Novel Estrogen Receptor-Targeted Agents for Breast Cancer.

OPINION STATEMENT: It has become clear that patients whose cancers have progressed post-CDK4/6 inhibitor therapy (CDK4/6i) are not deriving the same magnitude of benefit to subsequent standard endocrine therapy as historical studies would suggest. For example, anticipated duration of benefit to fulvestrant prior to CDK4/6i historically was ~ 5-6 months, and data from the VERONICA and EMERALD trials report less than 2 months. This has magnified our need for novel endocrine agents. Some have argued that patients post-CDK4/6i may just have more endocrine-resistant tumors and perhaps should just receive chemotherapy. While this may be appropriate for some, we do not currently have an assay that reliably predicts whose cancers remain endocrine sensitive and whose are endocrine resistant. ESR1 mutations can enrich for patients whose tumors are more likely to be heavily dependent on estrogen, but this is certainly not the whole answer and many patients without ESR1 mutations continue to derive benefit from subsequent endocrine agents. Most patients would strongly prefer the side effect profile of endocrine agents compared to chemotherapy, and thus, premature use of cytotoxic agents when subsequent ER targeting can control disease is not preferred. These novel ER targeting agents (PROTAC, SERD, SERCA, CERAN) hold great promise to not only outperform standard agents like fulvestrant, but also offer the promise of agents with a different side effect profile that may be more advantageous when compared to menopausal symptoms, hot flashes, arthralgias, and sexual side effects so commonly seen with AIs. We also are likely to see these novel agents move to earlier lines, whether that be 1st line in combination with CDK4/6i or even adjuvant disease.

Rise of Antibody-Drug Conjugates: The Present and Future.

Antibody-drug conjugates (ADCs) embody a simple, but elegant, vision for cancer therapy-the delivery of a potent cytotoxic agent to tumor cells with minimal damage to normal cells-so-called smart chemo. Although there were significant challenges in achieving this milestone culminating in the first Food and Drug Administration approval in 2000, subsequent advancements in technology have led to rapid drug development with regulatory approvals for ADCs targeting a variety of tumor types. The most successful application for solid tumors has been in breast cancer, with ADCs becoming the standard of care across traditional human epidermal growth factor receptor 2 (HER2)+, hormone receptor+ (HR+) and triple-negative disease subtypes. Moreover, the improved features and gains in potency with the development of ADCs have expanded the treatment-eligible population to those with low/heterogeneous expression of the target antigen on the tumor with trastuzumab deruxtecan or in the case of sacituzumab govitecan, agnostic to target expression. Despite their antibody-directed homing, these novel agents come with their share of toxicities obligating appropriate patient selection and vigilant monitoring while on treatment. As more ADCs are included in the treatment armamentarium, mechanisms of resistance need to be studied and understood for optimal sequencing. Modifying the payload to use immune-stimulating agents or combination therapies with immunotherapy and other effective targeted therapies may further extend the utility of these agents in the treatment of solid tumors.

Targeting HER2-positive breast cancer: advances and future directions.

The long-sought discovery of HER2 as an actionable and highly sensitive therapeutic target was a major breakthrough for the treatment of highly aggressive HER2-positive breast cancer, leading to approval of the first HER2-targeted drug - the monoclonal antibody trastuzumab - almost 25 years ago. Since then, progress has been swift and the impressive clinical activity across multiple trials with monoclonal antibodies, tyrosine kinase inhibitors and antibody-drug conjugates that target HER2 has spawned extensive efforts to develop newer platforms and more targeted therapies. This Review discusses the current standards of care for HER2-positive breast cancer, mechanisms of resistance to HER2-targeted therapy and new therapeutic approaches and agents, including strategies to harness the immune system.

Antibody-drug conjugates targeting TROP-2: Clinical development in metastatic breast cancer.

Antibody drug conjugates (ADCs) combine the potent cytotoxicity of chemotherapy with the antigen -specific targeted approach of antibodies into one single molecule. Trophoblast cell surface antigen 2 (TROP-2) is a transmembrane glycoprotein involved in calcium signal transduction and is expressed in multiple tumor types. TROP-2 expression is higher in HER2-negative breast tumors (HR+/HR-) and is associated with worse survival. Sacituzumab govitecan (SG) is a first-in-class TROP-2-directed ADC with an anti-TROP-2 antibody conjugated to SN-38, a topoisomerase inhibitor via a hydrolysable linker. This hydrolysable linker permits intracellular and extracellular release of the membrane permeable payload enabling the "bystander effect" contributing to the efficacy of this agent. There was significant improvement in progression free survival (PFS) and overall survival (OS) with SG versus chemotherapy in pretreated metastatic triple negative breast cancer (TNBC), resulting in regulatory approval. Common adverse events (AE) reported were neutropenia and diarrhea. SG also demonstrated clinical activity versus chemotherapy in a phase III trial of HR+/HER2-metastatic breast cancer (MBC) and is under evaluation in first-line metastatic and early stage TNBC as well. Datopotamab deruxtecan (Dato-DXd) is a TROP-2 ADC that differs from SG in that it has a cleavable tetrapeptide linker and a more potent topoisomerase inhibitor payload. This construct is highly stable in circulation with a longer half-life than SG, and undergoes cleavage in presence of intracellular lysosomal proteases. Dato-DXd demonstrated preliminary efficacy in unselected metastatic TNBC, with common AEs of low-grade nausea and stomatitis. Dato-DXd is being investigated in phase III studies in metastatic TNBC and HR+/HER2- MBC. These novel TROP-2 ADCs have the potential to deliver enhanced efficacy with reduced toxicity in MBC and possibly in early stage breast cancer (EBC).

A Phase II Study Evaluating Orteronel, an Inhibitor of Androgen Biosynthesis, in Patients With Androgen Receptor (AR)-Expressing Metastatic Breast Cancer (MBC).

BACKGROUND: AR is a targetable pathway with AR modulation inhibiting estrogen- and androgen-mediated cell proliferation. Orteronel is an oral, selective, nonsteroidal inhibitor of 17, 20-lyase, a key enzyme in androgen biosynthesis. This study evaluated single-agent orteronel in AR+ metastatic breast cancer (MBC). METHODS: Male/female patients with AR+ MBC were grouped in Cohort 1: AR+ TNBC with l-3 prior chemotherapy regimens or Cohort 2: AR+ HR+ (estrogen [ER+]/ progesterone receptor [PR+] positive) HER2+/- with 1 to 3 prior hormonal and at least 1 prior chemotherapy regimen. Patients with HER2+ MBC must have received at least 2 lines of HER2-targeted therapy. Orteronel was administered at 300 mg BID; response rate was the primary endpoint. RESULTS: Seventy patients were enrolled (Cohort 1, n = 26 and Cohort 2, n = 44). Median treatment duration was 7.1 weeks. Seven patients were on treatment for ≥6 months. One of the 21 evaluated patients in Cohort 1 (4.8%) had an objective response. In Cohort 2, none of the first 23 patients to be evaluated had a response and accrual was stopped. Median progression-free and overall survival were 1.8 and 8.3 months, respectively. Toxicities were predominantly Grade 1 or 2 nausea/vomiting (36%) and fatigue (31%). Grade 3 or 4 events in ≥5% of patients included increased amylase/lipase (10%) and hypertension (6%). CONCLUSIONS: Orteronel demonstrated limited clinical activity in heavily pre-treated AR+ MBC. Further development of orteronel in MBC is not recommended. Further efforts to validate the AR as a therapeutic target should focus on identifying new markers predictive of sensitivity to AR-targeted agents.

Targeting HER2 heterogeneity in breast cancer.

The identification of Human epidermal growth factor receptor 2 (HER2) as a target in breast cancer and the subsequent development of HER2-targeted therapies has revolutionized the treatment of patients with HER2-positive breast cancer. However, there is an increasing awareness of how frequently tumors have low or heterogeneous expression of HER2. It is now recognized that this impacts the degree of benefit from HER2-targeted therapies. With the advent of novel and more potent antibody drug conjugates, targeting HER2 in traditional HER2-negative tumors with "HER2-low" expression is becoming possible. It is essential to refine the nomenclature around HER2 expression to enable clinicians to optimize treatment for patients across the HER2 expression spectrum in breast cancer. HER2 heterogeneity can be detected by conventional IHC, gene expression profiling or other methods and numerous studies have documented the correlation between the presence of HER2 heterogeneity and shorter disease-free survival (DFS) and overall survival (OS). Validation of techniques to identify HER2 heterogeneity in the clinic and concurrent development of agents to effectively treat tumors with non-uniform HER2 expression is needed.

Next-Generation Sequencing of Patients With Breast Cancer in Community Oncology Clinics.

PURPOSE: Molecular biomarkers informing disease diagnosis, prognosis, and treatment decisions in patients with breast cancer are being uncovered by next-generation sequencing (NGS) technologies. In this study, we survey how NGS is used for patients with breast cancer in real-world settings with a focus on physician behaviors and sequencing results. METHODS: We conducted a retrospective analysis of patients with breast cancer who received NGS testing from commercial vendors as part of standard of care from 2014 to 2019. A total of 2,635 NGS reports from 2,316 unique breast cancer patients were assessed. Hormone receptor and human epidermal growth factor receptor 2 statuses were abstracted from patient medical records. Comparative gene amplification and mutation frequencies were analyzed using Pearson's correlation and Lin's concordance statistics. RESULTS: The number of physicians ordering NGS tests for patients with breast cancer increased more than six-fold from 2014 to 2019. Tissue- and plasma-based tests were ordered roughly equally by 2019, with plasma-based testing ordered most frequently in hormone receptor-positive subtypes. Patients with triple-negative breast cancer were most likely to receive NGS testing. Gene amplifications including ERBB2 were detected less frequently in our real-world data set as compared to previous genomic landscape studies, whereas the opposite was true for gene mutations including ESR1. Pathogenic mutations in the PI3K pathway (38.6%) and DNA damage repair pathway (11.0%) were frequently reported. Alterations were also reported across other cellular pathways. CONCLUSION: Overall, we found that an increasing number of physicians in community settings are adopting NGS in the care of patients with breast cancer. Discrepancies between our real-world NGS data and previous genomic landscape studies are likely owed to the prevalence of plasma-based testing in community oncology clinics, as the reference data were from tissue-based NGS alone.

Phase II trial of eribulin in patients who do not achieve pathologic complete response (pCR) following neoadjuvant chemotherapy.

PURPOSE: Women with residual invasive breast cancer at the primary site or axillary lymph nodes following neoadjuvant chemotherapy have a high risk of recurrence. Eribulin improves survival in patients with metastatic breast cancer who progress after anthracycline and taxane therapy. This phase 2 trial assessed the efficacy of postoperative eribulin in breast cancer patients who did not achieve a pCR following standard neoadjuvant chemotherapy. METHODS: Women with localized breast cancer who had residual invasive cancer following ≥ 4 cycles of standard anthracycline and/or taxane-containing neoadjuvant chemotherapy received adjuvant eribulin treatment. HER2-positive patients also received trastuzumab for 1 year. Adjuvant hormonal therapy and locoregional radiotherapy were administered as per institutional guidelines. Primary endpoint was the 2-year DFS rate. Three patient cohorts were analyzed: TNBC (Cohort A), HR+/HER2- (Cohort B), and HER2+ (Cohort C). RESULTS: One hundred twenty-six patients (Cohort A-53, Cohort B-42, and Cohort C-31) were enrolled. Neoadjuvant chemotherapy included a taxane and an anthracycline in 70%. Eribulin was well tolerated; 84% of patients received the planned 6 cycles. After a median follow-up of 28 months, the 24-month DFS rates were 56% (95% CI 42, 69), 83% (95% CI 67, 91), and 73% (95% CI 53, 86) for Cohorts A, B, and C, respectively. The most common grade 3/4 treatment-related adverse events were neutropenia (26%), leukopenia (13%), and neuropathy (7%). CONCLUSION: Administration of adjuvant eribulin after neoadjuvant chemotherapy was feasible and well tolerated. The 24-month DFS rate did not reach the study target levels in any of the cohorts and was similar to DFS previously described in these cohorts following neoadjuvant chemotherapy alone.

A Phase II Open Label Study of Everolimus in Combination With Endocrine Therapy in Resistant Hormone Receptor-Positive HER2-Negative Advanced Breast Cancer.

BACKGROUND: Therapies targeting estrogen receptor signaling are standard for patients with hormone receptor (HR)-positive (HR+) metastatic breast cancer (MBC). Dysregulation of the phosphoinositol 3-kinase (PI3K)/protein kinase B (AKT)/mammalian target of rapamycin (mTOR) pathway is associated with treatment resistance. Addition of the mTOR inhibitor, everolimus, to exemestane doubled progression-free survival (PFS) in HR+/HER2- MBC patients whose disease had previously progressed during endocrine therapy. In this phase II study, we used everolimus in addition to the most recent endocrine therapy during which a patient's disease progressed, in an attempt to restore and extend the benefit of the antiestrogen therapy in patients with HR+/HER2- MBC. PATIENTS AND METHODS: Patients with HR+ MBC who progressed on antiestrogen therapy received everolimus (10 mg orally daily) in combination with the antiestrogen therapy most recently administered. Treatment was administered in 4-week cycles and continued until disease progression or unacceptable toxicity. Blood and archival tumor specimens were collected for VeriStrat (Biodesix, Inc) and Foundation One (Foundation Medicine) assays, respectively. Accrual of 42 evaluable patients allowed detection of improvement in median PFS from 2.8 months (expected with hormonal treatment alone) to 5 months (power 80%, α = 5%). RESULTS: Forty-seven patients were enrolled and treated. After a median follow-up of 22.2 months, median PFS was 6.6 months. Secondary efficacy end points included: overall response rate, 6%; clinical benefit rate, 40%; and median overall survival, 21.1 months. No unexpected toxicity was observed. Efficacy could not be correlated with PI3K/AKT/mTOR alterations or VeriStrat (Biodesix, Inc) prognostic signatures. CONCLUSION: After progression during antiestrogen therapy, the addition of everolimus, without changing the hormonal therapy, resulted in a median PFS of 6.6 months, suggesting efficacy in patients with HR+/HER2- MBC.

Practical Treatment Strategies and Future Directions After Progression While Receiving CDK4/6 Inhibition and Endocrine Therapy in Advanced HR+/HER2- Breast Cancer.

Cyclin-dependent kinase 4/6 inhibitors (CDK4/6i) in combination with backbone endocrine therapy have markedly improved progression-free survival and overall survival over endocrine therapy alone in advanced hormone receptor-positive, HER2-negative (HR+/HER2-) breast cancer and are the standard of care in the first- or second-line setting. There are few data to drive decision making for subsequent treatment strategies after inevitable disease progression after CDK4/6i. Information about the genomic landscape of CDK4/6i-resistant disease is emerging. Resistance mechanisms appear to be varied, but mutations in PIK3CA and ESR1, which can be acquired while receiving treatment, are frequent. Activating PIK3CA mutations are present in up to 35% of patients and are now the most actionable genomic alteration in HR+/HER2- advanced breast cancer with the recent approval of alpelisib and fulvestrant. Everolimus-based combinations and chemotherapy appear to have continued efficacy after progression while receiving CDK4/6i, although historical data on benefit include CDK4/6i-naive patients. Use of selective estrogen down-regulators over aromatase inhibitors is best once the patient has an acquired ESR1 mutation. Tumor biopsy with genomic sequencing and repeat biomarker analysis in patients with CDK4/6i- and endocrine-resistant disease will be integral to guide subsequent treatment strategies and to inform clinical trial eligibility. Promising novel therapeutics in CDK4/6i-resistant disease including oral selective estrogen down-regulators, fibroblast growth factor receptor antagonists, and immunotherapy will be discussed.

Phase I/II study of bevacizumab with BKM120, an oral PI3K inhibitor, in patients with refractory solid tumors (phase I) and relapsed/refractory glioblastoma (phase II).

BACKGROUND: Current bevacizumab-based regimens have failed to improve survival in patients with recurrent glioblastoma. To improve treatment efficacy, we evaluated bevacizumab + BKM120, an oral pan-class I PI3K inhibitor, in this patient population. METHODS: A brief phase I study established the optimal BKM120 dose to administer with standard-dose bevacizumab. BKM120 60 mg PO daily + bevacizumab 10 mg/kg IV every 2 weeks in 28-day cycles was then administered to patients with relapsed/refractory glioblastoma in the phase II portion. RESULTS: Eighty-eight patients enrolled (phase I, 12; phase II, 76). In phase I, BKM120 80 mg PO daily produced dose limiting toxicity in 3 of 6 patients; a BKM120 dose of 60 mg PO daily was established as the maximum tolerated dose. In phase II, the median progression-free survival (PFS) was 4.0 months (95% CI 3.4, 5.4), PFS at 6 months was 36.5%, and the overall response rate was 26%. Forty-two patients (57%) experienced one or more serious treatment related toxicities. The most common CNS toxicities included mood alteration (17%) and confusion (12%); however, these were often difficult to classify as treatment- versus tumor-related. CONCLUSIONS: The efficacy seen in this study is similar to the efficacy previously reported with single-agent bevacizumab. This regimen was poorly tolerated, despite the low daily dose of BKM120. Further development of this combination for the treatment of glioblastoma is not recommended.

A Randomized Phase II Study of Eribulin/Cyclophosphamide or Docetaxel/Cyclophosphamide as Neoadjuvant Therapy in Operable HER2-negative Breast Cancer.

BACKGROUND: Eribulin mesylate is a non-taxane microtubule inhibitor effective in the treatment of metastatic breast cancer refractory to anthracyclines and taxanes. In preclinical studies, additional mechanisms of eribulin included reversal of epithelial mesenchymal transition and tumor vascular remodeling. The present study compared the safety and efficacy of eribulin plus cyclophosphamide (ErC) to docetaxel plus cyclophosphamide (TC) as neoadjuvant therapy for operable HER2- breast cancer. PATIENTS AND METHODS: Women with invasive HER2- breast adenocarcinoma with no distant metastases were eligible. After a 10-patient safety lead-in, the patients were randomized 2:1 to receive either ErC (eribulin 1.4 mg/m2 on days 1 and 8 plus cyclophosphamide 600 mg/m2 on day 1) or TC (docetaxel 75 mg/m2 plus cyclophosphamide 600 mg/m2 on day 1) administered every 21 days for 6 cycles, followed by surgery. The pathologic complete response (pCR) rate was the primary endpoint. Tumor samples collected at baseline and at surgery were assayed for select epithelial mesenchymal transition and vascular density markers: E-cadherin, vimentin, and CD31 expression. RESULTS: A total of 76 patients were enrolled. Of the 76 patients, 10 received ErC in the lead-in phase and 66 were randomized to ErC (n = 44) or TC (n = 22). The pCR rates with ErC and TC were 13% and 9%, respectively. Both regimens produced frequent neutropenia and peripheral neuropathy. Both regimens increased vascular density as measured by CD31 staining. CONCLUSION: The neoadjuvant regimens of ErC and TC resulted in relatively low pCR rates in this patient population. No unexpected toxicities were observed. Our results also provided no suggestion that ErC is a neoadjuvant treatment with greater efficacy than that of standard regimens.

Cabazitaxel Plus Lapatinib as Therapy for HER2+ Metastatic Breast Cancer With Intracranial Metastases: Results of a Dose-finding Study.

BACKGROUND: Lapatinib is an oral small molecule tyrosine kinase epidermal growth factor receptor-1/HER2 inhibitor that crosses the blood-brain barrier and is active against central nervous system (CNS) metastases. Cabazitaxel is a taxoid that is effective against taxane-resistant metastatic breast cancer (MBC) and has distinguished itself by its ability to cross the blood-brain barrier. The present phase II study (ClinicalTrials.gov identifier, NCT01934894) evaluated the combination of these agents to treat HER2+ MBC patients with CNS metastases. MATERIALS AND METHODS: Patients with HER2+ MBC and ≥ 1 untreated or progressive, measurable CNS metastasis were eligible. Using a 3+3 dose escalation design, patients were treated with escalating doses of intravenous cabazitaxel every 21 days and oral lapatinib daily in 21-day treatment cycles. Intracranial disease restaging was performed every 2 cycles for the first 8 cycles and then every 3 cycles until progression or unacceptable toxicity. RESULTS: Eleven patients were treated at 2 dose levels. Six patients were treated at dose level 1 (intravenous cabazitaxel 20 mg/m2 plus oral lapatinib 1000 mg daily), and five were treated at dose level 2 (intravenous cabazitaxel 25 mg/m2 plus oral lapatinib 1000 mg daily). The most common treatment-related adverse events were myelosuppression, diarrhea, fatigue, and skin toxicity. A total of 5 dose-limiting toxicity events occurred. No intra- or extracranial objective responses were observed. CONCLUSION: The combination of cabazitaxel plus lapatinib was not feasible because of toxicity and because no objective CNS activity was seen in the 5 evaluable patients. The role of cabazitaxel to treat breast cancer patients with CNS metastases remains undefined.

A phase II trial of bevacizumab and everolimus as treatment for patients with refractory, progressive intracranial meningioma.

Meningiomas that progress after standard therapies are challenging with limited effective chemotherapy options. This phase II trial evaluated the efficacy of everolimus plus bevacizumab in patients with recurrent, progressive meningioma after treatment with surgical resection and local radiotherapy when appropriate. Patients with recurrent meningioma (WHO grade I, II, or III) following standard treatments with surgical resection and radiotherapy received bevacizumab (10 mg/kg IV days 1 and 15) and everolimus (10 mg PO daily) each 28 day cycle. Evaluation of response occurred every 2 cycles. The primary endpoint was progression-free survival (PFS). Secondary endpoints included response rate, overall survival and safety. Seventeen patients with a median age of 59 years (29-84) received study treatment. WHO grades at study entry included: I, 5 (29 %); II, 7 (41 %); III, 4 (24 %); unknown, 1 (6 %). Patients received a median of 8 cycles (1-37); all patients are off study treatment. A best response of SD was observed in 15 patients (88 %), and 6 patients had SD for >12 months. Overall median PFS was 22 months (95 % CI 4.5-26.8) and was greater for patients with WHO grade II and III compared to grade I tumors (22.0 months vs 17.5 months). Four patients discontinued treatment due to toxicity (proteinuria, 2; colitis, 1, thrombocytopenia, 1). However, other grade 3 toxicity was uncommon, and no patient had grade 4 toxicity. The combination of everolimus and bevacizumab was well-tolerated, and produced stable disease in 88 % of patients; the median duration of disease stabilization of 10 months (2-29). The median PFS from this prospective trial was similar to previous retrospective reports of bevacizumab in the treatment of recurrent meningioma.

A phase II trial of ixabepilone and cyclophosphamide as neoadjuvant therapy for patients with HER2-negative breast cancer: correlation of pathologic complete response with the 21-gene recurrence score.

Ixabepilone and the taxanes have similar activity in the first-line treatment of metastatic breast cancer, and ixabepilone is sometimes effective in taxane-refractory patients. We conducted a phase 2 trial to evaluate ixabepilone in combination with cyclophosphamide as neoadjuvant treatment for patients with locally advanced HER2-negative breast cancer. Response to neoadjuvant treatment was correlated with the baseline 21-gene Recurrence Score® (Oncotype DX; Genomic Health Inc, Redwood City, CA). Eligible women with HER2-negative locally advanced breast cancer received ixabepilone 40 mg/m(2) plus cyclophosphamide 600 mg/m(2) on day 1 of each 21-day cycle. Following 6 cycles, patients underwent definitive surgery. Primary endpoint was rate of pathologic complete response (pCR). Breast biopsy tumor samples were obtained at pretreatment and at surgery in patients with residual disease. Tumor specimens were analyzed using the 21-gene assay. One hundred sixty-eight patients (median age 52 years; 45 % triple-negative) were enrolled; 161 (96 %) underwent definitive surgery following neoadjuvant ixabepilone/cyclophosphamide. Overall, 27 patients (17 %) achieved pCR, including 19 of 73 (26 %) triple-negative patients. The most frequently occurring grade 3/4 toxicity was neutropenia (98 patients; 58 %). Recurrence Scores were highly correlated with achievement of pCR (0/36 with low or intermediate Recurrence Scores vs. 19/72 with high Recurrence Scores; p = 0.002). There was high concordance between baseline and post-treatment Recurrence Scores in the 72 patients with paired samples. The combination of ixabepilone and cyclophosphamide yielded a pCR rate of 17 %, similar to other neoadjuvant chemotherapy regimens. Pathologic complete responses occurred only in patients with high-risk baseline Recurrence Scores.

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

The purpose of the study is to evaluate the feasibility and efficacy of adding sunitinib to paclitaxel/carboplatin in the neoadjuvant therapy of patients with triple-negative breast cancer (TNBC). Patients had histologically proven, previously untreated, triple-negative adenocarcinoma, with disease limited to the breast and axilla (clinical T1-T3, N0-N2, M0; T1N1M0 excluded). Following determination of the maximum tolerated doses in the phase I portion, patients in the phase II study received paclitaxel 70 mg/m(2) IV days 1, 8, and 15; carboplatin AUC 5.0 IV day 1; sunitinib 25 mg orally daily; treatment was administered for six 28-day cycles followed by definitive surgery. Sunitinib was resumed postoperatively to complete a 52-week course. Pathologic complete response (pCR) rate was the primary endpoint. Fifty-four patients enrolled; 41 received treatment in the phase II study. Sixteen patients (39 %) were able to complete six cycles of neoadjuvant therapy; 18 additional patients had surgery after completing 2-5 cycles of treatment. The pCR rate in these 34 evaluable patients was 35 %. The toxicity of the regimen was considerable, with myelosuppression resulting in numerous dose reductions and/or omissions of paclitaxel and carboplatin. Eleven patients (27 %) discontinued sunitinib during neoadjuvant therapy, and six patients (14 %) completed 52 weeks of single-agent sunitinib. In the neoadjuvant treatment of patients with TNBC, the combination of paclitaxel, carboplatin, and sunitinib was difficult to administer, and produced a pCR rate comparable to other less toxic regimens. This combination is not recommended for further evaluation. At present, sunitinib has no defined role in the treatment of breast cancer.

Updates in the treatment of basal/triple-negative breast cancer.

PURPOSE OF REVIEW: Triple-negative breast cancer (TNBC) is clinically characterized by the lack of expression of the estrogen receptor/progesterone receptor and the human epidermal growth factor receptor 2. It is highly heterogeneous and exhibits considerable overlap with basal-like and BRCA-related breast cancers. Constituting 15-20% of breast cancers, TNBC exhibits an aggressive phenotype with a poor prognosis. This review summarizes recent progress and studies in TNBC and discusses some of the ongoing clinical trials and emerging therapies for the treatment of TNBC. RECENT FINDINGS: Conventional cytotoxic chemotherapy and DNA damaging agents continue to be the mainstay for treatment of this disease. The use of targeted agents such as bevacizumab, epidermal growth factor receptor and polyadenosine diphosphate-ribose polymerase inhibitors have led to conflicting results. However, recent research has prompted evaluation of additional drugs targeting multiple signaling pathways and epigenetic modifications for the treatment of this disease. SUMMARY: TNBC remains a challenging disease to treat with recent trials having demonstrated only modest improvements in outcomes. Increased understanding of the heterogeneity of this complex subtype may help tailor therapies to specific patient subgroups.

Phase II study of neoadjuvant weekly nab-paclitaxel and carboplatin, with bevacizumab and trastuzumab, as treatment for women with locally advanced HER2+ breast cancer.

PURPOSE: Neoadjuvant treatment with chemotherapy plus trastuzumab is standard care for women with locally advanced, HER2-positive (HER2(+)) breast cancer. HER2 has been shown to stimulate angiogenesis through vascular endothelial growth factor upregulation. We investigated the feasibility and efficacy of bevacizumab in combination with trastuzumab, nab-paclitaxel, and carboplatin as neoadjuvant therapy for women with locally advanced HER2(+) breast cancer. PATIENTS AND METHODS: Twenty-eight women with locally advanced HER2(+) breast cancer received nab-paclitaxel (100 mg/m(2) intravenously [I.V.] days 1,8, and 15) and carboplatin (AUC = 6 I.V. day 1) every 28 days × 6 cycles. Concurrent with chemotherapy, trastuzumab (4 mg/kg loading dose, then 2 mg/kg) and bevacizumab (5 mg/kg I.V.) were administered weekly × 23 weeks. Patients then underwent mastectomy or breast-conserving surgery; pathologic responses were assessed. After surgery, trastuzumab 6 mg/kg and bevacizumab 15 mg/kg were administered every 3 weeks (54 weeks total); locoregional radiotherapy and/or antiestrogen therapy was administered per standard guidelines. RESULTS: Twenty-six patients (90%) completed neoadjuvant therapy, with objective responses in 86%. Pathologic complete response (pCR) was confirmed in 14 of the 26 patients (54%) who had surgery. However, bevacizumab-related complications were common postoperatively and during adjuvant trastuzumab/bevacizumab therapy. Ten patients had wound-healing delays or infections (6 patients discontinued therapy); 4 patients had left ventricular ejection fraction (LVEF) decreases (1 patient discontinued therapy). Other severe treatment-related toxicity was uncommon. Only 9 patients (31%) completed all protocol therapy. CONCLUSIONS: Neoadjuvant therapy with nab-paclitaxel, carboplatin, trastuzumab, and bevacizumab was feasible in most patients, producing a pCR rate comparable to that in chemotherapy/trastuzumab combinations. In contrast, prolonged bevacizumab/trastuzumab therapy after surgical treatment was not well tolerated, primarily due to bevacizumab-related toxicity. The role of bevacizumab in neoadjuvant therapy remains undefined.