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Effect of p95HER2/611CTF on the response to trastuzumab and chemotherapy.

ABSTRACT: Human epidermal growth factor receptor 2 (HER2)-positive breast cancers are currently treated with trastuzumab, an anti-HER2 antibody. About 30% of these tumors express a group of HER2 fragments collectively known as p95HER2. Our previous work indicated that p95HER2-positive tumors are resistant to trastuzumab monotherapy. However, recent results showed that tumors expressing the most active of these fragments, p95HER2/611CTF, respond to trastuzumab plus chemotherapy. To clarify this discrepancy, we analyzed the response to chemotherapy of cell lines transfected with p95HER2/611CTF and patient-derived xenografts (n = 7 mice per group) with different levels of the fragment. All statistical tests were two-sided. p95HER2/611CTF-negative and positive tumors showed different responses to various chemotherapeutic agents, which are particularly effective on p95HER2/611CTF-positive cells. Furthermore, chemotherapy sensitizes p95HER2/611CTF-positive patient-derived xenograft tumors to trastuzumab (mean tumor volume, trastuzumab alone: 906 mm(3), 95% confidence interval = 1274 to 538 mm(3); trastuzumab+doxorubicin: 259 mm(3), 95% confidence interval = 387 to 131 mm(3); P < .001). This sensitization may be related to HER2 stabilization induced by chemotherapy in p95HER2/611CTF-positive cells.

SUBMITTER: Parra-Palau JL

PROVIDER: S-EPMC4271027 | biostudies-literature | 2014 Nov

REPOSITORIES: biostudies-literature

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Effect of p95HER2/611CTF on the response to trastuzumab and chemotherapy.

Parra-Palau Josep Lluís JL Morancho Beatriz B Peg Vicente V Escorihuela Marta M Scaltriti Maurizio M Vicario Rocio R Zacarias-Fluck Mariano M Pedersen Kim K Pandiella Atanasio A Nuciforo Paolo P Serra Violeta V Cortés Javier J Baselga José J Perou Charles M CM Prat Aleix A Rubio Isabel T IT Arribas Joaquín J

Journal of the National Cancer Institute 20140924 11

Human epidermal growth factor receptor 2 (HER2)-positive breast cancers are currently treated with trastuzumab, an anti-HER2 antibody. About 30% of these tumors express a group of HER2 fragments collectively known as p95HER2. Our previous work indicated that p95HER2-positive tumors are resistant to trastuzumab monotherapy. However, recent results showed that tumors expressing the most active of these fragments, p95HER2/611CTF, respond to trastuzumab plus chemotherapy. To clarify this discrepancy ...[more]

PMID: 25253614

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Project description:Preoperative therapy with chemotherapy and the HER2-targeted monoclonal antibody trastuzumab is valuable for patients with large or locally advanced HER2-positive (HER2+) breast cancers but traditional methods of measuring HER2 expression do not accurately stratify patients for likelihood of response. Quantitative immunofluorescent approaches have the potential to provide a mathematically continuous measure of HER2. Here we seek to determine whether quantitative measurement of HER2 or phospho-HER2 correlates with likelihood of response to trastuzumab- containing neoadjuvant therapy.We evaluated core biopsy samples from 27 HER2+ breast cancer patients enrolled in a preoperative clinical trial using trastuzumab, nab-paclitaxel and carboplatin combination therapy (BrUOG BR-211B (NCT00617942)). Tumor core biopsies were taken before initiation of treatment and 9-13 days after patients received "run-in" doses of either single agent trastuzumab or nab-paclitaxel. The AQUA method of quantitative immunofluorescence was used for analysis of in situ protein expression. Patients then received 18 weeks of treatment, followed by surgery to assess pathologic response to the neoadjuvant regimen.A HER2 score of 2111 by AQUA analysis has been shown to be equivalent to HER2 3+ by immunohistochemical staining in previous studies. Of 20 evaluable patients, 10 cases who achieved a pathologic complete response (pathCR) with neoadjuvant treatment had a mean HER2 level of 10251 compared with 4766 in the patients without pathCR (p?=?0.0021). Measurement of phospho-HER2 showed no difference in pathCR vs non-pathCR groups. In 9 patients who had HER2 levels repeated after a single treatment with trastuzumab there was no evidence of a reduction in the HER2 or phospho-HER2 levels following that exposure.High levels of HER2 are associated with achievement of a pathCR in the preoperative setting, while levels of Phospho-HER2 were not predictive of response. This data suggests that accurate measurement of HER2 may help determine the likelihood of response in the pre-surgical setting. Further validation in larger cohorts is required, but this pilot data shows the feasibility of this approach.

Project description:PurposeRecent data suggest that intrinsic subtype and immune cell infiltration may predict response to trastuzumab-based therapy. We studied the interaction between these factors, changes in immune signatures following brief exposure to trastuzumab, and achievement of pathologic complete response (pCR) to subsequent preoperative trastuzumab and chemotherapy in HER2-positive breast cancer.Experimental designIn patients enrolled on two multicenter trials (03-311 and 211B), tumor core biopsies were obtained at baseline and after brief exposure to single-agent trastuzumab or nab-paclitaxel. Gene expression profiles were assessed to assign PAM50 subtypes, measure immune cell activation, and were correlated with response.ResultsThe pCR rate was significantly higher in HER2-enriched tumors in the Discovery, 03-311 (36%, P = 0.043) dataset, as compared with other subtypes, which validated in 211B (50%, P = 0.048). Significant increases in a signature of immune cell admixture (Immune Index) were observed only following brief exposure to trastuzumab in HER2-enriched tumors (Discovery/03-311, P = 0.05; Validation/211B, P = 0.02). Increased Immune Index was predictive of response after brief exposure (03-311, P = 0.03; 211B, P = 0.04), but not at baseline, in addition to increased expression of a CD4(+) follicular helper T-cell signature (03-311, P = 0.05; 211B, P = 0.04). Brief exposure to trastuzumab significantly increased gene expression of the T-cell marker PD-1 in HER2-enriched tumors (Discovery/03-311, P = 0.045) and PD-1 positivity by IHC (Validation/211B, P = 0.035).ConclusionsCorrelations between pCR rates, increases in Immune Index and markers of T-cell activity following brief exposure to trastuzumab in HER2-enriched tumors provide novel insights into the interaction between tumor biology, antitumor immunity, and response to treatment, and suggest potential clinically useful biomarkers in HER2(+) breast cancers. Clin Cancer Res; 22(13); 3249-59. ©2016 AACR.

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Effect of p95HER2/611CTF on the response to trastuzumab and chemotherapy.

Publications

Effect of p95HER2/611CTF on the response to trastuzumab and chemotherapy.

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