HSP90 Inhibition Is Effective in Breast Cancer: A Phase II Trial of Tanespimycin (17-AAG) Plus Trastuzumab in Patients with HER2-Positive Metastatic Breast Cancer Progressing on Trastuzumab

Memorial Sloan-Kettering Cancer Center, New York, NY 10065, USA.
Clinical Cancer Research (Impact Factor: 8.72). 05/2011; 17(15):5132-9. DOI: 10.1158/1078-0432.CCR-11-0072
Source: PubMed


HSP90 is a chaperone protein required for the stability of a variety of client proteins. 17-Demethoxygeldanamycin (17-AAG) is a natural product that binds to HSP90 and inhibits its activity, thereby inducing the degradation of these clients. In preclinical studies, HER2 is one of the most sensitive known client proteins of 17-AAG. On the basis of these data and activity in a phase I study, we conducted a phase II study of 17-AAG (tanespimycin) with trastuzumab in advanced trastuzumab-refractory HER2-positive breast cancer.
We enrolled patients with metastatic HER2(+) breast cancer whose disease had previously progressed on trastuzumab. All patients received weekly treatment with tanespimycin at 450 mg/m(2) intravenously and trastuzumab at a conventional dose. Therapy was continued until disease progression. The primary endpoint was response rate by Response Evaluation Criteria in Solid Tumors (RECIST) criteria.
Thirty-one patients were enrolled with a median age of 53 years and a median Karnofsky performance status (KPS) of 90%. The most common toxicities, largely grade 1, were diarrhea, fatigue, nausea, and headache. The overall response rate was 22%, the clinical benefit rate [complete response + partial response + stable disease] was 59%, the median progression-free survival was 6 months (95% CI: 4-9), and the median overall survival was 17 months (95% CI: 16-28).
This is the first phase II study to definitively show RECIST-defined responses for 17-AAG in solid tumors. Tanespimycin plus trastuzumab has significant anticancer activity in patients with HER2-positive, metastatic breast cancer previously progressing on trastuzumab. Further research exploring this therapeutic interaction and the activity of HSP90 inhibitors is clearly warranted.

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    • "e l s e v i e r . c o m / l o c a t e / i j p h a r m to their use (Usmani et al., 2009; Pacey et al., 2012; Modi et al., 2011). For example, 17-AAG, which has reached clinical trials alone or in combination with other drugs, shows a very promising anticancer effect but also provokes severe nephrotoxicity and is difficult to formulate because of its poor water solubility. "
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    ABSTRACT: 6BrCaQ is a promising anti-cancer agent derived from novobiocin, which has been shown to inhibit Hsp90. 6BrCaQ was loaded into nanometer-scaled phospholipid vesicles (liposomes) suitable for drug delivery to solid tumors. The effective incorporation of the drug within the phospholipid bilayer was investigated by differential scanning calorimetry. Liposomal 6BrCaQ showed good activity on PC-3 cell lines in vitro in terms of apoptosis induction and cell growth arrest in G2/M. Liposomes containing 6BrCaQ were also shown to slow down migration of PC-3 cells in presence of chemokine ligand 2 and to synergize with doxorubicin. Several Hsp90 targeting molecules like geldanamycin induce accumulation of Hsp70, leading to cytoprotection and often correlated with poor prognosis. In this study, we did not report any Hsp70 induction after treatment with liposomal 6BrCaQ but a decrease in Hsp90 and CDK-4 protein expression, indicating an effect on the chaperon machinery. Liposomal encapsulation of 6BrCaQ revealed promising anti-cancer effects and a better understanding of its mechanism of action.
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    • "Heat shock protein 90 (Hsp90) is a molecular chaperone whose association is required for the stability and function of numerous oncoproteins that promote the growth and/or survival of cancer cells, and therefore may serve as a therapeutic target for the treatment of cancer [1] . Several Hsp90 inhibitors such as 17-allylamino- 17-demethoxy-geldanamycin (17-AAG), an ansamycin Hsp90 inhibitor, and NVP-AUY922 (hereafter called AUY922), a non-ansamycin Hsp90 inhibitor, have shown potent antitumor activity in a wide-range of malignancies2345. However, it is known that treatment with Hsp90 inhibitors leads, through a negative feedback loop, to activation of the heat shock factor (HSF1), which causes transcriptional induction of Hsp70/Hsp27 that protect cancer cells from apoptosis and induce drug resistance [6, 7], offsetting their own anticancer activities. "
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    ABSTRACT: The effectiveness of Hsp90 inhibitors as anticancer agents was limited in multidrug-resistant (MDR) human cancer cells due to induction of heat shock proteins (Hsps) such as Hsp70/Hsp27 and P-glycoprotein (P-gp)-mediated efflux. In the present study, we showed that resistance to Hsp90 inhibitors of MDR human cancer cells could be overcome with SIRT1 inhibition. SIRT1 knock-down or SIRT1 inhibitors (amurensin G and EX527) effectively suppressed the resistance to Hsp90 inhibitors (17-AAG and AUY922) in several MDR variants of human lymphoblastic leukemia and human breast cancer cell lines. SIRT1 inhibition down-regulated the expression of heat shock factor 1 (HSF1) and subsequently Hsps and facilitated Hsp90 multichaperone complex disruption via hyperacetylation of Hsp90/Hsp70. These findings were followed by acceleration of ubiquitin ligase CHIP-mediated mutant p53 (mut p53) degradation and subsequent down-regulation of P-gp in 17-AAG-treated MDR cancer cells expressing P-gp and mut p53 after inhibition of SIRT1. Therefore, combined treatment with Hsp90 inhibitor and SIRT1 inhibitor could be a more effective therapeutic approach for Hsp90 inhibitor-resistant MDR cells via down-regulation of HSF1/Hsps, mut p53 and P-gp.
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    • "Since numerous oncoproteins have been identified as HSP90 clients, the inhibition of Hsp90 functions affects multiple oncogenic substrates simultaneously and represents an appealing molecular target for combination drug therapy [17]. In a recently completed phase II study of 17-AAG and trastuzumab, an overall clinical benefit (including stable disease) was seen in 57% of the patients with ErbB2-positive metastatic breast cancer progressing on trastuzumab [13]. It has also been reported that the inhibition of Hsp90 with 17-AAG sensitizes different cancer cell lines to DNA damage response mediated cellular senescence [18]. "
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    ABSTRACT: ErbB2-driven breast cancers constitute 20-25% of the cases diagnosed within the USA. The humanized anti-ErbB2 monoclonal antibody, Trastuzumab (Herceptin™; Genentech), with chemotherapy is the current standard of treatment. Novel agents and strategies continue to be explored, given the challenges posed by Trastuzumab-resistance development in most patients. The HSP90 inhibitor, 17-allylaminodemethoxygeldanamycin (17-AAG), which induces ErbB2 degradation and attenuates downstream oncogenic signaling, is one such agent that showed significant promise in early phase I and II clinical trials. Its low water solubility, potential toxicities and undesirable side effects observed in patients, partly due to the Cremophor-based formulation, have been discouraging factors in the advancement of this promising drug into clinical use. Encapsulation of 17-AAG into polymeric nanoparticle formulations, particularly in synergistic combination with conventional chemotherapeutics, represents an alternative approach to overcome these problems. Herein, we report an efficient co-encapsulation of 17-AAG and doxorubicin, a clinically well-established and effective modality in breast cancer treatment, into biodegradable and biocompatible polypeptide-based nanogels. Dual drug-loaded nanogels displayed potent cytotoxicity in a breast cancer cell panel and exerted selective synergistic anticancer activity against ErbB2-overexpressing breast cancer cell lines. Analysis of ErbB2 degradation confirmed efficient 17-AAG release from nanogels with activity comparable to free 17-AAG. Furthermore, nanogels containing both 17-AAG and doxorubicin exhibited superior antitumor efficacy in vivo in an ErbB2-driven xenograft model compared to the combination of free drugs. These studies demonstrate that polypeptide-based nanogels can serve as novel nanocarriers for encapsulating 17-AAG along with other chemotherapeutics, providing an opportunity to overcome solubility issues and thereby exploit its full potential as an anti-cancer agent. Copyright © 2015. Published by Elsevier B.V.
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