Poly (ADP-ribose) polymerase inhibition enhances trastuzumab antitumour activity in HER2 overexpressing breast cancer

AimPoly (ADP-ribose) polymerase (PARP) inhibitors have shown promising results in Breast Cancer (BRCA) deficient breast cancer, but not in molecularly unselected patient populations. Two lines of research in this field are needed: the identification of novel subsets of patients that could potentially benefit from PARP inhibitors and the discovery of suitable targeted therapies for combination strategies.MethodsWe tested PARP inhibition, alone or combined with the anti-HER2 antibody trastuzumab on HER2+ breast cancer. We used two PARP inhibitors in clinical development, olaparib and rucaparib, as well as genetic downmodulation of PARP-1 for in vitro studies. DNA damage was studied by the formation of γH2AX foci and comet assay. Finally, the in vivo anti-tumour effect of olaparib and trastuzumab was examined in nude mice subcutaneously implanted with BT474 cells.ResultsIn a panel of four HER2 overexpressing breast cancer cell lines, both olaparib and rucaparib significantly decreased cell growth and enhanced anti-tumour effects of trastuzumab. Cells exposed to olaparib and trastuzumab had greater DNA damage than cells exposed to each agent alone. Mechanistic exploratory assays showed that trastuzumab downmodulated the homologous recombination protein proliferating cell nuclear antigen (PCNA). Combination treatment in the BT474 xenograft model resulted in enhanced growth inhibition, reduced tumour cell proliferation, and increased DNA damage and apoptosis.ConclusionTaken together, our results show that PARP inhibition has antitumour effects and increases trastuzumab activity in HER2 overexpressing breast cancer. These findings make this novel combination a promising strategy for clinical development.     

Increased mortality in HER2 positive, oestrogen receptor positive invasive breast cancer: a population-based study

Background:

This study assessed the impact of human epidermal growth factor receptor 2 (HER2) status on the outcomes in an unselected population of breast cancer patients who did not receive HER2-targeted therapy.

Methods:

HER2 status by immunohistochemistry and fluorescence in situ hybridisation was compared with clinicopathological data, overall survival (OS) and disease-free survival (DFS) for all patients presenting with breast cancer over 3 years.

Results:

In 865 patients (median follow up 6.02 years), HER2 positivity was identified in 13.3% of all cancers and was associated with higher tumour grade (P<10⁻⁸), lymphovascular invasion (P<0.001) and axillary nodal metastasis (P=0.003). There was a negative association with oestrogen-receptor (ER) and progesterone-receptor expression (P<10⁻⁸), but the majority (57%) of HER2+tumours were ER+HER2 positivity was associated with poorer OS (P=0.0046) and DFS (P=0.0001) confined to the lymph node-positive (LN+) and ER+ subgroups.

Conclusion:

HER2-positive cancers were less common in this population-based cohort than most selected series. The association of HER2 positivity with poor prognosis was confined to the ER+ and LN+ subgroups. The survival deficit for the 7.5% of patients with ER+/HER2+ cancer compared with ER+/HER2– patients points to a significant subgroup of women who may not (currently) be considered for HER2-directed therapy.     

曲妥珠单抗耐药后HER 2阳性转移性乳腺癌靶向治疗策略

人表皮生长因子受体2（human epidermal growth factor receptor 2,HER 2）是一种跨膜酪氨酸激酶受体,可以激活下游一系列信号通路,导致肿瘤细胞增殖和存活。HER 2阳性乳腺癌是乳腺癌的特殊类型,恶性程度高,预后差。抗HER 2单克隆抗体曲妥珠单抗能够改善该类乳腺癌治疗效果,但最终仍难逃耐药的结局。近年来,针对曲妥珠单抗耐药机制的研究、新型靶向药物的研发以及治疗策略的探索,在克服曲妥珠单抗耐药性方面取得了重大进展,本文将对其耐药后治疗策略及临床试验数据进行综述。     

Beyond trastuzumab: novel therapeutic strategies in HER2-positive metastatic breast cancer

The use of trastuzumab, a monoclonal antibody that targets the human epidermal growth factor receptor 2 (HER2) alteration present in 25 to 30% of breast cancers, has been associated with improved survival outcomes in both the adjuvant and metastatic settings. However, despite the robust clinical efficacy of trastuzumab in HER2-positive metastatic breast cancer (MBC), primary and secondary resistance remains a clinical challenge. Although lapatinib has demonstrated modest activity in this setting, trials reported to date have yet to demonstrate improvements in overall survival with its use. Novel therapeutic strategies to circumvent trastuzumab resistance are warranted, and agents targeting the HER, vascular endothelial growth factor, heat shock protein 90, phosphoinositide 3 kinase/Akt/mammalian target of rapamycin, and insulin-like growth factor-1 receptor pathways represent rational approaches in the management of HER2-positive disease. In this review, early-phase and emerging trial data surrounding the use of these promising agents in HER2-positive MBC will be discussed.     

HER2-amplified breast cancer: mechanisms of trastuzumab resistance and novel targeted therapies

HER2 amplification is seen in up to 20% of breast cancers and is associated with an aggressive phenotype. Trastuzumab, a monoclonal antibody to HER2, accrues significant clinical benefit in the metastatic and adjuvant settings. However, some patients suffer disease recurrence despite adjuvant trastuzumab therapy, and many patients with metastatic disease do not respond to therapy or develop refractory disease within 1 year of treatment. Given the increased recognition of de novo and acquired resistance to therapy, considerable research has been dedicated to understanding the molecular mechanisms of trastuzumab resistance. Here, we highlight putative models of resistance, including activation of the downstream PI3K-signaling pathway, accumulation of a constitutively active form of HER2, and crosstalk of HER2 with other growth factor receptors. The identification of these specific mechanisms of trastuzumab resistance has provided a rationale for the development of several novel HER2-targeted agents as the mechanisms have largely suggested a continued tumor dependence on HER2 signaling. We explore the emerging data for the treatment of trastuzumab-refractory disease with novel agents including lapatinib, neratinib, pertuzumab, trastuzumab-DM1, HSP90 and PI3K pathway inhibitors, and the future potential for these inhibitors which, if combined with reliable biomarkers of resistance, may ultimately usher in a new era of personalized medicine for this disease.     

Reactive stroma and trastuzumab resistance in HER2-positive early breast cancer

We investigated the value of reactive stroma as a predictor for trastuzumab resistance in patients with early HER2-positive breast cancer receiving adjuvant therapy. The pathological reactive stroma and the mRNA gene signatures that reflect reactive stroma in 209 HER2-positive breast cancer samples from the FinHer adjuvant trial were evaluated. Levels of stromal gene signatures were determined as a continuous parameter, and pathological reactive stromal findings were defined as stromal predominant breast cancer (SPBC; ≥50% stromal) and correlated with distant disease-free survival. Gene signatures associated with reactive stroma in HER2-positive early breast cancer (N = 209) were significantly associated with trastuzumab resistance in estrogen receptor (ER)-negative tumors (hazard ratio [HR] = 1.27 p interaction = 0.014 [DCN], HR = 1.58, p interaction = 0.027 [PLAU], HR = 1.71, p interaction = 0.019 [HER2STROMA, novel HER2 stromal signature]), but not in ER-positive tumors (HR = 0.73 p interaction = 0.47 [DCN], HR = 0.71, p interaction = 0.73 [PLAU], HR = 0.84; p interaction = 0.36 [HER2STROMA]). Pathological evaluation of HER2-positive/ER-negative tumors suggested an association between SPBC and trastuzumab resistance. Reactive stroma did not correlate with tumor-infiltrating lymphocytes (TILs), and the expected benefit from trastuzumab in patients with high levels of TILs was pronounced only in tumors with low stromal reactivity (SPBC <50%). In conclusion, reactive stroma in HER2-positive/ER-negative early breast cancer tumors may predict resistance to adjuvant trastuzumab therapy.     

Population pharmacokinetics of trastuzumab in patients With HER2+ metastatic breast cancer

Purpose: To characterize the population pharmacokinetics of trastuzumab in patients with metastatic breast cancer. Methods: A nonlinear mixed effect model was based on pharmacokinetic data from phase I, II, and III studies of 476 patients. The phase I study enrolled patients with advanced solid tumors. The phase II and III studies enrolled patients with HER2-positive metastatic breast cancer. Patients in the pivotal phase II and III studies were treated with a 4 mg/kg loading dose of trastuzumab followed by 2 mg/kg weekly for up to 840 days. The model adequately predicted observed trastuzumab concentrations. Model stability and performance were verified using bootstrap simulations. Percentiles, mean, and standard deviation of observed levels were compared with their distributions from 100 replicates of datasets simulated under the model. Results: A two-compartment linear pharmacokinetic model best described the data and accounted for the long-term accumulation observed following weekly administration of trastuzumab. Population estimates from the base model for clearance (CL) and volume of distribution of the central compartment (V₁) of trastuzumab were 0.225 L/day, and 2.95 L, respectively. Estimated terminal halflife (t_1/2) based on the population estimate was 28.5 days. Interpatient variabilities in clearance and volume were 43 and 29%, respectively. The number of metastatic sites, plasma level of extracellular domain of the HER2 receptor, and patient weight were significant baseline covariates for clearance, volume, or both (P<0.005). However, these covariate effects on trastuzumab exposure were modest and not clinically important in comparison with the large inter-patient variability of CL. Concomitant chemotherapy (anthracycline plus cyclophosphamide, or paclitaxel) did not appear to influence clearance. Conclusion: This population pharmacokinetic model can predict trastuzumab exposure in the long-term treatment of patients with metastatic breast cancer and provide comparison of alternative dosage regimens via simulation.     

Hormone-receptor expression and activity of trastuzumab with chemotherapy in HER2-positive advanced breast cancer patients

BACKGROUND:

The relationship between quantitative immunohistochemical hormone receptor expression and response to the combination of trastuzumab with chemotherapy in HER2‐positive advanced breast cancer is currently unknown.

METHODS:

Estrogen receptor (ER) and progesterone receptor expression was studied both as a dichotomous variable (positivity set at ≥1% of positive cells) and as a continuous variable. The effect of hormone receptor expression on overall response rate and progression‐free survival in patients receiving trastuzumab‐based treatment was studied by univariate and multivariate analysis.

RESULTS:

One hundred eleven of 227 consecutive advanced breast cancer patients treated at 2 Institutions had hormone receptor‐positive tumors (49%). High expression of ER (≥30% of tumor cells) predicted reduced probability of tumor response to trastuzumab plus chemotherapy (multivariate odds ratio, 0.422; 95% confidence interval [CI], 0.222‐0.803; P = .009). In patients with hormone receptor‐positive tumors (≥1% of tumor cells), maintenance endocrine therapy added to trastuzumab upon the completion of chemotherapy was associated with a significant progression‐free survival benefit (hazard ratio, 0.521; 95% CI, 0.3325‐0.836; P = .007).

CONCLUSIONS:

Our results suggest a predictive role of hormone receptor expression in HER2‐positive tumors. Further investigation in this patient subset is warranted to optimize the use of HER2‐targeting agents, chemotherapy, and endocrine therapy. Cancer 2012;. © 2011 American Cancer Society.     

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.     

Nuclear HER4 mediates acquired resistance to trastuzumab and is associated with poor outcome in HER2 positive breast cancer

The role of HER4 in breast cancer is controversial and its role in relation to trastuzumab resistance remains unclear. We showed that trastuzumab treatment and its acquired resistance induced HER4 upregulation, cleavage and nuclear translocation. However, knockdown of HER4 by specific siRNAs increased trastuzumab sensitivity and reversed its resistance in HER2 positive breast cancer cells. Preventing HER4 cleavage by a γ-secretase inhibitor and inhibiting HER4 tyrosine kinase activity by neratinib decreased trastuzumab-induced HER4 nuclear translocation and enhanced trastuzumab response. There was also increased nuclear HER4 staining in the tumours from BT474 xenograft mice and human patients treated with trastuzumab. Furthermore, nuclear HER4 predicted poor clinical response to trastuzumab monotherapy in patients undergoing a window study and was shown to be an independent poor prognostic factor in HER2 positive breast cancer. Our data suggest that HER4 plays a key role in relation to trastuzumab resistance in HER2 positive breast cancer. Therefore, our study provides novel findings that HER4 activation, cleavage and nuclear translocation influence trastuzumab sensitivity and resistance in HER2 positive breast cancer. Nuclear HER4 could be a potential prognostic and predictive biomarker and understanding the role of HER4 may provide strategies to overcome trastuzumab resistance in HER2 positive breast cancer.     

Trastuzumab‐based neoadjuvant therapy in patients with HER2‐positive breast cancer

Overexpression, or gene amplification, of the human epidermal growth factor receptor 2 (HER2) is evident in 20% to 25% of breast cancers. The biologic agent trastuzumab is an HER2‐targeted monoclonal antibody that inhibits the proliferation of tumor cells and induces tumor cell death through multiple mechanisms of action. Currently, trastuzumab is approved for use in the adjuvant and metastatic settings. Trials combining trastuzumab with neoadjuvant chemotherapy suggest that patients with HER2‐positive breast cancer also may benefit from preoperative trastuzumab. For this article, the author reviewed efficacy and safety data from key studies of patients who received neoadjuvant trastuzumab‐based therapy. Studies were identified from literature searches of publication and congress databases. The results of 3 large phase 3 trials (the M. D. Anderson Cancer Center neoadjuvant trastuzumab trial, the Neoadjuvant Herceptin [NOAH] trial, and the German Breast Group/Gynecologic Oncology Study Group “GeparQuattro” trial) demonstrated that, compared with chemotherapy alone, neoadjuvant trastuzumab plus chemotherapy significantly increased pathologic complete response rates to as high as 65%. Improvements in disease‐free, overall, and event‐free survival also were reported in the NOAH trial. In addition to demonstrated efficacy, a low incidence of cardiac dysfunction suggests that neoadjuvant trastuzumab is both effective and well tolerated. Similar results have been reported in a range of phase 2 studies using different trastuzumab‐based regimens. These encouraging data led the National Comprehensive Cancer Network to recommend treating patients who have operable, locally advanced, HER2‐positive breast cancer with neoadjuvant paclitaxel plus trastuzumab followed by 5‐fluorouracil, epirubicin, and cyclophosphamide plus trastuzumab. Cancer 2010. © 2010 American Cancer Society.     

Adjuvant trastuzumab with chemotherapy is effective in women with small, node-negative, HER2-positive breast cancer

BACKGROUND:

Several large, randomized trials established the benefits of adjuvant trastuzumab with chemotherapy. However, the benefit for women with small, node‐negative HER2‐positive (HER2+) disease is unknown, as these patients were largely excluded from these trials. Therefore, a retrospective, single‐institution, sequential cohort study of women with small, node‐negative, HER2+ breast cancer who did or did not receive adjuvant trastuzumab was conducted.

METHODS:

Women with ≤2 cm, node‐negative, HER2+ (immunohistochemistry 3+ or fluorescence in situ hybridization ≥2) breast cancer were identified through an institutional database. A “no‐trastuzumab” cohort of 106 trastuzumab‐untreated women diagnosed between January 1, 2002 and May 14, 2004 and a “trastuzumab” cohort of 155 trastuzumab‐treated women diagnosed between May 16, 2005 and December 31, 2008 were described. Survival and recurrence outcomes were estimated by Kaplan‐Meier methods.

RESULTS:

The cohorts were similar in age, median tumor size, histology, hormone receptor status, hormone therapy, and locoregional therapy. Chemotherapy was administered in 66% and 100% of the “no trastuzumab” and “trastuzumab” cohorts, respectively. The median recurrence‐free and survival follow‐up was: 6.5 years (0.7‐8.5) and 6.8 years (0.7‐8.5), respectively, for the “no trastuzumab” cohort and 3.0 years (0.5‐5.2) and 3.0 years (0.6‐5.2), respectively, for the “trastuzumab” cohort. The 3‐year locoregional invasive recurrence‐free, distant recurrence‐free, invasive disease‐free, and overall survival were 92% versus 98% (P = .0137), 95% versus 100% (P = .0072), 82% versus 97% (P < .0001), and 97% versus 99% (P = .18) for the “no trastuzumab” and “trastuzumab” cohorts, respectively.

CONCLUSIONS:

Women with small, node‐negative, HER2+ primary breast cancers likely derive significant benefit from adjuvant trastuzumab with chemotherapy. Cancer 2011;. © 2011 American Cancer Society.     

Efficacy of neoadjuvant therapy with trastuzumab concurrent with anthracycline- and nonanthracycline-based regimens for HER2-positive breast cancer

BACKGROUND:

The aim of this study was to evaluate the pathologic complete response (pCR) rates and relapse‐free survival (RFS) and overall survival (OS) of patients receiving neoadjuvant systemic therapy (NST) with trastuzumab in combination with an anthracycline‐ or nonanthracycline‐based regimen.

METHODS:

In this retrospective nonrandomized study, the authors reviewed records of 300 patients with HER2‐positive breast cancer treated with either sequential paclitaxel and trastuzumab and FEC75 in combination with trastuzumab (PH‐FECH) or docetaxel, carboplatin, and trastuzumab (TCH). The Kaplan‐Meier product‐limit method was used to estimate RFS and OS rates. Logistic regression models and Cox proportional hazards models were fit to determine the associations between NST, pCR, and survival.

RESULTS:

There was no significant difference in the decline in cardiac ejection fraction; however, patients who received PH‐FECH had fewer cardiac comorbidities at baseline (P = .002). pCR rates were 60.6% and 43.3% for patients who received PH‐FECH (n = 235) and TCH (n = 65), respectively (P = .016). Patients who received PH‐FECH were 1.45 times more likely to have a pCR (odds ratio [OR], 1.45; 95% confidence interval [CI], 1.06‐1.98; P = .02). Three‐year RFS rates were 93% and 71% (P < .001), and 3‐year OS rates were 96% and 86% (P = .008) for patients who received PH‐FECH and TCH, respectively. Patients who received PH‐FECH had a lower risk of recurrence (hazard ratio [HR], 0.27; 95% CI, 0.12‐0.60; P = .001) and death (HR, 0.37; 95% CI, 0.12‐1.13; P = .08) than those treated with TCH.

CONCLUSIONS:

The type of NST in HER2‐positive breast cancer is predictive of pCR rate independent of disease and patient characteristics. Although TCH is active, PH‐FECH shows a higher pCR rate and RFS advantage. Cancer 2012. © 2011 American Cancer Society.     

Patritumab plus trastuzumab and paclitaxel in human epidermal growth factor receptor 2‐overexpressing metastatic breast cancer

Human epidermal growth factor receptor 3 (HER3) expression in lung and breast cancers has a negative impact on survival. Patritumab, a human anti‐HER3 mAb, has shown anticancer activity in preclinical models. This study examined the safety and pharmacokinetics of patritumab in combination with trastuzumab and paclitaxel in patients with HER2‐overexpressing metastatic breast cancer. In this open‐label, multicenter, dose‐escalation, phase Ib study, patients received patritumab 9 or 18 mg/kg plus trastuzumab and paclitaxel at known tolerated doses. Safety and tolerability were assessed based on dose‐limiting toxicities and other non‐life threatening adverse events. The pharmacokinetic profile for patritumab was determined based on the target trough level. Clinical efficacy was evaluated based on the overall response rate and progression‐free survival. Six patients received patritumab 9 mg/kg and 12 received 18 mg/kg. The most common adverse events were diarrhea, alopecia, leukopenia, neutropenia, and maculopapular rash. No dose‐limiting toxicities were observed. The target trough serum concentration was achieved in all patients at a dose of 18 mg/kg. Overall response rate was 38.9% and median progression‐free survival was 274 days. In conclusion, patritumab plus trastuzumab and paclitaxel was tolerable and efficacious at both doses. We recommend the dose level of 18 mg/kg for future phase II studies. (Clinical trial registration: JapicCTI‐121772.)