The AAPS Journal[JOURNAL]
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200 papers
Proceedings of the 2024 FDA-CRCG Workshop: Scientific and Regulatory Considerations for Assessment of Immunogenicity Risk for Generic Peptide and Oligonucleotide Drug Products.
Lee JK, Lee HN, Agrawal S … +42 more , Balsamo JA, Clerman A, Denies S, De Groot A, Fry J, Gaudenzio N, Graves AJ, Howard KE, Hwang S, Jawa V, Jin Y, Kelly-Baker L, Knowlton E, Kolenc F, Sivakumar KK, Lee JH, Li Y, Liang L, Liu D, Liu Y, Lionberger R, Luke MC, Manangeeswaran M, Mendoza M, Murphy I, Norcross M, Polli JE, Puig M, Rao Sp N, Rogers H, Schwendeman A, Siegel R, Shubow S, Smith N, Thacker SG, Tourdot S, Yang K, Zhang L, Zhang D, Smith CJ, Pang ES, Verthelyi D
AAPS J · 2026 Feb · PMID 41680369 · Publisher ↗
On Oct 7 and 8, 2024, the US Food and Drug Administration (FDA) and the Center for Research on Complex Generics (CRCG) co-hosted a workshop titled "Scientific and Regulatory Considerations for Assessment of Immunogenicit...
On Oct 7 and 8, 2024, the US Food and Drug Administration (FDA) and the Center for Research on Complex Generics (CRCG) co-hosted a workshop titled "Scientific and Regulatory Considerations for Assessment of Immunogenicity Risk for Generic Peptide and Oligonucleotide Drug Products". Stakeholders from the FDA, industry, academia, and contract research organizations convened to discuss strategies for advancing risk assessment methodologies and regulatory frameworks for complex generic products. By assembling experts from various sectors, the workshop explored various available strategies for immunogenicity risk assessment, providing valuable insights to support the development and assessment of generic peptide and oligonucleotide drug products. The discussions fostered a deeper understanding of how these methodologies can inform regulatory decision-making and enhance the development of safer and more effective therapeutics.
Antimicrobial Resistance: Italian and American Efforts to Counter it.
Vitiello A, Ponzo A, Boccellino M … +1 more , Zovi A
AAPS J · 2026 Feb · PMID 41667907 · Publisher ↗
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Utility of Modeling and Simulations in Drug Development: Contrasting Japan, US and UK Descriptions of PBPK Modeling from Package Inserts.
Kudo S, Wakuda H, Oikawa I … +6 more , Sekiguchi A, Nakamura Y, Hojo T, Imai H, Kai M, Uemura N
AAPS J · 2026 Feb · PMID 41667884 · Publisher ↗
Physiologically based pharmacokinetic (PBPK) modeling is a mathematical method for predicting drug pharmacokinetics based on individual physiological information, and its usefulness has been attracting attention in recen...
Physiologically based pharmacokinetic (PBPK) modeling is a mathematical method for predicting drug pharmacokinetics based on individual physiological information, and its usefulness has been attracting attention in recent years. This study aimed to investigate and compare the extent to which PBPK models are utilized in drug package inserts in Japan, the United States, and Europe. We searched the official websites of the PMDA, FDA, and EMA to examine the number and content of drugs that mention the use of PBPK modeling as of 2024. Furthermore, we compared the consistency and detail of the descriptions between Japan, the United States, and Europe. As a result, 38 drugs in Japan listed PBPK modeling, many of which were related to drug-drug interactions. Compared with Europe, there were no complete matches and only seven partial matches, while compared with the United States, there were two complete matches and 24 partial matches. A comparison of the details of the 24 partial matches revealed a tendency for Japanese package inserts to be more detailed. PBPK model analysis has become increasingly important in recent drug development, and Japan in particular has a tendency to provide more detailed information on package inserts. This study suggests the potential for further utilization of PBPK models in the field of clinical pharmacology.
Perspectives on PCR-Based Cellular Kinetics and Biodistribution Analysis for Emerging Adoptive Cell Therapies.
Balasubramanian N, Gudey SK, Lu Y … +2 more , Rocha AG, Sugimoto H
AAPS J · 2026 Feb · PMID 41667750 · Publisher ↗
A growing number of chimeric antigen receptor (CAR) T-cell therapies have been developed and investigated in clinical studies, with several FDA-approved therapies targeting CD19 and BCMA antigens on hematological maligna...
A growing number of chimeric antigen receptor (CAR) T-cell therapies have been developed and investigated in clinical studies, with several FDA-approved therapies targeting CD19 and BCMA antigens on hematological malignancies. To further expand the indication to solid tumors and autoimmune diseases, a new generation of CAR T-cell therapies has been investigated to explore new tumor-associated antigens, allogeneic options, and cytokine armoring strategies, etc. to overcome the current limitations, including safety concerns, relapse rates, tumor microenvironment challenges, patient accessibility and manufacturing complexities. Cellular kinetics and biodistribution assessments are crucial in understanding the efficacy and safety of cell therapy, as a living drug that typically exhibits four distinct phases: distribution, expansion, contraction, and persistence within the body. Droplet digital PCR has emerged as the technology of choice in cell and gene therapy for transgene quantification with higher sensitivity, specificity, reproducibility, and absolute quantification, and as an end-point PCR provides higher tolerance to PCR inhibition. In the meantime, several unique challenges remain to be addressed in the cellular kinetics and biodistribution studies of CAR T, depending on the program stage, types of immune cells, and target indication (hematological and solid tumors, autoimmune). This opinion paper discusses the challenges and considerations of PCR-based cellular kinetics and biodistribution assessment to support emerging adoptive cell therapy programs.
A Data-driven Stepwise Approach to Cross Validation of Clinical Anti-Drug Antibody (ADA) Assays.
Ye S, Mao Y, Coble K
AAPS J · 2026 Feb · PMID 41667701 · Publisher ↗
Cross-validating bioanalytical assays between laboratories is challenging, and antidrug antibody (ADA) assays are particularly difficult to cross-validate due to the lack of regulatory guidance specific to this topic. As...
Cross-validating bioanalytical assays between laboratories is challenging, and antidrug antibody (ADA) assays are particularly difficult to cross-validate due to the lack of regulatory guidance specific to this topic. As a result, different companies have adopted varying approaches. Currently, bioanalytical practices for ADA assay cross-validation are not harmonized. Therefore, it is important to share individual company experiences and practices to facilitate harmonization for industry standards. This manuscript presents Boehringer Ingelheim's strategy and practice, referred to as a "data-driven stepwise approach," for clinical ADA assay cross-validation. In Step 1, the ADA assay is first validated at the reference laboratory and then qualified at the comparator laboratory. In Step 2, both laboratories demonstrate comparable responses through cut-point evaluation, confirmed by statistical analysis. In Step 3, identical blinded test samples are analyzed at both laboratories to confirm consistent classification of results as ADA-negative or ADA-positive. Upon satisfactory completion of these steps, the ADA assay is considered successfully cross-validated from the reference laboratory to the comparator laboratory. Case studies are also presented.
Industry Practices in Oligonucleotide Tissue Biodistribution Assessment: An IQ consortium Cross-Industry Survey of Current Approaches and Emerging Trends.
McCoy M, Tang H, Michaut L … +6 more , Laczkovich I, Chopda G, Chen L, Taneja I, Boswell CA, Zhang G
AAPS J · 2026 Jan · PMID 41612090 · Publisher ↗
Accurate assessment of tissue distribution for oligonucleotide therapeutic (ONT) drug candidates is essential for understanding pharmacokinetic behavior and predicting therapeutic efficacy. ONTs present a unique challeng...
Accurate assessment of tissue distribution for oligonucleotide therapeutic (ONT) drug candidates is essential for understanding pharmacokinetic behavior and predicting therapeutic efficacy. ONTs present a unique challenge with their rapid systemic clearance coupled with prolonged tissue retention, making comprehensive tissue concentration evaluation critical for successful drug development. The IQ Consortium Tissue Concentration Working Group surveyed member companies about their current tissue concentration assessment methods to understand industry practices and identify areas for improvement. Most companies reported that ONTs still represent a relatively small portion of their pre-candidate selection portfolios, reflecting the evolving nature of this therapeutic modality. siRNAs dominated development efforts across surveyed organizations, followed by antisense oligonucleotides, indicating clear therapeutic class preferences within the industry. Assessment strategies varied considerably across organizations, highlighting different approaches to resource allocation and risk management. While some companies routinely evaluate tissue concentrations for all ONT programs regardless of indication or target, others take a more selective, program-dependent approach based on compound characteristics and therapeutic objectives. Despite this strategic variability, there was universal reliance on LC-MS for quantification, often supplemented with qPCR/RT-qPCR and hybridization assays for comprehensive analytical coverage. All surveyed companies integrate tissue concentration data into translational pharmacokinetic modeling efforts, yet few have adopted physiologically-based pharmacokinetic (PBPK) models as standard practice. Companies recognize the value of improving ONT tissue distribution assessment through standardized methodology tailored to specific oligonucleotide classes.
Identification of HLA Variants Associated with Symptomatic and Asymptomatic COVID-19 Using a Machine Learning Approach.
Rawal A, Sauna Z
AAPS J · 2026 Jan · PMID 41588244 · Publisher ↗
COVID-19 disease outcomes can vary considerably among infected patients. Most studies have focused on patients with severe COVID-19. However, investigations of asymptomatic infection can provide insights into patient-spe...
COVID-19 disease outcomes can vary considerably among infected patients. Most studies have focused on patients with severe COVID-19. However, investigations of asymptomatic infection can provide insights into patient-specific immunological features that protect patients from COVID-19 symptoms. Recent studies have shown an association between common human leukocyte antigen (HLA) alleles and asymptomatic COVID-19 infections. Here we utilize machine learning in conjunction with explainable AI (XAI) to identify alleles in five HLA loci that can be either protective or put the patient at risk for symptomatic COVID-19. Data from the public online HLA-COVID database (1946 samples) was used for training and validating multiple ML classification models to identify the top performing model. The model was then further processed with XAI via SHAP (SHapley Additive exPlanations) to identify the protective and high-risk HLA alleles. This study provides a proof-of-concept study for utilizing machine learning to provide valuable insights for COVID-19 patients. These findings can be translated into clinical algorithms to help physicians personalize COVID-19 treatments and achieve better clinical outcomes.
Pharmacokinetics of Inhibitors of Succinyl-CoA:3-Ketoacid CoA Transferase in Sprague-Dawley Rats, and the Effect of a High-Fat Diet.
Al Nebaihi HM, Dakhili SAT, Ussher JR … +1 more , Brocks DR
AAPS J · 2026 Jan · PMID 41578070 · Publisher ↗
Pimozide and PSSI-51 are under study for their potential glucose-lowering effects in type 2 diabetes, through their abilities to inhibit succinyl-CoA:3-ketoacid CoA transferase, the rate-limiting enzyme of ketone oxidati...
Pimozide and PSSI-51 are under study for their potential glucose-lowering effects in type 2 diabetes, through their abilities to inhibit succinyl-CoA:3-ketoacid CoA transferase, the rate-limiting enzyme of ketone oxidation. To understand their pharmacokinetics, they were administered to Sprague Dawley male and female rats after standard and high-fat diets. Initially five rats each were given 10 mg/kg of each agent orally, and using serial blood withdrawals from jugular vein cannulas, the blood samples were assayed for drug and basic pharmacokinetic data estimated using compartmental analysis. A separate group of male and female rats were given the same single dose after either 10 (pimozide) or 13 (PSSI-51) weeks of feeding with a standard or high-fat diet, followed by two blood samples after each dose from the saphenous vein. Bayesian forecasting in conjunction with the mean and variance of pharmacokinetic parameters and assay coefficient of variation, was used to estimate the pharmacokinetic parameters in these rats. The two drugs differed in their optimal pharmacokinetic model (pimozide one compartment, PSSI-51 two compartment). Both drugs possessed a high volume of distribution (Vd/F), but the oral clearance (CL/F) of PSSI-51 was much higher than that of pimozide, in line with earlier observations using rat microsomal experiments. The high-fat diet significantly reduced the oral CL and Vd of PMZ in both male and female rats, whereas no such effect was observed for PSSI-51.
Advancing Quantitative ADA Detection Through Model Informed Assay Development (MIAD).
Jordan G, Staack RF
AAPS J · 2026 Jan · PMID 41577877 · Publisher ↗
Immunogenicity testing for anti-drug antibodies (ADAs) is crucial in therapeutic protein development, yet current quasi-quantitative assays struggle to accurately measure ADAs when the antibodies have different binding s...
Immunogenicity testing for anti-drug antibodies (ADAs) is crucial in therapeutic protein development, yet current quasi-quantitative assays struggle to accurately measure ADAs when the antibodies have different binding strength (affinities) or due to heterogeneity of ADAs and residual drug interference. While traditional QC-based assay development is limited by the lack of representative ADA reference standards, we propose Model-Informed Assay Development (MIAD) as a transformative solution. MIAD mathematically simulates complex analyte-reagent interactions to identify optimal conditions for signal-generating analyte-reagent complex (ARC) formation, enabling scientifically sound assay optimization independent of positive controls. Our findings demonstrate that optimal sample dilution and reagent concentrations can overcome drug interference and improved detection of antibodies (ADAs) with different binding strengths. This work applies MIAD to address critical ADA assay challenges: drug tolerance and affinity-dependent detectability. We tested MIAD's prediction in three real world case studies and found strong agreement. Our findings show that optimized sample dilutions and reagent concentrations effectively overcome drug interference and affinity differences, enhancing ADA detectability and recovery. MIAD also helps understanding whether a hook-shaped curve is due to a prozone effect or drug interference, guiding the development of unbiased assays crucial for accurate S/N-based magnitude estimation.
Glycan Profiles of FDA-Approved Therapeutic Antibodies: Insights from Regulatory Submissions.
Luo S, Hess K, Rogstad S … +1 more , Zhang B
AAPS J · 2026 Jan · PMID 41577853 · Publisher ↗
Glycosylation is a critical quality attribute of certain therapeutic proteins, influencing efficacy, safety, and pharmacokinetics. This study analyzed glycan characterization data and drug substance release specification...
Glycosylation is a critical quality attribute of certain therapeutic proteins, influencing efficacy, safety, and pharmacokinetics. This study analyzed glycan characterization data and drug substance release specifications from 209 Biologics License Applications (BLAs) approved by the U.S. Food and Drug Administration (FDA) through May 2025. Ten predominant Fc N-glycans were identified across IgG antibodies expressed by CHO, NS0, and Sp2/0 cell lines, with six glycans common to all systems. Five low-abundance afucosylated glycans (< 10%) were tightly controlled within drug substance release specifications for antibodies with Fc effector functions, although acceptance criteria varied across products. Glycan profiles were strongly dependent on the expression system: CHO-derived antibodies predominantly contained human-compatible glycan structures, whereas NS0 and Sp2/0 antibodies introduced non-human epitopes. Fc fusion proteins exhibited higher branching and sialylation compared with conventional IgG antibodies. Notably, analysis of product labels revealed that Fc effector functions were described exclusively as in vitro observations or proposed mechanisms, with limited clinical validation. Overall, these findings establish a comprehensive benchmark for glycan profiles of FDA-approved therapeutic antibodies and underscore the need for harmonized control strategies and stronger correlation between in vitro Fc assays and clinical outcomes.
Retrieval Augmented Generation (RAG) for Natural Language Querying of Immunogenicity Data for Protein Drugs.
Advani N, Bhat AG, Balu-Iyer S … +1 more , Ramanathan M
AAPS J · 2026 Jan · PMID 41566090 · Publisher ↗
To evaluate the strengths and limitations of retrieval-augmented generative (RAG) artificial intelligence (AI) for natural language querying of biologics immunogenicity data. The package inserts for drugs approved with b...
To evaluate the strengths and limitations of retrieval-augmented generative (RAG) artificial intelligence (AI) for natural language querying of biologics immunogenicity data. The package inserts for drugs approved with biologics license applications (BLA) were retrieved from DailyMed ( https://dailymed.nlm.nih.gov/dailymed/ ). The RAG system integrated natural language processing, retrieval, and large language model (LLM) components. ChatGPT, Gemini, DeepSeek, and Llama were queried with five clinical pharmacology-focused questions on factors influencing anti-drug antibody (ADA) incidence and tolerability, including effects of target protein, administration route, and citrate excipients. Outputs were assessed for relevance, faithfulness, and domain-specific accuracy. The dataset included 663 biologics, of which 206 (31.1%) were monoclonal antibodies. The RAG system retrieved relevant contexts for all queries, but several contexts contained inaccuracies related to the presence of non-antibody protein drugs. All four LLMs generated coherent summaries and identified determinants of ADA incidence, such as drug type, assay methods, and concomitant therapy. All models found that injection-site pain occurred with some protein therapeutics containing citrate excipients, and that evidence for a direct causal role of citrate was mixed. Comparative evaluation showed that LLM outputs were generally relevant and faithful to the source text, with variation in the level of detail and comprehensiveness across models. Domain-specific evaluations indicated that responses accurately identified trends in immunogenicity and highlighted the knowledge gaps. While RAG-based systems can retrieve and synthesize immunogenicity assessments from multiple source documents, significant limitations were noted in this use case. The effectiveness of the retriever can limit RAG performance and warrant refinement.
Best practices in the application of parallelism for biomarker assay validation.
King L, Allinson J, Amaravadi L … +11 more , Kernstock R, Garofolo F, Gunsior M, Jones B, Mathews J, Neely R, Nelson R, Pepin MO, Shen H, Stevenson L, Voelker T
AAPS J · 2026 Jan · PMID 41530473 · Publisher ↗
An assessment of parallelism is critical for biomarker assays to confirm whether the assay recognizes the endogenous analyte similarly to the calibrator, the suitability of a surrogate calibrator matrix and the potential...
An assessment of parallelism is critical for biomarker assays to confirm whether the assay recognizes the endogenous analyte similarly to the calibrator, the suitability of a surrogate calibrator matrix and the potential need for a minimal required dilution. While the importance of parallelism has been raised in numerous publications there remains a lack of detail on how to conduct and interpret parallelism experiments, as well as some confusion between parallelism, dilution linearity, and spike recovery experiments. This best practice paper provides a detailed discussion of the reasons for conducting parallelism, as well as recommendations for when to conduct parallelism experiments, the number of samples needed, the selection of appropriate surrogate matrices, the interpretation of parallelism data, including graphical and statistical methods, and parallelism results reporting. It emphasizes the need for continuous evaluation of parallelism throughout the assay life cycle to ensure reliable measurement of the desired analyte within the context of use. Finally, a number of short case studies are provided to illustrate the application and interpretation of parallelism.
Multiplexed Immunophenotyping for Innate Activation Assessment Detects Single-Cell Responses to Immunomodulatory Nucleic Acid Impurities in Therapeutics.
Balsamo JA, Mendoza M, Kelly-Baker L … +2 more , G Thacker S, Verthelyi D
AAPS J · 2026 Jan · PMID 41513884 · Publisher ↗
Innate immune response modulating impurities (IIRMI) with adjuvant potential have emerged as important factors in the immunogenicity risk assessment of protein, peptide, and oligonucleotide therapeutics, particularly for...
Innate immune response modulating impurities (IIRMI) with adjuvant potential have emerged as important factors in the immunogenicity risk assessment of protein, peptide, and oligonucleotide therapeutics, particularly for follow-on products where minimal or no clinical studies are available. To assess the impact of differences in impurities on specific cell types, we developed a new IIRMI assay termed multiplexed immunophenotyping for innate activation assessment (MIIAA) that employs spectral flow cytometry to capture single-cell responses to drug products and potential impurities. This technique introduces a new live fluorescent cell barcoding platform that enables sample multiplexing for homogeneous staining with a single fluorescent antibody cocktail composed of identity and activation markers that are acquired simultaneously with a five laser Cytek Aurora. Samples are digitally reassigned to their original testing conditions by positive and negative gating of barcode dyes. Cellular subsets are identified by dimensionality reduction of surface markers with UMAP then gated using cell-specific markers. Here we use trace levels of TLR3, 7/8 and 9 agonists (Poly(I:C), R848, and CpG ODN) to characterize specific responses in B cells, monocytes, cDC and pDC. Importantly, MIIAA captures single-cell responses to nucleic acid impurities in the presence of therapeutic oligonucleotides or monoclonal antibodies with high sensitivity. Taken together, MIIAA offers a powerful immunophenotyping tool to characterize single-cell responses to drug products and potential immunomodulatory impurities that may find utility in drug pipelines to characterize the impact of therapeutics on specific immune cells and to interrogate immunogenic or immunomodulatory risk in comparisons between reference and follow-on products.
Anti-drug Antibody Validation Testing and Reporting Harmonization Addendum.
Myler H, Mora J, Pedras-Vasconcelos J … +5 more , Lavelle A, Chamberlain P, Pan L, Yang L, Kramer D
AAPS J · 2026 Jan · PMID 41507683 · Publisher ↗
The anti-drug antibody validation testing and reporting harmonization (ADAH) white paper was published December 2021 and has generated significant interest, highlighting its utility within the scientific community. Follo...
The anti-drug antibody validation testing and reporting harmonization (ADAH) white paper was published December 2021 and has generated significant interest, highlighting its utility within the scientific community. Following the ADAH white paper, members of the American Association of Pharmaceutical Scientist (AAPS) Therapeutic Product Immunogenicity community published a similar white paper addressing neutralizing antibody validation testing and reporting harmonization (NAbH) in July 2023 which has also been broadly accessed. Given the broad interest in these white papers by the bioanalytical and immunogenicity communities, the authors have solicited user feedback to address noted gaps. This feedback has prompted us to issue an addendum to address these gaps including adding a section on anti drug antibody (ADA) assay cross-validation and ADA data presentation for regulatory submissions, and to update the method sensitivity assessments. In addition, given recent year discussions around the implementation of signal to noise over titer, a section on this topic is included.
Virtual Twin-PBPK Modelling: A Step Toward Precision Dosing in Patients with Obesity.
Kangne H, Izat N, Chen G … +5 more , Ogungbenro K, Jansson-Löfmark R, Hertel JK, Robertsen I, Galetin A
AAPS J · 2026 Jan · PMID 41507668 · Publisher ↗
Obesity significantly alters drug disposition and contributes to large inter-individual variability in pharmacokinetics (PK). The virtual-twin concept is increasingly used to support model-informed precision dosing in sp...
Obesity significantly alters drug disposition and contributes to large inter-individual variability in pharmacokinetics (PK). The virtual-twin concept is increasingly used to support model-informed precision dosing in specific populations. In this study, physiologically-based pharmacokinetic models linked with virtual twins (VT-PBPK) have been developed and applied to predict the PK of midazolam and digoxin in patients with obesity (n = 15) and severe obesity (n = 22). The first step of the individualization included basic demographic data with lean liver volume. In the second step, individual serum creatinine, albumin, and hepatic CYP3A4/5, UGT1A4 and P-gp abundance quantified from liver biopsies in the same individuals, were integrated within models. Substrate specific improvements were presented via the stepwise individualization. The final (Step 2) VT-PBPK models predicted midazolam AUC within 2-fold for 86% of the individuals (geometric mean fold error, GMFE = 1.5; 95% confidence interval (CI95) = 1.36-1.78), with 36% within the 0.8 to 1.25-fold of the observed values. For digoxin, 97% of C and AUC values were predicted within 2-fold of the observed data (GMFE = 1.25; CI95 = 1.19-1.33), with 59% of predicted values within the 0.8-1.25-fold range. In the case of digoxin, the prediction accuracy was higher for patients with severe obesity (60% of C and AUC values within the 1.25-fold range); no clear trends were evident for midazolam. This is the first study that applied the VT-PBPK modelling approach in patients with obesity. It highlights the potential of this approach to predict the PK of other CYP3A and P-gp substrates to support individual dose optimization in this population.
The Influence of Routes of Administration on 3-chloromethcathinone Urinary Biomarkers Disposition: Preliminary In Vivo Study of Unknown Metabolites Profiling on Healthy Volunteers.
Di Trana A, La Maida N, Graziano S … +7 more , Pichini S, Hladun O, Poyatos L, Ventura M, Papaseit E, Farré M, Perez-Maña C
AAPS J · 2026 Jan · PMID 41507461 · Publisher ↗
In 2024, 3-Chloromethcathinone (3-CMC) accounted for over 63% of all New Psychoactive Substances seized in Europe, yet its human pharmacology remains poorly understood. This observational, uncontrolled, naturalistic stud...
In 2024, 3-Chloromethcathinone (3-CMC) accounted for over 63% of all New Psychoactive Substances seized in Europe, yet its human pharmacology remains poorly understood. This observational, uncontrolled, naturalistic study involved 16 regular psychostimulant users to evaluate and compare 3-CMC metabolism, and distribution in urine and oral fluid (OF) following oral and intranasal administration. Two groups, each consisting of 8 participants (6 males, 2 females) self-administered 3-CMC in two separate sessions: 100-150 mg orally and 60-80 mg intranasally. Urine was collected in two pooled intervals (0-2 h and 2-5 h). Samples were analyzed via four untargeted HPLC-HRMS/MS methods in full MS and ddMS to characterize the unknown metabolites supported by Compound Discoverer™ software with an established workflow. The data were grouped into four groups concerning the route of administration and the time intervals and the average area were statistically compared with a one-way ANOVA. The parent drug was detected in all the samples at different levels. In total, nine metabolites were observed, of those 4 were phase I and 5 phase II metabolites. Considering the route of administration, distinct metabolic patterns emerged: three metabolites, including two N-acetylated forms and a carboxylated metabolite, were found only after oral intake, suggesting N-acetylation occurs primarily via this route. In contrast, β-OH-3-CMC accumulated more after intranasal use. Furthermore, 3-CMC N- glucuronidation was hypothesized for the first time. These findings indicate that the administration route significantly influences 3-CMC metabolism, highlighting the need for tailored forensic and toxicological assessments.
Target Abundance in Pharmacological Target-Mediated Drug Disposition (TMDD) for Small Molecules - A Proteomics Approach.
Xu M, Yuan X, Li P … +3 more , Bach T, Zhu HJ, An G
AAPS J · 2026 Jan · PMID 41495534 · Publisher ↗
The phenomenon of nonlinear pharmacokinetics (PK) mediated by a drug's pharmacological target, also known as target-mediated drug disposition (TMDD), has been increasingly observed in small molecules in the past decade....
The phenomenon of nonlinear pharmacokinetics (PK) mediated by a drug's pharmacological target, also known as target-mediated drug disposition (TMDD), has been increasingly observed in small molecules in the past decade. TMDD class effect with remarkably similar nonlinear PK behaviors has been reported in 11β-hydroxysteroid dehydrogenase type 1 (11β-HSD1) inhibitors, monoamine oxidase type B (MAO-B) inhibitors, and soluble epoxide hydrolase (sEH) inhibitors. We anticipated that the occurrence of TMDD class effect might be due to their target capacities falling within a specific range, where nonlinear PK mediated by target binding are more likely to be evident. To test our hypothesis, we employed a mass spectrometry (MS)-based global proteomics approach to quantify the absolute protein concentrations of 11β-HSD1, sEH, and MAO-B in different tissues across species. The estimated total amounts of 11β-HSD1, MAO-B, and sEH in humans were approximately 4994, 4629, and 4137 nmol, respectively. The comparable abundance levels of these proteins suggest that TMDD is more likely to be observed when a drug binds to a target within a specific range, potentially between 1000 nmol and 10000 nmol, which corresponds to nonlinear PK at doses of 1-10 mg for a compound with a molecular weight of 400 g/mol. Our study highlights the importance of early target quantification and provides valuable insights into predicting unusual nonlinear PK caused by TMDD. Additionally, this proteomics-based approach for quantifying absolute target capacity could serve as a valuable tool for both industry and academic researchers in investigating other pharmacological targets.
Investigation of Monoclonal Antibody Pharmacokinetics in Pediatric Population and Characterization Using a Platform PBPK Model.
Kumar M, Lanke S, Shah DK
AAPS J · 2026 Jan · PMID 41491850 · Publisher ↗
This study aimed to investigate the impact of age on pediatric PK of mAbs and develop a platform PBPK model to support optimal dosing of mAbs in pediatric patients. After extensive literature review 49 mAbs were identifi...
This study aimed to investigate the impact of age on pediatric PK of mAbs and develop a platform PBPK model to support optimal dosing of mAbs in pediatric patients. After extensive literature review 49 mAbs were identified as approved for pediatric use, but only 17 had adequate PK data to support the investigation. It was found that pediatric patients exhibit 20-40% lower initial concentration (i.e. C) compared to adults following the same body weight normalized dose. For mAbs demonstrating linear PK, a similar rate of bodyweight normalized clearance was observed between adult and pediatric patients aged 2 years and above, while a faster clearance per kg bodyweight (up to 45% higher) was seen for infants and neonates. The majority of mAbs that demonstrate nonlinear PK were found to have faster bodyweight normalized clearance (up to 350% higher) in pediatric patients. A platform PBPK model was developed to characterize the PK of mAbs in pediatric patients across all age groups. The model was able to adequately (%PE < 35) characterize plasma PK of 11 mAbs with linear PK in pediatric patients aged 0.13 to 17 years following intravenous or subcutaneous administration. The developed model was able to apriori predict antibody PK reasonably well (%PE < 35). The PBPK model was integrated into an interactive web-based R Shiny application ( http://40.67.147.7/ ). The app allows individuals with minimal pharmacometrics expertise to simulate the PK of mAbs in pediatric patients and personalize the dosing of mAbs in patients with sparse PK data from therapeutic drug monitoring.
Assessment of Immune Responses Against AAV Encoded Transgene Products.
Gorovits B, Azadeh M, Fiscella M … +18 more , Harrison T, Hofer M, Janetzki S, Jawa V, Long B, Lu Y, Mahnke YD, Maia M, Majumdar R, Miller M, Milton M, Nelson R, Partridge MA, Shaik S, Snoeck V, Vettermann C, Wu B, Zhao A
AAPS J · 2026 Jan · PMID 41491260 · Publisher ↗
The number of clinical investigations and approved applications of adeno-associated virus (AAV) based transgene product (TP) delivery has grown steadily. There also has been a growing interest in understanding how anti-A...
The number of clinical investigations and approved applications of adeno-associated virus (AAV) based transgene product (TP) delivery has grown steadily. There also has been a growing interest in understanding how anti-AAV and anti-TP immune responses affect the safety and efficacy of these gene therapy treatments. While considerations related to anti-AAV immunity have been discussed in other works, this manuscript focuses on the assessment of anti-TP immune responses, including both humoral and cellular responses. The development of anti-TP antibodies or a cytotoxic cellular response may lead to increased clearance of the TP, elimination of AAV-transduced cells, and consequently, affect the overall durability and efficacy of the treatment. Additionally, the binding and neutralization of residual endogenous protein by anti-TP antibodies might further worsen the clinical condition under treatment. Several topics are explored in this manuscript, including immunogenicity risk factors that can be considered when evaluating the overall risk and impact of anti-TP immunogenicity, potential implications of anti-TP immunogenicity, the importance of assessing anti-TP immunogenicity, and the commonly used analytical methodologies. The manuscript proposes an approach to determining the scope of anti-TP immunogenicity assessment for clinical and non-clinical studies, based on the TP nature, other intrinsic and extrinsic risk factors. Authored by a group of scientists involved in AAV-based therapeutic development from various industry organizations, the manuscript aims to provide recommendations and guidance to industry sponsors, academic laboratories, and regulatory agencies working on AAV-based modalities, with the goal of achieving a more consistent approach to the assessment of anti-TP immune response.
Exploration of IVIVC Deconvolution Methods in a PBPK Platform: Case Example with Tofacitinib.
Hens B
AAPS J · 2026 Jan · PMID 41491139 · Publisher ↗
Modified-release (MR) drug products are designed to provide controlled drug delivery over time, offering therapeutic and compliance advantages. However, ensuring consistent in vivo performance requires a thorough underst...
Modified-release (MR) drug products are designed to provide controlled drug delivery over time, offering therapeutic and compliance advantages. However, ensuring consistent in vivo performance requires a thorough understanding of the relation between in vitro dissolution behavior and in vivo drug absorption. In vitro-in vivo correlation (IVIVC) serves as a critical tool in this context, enabling formulation optimization, supporting regulatory decision-making, and streamlining product development. This study aimed to use tofacitinib as a model compound to evaluate three deconvolution methodologies within GPX™ - numerical, compartmental, and mechanistic. Prototype formulations with varying release rates were assessed in a randomized crossover study in healthy volunteers. In vivo fraction absorbed profiles were derived and convoluted to simulate plasma concentration-time profiles, which were then compared to observed clinical data. Prediction errors for key pharmacokinetic parameters (i.e., plasma C and AUC) were determined, and 90% confidence intervals for both parameters were calculated to assess bioequivalence between the simulated (convoluted) and observed plasma profiles. The results demonstrate the utility of deconvolution-based IVIVC models for MR product development in a physiologically-based pharmacokinetic (PBPK) framework and offer a strategy for assessing dissolution variability in support of regulatory flexibility and robust formulation lifecycle management.
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