Targeted therapy with the humanized monoclonal antibody trastuzumab has become a mainstay for human epidermal growth factor receptor 2 (HER2) -positive breast cancer (BC). The mechanisms of action of ...trastuzumab have not been fully elucidated, and data available to date are reviewed here. The impact of the mechanisms of action on clinical benefit also is discussed.
An extensive literature review of trastuzumab and proposed mechanisms of action was performed.
At least five potential extracellular and intracellular antitumor mechanisms of trastuzumab have been identified in the preclinical setting. These include activation of antibody-dependent cellular cytotoxicity, inhibition of extracellular domain cleavage, abrogation of intracellular signaling, reduction of angiogenesis, and decreased DNA repair. These effects lead to tumor cell stasis and/or death. Clinical benefit from trastuzumab-based therapy in both early and advanced BC has been demonstrated. The benefit of trastuzumab use beyond progression has also been shown, which indicates the need for continuous suppression of the HER2 pathway. Targeting both HER2, with various approaches, and other pathways may enhance the clinical benefit observed with trastuzumab and overcome potential resistance. Novel combinations include pertuzumab (a HER2 dimerization inhibitor), lapatinib (a HER1/HER2 tyrosine kinase inhibitor), bevacizumab (an antiangiogenic agent), tanespimycin (a heat shock protein inhibitor), antiestrogen therapies, and an antibody-drug conjugate (trastuzumab-DM1).
Trastuzumab is the foundation of care for patients with HER2-positive BC. Emerging data from studies of other targeted agents may provide alternative treatment combinations to maximize the clinical benefit from trastuzumab and prevent or delay resistance. The continued development of trastuzumab highlights promising treatment approaches for the future.
Phase III EGF104900 data demonstrated that lapatinib plus trastuzumab significantly improved progression-free survival (PFS) and clinical benefit rate versus lapatinib monotherapy, offering a ...chemotherapy-free option for patients with heavily pretreated human epidermal growth factor receptor 2 (HER2) -positive metastatic breast cancer (MBC). Final planned overall survival (OS) analysis from EGF104900 is reported here.
Patients with HER2-positive MBC whose disease progressed during prior trastuzumab-based therapies were randomly assigned to receive lapatinib monotherapy or lapatinib in combination with trastuzumab. OS and updated PFS data are presented using Kaplan-Meier curves and log-rank tests stratified for hormone receptor and visceral disease status. Subgroup analyses were conducted to identify characteristics of patients deriving the greatest clinical benefit.
In this updated final analysis of all patients randomly assigned with strata (n = 291), lapatinib plus trastuzumab continued to show superiority to lapatinib monotherapy in PFS (hazard ratio HR, 0.74; 95% CI, 0.58 to 0.94; P = .011) and offered significant OS benefit (HR, 0.74; 95% CI, 0.57 to 0.97; P = .026). Improvements in absolute OS rates were 10% at 6 months and 15% at 12 months in the combination arm compared with the monotherapy arm. Multiple baseline factors, including Eastern Cooperative Oncology Group performance status of 0, nonvisceral disease, < three metastatic sites, and less time from initial diagnosis until random assignment, were associated with improved OS. Incidence of adverse events was consistent with previously reported rates.
These data demonstrated a significant 4.5-month median OS advantage with the lapatinib and trastuzumab combination and support dual HER2 blockade in patients with heavily pretreated HER2-positive MBC.
Preclinical studies in ErbB2-positive cell lines demonstrated a synergistic interaction between lapatinib and trastuzumab, suggesting that dual blockade is more effective than a single agent alone. ...EGF104900 compared the activity of lapatinib alone or in combination with trastuzumab in patients with ErbB2-positive, trastuzumab-refractory metastatic breast cancer (MBC).
Patients with ErbB2-positive MBC who experienced progression on prior trastuzumab-containing regimens were randomly assigned to receive either lapatinib alone or in combination with trastuzumab. The primary end point was progression-free survival (PFS). Secondary efficacy end points included overall response rate (ORR), clinical benefit rate (CBR; complete response, partial response, and stable disease for >/= 24 weeks), and overall survival (OS).
In the intent-to-treat population (N = 296) who received a median of three prior trastuzumab-containing regimens, the combination of lapatinib with trastuzumab was superior to lapatinib alone for PFS (hazard ratio HR = 0.73; 95% CI, 0.57 to 0.93; P = .008) and CBR (24.7% in the combination arm v 12.4% in the monotherapy arm; P = .01). A trend for improved OS in the combination arm was observed (HR = 0.75; 95% CI, 0.53 to 1.07; P = .106). There was no difference in ORR (10.3% in the combination arm v 6.9% in the monotherapy arm; P = .46). The most frequent adverse events were diarrhea, rash, nausea, and fatigue; diarrhea was higher in the combination arm (P = .03). The incidence of symptomatic and asymptomatic cardiac events was low (combination therapy = 2% and 3.4%; monotherapy = 0.7% and 1.4%, respectively).
Despite disease progression on prior trastuzumab-based therapy, lapatinib in combination with trastuzumab significantly improved PFS and CBR versus lapatinib alone, thus offering a chemotherapy-free option with an acceptable safety profile to patients with ErbB2-positive MBC.
Cyclin-dependent kinase (CDK) 4/6 inhibitor-based therapies have shown great promise in improving clinical outcomes for patients with hormone receptor-positive (HR+), human epidermal growth factor ...receptor 2-negative (HER2-) advanced breast cancer.
1. Discuss the mode of action of the three CDK4/6 inhibitors in late clinical development: palbociclib (PD-0332991; Pfizer), ribociclib (LEE011; Novartis), and abemaciclib (LY2835219; Lilly). 2. Describe the efficacy and safety data relating to their use in HR+, HER2- advanced breast cancer. 3. Discuss the key side effects associated with CDK4/6 inhibitors along with considerations for adverse event management and patient monitoring.
Relevant information and data were assimilated from manuscripts, congress publications, and online sources.
CDK4/6 inhibitors have demonstrated improved progression-free survival in combination with endocrine therapy compared with endocrine therapy alone. The side-effect profile of each agent is described, along with implications for patient monitoring, and considerations for patient care providers and pharmacists.
Addition of a CDK4/6 inhibitor to endocrine therapy increases efficacy and delays disease progression. Insight into the unique side-effect profiles of this class of agents and effective patient monitoring will facilitate the successful use of CDK4/6 inhibitor-based therapies in the clinic.
Leptomeningeal disease has become increasingly prevalent as novel therapeutic interventions extend the survival of cancer patients. Although a majority of leptomeningeal spread occurs secondary to ...breast cancer, lung cancer, and melanoma, a wide variety of malignancies have been reported as primary sources. Symptoms on presentation are equally diverse, often involving a combination of neurological deficits with the possibility of obstructive hydrocephalus. Diagnosis is definitively made via cerebrospinal fluid cytology for malignant cells, but neuro-imaging with high quality T1-weighted magnetic resonance imaging can aid diagnosis and localization. While leptomeningeal disease is still a terminal, late-stage complication, a variety of treatment modalities, such as intrathecal chemotherapeutics and radiation therapy, have improved median survival from 4-6 weeks to 3-6 months. Positive prognosticative factors for survival include younger age, high performance scores, and controlled systemic disease. In looking to the future, diagnostics that improve early detection and chemotherapeutics tailored to the primary malignancy will likely be the most significant advances in improving survival.
Evidence-based treatments for metastatic, human epidermal growth factor receptor 2 (HER2)-positive breast cancer to the CNS are limited. We previously reported modest activity of neratinib ...monotherapy for HER2-positive breast cancer brain metastases. Here we report the results from additional study cohorts.
Patients with measurable, progressive, HER2-positive brain metastases (92% after receiving CNS surgery and/or radiotherapy) received neratinib 240 mg orally once per day plus capecitabine 750 mg/m
twice per day for 14 days, then 7 days off. Lapatinib-naïve (cohort 3A) and lapatinib-treated (cohort 3B) patients were enrolled. If nine or more of 35 (cohort 3A) or three or more of 25 (cohort 3B) had CNS objective response rates (ORR), the drug combination would be deemed promising. The primary end point was composite CNS ORR in each cohort separately, requiring a reduction of 50% or more in the sum of target CNS lesion volumes without progression of nontarget lesions, new lesions, escalating steroids, progressive neurologic signs or symptoms, or non-CNS progression.
Forty-nine patients enrolled in cohorts 3A (n = 37) and 3B (n = 12; cohort closed for slow accrual). In cohort 3A, the composite CNS ORR = 49% (95% CI, 32% to 66%), and the CNS ORR in cohort 3B = 33% (95% CI, 10% to 65%). Median progression-free survival was 5.5 and 3.1 months in cohorts 3A and 3B, respectively; median survival was 13.3 and 15.1 months. Diarrhea was the most common grade 3 toxicity (29% in cohorts 3A and 3B).
Neratinib plus capecitabine is active against refractory, HER2-positive breast cancer brain metastases, adding additional evidence that the efficacy of HER2-directed therapy in the brain is enhanced by chemotherapy. For optimal tolerance, efforts to minimize diarrhea are warranted.
Based on promising preclinical data, we conducted a single-arm phase II trial to assess the clinical benefit rate (CBR) of neratinib, defined as complete/partial response (CR/PR) or stable disease ...(SD) ≥24 weeks, in
nonamplified metastatic breast cancer (MBC). Secondary endpoints included progression-free survival (PFS), toxicity, and circulating tumor DNA (ctDNA)
detection.
Tumor tissue positive for
was required for eligibility. Neratinib was administered 240 mg daily with prophylactic loperamide. ctDNA sequencing was performed retrospectively for 54 patients (14 positive and 40 negative for tumor
).
Nine of 381 tumors (2.4%) sequenced centrally harbored
(lobular 7.8% vs. ductal 1.6%;
= 0.026). Thirteen additional
cases were identified locally. Twenty-one of these 22
cases were estrogen receptor positive. Sixteen patients median age 58 (31-74) years and three (2-10) prior metastatic regimens received neratinib. The CBR was 31% 90% confidence interval (CI), 13%-55%, including one CR, one PR, and three SD ≥24 weeks. Median PFS was 16 (90% CI, 8-31) weeks. Diarrhea (grade 2, 44%; grade 3, 25%) was the most common adverse event. Baseline ctDNA sequencing identified the same
in 11 of 14 tumor-positive cases (sensitivity, 79%; 90% CI, 53%-94%) and correctly assigned 32 of 32 informative negative cases (specificity, 100%; 90% CI, 91%-100%). In addition, ctDNA
variant allele frequency decreased in nine of 11 paired samples at week 4, followed by an increase upon progression.
Neratinib is active in
, nonamplified MBC. ctDNA sequencing offers a noninvasive strategy to identify patients with
cancers for clinical trial participation.
.
Breast cancer arising in young women is correlated with inferior survival and higher incidence of negative clinicopathologic features. The biology driving this aggressive disease has yet to be ...defined.
Clinically annotated, microarray data from 784 early-stage breast cancers were identified, and prospectively defined, age-specific cohorts (young: </= 45 years, n = 200; older: >/= 65 years, n = 211) were compared by prognosis, clinicopathologic variables, mRNA expression values, single-gene analysis, and gene set enrichment analysis (GSEA). Univariate and multivariate analyses were performed.
Using clinicopathologic variables, young women illustrated lower estrogen receptor (ER) positivity (immunohistochemistry IHC, P = .027), larger tumors (P = .012), higher human epidermal growth factor receptor 2 (HER-2) overexpression (IHC, P = .075), lymph node positivity (P = .008), higher grade tumors (P < .0001), and trends toward inferior disease-free survival (DFS; hazard ratio = 1.32; P = .094). Using genomic expression analysis, tumors arising in young women had significantly lower ERalpha mRNA (P < .0001), ERbeta (P = .02), and progesterone receptor (PR) expression (P < .0001), but higher HER-2 (P < .0001) and epidermal growth factor receptor (EGFR) expression (P < .0001). Exploratory analysis (GSEA) revealed 367 biologically relevant gene sets significantly distinguishing breast tumors arising in young women. Combining clinicopathologic and genomic variables among tumors arising in young women demonstrated that younger age and lower ERbeta and higher EGFR mRNA expression were significant predictors of inferior DFS.
This large-scale genomic analysis illustrates that breast cancer arising in young women is a unique biologic entity driven by unifying oncogenic signaling pathways, is characterized by less hormone sensitivity and higher HER-2/EGFR expression, and warrants further study to offer this poor-prognosis group of women better preventative and therapeutic options.
Learning Objectives
After completing this course, the reader will be able to:
Explain how tumor hypoxia affects radiation resistance.
Apply this understanding to clinical outcome in specific ...diseases.
Describe approaches for improving therapeutic outcome in anemia patients.
Access and take the CME test online and receive 1 hour of AMA PRA category 1 credit atCME.TheOncologist.com
Hypoxia is a common feature of solid tumors that occurs across a wide variety of malignancies. Hypoxia and anemia (which contributes to tumor hypoxia) can lead to ionizing radiation and chemotherapy resistance by depriving tumor cells of the oxygen essential for the cytotoxic activities of these agents. Hypoxia may also reduce tumor sensitivity to radiation therapy and chemotherapy through one or more indirect mechanisms that include proteomic and genomic changes. These effects, in turn, can lead to increased invasiveness and metastatic potential, loss of apoptosis, and chaotic angiogenesis, thereby further increasing treatment resistance. Investigations of the prognostic significance of pretreatment tumor oxygenation status have shown that hypoxia (oxygen tension pO2 value ≤10 mmHg) is associated with lower overall and disease‐free survival, greater recurrence, and less locoregional control in head and neck carcinoma, cervical carcinoma, and soft‐tissue sarcoma. In view of the deleterious effect of hypoxia on standard cancer treatment, a variety of hypoxia‐ and anemia‐targeted therapies have been studied in an effort to improve therapeutic effectiveness and patient outcomes. Early evidence from experimental and clinical studies suggests the administration of recombinant human erythropoietin (rHuEPO) may enhance the effectiveness of radiation therapy and chemotherapy by increasing hemoglobin levels and ameliorating anemia in patients with disease‐ or treatment‐related anemia. However, further research is needed in the area of hypoxia‐related treatment resistance and its reversal.
An independent Adjuvant Cardiac Review and Evaluation Committee (ACREC) systematically reviewed cases of symptomatic heart failure events to uniformly define the cardiac event rate across two large ...trials (National Surgical Adjuvant Breast and Bowel Project NSABP B-31 and North Central Cancer Treatment Group NCCTG N9831) that assessed the addition of trastuzumab to standard adjuvant chemotherapy.
The committee was composed of six independent oncologists and cardiologists. A retrospective review of patients with a cardiac event was performed by the primary investigators of the trials. The ACREC prospectively established criteria for determining a symptomatic heart failure event. Recovery status was determined from documented resolution of signs and symptoms. Potential risk factors were also assessed.
Medical records for a total of 173 patients were reviewed: 40 in the chemotherapy-alone arm and 133 in the trastuzumab arm. Trastuzumab-treated patients had a 2.0% incidence of symptomatic heart failure events compared with 0.45% in the chemotherapy-alone arm. Complete or partial recovery was observed in 86.1% of trastuzumab-treated patients with symptomatic heart failure events. Of five patients who died, only one patient had received trastuzumab. Independent predictors for cardiac events were age older than 50 years, a low ejection fraction at the start of paclitaxel treatment, and trastuzumab treatment.
The incidence of symptomatic heart failure events is 2.0% in patients treated with adjuvant trastuzumab, and the majority of these patients recover with appropriate treatment.
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