Abstract OT1-02-04: SWOG S1418/NRG -BR006: A randomized, phase III trial to evaluate the efficacy and safety of MK-3475 as adjuvant therapy for triple receptor-negative breast cancer with > 1 cm residual invasive cancer or positive lymph nodes (>pN1mic) after neoadjuvant chemotherapy

Shifting Paradigms in TNBC Treatment: Emerging Alternatives to Capecitabine in the Post-Neoadjuvant Setting

BACKGROUND

Triple-negative breast cancer (TNBC) remains a clinically challenging subtype due to its aggressive nature and limited treatment options post-neoadjuvant failure. Historically, capecitabine has been the cornerstone of adjuvant therapy for TNBC patients not achieving a pathological complete response (pCR). However, the integration of new modalities such as immunotherapy and PARP inhibitors has prompted a re-evaluation of traditional post-neoadjuvant approaches.

METHODS

This review synthesizes data from pivotal clinical trials and meta-analyses to evaluate the efficacy of emerging therapies in the post-neoadjuvant setting. We focus on the role of immune checkpoint inhibitors (ICIs), PARP inhibitors (PARPis), and antibody-drug conjugates (ADCs) alongside or in place of capecitabine in TNBC treatment paradigms.

RESULTS

The addition of ICIs like pembrolizumab to neoadjuvant regimens has shown increased pCR rates and improved event-free survival, posing new questions about optimal post-neoadjuvant therapies. Similarly, PARPis have demonstrated efficacy in BRCA-mutated TNBC populations, with significant improvements in disease-free survival (DFS) and overall survival (OS). Emerging studies on ADCs further complicate the adjuvant landscape, offering potentially efficacious alternatives to capecitabine, especially in patients with residual disease after neoadjuvant therapy.

DISCUSSION

The challenge remains to integrate these new treatments into clinical practice effectively, considering factors such as drug resistance, patient-specific characteristics, and socio-economic barriers. This review discusses the implications of these therapies and suggests a future direction focused on personalized medicine approaches in TNBC.

CONCLUSIONS

As the treatment landscape for TNBC evolves, the role of capecitabine is being critically examined. While it remains a viable option for certain patient groups, the introduction of ICIs, PARPis, and ADCs offers promising alternatives that could redefine adjuvant therapy standards. Ongoing and future trials will be pivotal in determining the optimal therapeutic strategies for TNBC patients with residual disease post-neoadjuvant therapy.

Adjuvant nivolumab, capecitabine or the combination in patients with residual triple-negative breast cancer: the OXEL randomized phase II study

Chemotherapy and immune checkpoint inhibitors have a role in the post-neoadjuvant setting in patients with triple-negative breast cancer (TNBC). However, the effects of nivolumab, a checkpoint inhibitor, capecitabine, or the combination in changing peripheral immunoscore (PIS) remains unclear. This open-label randomized phase II OXEL study (NCT03487666) aimed to assess the immunologic effects of nivolumab, capecitabine, or the combination in terms of the change in PIS (primary endpoint). Secondary endpoints included the presence of ctDNA, toxicity, clinical outcomes at 2-years and association of ctDNA and PIS with clinical outcomes. Forty-five women with TNBC and residual invasive disease after standard neoadjuvant chemotherapy were randomized to nivolumab, capecitabine, or the combination. Here we show that a combination of nivolumab plus capecitabine leads to a greater increase in PIS from baseline to week 6 (91%) compared with nivolumab (47%) or capecitabine (53%) alone (log-rank p = 0.08), meeting the pre-specified primary endpoint. In addition, the presence of circulating tumor DNA (ctDNA) is associated with disease recurrence, with no new safety signals in the combination arm. Our results provide efficacy and safety data on this combination in TNBC and support further development of PIS and ctDNA analyses to identify patients at high risk of recurrence.

Immunotherapy for Early-Stage Triple Negative Breast Cancer: Is Earlier Better?

PURPOSE OF REVIEW

In this narrative review, we discuss the optimal timing of immune checkpoint inhibitors (ICI) in early triple negative breast cancer (TNBC), the landscape of predictive biomarkers for the use of immunotherapy, and the mounting literature suggesting a benefit for an early use of ICI.

RECENT FINDINGS

TNBC is associated with a poor prognosis relative to other breast cancer subtypes, and until recently, the treatment of TNBC was limited to cytotoxic chemotherapy. In 2021, the immune-checkpoint inhibitor, pembrolizumab, was approved in combination with neoadjuvant chemotherapy for patients with high-risk early stage TNBC. This approval changed the treatment paradigm of early TNBC concomitantly raised several challenges in clinical practice, pertaining to patient selection, toxicity management, and post-neoadjuvant treatment, among others. The introduction of neoadjuvant chemoimmunotherapy has transformed the treatment landscape for early TNBC. However, several challenges, including patient selection, toxicity management, and the identification of predictive biomarkers, need to be addressed. Future research should focus on refining the timing and duration of immunotherapy, optimizing the chemotherapy partner, and exploring novel predictive biomarkers of response or toxicity.

Adjuvant nivolumab, capecitabine or the combination in patients with residual triple-negative breast cancer: the OXEL randomized phase II study

Chemotherapy and immune checkpoint inhibitors have a role in the post-neoadjuvant setting in patients with triple-negative breast cancer (TNBC). However, the effects of nivolumab, a checkpoint inhibitor, capecitabine, or the combination in changing peripheral immunoscore (PIS) remains unclear. This open-label randomized phase II OXEL study (NCT03487666) aimed to assess the immunologic effects of nivolumab, capecitabine, or the combination in terms of the change in PIS (primary endpoint). Secondary endpoints include the presence of ctDNA, toxicity, clinical outcomes at 2-years and association of ctDNA and PIS with clinical outcomes. Forty-five women with TNBC and residual invasive disease after standard neoadjuvant chemotherapy were randomized to nivolumab, capecitabine, or the combination. Here we show that a combination of nivolumab plus capecitabine leads to a greater increase in PIS from baseline to week 6 (91%) compared with nivolumab (47%) or capecitabine (53%) alone (log-rank p = 0.08), meeting the pre-specified primary endpoint. In addition, the presence of circulating tumor DNA (ctDNA) was associated with disease recurrence, with no new safety signals in the combination arm. Our results provide efficacy and safety data on this combination in TNBC and support further development of PIS and ctDNA analyses to identify patients at high risk of recurrence.

Advances in the Management of Early-Stage Triple-Negative Breast Cancer

Triple-negative breast cancer (TNBC) is a subtype of breast cancer with both inter- and intratumor heterogeneity, thought to result in a more aggressive course and worse outcomes. Neoadjuvant therapy (NAT) has become the preferred treatment modality of early-stage TNBC as it allows for the downstaging of tumors in the breast and axilla, monitoring early treatment response, and most importantly, provides important prognostic information that is essential to determining post-surgical therapies to improve outcomes. It focuses on combinations of systemic drugs to optimize pathologic complete response (pCR). Excellent response to NAT has allowed surgical de-escalation in ideal candidates. Further, treatment algorithms guide the systemic management of patients based on their pCR status following surgery. The expanding knowledge of molecular pathways, genomic sequencing, and the immunological profile of TNBC has led to the use of immune checkpoint inhibitors and targeted agents, including PARP inhibitors, further revolutionizing the therapeutic landscape of this clinical entity. However, subgroups most likely to benefit from these novel approaches in TNBC remain elusive and are being extensively studied. In this review, we describe current practices and promising therapeutic options on the horizon for TNBC, surgical advances, and future trends in molecular determinants of response to therapy in early-stage TNBC.

Current Treatment Landscape for Early Triple-Negative Breast Cancer (TNBC)

Triple-negative breast cancer (TNBC) accounts for 15-20% of all breast cancers and is characterized by an aggressive nature and a high rate of recurrence despite neoadjuvant and adjuvant chemotherapy. Although novel agents are constantly being introduced for the treatment of breast cancer, conventional cytotoxic chemotherapy based on anthracyclines and taxanes is the mainstay treatment option for TNBC. Based on CTNeoBC pooled analysis data, the achievement of pathologic CR (pCR) in TNBC is directly linked to improved survival outcomes. Therefore, the treatment paradigm for early TNBC has shifted to neoadjuvant treatment, and the escalation of neoadjuvant chemotherapy to improve the pCR rate and the addition of post-neoadjuvant chemotherapy to control the residual disease have been investigated. In this article, we review the current treatment landscape for early TNBC, from standard cytotoxic chemotherapy to recent data on immune checkpoint inhibitors, capecitabine, and olaparib.

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

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

Immune checkpoint inhibition in early-stage triple-negative breast cancer

INTRODUCTION

Breast cancer cells can evade immune recognition by upregulating programmed death-ligand 1 (PD-L1) leading to decreased T cell function. Anti-PD-1 agents, like pembrolizumab, and anti-PD-L1 agents, such as atezolizumab and durvalumab, in combination with chemotherapy were found to have efficacy in metastatic triple-negative breast cancer (TNBC). With sub-optimal long-term outcomes in early-stage TNBC, this combination of immune checkpoint inhibition with chemotherapy was subsequently investigated. A robust immune microenvironment and extensive tumor antigen exposure in early-stage breast cancer is believed to facilitate response to checkpoint inhibitors.

AREAS COVERED

This review focuses on studies that assess the role of neoadjuvant immune checkpoint inhibition along with chemotherapy. The results of key phase I, II and III trials using checkpoint inhibitors in early-stage breast cancer (ESBC) are reviewed along with foundational data from metastatic TNBC, including the role of biomarkers in predicting response to immunotherapy.

EXPERT OPINION

Despite a clear role for neoadjuvant immune checkpoint inhibition in TNBC, many questions remain. The benefit of these agents in the neoadjuvant versus adjuvant setting is unclear and immune-related toxicity is a major concern. Additional studies are needed to elucidate which immune checkpoint inhibitor is most efficacious and best tolerated in early-stage TNBC.

The landscape of systemic therapy for early stage triple negative breast cancer

INTRODUCTION

Triple negative breast cancer (TNBC) is the most aggressive subtype of breast cancer with higher risk of disease recurrence and mortality than other breast cancer subtypes. Historically, chemotherapy has been the primary systemic treatment for early stage TNBC. Recent developments in immune checkpoint inhibitors (ICIs) and novel therapeutic agents have transformed the treatment of TNBC.

AREAS COVERED

This review provides a comprehensive overview of the current evidence on treatment of early stage TNBC. We highlight the incorporation of ICIs and other targeted therapies in (neo)adjuvant treatment and the ongoing development of novel therapeutic agents.

EXPERT OPINION

The landscape of early TNBC treatment is rapidly evolving which has given rise to the introduction of ICIs and PARP inhibitors into the systemic therapy. Despite modest improvement in pathologic complete response (pCR) rate, ICI plus chemotherapy significantly improves long-term outcomes and is now used in (neo)adjuvant treatment of patients with TNBC and high risk for disease recurrence. Capecitabine remains the standard adjuvant treatment for residual disease, with olaparib being an option for patients with germline BRCA1/2 mutations. Early detection of minimal residual disease may identify patients requiring additional therapy to prevent recurrence.

Triple-Negative Breast Cancer: A Review of Current Curative Intent Therapies

Breast cancer is the most commonly diagnosed malignancy in women, with triple-negative breast cancer (TNBC) accounting for 10–20% of cases. Historically, fewer treatment options have existed for this subtype of breast cancer, with cytotoxic chemotherapy playing a predominant role. This article aims to review the current treatment paradigm for curative-intent TNBC, while also reviewing potential future developments in this landscape. In addition to chemotherapy, recent advances in the understanding of the molecular biology of TNBC have led to promising new studies of targeted and immune checkpoint inhibitor therapies in the curative-intent setting. The appropriate selection of TNBC patient subgroups with a higher likelihood of benefit from treatment is critical to identify the best treatment approach.

Immunotherapy for triple negative breast cancer: How can pathologic responses to experimental drugs in early-stage disease be enhanced?

INTRODUCTION

: The treatment landscape of early triple negative breast cancer (TNBC) has recently expanded after the Food and Drug Administration (FDA) approval of pembrolizumab in combination with neoadjuvant chemotherapy. The addition of this immune checkpoint inhibitor (ICI) has shown to significantly increased pathological complete response (pCR) rate and event free survival (EFS) in the KEYNOTE-522 phase 3 trial. Several additional studies are ongoing with the goal of further improving outcomes and achieving an optimal integration of ICIs in the treatment of TNBC.

AREAS COVERED

: The article examines pCR and survival rates in TNBC. It appraises clinical trials investigating neoadjuvant ICIs for TNBC and the improvement of pCR rates (biomarker-driven escalation of treatment, optimization of chemotherapy backbone and addition of locoregional treatments or innovative agents). Insights on the role of pCR as surrogate endpoint and the possibility of enhancing pCR rates for women affected by early TNBC are offered.

EXPERT OPINION

: The pharmacopoeia of early TNBC is growing and becoming more heterogeneous with the advent of ICIs; to enhance the clinical benefit of patients, it is necessary to develop response endpoints that consider the mechanism of action of experimental drugs, to optimize patient selection through validated biomarkers, and to compare the most promising treatment strategies in randomized clinical trials.

Current advances in immune checkpoint inhibitor combinations with radiation therapy or cryotherapy for breast cancer

PURPOSE

Immune checkpoint inhibition (ICI) has demonstrated clinically significant efficacy when combined with chemotherapy in triple negative breast cancer (TNBC). Although many patients derived benefit, others do not respond to immunotherapy, therefore relying upon innovative combinations to enhance response. Local therapies such as radiation therapy (RT) and cryotherapy are immunogenic and potentially optimize responses to immunotherapy. Strategies combining these therapies and ICI are actively under investigation. This review will describe the rationale for combining ICI with targeted local therapies in breast cancer.

METHODS

A literature search was performed to identify pre-clinical and clinical studies assessing ICI combined with RT or cryotherapy published as of August 2021 using PubMed and ClinicalTrials.gov.

RESULTS

Published studies of ICI with RT and IPI have demonstrated safety and signals of early efficacy.

CONCLUSION

RT and cryotherapy are local therapies that can be integrated safely with ICI and has shown promise in early trials. Randomized phase II studies testing both of these approaches, such as P-RAD (NCT04443348) and ipilimumab/nivolumab/cryoablation for TNBC (NCT03546686) are current enrolling. The results of these studies are paramount as they will provide long term data on the safety and efficacy of these regimens.

Society for Immunotherapy of Cancer (SITC) clinical practice guideline on immunotherapy for the treatment of breast cancer

Breast cancer has historically been a disease for which immunotherapy was largely unavailable. Recently, the use of immune checkpoint inhibitors (ICIs) in combination with chemotherapy for the treatment of advanced/metastatic triple-negative breast cancer (TNBC) has demonstrated efficacy, including longer progression-free survival and increased overall survival in subsets of patients. Based on clinical benefit in randomized trials, ICIs in combination with chemotherapy for the treatment of some patients with advanced/metastatic TNBC have been approved by the United States (US) Food and Drug Administration (FDA), expanding options for patients. Ongoing questions remain, however, about the optimal chemotherapy backbone for immunotherapy, appropriate biomarker-based selection of patients for treatment, the optimal strategy for immunotherapy treatment in earlier stage disease, and potential use in histological subtypes other than TNBC. To provide guidance to the oncology community on these and other important concerns, the Society for Immunotherapy of Cancer (SITC) convened a multidisciplinary panel of experts to develop a clinical practice guideline (CPG). The expert panel drew upon the published literature as well as their clinical experience to develop recommendations for healthcare professionals on these important aspects of immunotherapeutic treatment for breast cancer, including diagnostic testing, treatment planning, immune-related adverse events (irAEs), and patient quality of life (QOL) considerations. The evidence-based and consensus-based recommendations in this CPG are intended to give guidance to cancer care providers treating patients with breast cancer.

Results of a Randomized Phase IIb Trial of Nelipepimut-S + Trastuzumab versus Trastuzumab to Prevent Recurrences in Patients with High-Risk HER2 Low-Expressing Breast Cancer

PURPOSE

Preclinical data provide evidence for synergism between HER2-targeted peptide vaccines and trastuzumab. The efficacy of this combination was evaluated in patients with HER2 low-expressing breast cancer in the adjuvant setting.

PATIENTS AND METHODS

A phase IIb, multicenter, randomized, single-blinded, controlled trial enrolled disease-free patients after standard therapy completion (NCT01570036). Eligible patients were HLA-A2, A3, A24, and/or A26+, and had HER2 IHC 1+/2+, FISH nonamplified breast cancer, that was node positive and/or hormone receptor-negative [triple-negative breast cancer (TNBC)]. Patients received trastuzumab for 1 year and were randomized to placebo (GM-CSF, control) or nelipepimut-S (NPS) with GM-CSF. Primary outcome was 24-month disease-free survival (DFS). Secondary outcomes were 36-month DFS, safety, and immunologic response.

RESULTS

Overall, 275 patients were randomized; 136 received NPS with GM-CSF, and 139 received placebo with GM-CSF. There were no clinicopathologic differences between groups. Concurrent trastuzumab and NPS with GM-CSF was safe with no additional overall or cardiac toxicity compared with control. At median follow-up of 25.7 (interquartile range, 18.4-32.7) months, estimated DFS did not significantly differ between NPS and control [HR, 0.62; 95% confidence interval (CI), 0.31-1.25; P = 0.18]. In a planned exploratory analysis of patients with TNBC, DFS was improved for NPS versus control (HR, 0.26; 95% CI, 0.08-0.81, P = 0.01).

CONCLUSIONS

The combination of NPS with trastuzumab is safe. In HER2 low-expressing breast cancer, no significant difference in DFS was seen in the intention-to-treat analysis; however, significant clinical benefit was seen in patients with TNBC. These findings warrant further investigation in a phase III randomized trial.