FDA Draft Guidance Research Articles

Planning Split-Apheresis Designs for Demonstrating Comparability of Cellular and Gene Therapy Products.

A recent FDA draft guidance discusses statistical considerations for demonstrating comparability of cell and gene therapy products and processes. One experimental study described in the guidance is the split-apheresis design. The FDA draft guidance recommends a paired data analysis for such a design. This paper demonstrates that the paired analysis is under powered for some quality attributes for practical sample sizes of three to five donors unless a significant portion of variability is attributed to donor. Addition of historic lots from the pre-change process can increase the power for these attributes. This paper provides appropriate statistical methods for including this information.

Role of Clinical Pharmacology in Diversity and Inclusion in Global Drug Development: Current Practices and Industry Perspectives: WhitePaper.

The 2022 United States Food and Drug Administration (US FDA) draft guidance on diversity plan (DP), which will be implemented through the Diversity Action Plans by December 2025, under the 21st Century Cures Act, marks a pivotal effort by the FDA to ensure that registrational studies adequately reflect the target patient populations based on diversity in demographics and baseline characteristics. This white paper represents the culminated efforts of the International Consortium of Quality and Innovation (IQ) Diversity and Inclusion (D&I) Working Group (WG) to assess the implementation of the draft FDA guidance by members of the IQ consortium in the discipline of clinical pharmacology (CP). This article describes current practices in the industry and emphasizes the tools and techniques of quantitative pharmacology that can be applied to support the inclusion of a diverse population during global drug development, to support diversity and inclusion of underrepresented patient populations, in multiregional clinical trials (MRCTs). It outlines strategic and technical recommendations to integrate demographics, including age, sex/gender, race/ethnicity, and comorbidities, in multiregional phase III registrational studies, through the application of quantitative pharmacology. Finally, this article discusses the challenges faced during global drug development, which may otherwise limit the enrollment of a broader, potentially diverse population in registrational trials. Based on the outcomes of the IQ survey that provided the current awareness of diversity planning, it is envisioned that in the future, industry efforts in the inclusion of previously underrepresented populations during global drug development will culminate in drug labels that apply to the intended patient populations at the time of new drug application or biologics license application rather than through post-marketing requirements.

The practical impact of the FDA draft guidance on human mass balance studies – a year of client discussions

The practical impact of the FDA draft guidance on human mass balance studies – a year of client discussions

Abstract 3813: Relationship between race/ethnicity and oncologic outcomes in patients with biochemical recurrence after primary treatment for prostate cancer

Abstract Background: Prostate cancer (PC) is the most common form of cancer in men and accounts for ~35% and 24% of all new cancer diagnoses in Black and Hispanic men, respectively. Incidence rates of PC are higher and cancer is diagnosed at a younger age in Black compared to White men. The most frequently utilized primary treatment options are radical prostatectomy (with or without adjuvant radiotherapy) or radiotherapy. Despite the success of primary treatments for localized PC, many patients (pts) will eventually develop biochemical recurrence (BCR), defined as rising prostate-specific antigen (PSA) levels. Pts with BCR are at a higher risk of developing distant metastases and ultimately dying from PC. This targeted literature review aimed to assess the real-world (RW) relationship between race/ethnicity and BCR, and further identify any differences in oncologic outcomes (risk of metastases, PC-specific mortality, and overall survival). Methods: A targeted literature search was performed using Embase, PubMed, and the past 2 years of American Society of Clinical Oncology conference proceedings. Selected studies were limited to English-language articles focusing on BCR and race or ethnicity among US populations, published between 1/2010 and 7/2023. Results: Ten studies were selected after title and abstract review. Most studies had a White pt majority (83%-92%). Six studies reported no differences in BCR or oncologic outcomes when pts were stratified by race/ethnicity. Four studies reported a higher BCR risk for Black pts with low-risk PC after radical prostatectomy, but not for pts with high-risk PC. PSA and PSA doubling time (PSADT) were found to be strong predictors of oncologic outcomes. Conclusions: The FDA draft guidance on diversity plans recommends that clinical trials enroll an adequate number of participants from underrepresented racial and ethnic populations. This requires an understanding of the diversity of the population that will eventually use the treatment and of which race/ethnicity differences in outcomes should be expected and investigated. Based on this targeted review among pts with localized PC, most RW studies had a White pt majority, and the race distribution in these studies aligned with published census and epidemiology data. In addition, findings suggest that race/ethnicity differences were not pronounced among high-risk PC pts in the US when given equal access to care or treatment, and that oncologic outcomes and BCR risk were similar across Black, White, and Hispanic pt populations. Conversely, PSA and PSADT may be stronger prognostic markers for BCR and oncologic outcomes. Future clinical trials are needed to support these RW findings and should aim to actively enroll racial/ethnic minorities to identify potential differences in efficacy and safety, and to help advance the evidence base for pt PC management. Citation Format: Nasreen Khan, Vanessa Quintero, Clara Beck, Miryana Dimova-Dobreva, Binita Patel. Relationship between race/ethnicity and oncologic outcomes in patients with biochemical recurrence after primary treatment for prostate cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 3813.

A Tumor-Bearing Murine Xenograft Model As a Bioassay for Assessing CAR-T Product Potency Shows Positive Predictive Value for Clinical Performance

Potency assays are required for cellular and gene therapy (CGT) final product (FP) lot release, stability testing, and manufacturing updates, as per the FDA draft guidance on Potency Tests for CGT Products (2011), and Manufacturing Changes and Comparability for Human CGT Products (2023). These assays by definition measure the ability of a product to effect a desired result, and the FDA allows for “considerable flexibility” in determining the appropriate potency assay. However, standard in vitro potency assays are limited in their capacity to meaningfully assess manufacturing comparability and consistency, or product quality to provide predictive value for clinical performance. For chimeric antigen receptor (CAR)-T cell products, certificates of analysis typically report key FP attributes such as CAR expression, cell concentration and viability, impurities and target-specific in vitro potency, among others. However, clinical effectiveness of CAR-T is dependent on complex pharmacokinetics (PK)/ pharmacodynamics (PD) including in vivo engraftment, trafficking, drug exposure kinetics, tumor antigen-driven T cell expansion in tumor microenvironment, survival and persistence, and other factors that are not easily recapitulated in short-term in vitro assays. We developed a bioassay for assessing CAR-T FP potency using a tumor-bearing murine NSG xenograft model to evaluate in vivo performance of GMP-manufactured autologous (Auto) or allogeneic (Allo) CAR-T FPs. We hypothesized that this complex in vivo system may better model PK/PD and provide a more meaningful way to assess CAR-T FP potency. Preclinical dose-finding data from both RUO and GMP anti-BCMA CAR-T lots were used to establish a potency specification for RPMI-8226 tumor control at a “stress dose” of 5e6 CAR-T cells at <60% of the tumor volume compared to the untreated control group at 21 days after CAR-T cell infusion. Using these specifications, we evaluated the in vivo potency performance of GMP-manufactured Auto FP samples (P-BCMA-101; NCT03288493) generated from multiple myeloma (MM) patients and administered in the clinic with known responses ranging from poor (no response or stable disease) to significant (very good partial response [VGPR] or stringent complete response [sCR]). In addition, GMP-manufactured Allo FP samples generated from healthy donors (P-BMCA-ALLO1; NCT04960579) were also tested. We report that half of the P-BCMA-101 products (50%) previously demonstrating favorable clinical outcomes in MM patients were also able to control RPMI-8226 tumor in vivo, while none of the P-BCMA-101 products (0%) that resulted in poor clinical responses were capable of tumor control. These data show translational relevance considering the known clinical outcomes in MM patients, albeit at a high level of stringency at current specifications. Interestingly, all the Allo products (100%) performed at least as well as or better than the Auto products capable of controlling tumor, demonstrating a greater potency of Allo CAR-T cells manufactured from healthy donors. There is great demand for potency assays that can reliably assess manufacturing consistency and product quality, and that might provide some level of predictive value for clinical performance, especially considering the current limitations of standard in vitro potency assays. In vivo potency bioassays have been proposed or utilized for other products with complex biological mechanisms of action including vaccines, gene therapies, and other cell therapy products. The potency bioassay described herein demonstrated a level of positive predictive value for clinical performance using Auto FPs of known clinical outcome in MM patients. In the Auto CAR-T setting, this assay could be utilized for correlative studies including possible biomarker identification. In the Allo CAR-T setting, this potency bioassay may inform FP manufacturing consistency and quality for lot release to ensure patients receive only the highest quality products.

A comprehensively validated IVRT method reliably discriminates sameness and differences between several topical clotrimazole creams

In vitro release testing (IVRT) has gained increasing acceptance for use as a biowaiver for topical products intended for local action. Whereas the United States Food and Drug Administration (US FDA) has issued product specific guidances (PSGs) recommending IVRT for several products, the PSG for clotrimazole cream does not include an IVRT option. However, an important requirement to include supplemental selectivity in the validation process as described in the recent FDA draft guidance on IVRT studies for topical drug products has generally been conspicuously absent in the published literature describing the application of IVRT as a biowaiver. Supplemental selectivity involves the comparison of a reference product and altered formulations containing the same strength of the active pharmaceutical ingredient (API). In order to demonstrate supplemental selectivity, cream formulation containing the same API (clotrimazole), at the same strength (1 %) and in the same dosage form (cream) but manufactured using different excipients were used. This will help assess the impact that excipients may have on the release rate of clotrimazole and whether the method is capable of identifying differences in the microstructure and arrangement of matter (Q3) as an important performance parameter. In addition, products containing <30 % or >40 % clotrimazole to serve as negative controls were also included for the discriminatory power assessment. Hence, the primary objective was to develop and validate a simple, reliable, reproducible, and cost-effective in vitro technique in accordance with the recent draft FDA guidance to assess the “sameness” of topical creams containing 1 % clotrimazole. An in vitro release testing (IVRT) system was used and an IVRT method was developed and accordingly validated. The validated IVRT method showed the potential to accurately measure the release from 1 % clotrimazole creams and demonstrated supplemental selectivity and appropriate discriminatory power to identify "sameness" and/ or differences.

Adaptive designs for IVPT data with mixed scaled average bioequivalence.

In vitro permeation tests (IVPT) offer accurate and cost-effective development pathways for locally acting drugs, such as topical dermatological products. For assessment of bioequivalence, the FDA draft guidance on generic acyclovir 5% cream introduces a new experimental design, namely the single-dose, multiple-replicate per treatment group design, as IVPT pivotal study design. We examine the statistical properties of its hypothesis testing method-namely the mixed scaled average bioequivalence (MSABE). Meanwhile, some adaptive design features in clinical trials can help researchers make a decision earlier with fewer subjects or boost power, saving resources, while controlling the impact on family-wise error rate. Therefore, we incorporate MSABE in an adaptive design combining the group sequential design and sample size re-estimation. Simulation studies are conducted to study the passing rates of the proposed methods-both within and outside the average bioequivalence limits. We further consider modifications to the adaptive designs applied for IVPT BE trials, such as Bonferroni's adjustment and conditional power function. Finally, a case study with real data demonstrates the advantages of such adaptive methods.

2022 White Paper on Recent Issues in Bioanalysis: FDA Draft Guidance on Immunogenicity Information in Prescription Drug Labeling, LNP & Viral Vectors Therapeutics/Vaccines Immunogenicity, Prolongation Effect, ADA Affinity, Risk-based Approaches, NGS, qPCR, ddPCR Assays (Part 3 - Recommendations on Gene Therapy, Cell Therapy, Vaccines Immunogenicity & Technologies; Immunogenicity & Risk Assessment of Biotherapeutics and Novel Modalities; NAb Assays Integrated Approach).

The 2022 16th Workshop on Recent Issues in Bioanalysis (WRIB) took place in Atlanta, GA, USA on September 26-30, 2022. Over 1000 professionals representing pharma/biotech companies, CROs, and multiple regulatory agencies convened to actively discuss the most current topics of interest in bioanalysis. The 16th WRIB included 3 Main Workshops and 7 Specialized Workshops that together spanned 1week in order to allow exhaustive and thorough coverage of all major issues in bioanalysis, biomarkers, immunogenicity, gene therapy, cell therapy and vaccines. Moreover, in-depth workshops on ICH M10 BMV final guideline (focused on this guideline training, interpretation, adoption and transition); mass spectrometry innovation (focused on novel technologies, novel modalities, and novel challenges); and flow cytometry bioanalysis (rising of the 3rd most common/important technology in bioanalytical labs) were the special features of the 16th edition. As in previous years, WRIB continued to gather a wide diversity of international, industry opinion leaders and regulatory authority experts working on both small and large molecules as well as gene, cell therapies and vaccines to facilitate sharing and discussions focused on improving quality, increasing regulatory compliance, and achieving scientific excellence on bioanalytical issues. This 2022 White Paper encompasses recommendations emerging from the extensive discussions held during the workshop and is aimed to provide the bioanalytical community with key information and practical solutions on topics and issues addressed, in an effort to enable advances in scientific excellence, improved quality and better regulatory compliance. Due to its length, the 2022 edition of this comprehensive White Paper has been divided into three parts for editorial reasons. This publication (Part 3) covers the recommendations on Gene Therapy, Cell therapy, Vaccines and Biotherapeutics Immunogenicity. Part 1 (Mass Spectrometry and ICH M10) and Part 2 (LBA, Biomarkers/CDx and Cytometry) are published in volume 15 of Bioanalysis, issues 16 and 15 (2023), respectively.

Completion rates and trends of the patient-reported outcomes version of the Common Terminology Criteria for Adverse Events (PRO-CTCAE) across 14 oncology clinical trials.

1579 Background: With growing emphasis on patient-centered regulatory decision making, there is a greater need to incorporate the patient’s voice in oncology clinical trials. Regulatory guidelines outline core patient-reported outcomes (PROs) to include which can inform risk/benefit evaluation. Self-reported symptomatic adverse events (AE) form part of these core PROs, with the new 2023 draft FDA guidance acknowledging the benefits of including them to enhance the assessment of tolerability in early phase dose optimization trials. Given the clinical symptoms and disease burden in oncology, patient burden needs to be thoughtfully considered when incorporating PROs into trials. We assessed trends and feasibility of electronic data collection for symptomatic AEs by analyzing completion compliance and time to complete the Patient-Reported Outcomes version of the Common Terminology Criteria for Adverse Events (PRO-CTCAE) across 14 oncology trials. Methods: All PRO-CTCAE were collected electronically on Clario Tablets. Operational data for completion status (completed or missed) and duration of time to complete the PRO-CTCAE in seconds was extracted. Completion rates over time were examined overall and for every 3-month interval (quarters Q1 to Q9+). The median was selected for analyses of time to complete to account for skewness. Results: The sample included 14 studies across Phase I-III trials across a range of cancers including multiple myeloma, mesothelioma and cancers of the lung, prostate, head/neck, gastric, breast, and ovary. Study durations were 24 weeks and up. The PRO-CTCAE form was completed 13,122 times and missed in 1,182 instances, giving an overall completion rate of 91.7%. On average, 25 questions (range 5-47) covered an average of 13 symptoms (range: 4-25). Completion rate was not associated with the number of questions asked or time since enrollment. The overall median time to complete the PRO-CTCAE was 82s (study-specific median range: 24s to 276s). Examining time to completion as a function of the number of questions revealed a significant positive association, such that each additional question added 5.2 seconds to the time it took to complete the assessment. Conclusions: Completion compliance was high for PRO-CTCAE and remained high regardless of study length and the number of questions included in the PRO-CTCAE form. This suggests that electronic PRO-CTCAE is a feasible solution for collecting self-reported symptomatic AEs. Although time to complete the form increased with the number of questions, results suggest that including a higher number of PRO-CTCAE questions does not negatively impact compliance rate. Our data showing high completion rates may also reflect the benefits of electronic PROs in reducing patient burden and enhancing data quality, as acknowledged by regulatory agencies.

D70. Suspicious or Safe? A Systematic Review on the Impact of FDA Guidance on Reporting of Fat Necrosis in Autologous Fat Grafting of the Breast

PURPOSE: Autologous fat grafting (AFG), increasingly popular in breast reconstruction and augmentation, often causes fat necrosis. In late-2014, the FDA draft guidance recommended cessation of all AFG. In late-2017, the final guidance was updated to allow AFG with restrictions. The landscape of clinically relevant fat necrosis reporting remains undescribed in the context of these changing guidelines. METHODS: PubMed, Embase, Cochrane, Web of Science, and Scopus were queried for studies mentioning fat necrosis and fat grafting in breast reconstruction or augmentation from inception to August 11, 2022. Of the 1359 articles identified, 62 met inclusion criteria. Studies were temporally stratified according to released FDA guidelines. RESULTS: 7 of 22 (31.8%) studies pre-2014 FDA draft guidance used clear fat necrosis definitions. There is an absence of defining fat necrosis in the 13 studies between 2015 and the late-2017 FDA guidance (p=0.023). After the 2017 guidance, only 3 of 27 (11.1%) studies clearly followed FDA recommendations to define fat necrosis. Among the 10 studies defining fat necrosis, none used identical definitions. 52 (83.9%) of all studies did not define what constituted fat necrosis. CONCLUSION: Clear fat necrosis definitions are not consistently utilized in literature describing autologous fat transfer of the breast, despite FDA recommendations. Given the rise of non-PRS-performed fat grafting procedures, we call on the PRS community to commit to uniformly reporting clinically distinct fat necrosis complications.

CSA: Much Ado About Nothing?

Computerized system validation (CSV) in good practice (GxP)-regulated laboratories is alleged to take ages and generate piles of paper to keep inspectors and auditors quiet. To the rescue is the draft FDA guidance on computer software assurance (CSA). But...is this really the case?

Breast Implant Illness: Identifying Patients Concerns from Public Comments on Regulation.gov

INTRODUCTION: Breast Implant Illness is an evolving syndrome that has been gaining traction from the public and the medical community. Patients are experiencing negative emotions towards BII and are dissatisfied with the quality of patient education, as expressed in the public comments submitted in response to the 24OCT2019 FDA draft guidance on breast implant labeling recommendations. To better gauge the patient experience, this study aims to further examine these comments for frequently encountered concerns and themes. METHODS: The comments under the 24OCT2019 Regulations.gov docket were extracted. A team of 14 researchers examined them to detect recurring themes. The comments were then equally and randomly allocated to two independent reviewers to code for the presence of the identified themes, and to a third reviewer for conflict reconciliation. Microsoft Excel was used to quantify theme frequencies. RESULTS: The docket contained 1321 comments, of which 4 were not in English, 10 were duplicates and 449 represented repetitions of a template expressing dissatisfaction with the guidelines. Amongst the remaining 758 comments, we identified the following recurrent concerns and themes: 1) insufficiency of FDA guidelines (present in 37% of the 758 comments), 2) feelings of betrayal by doctors, implant manufacturers and/or insurance companies (29.7%), 3) requesting a complete list of ingredients and metals (18.6%), 4) requesting a patient checklist (15%), 5) surgeons, other physicians, or nurses not being able to explain the patient’s symptoms (13.5%), 6) requesting all breast implants to be banned (10.4%), 7) doctors not acknowledging patients’ BII concerns (8.6%), 8) concern about gel bleed/migration (6.2%), 9) explant not covered by insurance (5.7%), 10) patients recognizing they have BII only after coming across a social media group discussing it, or a friend who has it or read about it (4.2%), 11) requesting advocacy for recognition of BII by insurance companies (3.1%), 12) requesting only silicone breast implants to be banned (2.9%), 13) mention/discussion of the previous silicone implant ban (2.1%). CONCLUSION: Patients are expressing several concerns about the safety of breast implants, the FDA guidelines, breast implant illness, and patient education. Notably, the trust towards the medical community is being questioned as patients feel betrayed and dismissed. Breast implants represent one of the mainstay treatments for post-mastectomy breast reconstruction, and their condemnation may compromise the quality of patient outcomes. Therefore, further research is needed to characterize breast implant illness and improve patient advocacy. Interestingly, the FDA updated their labeling recommendation for improved patient communication to include a patient decision checklist which is also reflected by our findings (15% of comments). Our results can serve as a springboard to proactively address patients concerns for optimized patient-physician relationship and restore the trust that qualified plastic surgeons will always have the patients best-interest in mind.

OP12 Considerations for New Product Planning in Light of FDA Draft Guidance on Benefit-Risk Assessment

FDA regulatory evidence requirements currently focus on a product’s pharmacology, efficacy, and safety. In 2021, FDA released draft guidance on benefit-risk assessment for new drug and biological products. This emerging guidance suggests an evolution towards more holistic approaches to drug evaluation, incorporating evidence on disease burden and unmet need, particularly from patient/caregiver perspectives, alongside product efficacy and safety.

The Pandemic Supercharged Decentralized Trials, Now What?

The Pandemic Supercharged Decentralized Trials, Now What?

Vehicles for Drug Administration to Children: Results and Learnings from an In-Depth Screening of FDA-Recommended Liquids and Soft Foods for Product Quality Assessment

PurposeMixing with liquids or soft foods is a common procedure to improve acceptability of oral medicines in children but may affect drug stability and the in vivo performance of the administered drug product. The aim of the present study was to obtain an overview of the variability of critical attributes of commonly used vehicles and to identify which vehicle characteristics need to be considered when developing in vitro methods for evaluating product quality.MethodsOne product of each vehicle listed in the FDA draft guidance “Use of Liquids and/or Soft Foods as Vehicles for Drug Administration” was analyzed with regard to composition, calorific content and physicochemical properties.ResultsThe studied vehicles show wide variability, both in composition and physicochemical properties. No correlation was observed between vehicle composition and physicochemical properties. Comparison of results of the present study with previously published data also provided variability in physicochemical properties within individual vehicle types.ConclusionsTo identify acceptable (qualified) vehicles for global drug product labeling, it is important that the vehicles selected for in vitro compatibility screening reflect the variability in composition and essential physicochemical properties of the vehicles recommended on the product label, rather than relying on results obtained with a single vehicle of each type. Future activities will focus on the development of standardized dosing vehicles that can represent key vehicle characteristics in all their variability to ensure reliable risk assessment.

Disease progression models of familial frontotemporal lobar degeneration and the temporal ordering of biomarker changes in an international cohort

AbstractBackgroundClinical trials are underway to treat familial frontotemporal lobar degeneration (f‐FTLD). This is a rare disease, and a limited number of mutation carriers have been identified; thus, efficient trial design is critical. Multimodal, latent disease progression models (DPM) can estimate time to symptom onset and define the temporal ordering of biomarker changes. DPMs can also be leveraged to select endpoints and potentially supplement analyses by integrating historical data. Recent draft FDA guidance for gene therapy trials in neurological disease supports these novel approaches to clinical trials.MethodParticipants included 1,049 members of families affected by f‐FTLD, due to mutations in GRN, MAPT, or C9orf72 genes, who were enrolled in ALLFTD or GENFI. A Bayesian repeated measures model incorporated multimodal data to estimate disease progression, conditional on latent disease age (proximity to symptom onset), in 677 mutations carriers (GRN (n=233), MAPT (n=151) and C9orf72 (n=293)). Family members without pathogenic mutations were used as the reference group. Mean follow‐up was 1.1 (SD=1.1) years. Jointly modeled longitudinal variables included neuropsychological scores, CDR®+NACC‐FTLD Box Score, MRI volumes of brain regions affected by f‐FTLD, and plasma levels of neurofilament light chain (NfL).ResultDisease progression curves were similar across ALLFTD and GENFI cohorts. Plasma NfL elevations occurred earliest, up to 10 years before symptom onset, and NfL was the most powerful endpoint in the asymptomatic stage. MRI abnormalities occurred next, closer to symptom onset. The earliest MRI changes relative to symptom onset were observed in C9orf72+. GRN mutation carriers showed the most rapid acceleration in all biomarkers, and this acceleration occurred in close proximity to symptom onset. Neuropsychological measures and CDR®+NACC‐FTLD Box Score were among the most promising endpoints in the symptomatic stage. Trial simulations indicated that using latent disease age as an enrollment criterion would allow some asymptomatic mutation carriers to be enrolled without sacrificing power.ConclusionSimilarity in disease progression across ALLFTD and GENFI participants suggests these models will apply to international trials. Model‐derived estimates of disease progression curves indicate that endpoint selection should be specific to disease stage and mutation, and DPMs would facilitate greater participant enrollment.

FDA draft guidance on benefit-risk assessments for NDAs and BLAs

FDA draft guidance on benefit-risk assessments for NDAs and BLAs

Pre-incubation with OATP1B1 and OATP1B3 inhibitors potentiates inhibitory effects in physiologically relevant sandwich-cultured primary human hepatocytes

Organic anion transporting polypeptides (OATP)1B1 and OATP1B3 are liver-specific transport proteins that express on the basolateral membrane of human hepatocytes and mediate hepatic uptake of many drugs, including statins. They are important determinants of transporter-mediated drug-drug interactions (DDIs). It has been reported that pre-incubation with some OATP1B1 and OATP1B3 inhibitors potentiates the inhibitory effects, yielding reduced IC50 values. The US FDA draft guidance has recently recommended to use the lower IC50 values after inhibitor-preincubation to assess OATP1B1 and OATP1B3-mediated DDIs. However, it remains unknown whether the potentiation effects of inhibitor-preincubation on IC50 values occur in a physiologically relevant cell model. The current study was designed to determine the IC50 values of OATP1B1 and OATP1B3 inhibitors everolimus (EVR), sirolimus (SIR), and dasatinib against OATP1B substrates in physiologically relevant primary human hepatocytes with or without inhibitor-preincubation and to compare the OATP-mediated DDI prediction using data from primary human hepatocytes and that reported previously in transporter-expressing cell lines. Primary human hepatocytes were cultured in a sandwich configuration. Accumulation of [3H]-CCK-8 (1 µM, 1.5 min), [3H]-rosuvastatin (0.5 µM, 2 min) and [3H]-pitavastatin (1 µM, 0.5 min) was determined in human sandwich-cultured hepatocytes (SCH) in the presence of vehicle control or an inhibitor with or without inhibitor-preincubation at designated concentrations, and was utilized to determine the IC50 values for these inhibitors. R-value models were used to predict OATP-mediated DDIs. Pre-incubation with EVR at a clinically relevant concentration of 0.2 µM significantly reduced accumulation of [3H]-CCK-8 and [3H]-rosuvastatin even after washing. Reduced IC50 values following inhibitor pre-incubation were observed for all three inhibitors using [3H]-CCK-8 and [3H]-rosuvastatin as substrates in human SCH. The IC50 values after inhibitor-preincubation were lower or comparable in transporter-expressing cell lines compared with that in human SCH. For dasatinib, R-values from both cell lines and human SCH were greater than the US FDA cut-off value of 1.1. For EVR, R values from cell lines were 1.23 and were lowered to near 1.1 (1.08–1.09) in human SCH. For SIR, R values from either cell type were less than the cut-off values of 1.1. In conclusion, the current study is the first to report that pre-incubation with OATP1B inhibitors potentiates inhibitory effects in physiologically relevant primary human hepatocytes, supporting the rationale of the current US FDA draft guidance of including an inhibitor-preincubation step when assessing OATP-mediated DDIs in vitro. IC50 values after inhibitor-preincubation in transporter-expressing cell lines may be used for DDI prediction for the purpose of mitigating false-negative OATP-mediated DDI prediction.

Potassium chloride-based replacers: modeling effects on sodium and potassium intakes of the US population with cross-sectional data from NHANES 2015–2016 and 2009–2010

ABSTRACTBackgroundSodium intake in the USA exceeds recommendations. The replacement of added sodium chloride (NaCl) with potassium chloride (KCl) provides a potential strategy to reduce sodium intake.ObjectiveThe purpose of this study was to quantitatively estimate changes in intakes of sodium and potassium by the US population assuming use of potassium-based NaCl replacers in top dietary sodium sources.MethodsData collected in the What We Eat in America (WWEIA) component of the 2015–2016 and 2009–2010 NHANES were used to identify top-ranking sources of dietary sodium among the population aged 2 y and older based on contributions from food categories aligning with the FDA draft guidance for voluntary sodium reduction. Predicted nutrient intakes were estimated in models assuming total and feasible and practical (F&P) replacement of added NaCl with KCl in foods and ingredients within the top food sources of sodium. An expert elicitation was conducted to collect information on the F&P KCl replacement of added NaCl.ResultsUsing 2015–2016 consumption data, the total replacement of added NaCl with KCl in the 18 top-ranking sources of dietary sodium results in a predicted sodium intake of 2004 mg/d from the replacement of 1406 mg/d sodium with 1870 mg/d potassium as KCl. Modeled F&P replacement predicted sodium intakes of 3117 mg/d (range of 2953 to 3255 mg/d) from the replacement of 294 mg/d sodium (155 to 457 mg/d) with 390 mg/d potassium (206 to 608 mg/d). Similar results are seen with 2009–2010 data.ConclusionsThe F&P replacement of NaCl with KCl in top-ranking sources of dietary sodium modeled in this study can result in decreased sodium to a level consistent with the short-term intake goal targeted by the FDA of 3000 mg/d, with the mean potassium intake remaining in the range recommended for the apparently healthy population.

The 21-day cumulative irritation assay in man: a half-century summary and re-evaluation

The 21-day cumulative irritation test (21-day CIT) has been widely used in dermatopharmacology and dermatotoxicology to assess the irritation potential of topical products. Since described by Lanman in 1968, it has been modified, shortened, re-evaluated, and statistically analysed by multiple groups of authors. As the assay has been recommended in FDA draft guidance, we bring subsequent experience to date. The shorter 14-day version is commonly used and may be as adequate as the 21-day application when used to discriminate between moderate to strong irritants. While previous authors stopped the test when subjects experienced an irritation score of 3 or more, the FDA suggested moving the test to another anatomical site to complete in 21 days. This approach avoids assumptions, thus may be more accurate to quantify skin irritation. As the scoring is based on visual grading, the 21-day CIT also does not account for sensory irritation. Therefore, future studies need to propose a way to evaluate the sensation objectively in dermatological product development.