Splicing modulation as novel therapeutic strategy against diffuse malignant peritoneal mesothelioma

Introduction: Therapeutic options for diffuse malignant peritoneal mesothelioma (DMPM) are limited to surgery and locoregional chemotherapy. Despite improvements in survival rates, patients eventually succumb to disease progression. We investigated splicing deregulation both as molecular prognostic factor and potential novel target in DMPM, while we tested modulators of SF3b complex for antitumor activity. Methods: Tissue-microarrays of 64 DMPM specimens were subjected to immunohistochemical assessment of SF3B1 expression and correlation to clinical outcome. Two primary cell cultures were used for gene expression profiling and in vitro screening of SF3b modulators. Drug-induced splicing alterations affecting downstream cellular pathways were detected through RNA sequencing. Ultimately, we established bioluminescent orthotopic mouse models to test the efficacy of splicing modulation in vivo. Results: Spliceosomal genes are differentially upregulated in DMPM cells compared to normal tissues and high expression of SF3B1 correlated with poor clinical outcome in univariate and multivariate analysis. SF3b modulators (Pladienolide-B, E7107, Meayamycin-B) showed potent cytotoxic activity in vitro with IC50 values in the low nanomolar range. Differential splicing analysis of Pladienolide-B-treated cells revealed abundant alterations of transcripts involved in cell cycle, apoptosis and other oncogenic pathways. This was validated by RT-PCR and functional assays. E7107 demonstrated remarkable in vivo antitumor efficacy, with significant improvement of survival rates compared to vehicle-treated controls. Conclusions: SF3B1 emerged as a novel potential prognostic factor in DMPM. Splicing modulators markedly impair cancer cell viability, resulting also in potent antitumor activity in vivo. Our data designate splicing as a promising therapeutic target in DMPM

Mutant KRAS-driven cancers depend on PTPN11/SHP2 phosphatase

The ubiquitously expressed non-receptor protein tyrosine phosphatase SHP2, encoded by PTPN11, is involved in signal transduction downstream of multiple growth factor, cytokine and integrin receptors. Its requirement for complete RAS-MAPK activation and its role as a negative regulator of JAK-STAT signaling have established SHP2 as an essential player in oncogenic signaling pathways. Recently, a novel potent allosteric SHP2 inhibitor was presented as a viable therapeutic option for receptor tyrosine kinase-driven cancers, but was shown to be ineffective in KRAS-mutant tumor cell lines in vitro. Here, we report a central and indispensable role for SHP2 in oncogenic KRAS-driven tumors. Genetic deletion of Ptpn11 profoundly inhibited tumor development in mutant KRAS-driven murine models of pancreatic ductal adenocarcinoma and non-small-cell lung cancer. We provide evidence for a critical dependence of mutant KRAS on SHP2 during carcinogenesis. Deletion or inhibition of SHP2 in established tumors delayed tumor progression but was not sufficient to achieve tumor regression. However, SHP2 was necessary for resistance mechanisms upon blockade of MEK. Synergy was observed when both SHP2 and MEK were targeted, resulting in sustained tumor growth control in murine and human patient-derived organoids and xenograft models of pancreatic ductal adenocarcinoma and non-small-cell lung cancer. Our data indicate the clinical utility of dual SHP2/MEK inhibition as a targeted therapy approach for KRAS-mutant cancers

Mutant KRAS-driven cancers depend on PTPN11/SHP2 phosphatase

The ubiquitously expressed non-receptor protein tyrosine phosphatase SHP2, encoded by PTPN11, is involved in signal transduction downstream of multiple growth factor, cytokine and integrin receptors1. Its requirement for complete RAS-MAPK activation and its role as a negative regulator of JAK-STAT signaling have established SHP2 as an essential player in oncogenic signaling pathways1-7. Recently, a novel potent allosteric SHP2 inhibitor was presented as a viable therapeutic option for receptor tyrosine kinase-driven cancers, but was shown to be ineffective in KRAS-mutant tumor cell lines in vitro8. Here, we report a central and indispensable role for SHP2 in oncogenic KRAS-driven tumors. Genetic deletion of Ptpn11 profoundly inhibited tumor development in mutant KRAS-driven murine models of pancreatic ductal adenocarcinoma and non-small-cell lung cancer. We provide evidence for a critical dependence of mutant KRAS on SHP2 during carcinogenesis. Deletion or inhibition of SHP2 in established tumors delayed tumor progression but was not sufficient to achieve tumor regression. However, SHP2 was necessary for resistance mechanisms upon blockade of MEK. Synergy was observed when both SHP2 and MEK were targeted, resulting in sustained tumor growth control in murine and human patient-derived organoids and xenograft models of pancreatic ductal adenocarcinoma and non-small-cell lung cancer. Our data indicate the clinical utility of dual SHP2/MEK inhibition as a targeted therapy approach for KRAS-mutant cancers.This work was supported by grants from Deutsche Forschungsgemeinschaft (DFG AL1174/5-1 to H.A. and LE3222/1-1 to M.L.), Deutsche Krebshilfe (no. 111646 and no. 111464 to H.A.; Max Eder Program no. 111273 to M.R.), the Wilhelm Sander Stiftung (2014.052.1 to H.A.) and the Fundación Asociación Española Contra el Cáncer (to B.S.).Peer reviewe

Factors associated with presenting late or with advanced HIV disease in the Netherlands, 1996 2014: Results from a national observational cohort

Objectives: Early testing for HIV and entry into care are crucial to optimise treatment outcomes of HIV-infected patients and to prevent spread of HIV. We examined risk factors for presentation with late or advanced disease in HIV-infected patients in the Netherlands. Methods: HIV-infected patients registered in care between January 1996 and June 2014 were selected from the ATHENA national observational HIV cohort. Risk factors for late presentation and advanced disease were analysed by multivariable logistic regression. Furthermore, geographical differences and time trends were examined. Results: Of 20 965 patients, 53% presented with latestage HIV infection, and 35% had advanced disease. Late presentation decreased from 62% (1996) to 42% (2013), while advanced disease decreased from 46% to 26%. Late presentation only declined significantly among men having sex with men (MSM; p <0.001), but not among heterosexual males (p=0.08) and females (p=0.73). Factors associated with late presentation were: heterosexual male (adjusted OR (aOR), 1.59; 95% CI 1.44 to 1.75 vs MSM), injecting drug use (2.00; CI 1.69 to 2.38), age .50 years (1.46; CI 1.33 to 1.60 vs 30.49 years), region of origin (South-East Asia 2.14; 1.80 to 2.54, sub-Saharan Africa 2.11; 1.88 to 2.36, Surinam 1.59; 1.37 to 1.84, Caribbean 1.31; 1.13 to 1.53, Latin America 1.23; 1.04 to 1.46 vs the Netherlands), and location of HIV diagnosis (hospital 3.27; 2.94 to 3.63, general practitioner 1.66; 1.50 to 1.83, antenatal screening 1.76; 1.38 to 2.34 vs sexually transmitted infection clinic). No association was found for socioeconomic status or level of urbanisation. Compared with Amsterdam, 2 regions had higher adjusted odds and 2 regions had lower odds of late presentation. Results were highly similar for advanced disease. Conclusions: Although the overall rate of late presentation is declining in the Netherlands, targeted programmes to reduce late HIV diagnoses remain needed for all risk groups, but should be prioritised for heterosexual males, migrant populations, people aged ≥50 years and certain regions in the Netherlands