曲妥珠单抗治疗HER2+乳腺癌的临床进展

临床研究显示曲妥珠单抗与化疗联合用于人表皮生长因子受体2(HER2)+转移性乳腺癌的治疗以及早期乳腺癌的新辅助和辅助治疗,能显著延长患者的生存时间.其与内分泌治疗联合治疗HER2+且雌激素受体阳性的转移性乳腺癌,疗效优于单纯内分泌治疗.曲妥珠单抗联合其他靶向治疗药物,能够逆转肿瘤对曲妥珠单抗的耐药.疾病进展后继续应用曲妥珠单抗仍可使患者生存受益.     

曲妥珠单抗耐药机制及HER2阳性乳腺癌耐药后的治疗策略

曲妥珠单抗治疗人表皮生长因子受体2(Human epidermal growth factor receptor 2,HER2)阳性乳腺癌的效果确切,但高耐药率限制了其临床应用。本文对HER2阳性乳腺癌曲妥珠单抗耐药机制进行回顾与总结,并分析耐药后HER2阳性乳腺癌的治疗策略,以期为进一步的研究及临床治疗方案制定提供参考。     

Incorporating trastuzumab into the neoadjuvant treatment of HER2-overexpressing breast cancer

We sought to provide a brief overview of the available results of trastuzumab in the neoadjuvant treatment of women with locally advanced, HER2-overexpressing breast cancer. A review of published reports was conducted by the use of Medline computer searching and manual searching of abstracts presented at the Annual Meeting of the American Society of Clinical Oncology and the San Antonio Breast Cancer Symposium between 2002 and 2004. Several phase II trials and one phase III trial show that trastuzumab-containing regimens are feasible and yield high rates of clinical and pathologic complete response in women with locally advanced HER2-overexpressing breast cancer. Moreover, the neoadjuvant approach allows serial monitoring of biologic phenomena that occur during the administration of therapy, which acquires particular importance in the case of targeted therapies like trastuzumab. The incorporation of trastuzumab into neoadjuvant therapy for breast cancer appears promising. However, no data on long-term survival and safety are available at present. Well-designed clinical trials are needed to establish the optimal trastuzumab-based neoadjuvant strategy.     

Biweekly docetaxel and weekly trastuzumab treatment in HER 2-overexpressing metastatic breast cancer patients

Docetaxel and trastuzumab can be considered to be active drugs for HER 2-overexpressing metastatic breast cancer (MBC). This study was conducted to determine the activity of combination therapy with docetaxel and trastuzumab in MBC patients by assessing the response rate (RR), time to progression (TTP) and safety. We administered the combination of docetaxel 30-40 mg/m(2) biweekly and trastuzumab using a 4 mg/kg loading dose and thereafter 2 mg/kg weekly. Between October 2001 and December 2004, 14 patients with HER 2 positive (3+ by immunohistochemistry) MBC were enrolled in this study. The overall RR was 50.0% (7/14), with 1 CR, 6 PR, 3 NC and 4 PD. Median follow-up time was 15.0 months, while the median TTP was 10.8 months,and the median OS 21.8 months.     

Prognosis of patients with advanced gastric cancer by HER2 status and trastuzumab treatment

Background

The purpose of this study was to evaluate the impact of human epidermal growth factor receptor 2 (HER2) status and trastuzumab treatment on the prognosis of patients with advanced gastric cancer (AGC).

Methods

We retrospectively analyzed 364 AGC patients who received systemic chemotherapy. To evaluate the impact of trastuzumab exposure during any type of chemotherapy, our analysis used time-varying covariates to avoid a possible lead-time bias.

Results

Among the 364 patients, 58 (15.9 %) were HER2-positive. The median overall survival of the HER2-positive patients treated with trastuzumab (n = 43) was significantly longer than that of the HER2-negative patients [n = 306; 24.7 vs. 13.9 months, with an adjusted hazard ratio (HR) of 0.58; 95 % confidence interval (CI), 0.36–0.95; P = 0.03]. Notably, 22 patients continued with trastuzumab beyond the date of progression. By contrast, the HER2-positive patients not treated with trastuzumab (n = 15) showed survival similar to that of the HER2-negative patients (13.5 vs. 13.9 months, with an adjusted HR of 1.04; 95 % CI, 0.52–2.11; P = 0.91). According to the multivariate analysis, exposure to trastuzumab was independently associated with a better prognosis (HR 0.56; 95 % CI; 0.33–0.93; P = 0.026).

Conclusions

Recent HER2-positive AGC patients have a better prognosis than HER2-negative patients, particularly when treated with trastuzumab.     

Monitoring serum HER2 levels during neoadjuvant trastuzumab treatment within the GeparQuattro trial

In the context of neoadjuvant therapy (NT) for breast cancer patients, different targeted therapy approaches are currently evaluated in clinical trials. Serum markers could help to monitor and optimize such treatment strategies. We investigated human epidermal growth factor receptor 2 serum (sHER2) levels in 175 breast cancer patients participating in the GeparQuattro trial. This study incorporated NT approaches and additional trastuzumab treatment for all patients with HER2-positive tumors. Human epidermal growth factor receptor 2 serum levels were measured by enzyme-linked immunosorbent assay (ELISA) before initiation of NT and after NT (pre-surgery) in a HER2-positive (n = 90) and a HER2-negative patient cohort (n = 85). Median pre-chemotherapy sHER2 levels were higher in patients with positive HER2 status of the primary tumor than in patients with negative HER2 status (14.9 ng/ml vs. 7.7 ng/ml, P < 0.001). A pre-chemotherapy sHER2 cut-off level of 10 ng/ml had the best sensitivity and specificity in discriminating between HER2-positive and HER2-negative primary tumors. In HER2-positive patients, we found a significant positive association between pathological complete remission (pCR) and elevated sHER2 levels (above 15 ng/ml, P = 0.045) and a decrease of sHER2 levels during NT (P = 0.02), which was also significant in multivariate analysis (OR = 3.29, 95% CI 1.001–10.89, P = 0.049). In HER2-negative patients, we observed no association between sHER2 levels and pCR (P > 0.05). Monitoring sHER2 levels in the presence of anti-HER2 treatment might be an adjunct to the clinical evaluation during NT.     

Study of three-weekly docetaxel and weekly trastuzumab treatment in HER 2-overexpressing metastatic breast cancer patients

Docetaxel and trastuzumab can be considered to be active drugs for HER 2-overexpressing metastatic breast cancer (MBC). This study was conducted to determine the activity of combination therapy with docetaxel and trastuzumab in MBC patients (pts) by assessing the response rate (RR), time to progression (TTP) and safety. We administered the combination of docetaxel 70 mg/m2 every 3 weeks and trastuzumab using a 4 mg/kg loading dose and thereafter 2 mg/kg weekly. One cycle was three weeks. Between March 2002 and May 2003, 40 pts with HER 2-positive (3+by immunohistochemistry 39, FISH+1) MBC were enrolled in this study, and 39 pts proved eligible. The overall RR was 72% (28/39) [95%CI 55.1%-85.0%], with 6 CR, 22 PR, 7 SD, 1 PD and 3 NE. The median follow-up time was 14.3 months, while the TTP was 6.5 months (range, 0.6-19.8), median OS has not yet been reached. The number of pts assessable for safety was 40. Hematological Grade 3-4 toxicities were leukopenia 87.5% (35/40) and neutropenia 82.5% (33/40). Non-hematological Grade 3 toxicities were weight gain in 2 pts, and anorexia, neuropathy, fever and rash in one pt each. The combination of docetaxel and trastuzumab was a well-tolerated and very active regimen for the treatment of pts with HER 2-overexpressing MBC.     

HER2 testing and correlation with efficacy of trastuzumab therapy

The need for accurate detection of HER2 status is becoming more apparent, as therapeutic decisions are influenced by this information in both the adjuvant and advanced-stage setting. Since the US Food and Drug Administration approved trastuzumab (Herceptin) for the treatment of metastatic breast cancer, the urgency of accurately evaluating HER2 status of breast cancer specimens, in order to identify patients who might benefit from this therapy, has increased. A wide range of assay methods are available for determining HER2 status, but immunohistochemistry followed by fluorescence in situ hybridization (FISH) is the recommended approach for ambiguous cases. FISH is not as widely available and is more costly than immunohistochemistry, but economic modeling shows that it is the most effective (and cost-effective) option.     

HER2 therapy: Molecular mechanisms of trastuzumab resistance

Trastuzumab is a monoclonal antibody targeted against the HER2 tyrosine kinase receptor. The majority of patients with metastatic breast cancer who initially respond to trastuzumab develop resistance within one year of treatment initiation, and in the adjuvant setting 15% of patients still relapse despite trastuzumab-based therapy. In this review, we discuss potential mechanisms of antitumor activity by trastuzumab, and how these mechanisms become altered to promote therapeutic resistance. We also discuss novel therapies that may improve the efficacy of trastuzumab, and that offer hope that the survival of breast cancer patients with HER2-overexpressing tumors can be vastly improved.     

Neratinib overcomes trastuzumab resistance in HER2 amplified breast cancer

Trastuzumab has been shown to improve the survival outcomes of HER2 positive breast cancer patients. However, a significant proportion of HER2-positive patients are either inherently resistant or develop resistance to trastuzumab. We assessed the effects of neratinib, an irreversible panHER inhibitor, in a panel of 36 breast cancer cell lines. We further assessed its effects with or without trastuzumab in several sensitive and resistant breast cancer cells as well as a BT474 xenograft model. We confirmed that neratinib was significantly more active in HER2-amplified than HER2 non-amplified cell lines. Neratinib decreased the activation of the 4 HER receptors and inhibited downstream pathways. However, HER3 and Akt were reactivated at 24 hours, which was prevented by the combination of trastuzumab and neratinib. Neratinib also decreased pHER2 and pHER3 in acquired trastuzumab resistant cells. Neratinib in combination with trastuzumab had a greater growth inhibitory effect than either drug alone in 4 HER2 positive cell lines. Furthermore, trastuzumab in combination with neratinib was growth inhibitory in SKBR3 and BT474 cells which had acquired resistance to trastuzumab as well as in a BT474 xenograft model. Innately trastuzumab resistant cell lines showed sensitivity to neratinib, but the combination did not enhance response compared to neratinib alone. Levels of HER2 and phospho-HER2 showed a direct correlation with sensitivity to neratinib. Our data indicate that neratinib is an effective anti-HER2 therapy and counteracted both innate and acquired trastuzumab resistance in HER2 positive breast cancer. Our results suggest that combined treatment with trastuzumab and neratinib is likely to be more effective than either treatment alone for both trastuzumab-sensitive breast cancer as well as HER2-positive tumors with acquired resistance to trastuzumab.     

Adjuvant trastuzumab therapy for HER2-positive breast cancer

HER2 is overexpressed or gene amplified in 20%-25% of breast cancers. The anti-HER2 monoclonal antibody trastuzumab targets HER2-positive tumors, inhibiting proliferation and inducing cell death via extracellular and intracellular mechanisms. The clinical benefits observed with trastuzumab in the metastatic setting provided the rationale for assessing trastuzumab in the treatment of early breast cancer. Four large phase III adjuvant trials (NSABP B-31, NCCTG N9831, HERA, and BCIRG 006) investigated the efficacy and safety of 1 or 2 years of trastuzumab given in combination with or after standard adjuvant chemotherapy. The addition of 1 year of trastuzumab to adjuvant chemotherapy significantly improved disease-free survival (DFS) by 33%-52% and overall survival by 34%-41% in the 4 trials. The DFS benefits were observed regardless of age, nodal status, hormonal status, or tumor size in all trials. The cumulative incidence of congestive heart failure or cardiac death ranged from 0-0.9% in the control arms and 0-3.8% in the trastuzumab-containing arms. These were below the safety cutoff points set by the individual studies' independent data monitoring committees, indicating acceptable cardiac safety. Risk factors associated with cardiac dysfunction included baseline left ventricular ejection fraction level, hypertension, and older age. The addition of trastuzumab to adjuvant chemotherapy provides significant survival benefits with a positive benefit/risk ratio. Ongoing and planned trials correlated with basic science will enhance our understanding of HER2-positive disease, leading to treatment optimization and further improvements in patient outcomes.     

Cost-effectiveness analysis of trastuzumab in the adjuvant setting for treatment of HER2-positive breast cancer

BACKGROUND: Adding trastuzumab to adjuvant chemotherapy provides significant clinical benefit in patients with human epidermal growth factor receptor 2 (HER2)-positive breast cancer. A cost-effectiveness analysis was performed to assess clinical and economic implications of adding trastuzumab to adjuvant chemotherapy, based upon joint analysis of NSABP B-31 and NCCTG N9831 trials. METHODS: A Markov model with 4 health states was used to estimate the cost utility for a 50-year-old woman on the basis of trial results through 4 years and estimates of long-term recurrence and death based on a meta-analysis of trials. From 6 years onward, rates of recurrence and death were assumed to be the same in both trastuzumab and chemotherapy-only arms. Incremental costs were estimated for diagnostic and treatment-related costs. Analyses were from payer and societal perspectives, and these analyses were projected to lifetime and 20-year horizons. RESULTS: Over a lifetime, the projected cost of trastuzumab per quality-adjusted life year (QALY; discount rate 3%) gained was 26,417 dollars (range 9,104 dollars-69,340 dollars under multiway sensitivity analysis). Discounted incremental lifetime cost was 44,923 dollars, and projected life expectancy was 3 years longer for patients who received trastuzumab (19.4 years vs 16.4 years). During a 20-year horizon, the projected cost of adding trastuzumab to chemotherapy was 34,201 dollars per QALY gained. Key cost-effectiveness drivers were discount rate, trastuzumab price, and probability of metastasis. The cost-effectiveness result was robust to sensitivity analysis. CONCLUSIONS: Trastuzumab for adjuvant treatment of early stage breast cancer was projected to be cost effective over a lifetime horizon, achieving a cost-effectiveness ratio below that of many widely accepted oncology treatments.     

HER2/HER3 heterodimers and p21 expression are capable of predicting adjuvant trastuzumab response in HER2+ breast cancer

Human epidermal growth factor receptor 2 (HER2) plays an important role in breast cancer progression and provides predictive information for response to targeted therapy including trastuzumab although this is limited. Downstream pathways, such as PI3K/Akt, are associated with HER2/HER3 heterodimerization promoting survival and proliferation amongst cancer cells. Thus, patient outcome and trastuzumab therapy effectiveness might be further characterised by HER2/HER3 dimerisation and its signalling pathways. HER2/HER3 dimerisation status was assessed, using chromogenic in situ Proximity Ligation Assay, in two breast cancer series: early stage primary breast cancer, including 224 HER2+ patients that were not submitted to trastuzumab, and HER2+ breast cancer where patients were treated with adjuvant trastuzumab (n = 143). Levels of biomarkers including PI3K, pAKT, ER, PgR, HER3, BCL2, p53, PTEN and p21 were measured using immunohistochemistry. Levels of HER2/HER3 heterodimers were compared with biomarker expression and patient outcome. An association between high levels of HER2/HER3 dimerisation and absence of hormone receptors, ER and PgR, was observed. We further show for the first time the presence of HER2/HER3 heterodimers and the loss of p21 expression in HER2+ breast cancer predicts a significantly poorer outcome when submitted to adjuvant trastuzumab. Breast cancer patients that reveal high levels of HER2/HER3 dimerisation and loss of p21 are associated with poor survival prognosis in patients with HER2+ breast cancer treated with adjuvant trastuzumab. Further quantification analysis of HER dimer/ligand complexes and downstream signalling pathways will begin to unravel the complex associations with patient outcome and its relationship with sensitivity to targeted treatment.