A metabolic perspective on nitric oxide function in melanoma.

Nitric oxide (NO) generated from nitric oxide synthase (NOS) exerts a dichotomous effect in melanoma, suppressing or promoting tumor progression. This dichotomy is thought to depend on the intracellular NO concentration and the cell type in which it is generated. Due to its central role in the metabolism of multiple critical constituents involved in signaling and stress, it is crucial to explore NO's contribution to the metabolic dysfunction of melanoma. This review will discuss many known metabolites linked to NO production in melanoma. We discuss the synthesis of these metabolites, their role in biochemical pathways, and how they alter the biological processes observed in the melanoma tumor microenvironment. The metabolic pathways altered by NO and the corresponding metabolites reinforce its dual role in melanoma and support investigating this effect for potential avenues of therapeutic intervention.

The HSP90 inhibitor ganetespib potentiates the antitumor activity of EGFR tyrosine kinase inhibition in mutant and wild-type non-small cell lung cancer.

Small molecule inhibitors of epidermal growth factor receptor (EGFR) tyrosine kinase activity, such as erlotinib and gefitinib, revolutionized therapy for non-small cell lung cancer (NSCLC) patients whose tumors harbor activating EGFR mutations. However, mechanisms to overcome the invariable development of acquired resistance to such agents, as well as realizing their full clinical potential within the context of wild-type EGFR (WT-EGFR) disease, remain to be established. Here, the antitumor efficacy of targeted EGFR tyrosine kinase inhibitors (TKIs) and the HSP90 inhibitor ganetespib, alone and in combination, were evaluated in NSCLC. Ganetespib potentiated the efficacy of erlotinib in TKI-sensitive, mutant EGFR-driven NCI-HCC827 xenograft tumors, with combination treatment causing significant tumor regressions. In erlotinib-resistant NCI-H1975 xenografts, concurrent administration of ganetespib overcame erlotinib resistance to significantly improve tumor growth inhibition. Ganetespib co-treatment also significantly enhanced antitumor responses to afatinib in the same model. In WT-EGFR cell lines, ganetespib potently reduced cell viability. In NCI-H1666 cells, ganetespib-induced loss of client protein expression, perturbation of oncogenic signaling pathways, and induction of apoptosis translated to robust single-agent activity in vivo. Dual ganetespib/erlotinib therapy induced regressions in NCI-H322 xenograft tumors, indicating that the sensitizing properties of ganetespib for erlotinib were conserved within the WT-EGFR setting. Mechanistically, combined ganetespib/erlotinib exposure stabilized EGFR protein levels in an inactive state and completely abrogated extracellular-signal-regulated kinase (ERK) and AKT signaling activity. Thus, selective HSP90 blockade by ganetespib represents a potentially important complementary strategy to targeted TKI inhibition alone for inducing substantial antitumor responses and overcoming resistance, in both the mutant and WT-EGFR settings.

HSP90 Inhibitor-SN-38 Conjugate Strategy for Targeted Delivery of Topoisomerase I Inhibitor to Tumors.

The clinical benefits of chemotherapy are commonly offset by insufficient drug exposures, narrow safety margins, and/or systemic toxicities. Over recent decades, a number of conjugate-based targeting approaches designed to overcome these limitations have been explored. Here, we report on an innovative strategy that utilizes HSP90 inhibitor-drug conjugates (HDC) for directed tumor targeting of chemotherapeutic agents. STA-12-8666 is an HDC that comprises an HSP90 inhibitor fused to SN-38, the active metabolite of irinotecan. Mechanistic analyses in vitro established that high-affinity HSP90 binding conferred by the inhibitor backbone could be exploited for conjugate accumulation within tumor cells. In vivo modeling showed that the HSP90 inhibitor moiety was required for selective retention of STA-12-8666, and this enrichment promoted extended release of active SN-38 within the tumor compartment. Indeed, controlled intratumoral payload release by STA-12-8666 contributed to a broad therapeutic window, sustained biomarker activity, and remarkable degree of efficacy and durability of response in multiple cell line and patient-derived xenograft models. Overall, STA-12-8666 has been developed as a unique HDC agent that employs a distinct mechanism of targeted drug delivery to achieve potent and sustained antitumor effects. These findings identify STA-12-8666 as a promising new candidate for evaluation as novel anticancer therapeutic.

Overcoming acquired BRAF inhibitor resistance in melanoma via targeted inhibition of Hsp90 with ganetespib.

Activating BRAF kinase mutations serve as oncogenic drivers in over half of all melanomas, a feature that has been exploited in the development of new molecularly targeted approaches to treat this disease. Selective BRAF(V600E) inhibitors, such as vemurafenib, typically induce initial, profound tumor regressions within this group of patients; however, durable responses have been hampered by the emergence of drug resistance. Here, we examined the activity of ganetespib, a small-molecule inhibitor of Hsp90, in melanoma lines harboring the BRAF(V600E) mutation. Ganetespib exposure resulted in the loss of mutant BRAF expression and depletion of mitogen-activated protein kinase and AKT signaling, resulting in greater in vitro potency and antitumor efficacy compared with targeted BRAF and MAP-ERK kinase (MEK) inhibitors. Dual targeting of Hsp90 and BRAF(V600E) provided combinatorial benefit in vemurafenib-sensitive melanoma cells in vitro and in vivo. Importantly, ganetespib overcame mechanisms of intrinsic and acquired resistance to vemurafenib, the latter of which was characterized by reactivation of extracellular signal-regulated kinase (ERK) signaling. Continued suppression of BRAF(V600E) by vemurafenib potentiated sensitivity to MEK inhibitors after acquired resistance had been established. Ganetespib treatment reduced, but not abolished, elevations in steady-state ERK activity. Profiling studies revealed that the addition of a MEK inhibitor could completely abrogate ERK reactivation in the resistant phenotype, with ganetespib displaying superior combinatorial activity over vemurafenib. Moreover, ganetespib plus the MEK inhibitor TAK-733 induced tumor regressions in vemurafenib-resistant xenografts. Overall these data highlight the potential of ganetespib as a single-agent or combination treatment in BRAF(V600E)-driven melanoma, particularly as a strategy to overcome acquired resistance to selective BRAF inhibitors.

FGFR3 translocations in bladder cancer: differential sensitivity to HSP90 inhibition based on drug metabolism.

UNLABELLED: Activating mutations and/or overexpression of FGFR3 are common in bladder cancer, making FGFR3 an attractive therapeutic target in this disease. In addition, FGFR3 gene rearrangements have recently been described that define a unique subset of bladder tumors. Here, a selective HSP90 inhibitor, ganetespib, induced loss of FGFR3-TACC3 fusion protein expression and depletion of multiple oncogenic signaling proteins in RT112 bladder cells, resulting in potent cytotoxicity comparable with the pan-FGFR tyrosine kinase inhibitor BGJ398. However, in contrast to BGJ398, ganetespib exerted pleiotropic effects on additional mitogenic and survival pathways and could overcome the FGFR inhibitor-resistant phenotype of FGFR3 mutant-expressing 97-7 and MHG-U3 cells. Combinatorial benefit was observed when ganetespib was used with BGJ398 both in vitro and in vivo. Interestingly, two additional FGFR3 fusion-positive lines (RT4 and SW480) retained sensitivity to HSP90 inhibitor treatment by the ansamycins 17-AAG and 17-DMAG yet displayed intrinsic resistance to ganetespib or AUY922, both second-generation resorcinol-based compounds. Both cell lines, compared with RT112, expressed considerably higher levels of endogenous UGT1A enzyme; this phenotype resulted in a rapid glucuronidation-dependent metabolism and subsequent efflux of ganetespib from SW780 cells, thus providing a mechanism to account for the lack of bioactivity. IMPLICATIONS: Pharmacologic blockade of the molecular chaperone HSP90 represents a promising approach for treating bladder tumors driven by oncogenic gene rearrangements of FGFR3. Furthermore, UDP-glucuronosyltransferase enzyme expression may serve as a predictive factor for clinical response to resorcinol-based HSP90 inhibitors.

Preclinical activity profile and therapeutic efficacy of the HSP90 inhibitor ganetespib in triple-negative breast cancer.

PURPOSE: Treatment options for patients with triple-negative breast cancer (TNBC) are largely limited to systemic chemotherapies, which have shown disappointing efficacy in the metastatic setting. Here, we undertook a comprehensive evaluation of the activity of ganetespib, a potent inhibitor of HSP90, in this malignancy. EXPERIMENTAL DESIGN: The antitumor and antimetastatic activity of ganetespib was investigated using TNBC cell lines and xenograft models. Combinatorial drug analyses were performed with chemotherapeutic agents and concomitant effects on DNA damage and cell-cycle disruption were assessed in vitro; antitumor efficacy was assessed in vivo. Metabolic and objective tumor responses were evaluated in patients with metastatic TNBC undergoing ganetespib treatment. RESULTS: Ganetespib simultaneously deactivated multiple oncogenic pathways to potently reduce cell viability in TNBC cell lines, and suppressed lung metastases in experimental models. Ganetespib potentiated the cytotoxic activity of doxorubicin via enhanced DNA damage and mitotic arrest, conferring superior efficacy to the doxorubicin-cyclophosphamide regimen in TNBC xenografts. Ganetespib also promoted mitotic catastrophe and apoptosis in combination with taxanes in vitro, and these effects translated to significantly improved combinatorial activity in vivo. Marked tumor shrinkage of metastatic lung and lymphatic lesions were seen in patients on ganetespib monotherapy. CONCLUSION: The preclinical activity profile and clinical evidence of tumor regression suggest that ganetespib offers considerable promise as a new therapeutic candidate to target TNBC.

Los Procesos de Comunicación Educativos sobre el Cáncer de Próstata / The Educational Communication Processes on Prostate Cancer

Introducción: El cáncer de próstata es una neoplasia en la cual la comunicación y el conocimiento de la población puede ayudar al diagnóstico temprano y tratamiento temprano. El objetivo de este estudio fue investigar que conocen los pacientes y acompañantes sobre los procesos de comunicación educativa para la salud en cáncer de próstata. Métodos: El presente estudio descriptivo, fue realizado en el Instituto Oncológico Nacional "Dr Juan Tanca Marengo" Solca-Guayaquil. Se utilizó una encuesta de salud sobre el conocimiento de la entidad nosológica, el conocimiento de los métodos diagnósticos y la predisposición a acudir a charlas educativas. La muestra fue calculada en 80 encuestas a familiares, acompañantes y pacientes del Instituto. Resultados: Se registraron 80 encuestas. Sobre el cáncer de próstata el 52.5 % de los encuestados declara no tener conocimiento alguno sobre el mismo, un 31.25 % asegura tener poco conocimiento sobre el cáncer de próstata, y el 16.25 % declara tener un conocimiento apropiado sobre el cáncer de próstata. Sobre el diagnóstico de Cáncer de Próstata el 58.75 % de los encuestados no sabe cómo se diagnostica, un 22.5% % está informado someramente y un 18.75 % tiene conocimiento del diagnóstico. Conclusión: En este reporte se evidencia el desconocimiento sobre cáncer de próstata que tienen los encuestados sobre su concepto y diagnóstico

Introduction: Prostate cancer is a neoplasm in which communication and knowledge of the population can help early diagnosis and early treatment. The objective of this study was to investigate what patients and companions know about the processes of educational communication for health in prostate cancer. Methods: The present descriptive study was carried out in the National Drugs Institute "Dr Juan Tanca Marengo" Solca-Guayaquil. A health survey was used on the knowledge of the nosological entity, the knowledge of the diagnostic methods and the predisposition to attend educational talks. The sample was calculated in 80 surveys to relatives, companions and patients of the Institute. Results: 80 surveys were registered. Regarding prostate cancer, 52.5% of the respondents declare to have no knowledge about it, 31.25% claim to have little knowledge about prostate cancer, and 16.25% declare to have an appropriate knowledge about prostate cancer. About the diagnosis of Prostate Cancer, 58.75% of respondents do not know how it is diagnosed, 22.5%% is briefly informed and 18.75% have knowledge of the diagnosis. Conclusion: This report shows the lack of knowledge about prostate cancer that respondents have about their concept and diagnosis.

Targeted inhibition of the molecular chaperone Hsp90 overcomes ALK inhibitor resistance in non-small cell lung cancer.

UNLABELLED: EML4-ALK gene rearrangements define a unique subset of patients with non-small cell lung carcinoma (NSCLC), and the clinical success of the anaplastic lymphoma kinase (ALK) inhibitor crizotinib in this population has become a paradigm for molecularly targeted therapy. Here, we show that the Hsp90 inhibitor ganetespib induced loss of EML4-ALK expression and depletion of multiple oncogenic signaling proteins in ALK-driven NSCLC cells, leading to greater in vitro potency, superior antitumor efficacy, and prolonged animal survival compared with results obtained with crizotinib. In addition, combinatorial benefit was seen when ganetespib was used with other targeted ALK agents both in vitro and in vivo. Importantly, ganetespib overcame multiple forms of crizotinib resistance, including secondary ALK mutations, consistent with activity seen in a patient with crizotinib-resistant NSCLC. Cancer cells driven by ALK amplification and oncogenic rearrangements of ROS1 and RET kinase genes were also sensitive to ganetespib exposure. Taken together, these results highlight the therapeutic potential of ganetespib for ALK-driven NSCLC. SIGNIFICANCE: In addition to direct kinase inhibition, pharmacologic blockade of the molecular chaperone Hsp90 is emerging as a promising approach for treating tumors driven by oncogenic rearrangements of ALK. The bioactivity profi le of ganetespib presented here underscores a new therapeutic opportunity to target ALK and overcome multiple mechanisms of resistance in patients with ALK-positive NSCLC.

Aislamiento de Pseudomonas aeruginosa en serpientes ecuatorianas y su potencial repercusión en accidentes ofídicos / Isolation of pseudomonas aeruginosa in ecuadorian snakes and their potential impact on snakebite accidents

Debido a la alta incidencia de mordeduras de serpientes, la Organización Mundial de la Salud (OMS) ha catalogado estos accidentes como una de las enfermedades tropicales desatendidas más importantes del planeta. En Ecuador los accidentes ocasionados por mordeduras de serpientes representan un alto riesgo para la vida. Este país registra un promedio de 1.657 casos de mordeduras de serpientes al año (considerando reportes de CIVE MSP desde el 2014 al 2016). Las infecciones secundarias son una de las principales complicaciones en accidentes ofídicos. Pseudomonas aeruginosa es un patógeno oportunista, gramnegativo, cosmopolita y ampliamente vinculado con infecciones graves en pacientes hospitalizados; en este contexto se considera como factor de riesgo la disrupción de la piel causada por mordeduras de serpientes y la afectación del sistema inmunitario a causa del envenenamiento ofídico. El objetivo de la investigación fue determinar la presencia de P. aeruginosa en la cavidad bucal de serpientes ecuatorianas mantenidas en cautiverio con la finalidad de evidenciar un indicador de potenciales infecciones secundarias por estemicroorganismo. El estudio se realizó en 136 serpientes de diferentes géneros y especies, de las cuales el 33,09 % resultó positivo a P. aeruginosa. El muestreo se realizó por hisopado directo, en la parte superior e inferior de la cavidad bucal de las serpientes. Las muestras fueron cultivadas en agar Cetrimide. El estudio se apoyó en las técnicas de tinción de Gram y pruebas bioquímicas confirmatorias. Los estudios de sensibilidad evidenciaron que el antibiótico más activo frente a P. aeruginosa fue el imipenem, demostrando variabilidad en resistencia a los otros antibióticos.

Due to the high incidence of snake bites, WHO has classified these accidents as one of the most important neglected tropical diseases on the planet. In Ecuador, accidents caused by snake bites represent a high risk for life. This country records an average of 1657 cases of snake bites per year (considering reports from CIVE MSP from 2014 to 2016). Secondary infections are one of the major complications in ophidian accidents. Pseudomonas aeruginosa is an opportunistic, gram-negative, cosmopolitan pathogen that is widely associated with severe infections in hospitalized patients; in this context, disruption of the skin caused by snake bites and impingement of the immune system due to poisoning is considered a risk factor. The objective of the investigation was to determine the presence of P. aeruginosa in the oral cavity of Ecuadorian snakes kept in captivity in order to evidence an indicator of potential secondary infections by this microorganism. The study wason 136 snakes of different genera and species, of which 33,09 % were positive for P. aeruginosa. Sampling was performed bydirect swabbing, at the top and bottom of the buccal cavity of the snakes. The samples were cultured on Cetrimide agar. The study was based on Gram staining techniques and confirmatory biochemical tests. Sensitivity studies showed that the most active antibiotic against P. aeruginosa was imipenem, demonstrating variability in resistance to other antibiotics.

Ganetespib (STA-9090), a nongeldanamycin HSP90 inhibitor, has potent antitumor activity in in vitro and in vivo models of non-small cell lung cancer.

PURPOSE: We describe the anticancer activity of ganetespib, a novel non-geldanamycin heat shock protein 90 (HSP90) inhibitor, in non-small cell lung cancer (NSCLC) models. EXPERIMENTAL DESIGN: The activity of ganetespib was compared with that of the geldanamycin 17-AAG in biochemical assays, cell lines, and xenografts, and evaluated in an ERBB2 YVMA-driven mouse lung adenocarcinoma model. RESULTS: Ganetespib blocked the ability of HSP90 to bind to biotinylated geldanamycin and disrupted the association of HSP90 with its cochaperone, p23, more potently than 17-AAG. In genomically defined NSCLC cell lines, ganetespib caused depletion of receptor tyrosine kinases, extinguishing of downstream signaling, inhibition of proliferation and induction of apoptosis with IC(50) values ranging 2 to 30 nmol/L, substantially lower than those required for 17-AAG (20-3,500 nmol/L). Ganetespib was also approximately 20-fold more potent in isogenic Ba/F3 pro-B cells rendered IL-3 independent by expression of EGFR and ERBB2 mutants. In mice bearing NCI-H1975 (EGFR L858R/T790M) xenografts, ganetespib was rapidly eliminated from plasma and normal tissues but was maintained in tumor with t(1/2) 58.3 hours, supporting once-weekly dosing experiments, in which ganetespib produced greater tumor growth inhibition than 17-AAG. However, after a single dose, reexpression of mutant EGFR occurred by 72 hours, correlating with reversal of antiproliferative and proapoptotic effects. Consecutive day dosing resulted in xenograft regressions, accompanied by more sustained pharmacodynamic effects. Ganetespib also showed activity against mouse lung adenocarcinomas driven by oncogenic ERBB2 YVMA. CONCLUSIONS: Ganetespib has greater potency than 17-AAG and potential efficacy against several NSCLC subsets, including those harboring EGFR or ERBB2 mutation.