Phosphorylated HER-2 tyrosine kinase and Her-2/neu gene amplification as predictive factors of response to trastuzumab in patients with HER-2 overexpressing metastatic breast cancer (MBC)

https://doi.org/10.1016/j.ejca.2006.11.019Get rights and content

Abstract

Aim

Trastuzumab (T), a humanised monoclonal antibody against HER-2, is active in HER-2-positive MBC patients. However, nearly 60% of the patients do not benefit from T, stressing the need for additional predictive markers. The following markers could be implicated in response to T: (1) the magnitude of Her-2 gene amplification; (2) the co-expression of the other HER family receptors, possibly responsible for HER-2 trans-activation; (3) the activated status of HER-2; (4) the activated status of downstream effectors as mitogen-activated protein kinases (MAPKs), p38 and p27.

Methods

Medical files of patients with MBC treated with T either as a single agent or in combination with chemotherapy (CT) were reviewed. HER family members (EGFR, HER-2, HER-3, HER-4), the phosphorylated forms of EGFR (p-EGFR), HER-2 (p-HER-2) and of the downstream effectors were evaluated in the archival tumours. The correlation between clinical outcome and the expression of these markers was investigated.

Results

(1) Increasing values of Her-2 amplification were associated with a higher probability of achieving an objective response; (2) no statistical significant correlation between the expression of the HER family receptors was found; (3) p-HER-2 was predictive of response in patients treated with T + CT; (4) a statistically significant correlation between p-ERK 1/2, p-p38 and p-HER-2 emerged, pointing to the activated vertical pathway p-HER-2  p-MAPKs.

Conclusions

p-HER-2 and the magnitude of Her-2 amplification were predictive of response to T and their role deserves to be analysed in larger and more homogenous T-treated populations such as those from large phase III trials.

Introduction

The epidermal growth factor receptor family (HER family) belongs to the receptor tyrosine kinases (RTKs) superfamily, which accounts for about 20 subclasses extensively implicated in proliferation, differentiation and survival pathways, both in normal and in cancer cells. The HER family includes four members, the EGFR or ErbB1/HER-1, ErbB2/HER-2, ErbB3/HER-3 and ErbB4/HER-4, which share a high homology in their structure. Deregulation with consequent aberrant function of the four HER receptors may be mainly related to their overexpression due to gene amplification, their trans-activation as a consequence of heterodimerisation or to intragenic mutations.

HER-2 overexpression is found in 25–30% of human breast cancers (BC) and is associated with worse outcome in terms of high risk of relapse, disease progression and shorter survival.1, 2, 3, 4, 5

Monoclonal antibodies directed against the external domain of the HER receptors and small tyrosine kinase inhibitors (TKIs) targeting their cytoplasmic part represent the main attempts at blocking abnormal signals promoted by these receptors. The first anti-HER-2 agent to be approved for use in clinical practice is the humanised monoclonal antibody T (Herceptin®; Genentech, South San Francisco, CA, USA).6 An important body of data substantiates T efficacy in patients with HER-2 overexpressing MBC, both when the drug is given as a single agent and in combination with CT, with the latter modality improving survival.7, 8, 9 Given alone as first line treatment to MBC patients, T shows an overall response (OR) rate of 38% and a CB of 48%.8 Therefore, more than half of HER-2 amplified MBC patients exhibit primary resistance to T.

Resistance to HER-2 targeting drugs can be: (1) ‘primary’ or ‘pan-HER-2’: resistance to all anti-HER-2 drugs from the start; (2) ‘agent-selective’: tumours rely on HER-2 signalling but are resistant only to specific therapies, e.g. tumours are sensitive to T but resistant to TKIs or vice versa; (3) ‘acquired’: resistance occurs after an initial response to T.10

To understand the mechanisms of resistance to T, it is important to take into account its mechanisms of action. Although not completely defined they include: (a) down-regulation of the receptor, (b) blockade of the interaction with the other HER, thus avoiding the heterodimerisation responsible for HER-2 trans-activation, (c) antibody-dependent cell-mediated cytotoxicity, (d) reduction of the proteolytic cleavage of the ectodomain, thus preventing the formation of a truncated highly active receptor remnant, (e) the induction of p27 with consequential cellular arrest in G1 phase, (f) anti-angiogenic activity,11, 12, 13, 14, 15, 16 and (g) inhibition of PI3K/Akt and MAPKs pathways.17, 18, 19

The additive/synergistic effect of T with cytotoxic drugs, such as cisplatin, paclitaxel and anthracyclines, has been reported20 and there is consistent evidence that HER-2 modifies the sensitivity of BC cells to several CT drugs.21 For taxanes, preclinical data have shown that by treating the intrinsic taxane-resistant p185erbB2 overexpressing BC cell lines with T, the sensitivity to these drugs could be restored.22 HER-2 overexpression inhibits p34Cdc2, a critical kinase in paclitaxel-induced apoptosis. T-induced downregulation of HER-2 causes upregulation of p21Cip1, with consequent p34Cdc2 activation and paclitaxel-induced apoptosis.23, 24 These data were confirmed in clinical studies with better RR, time to progression (TTP) and overall survival (OS) with the combination of T with taxanes.

In the clinical setting, no other biomarkers besides HER-2-positivity have been found to be predictive of response to T. However, since only about 40% of HER-2 overexpressing/amplified tumours respond to this agent, additional markers are urgently needed particularly in view of its foreseen wide use in the adjuvant setting.

The aim of this retrospective analysis was to identify these potential predictive factors of response to T. Our hypothesis was that the co-expression of other HER receptors, the phosphorylation of HER-2 tyrosine kinase and the activation of downstream effectors could provide a phenotype of resistance to T. Particularly, higher activity of the T was expected when intracellular pathways that it can block were activated. Moreover, based on data suggesting that in HER-2 transfected BC cells the magnitude of overexpression/amplification could play a role in responsiveness to T,25 we explored whether a threshold value of Her-2 amplification was required for T efficacy; the possible correlation between levels of Her-2 gene amplification and response was also analysed.

Section snippets

Study design

In Belgium, until May 2002, T (Herceptin®) was provided by F. Hoffman-La Roche Ltd., Basel, Switzerland, through two national compassionate use programmes, namely the Expanded Access Programme (EAP) and the Identified Patient Programme (IPP). Patients with MBC pretreated with at least two CT lines were allowed to receive T (EAP open until September 2000) as a single agent or in combination with CT, mainly paclitaxel. T as first line therapy was allowed only if given with paclitaxel within the

Results

We reviewed 248 medical files, with 122 patients registered in the EA and 126 in the IP programmes. Two populations were identified: (1) 105 patients that received single agent T and (2) 123 patients that received T + CT.

Among the patients who started the combination T + CT (mainly with paclitaxel), six patients received only one dose of CT (weekly regimens) and single agent T for the rest of their treatment; therefore for response to treatment analysis they were included in T-alone population.

Discussion

We report the results of a retrospective study aiming at finding better predictive factors of response/resistance to T, in 103 HER-2-overexpressing MBC patients treated with single agent T (46 patients) or with T + CT (57 patients).

More than half of the initially identified population was not eligible mainly due to technical problems related to the archival samples (e.g.: HER-2 overexpression not confirmed centrally, no remaining invasive cancer) or to the lack of the objective evaluation of the

Conflict of interest statement

None declared.

Acknowledgements

The authors thank Dr. Ahmad Awada (Medical Oncology, Jules Bordet Institute, Brussels, Belgium) and Dr. Laura Biganzoli (Medical Oncology, Jules Bordet Institute, Brussels, Belgium) for the independent response review; Dr. Emmanuelle Dochy (Medical Oncology, Jules Bordet Institute, Brussels, Belgium), Dr. Claudia Ferrara (Medical Oncology, Naples, Italy), Dr. Marta Pestrin (Medical Oncology, Udine, Italy), Dr. Chantal Bernard (Medical Oncology, Jules Bordet Institute, Brussels, Belgium), Ms.

References (50)

  • Y. Yarden et al.

    Untangling the ErbB signalling network

    Nat Rev Mol Cell Biol

    (2001)
  • D.J. Slamon et al.

    Human breast cancer: correlation of relapse and survival with amplification of the HER2/neu oncogene

    Science

    (1987)
  • P. Carter et al.

    Humanization of an anti-p185HER2 antibody for human cancer therapy

    Proc Natl Acad Sci USA

    (1992)
  • M.A. Cobleigh et al.

    Multinational study of the efficacy and safety of humanized anti-HER2 monoclonal antibody in women who have HER2 overexpressing metastatic breast cancer that has progressed after chemotherapy for metastatic disease

    J Clin Oncol

    (1999)
  • C.L. Vogel et al.

    Efficacy and safety of T as single agent in first-line treatment of HER2-overexpressing metastatic breast cancer

    J Clin Oncol

    (2002)
  • D.J. Slamon et al.

    Use of chemotherapy plus a monoclonal antibody against HER2 for metastatic breast cancer that overexpresses HER2

    N Engl J Med

    (2001)
  • M. Ellis

    Overcoming endocrine therapy resistance by signal transduction inhibition

    The Oncologist

    (2004)
  • J. Baselga et al.

    Mechanism of action of anti-HER2 monoclonal antibodies

    Ann Oncol

    (2001)
  • M.A. Molina et al.

    T (Herceptin), a humanized anti-Her2 receptor monoclonal antibody, inhibits basal and activated Her2 ectodomain cleavage in breast cancer cells

    Cancer Res

    (2001)
  • F. Cardoso et al.

    Resistance to T: a necessary evil or a temporary challenge?

    Clin Breast Cancer

    (2000)
  • X.-F. Le et al.

    HER-2 targeting antibodies modulate the cyclin-dependent kinase inhibitor p27kip1 via multiple signalling pathways

    Cell Cycle

    (2005)
  • M.F. Yakes et al.

    Herceptin-induced inhibition of Phosphatidylinositol-3 Kinase and Akt is required for antibody-mediated effects on p27, cyclin D1, and antitumor action

    Cancer Res

    (2002)
  • A.S. Clark et al.

    Constitutive and inducible Akt activity promotes resistance to chemotherapy, T, or tamoxifen in breast cancer cells

    Mol Cancer Ther

    (2002)
  • M. Pegram et al.

    Inhibitory effects of combinations of HER2/neu antibody and chemotherapeutic agents used for treatment of human breast cancer

    Oncogene

    (1999)
  • D. Yu et al.

    Role of erbB2 in breast cancer chemosensitivity

    BioEssays

    (2000)
  • Cited by (46)

    • Computer-aided scoring of erb-b2 receptor tyrosine kinase 2 (HER2) gene amplification status in breast cancer

      2022, Journal of Pathology Informatics
      Citation Excerpt :

      Although evaluation of HER2 protein expression and gene amplification are routinely used to identify patients for HER2 targeted therapy, efforts have been made to utilize data regarding HER2 amplification and expression to provide additional diagnostic insights. Data suggest that increased HER2 amplification may predict pathologic complete response in the neoadjuvant setting,30–32 as well as predict progression-free survival in metastatic patients.33 Similarly, characterization of HER2 intratumoral heterogeneity may act as a predictor for therapeutic response.34–36

    • HER2 immunohistochemistry staining positivity is strongly predictive of tumor response to neoadjuvant chemotherapy in HER2 positive breast cancer

      2020, Pathology Research and Practice
      Citation Excerpt :

      They found that high HER2 copy number was consistently associated with better response [39]. A meta-analysis showed that high amplification of HER2 or high level of mRNA expression had a positive correlation with response to trastuzumab and survival in patients with metastatic HER + breast cancer [40,41]. In a study with trastuzumab-based neoadjuvant therapy, the pCR rate in tumors with high HER2 gene amplification (>10.0 HER2 gene copies per cell) was significantly higher than that in tumors with low HER2 gene amplification (6–10 HER2 gene copies per cell), (56 % vs. 22 %; P < 0.005) [42].

    • The European Society of Breast Cancer Specialists recommendations for the management of young women with breast cancer

      2012, European Journal of Cancer
      Citation Excerpt :

      As recommended for early breast cancer, also in the metastatic setting, age alone should not be a reason to prescribe more aggressive therapy. There are few proven standards of care in MBC management overall86,95–100 and even fewer in young women. Therefore, inclusion of patients in well-designed, independent, prospective randomised trials must be a priority whenever available.

    • Long-term follow-up of HER2-overexpressing stage II or III breast cancer treated by anthracycline-free neoadjuvant chemotherapy

      2011, Annals of Oncology
      Citation Excerpt :

      In HER2-positive tumors, additionally to the tumors completely eradicated after trastuzumab-based therapy, a great number of the tumors do present a major clinical and histological response (96% in the TAXHER trial [3] and 95% in the GETN(A) trial [4]) with only few residual carcinoma cells making the pCR role in prognosis difficult to demonstrate. Additionally, if HER2 positivity is a major factor of response to trastuzumab [33, 34], HER2 positivity could be also a factor of relapse and the association between pCR rate and RFS gives conflicting results, being sometimes statistically associated [18] but sometimes not [21, 22]. Multivariate analysis of RFS showed that RFS was worse when persistent nodal invasion was diagnosed after surgery.

    View all citing articles on Scopus

    This work partially funded by ‘Les Amis de L’Institut Bordet’ and by F. Hoffman-La Roche Ltd.

    View full text