Differential functionality of fluoropyrimidine nucleosides for safe cancer therapy.

Chemotherapies are standard care for most cancer types. Pyrimidine analogs including 5-fluorouracil, cytosine arabinoside, 5-azacytidine, and gemcitabine are effective drugs that are utilized as part of a number of anticancer regimens. However, their lack of cell-specificity results in severe side effects. Therefore, there is a capacity to improve the efficacy of such therapies, while decreasing unwanted side effects. Here, we report that while 5-fluorocytosine is not chemotherapeutic in itself, incorporated into a ribonucleoside and more importantly into an RNA oligonucleotide, it induces cytotoxic effects on cancer cells in vitro . Interestingly, these effects are rescued by both uridine and thymidine. Similarly, in-vitro 2'-deoxy-5-fluorocytidine inhibits the growth of tumor cells but has the advantage of being less toxic to human primary cells compared with 5-fluorocytidine, suggesting that the deoxyribonucleoside could exhibit less side-effects in vivo . Thus, this work indicates that the potency of 5-fluorocytidine and 2'-deoxy-5-fluorocytidine should be further explored. In particular, oligonucleotides incorporating 5-fluorocytosine could be novel chemotherapeutic drugs that could be formulated in cancer-specific particles for safe and efficacious cancer treatments.

Design and Synthesis of Circular RNA Expression Vectors.

The recent success of the synthetic mRNA-based anti-COVID-19 vaccines has demonstrated the broad potential of the mRNA platform for applications in medicine, thanks to the combined efforts of a small community that has vastly improved key determinants such as design and formulation of synthetic mRNA during the past three decades. However, the cost of production and sensitivity to enzymatic degradation are still limiting the broader application of synthetic mRNA for therapeutic applications. The increased interest in mRNA-based technologies has spurred a renaissance for circular RNA (circRNA), as the lack of free 5' and 3' ends substantially increases resistance against enzymatic degradation in biological systems and does not require expensive cap analogs, as translation is controlled by an Internal Ribosome Entry Site (IRES) sequence. Thus, it can be expected that circRNA will play an important role for future mRNA therapeutics. Here we provide a detailed guide to the production of synthetic circRNA.

A Basic Method for Formulating mRNA-Lipid Nanoparticle Vaccines in the Lab.

During recent years, RNA therapeutics have begun to make a substantial impact in the clinic, with the approval of the siRNA-based therapeutic Patisiran in 2018, and of the two mRNA SARS-CoV-2 vaccines, BNT162b2 and mRNA-1273 in 2021. A key to the success of these therapeutics lies in the lipid-based delivery system. The therapeutic RNAs are encapsulated in lipid nanoparticles (LNPs), which protect against enzymatic degradation and efficiently deliver the RNA across the cell membrane into the cytosol. Thereby, the method used for LNP synthesis and its lipid composition are crucial aspects that decide the efficacy of the LNP-RNA hetero system. Here we provide a detailed guide for the simple preparation of LNP-encapsulated mRNA vaccines.

Synthetic mRNAs Containing Minimalistic Untranslated Regions Are Highly Functional In Vitro and In Vivo.

Synthetic mRNA produced by in vitro transcription (ivt mRNA) is the active pharmaceutical ingredient of approved anti-COVID-19 vaccines and of many drugs under development. Such synthetic mRNA typically contains several hundred bases of non-coding "untranslated" regions (UTRs) that are involved in the stabilization and translation of the mRNA. However, UTRs are often complex structures, which may complicate the entire production process. To eliminate this obstacle, we managed to reduce the total amount of nucleotides in the UTRs to only four bases. In this way, we generate minimal ivt mRNA ("minRNA"), which is less complex than the usual optimized ivt mRNAs that are contained, for example, in approved vaccines. We have compared the efficacy of minRNA to common augmented mRNAs (with UTRs of globin genes or those included in licensed vaccines) in vivo and in vitro and could demonstrate equivalent functionalities. Our minimal mRNA design will facilitate the further development and implementation of ivt mRNA-based vaccines and therapies.

The Pediatric Autism Research Cohort (PARC) Study: protocol for a patient-oriented prospective study examining trajectories of functioning in children with autism.

INTRODUCTION: The developmentally variable nature of autism poses challenges in providing timely services tailored to a child's needs. Despite a recent focus on longitudinal research, priority-setting initiatives with stakeholders highlighted the importance of studying a child's day-to-day functioning and social determinants of health to inform clinical care. To address this, we are conducting a pragmatic multi-site, patient-oriented longitudinal investigation: the Pediatric Autism Research Cohort (PARC) Study. In young children (<7 years of age) newly diagnosed with autism, we will: (1) examine variability in trajectories of adaptive functioning from the point of diagnosis into transition to school; and (2) identify factors associated with trajectories of adaptive functioning. METHODS AND ANALYSIS: We aim to recruit 1300 children under 7 years of age with a recent (within 12 months) diagnosis of autism from seven sites: six in Canada; one in Israel. Participants will be followed prospectively from diagnosis to age 8 years, with assessments at 6-month intervals. Parents/caregivers will complete questionnaires administered via a customized online research portal. Following each assessment timepoint, families will receive a research summary report describing their child's progress on adaptive functioning and related domains. Analysis of the longitudinal data will map trajectories and examine child, family and service characteristics associated with chronogeneity (interindividual and intraindividual heterogeneity over time) and possible trajectory turning points around sensitive periods like the transition to school. ETHICS AND DISSEMINATION: Ethics approvals have been received by all sites. All parents/respondents will provide informed consent when enrolling in the study. Using an integrated knowledge translation approach, where stakeholders are directly engaged in the research process, the PARC Study will identify factors associated with trajectories of functioning in children with autism. Resulting evidence will be shared with government policy makers to inform provincial and national programs. Findings will be disseminated at conferences and published in peer-reviewed journals.

The Family-Check-Up® Autism Implementation Research (FAIR) Study: protocol for a study evaluating the effectiveness and implementation of a family-centered intervention within a Canadian autism service setting.

Introduction: Prevalence rates of emotional and behavior problems (EBP) in autistic children and youth are high (40-70%), and often cause severe and chronic impairment. Furthermore, autistic children are also more likely to experience family "social-ecological" adversity compared to neurotypically developing peers, including social isolation, child maltreatment, caregiver mental illness, and socioeconomic risk. These family stressors increase the risk of co-occurring EBP among autistic children and can often impede access to evidence-based care, thus amplifying long-term health inequities for autistic children and their caregivers. In the current autism services landscape, there are few scalable, evidence-based programs that adequately address these needs. The Family Check-Up (FCU®) is a brief, strength-based, and tailored family-centered intervention that supports positive parenting and explicitly assesses the social determinants of child and family mental health within an ecological framework. Studies have demonstrated long-term positive child and caregiver outcomes in other populations, but the FCU® has not been evaluated in families of autistic children and youth. Therefore, we aimed to evaluate FCU® implementation within an established, publicly funded Autism Program in Ontario, Canada, with delivery by autism therapists, to demonstrate sustainable effectiveness within real-world settings. Methods: In this study, we outline the protocol for a hybrid implementation-effectiveness approach with two key components: (1) A parallel-arm randomized controlled trial of N = 80 autistic children/youth (ages 6-17 years) and high levels of EBP and their caregivers. Primary and secondary outcomes include child EBP, and caregiver well-being and parenting. (2) A mixed methods implementation study, to describe facilitators and barriers to implementation of the FCU® within an autism service setting. Discussion: Scalable, ecologically focused family-centered interventions offer promise as key components of a public health framework aimed at reducing mental health inequities among autistic children, youth, and their caregivers. Results of this study will inform further program refinement and scale-up.