Cytidine Deaminase Resolves Replicative Stress and Protects Pancreatic Cancer from DNA-Targeting Drugs.

Cytidine deaminase (CDA) functions in the pyrimidine salvage pathway for DNA and RNA syntheses and has been shown to protect cancer cells from deoxycytidine-based chemotherapies. In this study, we observed that CDA was overexpressed in pancreatic adenocarcinoma from patients at baseline and was essential for experimental tumor growth. Mechanistic investigations revealed that CDA localized to replication forks where it increased replication speed, improved replication fork restart efficiency, reduced endogenous replication stress, minimized DNA breaks, and regulated genetic stability during DNA replication. In cellular pancreatic cancer models, high CDA expression correlated with resistance to DNA-damaging agents. Silencing CDA in patient-derived primary cultures in vitro and in orthotopic xenografts in vivo increased replication stress and sensitized pancreatic adenocarcinoma cells to oxaliplatin. This study sheds light on the role of CDA in pancreatic adenocarcinoma, offering insights into how this tumor type modulates replication stress. These findings suggest that CDA expression could potentially predict therapeutic efficacy and that targeting CDA induces intolerable levels of replication stress in cancer cells, particularly when combined with DNA-targeted therapies. SIGNIFICANCE: Cytidine deaminase reduces replication stress and regulates DNA replication to confer resistance to DNA-damaging drugs in pancreatic cancer, unveiling a molecular vulnerability that could enhance treatment response.

Olaparib for adjuvant treatment of BRCA mutation-positive HER2-negative high-risk early breast cancer after chemotherapy

People with BRCA mutation-positive HER2­negative high-risk early breast cancer usually have chemotherapy followed by surgery (neoadjuvant chemotherapy), or surgery followed by chemotherapy (adjuvant chemotherapy). Clinical trial evidence shows that, compared with placebo, olaparib after neoadjuvant or adjuvant chemotherapy decreases the chance of the cancer returning or getting worse, and increases the length of time people live. The cost-effectiveness estimates for olaparib are within what NICE considers to be an acceptable use of NHS resources. So, olaparib is recommended.

Brincidofovir y cidofovir para viruela símica / Brincidofovir and cidofovir for smallpox seismic

INTRODUÇÃO: Brincidofovir es un profármaco y un inhibidor de la polimerasa de ADN análogo de nucleótido de ortopoxvirus que se convierte intracelularmente en el análogo de nucleótido cidofovir, que se fosforila a difosfato de cidofovir, la fracción activa que tiene actividad antiviral contra el virus de la viruela. La incorporación de cidofovir en la cadena de ADN viral en crecimiento da como resultado reducciones en la tasa de síntesis de ADN viral. Se administra por vía oral en comprimidos o suspensión oral a 200 mg una vez a la semana en dos dosis para personas con 48 kg o más, mientras que para personas de 10 a 48 kg la suspensión oral se administra a 4 mg/kg una vez a la semana en dos dosis. La Administración de Alimentos y Medicamentos (FDA, su sigla del inglés Food and Drug Administration) de los Estados Unidos y la Agencia Europea de Medicamentos (EMA, su sigla del inglés European Medicines Agency) han autorizado para el año 2021 la comercialización brincidofovir (TEMBEXA®) para el tratamiento de la viruela, sin embargo, todavía no han ampliado su indicación a viruela símica. OBJETIVO: El objetivo del presente informe es evaluar parámetros de eficacia, seguridad, conveniencia y recomendaciones disponibles acerca del empleo de brincidofovir y cidofovir para el tratamiento de personas con viruela símica en Argentina. MÉTODOS: Teniendo en cuenta la velocidad con la que la información relacionada a la epidemia aparece y se modifica, se desarrollará un protocolo sustentado en proyectos que resume activamente la evidencia científica a medida que la misma se hace disponible. Desarrollaremos una síntesis de evidencia viva, dado el contexto actual de producción de la evidencia y necesidad actualizada de información de calidad para la toma de decisiones en salud.13,14 Con este fin se utilizará la plataforma L-ove de Epistemonikos (https://app.iloveevidence.com/topics) para identificar revisiones sistemáticas "vivas". Se seleccionarán aquellas con una calidad metodológica apropiada evaluada a través de la herramienta AMSTAR-2, y que a su vez llevaran un proceso de actualización frecuente. De cada una de las revisiones sistemáticas vivas identificadas se extractarán los efectos de la intervención sobre los desenlaces priorizados como importantes o críticos y la certeza en dichos efectos. Para la priorización de los desenlaces se adoptará una perspectiva desde el paciente considerando sus potenciales preferencias. La selección se realizará por consenso entre los autores y supervisores del informe considerando los protocolos de ensayos clínicos registrados y publicados, y las cohortes de pacientes con viruela símica. Se seleccionaron "mortalidad", "hospitalización", "mejoría clínica" (tiempo hasta la mejoría subjetiva, aparición de nuevas lesiones, todas las lesiones con costra y una capa de piel sana), "eventos adversos graves" como desenlaces críticos e importantes. Adicionalmente, se extractarán datos relacionados con efectos de subgrupo potencialmente relevantes para la toma de decisión, con especial énfasis en el tiempo de evolución, la severidad de la enfermedad y el estado inmunológico. Para confeccionar las conclusiones en el efecto de las intervenciones evaluadas sobre los desenlaces priorizados, utilizamos lineamientos publicados, específicamente desarrollados a tal fin. RECOMENDACIONES: Para la identificación de recomendaciones sustentadas en evidencia y actualizadas, se utilizarán motores de búsqueda de recomendaciones y directrices basadas en evidencia: ACCESSSS, ECRI, BIGG Database, MAGIC authoring and publication platform (MAGICapp), BIGG-REC, National Institute for Health and Clinical Excellence (NICE), National Guideline Clearinghouse (NGC), New Zealand Guidelines Group (NZGG), Scottish Intercollegiate Guidelines Network (SIGN), American College of Physicians (ACP), Association of the Scientific Medical Societies in Germany (AWMF) Guidelines Register, Institute for Clinical Systems Improvement (ICSI), Canadian Medical Association (CMA), GuiaSalud. Se seleccionarán aquellas guías con rigor metodológico apropiado (Dominios 3 y 4 según la herramienta AGREE II => 60%) y se incorporaron sus recomendaciones al informe. RESULTADOS: Se identificó una revisión sistemática que cumplió con los criterios de inclusión del presente informe y reportó resultados: Se identificó 1 ECA registrado en fase 1 que evalúa el uso de brincidofovir endovenoso. Las tecnologías no están autorizadas para su comercialización en Argentina y no se encuentran disponible al momento de la realización del presente informe. No se halló información relacionada con valores y preferencias de las personas con viruela símica. CONCLUSIONES: No se halló evidencia que permita evaluar los efectos en la salud relacionados con el empleo de brincidofovir y cidofovir en pacientes expuestos o con viruela símica. Las tecnologías no están autorizadas para su comercialización por la Administración Nacional de Medicamentos, Alimentos y Tecnología Médica de nuestro país al momento de la fecha de realización del presente informe. Se estima que brincidofovir y cidofovir cumplen criterios para ser utilizados en el marco del uso de emergencia monitoreado de intervenciones no registradas y experimentales (MEURI). No se identificaron guías de práctica clínica de adecuada calidad metodológica actualizadas que mencionen las tecnologías en la indicación evaluada.

A Case Report of Successful Use of Twice-Daily Letermovir in the Treatment of Resistant Cytomegalovirus in a Small Bowel Transplant Recipient.

Cytomegalovirus (CMV) is considered one of the most notable pathogens that affect patients after solid organ transplantation (SOT), especially small bowel transplant patients with a risk of high mortality rate. Its management relies historically on the use of CMV DNA polymerase inhibitors (namely, ganciclovir and valganciclovir). Second-line options include foscarnet and cidofovir, which are highly nephrotoxic and thus less preferred and only used in ganciclovir intolerance or resistance cases. Letermovir is a novel antiviral agent approved for CMV prophylaxis in hematopoietic stem cell transplant, but not for SOT (neither for prophylaxis nor for treatment). We report the first case on the successful use of letermovir in treating CMV disease in a small bowel transplant patient who failed to achieve viral clearance due to ganciclovir resistance and severe intolerance to foscarnet.

Durvalumab with platinum-pemetrexed for unresectable pleural mesothelioma: survival, genomic and immunologic analyses from the phase 2 PrE0505 trial.

Mesothelioma is a rare and fatal cancer with limited therapeutic options until the recent approval of combination immune checkpoint blockade. Here we report the results of the phase 2 PrE0505 trial ( NCT02899195 ) of the anti-PD-L1 antibody durvalumab plus platinum-pemetrexed chemotherapy for 55 patients with previously untreated, unresectable pleural mesothelioma. The primary endpoint was overall survival compared to historical control with cisplatin and pemetrexed chemotherapy; secondary and exploratory endpoints included safety, progression-free survival and biomarkers of response. The combination of durvalumab with chemotherapy met the pre-specified primary endpoint, reaching a median survival of 20.4 months versus 12.1 months with historical control. Treatment-emergent adverse events were consistent with known side effects of chemotherapy, and all adverse events due to immunotherapy were grade 2 or lower. Integrated genomic and immune cell repertoire analyses revealed that a higher immunogenic mutation burden coupled with a more diverse T cell repertoire was linked to favorable clinical outcome. Structural genome-wide analyses showed a higher degree of genomic instability in responding tumors of epithelioid histology. Patients with germline alterations in cancer predisposing genes, especially those involved in DNA repair, were more likely to achieve long-term survival. Our findings indicate that concurrent durvalumab with platinum-based chemotherapy has promising clinical activity and that responses are driven by the complex genomic background of malignant pleural mesothelioma.

Polymerase θ Coordinates Multiple Intrinsic Enzymatic Activities during DNA Repair.

The POLQ gene encodes DNA polymerase θ, a 2590 amino acid protein product harboring DNA-dependent ATPase, template-dependent DNA polymerase, dNTP-dependent endonuclease, and 5'-dRP lyase functions. Polymerase θ participates at an essential step of a DNA double-strand break repair pathway able to join 5'-resected substrates by locating and pairing microhomologies present in 3'-overhanging single-stranded tails, cleaving the extraneous 3'-DNA by dNTP-dependent end-processing, before extending the nascent 3' end from the microhomology annealing site. Metazoans require polymerase θ for full resistance to DNA double-strand break inducing agents but can survive knockout of the POLQ gene. Cancer cells with compromised homologous recombination, or other DNA repair defects, over-utilize end-joining by polymerase θ and often over-express the POLQ gene. This dependency points to polymerase θ as an ideal drug target candidate and multiple drug-development programs are now preparing to enter clinical trials with small-molecule inhibitors. Specific inhibitors of polymerase θ would not only be predicted to treat BRCA-mutant cancers, but could thwart accumulated resistance to current standard-of-care cancer therapies and overcome PARP-inhibitor resistance in patients. This article will discuss synthetic lethal strategies targeting polymerase θ in DNA damage-response-deficient cancers and summarize data, describing molecular structures and enzymatic functions.

Chronic Hepatitis B Treatment Strategies Using Polymerase Inhibitor-Based Combination Therapy.

Viral polymerase is an essential enzyme for the amplification of the viral genome and is one of the major targets of antiviral therapies. However, a serious concern to be solved in hepatitis B virus (HBV) infection is the difficulty of eliminating covalently closed circular (ccc) DNA. More recently, therapeutic strategies targeting various stages of the HBV lifecycle have been attempted. Although cccDNA-targeted therapies are attractive, there are still many problems to be overcome, and the development of novel polymerase inhibitors remains an important issue. Interferons and nucleos(t)ide reverse transcriptase inhibitors (NRTIs) are the only therapeutic options currently available for HBV infection. Many studies have reported that the combination of interferons and NRTI causes the loss of hepatitis B surface antigen (HBsAg), which is suggestive of seroconversion. Although NRTIs do not directly target cccDNA, they can strongly reduce the serum viral DNA load and could suppress the recycling step of cccDNA formation, improve liver fibrosis/cirrhosis, and reduce the risk of hepatocellular carcinoma. Here, we review recent studies on combination therapies using polymerase inhibitors and discuss the future directions of therapeutic strategies for HBV infection.

C60 fullerene against SARS-CoV-2 coronavirus: an in silico insight.

Based on WHO reports the new SARS-CoV-2 coronavirus is currently widespread all over the world. So far > 162 million cases have been confirmed, including > 3 million deaths. Because of the pandemic still spreading across the globe the accomplishment of computational methods to find new potential mechanisms of virus inhibitions is necessary. According to the fact that C60 fullerene (a sphere-shaped molecule consisting of carbon) has shown inhibitory activity against various protein targets, here the analysis of the potential binding mechanism between SARS-CoV-2 proteins 3CLpro and RdRp with C60 fullerene was done; it has resulted in one and two possible binding mechanisms, respectively. In the case of 3CLpro, C60 fullerene interacts in the catalytic binding pocket. And for RdRp in the first model C60 fullerene blocks RNA synthesis pore and in the second one it prevents binding with Nsp8 co-factor (without this complex formation, RdRp can't perform its initial functions). Then the molecular dynamics simulation confirmed the stability of created complexes. The obtained results might be a basis for other computational studies of 3CLPro and RdRp potential inhibition ways as well as the potential usage of C60 fullerene in the fight against COVID-19 disease.

Current Drugs to Treat Infections with Herpes Simplex Viruses-1 and -2.

Herpes simplex viruses-1 and -2 (HSV-1 and -2) are two of the three human alphaherpesviruses that cause infections worldwide. Since both viruses can be acquired in the absence of visible signs and symptoms, yet still result in lifelong infection, it is imperative that we provide interventions to keep them at bay, especially in immunocompromised patients. While numerous experimental vaccines are under consideration, current intervention consists solely of antiviral chemotherapeutic agents. This review explores all of the clinically approved drugs used to prevent the worst sequelae of recurrent outbreaks by these viruses.

Influenza Therapeutics in Clinical Practice-Challenges and Recent Advances.

In the last few years, several new direct-acting influenza antivirals have been licensed, and others have advanced in clinical development. The increasing diversity of antiviral classes should allow an adequate public health response should a resistant virus to one agent or class widely circulate. One new antiviral, baloxavir marboxil, has been approved in the United States for treatment of influenza in those at high risk of developing influenza-related complications. Except for intravenous zanamivir in European Union countries, no antivirals have been licensed specifically for the indication of severe influenza or hospitalized influenza. This review addresses recent clinical developments involving selected polymerase inhibitors, neuraminidase inhibitors, antibody-based therapeutics, and host-directed therapies. There are many knowledge gaps for most of these agents because some data are not published and multiple pivotal studies are in progress at present. This review also considers important clinical research issues, including regulatory pathways, study designs, endpoints, and target populations encountered during the clinical development of novel therapeutics.

Targeting the DNA Repair Enzyme Polymerase θ in Cancer Therapy.

Targeted cancer therapies represent a milestone towards personalized treatment as they function via inhibition of cancer-specific alterations. Polymerase θ (POLQ), an error-prone translesion polymerase, also involved in DNA double-strand break (DSB) repair, is often upregulated in cancer. POLQ is synthetic lethal with various DNA repair genes, including known cancer drivers such as BRCA1/2, making it essential in homologous recombination-deficient cancers. Thus, POLQ represents a promising target in cancer therapy and efforts for the development of POLQ inhibitors are actively underway with first clinical trials due to start in 2021. This review summarizes the journey of POLQ from a backup DNA repair enzyme to a promising therapeutic target for cancer treatment.

DNA polymerase eta: A potential pharmacological target for cancer therapy.

In the last two decades, intensive research has been carried out to improve the survival rates of cancer patients. However, the development of chemoresistance that ultimately leads to tumor relapse poses a critical challenge for the successful treatment of cancer patients. Many cancer patients experience tumor relapse and ultimately die because of treatment failure associated with acquired drug resistance. Cancer cells utilize multiple lines of self-defense mechanisms to bypass chemotherapy and radiotherapy. One such mechanism employed by cancer cells is translesion DNA synthesis (TLS), in which specialized TLS polymerases bypass the DNA lesion with the help of monoubiquitinated proliferating cell nuclear antigen. Among all TLS polymerases (Pol η, Pol ι, Pol κ, REV1, Pol ζ, Pol µ, Pol λ, Pol ν, and Pol θ), DNA polymerase eta (Pol η) is well studied and majorly responsible for the bypass of cisplatin and UV-induced DNA damage. TLS polymerases contribute to chemotherapeutic drug-induced mutations as well as therapy resistance. Therefore, targeting these polymerases presents a novel therapeutic strategy to combat chemoresistance. Mounting evidence suggests that inhibition of Pol η may have multiple impacts on cancer therapy such as sensitizing cancer cells to chemotherapeutics, suppressing drug-induced mutagenesis, and inhibiting the development of secondary tumors. Herein, we provide a general introduction of Pol η and its clinical implications in blocking acquired drug resistance. In addition; this review addresses the existing gaps and challenges of Pol η mediated TLS mechanisms in human cells. A better understanding of the Pol η mediated TLS mechanism will not merely establish it as a potential pharmacological target but also open possibilities to identify novel drug targets for future therapy.

Translesion DNA Synthesis and Reinitiation of DNA Synthesis in Chemotherapy Resistance.

Many chemotherapy drugs block tumor cell division by damaging DNA. DNA polymerases eta (Pol η), iota (Pol ι), kappa (Pol κ), REV1 of the Y-family and zeta (Pol ζ) of the B-family efficiently incorporate nucleotides opposite a number of DNA lesions during translesion DNA synthesis. Primase-polymerase PrimPol and the Pol α-primase complex reinitiate DNA synthesis downstream of the damaged sites using their DNA primase activity. These enzymes can decrease the efficacy of chemotherapy drugs, contribute to the survival of tumor cells and to the progression of malignant diseases. DNA polymerases are promising targets for increasing the effectiveness of chemotherapy, and mutations and polymorphisms in some DNA polymerases can serve as additional prognostic markers in a number of oncological disorders.

Efficacy of BCG vaccine and Mitomycin C for the treatment of ocular squamous cell carcinoma in bovines.

Bovine ocular squamous cell carcinoma (BOSCC) also called cancer eye, represents the most economically important neoplasm in large animals. Hereditary factors, environmental factors, lack of eyelid pigmentation, age and dietary habits have all been reported to play a role in the etiopathogenesis of bovine ocular squamous cell carcinoma. In group I, six animals with small, localized eye cancer where vision was not affected were included and subjected to intralesional injection of Bacillus Calmette- Guerin (BCG) vaccine at 0, 14, 35, and 56 days interval. In group II (six animals), surgical excision and Mitomycin C 0.04% topically on alternate weeks for two months as adjunctive therapy. All the animals recovered completely with no recurrence for a follow up period of one year.

Advances and challenges in the prevention and treatment of COVID-19.

Since the end of 2019, a new type of coronavirus pneumonia (COVID-19) caused by the Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2) has been spreading rapidly throughout the world. Previously, there were two outbreaks of severe coronavirus caused by different coronaviruses worldwide, namely Severe Acute Respiratory Syndrome Coronavirus (SARS-CoV) and the Middle East Respiratory Syndrome Coronavirus (MERS-CoV). This article introduced the origin, virological characteristics and epidemiological overview of SARS-CoV-2, reviewed the currently known drugs that may prevent and treat coronavirus, explained the characteristics of the new coronavirus and provided novel information for the prevention and treatment of COVID-19.

Potential therapeutic targets and promising drugs for combating SARS-CoV-2.

As of April 9, 2020, a novel coronavirus (SARS-CoV-2) had caused 89,931 deaths and 1,503,900 confirmed cases worldwide, which indicates an increasingly severe and uncontrollable situation. Initially, little was known about the virus. As research continues, we now know the genome structure, epidemiological and clinical characteristics, and pathogenic mechanisms of SARS-CoV-2. Based on this knowledge, potential targets involved in the processes of virus pathogenesis need to be identified, and the discovery or development of drugs based on these potential targets is the most pressing need. Here, we have summarized the potential therapeutic targets involved in virus pathogenesis and discuss the advances, possibilities, and significance of drugs based on these targets for treating SARS-CoV-2. This review will facilitate the identification of potential targets and provide clues for drug development that can be translated into clinical applications for combating SARS-CoV-2.

Poly(ADP-ribose) polymerase inhibitors in prostate and urothelial cancer.

PURPOSE OF REVIEW: The aim of this article is to give an overview of poly(ADP-ribose) polymerase inhibitors (PARPis) trials in prostate cancer and to discuss emerging approaches with potential future clinical implementation in both prostate and urothelial cancer. RECENT FINDINGS: PARPis are a class of drugs that can be applied for the treatment of homologous recombination repair (HRR)-deficient tumors. Tumors are potentially sensitive to PARPi harbor mutations in genes relevant for DNA damage repair, such as BRCA1/2 or ATM, which are present to a significant degree in metastatic prostate and urothelial cancer patients. Several PARPis have been successfully tested in clinical trials for HRR-deficient metastatic castration-resistant prostate cancer (mCRPC), and olaparib and rucaparib have recently received breakthrough approval in BRCA1/2 mutated mCRPC. Combination treatment of PARPis with androgen-receptor inhibitors or with checkpoint inhibitors and earlier frontline applications are currently being evaluated, and clinical trials enrolling bladder cancer (BCa) patients with HRR deficiency have recently been initiated. SUMMARY: Approximately 10% of mCRPC patients and 34% of metastatic BCa patients have tumors with HRR deficiency and may benefit from PARPi treatment. Correct identification of these patients as well as determining the most adequate time point for drug administration will be key to successful clinical implementation.

Peptides containing the PCNA interacting motif APIM bind to the ß-clamp and inhibit bacterial growth and mutagenesis.

In the fight against antimicrobial resistance, the bacterial DNA sliding clamp, ß-clamp, is a promising drug target for inhibition of DNA replication and translesion synthesis. The ß-clamp and its eukaryotic homolog, PCNA, share a C-terminal hydrophobic pocket where all the DNA polymerases bind. Here we report that cell penetrating peptides containing the PCNA-interacting motif APIM (APIM-peptides) inhibit bacterial growth at low concentrations in vitro, and in vivo in a bacterial skin infection model in mice. Surface plasmon resonance analysis and computer modeling suggest that APIM bind to the hydrophobic pocket on the ß-clamp, and accordingly, we find that APIM-peptides inhibit bacterial DNA replication. Interestingly, at sub-lethal concentrations, APIM-peptides have anti-mutagenic activities, and this activity is increased after SOS induction. Our results show that although the sequence homology between the ß-clamp and PCNA are modest, the presence of similar polymerase binding pockets in the DNA clamps allows for binding of the eukaryotic binding motif APIM to the bacterial ß-clamp. Importantly, because APIM-peptides display both anti-mutagenic and growth inhibitory properties, they may have clinical potential both in combination with other antibiotics and as single agents.

Coronavirus Infections in Children Including COVID-19: An Overview of the Epidemiology, Clinical Features, Diagnosis, Treatment and Prevention Options in Children.

Coronaviruses (CoVs) are a large family of enveloped, single-stranded, zoonotic RNA viruses. Four CoVs commonly circulate among humans: HCoV2-229E, -HKU1, -NL63 and -OC43. However, CoVs can rapidly mutate and recombine leading to novel CoVs that can spread from animals to humans. The novel CoVs severe acute respiratory syndrome coronavirus (SARS-CoV) emerged in 2002 and Middle East respiratory syndrome coronavirus (MERS-CoV) in 2012. The 2019 novel coronavirus (SARS-CoV-2) is currently causing a severe outbreak of disease (termed COVID-19) in China and multiple other countries, threatening to cause a global pandemic. In humans, CoVs mostly cause respiratory and gastrointestinal symptoms. Clinical manifestations range from a common cold to more severe disease such as bronchitis, pneumonia, severe acute respiratory distress syndrome, multi-organ failure and even death. SARS-CoV, MERS-CoV and SARS-CoV-2 seem to less commonly affect children and to cause fewer symptoms and less severe disease in this age group compared with adults, and are associated with much lower case-fatality rates. Preliminary evidence suggests children are just as likely as adults to become infected with SARS-CoV-2 but are less likely to be symptomatic or develop severe symptoms. However, the importance of children in transmitting the virus remains uncertain. Children more often have gastrointestinal symptoms compared with adults. Most children with SARS-CoV present with fever, but this is not the case for the other novel CoVs. Many children affected by MERS-CoV are asymptomatic. The majority of children infected by novel CoVs have a documented household contact, often showing symptoms before them. In contrast, adults more often have a nosocomial exposure. In this review, we summarize epidemiologic, clinical and diagnostic findings, as well as treatment and prevention options for common circulating and novel CoVs infections in humans with a focus on infections in children.