HSP90 Inhibitor SNX5422/2112 Targets the Dysregulated Signal and Transcription Factor Network and Malignant Phenotype of Head and Neck Squamous Cell Carcinoma

DRN-CDR: A cancer drug response prediction model using multi-omics and drug features

Cancer drug response (CDR) prediction is an important area of research that aims to personalize cancer therapy, optimizing treatment plans for maximum effectiveness while minimizing potential negative effects. Despite the advancements in Deep learning techniques, the effective integration of multi-omics data for drug response prediction remains challenging. In this paper, a regression method using Deep ResNet for CDR (DRN-CDR) prediction is proposed. We aim to explore the potential of considering sole cancer genes in drug response prediction. Here the multi-omics data such as gene expressions, mutation data, and methylation data along with the molecular structural information of drugs were integrated to predict the IC50 values of drugs. Drug features are extracted by employing a Uniform Graph Convolution Network, while Cell line features are extracted using a combination of Convolutional Neural Network and Fully Connected Networks. These features are then concatenated and fed into a deep ResNet for the prediction of IC50 values between Drug - Cell line pairs. The proposed method yielded higher Pearson's correlation coefficient (rp) of 0.7938 with lowest Root Mean Squared Error (RMSE) value of 0.92 when compared with similar methods of tCNNS, MOLI, DeepCDR, TGSA, NIHGCN, DeepTTA, GraTransDRP and TSGCNN. Further, when the model is extended to a classification problem to categorize drugs as sensitive or resistant, we achieved AUC and AUPR measures of 0.7623 and 0.7691, respectively. The drugs such as Tivozanib, SNX-2112, CGP-60474, PHA-665752, Foretinib etc., exhibited low median IC50 values and were found to be effective anti-cancer drugs. The case studies with different TCGA cancer types also revealed the effectiveness of SNX-2112, CGP-60474, Foretinib, Cisplatin, Vinblastine etc. This consistent pattern strongly suggests the effectiveness of the model in predicting CDR.

Combination therapy involving HSP90 inhibitors for combating cancer: an overview of clinical and preclinical progress

The molecular chaperone heat shock protein 90 (HSP90) regulates multiple crucial signalling pathways in cancer by driving the maturation of key signalling components, thereby playing a crucial role in tumorigenesis and drug resistance in cancer. Inhibition of HSP90 results in metastable conformational collapse of its client proteins and their proteasomal degradation. Considerable efforts have been devoted to the development of small-molecule inhibitors targeting HSP90, and more than 20 inhibitors have been evaluated in clinical trials for cancer therapy. However, owing to disadvantages such as organ toxicity and drug resistance, only one HSP90 inhibitor has been approved for use in clinical settings. In recent years, HSP90 inhibitors used in combination with other anti-cancer therapies have shown remarkable potential in the treatment of cancer. HSP90 inhibitors work synergistically with various anti-cancer therapies, including chemotherapy, targeted therapy, radiation therapy and immunotherapy. HSP90 inhibitors can improve the pharmacological effects of the above-mentioned therapies and reduce treatment resistance. This review provides an overview of the use of combination therapy with HSP90 inhibitors and other anti-cancer therapies in clinical and preclinical studies reported in the past decade and summarises design strategies and prospects for these combination therapies. Altogether, this review provides a theoretical basis for further research and application of these combination therapies in the treatment of cancer.

The multifaceted role of STAT3 pathway and its implication as a potential therapeutic target in oral cancer

Oral cancer is one of the leading causes of cancer-related deaths, and it has become a matter of serious concern due to the alarming rise in its incidence rate worldwide. Despite recent advancements in oral cancer treatment strategies, there are no significant improvements in patient's survival rate. Among the numerous cell signaling pathways involved in oral cancer development and progression, STAT3 is known to play a multifaceted oncogenic role in shaping the tumor pathophysiology. STAT3 hyperactivation in oral cancer contributes to survival, proliferation, invasion, epithelial to mesenchymal transition, metastasis, immunosuppression, chemoresistance, and poor prognosis. A plethora of pre-clinical and clinical studies have documented the role of STAT3 in the initiation and development of oral cancer and showed that STAT3 inhibition holds significant potential in the prevention and treatment of this cancer. However, to date, targeting STAT3 activation mainly involves inhibiting the upstream signaling molecules such as JAK and IL-6 receptors. The major challenge in targeting STAT3 lies in the complexity of its phosphorylation- and dimerization-independent functions, which are not affected by disrupting the upstream regulators. The present review delineates the significance of the STAT3 pathway in regulating various hallmarks of oral cancer. In addition, it highlights the STAT3 inhibitors identified to date through various preclinical and clinical studies that can be employed for the therapeutic intervention in oral cancer treatment.

Opioid Antagonist Nanodrugs Successfully Attenuate the Severity of Ischemic Stroke

The United States is in the midst of an opioid epidemic that is linked to a number of serious health issues, including an increase in cerebrovascular events, namely, stroke. Chronic prescription opioid use exacerbates the risk and severity of ischemic stroke, contributing to stroke as the fifth overall cause of death in the United States and costing the US health care system over $30 billion annually. Pathologically, opioids challenge the integrity of the blood–brain barrier (BBB), resulting in a dysregulation of tight junction (TJ) proteins that are crucial in maintaining barrier homeostasis. Despite this, treatment options for ischemic stroke are limited, and there are no pharmacological options to attenuate TJ damage, including in incidents that are linked to opioid use. Herein, we have generated carrier-free, pure “nanodrugs” or nanoparticles of naloxone and naltrexone with enhanced therapeutic properties compared to the original (parent) drugs. The generated nanoformulations of both opioid antagonists exhibited successful attenuation of morphine- or oxycodone-induced alterations of TJ protein expression and reduced oxidative stress to a greater extent than the parent drugs (non-nano). As a proof of concept, we then proceeded to evaluate the therapeutic effectiveness of the generated nanodrugs in an ischemic stroke model of mice exposed to morphine or oxycodone. Our results demonstrate that the opioid antagonist nanoformulations reduced stroke severity in mice. Overall, this research implements advances in nanotechnology-based repurposing of FDA-approved therapeutics, and the obtained results also suggest underlying pharmacological mechanisms of opioid antagonists, further supporting these opioid antagonists and their respective nanoformulations as potential therapeutic agents for ischemic stroke.

Targeting HSP90 Inhibits Proliferation and Induces Apoptosis Through AKT1/ERK Pathway in Lung Cancer

Lung cancer is one of the most common malignant cancers worldwide. Searching for specific cancer targets and developing efficient therapies with lower toxicity is urgently needed. HPS90 is a key chaperon protein that has multiple client proteins involved in the development of cancer. In this study, we investigated the transcriptional levels of HSP90 isoforms in cancerous and normal tissues of lung cancer patients in multiple datasets. The higher expression of HSP90AA1 in cancer tissues correlated with poorer overall survival was observed. The higher levels of transcription and expression of HSP90AA1 and the activity of AKT1/ERK pathways were confirmed in lung cancer patient tissues. In both human and mouse lung cancer cell lines, knocking down HSP90AA1 promoted cell apoptosis through the inhibition of the pro-survival effect of AKT1 by decreasing the phosphorylation of itself and its downstream factors of mTOR and BAD, as well as downregulating Mcl1, Bcl-xl, and Survivin. The knockdown also suppressed lung cancer cell proliferation by inhibiting ERK activation and downregulating CyclinD1 expression. The treatment of 17-DMAG, an HSP90 inhibitor, recaptured these effects in vitro and inhibited tumor cell growth, and induced apoptosis without obvious side effects in lung tumor xenograft mouse models. This study suggests that targeting HSP90 by 17-DMAG could be a potential therapy for the treatment of lung cancer.

Phase 1 multicenter study of the HSP90 inhibitor SNX-5422 plus carboplatin and paclitaxel in patients with lung cancers

OBJECTIVES

Single-agent heat shock protein 90 (HSP90) inhibition has demonstrated activity in oncogene-driven non-small cell and small cell lung cancers. SNX-5422 is an oral HSP90 inhibitor with increased activity in vitro with the addition of carboplatin and paclitaxel. Therefore, we conducted a phase 1, open-label, multicenter study to evaluate SNX-5422, carboplatin and paclitaxel followed by SNX-5422 maintenance in patients with advanced lung cancers.

MATERIALS AND METHODS

In part 1 (3 + 3 dose escalation), SNX-5422 (50/75/100-mg/m²) was dosed every other day (qod) for 21 days (28-day cycle) for ≤4 cycles; carboplatin (AUC 5)-paclitaxel (175 mg/m²) was administered once every 3 weeks for ≤6 courses. In part 2 (maintenance), subjects who achieved at least stable disease in part 1 received 100 mg/m² SNX-5422 monotherapy qod for 21 days (28-day cycle).

RESULTS

Twenty-three patients with advanced non-small cell lung cancer (NSCLC, n = 20) and small cell lung cancer (SCLC, n = 3) were enrolled. The median age was 60 years and 61% (n = 14/23) had ≥1 prior treatment regimens. The maximum tolerated dose of SNX-5422 was 100 mg/m² qod in combination with carboplatin-paclitaxel. The most common treatment-related grade 3/4 adverse events (part 1/part 2) were diarrhea (26%/15%) and nausea (9%/0%). In response-evaluable patients with NSCLC, 33% (6/18) had a partial response, 56% (10/18) stable disease, and 11% (2/18) progressive disease. Patients who remained on single-agent SNX-5422 maintenance therapy ≥2 months (n = 9) had cancers enriched for oncogenic drivers (n = 3 KRAS mutation, n = 1 EGFR exon 20 mutation, n = 1 HER2 mutation, and n = 1 RET fusion).

CONCLUSIONS

The triplet combination of SNX-5422, carboplatin and paclitaxel followed by maintenance SNX-5422 therapy was well-tolerated and showed anti-tumor activity. Cancers for which disease control on single-agent SNX-5422 maintenance was observed were enriched for oncogene-driven NSCLCs.

Pharmacological Inhibition of HSP90 Radiosensitizes Head and Neck Squamous Cell Carcinoma Xenograft by Inhibition of DNA Damage Repair, Nucleotide Metabolism, and Radiation-Induced Tumor Vasculogenesis

PURPOSE

Recent preclinical studies suggest combining the HSP90 inhibitor AT13387 (Onalespib) with radiation (IR) against colon cancer and head and neck squamous cell carcinoma (HNSCC). These studies emphasized that AT13387 downregulates HSP90 client proteins involved in oncogenic signaling and DNA repair mechanisms as major drivers of enhanced radiosensitivity. Given the large array of client proteins HSP90 directs, we hypothesized that other key proteins or signaling pathways may be inhibited by AT13387 and contribute to enhanced radiosensitivity. Metabolomic analysis of HSP90 inhibition by AT13387 was conducted to identify metabolic biomarkers of radiosensitization and whether modulations of key proteins were involved in IR-induced tumor vasculogenesis, a process involved in tumor recurrence.

METHODS AND MATERIALS

HNSCC and non-small cell lung cancer cell lines were used to evaluate the AT13387 radiosensitization effect in vitro and in vivo. Flow cytometry, immunofluorescence, and immunoblot analysis were used to evaluate cell cycle changes and HSP90 client protein's role in DNA damage repair. Metabolic analysis was performed using liquid chromatography-Mass spectrometry. Immunohistochemical examination of resected tumors post-AT13387 and IR treatment were conducted to identify biomarkers of IR-induced tumor vasculogenesis.

RESULTS

In agreement with recent studies, AT13387 treatment combined with IR resulted in a G2/M cell cycle arrest and inhibited DNA repair. Metabolomic profiling indicated a decrease in key metabolites in glycolysis and tricarboxylic acid cycle by AT13387, a reduction in Adenosine 5'-triphosphate levels, and rate-limiting metabolites in nucleotide metabolism, namely phosphoribosyl diphosphate and aspartate. HNSCC xenografts treated with the combination exhibited increased tumor regrowth delay, decreased tumor infiltration of CD45 and CD11b+ bone marrow-derived cells, and inhibition of HIF-1 and SDF-1 expression, thereby inhibiting IR-induced vasculogenesis.

CONCLUSIONS

AT13387 treatment resulted in pharmacologic inhibition of cancer cell metabolism that was linked to DNA damage repair. AT13387 combined with IR inhibited IR-induced vasculogenesis, a process involved in tumor recurrence postradiotherapy. Combining AT13387 with IR warrants consideration of clinical trial assessment.

Longitudinal Analysis of Gene Expression Changes During Cervical Carcinogenesis Reveals Potential Therapeutic Targets

Despite advances in the treatment of cervical cancer (CC), the prognosis of patients with CC remains to be improved. This study aimed to explore candidate gene targets for CC. CC datasets were downloaded from the Gene Expression Omnibus database. Genes with similar expression trends in varying steps of CC development were clustered using Short Time-series Expression Miner (STEM) software. Gene functions were then analyzed using the Gene Ontology (GO) database and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis. Protein interactions among genes of interest were predicted, followed by drug-target genes and prognosis-associated genes. The expressions of the predicted genes were determined using real-time quantitative polymerase chain reaction (RT-qPCR) and Western blotting. Red and green profiles with upward and downward gene expressions, respectively, were screened using STEM software. Genes with increased expression were significantly enriched in DNA replication, cell-cycle-related biological processes, and the p53 signaling pathway. Based on the predicted results of the Drug-Gene Interaction database, 17 drug-gene interaction pairs, including 3 red profile genes (TOP2A, RRM2, and POLA1) and 16 drugs, were obtained. The Cancer Genome Atlas data analysis showed that high POLA1 expression was significantly correlated with prolonged survival, indicating that POLA1 is protective against CC. RT-qPCR and Western blotting showed that the expressions of TOP2A, RRM2, and POLA1 gradually increased in the multistep process of CC. TOP2A, RRM2, and POLA1 may be targets for the treatment of CC. However, many studies are needed to validate our findings.

Chaperoning STAT3/5 by Heat Shock Proteins: Interest of Their Targeting in Cancer Therapy

While cells from multicellular organisms are dependent upon exogenous signals for their survival, growth, and proliferation, commitment to a specific cell fate requires the correct folding and maturation of proteins, as well as the degradation of misfolded or aggregated proteins within the cell. This general control of protein quality involves the expression and the activity of molecular chaperones such as heat shock proteins (HSPs). HSPs, through their interaction with the STAT3/STAT5 transcription factor pathway, can be crucial both for the tumorigenic properties of cancer cells (cell proliferation, survival) and for the microenvironmental immune cell compartment (differentiation, activation, cytokine secretion) that contributes to immunosuppression, which, in turn, potentially promotes tumor progression. Understanding the contribution of chaperones such as HSP27, HSP70, HSP90, and HSP110 to the STAT3/5 signaling pathway has raised the possibility of targeting such HSPs to specifically restrain STAT3/5 oncogenic functions. In this review, we present how HSPs control STAT3 and STAT5 activation, and vice versa, how the STAT signaling pathways modulate HSP expression. We also discuss whether targeting HSPs is a valid therapeutic option and which HSP would be the best candidate for such a strategy.

Cytotoxic activity of IMMUNEPOTENT CRP against non-small cell lung cancer cell lines

BACKGROUND

IMMUNEPOTENT-CRP® (I-CRP) is a bovine dialyzable leukocyte extract containing transfer factor. It is a cost-effective, unspecific active immunotherapy that has been used in patients with non-small cell lung cancer (NSCLC) as an adjuvant to reduce the side-effects of chemotherapy and radiotherapy, and has shown cytotoxic activity in vitro on different cancer cell lines. However, its mechanism of action against lung cancer cells has not been assessed. Therefore, the objective of this work was to assess the cytotoxic mechanism of I-CRP on lung cancer cell lines.

METHODS

We assessed cell viability through MTT assay on the NSCLC cell lines A549, A427, Calu-1, and INER-51 after treatment with I-CRP. To further understand the mechanisms of cell viability diminution we used fluorescence-activated cell sorting to evaluate cell death (annexin-V and propidium iodide [PI] staining), cell cycle and DNA degradation (PI staining), mitochondrial alterations (TMRE staining), and reactive oxygen species (ROS) production (DCFDA staining). Additionally, we evaluated caspase and ROS dependence of cell death by pretreating the cells with the pan-caspase inhibitor Q-VD-OPH and the antioxidant N-acetylcysteine (NAC), respectively.

RESULTS

Our data shows that I-CRP is cytotoxic to NSCLC cell lines in a dose and time dependent manner, without substantial differences between the four cell lines tested (A549, A427, Calu-1, and INER-51). Cytotoxicity is induced through regulated cell death and cell cycle arrest induction. I-CRP-induced cell death in NSCLC cell lines is characterized by DNA degradation, mitochondrial damage, and ROS production. Moreover, cell death is independent of caspases but relies on ROS production, as it is abrogated with NAC.

CONCLUSION

Altogether, these results improve the knowledge about the cytotoxic activity of I-CRP on NSCLC cells, indicating that cell death, cell cycle arrest, DNA degradation and mitochondrial damage are important features, while ROS play the main role for I-CRP mediated cytotoxicity in lung cancer cells.

Unfolded Protein Response (UPR) in Survival, Dormancy, Immunosuppression, Metastasis, and Treatments of Cancer Cells

The endoplasmic reticulum (ER) has diverse functions, and especially misfolded protein modification is in the focus of this review paper. With a highly regulatory mechanism, called unfolded protein response (UPR), it protects cells from the accumulation of misfolded proteins. Nevertheless, not only does UPR modify improper proteins, but it also degrades proteins that are unable to recover. Three pathways of UPR, namely PERK, IRE-1, and ATF6, have a significant role in regulating stress-induced physiological responses in cells. The dysregulated UPR may be involved in diseases, such as atherosclerosis, heart diseases, amyotrophic lateral sclerosis (ALS), and cancer. Here, we discuss the relation between UPR and cancer, considering several aspects including survival, dormancy, immunosuppression, angiogenesis, and metastasis of cancer cells. Although several moderate adversities can subject cancer cells to a hostile environment, UPR can ensure their survival. Excessive unfavorable conditions, such as overloading with misfolded proteins and nutrient deprivation, tend to trigger cancer cell death signaling. Regarding dormancy and immunosuppression, cancer cells can survive chemotherapies and acquire drug resistance through dormancy and immunosuppression. Cancer cells can also regulate the downstream of UPR to modulate angiogenesis and promote metastasis. In the end, regulating UPR through different molecular mechanisms may provide promising anticancer treatment options by suppressing cancer proliferation and progression.

Hsp90 Inhibitor SNX-2112 Enhances TRAIL-Induced Apoptosis of Human Cervical Cancer Cells via the ROS-Mediated JNK-p53-Autophagy-DR5 Pathway

Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) is a potent cancer cell apoptosis-inducing factor that can induce apoptosis in a variety of cancer cells. However, resistance to TRAIL in cancer cells is a huge obstacle in creating effective TRAIL-targeted clinical therapies. Thus, agents that can either enhance the effect of TRAIL or overcome its resistance are needed. In this study, we combined TRAIL with SNX-2112, an Hsp90 inhibitor we previously developed, to explore the effect and mechanism that SNX-2112 enhanced TRAIL-induced apoptosis in cervical cancer cells. Our results showed that SNX-2112 markedly enhanced TRAIL-induced cytotoxicity in HeLa cells, and this combination was found to be synergistic. Additionally, we found that SNX-2112 sensitized TRAIL-mediated apoptosis caspase-dependently in TRAIL-resistant HeLa cells. Mechanismly, SNX-2112 downregulated antiapoptosis proteins, including Bcl-2, Bcl-XL, and FLIP, promoted the accumulation of reactive oxygen species (ROS), and increased the expression levels of p-JNK and p53. ROS scavenger NAC rescued SNX-2112/TRAIL-induced apoptosis and suppressed SNX-2112-induced p-JNK and p53. Moreover, SNX-2112 induced the upregulation of death-receptor DR5 in HeLa cells. The silencing of DR5 by siRNA significantly decreased cell apoptosis by the combined effect of SNX-2112 and TRAIL. In addition, SNX-2112 inhibited the Akt/mTOR signaling pathway and induced autophagy in HeLa cells. The blockage of autophagy by bafilomycin A1 or Atg7 siRNA abolished SNX-2112-induced upregulation of DR5. Meanwhile, ROS scavenger NAC, JNK inhibitor SP600125, and p53 inhibitor PFTα were used to verify that autophagy-mediated upregulation of DR5 was regulated by the SNX-2112-stimulated activation of the ROS-JNK-p53 signaling pathway. Thus, the combination of SNX-2112 and TRAIL may provide a novel strategy for the treatment of human cervical cancer by overcoming cellular mechanisms of apoptosis resistance.

Genomic, Pathway Network, and Immunologic Features Distinguishing Squamous Carcinomas

This integrated, multiplatform PanCancer Atlas study co-mapped and identified distinguishing molecular features of squamous cell carcinomas (SCCs) from five sites associated with smoking and/or human papillomavirus (HPV). SCCs harbor 3q, 5p, and other recurrent chromosomal copy-number alterations (CNAs), DNA mutations, and/or aberrant methylation of genes and microRNAs, which are correlated with the expression of multi-gene programs linked to squamous cell stemness, epithelial-to-mesenchymal differentiation, growth, genomic integrity, oxidative damage, death, and inflammation. Low-CNA SCCs tended to be HPV(+) and display hypermethylation with repression of TET1 demethylase and FANCF, previously linked to predisposition to SCC, or harbor mutations affecting CASP8, RAS-MAPK pathways, chromatin modifiers, and immunoregulatory molecules. We uncovered hypomethylation of the alternative promoter that drives expression of the ΔNp63 oncogene and embedded miR944. Co-expression of immune checkpoint, T-regulatory, and Myeloid suppressor cells signatures may explain reduced efficacy of immune therapy. These findings support possibilities for molecular classification and therapeutic approaches.

HSP90 inhibition sensitizes head and neck cancer to platin-based chemoradiotherapy by modulation of the DNA damage response resulting in chromosomal fragmentation

BACKGROUND

Concurrent cisplatin radiotherapy (CCRT) is a current standard-of-care for locally advanced head and neck squamous cell carcinoma (HNSCC). However, CCRT is frequently ineffective in patients with advanced disease. It has previously been shown that HSP90 inhibitors act as radiosensitizers, but these studies have not focused on CCRT in HNSCC. Here, we evaluated the HSP90 inhibitor, AUY922, combined with CCRT.

METHODS

The ability of AUY922 to sensitize to CCRT was assessed in p53 mutant head and neck cell lines by clonogenic assay. Modulation of the CCRT induced DNA damage response (DDR) by AUY922 was characterized by confocal image analysis of RAD51, BRCA1, 53BP1, ATM and mutant p53 signaling. The role of FANCA depletion by AUY922 was examined using shRNA. Cell cycle checkpoint abrogation and chromosomal fragmentation was assessed by western blot, FACS and confocal. The role of ATM was also assessed by shRNA. AUY922 in combination with CCRT was assessed in vivo.

RESULTS

The combination of AUY922 with cisplatin, radiation and CCRT was found to be synergistic in p53 mutant HNSCC. AUY922 leads to significant alterations to the DDR induced by CCRT. This comprises inhibition of homologous recombination through decreased RAD51 and pS1524 BRCA1 with a corresponding increase in 53BP1 foci, activation of ATM and signaling into mutant p53. A shift to more error prone repair combined with a loss of checkpoint function leads to fragmentation of chromosomal material. The degree of disruption to DDR signalling correlated to chromosomal fragmentation and loss of clonogenicity. ATM shRNA indicated a possible rationale for the combination of AUY922 and CCRT in cells lacking ATM function.

CONCLUSIONS

This study supports future clinical studies combining AUY922 and CCRT in p53 mutant HNSCC. Modulation of the DDR and chromosomal fragmentation are likely to be analytical points of interest in such trials.

Analysis of HSP90 Expression Is Valuable in the Differential Diagnosis of Ocular Surface Squamous Lesions

OBJECTIVES

The aim of this study was to evaluate heat shock protein 90 (HSP90) expression in squamous lesions (SLs) and to assess its diagnostic value for different lesions within the SL spectrum.

METHODS

A total of 70 conjunctival SLs, including 19 papillomas, 22 cases of conjunctival intraepithelial neoplasia (ConINs) I, 11 cases of ConIN II, six cases of ConIN III, and 12 squamous carcinomas (sqCAs), were evaluated using the German immunoreactive score against HSP90.

RESULTS

Cytoplasmic HSP90 expression differed between low- and high-grade lesions (P < .001). Among high-grade lesions, the nuclear HSP90 score was higher in the ConIN III-sqCA group than in the ConIN II group (P = .0162). A percentage of total thickness staining of less than 73% differentiated between ConIN III and sqCA.

CONCLUSIONS

The expression of HSP90 is particularly useful to differentiate low-grade from high-grade lesions of the conjunctiva. HSP90 may play an important role in the malignant transformation of SLs and could be a new target for therapy.

Combination of SNX-2112 with 5-FU exhibits antagonistic effect in esophageal cancer cells

The low efficacy of single-drug chemotherapy forms the basis for combination therapy in esophageal squamous cell carcinoma. SNX-2112, a selective heat shock protein 90 (Hsp90) inhibitor, was recently reported as being effective in combination with cisplatin and paclitaxel. In this study, we investigated the effect of SNX-2112 in combination with 5-fluorouracil (5-FU), another first-line anticancer drug, in esophageal cancer. Unexpectedly, tetrazolium assay revealed that the combination of SNX-2112 with 5-FU exhibited antagonistic effect. Flow cytometry revealed that the SNX-2112 and 5-FU combination greatly decreased the number of G2/M cells compared to SNX-2112-only treatment in Eca‑109 cells. This effect might be related to the altered mRNA level of cyclin-related genes including cyclin D1, Chk2 and Cdk4. Further, 5-FU attenuated SNX-2112-induced apoptosis by decreasing poly(ADP-ribose) polymerase (PARP) cleavage and inactivating caspase-3, -8 and -9. Additionally, 5-FU suppressed the SNX-2112-induced decrease of mitochondrial membrane potential. Moreover, 5-FU partly recovered Hsp90 client proteins, including Akt, p-Akt, inhibitor of κB kinase (IKK)α, extracellular signal-regulated kinase (ERK)1/2, and glycogen synthase kinase (GSK)-3β, which SNX-2112 had downregulated. Taken together, this is the first report that the combination of SNX-2112 with 5-FU exhibited antagonistic effect in esophageal cancer cells by affecting growth inhibition, cell cycle, apoptosis, and Hsp90 client proteins, suggesting that care is required in the clinical application of combined SNX-2112 and 5-FU.

Phase I dose-escalation studies of SNX-5422, an orally bioavailable heat shock protein 90 inhibitor, in patients with refractory solid tumours

BACKGROUND

Orally administered SNX-5422, a novel, selective prodrug of the Heat shock protein 90 (Hsp90) inhibitor SNX-2112, was investigated in two sequential phase I studies to determine the safety, maximum tolerated doses (MTDs) and pharmacokinetic profile of SNX-5422.

METHODS

Using a dose-escalation design, 3-6 adults with advanced solid tumours received SNX-5422 every-other-day (QOD) or once-daily (QD) 3weeks on/1week off or QD continuously, with disease assessments every 8 weeks. Single-dose and steady-state pharmacokinetic parameters of SNX-2112 were determined.

RESULTS

In total, 56 patients were enrolled: QOD 3 weeks on/1 week off, n=36; QD 3weeks on/1 week off, n=17; QD continuous, n=3. Doses ranged from 4 to 133mg/m(2) QOD and 50 to 89 mg/m(2) QD. The MTDs were defined as 100mg/m(2) QOD and 67 mg/m(2) QD, respectively, with diarrhoea being dose-limiting on both 3 weeks on/1 week off schedules. Overall, treatment-related adverse events were mainly low grade, including diarrhoea (64%), nausea (39%), fatigue (28%), and vomiting (28%). Reversible grade 1-3 nyctalopia (night blindness) was reported by four patients (dose: 50-89mg/m(2) QD; 100mg/m(2) QOD). Exposure was generally linear, though greater than dose-proportional. Of 32 evaluable patients on QOD dosing, there was one durable complete response (prostate cancer), one confirmed (HER2+breast cancer) and one unconfirmed partial response (adrenal gland cancer). Three patients (QOD schedule) had stable disease for ⩾ 6 months.

CONCLUSIONS

The dose and schedule recommended for further study with SNX-5422 is 100mg/m(2) QOD 3 weeks on/1 week off based on improved tolerability and preliminary evidence of clinical activity.