Advanced Triple-negative Breast Cancer Research Articles

SDF-1 expression and tumor-infiltrating lymphocytes identify clinical subtypes of triple-negative breast cancer with different responses to neoadjuvant chemotherapy and survival.

In this study, we investigated the prediction and prognostic value of SDF-1 for triple-negative breast cancer (TNBC) patients who underwent neoadjuvant chemotherapy (NAC) following standard radical surgery. A total of 303 TNBC patients were included in this study. The NAC regimen was weekly paclitaxel plus carboplatin (PC) for all patients. SDF-1 and CXCR4 expression were measured at baseline and surgery via enzyme-linked immunosorbent assay (ELISA) and immunohistochemistry (IHC), respectively. Correlations between variables and treatment response were studied, and Cox proportional hazards regression analysis was implemented for prognostic evaluation. Of the 303 patients, 103 (34.0%) experienced pathological complete response (pCR) after completion of NAC. Serum SDF-1 expression before NAC was significantly correlated with the abundance of TILs. A higher pCR rate was more likely to be observed in patients with lower serum SDF-1 levels before NAC (P=0.001, OR=0.997, 95% CI: 0.996-0.999) and higher levels of TILs (P=0.005). In the multivariate survival model for nonpCR patients, serum SDF-1 expression at surgery served as an independent prognostic value for survival (high level, HR=1.980, 95% CI: 1.170-3.350, low level was used as a reference; P=0.011). Additionally, the predictive and prognostic value of serum SDF-1 expression was significant in patients with high abundance of TILs but not in patients with low abundance of TILs. This study contributes to the clarification of the value of serum SDF-1 to predict pCR and survival for TNBC patients who underwent NAC. This new serum marker, together with TILs, might help identify clinical subtypes of TNBC with different treatment responses and survival and play an important role in tailoring and modifying the NAC strategy for advanced TNBCs in the future.

Metronomic Chemotherapy is an Effective and Well Tolerated Treatment in Advanced Triple Negative Breast Cancer Patients: A Case Report of a Very Long Responder and Literature Review

Metronomic Chemotherapy is an Effective and Well Tolerated Treatment in Advanced Triple Negative Breast Cancer Patients: A Case Report of a Very Long Responder and Literature Review

Role of High-Dose Adjuvant Chemotherapy Followed by Autologous Stem Cell Transplantation in Locally Advanced Triple-Negative Breast Cancer: A Retrospective Chart Review.

Purpose Women with locally advanced/high-risk triple-negative breast cancer treated with the current standard chemotherapy continue to have a poor prognosis. High-dose chemotherapy with autologous stem cell transplant as treatment for locally advanced/high-risk breast cancer remains controversial due to a lack of survival benefit seen in previous phase III trials. However, these trials evaluated a heterogeneous group of patients with different receptor subtypes. A marginal benefit was observed in certain subgroups. We report long-term outcomes of women with stage IIB or III triple-negative breast cancer treated with high-dose chemotherapy followed by autologous stem cell transplant at our institution between 1995 and 2001. Methods This is a retrospective analysis of stage IIB or stage III triple-negative breast cancer treated with high-dose chemotherapy followed by autologous stem cell transplant. We excluded women with hormone-positive, HER2/neu-positive/unknown, and/or metastatic disease prior to transplant as per updated AJCC 7th edition guidelines. Patients underwent surgery and either neoadjuvant or adjuvant anthracycline and taxane-based chemotherapy and then proceeded to high-dose chemotherapy and autologous stem cell transplant using carmustine 600 mg/sqm, cyclophosphamide 5.6gm/sqm, and cisplatin 165 mg/sqm (STAMP 1 regimen) for consolidation. This was followed by locoregional breast and lymph node radiation per standard of care. Results Twenty-nine women (2 stage IIB and 27 stage III) were evaluated. The median age at diagnosis was 43 years (IQR: 40, 51). Eleven patients had 4–9 regional lymph nodes (LN) involved and 16 had 10+ involved LNs. Four patients had T4 or inflammatory breast cancer and two had ipsilateral supraclavicular LNs involved. The median follow-up time is 16 years (95% CI: 12, 19, range <1–19 y) posttransplant. The median overall survival was 15 years (95% CI: 3, 19); the median DFS was 14 years (95% CI: 1, 19). Conclusions This study of locally advanced/high-risk triple-negative breast cancer treated with adjuvant high-dose chemotherapy and autologous stem cell transplant reveals high overall survival rate. With the current improvement in treatment-related mortality, re-evaluating this approach in this subset of high-risk breast cancer in prospective randomized studies may be worthwhile.

The speckle-type POZ protein (SPOP) inhibits breast cancer malignancy by destabilizing TWIST1

Epithelial-mesenchymal transition (EMT) inducing transcription factor TWIST1 plays a vital role in cancer metastasis. How the tumor-suppressive E3 ligase, speckle-type POZ protein (SPOP), regulates TWIST1 in breast cancer remains unknown. In this study, we report that SPOP physically interacts with, ubiquitinates, and destabilizes TWIST1. SPOP promotes K63-and K48-linked ubiquitination of TWIST1, predominantly at K73, thereby suppressing cancer cell migration and invasion. Silencing SPOP significantly enhances EMT, which accelerates breast cancer cell migration and invasiveness in vitro and lung metastasis in vivo. Clinically, SPOP is negatively correlated with the levels of TWIST1 in highly invasive breast carcinomas. Reduced SPOP expression, along with elevated TWIST1 levels, is associated with poor prognosis in advanced breast cancer patients, particularly those with metastatic triple-negative breast cancer (TNBC). Taken together, we have disclosed a new mechanism linking SPOP to TWIST1 degradation. Thus SPOP may serve as a prognostic marker and a potential therapeutic target for advanced TNBC patients.

STAT3 and PD-L1 are negatively correlated with ATM and have impact on the prognosis of triple-negative breast cancer patients with low ATM expression.

Triple-negative breast cancer (TNBC) is known for its aggressive behaviors and lacking of effective treatment. Programmed cell death ligand-1 (PD-L1) inhibitor has just been approved for using in the management of advanced TNBC. To accurately screen TNBC sensitive to anti-PD-L1 treatment and to explore the feasibility of the ataxia-telangiectasia mutation protein (ATM) inhibitor combined with PD-L1 inhibitor, radiotherapy and chemotherapy, we focus on whether ATM participates in the regulation of PD-L1 and affects the prognosis of patients through c-Src, signal transducer and activator of transcription 1&3 (STAT1 and STAT3). We used immunohistochemical staining to explore the relationship of ATM with c-Src, STAT1, STAT3, PD-1/PD-L1, Tumor-infiltrating lymphocytes (TILs), as well as other clinicopathologic features in 86 pathological stage III TNBCs. Their impact on prognosis was also explored. We found ATM expression was negatively correlated with STAT1, STAT3, PD-L1, TILs and CD8 + cells in TNBC. STAT1 positively correlated the expression of PD-L1. In TNBC with ATM low expression, STAT3 was an independent factor for improved prognosis, while PD-L1 was an independent negative prognostic factor. Furthermore, in low ATM group, the phosphorylation of tyrosine at position 419 of c-Src (p-c-src Y419) was correlated with the overexpression of STAT3. Locally advanced TNBC with low ATM expression may be more likely to benefit from anti-PD-L1 inhibitors. The feasibility of ATM functional inhibitor combined with immune checkpoint blockade therapies in the treatment of TNBC is also worthy of further exploration. Our study suggests that STAT3 has different impacts on tumor progression in different tumors.

213MO Primary endpoint analysis of a randomized phase II of darolutamide or capecitabine in patients with triple-negative androgen receptor-positive advanced breast cancer (UCBG3-06 START trial)

A subgroup of triple negative breast cancer (TNBC) expresses the androgen receptor (AR). In this trial we evaluated the efficacy and tolerability of the AR inhibitor darolutamide (D) or capecitabine (C) in patients (pts) with advanced AR-positive TNBC (NCT03383679). Pts with centrally reviewed AR-positive (≥ 10% by immunohistochemistry) TNBC treated with up to one line of chemotherapy for advanced disease were eligible. They were randomized in a 2:1 ratio to receive D 600 mg twice daily or C 1000 mg/m2 twice daily 2-weeks on/ 1-week off, until progression or unacceptable toxicity. Primary endpoint was clinical benefit rate (CBR) at 16 weeks and was assessed in the eligible population and in the sensitivity analysis population (pts with delayed tumour assessment performed in the context of COVID pandemic). Main secondary endpoints included objective response rate, overall survival, progression-free survival (PFS) and safety. A total of 254 pts from 45 centres were screened; 94 pts were randomized (61 in D arm, 33 in C arm) from April 2018 to July 2021. A clinical benefit was observed in D arm in 13 of 53 evaluable pts (CBR at 16 weeks 24.5%; 95% CI: 12.9%-36.1%) including 2 PR and 1 CR and in C arm in 11 of 23 evaluable pts (CBR at 16 weeks 47.8%; 95% CI: 27.4%-68.2%). In the sensitivity analysis, a clinical benefit was observed in D arm in 17 of 58 evaluable patients (CBR ≥ 16 weeks 29.3%; 95% CI: 17.6%-41.0%) and in C arm in 19 of 32 evaluable patients (CBR ≥ 16 weeks 59.4%; 95% CI: 42.3%-76.4%). 7 pts presented with drug-related serious adverse events: 3 in D arm and 4 in C arm. In D arm, asthenia (26.7%), nausea (25%) and ASAT increase (21.7%) were the most common adverse events, the majority being grade 1 or 2, similar to previous safety data. Median PFS were 1.8 months (CI 95% 1.7-3.1) and 3.6 months (1.8-9.1) in D arm and C arm respectively. Other secondary endpoints will be presented at the meeting. Despite not reaching the pre-specified CBR, darulotamide demonstrated clinical activity with significant benefit for a group of patients. A research program to identify predictive biomarkers of sensitivity is ongoing.

Efficacy and safety of taxanes combined with chemotherapy drugs in advanced triple negative breast cancer: A meta-analysis of 26 randomized controlled trials.

BackgroundResearchers have demonstrated that the combined use of taxanes and chemotherapy drugs, especially paclitaxel-based treatment, appeared to clinically benefit on advanced triple negative breast cancer (TNBC). This meta-analysis aims to obtain the existent evidence on efficacy and safety for taxanes-based combination therapy to treat advanced TNBC.MethodsFrom 1991 to June 2022, seven databases (PubMed, Web of Science, Cochrane Library, Embase VIP, Wanfang, and CNKI databases) were comprehensively searched with no restricted language and region. The included randomized controlled trials (RCTs) compared taxanes-based combination therapy versus taxanes or other chemotherapy drugs. Statistical analysis was conducted using random-effect model, and the quality of RCTs was assessed using the tool of Cochrane Collaboration risk of bias.ResultsTwenty-six RCTs with a total of 8,236 advanced TNBC patients were included. Compared with taxanes monotherapy, taxanes-based combination therapy significantly prolonged progression-free survival (HR=0.79, 95%CI=0.74–0.83, I2= 0.0%, p=0.000) and overall survival (HR=0.88, 95%CI=0.82–0.94, I2= 9.3%, p=0.000) and increased the risk of vomiting (RR=1.26, 95%CI=1.07–1.48) and diarrhea (RR=1.82, 95%CI=1.22–2.70, I2= 90.3%, p=0.003). No statistical differences were observed in complete response rate (CRR), objective response rate (ORR), disease control rate (DCR), and progressive disease (PD) indexes (CRR: RR=1.38, 95%CI=0.96–1.99; ORR: RR=1.20, 95%CI=0.73–1.98; DCR: RR=1.09, 95%CI=1.00–1.19; PD: RR=0.70, 95%CI=0.47–1.04). Compared with other chemotherapy drugs, taxanes plus other chemotherapy drugs significantly reduced the incidence of vomiting (RR=0.60, 95%CI=0.44–0.84, I2= 12.3%, p=0.002) and neutropenia (RR=0.58, 95%CI=0.35–0.96, I2= 73.0%, p=0.036) during the treatment period.ConclusionsTaxanes-based combination therapy is evidently effective and well-tolerated in advanced TNBC, indicating that it might be a recommended option for treating advanced TNBC patients to some extent.Systematic Review Registration https://www.crd.york.ac.uk/PROSPERO/, identifier CRD42022337802.

Pembrolizumab plus Chemotherapy in Advanced Triple-Negative Breast Cancer

BackgroundIn an interim analysis of this phase 3 trial, the addition of pembrolizumab to chemotherapy resulted in longer progression-free survival than chemotherapy alone among patients with advanced triple-negative breast cancer whose tumors expressed programmed death ligand 1 (PD-L1) with a combined positive score (CPS; the number of PD-L1–staining tumor cells, lymphocytes, and macrophages, divided by the total number of viable tumor cells, multiplied by 100) of 10 or more. The results of the final analysis of overall survival have not been reported.MethodsWe randomly assigned patients with previously untreated locally recurrent inoperable or metastatic triple-negative breast cancer in a 2:1 ratio to receive pembrolizumab (200 mg) every 3 weeks plus the investigator’s choice of chemotherapy (nanoparticle albumin-bound paclitaxel, paclitaxel, or gemcitabine–carboplatin) or placebo plus chemotherapy. The primary end points were progression-free survival (reported previously) and overall survival among patients whose tumors expressed PD-L1 with a CPS of 10 or more (the CPS-10 subgroup), among patients whose tumors expressed PD-L1 with a CPS of 1 or more (the CPS-1 subgroup), and in the intention-to-treat population. Safety was also assessed.ResultsA total of 847 patients underwent randomization: 566 were assigned to the pembrolizumab–chemotherapy group, and 281 to the placebo–chemotherapy group. The median follow-up was 44.1 months. In the CPS-10 subgroup, the median overall survival was 23.0 months in the pembrolizumab–chemotherapy group and 16.1 months in the placebo–chemotherapy group (hazard ratio for death, 0.73; 95% confidence interval [CI], 0.55 to 0.95; two-sided P=0.0185 [criterion for significance met]); in the CPS-1 subgroup, the median overall survival was 17.6 and 16.0 months in the two groups, respectively (hazard ratio, 0.86; 95% CI, 0.72 to 1.04; two-sided P=0.1125 [not significant]); and in the intention-to-treat population, the median overall survival was 17.2 and 15.5 months, respectively (hazard ratio, 0.89; 95% CI, 0.76 to 1.05 [significance not tested]). Adverse events of grade 3, 4, or 5 that were related to the trial regimen occurred in 68.1% of the patients in the pembrolizumab–chemotherapy group and in 66.9% in the placebo–chemotherapy group, including death in 0.4% of the patients in the pembrolizumab–chemotherapy group and in no patients in the placebo–chemotherapy group.ConclusionsAmong patients with advanced triple-negative breast cancer whose tumors expressed PD-L1 with a CPS of 10 or more, the addition of pembrolizumab to chemotherapy resulted in significantly longer overall survival than chemotherapy alone. (Funded by Merck Sharp and Dohme; KEYNOTE-355 ClinicalTrials.gov number, NCT02819518.)

Immunotherapy and breast cancer: an overview.

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. 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. 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.

Current and New Novel Combination Treatments for Metastatic Triple-Negative Breast Cancer.

Triple-negative breast cancer (TNBC) has a worse prognosis and remains the most challenging breast cancer subtype to treat. This is largely related to the heterogeneity of this disease and the lack of reliable oncological targets. In this review, we discuss the current standard-of-care treatment options for metastatic TNBC, including recent advances with the use of immunotherapy, PARP inhibitors and antibody-drug conjugates. This review also explores new agents and novel combinations arising in the field for the treatment of advanced TNBC.

Blood levels of circulating tumor cells and factors of growth and progression in patients with locally advanced triple negative breast cancer receiving neoadjuvant chemotherapy

Active screening for early detection of breast cancer and new treatment options have significantly reduced mortality from breast cancer. However, a significant number of patients with non-metastatic breast cancer have advanced disease at the time of diagnosis. Triple negative breast cancer (TNBC) is a specific cancer subtype characterized with deep invasiveness, high metastatic potential, tendency to recurrence, and poor prognosis. It is known to have no application to endocrine therapy or anti-HER2 therapy. The search for new markers is an important direction in predicting the course of the disease and the effectiveness of treatment, monitoring progression and relapse. This study presents an analysis of blood levels of factors of growth and progression (TGFβ, TGFR2, TNFα. TNFαR1, TNFαR2, CD-44 and MMP-9) and circulating tumor cells (CTCs) in 56 patients with locally advancer TNBC after complex treatment. We identified a complex of growth and progression factors that determines the sensitivity and resistance to chemotherapy in all BC subtypes. Decreased levels of TGF-β, TNFα, MMP-9, CD-44 and CTCs after neoadjuvant chemotherapy determine further remission during 3 years. On the contrary, stabilization or elevation of these parameters leads to an early tumor progression.

MO19-3 PD-L1 expression in patients with HER2-negative advanced breast cancer: A multicenter retrospective study

Programmed death-ligand 1 (PD-L1) overexpression was seen in about 40% of triple-negative advanced breast cancer (TN-ABC) patients (pts). However, PD-L1 status in HER2-negative (HER2-ve) ABC pts is poorly understood, and no biomarker related to chemotherapy (CT) for HER2-ve ABC pts excluding PD-L1 in TN-ABC has been clarified. We evaluated PD-L1 status using SP142 and explored biomarkers for first-line (1L) paclitaxel + bevacizumab (PB) therapy using immune signatures in HER2-ve ABC pts.

Integrating Immunotherapy Into the Treatment Landscape for Patients With Triple-Negative Breast Cancer.

Triple-negative breast cancer (TNBC) is the most aggressive histologic subtype of breast cancer for which, until recently, treatment options have been limited to chemotherapy. In recent years, an improved understanding of the importance of tumor-infiltrating lymphocytes and the tumor microenvironment in TNBC has led to investigation of immune checkpoint inhibitors for treatment. There is now evidence from several randomized controlled trials that supports the addition of immune checkpoint inhibitors to first-line treatment of advanced TNBC and to neoadjuvant chemotherapy for stage II-III TNBC. In parallel, the PARP inhibitors have emerged as a targeted therapy option for patients with HER2-negative breast cancer harboring mutations in BRCA1, BRCA2, and PALB2. Here, we review the recent clinical trials that inform the integration of immune checkpoint inhibitors into treatments for TNBC and discuss ongoing challenges-including patient selection, management of resistance to post-checkpoint inhibitor therapy, and combining immunotherapy with targeted therapies, including PARP inhibitors.

Dynamics of tumor-associated macrophages in a quantitative systems pharmacology model of immunotherapy in triple-negative breast cancer

SummaryQuantitative systems pharmacology (QSP) modeling is an emerging mechanistic computational approach that couples drug pharmacokinetics/pharmacodynamics and the course of disease progression. It has begun to play important roles in drug development for complex diseases such as cancer, including triple-negative breast cancer (TNBC). The combination of the anti-PD-L1 antibody atezolizumab and nab-paclitaxel has shown clinical activity in advanced TNBC with PD-L1-positive tumor-infiltrating immune cells. As tumor-associated macrophages (TAMs) serve as major contributors to the immuno-suppressive tumor microenvironment, we incorporated the dynamics of TAMs into our previously published QSP model to investigate their impact on cancer treatment. We show that through proper calibration, the model captures the macrophage heterogeneity in the tumor microenvironment while maintaining its predictive power of the trial results at the population level. Despite its high mechanistic complexity, the modularized QSP platform can be readily reproduced, expanded for new species of interest, and applied in clinical trial simulation.

Significance of the effects of chemotherapy on programmed death-ligand 1 expression in triple-negative breast cancer.

Atezolizumab has been approved as an antibody against programmed death-ligand 1 (PD-L1)-positive immune cells in patients with advanced or recurrent triple-negative breast cancer. However, the optimal timing to examine PD-L1 expression remains controversial. We retrospectively researched PD-L1 positivity rates in biopsy, surgical and recurrent specimens from patients with triple-negative breast cancer treated with neoadjuvant chemotherapy. We also examined alterations in PD-L1 and their meaning. In total, 35 triple-negative breast cancer biopsy specimens obtained before neoadjuvant chemotherapy, 20 corresponding specimens obtained after neoadjuvant chemotherapy and 5 corresponding recurrent specimens were obtained. We examined PD-L1 immunohistochemistry on tumor cells and tumor-infiltrating immune cells using SP142 antibody. In comparison with specimens obtained before neoadjuvant chemotherapy, PD-L1 expression randomly changed in immune cells after neoadjuvant chemotherapy, but PD-L1 expression was significantly reduced in tumor cells. Pre-neoadjuvant chemotherapy specimens with low PD-L1 expression (PD-L1 scores of ≤1 for both immune cells and tumor cells) were linked to better disease-free survival (P<0.001) and overall survival (P<0.001) than the other specimens. This is the first study to evaluate PD-L1 expression both before and after chemotherapy in breast cancer and examine its relationship with prognosis. The results suggest that the PD-L1 level may be useful for predicting the prognosis of patients with triple-negative breast cancer who do not have pathological complete responses to neoadjuvant chemotherapy.

Research progress on immunotherapy in triple‑negative breast cancer (Review).

Triple-negative breast cancer (TNBC) is a highly heterogeneous and aggressive malignancy. Due to the absence of estrogen receptors and progesterone receptors and the lack of overexpression of human epidermal growth factor receptor 2, TNBC responds poorly to endocrine and targeted therapies. As a neoadjuvant therapy, chemotherapy is usually the only option for TNBC; however, chemotherapy may induce tumor resistance. The emergence of immunotherapy as an adjuvant therapy is expected to make up for the deficiency of chemotherapy. Most of the research on immunotherapies has been performed on advanced metastatic TNBC, which has provided significant clinical benefits. In the present review, possible immunotherapy targets and ongoing immunotherapy strategies were discussed. In addition, progress in research on immune checkpoint inhibitors in early TNBC was outlined.

RWD55 Systemic Antineoplastic Treatment Utilization Among Patients with Advanced Triple Negative Breast Cancer across Large Community Health Systems in the US

Community health systems (CHS) in the US play a large role in the care of patients with cancer, with over 50% of patients with cancer cared for in CHS. The systemic treatments used among patients with advanced triple negative breast cancer (aTNBC) seen in these CHS are not widely published. This analysis describes the systemic treatment utilization of these patients treated across a sample of CHSs.

SP142 PD-L1 Assays in Multiple Samples from the Same Patients with Early or Advanced Triple-Negative Breast Cancer.

Simple SummaryThe IMpassion130 trial suggests that metastatic triple-negative breast cancer (TNBC) patients with PD-L1+ derived a clinical benefit from atezolizumab-combined treatment regardless of the sample collection time or origin. Therefore, if the PD-L1 test is positive at least once in multiple samples, the patient could have an opportunity to receive atezolizumab-based treatments. We aimed to know whether multiple PD-L1 testing might increase a rate of PD-L1+ in patients with TNBC. SP142 PD-L1 assays were performed in multiple samples from 77 patients in early TNBC. Multiple PD-L1 test using multiple samples raised the PD-L1+ rate more than a single biopsied sample test (68.8% vs. 37.6%, p = 0.00002). Among the group with metastatic TNBC treated with atezolizumab and nab-paclitaxel, PD-L1 assays were performed at least twice in 8/12 patients; 5/8 had heterogeneous results of PD-L1 assays. Consequently, a vigorous PD-L1 test using multiple samples was considered necessary in TNBC because a single test might be insufficient to represent the PD-L1 status.Purpose: The discernible PD-L1 staining of tumor-infiltrating lymphocytes occupying ≥ 1% of the tumor area is considered SP142 PD-L1 positive for atezolizumab, and the PD-L1 status of multiple samples within a single patient could be discrepant. In this study, we evaluated the PD-L1 status by using the SP142 clone in serially collected matched samples from the same individuals with early or metastatic triple-negative breast cancer (TNBC). Method: the SP142 PD-L1 assay was performed using biopsies and surgical specimens from 77 patients with early TNBC. Among these patients, 47 underwent upfront surgery, and 30 underwent neoadjuvant chemotherapy (NAC) between biopsy and surgery. PD-L1 assays were performed at least twice in 8/12 (66.7%) patients with metastatic TNBC treated with atezolizumab and nab-paclitaxel. Results: Of the 47 patients who underwent upfront surgery, 15/47 (31.9%) had PD-L1+ on biopsied samples. PD-L1+ rates in the biopsy and surgical specimens increased to 66.0% (33 of 47) after subsequent surgery. Similarly, in the 30 patients with residual invasive cancer who underwent neoadjuvant chemotherapy, the PD-L1+ rate increased from 46.6% at baseline to 74.2% after surgery. In the 77 patients with early TNBC, multiple PD-L1 testing in the biopsies and surgical specimens significantly increased the number of patients with PD-L1+ compared with the number of patients with PD-L1+ assessed with initial biopsy samples alone (68.8% vs. 37.6%; p = 0.00002). Among the metastatic TNBC patients, those with constant PD-L1+ over 1% positivity in multiple samples showed a response which was longer than 12 months. Conclusions: Our findings reveal the heterogeneous SP142 PD-L1 expression in TNBC and suggest that PD-L1 evaluation in baseline biopsy might be insufficient to represent the PD-L1 status of whole tumors. In TNBC, vigorous PD-L1 examination using multiple available tumor samples could identify more patients eligible for immune checkpoint blockade.

Progress and Prospect of Immunotherapy for Triple-Negative Breast Cancer.

Breast cancer is the most commonly diagnosed cancer (estimated 2.3 million new cases in 2020) and the leading cause of cancer death (estimated 685,000 deaths in 2020) in women globally. Breast cancers have been categorized into four major molecular subtypes based on the immunohistochemistry (IHC) expression of classic hormone and growth factor receptors including the estrogen receptor (ER), progesterone receptor (PR), and human epidermal growth factor receptor 2 (HER2), as well as a proliferation marker Ki-67 protein expression. Triple-negative breast cancer (TNBC), a breast cancer subtype lacking ER, PR, and HER2 expression, is associated with a high metastatic potential and poor prognosis. TNBC accounts for approximately only 15%–20% of new breast cancer diagnoses; it is responsible for most breast cancer–related deaths due to the lack of targeted treatment options for this patient population, and currently, systemic chemotherapy, radiation, and surgical excision remain the major treatment modalities for these patients with TNBC. Although breast cancer patients in general do not have a robust response to the immunotherapy, a subset of TNBC has been demonstrated to have high tumor mutation burden and high tumor-infiltrating lymphocytes, resembling the features observed on melanoma or lung cancers, which can benefit from the treatment of immune checkpoint inhibitors (ICIs). Therefore, the immunogenic nature of this aggressive disease has presented an opportunity for the development of TNBC-targeting immunotherapies. The recent US Food and Drug Administration approval of atezolizumab in combination with the chemotherapeutic agent nab-paclitaxel for the treatment of PD-L1-positive unresectable, locally advanced, or metastatic TNBC has led to a new era of immunotherapy in TNBC treatment. In addition, immunotherapy becomes an active research area, both in the cancer biology field and in the oncology field. In this review, we will extend our coverage on recent discoveries in preclinical research and early results in clinical trials from immune molecule-based therapy including cytokines, monoclonal antibodies, antibody–drug conjugates, bi-specific or tri-specific antibodies, ICIs, and neoantigen cancer vaccines; oncolytic virus-based therapies and adoptive immune cell transfer–based therapies including TIL, chimeric antigen receptor-T (CAR-T), CAR-NK, CAR-M, and T-cell receptor-T. In the end, we will list a series of the challenges and opportunities in immunotherapy prospectively and reveal novel technologies such as high-throughput single-cell sequencing and CRISPR gene editing-based screening to generate new knowledges of immunotherapy.

Abstract LB085: ATYR2810, a fully humanized monoclonal antibody targeting the VEGF-NRP2 pathway sensitizes highly aggressive and chemoresistant TNBC subtypes to chemotherapy

Abstract Introduction: Triple negative breast cancer (TNBC) represents 15% of all breast cancers, and is a notably aggressive subtype that is prone to early recurrence following initial diagnosis with a median survival of only 9 months following recurrence. One of the few treatment options for patients with advanced and metastatic TNBC is platinum-based chemotherapy, however not all tumors respond, and those that do often become refractory during the course of treatment. The cell surface receptor Neuropilin-2 (NRP2), which acts as a co-receptor for vascular endothelial growth factors (VEGFs), has been shown to be both highly expressed and associated with therapeutic resistance in TNBC. NRP2 also serves as a co-receptor for semaphorins, which may play tumor-suppressor functions in breast cancer. We have previously demonstrated that ATYR2810, a highly specific humanized monoclonal antibody which effectively blocks NRP2/VEGF signaling without disrupting NRP2/Semaphorin 3F signaling, down-regulated epithelial-mesenchymal transition (EMT) genes such as ZEB1 and sensitizes TNBC to chemotherapy both in vitro and in vivo. Results: In this study we have further characterized the breast cancer subtypes that are most responsive to ATYR2810 treatment. Using in vitro 3D colony formation assays (CFAs), we have interrogated ~15 breast cancer cell lines covering luminal, HER2+ and various TNBC subtypes, for responsiveness to ATYR2810 treatment in combination with chemotherapy. All responsive cell lines were associated with the more aggressive subtypes of TNBC such as BL2 (basal-like 2), ML (mesenchymal-like) and MSL (mesenchymal-stem like) subtypes. Additionally, we screened five patient derived xenografts (PDXs) and again found that the responsive PDXs were associated with the more aggressive and chemoresistant subtypes of TNBC. To gain insight into the potential mechanism for enhanced chemosensitivity by ATYR2810 treatment, we performed RNAseq on the PDX tumors. Interestingly, the chemokine receptor CXCR4, which is known to promote drug resistance and tumorigenic potential, was found to be significantly downregulated in responder PDX tumors treated with ATYR2810 in combination with cisplatin as compared to those treated with cisplatin alone. Further, gene set enrichment analysis (GSEA) showed that CXCR4 was found in numerous downregulated pathways enriched in the PDX responder tumors treated with ATYR2810/cisplatin, suggesting that CXCR4 may be driving the responder phenotype of the PDXs. Flow cytometry analysis of TNBC cells treated with ATYR2810 monotherapy in vitro resulted in a reduced frequency of cells expressing CXCR4. Furthermore, ATYR2810 monotherapy inhibited spontaneous lung metastasis in experimental models of mesenchymal TNBC. Conclusion: Taken together, our data suggest that ATYR2810 enhances chemosensitivity in highly aggressive TNBC subtypes, and that this response may be mediated through the downregulation of genes known to be associated with aggressive cancer states such as ZEB1 and CXCR4. ATYR2810 may therefore serve as a novel therapeutic agent for the treatment of advanced and metastatic TNBC and potentially other aggressive cancer types. Zhiwen Xu and Alison Barber are co-first authors of this abstract. Citation Format: Zhiwen Xu, Alison Barber, Christoph Burkart, Hira Lal Goel, Justin Rahman, Kristina Hamel, Zachary Fogassy, Lisa Eide, Clara Polizzi, Jasmine Stamps, Sofia Klopp Savino, Luke Burman, Esther Chong, Suzanne Paz, Arthur M. Mercurio, Leslie A. Nangle. ATYR2810, a fully humanized monoclonal antibody targeting the VEGF-NRP2 pathway sensitizes highly aggressive and chemoresistant TNBC subtypes to chemotherapy [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr LB085.