Exploring the molecular landscape of cancer of unknown primary: A comparative analysis with other metastatic cancers.

Cancer of unknown primary (CUP) tumors are biologically very heterogeneous, which complicates stratification of patients for treatment. Consequently, these patients face limited treatment options and a poor prognosis. With this study, we aim to expand on the current knowledge of CUP biology by analyzing two cohorts: a well-characterized cohort of 44 CUP patients, and 213 metastatic patients with known primary. These cohorts were treated at the same institution and characterized by identical molecular assessments. Through comparative analysis of genomic and transcriptomic data, we found that CUP tumors were characterized by high expression of immune-related genes and pathways compared to other metastatic tumors. Moreover, CUP tumors uniformly demonstrated high levels of tumor-infiltrating leukocytes and circulating T cells, indicating a strong immune response. Finally, the genetic landscape of CUP tumors resembled that of other metastatic cancers and demonstrated mutations in established cancer genes. In conclusion, CUP tumors possess a distinct immunophenotype that distinguishes them from other metastatic cancers. These results may suggest an immune response in CUP that facilitates metastatic tumor growth while limiting growth of the primary tumor.

A large-scale chemical modification screen identifies design rules to generate siRNAs with high activity, high stability and low toxicity.

The use of chemically synthesized short interfering RNAs (siRNAs) is currently the method of choice to manipulate gene expression in mammalian cell culture, yet improvements of siRNA design is expectably required for successful application in vivo. Several studies have aimed at improving siRNA performance through the introduction of chemical modifications but a direct comparison of these results is difficult. We have directly compared the effect of 21 types of chemical modifications on siRNA activity and toxicity in a total of 2160 siRNA duplexes. We demonstrate that siRNA activity is primarily enhanced by favouring the incorporation of the intended antisense strand during RNA-induced silencing complex (RISC) loading by modulation of siRNA thermodynamic asymmetry and engineering of siRNA 3'-overhangs. Collectively, our results provide unique insights into the tolerance for chemical modifications and provide a simple guide to successful chemical modification of siRNAs with improved activity, stability and low toxicity.

Improved silencing properties using small internally segmented interfering RNAs.

RNA interference is mediated by small interfering RNAs (siRNAs) that upon incorporation into the RNA-induced silencing complex (RISC) can target complementary mRNA for degradation. Standard siRNA design usually feature a 19-27 base pair contiguous double-stranded region that is believed to be important for RISC incorporation. Here, we describe a novel siRNA design composed of an intact antisense strand complemented with two shorter 10-12 nt sense strands. This three-stranded construct, termed small internally segmented interfering RNA (sisiRNA), is highly functional demonstrating that an intact sense strand is not a prerequisite for RNA interference. Moreover, when using the sisiRNA design only the antisense strand is functional in activated RISC thereby completely eliminating unintended mRNA targeting by the sense strand. Interestingly, the sisiRNA design supports the function of chemically modified antisense strands, which are non-functional within the context of standard siRNA designs. This suggests that the sisiRNA design has a clear potential of improving the pharmacokinetic properties of siRNA in vivo.

The application of human phase 0 microdosing trials: A systematic review and perspectives.

A decreasing number of new therapeutic drugs reaching the clinic has led to the publication of regulatory guidelines on human microdosing trials by the European Medicines Agency in 2004 and the US Food and Drug Administration in 2006. Microdosing trials are defined by the administration of 1/100th of the therapeutic dose and designed to investigate basic drug properties. This review investigates the current application of phase 0 trials in medical research. Thirty-three studies found in PubMed and EMBASE were systematically reviewed for aim and analytical method. Pharmacokinetic studies have been a major focus of phase 0 trials, but drug distribution, drug-drug interactions, imaging and pharmacogenomics have also been investigated. Common analytical methods were tandem mass liquid chromatography, accelerator mass spectrometry and positron emission tomography. New ongoing trials are investigating the pharmacodynamics and chemoresistance of marketed drugs, suggesting that the application of phase 0 trials is still evolving.

Diffuse large B-cell lymphoma classification system that associates normal B-cell subset phenotypes with prognosis.

PURPOSE: Current diagnostic tests for diffuse large B-cell lymphoma use the updated WHO criteria based on biologic, morphologic, and clinical heterogeneity. We propose a refined classification system based on subset-specific B-cell-associated gene signatures (BAGS) in the normal B-cell hierarchy, hypothesizing that it can provide new biologic insight and diagnostic and prognostic value. PATIENTS AND METHODS: We combined fluorescence-activated cell sorting, gene expression profiling, and statistical modeling to generate BAGS for naive, centrocyte, centroblast, memory, and plasmablast B cells from normal human tonsils. The impact of BAGS-assigned subtyping was analyzed using five clinical cohorts (treated with cyclophosphamide, doxorubicin, vincristine, and prednisone [CHOP], n = 270; treated with rituximab plus CHOP [R-CHOP], n = 869) gathered across geographic regions, time eras, and sampling methods. The analysis estimated subtype frequencies and drug-specific resistance and included a prognostic meta-analysis of patients treated with first-line R-CHOP therapy. RESULTS: Similar BAGS subtype frequencies were assigned across 1,139 samples from five different cohorts. Among R-CHOP-treated patients, BAGS assignment was significantly associated with overall survival and progression-free survival within the germinal center B-cell-like subclass; the centrocyte subtype had a superior prognosis compared with the centroblast subtype. In agreement with the observed therapeutic outcome, centrocyte subtypes were estimated as being less resistant than the centroblast subtype to doxorubicin and vincristine. The centroblast subtype had a complex genotype, whereas the centrocyte subtype had high TP53 mutation and insertion/deletion frequencies and expressed LMO2, CD58, and stromal-1-signature and major histocompatibility complex class II-signature genes, which are known to have a positive impact on prognosis. CONCLUSION: Further development of a diagnostic platform using BAGS-assigned subtypes may allow pathogenetic studies to improve disease management.

Utilization of unlocked nucleic acid (UNA) to enhance siRNA performance in vitro and in vivo.

Small interfering RNAs (siRNAs) are now established as a favourite tool to reduce gene expression by RNA interference (RNAi) in mammalian cell culture. However, limitations in potency, duration, delivery and specificity of the gene knockdown (KD) are still major obstacles that need further addressing. Recent studies have successfully improved siRNA performance by the introduction of several types of chemical modifications. Here we explore the effect of incorporating unlocked nucleic acid (UNA) into siRNA designs. The acyclic UNA monomers lack the C2'-C3'-bond of the RNA ribose ring and additively decrease nucleic acid duplex thermostability. We show that UNA-modifications of siRNAs are compatible with efficient RNAi and can improve siRNA performance both in vitro and in vivo. In particular, we find that the destabilizing properties of UNA are well suited to enhance the potency of siRNAs which are heavily modified by other chemical modifications such as locked nucleic acid (LNA), C4'hydroxymethyl-DNA (HM), 2'-O-methyl-RNA (OMe), DNA and 2'-Flouro-DNA (F). Interestingly, we find that naked, but UNA-modified siRNAs have dramatically increased biostability in mice and can induce potent KD in a xenograft model of human pancreas cancer. Hereby UNA constitutes an important type of chemical modification for future siRNA designs.