclitaxel is also approved outside the United States for the first-line treatment of metastatic PD-L1⁺ TNBC. Current research focuses on refining the use of immunotherapy in TNBC by defining informative predictive biomarkers, developing immunotherapy in early and advanced HER2-driven and luminal breast cancers, and overcoming primary and secondary resistance to immunotherapy through unique immune-based strategies.

PD-L1 blockade in combination with carboplatin as immune induction in metastatic lobular breast cancer: the GELATO trial

Invasive lobular breast cancer (ILC) is the second most common histological breast cancer subtype, but ILC-specific trials are lacking. Translational research revealed an immune-related ILC subset, and in mouse ILC models, synergy between immune checkpoint blockade and platinum was observed. In the phase II GELATO trial ( NCT03147040 ), patients with metastatic ILC were treated with weekly carboplatin (area under the curve 1.5 mg ml-1 min-1) as immune induction for 12 weeks and atezolizumab (PD-L1 blockade; triweekly) from the third week until progression. Four of 23 evaluable patients had a partial response (17%), and 2 had stable disease, resulting in a clinical benefit rate of 26%. From these six patients, four had triple-negative ILC (TN-ILC). We observed higher CD8+ T cell infiltration, immune checkpoint expression and exhausted T cells after treatment. With this GELATO trial, we show that ILC-specific clinical trials are feasible and demonstrate promising antitumor activity of atezolizumab with carboplatin, particularly for TN-ILC, and provide insights for the design of highly needed ILC-specific trials.

Metastasis of breast cancer to bones alters the tumor immune microenvironment

BACKGROUND

Bone is one of the most frequent sites for breast cancer metastasis. Breast cancer bone metastasis (BCBM) leads to skeletal morbidities including pain, fractures, and spinal compression, all of which severely impact quality of life. Immunotherapy is a promising therapy for patients with advanced cancer, but whether it may provide benefit to metastatic bone cancer is currently unknown. Thus, a better understanding of the immune landscape of bone-disseminated breast cancers may reveal new therapeutic strategies. In this study, we use histopathological analysis to investigate changes within the immune microenvironment of primary breast cancer and paired BCBM.

METHODS

Sixty-three patients with BCBM, including 31 with paired primary and bone metastatic lesions, were included in our study. The percentage of stroma and stromal tumor-infiltrating lymphocytes (TILs) was evaluated by histopathological analysis. The quantification of stromal TILs (CD4 + and CD8 +), macrophages (CD68 + and HLA-DR +), programmed cell death protein 1 (PD-1), and programmed cell death protein ligand 1 (PD-L1) was evaluated through immunohistochemical (IHC) staining. Statistical analysis was performed with paired t test, Wilcoxon test, spearman correlation test, and univariate and multivariate cox regression.

RESULTS

Median survival after BCBM pathological diagnosis was 20.5 months (range: 3-95 months). Of the immune parameters measured, none correlated with survival after bone metastasis was diagnosed. Compared to the primary site, bone metastases exhibited more tumor stroma (mean: 58.5% vs 28.87%, p < 0.001) and less TILs (mean: 8.45% vs 14.03%, p = 0.042), as determined by H&E analysis. The quantification of primary vs metastatic tissue area with CD4 + (23.95/mm² vs 51.69/mm², p = 0.027 and with CD8 + (18.15/mm² vs 58.95/mm², p = 0.004) TILs similarly followed this trend and was reduced in number for bone metastases. The number of CD68 + and HLA-DR + macrophages showed no significant difference between primary sites and bone metastases. PD-1 expression was present in 68.25% of the bone metastasis, while PD-L1 expression was only present in 7.94% of the bone metastasis.

CONCLUSIONS

Our findings suggest that compared to the primary breast cancer site, bone metastases harbor a less active immune microenvironment. Despite this relatively dampened immune landscape, expression of PD-1 and PD-L1 in the bone metastasis indicates a potential benefit from immune checkpoint inhibitors for some BCBM cases.

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.

Immune-based combination therapy to convert immunologically cold tumors into hot tumors: an update and new insights

As a breakthrough strategy for cancer treatment, immunotherapy mainly consists of immune checkpoint inhibitors (ICIs) and other immunomodulatory drugs that provide a durable protective antitumor response by stimulating the immune system to fight cancer. However, due to the low response rate and unique toxicity profiles of immunotherapy, the strategies of combining immunotherapy with other therapies have attracted enormous attention. These combinations are designed to exert potent antitumor effects by regulating different processes in the cancer-immunity cycle. To date, immune-based combination therapy has achieved encouraging results in numerous clinical trials and has received Food and Drug Administration (FDA) approval for certain cancers with more studies underway. This review summarizes the emerging strategies of immune-based combination therapy, including combinations with another immunotherapeutic strategy, radiotherapy, chemotherapy, anti-angiogenic therapy, targeted therapy, bacterial therapy, and stroma-targeted therapy. Here, we highlight the rationale of immune-based combination therapy, the biomarkers and the clinical progress for these immune-based combination therapies.

Evolving treatment landscape of immunotherapy in breast cancer: current issues and future perspectives

Immune checkpoint inhibitors (ICIs) deeply changed the treatment landscape of breast cancer (BC). In particular, anti-programmed-death (ligand) 1 antibodies were approved for the treatment of triple-negative breast cancer (TNBC), both in first line for metastatic disease and in neoadjuvant setting, on the basis of a demonstrated improvement of the survival outcomes. In light of these results, current clinical trials aim at improving this benefit investigating novel combinations and strategies, at exploring the role of ICIs beyond TNBC, and at better selecting the patients in order to spare non-responders from avoidable toxicities. This narrative review aims at summarizing and discussing the evolving landscape of immunotherapeutic treatments for BC, highlighting the current challenges and the future perspectives.

Complete remissions following immunotherapy or immuno-oncology combinations in cancer patients: the MOUSEION-03 meta-analysis

BACKGROUND

Immunotherapy has determined unprecedented long-term responses in several hematological and solid tumors. In the MOUSEION-03 study, we conducted a meta-analysis to determine the possibility of achieving complete remissions (CR) with immunotherapy or immuno-oncology combinations in cancer patients.

METHODS

The primary endpoint was to assess the incidence of CR in cancer patients receiving immune checkpoint inhibitors (ICIs) alone or in combination with other agents versus control treatments. The pooled odds ratio (OR) and 95% confidence interval (CI) for CR rate were extracted.

RESULTS

A total of 12,130 potentially relevant trials were identified; 5 phase II and 80 phase III randomized studies (37 monotherapies and 48 combinations) and 49,425 cancer patients were included. The most frequent types of malignancies were non-small cell lung cancer (n = 14,249; 29%), urothelial cancer (n = 6536; 13%), renal cell carcinoma (n = 5743; 12%), and melanoma (n = 2904; 6%). In patients treated with immunotherapy (as monotherapy or in combination with other anticancer agents), the pooled OR was 1.67 (1.52-1.84). The highest OR was registered by immune-based combinations with two ICIs (3.56, 95% CI 1.28-9.90).

CONCLUSIONS

To the best of the authors' knowledge, no comprehensive meta-analysis on the use of ICIs and ICI-based combinations in solid tumors to systematically investigate the probability to achieve CR has been published so far. Although CR is not a common event in several cancer patients receiving immunotherapy, the MOUSEION-03 suggests that the use of ICIs may significantly increase the chance of achieving CR in comparison with control treatments.

Identification of prognostic cancer-associated fibroblast markers in luminal breast cancer using weighted gene co-expression network analysis

Background

Cancer-associated fibroblasts (CAFs) play a pivotal role in cancer progression and are known to mediate endocrine and chemotherapy resistance through paracrine signaling. Additionally, they directly influence the expression and growth dependence of ER in Luminal breast cancer (LBC). This study aims to investigate stromal CAF-related factors and develop a CAF-related classifier to predict the prognosis and therapeutic outcomes in LBC.

Methods

The Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO) databases were utilized to obtain mRNA expression and clinical information from 694 and 101 LBC samples, respectively. CAF infiltrations were determined by estimating the proportion of immune and cancer cells (EPIC) method, while stromal scores were calculated using the Estimation of STromal and Immune cells in MAlignant Tumors using Expression data (ESTIMATE) algorithm. Weighted gene co-expression network analysis (WGCNA) was used to identify stromal CAF-related genes. A CAF risk signature was developed through univariate and least absolute shrinkage and selection operator method (LASSO) Cox regression model. The Spearman test was used to evaluate the correlation between CAF risk score, CAF markers, and CAF infiltrations estimated through EPIC, xCell, microenvironment cell populations-counter (MCP-counter), and Tumor Immune Dysfunction and Exclusion (TIDE) algorithms. The TIDE algorithm was further utilized to assess the response to immunotherapy. Additionally, Gene set enrichment analysis (GSEA) was applied to elucidate the molecular mechanisms underlying the findings.

Results

We constructed a 5-gene prognostic model consisting of RIN2, THBS1, IL1R1, RAB31, and COL11A1 for CAF. Using the median CAF risk score as the cutoff, we classified LBC patients into high- and low-CAF-risk groups and found that those in the high-risk group had a significantly worse prognosis. Spearman correlation analyses demonstrated a strong positive correlation between the CAF risk score and stromal and CAF infiltrations, with the five model genes showing positive correlations with CAF markers. In addition, the TIDE analysis revealed that high-CAF-risk patients were less likely to respond to immunotherapy. Gene set enrichment analysis (GSEA) identified significant enrichment of ECM receptor interaction, regulation of actin cytoskeleton, epithelial-mesenchymal transition (EMT), and TGF-β signaling pathway gene sets in the high-CAF-risk group patients.

Conclusion

The five-gene prognostic CAF signature presented in this study was not only reliable for predicting prognosis in LBC patients, but it was also effective in estimating clinical immunotherapy response. These findings have significant clinical implications, as the signature may guide tailored anti-CAF therapy in combination with immunotherapy for LBC patients.

Immune Checkpoint Inhibitors and Novel Immunotherapy Approaches for Breast Cancer

PURPOSE OF REVIEW

To critically review the existing evidence on immune checkpoint inhibitors (ICIs) in early-stage and metastatic breast cancer and discuss emerging strategies in the different breast cancer subtypes.

RECENT FINDINGS

Immunotherapy has become one of the major milestones in contemporary oncology, revolutionizing the treatment of multiple solid tumors. ICI agents combined with chemotherapy have demonstrated significant efficacy in both early-stage and metastatic triple-negative breast cancer. However, only a subgroup of patients responds to those agents and some associated toxicities, although infrequent, can be life-disabling. Emerging data from immunotherapy studies in advanced hormone receptor-positive (HR +) breast cancer as well as HER2-positive disease are arising with mixed results. Although breast cancer has not classically been considered a hot tumor, ICIs have proven to be effective in a subset of breast cancer patients. However, much remains to be learned, and the identification of new biomarkers beyond PD-L1 expression is essential not only to improve the efficacy of ICI but also to identify patients who can avoid them, together with their toxicities and costs.

Updates in combined approaches of radiotherapy and immune checkpoint inhibitors for the treatment of breast cancer

Breast cancer is the most prevalent non-skin cancer diagnosed in females and developing novel therapeutic strategies to improve patient outcomes is crucial. The immune system plays an integral role in the body’s response to breast cancer and modulating this immune response through immunotherapy is a promising therapeutic option. Although immune checkpoint inhibitors were recently approved for the treatment of breast cancer patients, not all patients respond to immune checkpoint inhibitors as a monotherapy, highlighting the need to better understand the biology underlying patient response. Additionally, as radiotherapy is a critical component of breast cancer treatment, understanding the interplay of radiation and immune checkpoint inhibitors will be vital as recent studies suggest that combined therapies may induce synergistic effects in preclinical models of breast cancer. This review will discuss the mechanisms supporting combined approaches with radiotherapy and immune checkpoint inhibitors for the treatment of breast cancer. Moreover, this review will analyze the current clinical trials examining combined approaches of radiotherapy, immunotherapy, chemotherapy, and targeted therapy. Finally, this review will evaluate data regarding treatment tolerance and potential biomarkers for these emerging therapies aimed at improving breast cancer outcomes.

Multiplexed In Situ Spatial Protein Profiling in the Pursuit of Precision Immuno-Oncology for Patients with Breast Cancer

Immune checkpoint inhibitors (ICIs) have revolutionized the treatment of many solid tumors. In breast cancer (BC), immunotherapy is currently approved in combination with chemotherapy, albeit only in triple-negative breast cancer. Unfortunately, most patients only derive limited benefit from ICIs, progressing either upfront or after an initial response. Therapeutics must engage with a heterogeneous network of complex stromal-cancer interactions that can fail at imposing cancer immune control in multiple domains, such as in the genomic, epigenomic, transcriptomic, proteomic, and metabolomic domains. To overcome these types of heterogeneous resistance phenotypes, several combinatorial strategies are underway. Still, they can be predicted to be effective only in the subgroups of patients in which those specific resistance mechanisms are effectively in place. As single biomarker predictive performances are necessarily suboptimal at capturing the complexity of this articulate network, precision immune-oncology calls for multi-omics tumor microenvironment profiling in order to identify unique predictive patterns and to proactively tailor combinatorial treatments. Multiplexed single-cell spatially resolved tissue analysis, through precise epitope colocalization, allows one to infer cellular functional states in view of their spatial organization. In this review, we discuss-through the lens of the cancer-immunity cycle-selected, established, and emerging markers that may be evaluated in multiplexed spatial protein panels to help identify prognostic and predictive patterns in BC.

Immunotherapy and breast cancer: an overview

PURPOSE OF REVIEW

Recently, immune checkpoint inhibitors (ICI) have demonstrated survival benefits in triple-negative breast cancer (TNBC) patients, treated in both the advanced and the early settings.

RECENT FINDINGS

As monotherapy, ICI failed to demonstrate a superiority over chemotherapy in pretreated advanced TNBC. In the first-line setting, ICI in combination with chemotherapy have shown consistent gains in progression-free survival in programmed death-ligand 1-positive TNBC, but only pembrolizumab indisputably demonstrated a significant overall survival benefit. In early-stage TNBC patients treated with neoadjuvant chemotherapy (NAC), ICI may improve the pathological complete response (pCR) rate. In the KEYNOTE-522 trial enrolling stage II to III TNBC patients, pembrolizumab, in combination with a NAC composed of carboplatin-paclitaxel followed by anthracyclines, and continued in the adjuvant phase led to significant increases in both pCR and disease-free survival, a practice-changing result in the field. Importantly, no unexpected safety signal was observed, but the possibility of definitive ICI-related toxicities may be challenging in curable early disease.

SUMMARY

Immunotherapy is now an important component in the therapeutic management of TNBC. Unresolved issues include the best chemotherapy partners, additional biomarkers to maximize the clinical benefit, and the possible extension of its use to other breast cancer subtypes.

Investigating the Role of CTCs with Stem/EMT-like Features in Metastatic Breast Cancer Patients Treated with Eribulin Mesylate

Simple Summary

Eribulin mesylate, an anti-mitotic drug used for the treatment of metastatic breast cancer (BC), exhibits significant effects on cancer cell migration, invasion, and metastatic seeding in experimental models. Interestingly, eribulin treatment has been shown to target the cancer stem cell (CSC) subsets in vitro and reverse the epithelial-to-mesenchymal transition (EMT) state of BC cells. In the current study, circulating tumor cells (CTCs) identified in the peripheral blood of patients with metastatic BC were analyzed at different time points during eribulin treatment and on disease progression. The results contribute new data on the mechanisms of resistance to eribulin mesylate and the prognostic relevance of CTC analyses for eribulin-treated metastatic BC.

Abstract

We herein aimed to assess the effect of eribulin mesylate on the cancer stem cell (CSC)/EMT-like phenotype of CTCs, and to investigate the prognostic role of CTC detection and monitoring for eribulin-treated BC patients. Peripheral blood was obtained at baseline (n = 42 patients) and 8 days after treatment initiation (C1D8: n = 22), and on disease progression (PD: n = 26). PBMCs cytospins were immunofluorescently stained for Cytokeratins/ALDH1/TWIST1/DAPI and analyzed via Ariol microscopy. CTCs were detected in 33.3%, 27.3%, and 23.1% of patients at baseline, C1D8, and PD, respectively. Accordingly, partial-EMT+ CTCs represented 61.3%, 0%, and 37.5% of total CTCs, whereas the CSC-like phenotype was consistently expressed by 87.5%, 75%, and 91.7% of CTCs at the respective time points. Interestingly, the CSC+/partial-EMT+ subset prevailed at baseline, but it was eradicated on C1D8 and resurged again during PD. CTC detection at baseline was associated with reduced PFS (p = 0.007) and OS (p = 0.005), and was an independent risk factor for death (HR: 3.779, p = 0.001; multivariate analysis). The CSC+/partial-EMT+ CTCs emerged as the only subset with adverse prognostic significance, while CTC monitoring during eribulin therapy improved the prediction of disease progression. These results indicate that resistant CTC subsets persevere eribulin treatment and highlight the prognostic implications of CTC analyses for eribulin-treated BC patients.

Tumor infiltrating lymphocytes (TILs) as a predictive biomarker of response to checkpoint blockers in solid tumors: a systematic review

Immunotherapy is a standard of care in many solid tumors but many patients derive limited benefit from it. There is increasing interest toward tumor infiltrating lymphocytes (TILs) since their presence may be related with good outcomes from treatment with immune checkpoint blockers. We aimed at systematically reviewing existing evidence about the role of TILs as possible predictors of response to immunotherapy in solid tumors. We reviewed 1193 records published from January 2010 until December 2021. Associations between TILs and outcomes were observed mainly in melanoma and breast cancer. Overall survival and overall response rate for advanced disease and pathological complete response for early-phase tumors were the most commonly assessed endpoints. No definitive conclusion can be drawn on the predictive role of TILs. Additional studies, exploiting data from prospective, randomized clinical trials should further evaluate TILs also with the aim of identifying standard cut-off to differentiate between high and low TILs.

Combinatorial Strategies With PD-1/PD-L1 Immune Checkpoint Blockade for Breast Cancer Therapy: Mechanisms and Clinical Outcomes

As an emerging antitumor strategy, immune checkpoint therapy is one of the most promising anticancer therapies due to its long response duration. Antibodies against the programmed death-1 (PD-1) and programmed death ligand-1 (PD-L1) axis have been extensively applied to various cancers and have demonstrated unprecedented efficacy. Nevertheless, a poor response to monotherapy with anti-PD-1/PD-L1 has been observed in metastatic breast cancer. Combination therapy with other standard treatments is expected to overcome this limitation of PD-1/PD-L1 blockade in the treatment of breast cancer. In the present review, we first illustrate the biological functions of PD-1/PD-L1 and their role in maintaining immune homeostasis as well as protecting against immune-mediated tissue damage in a variety of microenvironments. Several combination therapy strategies for the combination of PD-1/PD-L1 blockade with standard treatment modalities have been proposed to solve the limitations of anti-PD-1/PD-L1 treatment, including chemotherapy, radiotherapy, targeted therapy, antiangiogenic therapy, and other immunotherapies. The corresponding clinical trials provide valuable estimates of treatment effects. Notably, several combination options significantly improve the response and efficacy of PD-1/PD-L1 blockade. This review provides a PD-1/PD-L1 clinical trial landscape survey in breast cancer to guide the development of more effective and less toxic combination therapies.

Immune Checkpoint Blockade in Hormone Receptor-Positive Breast Cancer: Resistance Mechanisms and Future Perspectives

Anti-programmed cell death protein 1 immunotherapy has been incorporated in the treatment algorithm of triple-negative breast cancer (TNBC). However, clinical trial results for patients with hormone receptor (HR)-positive disease appear less compelling. HR-positive tumors exhibit lower levels of programmed death-ligand 1 expression in comparison with their triple-negative counterparts. Moreover, signaling through estrogen receptor alters the immune microenvironment, rendering such tumors immunologically "cold." To explain differential responses to immune checkpoint blockade, this review interrogates differences between HR-positive and TNBC. Starting from distinct genomic features, we further present disparities concerning the tumor microenvironment and finally, we summarize early-phase clinical trial results on promising novel immunotherapy combinations.

Targeted Therapeutic Options and Future Perspectives for HER2-Positive Breast Cancer

Simple Summary

The development of several antiHuman Epidermal Growth Factor Receptor 2 (HER2) treatments over the last few years has improved the landscape of HER2-positive breast cancer. Despite this, relapse is still the main issue in HER2-positive breast cancer. The reasons for therapeutic failure lie in the heterogeneity of the disease itself, as well as in the drug resistance mechanisms. In this review, we intended to understand the milestones that have had an impact on this disease up to their implementation in clinical practice. In addition, understanding the underlying molecular biology of HER2-positive disease is essential for the optimization and personalization of the different treatment options. For this reason, we focused on two relevant aspects, which are triple-positive disease and the role that modulation of the immune response might play in treatment and prognosis.

Abstract

Despite the improvement achieved by the introduction of HER2-targeted therapy, up to 25% of early human epidermal growth factor receptor 2-positive (HER2+) breast cancer (BC) patients will relapse. Beyond trastuzumab, other agents approved for early HER2+ BC include the monoclonal antibody pertuzumab, the antibody-drug conjugate (ADC) trastuzumab-emtansine (T-DM1) and the reversible HER2 inhibitor lapatinib. New agents, such as trastuzumab-deruxtecan or tucatinib in combination with capecitabine and trastuzumab, have also shown a significant improvement in the metastatic setting. Other therapeutic strategies to overcome treatment resistance have been explored in HER2+ BC, mainly in HER2+ that also overexpress estrogen receptors (ER+). In ER+ HER2+ patients, target therapies such as phosphoinositide-3-kinase (PI3K) pathway inhibition or cyclin-dependent kinases 4/6 blocking may be effective in controlling downstream of HER2 and many of the cellular pathways associated with resistance to HER2-targeted therapies. Multiple trials have explored these strategies with some promising results, and probably, in the next years conclusive results will succeed. In addition, HER2+ BC is known to be more immunogenic than other BC subgroups, with high variability between tumors. Different immunotherapeutic agents such as HER-2 therapy plus checkpoint inhibitors, or new vaccines approaches have been investigated in this setting, with promising but controversial results obtained to date.