Trastuzumab Has Preferential Activity against Breast Cancers Driven by HER2 Homodimers
01 Mar 2011-Cancer Research (American Association for Cancer Research)-Vol. 71, Iss: 5, pp 1871-1882
TL;DR: The notion that HER2 oligomeric states regulate HER2 signaling is confirmed, also arguing that trastuzumab sensitivity of homodimers may reflect their inability to activate the PI3K (phosphoinositide 3-kinase)/AKT pathway.
Abstract: In breast cancer cells with HER2 gene amplification, HER2 receptors exist on the cell surface as monomers, homodimers, and heterodimers with EGFR/HER3. The therapeutic antibody trastuzumab, an approved therapy for HER2(+) breast cancer, cannot block ligand-induced HER2 heterodimers, suggesting it cannot effectively inhibit HER2 signaling. Hence, HER2 oligomeric states may predict the odds of a clinical response to trastuzumab in HER2-driven tumors. To test this hypothesis, we generated nontransformed human MCF10A mammary epithelial cells stably expressing a chimeric HER2-FKBP molecule that could be conditionally induced to homodimerize by adding the FKBP ligand AP1510, or instead induced to heterodimerize with EGFR or HER3 by adding the heterodimer ligands EGF/TGFα or heregulin. AP1510, EGF, and heregulin each induced growth of MCF10A cells expressing HER2-FKBP. Trastuzumab inhibited homodimer-mediated but not heterodimer-mediated cell growth. In contrast, the HER2 antibody pertuzumab, which blocks HER2 heterodimerization, inhibited growth induced by heregulin but not AP1510. Lastly, the HER2/EGFR tyrosine kinase inhibitor lapatinib blocked both homodimer- and heterodimer-induced growth. AP1510 triggered phosphorylation of Erk1/2 but not AKT, whereas trastuzumab inhibited AP1510-induced Erk1/2 phosphorylation and Shc-HER2 homodimer binding, but not TGFα-induced AKT phosphorylation. Consistent with these observations, high levels of HER2 homodimers correlated with longer time to progression following trastuzumab therapy in a cohort of patients with HER2-overexpressing breast cancer. Together, our findings confirm the notion that HER2 oligomeric states regulate HER2 signaling, also arguing that trastuzumab sensitivity of homodimers may reflect their inability to activate the PI3K (phosphoinositide 3-kinase)/AKT pathway. A clinical implication of our results is that high levels of HER2 homodimers may predict a positive response to trastuzumab.
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Cites background from "Trastuzumab Has Preferential Activi..."
...Although the extracellular segment of ErbB2 lacks a tether nd occurs in an extended conformation, ErbB2 does not form ctive dimers unless it is overexpressed [22]....
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...However, unphysiological overexpression f ErbB2 leads to the formation of a functional homodimer [22]....
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References
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TL;DR: The addition of trastuzumab to chemotherapy was associated with a longer time to disease progression, a higher rate of objective response, a longer duration of response, and a lower rate of death at 1 year.
Abstract: Background The HER2 gene, which encodes the growth factor receptor HER2, is amplified and HER2 is overexpressed in 25 to 30 percent of breast cancers, increasing the aggressiveness of the tumor. Methods We evaluated the efficacy and safety of trastuzumab, a recombinant monoclonal antibody against HER2, in women with metastatic breast cancer that overexpressed HER2. We randomly assigned 234 patients to receive standard chemotherapy alone and 235 patients to receive standard chemotherapy plus trastuzumab. Patients who had not previously received adjuvant (postoperative) therapy with an anthracycline were treated with doxorubicin (or epirubicin in the case of 36 women) and cyclophosphamide with (143 women) or without trastuzumab (138 women). Patients who had previously received adjuvant anthracycline were treated with paclitaxel alone (96 women) or paclitaxel with trastuzumab (92 women). Results The addition of trastuzumab to chemotherapy was associated with a longer time to disease progression (median, 7.4 ...
10,532 citations
"Trastuzumab Has Preferential Activi..." refers background in this paper
...or eventually progress after therapy with trastuzumab (14, 44), thus suggesting the presence of de novo and acquired mechanisms of drug resistance....
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TL;DR: When epidermal growth factor and its relatives bind the ErbB family of receptors, they trigger a rich network of signalling pathways, culminating in responses ranging from cell division to death, motility to adhesion.
Abstract: When epidermal growth factor and its relatives bind the ErbB family of receptors, they trigger a rich network of signalling pathways, culminating in responses ranging from cell division to death, motility to adhesion. The network is often dysregulated in cancer and lends credence to the mantra that molecular understanding yields clinical benefit: over 25,000 women with breast cancer have now been treated with trastuzumab (Herceptin), a recombinant antibody designed to block the receptor ErbB2. Likewise, small-molecule enzyme inhibitors and monoclonal antibodies to ErbB1 are in advanced phases of clinical testing. What can this pathway teach us about translating basic science into clinical use?
6,462 citations
"Trastuzumab Has Preferential Activi..." refers background in this paper
...ErbB receptors are transmembrane tyrosine kinases comprising four members: ErbB1/EGFR, ErbB2/HER2, ErbB3/ HER3, and ErbB4/HER4 (1)....
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TL;DR: Single-agent trastuzumab is active and well tolerated as first-line treatment of women with metastatic breast cancer with HER2 3+ overexpression by IHC or gene amplification by FISH.
Abstract: PURPOSE: To evaluate the efficacy and safety of first-line, single-agent trastuzumab in women with HER2-overexpressing metastatic breast cancer. PATIENTS AND METHODS: One hundred fourteen women with HER2-overexpressing metastatic breast cancer were randomized to receive first-line treatment with trastuzumab 4 mg/kg loading dose, followed by 2 mg/kg weekly, or a higher 8 mg/kg loading dose, followed by 4 mg/kg weekly. RESULTS: The objective response rate was 26% (95% confidence interval [CI], 18.2% to 34.4%), with seven complete and 23 partial responses. Response rates in 111 assessable patients with 3+ and 2+ HER2 overexpression by immunohistochemistry (IHC) were 35% (95% CI, 24.4% to 44.7%) and none (95% CI, 0% to 15.5%), respectively. The clinical benefit rates in assessable patients with 3+ and 2+ HER2 overexpression were 48% and 7%, respectively. The response rates in 108 assessable patients with and without HER2 gene amplification by fluorescence in situ hybridization (FISH) analysis were 34% (95% CI...
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TL;DR: The murine monoclonal antibody mumAb4D5, directed against human epidermal growth factor receptor 2 (p 185HER2), specifically inhibits proliferation of human tumor cells overexpressing p185HER2, but the efficacy of mumAb 4D5 in human cancer therapy is likely to be limited by a human anti-mouse antibody response and lack of effector functions.
Abstract: The murine monoclonal antibody mumAb4D5, directed against human epidermal growth factor receptor 2 (p185HER2), specifically inhibits proliferation of human tumor cells overexpressing p185HER2. However, the efficacy of mumAb4D5 in human cancer therapy is likely to be limited by a human anti-mouse antibody response and lack of effector functions. A "humanized" antibody, humAb4D5-1, containing only the antigen binding loops from mumAb4D5 and human variable region framework residues plus IgG1 constant domains was constructed. Light- and heavy-chain variable regions were simultaneously humanized in one step by "gene conversion mutagenesis" using 311-mer and 361-mer preassembled oligonucleotides, respectively. The humAb4D5-1 variant does not block the proliferation of human breast carcinoma SK-BR-3 cells, which overexpress p185HER2, despite tight antigen binding (Kd = 25 nM). One of seven additional humanized variants designed by molecular modeling (humAb4D5-8) binds the p185HER2 antigen 250-fold and 3-fold more tightly than humAb4D5-1 and mumAb4D5, respectively. In addition, humAb4D5-8 has potency comparable to the murine antibody in blocking SK-BR-3 cell proliferation. Furthermore, humAb4D5-8 is much more efficient in supporting antibody-dependent cellular cytotoxicity against SK-BR-3 cells than mumAb4D5, but it does not efficiently kill WI-38 cells, which express p185HER2 at lower levels.
2,604 citations
TL;DR: A collection of protocols to culture MCF-10A cells, to establish stable pools expressing a gene of interest via retroviral infection, as well as to grow and analyzeMCF- 10A cells in three-dimensional basement membrane culture are provided.
1,957 citations
"Trastuzumab Has Preferential Activi..." refers background or methods in this paper
...liferation, reduction in apoptosis of centrally located cells, disruption of tight junctions and polarity, and induction of acinar expansion without invasion into surrounding matrix (23, 32)....
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...Three-dimensional Matrigel growth assay About 5 10(3) cells/well were seeded in 8-well chamber slides in DMEM/F-12 medium supplemented with cholera toxin, hydrocortisone, insulin and 2% HS on growth factor– reduced Matrigel (BD Biosciences), as described (23)....
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