Phase I/II trial of neoadjuvant sunitinib administered with weekly paclitaxel/carboplatin in patients with locally advanced triple-negative breast cancer

Small molecule agents for triple negative breast cancer: Current status and future prospects

Triple-negative breast cancer (TNBC) is a subtype of breast cancer with poor prognosis. The number of cases increased by 2.26 million in 2020, making it the most commonly diagnosed cancer type in the world. TNBCs lack hormone receptor (HR) and human epidermal growth factor 2 (HER2), which limits treatment options. Currently, paclitaxel-based drugs combined with other chemotherapeutics remain the main treatment for TNBC. There is currently no consensus on the best therapeutic regimen for TNBC. However, there have been successful clinical trials exploring large-molecule monoclonal antibodies, small-molecule targeted drugs, and novel antibody-drug conjugate (ADC). Although monoclonal antibodies have produced clinical success, their large molecular weight can limit therapeutic benefits. It is worth noting that in the past 30 years, the FDA has approved small molecule drugs for HER2-positive breast cancers. The lack of effective targets and the occurrence of drug resistance pose significant challenges in the treatment of TNBC. To improve the prognosis of TNBC, it is crucial to search for effective targets and to overcome drug resistance. This review examines the clinical efficacy, adverse effects, resistance mechanisms, and potential solutions of targeted small molecule drugs in both monotherapies and combination therapies. New therapeutic targets, including nuclear export protein 1 (XPO1) and hedgehog (Hh), are emerging as potential options for researchers and become integrated into clinical trials for TNBC. Additionally, there is growing interest in the potential of targeted protein degradation chimeras (PROTACs), degraders of rogue proteins, as a future therapy direction. This review provides potentially valuable insights with clinical implications.

Transdermal delivery of brucine-encapsulated liposomes significantly enhances anti-tumor outcomes in treating triple-negative breast cancer

Triple-negative breast cancer (TNBC) is always the most challenging breast cancer subtype. Herein, brucine, encapsulated in peptide-modified liposomes, was proposed for treating TNBC by transdermal delivery. For the TD peptide-modified brucine-loaded liposome (Bru-TD-Lip) we developed, it presents high encapsulation efficiency of brucine and stability. In vitro, Bru-TD-Lip shows the enhanced percutaneous permeability of brucine, is able to readily enter TNBC cells, and significantly inhibits the proliferation, migration, and invasion of these cells. In vivo, through transdermal delivery, Bru-TD-Lip presents good biosafety and anti-tumor efficacy. The transdermal delivery of Bru-TD-Lip effectively targets and inhibits subcutaneous mammary carcinogenesis in female nude mice. Compared with oral administration, the transdermal delivery significantly reduces the damage of brucine to major organs and enhances the antitumor outcomes of brucine in treating TNBC. This study provides a new therapeutic strategy for treating triple-negative breast cancer by brucine.

Diverse roles of tumor-stromal PDGFB-to-PDGFRβ signaling in breast cancer growth and metastasis

Over the last couple of decades, it has become increasingly apparent that the tumor microenvironment (TME) mediates every step of cancer progression and solid tumors are only able to metastasize with a permissive TME. This intricate interaction of cancer cells with their surrounding TME, or stroma, is becoming more understood with an ever greater knowledge of tumor-stromal signaling pairs such as platelet-derived growth factors (PDGF) and their cognate receptors. We and others have focused our research efforts on understanding how tumor-derived PDGFB activates platelet-derived growth factor receptor beta (PDGFRβ) signaling specifically in the breast cancer TME. In this chapter, we broadly discuss PDGF and PDGFR expression patterns and signaling in normal physiology and breast cancer. We then detail the expansive roles played by the PDGFB-to-PDGFRβ signaling pathway in modulating breast tumor growth and metastasis with a focus on specific cellular populations within the TME, which are responsive to tumor-derived PDGFB. Given the increasingly appreciated importance of PDGFB-to-PDGFRβ signaling in breast cancer progression, specifically in promoting metastasis, we end by discussing how therapeutic targeting of PDGFB-to-PDGFRβ signaling holds great promise for improving current breast cancer treatment strategies.

Targeting Angiogenesis in Breast Cancer: Current Evidence and Future Perspectives of Novel Anti-Angiogenic Approaches

Angiogenesis is a vital process for the growth and dissemination of solid cancers. Numerous molecular pathways are known to drive angiogenic switch in cancer cells promoting the growth of new blood vessels and increased incidence of distant metastasis. Several angiogenesis inhibitors are clinically available for the treatment of different types of advanced solid cancers. These inhibitors mostly belong to monoclonal antibodies or small-molecule tyrosine kinase inhibitors targeting the classical vascular endothelial growth factor (VEGF) and its receptors. Nevertheless, breast cancer is one example of solid tumors that had constantly failed to respond to angiogenesis inhibitors in terms of improved survival outcomes of patients. Accordingly, it is of paramount importance to assess the molecular mechanisms driving angiogenic signaling in breast cancer to explore suitable drug targets that can be further investigated in preclinical and clinical settings. This review summarizes the current evidence for the effect of clinically available anti-angiogenic drugs in breast cancer treatment. Further, major mechanisms associated with intrinsic or acquired resistance to anti-VEGF therapy are discussed. The review also describes evidence from preclinical and clinical studies on targeting novel non-VEGF angiogenic pathways in breast cancer and several approaches to the normalization of tumor vasculature by targeting pericytes, utilization of microRNAs and extracellular tumor-associate vesicles, using immunotherapeutic drugs, and nanotechnology.

A Phase II Study Evaluating the Safety and Efficacy of Sunitinib Malate in Combination With Weekly Paclitaxel Followed by Doxorubicin and Daily Oral Cyclophosphamide Plus G-CSF as Neoadjuvant Chemotherapy for Locally Advanced or Inflammatory Breast Cancer

INTRODUCTION

Neoadjuvant chemotherapy is standard treatment for locally advanced breast cancer (LABC) or inflammatory breast cancer (IBC). We hypothesized that adding sunitinib, a tyrosine kinase inhibitor with antitumor and antiangiogenic activity, to an anthracycline and taxane regimen would improve pathologic complete response (pCR) rates to a prespecified endpoint of 45% in patients with HER2-negative LABC or IBC.

METHODS

We conducted a multicenter, phase II trial of neoadjuvant sunitinib with paclitaxel (S+T) followed by doxorubicin and cyclophosphamide plus G-CSF for patients with HER2-negative LABC or IBC. Patients received sunitinib 25 mg PO daily with paclitaxel 80 mg/m² IV weekly ×12 followed by doxorubicin 24 mg/m² IV weekly + cyclophosphamide 60 mg/m² PO daily with G-CSF support. Response was evaluated using pCR in the breast and the CPS + EG score (clinical-pathologic scoring + estrogen receptor [ER] and grade).

RESULTS

Seventy patients enrolled, and 66 were evaluable for efficacy. Eighteen patients (27%) had pCR in the breast (10 had ER⁺ disease and 8 had triple-negative disease). When defining response as pCR and/or CPS + EG score ≤2, 31 (47%) were responders. In pateints with ER positive disease, 23 (64%) were responders. The most common toxicities were cytopenias and fatigue.

CONCLUSIONS

Neoadjuvant S+T followed by AC+G-CSF was safe and tolerable in LABC and IBC. The study did not meet the prespecified endpoint for pCR; however, 47% were responders using pCR and/or CPS + EG score ≤2. ER positive patients had the highest response rate (64%). The addition of sunitinib to neoadjuvant chemotherapy may provide promising incremental benefit for patients with ER positive LABC.

Clinical impact of PD-L1 expression in triple-negative breast cancer patients with residual tumor burden after neoadjuvant chemotherapy

BACKGROUND

Studies on PD-L1 expression in breast cancer have gained importance in recent years, especially in triple-negative breast cancer (TNBC). Our aim was to analyze the differential expression of PD-L1 to explore its correlation with response to neoadjuvant chemotherapy (NACT) and patient survival.

METHODS

PD-L1 expression was evaluated immunohistochemically (Ventana SP263 clone kit) by staining tumor specimen. PD-L1 positivity was defined as membranous staining > 1%, > 5%, > 10%, and > 20% on either tumor cell (TC) and /or immune cell (IC).

RESULTS

Fifty patients with locally advanced TNBC, who had a partial response to NACT, were included in the study. PD-L1 staining was observed in TCs in 25 patients (50%) and in ICs in 23 patients (46%) when PD-L1 > 1% was considered positive. Patients with PD-L1 positivity on ICs were more likely to respond to chemotherapy as measured by "MD Anderson Cancer Center Residual Cancer Burden Index" (14/22, 63.6% vs. 10/27, 37%, p = 0.064). The 5-year disease-free survival (DFS) and disease-specific survival (DSS) rates were 46.3% and 51.4%, respectively. A high (> 20%) tumoral PD-L1 positivity was associated with a better DFS and DSS.

CONCLUSIONS

Studies in the literature mostly focused on PD-L1 expression in inflammatory cells. However, our results suggest that patients with a high PD-L1 expression on TCs were more likely to have a better outcome. Since patients with residual tumor burden who express PD-L1 on TILs were more likely to respond to NACT, an immune checkpoint inhibitor therapy in addition to NACT would be an important option for TNBC with locally advanced disease.

Ultrasound-Targeted Microbubble Destruction Enhances Inhibitory Effect of Apatinib on Angiogenesis in Triple Negative Breast Carcinoma Xenografts

Ultrasound-targeted microbubble destruction (UTMD) has been proven as an effective technique to assist drugs to cross the vascular wall and cell membrane. This study was aimed at evaluating the synergistic antiangiogenic and growth-inhibiting effects of apatinib (APA) and UTMD on the triple negative breast cancer (TNBC). The TNBC xenograft model was established in nude mice (n = 40) which were then randomly divided into the APA plus UTMD (APA-U) group, UTMD group, APA group, and model control (M) group (n = 10 per group). Corresponding treatment was done once daily for 14 consecutive days. The general condition and body weight of tumor-bearing nude mice were monitored. Routine blood test and detection of liver and kidney function were done after treatments. The tumor size and microcirculation were examined by two-dimensional ultrasonography (2DUS) and contrast-enhanced ultrasonography (CEUS), respectively. Then, the tumor tissues were harvested for the detection of vascular endothelial growth factor (VEGF) by immunohistochemistry and for CD31-PAS double staining to assess microvessel density (MVD) and heterogeneous vascular positivity rate. After treatments, the tumor growth and angiogenesis were significantly inhibited in the APA group and the APA-U group, and these effects were more obvious in the APA-U group. The tumor volume, CEUS parameters, VEGF expression, and MVD in the APA-U group were significantly lower than those in the APA group (P < 0.05), while there were no marked differences in the heterogeneous vascular positivity rate, body weight, and blood parameters between the two groups (P > 0.05). In the UTMD group, the tumor growth and angiogenesis were not significantly inhibited, and all the parameters were similar to those in the M group (P > 0.05). During the experiment, all mice survived and generally had good condition. In conclusion, APA combined with UTMD may exert synergistic antiangiogenic and growth-inhibiting effects on the TNBC and not increase the heterogeneous vasculature and the severity of APA-related systemic side effects.

Recent therapeutic trends and promising targets in triple negative breast cancer

Breast cancer accounts for 25% of all types of cancer in women, and triple negative breast cancer (TNBC) comprises around 15~20% of breast cancers. Conventional chemotherapy and radiation are the primary systemic therapeutic strategies; no other FDA-approved targeted therapies are yet available as for TNBC. TNBC is generally characterized by a poor prognosis and high rates of proliferation and metastases. Due to these aggressive features and lack of targeted therapies, numerous attempts have been made to discover viable molecular targets for TNBC. Massive cohort studies, clinical trials, and in-depth analyses have revealed diverse molecular alterations in TNBC; however, controversy exists as to whether many of these changes are beneficial or detrimental in caner progression. Here we review the complicated tumorigenic processes and discuss critical findings and therapeutic trends in TNBC with a focus on promising therapeutic approaches, the clinical trials currently underway, and potent experimental compounds under preclinical and evaluation.

Genetic Markers in Triple-Negative Breast Cancer

Triple-negative breast cancer (TNBC) accounts for 15% to 20% of breast cancer cases and is characterized by the absence of estrogen, progesterone, and human epidermal growth factor 2 receptors. Though TNBC is a highly heterogenic and aggressive disease, TNBC patients have better response to neoadjuvant therapy compared to other breast cancer subtypes. Nevertheless, patients with residual disease have a very poor prognosis, with higher probability of relapse and lower overall survival in the first years after diagnosis. TNBC has 6 subtypes with distinct molecular signatures with different prognoses and probably different responses to therapy. The precise stratification of TNBC is therefore crucial for the development of potent standardized and targeted therapies. In spite of intensive research into finding new molecular biomarkers and designing personalized therapeutic approaches, BRCA mutational status is the only clinically validated biomarker for personalized therapy in TNBC. Recent studies have reported several promising biomarkers that are currently being validated through clinical trials. The objective of this review was to summarize the clinically relevant genetic markers for TNBC that could serve as diagnostic, prognostic, or predictive or could improve personalized therapeutic strategies.

Future Developments in Neoadjuvant Therapy for Triple-Negative Breast Cancer

Breast cancer is the 2nd leading cause of cancer-related death in women in the United States. In general, advances in targeted treatment for breast cancer have improved over the last twenty years, except in the triple-negative breast cancer (TNBC) subtype. TNBC is an aggressive breast cancer subtype with limited treatment options as compared to hormone positive breast cancers. Recently, genomic profiling of TNBC shows promise in aiding clinicians to develop personalized targeted agents. Prioritizing novel molecular-based therapies in the neoadjuvant setting may help investigators understand mechanisms of resistance and ultimately improve patient outcomes in TNBC.

Combinatorial inhibition of PTPN12-regulated receptors leads to a broadly effective therapeutic strategy in triple-negative breast cancer

Triple-negative breast cancer (TNBC) is an aggressive subtype of breast cancer diagnosed in more than 200,000 women each year and is recalcitrant to targeted therapies. Although TNBCs harbor multiple hyperactive receptor tyrosine kinases (RTKs), RTK inhibitors have been largely ineffective in TNBC patients thus far. We developed a broadly effective therapeutic strategy for TNBC that is based on combined inhibition of receptors that share the negative regulator PTPN12. Previously, we and others identified the tyrosine phosphatase PTPN12 as a tumor suppressor that is frequently inactivated in TNBC. PTPN12 restrains several RTKs, suggesting that PTPN12 deficiency leads to aberrant activation of multiple RTKs and a co-dependency on these receptors. This in turn leads to the therapeutic hypothesis that PTPN12-deficient TNBCs may be responsive to combined RTK inhibition. However, the repertoire of RTKs that are restrained by PTPN12 in human cells has not been systematically explored. By methodically identifying the suite of RTK substrates (MET, PDGFRβ, EGFR, and others) inhibited by PTPN12, we rationalized a combination RTK-inhibitor therapy that induced potent tumor regression across heterogeneous models of TNBC. Orthogonal approaches revealed that PTPN12 was recruited to and inhibited these receptors after ligand stimulation, thereby serving as a feedback mechanism to limit receptor signaling. Cancer-associated mutation of PTPN12 or reduced PTPN12 protein levels diminished this feedback mechanism, leading to aberrant activity of these receptors. Restoring PTPN12 protein levels restrained signaling from RTKs, including PDGFRβ and MET, and impaired TNBC survival. In contrast with single agents, combined inhibitors targeting the PDGFRβ and MET receptors induced the apoptosis in TNBC cells in vitro and in vivo. This therapeutic strategy resulted in tumor regressions in chemo-refractory patient-derived TNBC models. Notably, response correlated with PTPN12 deficiency, suggesting that impaired receptor feedback may establish a combined addiction to these proto-oncogenic receptors. Taken together, our data provide a rationale for combining RTK inhibitors in TNBC and other malignancies that lack receptor-activating mutations.

Neoadjuvant treatments in triple-negative breast cancer patients: where we are now and where we are going

Triple-negative breast cancer (TNBC) remains the poorest-prognosis breast cancer (BC) subtype. Gene expression profiling has identified at least six different triple-negative subtypes with different biology and sensitivity to therapies. The heterogeneous nature of TN tumors may justify the difficulty in treating this BC subtype. Several targeted agents have been investigated in clinical trials without demonstrating a clear survival benefit. Therefore, systemic chemotherapy remains the cornerstone of current clinical practice. Improving the knowledge of tumor biology is mandatory for patient management. In stages II and III, neoadjuvant systemic treatment is an effective option of care. The achievement of a pathological complete response represents an optimal surrogate for survival outcome as well as a test for tumor drug sensitivity. In this review, we provide a brief description of the main predictive biomarkers for tumor response to systemic treatment. Moreover, we review the treatment strategies investigated for TNBCs in neoadjuvant settings focusing on experimental drugs such as immunotherapy and poly [ADP-ribose] polymerase inhibitors that hold promise in the treatment of this aggressive disease. Therefore, the management of TNBC represents an urgent, current, unmet need in daily clinical practice. A key recommendation is to design biology-driven clinical trials wherein TNBC patients may be treated on the basis of tumor molecular profile.

Anti-angiogenic treatment promotes triple-negative breast cancer invasion via vasculogenic mimicry

Agents that target angiogenesis have shown limited efficacy for human triple-negative breast cancer (TNBC) in clinical trials. Along with endothelium-dependent vessels, there is also vasculogenic mimicry (VM) in the microcirculation of malignant tumors. The role of VM is not completely understood regarding anti-angiogenic treatment. In this study, human TNBC MDA-MB-231 and Hs578T and non-TNBC MCF-7 and BT474 tumor-bearing mice were treated with sunitinib, an anti-angiogenic drug, using a clinically relevant schedule. The drug was administered for one week and then discontinued. Tumor growth and invasion were observed, and the microcirculation patterns were detected with PAS/endomucin staining. Moreover, hypoxia and VM-associated proteins were evaluated with Hypoxyprobe kits and immunohistochemistry, respectively. Sunitinib significantly inhibited tumor growth in the TNBC and non-TNBC tumors. However, MDA-MB-231 and Hs578T tumors regrew and were more aggressive when the treatment was stopped. The discontinuation had no significant effect on the behavior of the non-TNBC MCF-7 and BT474 tumors. The growth of endothelium-dependent vessels in the TNBC MDA-MB-231 and Hs578T tumors were blocked by sunitinib, during which the number of VM channels significantly increased and resulted in a rebound of endothelium-dependent vessels after sunitinib discontinuation. Moreover, the VM-associated proteins VE-cadherin and Twist1 upregulated in the sunitinib-treated MDA-MB-231 and Hs578T tumors. Furthermore, the clinical significance of this upregulation was validated in 174 human breast cancers. The results from human breast cancer specimens indicated that there were more VM-positive TNBC cases than those in non-TNBC cases. HIF-1α, MMP2, VE-cadherin, and Twist1 were also expressed in a higher level in human TNBC compared with non-TNBC. In aconclusion, sunitinib promoted TNBC invasion by VM. The VM status could be helpful to predict the efficacy of anti-angiogenic therapy in patients with TNBC.

Anti-angiogenic treatment in breast cancer: Facts, successes, failures and future perspectives

Angiogenesis is one of the hallmarks of cancer and a crucial requisite in the development of tumors. Interrupting this process by blocking the vascular endothelial growth factor (VEGF) with the monoclonal antibody bevacizumab has been considered a possible breakthrough in the treatment of various types of cancer, especially for advanced disease. However in breast cancer, studies have shown ambivalent results causing debate about the value of this drug. In this article, we review the evidence for anti-angiogenic treatment options for breast cancer, as well as discuss the possible factors limiting the effectiveness of anti-angiogenic agents and offer a recommendation regarding the future research on these therapies for the treatment of breast cancer.

Sunitinib as salvage treatment including potent anti-tumor activity in carcinomatous ulcers for patients with multidrug-resistant metastatic breast cancer

OBJECTIVE

To evaluate the efficacy and safety of single-agent sunitinib as salvage treatment in Chinese patients with multidrug-resistant metastatic breast cancer (MBC).

RESULTS

37 patients were enrolled with median age of 48 years. 17 had hormone receptor (HR)-positive tumors, 7 had HER2-positive tumors, and 10 had triple-negative tumors. Among 32 evaluable patients with follow-up, 6 (18.8%) achieved partial response, 14 (43.8%) achieved stable disease, and 11 (34.4%) exhibited tumor shrinkage. The response rate in 9 patients with carcinomatous ulcers was 77.8%. The median progression free survival (PFS) was 8.6 weeks. Patients with a better response had improved overall survival and PFS relative to patients with a worse response (p = 0.007, p < 0.001). Compared with HR-negative tumor, HR-positive tumor had significantly better response to sunitinib (p = 0.035). The most frequent non-hematologic adverse events were fatigue (82.8%) and hypertension (34.5%). Grade 3/4 hematologic toxicity included neutropenia (82.8%) and thrombocytopenia (79.3%). There was no correlation between the clinical response and IHC findings.

MATERIALS AND METHODS

Patients with MBC who were resistant to multiple salvage regimens (≥ 3 previous chemotherapy lines) were enrolled to receive sunitinib monotherapy. Dosage adjustment was allowed depending on adverse events. 14 patients underwent immunohistochemistry (IHC) testing for VEGF, PDGFR, EGFR and c-KIT.

CONCLUSIONS

Sunitinib salvage treatment provided modest antitumor effect to patients with refractory multidrug-resistant MBC, especially to those with troublesome carcinomatous ulcers. The treatment-related adverse events of sunitinib were manageable through dosage adjustment.

How do I treat "triple-negative" disease

OPINION STATEMENT

Over the recent years, there has been an increasing recognition that triple-negative breast cancer constitutes a separate, albeit heterogeneous, entity arising from distinct oncogenic pathways. Despite its aggressive clinical behavior, triple-negative disease responds favorably to cytotoxic chemotherapy resulting in high response rates. Nonetheless, the relapse rates are high and, in the absence of targeted therapies to significantly alter its natural history, the prognosis can be poor. Most of the trials conducted in the past that led to the formulation of the current guidelines have indiscriminately lumped triple-negative disease with receptor-positive subtypes. Therefore, there are relatively scant data regarding how standard approaches specifically apply for triple-negative disease. By virtue of its chemosensitive nature and high probability of achieving a complete pathologic response, neoadjuvant chemotherapy in early-stage/operable and locally-advanced/inoperable triple-negative disease is highly recommended. The indications for adjuvant chemotherapy are the same as in receptor-positive tumors, although endocrine therapies or agents targeting Her2 signaling have no established role in triple-negative disease. The optimal chemotherapy is not entirely clear; however, by virtue of their efficacy in breast cancer in general, anthracycline-containing regimens are the most widely used. The incorporation of taxanes in the regimen is supported by retrospective analyses. There is scant evidence to recommend any particular agent in the metastatic setting, although the combination of ixabepilone with capecitabine was shown to be active specifically in triple-negative disease. Given the uncertainty in the optimal management of triple-negative disease, the shortcomings of contemporary regimens, and the strong rationale of novel therapies, participation in clinical trials should be strongly considered at any stage of the disease.