Balancing Affinity, Selectivity, and Cytotoxicity of Hydrazone-Based G-Quadruplex Ligands for Activation of Interferon ß Genes in Cancer Cells.

G-quadruplex (G4) ligands are investigated to discover new anticancer drugs with increased cell-killing potency. These ligands can induce genome instability and activate innate immune genes at non-cytotoxic doses, opening the discovery of cytostatic immune-stimulating ligands. However, the interplay of G4 affinity/selectivity with cytotoxicity and immune gene activation is not well-understood. We investigated a series of closely related hydrazone derivatives to define the molecular bases of immune-stimulation activity. Although they are closely related to each other, such derivatives differ in G4 affinity, cytotoxicity, genome instability, and immune gene activation. Our findings show that G4 affinity of ligands is a critical feature for immune gene activation, whereas a high cytotoxic potency interferes with it. The balance of G4 stabilization versus cytotoxicity can determine the level of immune gene activation in cancer cells. Thus, we propose a new rationale based on low cell-killing potency and high immune stimulation to discover effective anticancer G4 ligands.

Topoisomerase I poison-triggered immune gene activation is markedly reduced in human small-cell lung cancers by impairment of the cGAS/STING pathway.

BACKGROUND: Current immunotherapy strategies have contrasting clinical results in human lung cancer patients as small-cell lung cancers (SCLC) often show features of immunological cold tumours. Topoisomerase 1 (TOP1) poisons are effective antitumor drugs with good efficacy against lung cancers. METHODS: We used molecular, genetic and bioinformatic approaches to determine the mechanism of micronuclei formation induced by two TOP1 poisons in different human cancer cells, including SCLC cell lines. RESULTS: TOP1 poisons stimulate similar levels of micronuclei in all tested cell lines but downstream effects can vary markedly. TOP1 poisons increase micronuclei levels with a mechanism involving R-loops as overexpression of RNaseH1 markedly reduces or abolishes both H2AX phosphorylation and micronuclei formation. TOP1 poison-induced micronuclei activate the cGAS/STING pathway leading to increased expression of immune genes in HeLa cells, but not in human SCLC cell lines, mainly due to lack of STING and/or cGAS expression. Moreover, the expression of STING and antigen-presenting machinery genes is generally downregulated in patient tumours of human lung cancer datasets. CONCLUSIONS: Altogether, our data reveal an immune signalling mechanism activated by TOP1 poisons, which is often impaired in human SCLC tumours.

Stemness underpinning all steps of human colorectal cancer defines the core of effective therapeutic strategies.

BACKGROUND: Despite their lethality and ensuing clinical and therapeutic relevance, circulating tumor cells (CTCs) from colorectal carcinoma (CRC) remain elusive, poorly characterized biological entities. METHODS AND FINDINGS: We perfected a cell system of stable, primary lines from human CRC showing that they possess the full complement of ex- and in-vivo, in xenogeneic models, characteristics of CRC stem cells (CCSCs). Here we show how tumor-initiating, CCSCs cells can establish faithful orthotopic phenocopies of the original disease, which contain cells that spread into the circulatory system. While in the vascular bed, these cells retain stemness, thus qualifying as circulating CCSCs (cCCSCs). This is followed by the establishment of lesions in distant organs, which also contain resident metastatic CCSCs (mCCSCs). INTERPRETATION: Our results support the concept that throughout all the stages of CRC, stemness is retained as a continuous property by some of their tumor cells. Importantly, we describe a useful standardized model that can enable isolation and stable perpetuation of human CRC's CCSCs, cCCSCs and mCCSCs, providing a useful platform for studies of CRC initiation and progression that is suitable for the discovery of reliable stage-specific biomarkers and the refinement of new patient-tailored therapies. FUND: This work was financially supported by grants from "Ministero della Salute Italiano"(GR-2011-02351534, RC1703IC36 and RC1803IC35) to Elena Binda and from "Associazione Italiana Cancro" (IG-14368) Angelo L. Vescovi. None of the above funders have any role in study design, data collection, data analysis, interpretation, writing the project.

Sofosbuvir and ribavirin for genotype 2 HCV infected patients with cirrhosis: A real life experience.

BACKGROUND & AIMS: Sofosbuvir (SOF) and weight-based ribarivin (RBV) represented until recently the standard of care in hepatitis C virus (HCV) genotype (GT)2 patients. In registration studies 12-16weeks duration were associated with a 90% sustained virological response at 12weeks (SVR12). Real life cohorts showed lower SVR12 rates. METHODS: SVR12 rates attained in an Italian real life cohort and possible benefits of a duration extended up to 20weeks was investigated in HCV GT2 patients with cirrhosis. The role of 2k/1b chimeras as potential predictor of treatment failure was also analysed. RESULTS: Overall, 291 HCV GT2 infected patients with bridging fibrosis or cirrhosis were evaluated. Median age was 68years (18-87); 163 were treatment naïve. Of 168 cirrhotic patients, 149 had Child-Pugh score A and 19 B, 50 platelets count <100,000/mm3 and 62 albumin <3.5g/dl. SVR12 were 95.53% overall, with 99.15% in non-cirrhotic patients and 93.06% in cirrhotic patients. In patients who completed treatment, SVR rates for cirrhotic patients resulted in 94.51%, and 94.94% after 16 or 20weeks respectively. Predictors of SVR were low platelet count and esophageal varices (OR 7.2; 95% CI 1.67-31.25; p=0.0022 and OR 0.1; 95% CI 0.01-0.72; p=0.0079, respectively). Anemia was mild in 12.4%, moderate in 3.4%, and severe in 2.4% of cases. Anemia was slightly more frequent among longer duration but not associated with treatment discontinuations. No 2k/1b strains or genotypes different from those at baseline were identified at relapse. CONCLUSIONS: In GT2 cirrhotic patients, SOF/RBV for 16 or 20weeks is associated with real life SVR12 rates of 95%. LAY SUMMARY: A duration of treatment of 16-20weeks was recommended for treatment of HCV GT2 patients using the combination of sofosbuvir and ribavirin. Real life experiences, where patients received 12weeks of treatment regardless of the severity of liver disease, suggested that response rates are lower than expected, in particular in patients with liver cirrhosis. A misleading genotyping of a 2k/1b strain as GT2 was also hypothesized as a further explanation for less effectiveness. We demonstrated that using the recommended extended duration in patients with more severe disease 95% of patients with severe liver disease including cirrhosis can be cured and that 2k/1b strain plays only a secondary role in specific countries like Germany. Although this combination has been recently replaced by sofosbuvir and velpatasvir fixed dose combination as the standard of care for treating HCV GT2 patients, our findings may inform physicians from countries where the new regimen is not yet available.

The combination of daclatasvir and sofosbuvir for curing genotype 2 patients who cannot tolerate ribavirin.

BACKGROUND: The current standard-of-care for treatment of HCV genotype 2 (GT-2) patients is the combination of sofosbuvir (SOF) with weight-based ribavirin (RBV). Patients with HCV GT-2 infection and ribavirin contraindications require the use of SOF plus NS5A inhibitor daclatasvir (DCV) which is not reimbursed everywhere. METHODS: We conducted an open-label observational, prospective study on a subgroup of GT-2 patients either naïve or treatment experienced (TE) with contraindications to the use of RBV. Patients with cirrhosis of Child-Pugh-Turcotte (CPT) class A and B or advanced fibrosis with comorbidities were included. They were assigned to receive 12 or 24 weeks of SOF/DCV. The primary end point of the study was sustained virological response (SVR) defined as HCV RNA levels <12 IU/ml, 12 weeks post treatment. RESULTS: Out of 106 patients with GT-2 who received treatment at our unit from July 2014 to June 2015, 20 (18.8%) patients, whose treatment could not be deferred, were ribavirin intolerant; 19 received SOF/DCV combination for 12 or 24 weeks. The majority of the patients was men, 58% had cirrhosis, and 58% were TE. All treated patients achieved SVR regardless of treatment duration. The most common adverse events (AEs) were fatigue, headache and nausea. No discontinuations due to AEs were observed. Two patients had oesophageal bleeding but continued treatment and achieved SVR; one patient developed HCC 12 weeks post treatment, but remained HCV RNA undetectable. CONCLUSIONS: This study supports the use of SOF/DCV for 12 weeks in non-cirrhotics or 24 weeks in cirrhotic GT-2 patients who cannot tolerate RBV, including those with decompensated disease.

The current treatment of Hepatitis C.

The development of potent antivirals able to directly block multiple step of viral lifecycle (DAAs) led to a revolution in HCV treatment. These compounds are associated with unprecedent high rates of SVR and can be administered orally, regardless of the severity of the associated liver disease, allowing treatment of large number of HCV infected patients. Three main classes of DAAs are currently available, NS3/4 inhibitors, NS5A inhibitors and NS5B inhibitors. They can be combined according to 2 different strategies, the use of a backbone drug with high barrier of resistance as the NS5B inhibitor sofosbuvir, with the addition of a second drug either NS3/4 or NS5A, or the use of more than 1 drug from different classes to simultaneously attack the virus at different sequence sites. DAAs can be administered for 12 or 24 weeks in the majority of patients, although attempts to reduce to 6-8 weeks the treatment duration in patients with baseline favorable characteristics are ongoing. Overall, SVR rates ensured by the currently approved combinations, are 90% or higher. Although cirrhotic patients and in particular patients with decompensated disease may represent a difficult to cure group, data from real life confirm evidence derived from phase III studies, showing improvement in biochemical parameters, even in such a special populations. We can expect, the number of patients with unmet medical needs will decline over time in the next 4 years. This review aims to discuss updated regimens by HCV genotype and to provide a brief summary of the coming strategies.