Physiologically Based Biopharmaceutics Modeling (PBBM): Best Practices for Drug Product Quality, Regulatory and Industry Perspectives: 2023 Workshop Summary Report.

Physiologically based biopharmaceutics modeling (PBBM) is used to elevate drug product quality by providing a more accurate and holistic understanding of how drugs interact with the human body. These models are based on the integration of physiological, pharmacological, and pharmaceutical data to simulate and predict drug behavior in vivo. Effective utilization of PBBM requires a consistent approach to model development, verification, validation, and application. Currently, only one country has a draft guidance document for PBBM, whereas other major regulatory authorities have had limited experience with the review of PBBM. To address this gap, industry submitted confidential PBBM case studies to be reviewed by the regulatory agencies; software companies committed to training. PBBM cases were independently and collaboratively discussed by regulators, and academic colleagues participated in some of the discussions. Successful bioequivalence "safe space" industry case examples are also presented. Overall, six regulatory agencies were involved in the case study exercises, including ANVISA, FDA, Health Canada, MHRA, PMDA, and EMA (experts from Belgium, Germany, Norway, Portugal, Spain, and Sweden), and we believe this is the first time such a collaboration has taken place. The outcomes were presented at this workshop, together with a participant survey on the utility and experience with PBBM submissions, to discuss the best scientific practices for developing, validating, and applying PBBMs. The PBBM case studies enabled industry to receive constructive feedback from global regulators and highlighted clear direction for future PBBM submissions for regulatory consideration.

Parameterization of Physiologically Based Biopharmaceutics Models: Workshop Summary Report.

This Article shares the proceedings from the August 29th, 2023 (day 1) workshop "Physiologically Based Biopharmaceutics Modeling (PBBM) Best Practices for Drug Product Quality: Regulatory and Industry Perspectives". The focus of the day was on model parametrization; regulatory authorities from Canada, the USA, Sweden, Belgium, and Norway presented their views on PBBM case studies submitted by industry members of the IQ consortium. The presentations shared key questions raised by regulators during the mock exercise, regarding the PBBM input parameters and their justification. These presentations also shed light on the regulatory assessment processes, content, and format requirements for future PBBM regulatory submissions. In addition, the day 1 breakout presentations and discussions gave the opportunity to share best practices around key questions faced by scientists when parametrizing PBBMs. Key questions included measurement and integration of drug substance solubility for crystalline vs amorphous drugs; impact of excipients on apparent drug solubility/supersaturation; modeling of acid-base reactions at the surface of the dissolving drug; choice of dissolution methods according to the formulation and drug properties with a view to predict the in vivo performance; mechanistic modeling of in vitro product dissolution data to predict in vivo dissolution for various patient populations/species; best practices for characterization of drug precipitation from simple or complex formulations and integration of the data in PBBM; incorporation of drug permeability into PBBM for various routes of uptake and prediction of permeability along the GI tract.

Probing the interaction between the histone methyltransferase/deacetylase subunit RBBP4/7 and the transcription factor BCL11A in epigenetic complexes.

The transcription factor BCL11A has recently been reported to be a driving force in triple-negative breast cancer (TNBC), contributing to the maintenance of a chemoresistant breast cancer stem cell (BCSC) population. Although BCL11A was shown to suppress γ-globin and p21 and to induce MDM2 expression in the hematopoietic system, its downstream targets in TNBC are still unclear. For its role in transcriptional repression, BCL11A was found to interact with several corepressor complexes; however, the mechanisms underlying these interactions remain unknown. Here, we reveal that BCL11A interacts with histone methyltransferase (PRC2) and histone deacetylase (NuRD and SIN3A) complexes through their common subunit, RBBP4/7. In fluorescence polarization assays, we show that BCL11A competes with histone H3 for binding to the negatively charged top face of RBBP4. To define that interaction, we solved the crystal structure of RBBP4 in complex with an N-terminal peptide of BCL11A (residues 2-16, BCL11A(2-16)). The crystal structure identifies novel interactions between BCL11A and the side of the ß-propeller of RBBP4 that are not seen with histone H3. We next show that BCL11A(2-16) pulls down RBBP4, RBBP7, and other components of PRC2, NuRD, and SIN3A from the cell lysate of the TNBC cell line SUM149. Furthermore, we demonstrate the therapeutic potential of targeting the RBBP4-BCL11A binding by showing that a BCL11A peptide can decrease aldehyde dehydrogenase-positive BCSCs and mammosphere formation capacity in SUM149. Together, our findings have uncovered a previously unidentified mechanism that BCL11A may use to recruit epigenetic complexes to regulate transcription and promote tumorigenesis.

Drug Dissolution in Oral Drug Absorption: Workshop Report.

The in-person workshop "Drug Dissolution in Oral Drug Absorption" was held on May 23-24, 2023, in Baltimore, MD, USA. The workshop was organized into lectures and breakout sessions. Three common topics that were re-visited by various lecturers were amorphous solid dispersions (ASDs), dissolution/permeation interplay, and in vitro methods to predict in vivo biopharmaceutics performance and risk. Topics that repeatedly surfaced across breakout sessions were the following: (1) meaning and assessment of "dissolved drug," particularly of poorly water soluble drug in colloidal environments (e.g., fed conditions, ASDs); (2) potential limitations of a test that employs sink conditions for a poorly water soluble drug; (3) non-compendial methods (e.g., two-stage or multi-stage method, dissolution/permeation methods); (4) non-compendial conditions (e.g., apex vessels, non-sink conditions); and (5) potential benefit of having both a quality control method for batch release and a biopredictive/biorelevant method for biowaiver or bridging scenarios. An identified obstacle to non-compendial methods is the uncertainty of global regulatory acceptance of such methods.

Doxycycline targets aldehyde dehydrogenase­positive breast cancer stem cells.

Targeting cancer stem cells (CSCs) is a key strategy to prevent cancers from developing drug resistance and metastasis. Mitochondria have been reported to be a vulnerability of CSCs by multiple studies. Here, we report that doxycycline, functioning as an inhibitor of mitochondrial biogenesis, can effectively target breast cancer stem cells (BCSCs). Our results revealed that doxycycline significantly decreased the frequency of aldehyde dehydrogenase­positive (ALDH+) BCSCs as well as mammosphere formation efficiency in HER2+ and triple­negative breast cancer (TNBC) subtypes. Doxycycline also ameliorated paclitaxel­induced enrichment of ALDH+ BCSCs in TNBC. Mechanistically, we showed that doxycycline decreased the level of reactive oxygen species and their downstream p38 MAPK pathway. In agreement with the key role for p38 in maintaining BCSCs, a specific inhibitor targeting this MAPK pathway significantly decreased the number of ALDH+ cells. Doxycycline is a FDA­approved drug with minor and limited side­effects. Given doxycycline's low toxicity and strong effect on BCSC inhibition, we report that doxycycline should be safe to be used concomitantly with chemotherapy drugs to eradicate both CSCs and bulk tumor cells.

Targeting LRP8 inhibits breast cancer stem cells in triple-negative breast cancer.

Triple-negative breast cancer (TNBC) is the most difficult subtype of breast cancer to treat due to a paucity of effective targeted therapies. Many studies have reported that breast cancer stem cells (BCSCs) are enriched in TNBC and are responsible for chemoresistance and metastasis. In this study, we identify LRP8 as a novel positive regulator of BCSCs in TNBC. LRP8 is highly expressed in TNBC compared to other breast cancer subtypes and its genomic locus is amplified in 24% of TNBC tumors. Knockdown of LRP8 in TNBC cell lines inhibits Wnt/ß-catenin signaling, decreases BCSCs, and suppresses tumorigenic potential in xenograft models. LRP8 knockdown also induces a more differentiated, luminal-epithelial phenotype and thus sensitizes the TNBC cells to chemotherapy. Together, our study highlights LRP8 as a novel therapeutic target for TNBC as inhibition of LRP8 can attenuate Wnt/ß-catenin signaling to suppress BCSCs.

Citizens' social media adoption in Paraguay / Adopción de redes sociales por parte de los ciudadanos en Paraguay / Adoção de redes sociais por cidadãos no Paraguai

Abstract This article aims to identify factors associated with the use of social media by Paraguayan citizens in their relationship with the government. We gathered data using a vignette survey, which recorded the responses to four public service problems and collected scores on perceived effectiveness, capability, social influence, trust in government, trust in social media infrastructure, and social media anxiety. Multivariate analysis was used to test the hypotheses. Perceived effectiveness, social influence, and trust in social media infrastructures were found to be significantly correlated with citizens' use of such media to report public service issues. On the other hand, capability, trust in government, and social media anxiety were not found to be associated with citizens' social media use. The results urge further theorization to disentangle how perceived effectiveness, social influence, and trust in social media infrastructures affect digital citizen engagement and participation and under what conditions proprietary social media platforms such as Facebook and Twitter contribute to a vibrant democracy.

Resumen Este artículo tiene como objetivo identificar qué factores están asociados con el uso de las redes sociales por parte de los ciudadanos paraguayos en las relaciones ciudadano-gobierno. Recopilamos datos mediante una encuesta basada en técnica de viñeta en la que se registraron las respuestas a cuatro problemas de servicio público, además de puntuaciones sobre la eficacia percibida, la capacidad, la influencia social, la confianza en el Gobierno, la confianza en la infraestructura de las redes sociales y la ansiedad con relación a las redes sociales. Se utilizó un análisis multivariado para probar las hipótesis. Se encontró que hay una correlación entre la efectividad percibida, la influencia social y la confianza en las infraestructuras de las redes sociales con el uso de las redes sociales por parte de los ciudadanos para informar sobre problemas de servicio público. Por otro lado, no se encontró que la capacidad, la confianza en el Gobierno y la ansiedad con relación a las redes sociales estuvieran asociadas con el uso de las redes sociales por parte de los ciudadanos. Los resultados nos instan a teorizar y desentrañar aún más cómo la efectividad percibida, la influencia social y la confianza en las infraestructuras propietarias de las redes sociales afectan el compromiso y la participación digital de los ciudadanos, y bajo qué condiciones las plataformas propietarias de las redes sociales propietarias ‒como Facebook y Twitter‒ contribuyen a una democracia vibrante.

Resumo Este artigo tem como objetivo identificar os fatores associados ao uso das redes sociais pelos cidadãos paraguaios nas relações cidadão-governo. A coleta dos dados foi feita usando uma pesquisa com vinhetas na qual as respostas a quatro problemas com serviços públicos foram registrados. Também foram coletadas pontuações sobre a percepção de eficácia, capacidade, influência social, confiança no governo, confiança na infraestrutura das redes sociais e ansiedade em relação às redes sociais. Uma análise multivariada foi usada para testar as hipóteses. A percepção de eficácia, a influência social e a confiança nas infraestruturas das redes sociais estão significativamente correlacionadas com o uso que os cidadãos fazem das redes sociais para relatar problemas nos serviços públicos. Por outro lado, a capacidade, a confiança no governo e a ansiedade em relação às redes sociais não foram associadas ao uso das redes sociais pelos cidadãos. Os resultados nos incentivam a formular mais teorias e desvendar como a percepção de eficácia, a influência social e a confiança nas infraestruturas das redes sociais afetam o envolvimento e a participação digital do cidadão, e em que condições as plataformas proprietárias de redes sociais, como o Facebook e o Twitter, contribuem para uma democracia vibrante.