Segmented poly(A) tails significantly reduce recombination of plasmid DNA without affecting mRNA translation efficiency or half-life.

Extensive research in the past decade has brought mRNA closer to the clinical realization of its therapeutic potential. One common structural feature for all cellular messenger RNAs is a poly(A) tail, which can either be brought in cotranscriptionally via the DNA template (plasmid- or PCR-based) or added to the mRNA in a post-transcriptional enzymatic process. Plasmids containing poly(A) regions recombine in E. coli, resulting in extensive shortening of the poly(A) tail. Using a segmented poly(A) approach, we could significantly reduce recombination of plasmids in E. coli without any negative effect on mRNA half-life and protein expression. This effect was independent of the coding sequence. A segmented poly(A) tail is characterized in that it consists of at least two A-containing elements, each defined as a nucleotide sequence consisting of 40-60 adenosines, separated by a spacer element of different length. Furthermore, reducing the spacer length between the poly(A) segments resulted in higher translation efficiencies compared to homogeneous poly(A) tail and reduced recombination (depending upon the choice of spacer nucleotide). Our results demonstrate the superior potential of segmented poly(A) tails compared to the conventionally used homogeneous poly(A) tails with respect to recombination of the plasmids and the resulting mRNA performance (half-life and translational efficiency).

Delivery of mRNA Therapeutics for the Treatment of Hepatic Diseases.

Promising improvements in the field of transcript therapeutics have clearly enhanced the potential of mRNA as a new pillar for protein replacement therapies. Synthetic mRNAs are engineered to replace mutated mRNAs and to be immunologically inconspicuous and highly stable while maximizing protein expression. Approaches to deliver mRNA into the cellular cytoplasm safely and efficiently have been further developed so that two mRNA-based approaches replacing vascular endothelial growth factor (VEGF) and cystic fibrosis transmembrane conductance regulator (CFTR) have now made it into clinical trials. These studies bring mRNA therapeutics for protein replacement therapy closer to clinical realization. Herein, we provide an overview of preclinical and clinical developments of mRNA therapeutics for liver diseases.

Rare SARS-CoV-2 antibody development in cancer patients.

SARS-CoV-2 antibody development and immunity will be crucial for the further course of the pandemic. Until now, it has been assumed that patients who are infected with SARS-CoV-2 will develop antibodies as has been the case with other coronaviruses, like MERS-CoV and SARS-CoV. In the present study, we analyzed the development of antibodies in 77 patients with an oncologic diagnosis 26 days after positive RT-qPCR testing for SARS-CoV2. RT-qPCR and anti-SARS-CoV2-antibody methods from BGI (MGIEasy Magnetic Beads Virus DNA/RNA Extraction Kit) and Roche (Elecsys Anti-SARS-CoV-2 immunoassay) were used, respectively, according to the manufacturers' specifications. Surprisingly, antibody development was detected in only 6 of 77 individuals with a confirmed history of COVID-19. Despite multiple testing, the remaining patients did not show measurable antibody concentrations in subsequent tests. These results undermine the previous hypothesis that SARS-CoV2 infections are regularly associated with antibody development and cast doubt on the provided immunity to COVID-19. Understanding the adaptive and humoral response to SARS-CoV2 will play a key role in vaccine development and gaining further knowledge on the pathogenesis.

Real world data analysis of next generation sequencing and protein expression in metastatic breast cancer patients.

Next generation sequencing (NGS) together with protein expression analysis is back bone of molecularly targeted therapy in precision medicine. Our retrospective study shows our experience with NGS of 324 genes in combination with protein expression in patients with advanced breast cancer (aBC). The primary purpose was to analyze the prevalence of individual genetic alterations combined with protein expression to define potential targets for an individualized therapy. Between April 2018 and September 2019, 41 patients with aBC were offered a NGS test. The test was used to detect clinically relevant genomic alterations and to support further targeted therapy decisions. Hormone receptors, ERBB2 of tumors and PD-L1 was stained by immunohistochemistry. The data was recorded up to September 2019. After prior consent 41 results were available for further analysis. The most common BC subtypes were triple-negative (n = 16), HR+/ERBB2- (n = 15), and ERBB2+ (n = 9), with one missing data of the primary tumor. 27 patients had more than one genetic alteration. The most common alterations were PIK3CA (n = 14) and ERBB2 alterations (n = 11). Followed by ESR1 (n = 10), FGFR1 (n = 7) and PTEN (n = 7). 68% of the alterations were clinically relevant (tier I and II of ESCAT classification). The most common treatment recommendation was ERBB2-directed therapy (single or double blockade, trastuzumab emtansine and lapatinib) followed by alpelisib in combination with fulvestrant. Comprehensive genomic profiling combined with protein expression analysis in aBC allowed a guided personalized therapy for half of our patients. So far there are no well-defined tools allowing interpretations of genomic alterations detected by NGS in combination with protein expression and other factors.

SARS-CoV-2 infections in cancer outpatients-Most infected patients are asymptomatic carriers without impact on chemotherapy.

Oncologic patients are regarded as the population most at risk of developing a severe course of COVID-19 due to the fact that malignant diseases and chemotherapy often weaken the immune system. In the face of the ongoing SARS-CoV-2 pandemic, how particular patients deal with this infection remains an important question. In the period between the 15 and 26 April 2020, a total of 1227 patients were tested in one of seven oncologic outpatient clinics for SARS-CoV-2, regardless of symptoms, employing RT-qPCR. Of 1227 patients, 78 (6.4%) were tested positive of SARS-CoV-2. Only one of the patients who tested positive developed a severe form of COVID-19 with pneumonia (CURB-65 score of 2), and two patients showed mild symptoms. Fourteen of 75 asymptomatic but positively tested patients received chemotherapy or chemo-immunotherapy according to their regular therapy algorithm (±4 weeks of SARS-CoV-2 test), and 48 of 78 (61.5%) positive-tested patients received glucocorticoids as co-medication. None of the asymptomatic infected patients showed unexpected complications due to the SARS-CoV-2 infection during the cancer treatment. These data clearly contrast the view that patients with an oncologic disease are particularly vulnerable to SARS-CoV-2 and suggest that compromising therapies could be continued or started despite the ongoing pandemic. Moreover the relatively low appearance of symptoms due to COVID-19 among patients on chemotherapy and other immunosuppressive co-medication like glucocorticoids indicate that suppressing the response capacity of the immune system reduces disease severity.

Maximizing the Translational Yield of mRNA Therapeutics by Minimizing 5'-UTRs.

The 5'-untranslated region (5'-UTR) of mRNA contains structural elements, which are recognized by cell-specific RNA-binding proteins, thereby affecting the translation of the molecule. The activation of an innate immune response upon transfection of mRNA into cells is reduced when the mRNA comprises chemically modified nucleotides, putatively by altering the secondary structure of the molecule. Such alteration in the 5'-UTR in turn may affect the functionality of mRNA. In this study, we report on the impact of seven synthetic minimalistic 5'-UTR sequences on the translation of luciferase-encoding unmodified and different chemically modified mRNAs upon transfection in cell culture and in vivo. One minimalistic 5'-UTR, consisting of 14 nucleotides combining the T7 promoter with a Kozak consensus sequence, yielded similar or even higher expression than a 37 nucleotides human alpha-globin 5'-UTR containing mRNA in HepG2 and A549 cells. Furthermore, also the kind of modified nucleotides used in in vitro transcription, affected mRNA translation when using different translation regulators (Kozak vs. translation initiator of short UTRs). The in vitro data were confirmed by bioluminescence imaging of expression in mouse livers, 6 h postintravenous injection of a lipidoid nanoparticle-formulated RNA in female Balb/c mice. Luciferase measurements from liver and spleen showed that minimal 5'-UTRs (3 and 7) were either equally effective or better than human alpha-globin 5'-UTR. These findings were confirmed with a human erythropoietin (hEPO)-encoding mRNA. Significantly, higher levels of hEPO could be quantified in supernatants from A549 cells transfected with minimal 5'-UTR7 containing RNA when compared to commonly used benchmarks 5'-UTRs. Our results demonstrate the superior potential of synthetic minimalistic 5'-UTRs for use in transcript therapies.