Heat shock protein 90 (Hsp90) inhibitor STA-9090 (Ganetespib) ameliorates inflammation in a mouse model of atopic dermatitis

Molecular chaperones belonging to the heat shock protein 90 (Hsp90) family are implicated in inflammatory processes and described as potential novel therapeutic targets in autoimmune/inflammatory skin diseases. While the pathological role of circulating Hsp90 has been recently proposed in patients with atopic dermatitis (AD), a chronic inflammatory skin disease characterized by intense itching and recurrent skin lesions, studies aimed at investigating the role of Hsp90 as a potential target of AD therapy have not yet been conducted. Here, the effects of the Hsp90 blocker STA-9090 (Ganetespib) applied systemically or topically were determined in an experimental mouse model of dinitrochlorobenzene (DNCB)-induced AD. Intraperitoneal administration of STA-9090 ameliorated clinical disease severity, histological epidermal thickness, and dermal leukocyte infiltration in AD mice which was associated with reducing the scratching behavior in DNCB-treated animals. Additionally, topically applied STA-9090 led to lowered disease activity in AD mice, reduced serum levels of IgE, and up-regulated filaggrin expression in lesional skin samples. Our observations suggest that Hsp90 may be a promising therapeutic target in atopic dermatitis and potentially other inflammatory or autoimmune dermatoses.

Extracellular Hsp90 Binds to and Aligns Collagen-1 to Enhance Breast Cancer Cell Invasiveness

Cancer cell-secreted eHsp90 binds and activates proteins in the tumor microenvironment crucial in cancer invasion. Therefore, targeting eHsp90 could inhibit invasion, preventing metastasis-the leading cause of cancer-related mortality. Previous eHsp90 studies have solely focused on its role in cancer invasion through the 2D basement membrane (BM), a form of extracellular matrix (ECM) that lines the epithelial compartment. However, its role in cancer invasion through the 3D Interstitial Matrix (IM), an ECM beyond the BM, remains unexplored. Using a Collagen-1 binding assay and second harmonic generation (SHG) imaging, we demonstrate that eHsp90 directly binds and aligns Collagen-1 fibers, the primary component of IM. Furthermore, we show that eHsp90 enhances Collagen-1 invasion of breast cancer cells in the Transwell assay. Using Hsp90 conformation mutants and inhibitors, we established that the Hsp90 dimer binds to Collagen-1 via its N-domain. We also demonstrated that while Collagen-1 binding and alignment are not influenced by Hsp90's ATPase activity attributed to the N-domain, its open conformation is crucial for increasing Collagen-1 alignment and promoting breast cancer cell invasion. These findings unveil a novel role for eHsp90 in invasion through the IM and offer valuable mechanistic insights into potential therapeutic approaches for inhibiting Hsp90 to suppress invasion and metastasis.

Ganetespib (STA-9090) augments sorafenib efficacy via necroptosis induction in hepatocellular carcinoma: Implications from preclinical data for a novel therapeutic approach

Sorafenib, a multikinase inhibitor, is a first-line treatment for advanced hepatocellular carcinoma, but its long-term effectiveness is limited by the emergence of resistance mechanisms. One such mechanism is the reduction of microvessel density and intratumoral hypoxia caused by prolonged sorafenib treatment. Our research has demonstrated that HSP90 plays a critical role in conferring resistance to sorafenib in HepG2 cells under hypoxic conditions and N-Nitrosodiethylamine-exposed mice as well. This occurs through the inhibition of necroptosis on the one hand and the stabilization of HIF-1α on the other hand. To augment the effects of sorafenib, we investigated the use of ganetespib, an HSP90 inhibitor. We found that ganetespib activated necroptosis and destabilized HIF-1α under hypoxia, thus enhancing the effectiveness of sorafenib. Additionally, we discovered that LAMP2 aids in the degradation of MLKL, which is the mediator of necroptosis, through the chaperone-mediated autophagy pathway. Interestingly, we observed a significant negative correlation between LAMP2 and MLKL. These effects resulted in a reduction in the number of surface nodules and liver index, indicating a regression in tumor production rates in mice with HCC. Furthermore, AFP levels decreased. Combining ganetespib with sorafenib showed a synergistic cytotoxic effect and resulted in the accumulation of p62 and inhibition of macroautophagy. These findings suggest that the combined therapy of ganetespib and sorafenib may offer a promising approach for the treatment of hepatocellular carcinoma by activating necroptosis, inhibiting macroautophagy, and exhibiting a potential antiangiogenic effect. Overall, continued research is critical to establish the full therapeutic potential of this combination therapy.

Overcoming acquired resistance to HSP90 inhibition by targeting JAK-STAT signalling in triple-negative breast cancer

Background

Due to the lack of effective therapies and poor prognosis in TNBC (triple-negative breast cancer) patients, there is a strong need to develop effective novel targeted therapies for this subtype of breast cancer. Inhibition of heat shock protein 90 (HSP90), a conserved molecular chaperone that is involved in the regulation of oncogenic client proteins, has shown to be a promising therapeutic approach for TNBC. However, both intrinsic and acquired resistance to HSP90 inhibitors (HSP90i) limits their effectiveness in cancer patients.

Methods

We developed models of acquired resistance to HSP90i by prolonged exposure of TNBC cells to HSP90i (ganetespib) in vitro. Whole transcriptome profiling and a 328-compound bioactive small molecule screen were performed on these cells to identify the molecular basis of acquired resistance to HSP90i and potential therapeutic approaches to overcome resistance.

Results

Among a panel of seven TNBC cell lines, the most sensitive cell line (Hs578T) to HSP90i was selected as an in vitro model to investigate acquired resistance to HSP90i. Two independent HSP90i-resistant clones were successfully isolated which both showed absence of client proteins degradation, apoptosis induction and G2/M cell cycle arrest after treatment with HSP90i. Gene expression profiling and pathway enrichment analysis demonstrate significant activation of the survival JAK-STAT signalling pathway in both HSP90i-resistant clones, possibly through IL6 autocrine signalling. A bioactive small molecule screen also demonstrated that the HSP90i-resistant clones showed selective sensitivity to JAK2 inhibition. Inhibition of JAK and HSP90 caused higher induction of apoptosis, despite prior acquired resistance to HSP90i.

Conclusions

Acquired resistance to HSP90i in TNBC cells is associated with an upregulated JAK-STAT signalling pathway. A combined inhibition of the JAK-STAT signalling pathway and HSP90 could overcome this resistance. The benefits of the combined therapy could be explored further for the development of effective targeted therapy in TNBC patients.

Electronic supplementary material

The online version of this article (10.1186/s12885-019-5295-z) contains supplementary material, which is available to authorized users.

Inhibition of HSP90β by ganetespib blocks the microglial signalling of evoked pro-inflammatory responses to heat shock

Although microglial reaction to heat shock is considered to be protective, heat shock is still a potential hazard caused by high temperatures. Recent studies indicate that the inhibition of the 90-kDa heat shock protein (HSP90) increasing the protective heat shock response and suppressing inflammatory signalling pathways in several diseases. Nevertheless, the effects of heat shock on microglial pro-inflammatory responses are not completely identical. Here, we aim to investigate the effect of the HSP90 inhibitor ganetespib on microglial pro-inflammatory responses following heat shock. HSP90 isoforms were determined by transfecting N9 microglial cells (N9 cells) with enzymatically prepared siRNA (esiRNAs). We found that heat shock significantly increased the secretion of tumour necrosis factor alpha (TNF-α), interleukin (IL)-1β, IL-6 and nitric oxide (NO), and the phosphorylation of extracellular signal-regulated kinase (ERK), Janus-activated kinase 2 (JAK2), signal transducer and activator of transcription 3 (STAT3), nuclear factor of kappa light polypeptide gene enhancer in B-cells inhibitor alpha (IκB-α) and p65 nuclear factor kappa-light-chain-enhancer of activated B cells (p65 NF-κB) in N9 cells. These increases, except for phospho-p65, were attenuated efficiently in a dose-dependent manner by ganetespib pretreatment. Furthermore, the suppression of heat shock-evoked cytokines and NO production, and the phosphorylation of ERK, JAK2 and STAT3 in cytosols and/or nuclei were also observed by administering esiRNA HSP90β, but not HSP90α, in heat shock-treated N9 cells. Taken together, our findings demonstrate that the HSP90 inhibitor ganetespib blocks pro-inflammatory responses in heat shock-treated N9 cells via a signalling mechanism involving HSP90β and STAT3.

Ganetespib radiosensitization for liver cancer therapy

Therapies for liver cancer particularly those including radiation are still inadequate. Inhibiting the stress response machinery is an appealing anti-cancer and radiosensitizing therapeutic strategy. Heat-shock-protein-90 (HSP90) is a molecular chaperone that is a prominent effector of the stress response machinery and is overexpressed in liver cancer cells. HSP90 client proteins include critical components of pathways implicated in liver cancer cell survival and radioresistance. The effects of a novel non-geldanamycin HSP90 inhibitor, ganetespib, combined with radiation were examined on 3 liver cancer cell lines, Hep3b, HepG2 and HUH7, using in vitro assays for clonogenic survival, apoptosis, cell cycle distribution, γH2AX foci kinetics and client protein expression in pathways important for liver cancer survival and radioresistance. We then evaluated tumor growth delay and effects of the combined ganetespib-radiation treatment on tumor cell proliferation in a HepG2 hind-flank tumor graft model. Nanomolar levels of ganetespib alone exhibited liver cancer cell anti-cancer activity in vitro as shown by decreased clonogenic survival that was associated with increased apoptotic cell death, prominent G2-M arrest and marked changes in PI3K/AKT/mTOR and RAS/MAPK client protein activity. Ganetespib caused a supra-additive radiosensitization in all liver cancer cell lines at low nanomolar doses with enhancement ratios between 1.33–1.78. These results were confirmed in vivo, where the ganetespib-radiation combination therapy produced supra-additive tumor growth delay compared with either therapy by itself in HepG2 tumor grafts. Our data suggest that combined ganetespib-radiation therapy exhibits promising activity against liver cancer cells, which should be investigated in clinical studies.

Epigenetic effects of inhibition of heat shock protein 90 (HSP90) in human pancreatic and colon cancer

Silencing of tumor suppressor and DNA repair genes through methylation plays a role in cancer development, growth and response to therapy in colorectal and pancreatic cancers. Heat shock protein 90 (HSP90) regulates transcription of DNA methyltransferase enzymes (DNMT). In addition, DNMTs are client proteins of HSP90. The aim of this study is to evaluate the effects of HSP90 inhibition on DNA methylation in colorectal and pancreatic cancer cell lines. Our data shows that inhibition of HSP90 using ganetespib resulted in downregulation of mRNA and protein expression of DNMT1, DNMT3A, and DNMT3B in HT-29 and MIA PaCa-2 cell lines. This in turn was associated with a drop in the fraction of methylated cytosine residues and re-expression of silenced genes including MLH-1, P16 and SPARC. These effects were validated in HT-29 tumors implanted subcutaneously in mice following in vivo administration of ganetespib. This work demonstrates the effectiveness of ganetespib, an HSP90 inhibitor in modulating DNA methylation through downregulation of DNMT expression.

A phase I trial of ganetespib in combination with paclitaxel and trastuzumab in patients with human epidermal growth factor receptor-2 (HER2)-positive metastatic breast cancer

BACKGROUND

Targeted therapies in HER2-positive metastatic breast cancer significantly improve outcomes but efficacy is limited by therapeutic resistance. HER2 is an acutely sensitive Heat Shock Protein 90 (HSP90) client and HSP90 inhibition can overcome trastuzumab resistance. Preclinical data suggest that HSP90 inhibition is synergistic with taxanes with the potential for significant clinical activity. We therefore tested ganetespib, a HSP90 inhibitor, in combination with paclitaxel and trastuzumab in patients with trastuzumab-refractory HER2-positive metastatic breast cancer.

METHODS

In this phase I dose-escalation study, patients with trastuzumab-resistant HER2-positive metastatic breast cancer received weekly trastuzumab (2 mg/kg) and paclitaxel (80 mg/m²) on days 1, 8, 15, and 22 of a 28-day cycle with escalating doses of ganetespib (100 mg/m², 150 mg/m², and a third cohort of 125 mg/m² if needed) on days 1, 8, and 15. Therapy was continued until disease progression or toxicity. The primary objective was to establish the safety and maximum tolerated dose and/or recommended phase II dose (RP2D) of this therapy. The secondary objectives included evaluation of the effects of ganetespib on the pharmacokinetics of paclitaxel, and to make a preliminary assessment of the efficacy of the combination therapy.

RESULTS

Dose escalation was completed for the two main cohorts without any observed dose-limiting toxicities. Nine patients received treatment. The median prior lines of anti-HER2 therapy numbered three (range 2-4), including prior pertuzumab in 9/9 patients and ado-trastuzumab emtansine (T-DM1) in 8/9 patients. The most common grade 1/2 adverse events (AEs) were diarrhea, fatigue, anemia, and rash. There were no grade 4 AEs related to ganetespib. The overall response rate was 22% (2/9 patients had partial response) and stable disease was seen in 56% (5/9 patients). The clinical benefit rate was 44% (4/9 patients). The median progression-free survival was 20 weeks (range 8-55).

CONCLUSION

The RP2D of ganetespib is 150 mg/m² in combination with weekly paclitaxel plus trastuzumab. The combination was safe and well tolerated. Despite prior taxanes, pertuzumab, and T-DM1, clinical activity of this triplet regimen in this heavily pretreated cohort is promising and warrants further study in HER2-positive metastatic breast cancer.

TRIAL REGISTRATION

ClinicalTrials.gov NCT02060253 . Registered 30 January 2014.

Ganetespib, an HSP90 inhibitor, kills Epstein-Barr virus (EBV)-infected B and T cells and reduces the percentage of EBV-infected cells in the blood

HSP90 inhibitors have been shown to kill Epstein-Barr virus (EBV)-infected cells by reducing the level of EBV EBNA-1 and/or LMP1. We treated virus-infected cells with ganetespib, an HSP90 inhibitor currently being evaluated in multiple clinical trials for cancer and found that the drug killed EBV-positive B and T cells and reduced the level of both EBV EBNA-1 and LMP1. Treatment of cells with ganetespib also reduced the level of pAkt. Ganetespib delayed the onset of EBV-positive lymphomas and prolonged survival in SCID mice inoculated with one EBV-transformed B-cell line, but not another B-cell line. The former cell line showed lower levels of EBNA-1 after treatment with ganetespib in vitro. Treatment of a patient with T-cell chronic active EBV with ganetespib reduced the percentage of EBV-positive cells in the peripheral blood. These data indicate that HSP90 inhibitors may have a role in the therapy of certain EBV-associated diseases.

Targeting the Janus-activated kinase-2-STAT3 signalling pathway in pancreatic cancer using the HSP90 inhibitor ganetespib

BACKGROUND

Pancreatic cancer (PC) is an aggressive malignancy characterised by chemoresistance. HSP90 is important for stabilisation of proteins, cell signalling and malignant growth. We hypothesised that ganetespib, an HSP90 inhibitor, can inhibit PC cell growth by interfering with multiple signalling cascades, including the Janus-activated kinase (JAK)-STAT pathway, and act synergistically with chemotherapeutic drugs.

METHODS

The effects of ganetespib were evaluated in ASPC-1, HPAC, MIA PaCA-2 and PANC-1 cell lines using a cell proliferation assay. Effects on the expression of phosphoinositide 3-kinase (PI3K)/AKT, mitogen-activated protein kinase (MAPK) and JAK-STAT pathways were examined by Western blot. JAK2 and STAT3 were knocked down by transient transfection with JAK2 or STAT3 small interfering RNA. ASPC-1 and HPAC cell lines were tested for sensitivity to ganetespib, 5-fluorouracil/oxaliplatin, and gemcitabine/paclitaxel, alone and in combination, using an in vivo tumour xenograft model.

RESULTS

Ganetespib significantly decreased cell proliferation in all tested PC cell lines. Ganetespib decreased the activation of extracellular signal-related kinase (ERK), PI3K/AKT, and c-Jun NH2-terminal kinase (JNK) signalling molecules and diminished the activation of STAT3 in an additive manner with isolated downregulation of JAK2 expression. In animal models, ganetespib potentiated the effects of 5-fluouracil/oxaliplatin and gemcitabine/paclitaxel, as measured by tumour volume. Western blot analysis from tumours removed from animals confirmed the effects of ganetespib on PI3K/AKT, ERK and JNK pathways.

CONCLUSIONS

Ganetespib inhibits the growth of PC cells, an effect associated with downregulation of signalling through the JAK2-STAT3, PI3K/AKT and MAPK pathways. This provides preclinical proof-of-principle that ganetespib enhances the activity of chemotherapeutic agents and warrants further evaluation in PC clinical trials.

A phase II trial of ganetespib, a heat shock protein 90 Hsp90) inhibitor, in patients with docetaxel-pretreated metastatic castrate-resistant prostate cancer (CRPC)-a prostate cancer clinical trials consortium (PCCTC) study

INTRODUCTION

Heat shock protein 90 (Hsp90) has been studied as a therapeutic target in many cancers. In preclinical trials, the Hsp90 ATPase inhibitor ganetespib demonstrated potent inhibition of solid tumor growth, with superior potency than prior Hsp90 inhibitors. Given the promising preclinical outcome and favorable pharmacologic properties of ganetespib, we conducted a phase II trial of single-agent ganetespib in patients with metastatic, castrate-resistant prostate cancer (mCRPC). The primary objective of the study was to determine the 6-month progression-free survival (PFS) rate.

METHODS

Patients with mCRPC who had been previously treated with docetaxel were enrolled after meeting eligibility criteria. All patients received ganetespib at 200 mg/m(2) on days 1, 8, and 15 of every 28 days (one cycle). Subjects who tolerated therapy were continued on ganetespib until disease progression. Considering that Hsp90 acetylation may confer insensitivity to Hsp90 inhibitors and maspin inhibits protein deacetylation, maspin-associated molecular markers were evaluated.

RESULTS

Eighteen patients were recruited into the trial; most were Caucasian, had performance status 1, had received prior docetaxel, and were heavily pretreated. Of the 17 patients who were treated, none attained 6-month PFS. Only 2 patients achieved PFS > 4 months. The median PFS was 1.9 months. As per the study design, the trial was terminated after the interim analysis. The most frequent types of Grade 3 toxicity were dehydration, diarrhea, and fatigue. Molecular markers provided little additional insight regarding drug activity.

CONCLUSIONS

Ganetespib demonstrated minimal clinical activity in men with mCRPC. The true 6-month PFS rate was, at most, 0.20. Possible reasons for this include selection of a heavily pretreated patient population and lack of agent potency in patients with mCRPC.

The HSP90 inhibitor ganetespib: A potential effective agent for Acute Myeloid Leukemia in combination with cytarabine

HSP90 is a multi-client chaperone involved in regulating a large array of cellular processes and is commonly overexpressed in many different cancer types including hematological malignancies. Inhibition of HSP90 holds promise for targeting multiple molecular abnormalities and is therefore an attractive target for heterogeneous malignancies such as Acute Myeloid Leukemia (AML). Ganetespib is a highly potent second generation HSP90 inhibitor which we show is significantly more effective against primary AML blasts at nanomolar concentrations when compared with cytarabine (p<0.001). Dose dependant cytotoxicity was observed with an apoptotic response coordinate with the loss of pro-survival signaling through the client protein AKT. Combination treatment of primary blasts with ganetespib and cytarabine showed good synergistic interaction (combination index (CI): 0.47) across a range of drug effects with associated reduction in HSP70 feedback and AKT signaling levels. In summary, we show ganetespib to have high activity in primary AMLs as a monotherapy and a synergistic relationship with cytarabine when combined. The combination of cytotoxic cell death, suppression of cytoprotective/drug resistance mechanisms such as AKT and reduced clinical toxicity compared to other HSP90 inhibitors provide strong rationale for the clinical assessment of ganetespib in AML.

Ganetespib, a novel Hsp90 inhibitor in patients with KRAS mutated and wild type, refractory metastatic colorectal cancer

BACKGROUND

Heat shock protein 90 (Hsp90) is a cellular chaperone that is required for the maturation and stability of a variety of proteins that play key roles in colon cancer initiation and progression. The primary objective of the current study was to define the safety and efficacy of ganetespib, a novel, selective small-molecule Hsp90 inhibitor, in patients with refractory metastatic colorectal cancer.

PATIENTS AND METHODS

The study was a single-arm, Simon 2-stage, phase II trial for patients with chemotherapy-refractory, metastatic colorectal cancer. Patients received ganetespib 200 mg/m(2) intravenously. Tumor tissue was collected before treatment and 48 hours after treatment for changes in expression of Hsp90 client proteins and other potential pharmacodynamics markers. V-Ki-ras2 Kirsten rat sarcoma viral oncogene homolog (KRAS), v-Raf murine sarcoma viral oncogene homolog B, and phosphatidylinositol-4, 5-bisphosphate 3-kinase, catalytic subunit alpha (PIK3CA) mutational status was also determined.

RESULTS

Seventeen patients were treated (median age, 58; range, 44-79 years). No patients demonstrated objective regression of disease. Two patients had stable disease of 6.8 and 5.1 months duration. Serious adverse events that were potentially attributable to ganetespib included diarrhea (12%, n = 2), fatigue (17%, n = 3), and increased aspartate aminotransferase/alanine aminotransferase (12%, n = 2) and alkaline phosphatase (6%, n = 1) levels. Of the 17 evaluable patients, 9 (53%) including patients with stable disease as best response, had KRAS-mutant tumors.

CONCLUSION

In this first phase II investigation of an Hsp90 inhibitor in colorectal cancer, ganetespib as a single agent did not demonstrate activity in chemotherapy-refractory metastatic colorectal cancer. However, on the basis of the drug's promising preclinical combination data and the relatively mild toxicity profile, further clinical investigation of this agent in combination with standard cytotoxic agents is planned.

A phase II open-label study of ganetespib, a novel heat shock protein 90 inhibitor for patients with metastatic breast cancer

BACKGROUND

Ganetespib is a small molecule, nongeldanamycin HSP90 inhibitor with potent inhibitory effects on HSP90-dependent oncoproteins of relevance to breast cancer pathogenesis. We therefore tested ganetespib in an unselected cohort of patients with MBC.

PATIENTS AND METHODS

Patients were treated with single agent ganetespib at 200 mg/m(2) once weekly for 3 weeks, on a 28-day cycle. Therapy was continued until disease progression. The primary end point was ORR using Reponse Evaluation Criteria in Solid Tumors version 1.1.

RESULTS

Twenty-two patients were enrolled with a median age of 51(range, 38-70) years and a median Eastern Cooperative Oncology Group performance status of 0 (range, 0-1). Most patients had at least 2 previous lines of chemotherapy in the metastatic setting. Most common toxicities, largely grade 1/2, were diarrhea, fatigue, nausea, and hypersensitivity reaction. The ORR in this unselected population was 9%, with all responses coming from the subset of patients with HER2-positive MBC (2/13; 15%). One patient with TNBC had objective tumor regression in the lung metastases. The clinical benefit rate (complete response + partial response + stable disease > 6 months) was 9%, median progression-free survival was 7 weeks (95% confidence interval [CI], 7-19), and median overall survival was 46 weeks (95% CI, 27-not applicable).

CONCLUSION

The study did not meet the prespecified criteria for ORR in the first stage of the Simon 2-stage model in this heavily pretreated unselected population of MBC. However, activity was observed in trastuzumab-refractory HER2-positive and TNBC. Ganetespib was well tolerated and responses in more targeted populations harboring specific HSP90-dependent oncoproteins justifies its further study, particularly as part of rational combinations.