Accurate predictions of complex clinical drug-drug interactions (DDIs), arising from dual induction and time-dependent inhibition (TDI) of CYP3A4, has remained challenging with conventional in vitro and static/dynamic modeling approaches. In this work, we aimed to anticipate the hepatic DDI effects of 6 CYP3A4 precipitant drugs using a liver-chip coupled to microfluidic perfusion, which enabled simulating clinically relevant pharmacokinetic (PK) time-concentration profiles. Midazolam clearance was measured in the liver-chip to determine the CYP3A4-mediated DDI net effect following exposure to precipitants under either dynamic or constant concentration conditions. For direct comparison, hepatic DDI reference values were generated based on clinical DDI studies by physiologically based PK modeling. Under microfluidic perfusion, CYP3A4 activity in the liver-chip was retained for 3 days and inducible by rifampicin. Although most precipitant drugs induced CYP3A4 mRNA levels, CYP3A4 activity net effects showed either induction or inhibition, in line with clinical observations. Compared with a mechanistic static net effect model and physiologically based PK simulations, liver-chip predictions showed closer alignment and higher accuracy relative to hepatic reference values. Although constant exposures offered the strongest quantitative performance, the ability to apply dynamic PK profiles represents a distinctive feature of this platform. Collectively, these findings position the human liver-chip as a novel translational platform for predicting complex hepatic CYP3A4 DDIs arising from dual TDI and induction in a single, holistic in vitro model. This approach aligns with the broader global regulatory shift toward human-relevant new approach methodologies. SIGNIFICANCE STATEMENT: Complex CYP3A4-mediated drug-drug interactions (DDIs), driven by concurrent time-dependent inhibition and induction, remain difficult to anticipate using conventional in vitro and modeling frameworks. This study establishes a human liver-chip model capable of capturing dual CYP3A4 inhibition and induction within a single experiment, and evaluates how clinical exposure regimes shape the quantitative prediction of hepatic DDI effects. Relative to modeling approaches, this platform demonstrates superior accuracy against hepatic DDI references, supporting more translational DDI risk assessments.

The use of mechanistic static and dynamic physiologically based pharmacokinetic (PBPK) models by incorporating CYP3A4/5-mediated time-dependent inhibition (TDI) parameters from human liver microsomes (HLM) can potentially give rise to significant overprediction of drug-drug interactions (DDI) caused by TDI, which may result in conducting unnecessary clinical DDI trials. This work aimed to evaluate the predictive performance of mechanistic static and dynamic PBPK models employed to predict the likelihood and the magnitude of clinical DDI caused by drugs with in vitro CYP3A4/5 TDI parameters measured in HLM and human hepatocytes (HHEPs). We examined the effect of differences in in vitro CYP3A4/5 TDI parameters such as the inhibition constant (total or unbound) in experimental conditions (supplementation of glutathione in HLM incubations or plasma in HHEP incubations) on the magnitude of predicted DDI risk in comparison to clinical results. In mechanistic static models, the average unbound organ exit concentrations and the maximum organ entry concentrations were compared for projecting DDI risks. Model performance was assessed using false-negative rates and negative predictive errors for a cutoff value of either 1.25- or 2-fold change in midazolam exposure. DDI caused by CYP3A4/5-mediated TDI was reliably predicted using mechanistic static model with average unbound organ exit concentrations or dynamic PBPK modeling, yielding less marked overpredictions of DDI. Models using in vitro inhibition constant corrected for incubation unbound fraction generated in either HLM or HHEP buffer incubations showed best statistical performance while maintaining high prediction accuracy and precision. SIGNIFICANCE STATEMENT: CYP3A4/5 time-dependent inhibition can lead to drug-drug interactions. CYP3A4 time-dependent inhibition parameters for 15 drugs, known as in vitro time-dependent inhibitors, were measured using various experimental conditions. These data were used in mechanistic static and physiologically based pharmacokinetic models to predict drug-drug interactions and identify false positives from in vitro experiments.

ABSTRACT The risk of clinically relevant drug–drug interactions (DDIs) for therapeutic peptides remains unclear, mandating a comprehensive analysis for this modality. In our prior study, we analyzed DDIs for 31 peptide drugs approved between January 2008 and August 2021. Here, we analyze DDI data for an additional nine peptide drugs (trofinetide, nirmatrelvir, danicopan, odevixibat, rezafungin, motixafortide, zilucoplan, vosoritide, and tirzepatide) approved from September 2021 to September 2024, focusing on in vitro and clinical DDI data for metabolism‐ and transporter‐based interactions. All nine peptides investigated CYP inhibition in human liver microsomes (HLMs), with low risk identified for larger peptides (> 2 kDa). Likewise, all nine peptides assessed CYP induction in human hepatocytes, with one peptide showing a risk in vitro (danicopan). Phenotyping investigations varied from standard studies (e.g., HLMs with selective CYP inhibitors) to submission packages without classical phenotyping studies. All nine peptides included information related to in vitro transporter properties, but the level of detail varied between submitted packages. Clinical studies investigating metabolism‐ or transporter‐mediated DDIs were performed for four peptides (all < 2 kDa). Area under the curve changes attributed to the peptide drug were < 2.3 fold. Our expanded dataset now includes 40 therapeutic peptides approved since 2008, providing a unique resource for drug developers. The findings reinforce our previous conclusions regarding the low likelihood of DDIs for larger peptides and a higher risk for smaller peptides with xenobiotic structural properties. This collective data will be invaluable in developing clear and meaningful DDI guidelines for therapeutic peptides.

Ribociclib is an orally bioavailable, selective cyclin-dependent kinase 4 and 6 (CDK4/6) inhibitor. CDK4/6 inhibition by ribociclib leads to retinoblastoma tumor suppressor protein (Rb) reactivation, thereby restoring Rb-mediated cell cycle arrest. Ribociclib is approved for the treatment of patients with hormone receptor-positive/human epidermal growth factor receptor-2-negative (HR+/HER2−) advanced breast cancer (ABC), at the dose of 600 mg once daily (QD) during cycles of 21 days on/7 days off, with optional dose reduction to 400 mg and 200 mg. Ribociclib is rapidly absorbed with a median time to reach maximum plasma concentration of 2.4 h, mean half-life of 32.0 h and oral bioavailability of 65.8% at 600 mg. It is eliminated mainly by hepatic metabolism (~ 84% of total elimination), mostly by cytochrome P450 (CYP) 3A4. Age, body weight, race, baseline Eastern Cooperative Oncology Group status, food, mild hepatic impairment, mild-to-moderate renal impairment, proton pump inhibitors, and combination partners (non-steroidal aromatase inhibitors or fulvestrant) have no clinically relevant impact on ribociclib exposure. Ribociclib inhibits CYP3A at 600 mg leading to increased exposure of CYP3A substrates. Strong CYP3A inhibitors or inducers increase or decrease, respectively, ribociclib exposure. Exposure-safety and exposure-efficacy analyses support the clinical benefit of the 600 mg QD starting dose, with potential individualized dose reductions to 400 mg and 200 mg for effective management of the adverse events neutropenia and QTcF interval prolongation, while maintaining efficacy, in patients with HR+/HER2− ABC. Overall, these clinical pharmacology data informed ribociclib dose justification and clinical development, as well as its prescribing information for clinical use in advanced breast cancer patients.

Drug-drug interaction (DDI) assessments are well defined in health authority guidelines for small molecule drugs, and US Food and Drug Administration (FDA) draft guidance is now available for therapeutic proteins. However, there are currently no regulatory guidelines outlining DDI assessments for therapeutic peptides, which poses significant uncertainty and challenges during drug development for this heterogenous class of molecules. A cross-industry peptide DDI working group consisting of experts from 10 leading companies was formed under the sponsorship of the European Federation of Pharmaceutical Industries and Associations. We aimed to capture the range of DDI studies undertaken for peptide drugs by (i) anonymously surveying relevant companies involved in peptide drug development to better understand DDI study type/timing currently performed and (ii) compiling a database containing in vitro / clinical DDI data from submission packages for recently approved peptide drugs. Our analyses highlight significant gaps and uncertainty in the field. For example, the reported timing of in vitro peptide DDI studies, if performed, vary substantially across responding companies from early research to phase III. Nearly all in vitro cytochrome P450 / transporter inhibition studies reported in the survey were negative. For the few positive hits reported, no clinical follow-up studies were performed, questioning the clinical relevance of these findings. Furthermore, available submission packages reveal DDI likelihood is low for peptides >2 kDa, making it reasonable to adopt a risk-based approach during drug development for larger peptides. By benchmarking the landscape of peptide DDI activities across the industry, we set the stage for future discussions with health authorities on harmonizing peptide DDI approaches.

This annual review is the eighth of its kind since 2016 (Baillie et al. 2016, Khojasteh et al. 2017, Khojasteh et al. 2018, Khojasteh et al. 2019, Khojasteh et al. 2020, Khojasteh et al. 2021, Khojasteh et al. 2022). Our objective is to explore and share articles which we deem influential and significant in the field of biotransformation.

Typically, therapeutic proteins (TPs) have a low risk for eliciting meaningful drug interactions (DIs). However, there are select instances where TP drug interactions (TP-DIs) of clinical concern can occur. This white paper discusses the various types of TP-DIs involving mechanisms such as changes in disease state, target-mediated drug disposition, neonatal Fc receptor (FcRn), or antidrug antibodies formation. The nature of TP drug interaction being investigated should determine whether the examination is conducted as a standalone TP-DI study in healthy participants, in patients, or assessed via population pharmacokinetic analysis. DIs involving antibody-drug conjugates are discussed briefly, but the primary focus here will be DIs involving cytokine modulation. Cytokine modulation can occur directly by certain TPs, or indirectly due to moderate to severe inflammation, infection, or injury. Disease states that have been shown to result in indirect disease-DIs that are clinically meaningful have been listed (i.e., typically a twofold change in the systemic exposure of a coadministered sensitive cytochrome P450 substrate drug). Type of disease and severity of inflammation should be the primary drivers for risk assessment for disease-DIs. While more clinical inflammatory marker data needs to be collected, the use of two or more clinical inflammatory markers (such as C-reactive protein, albumin, or interleukin 6) may help broadly categorize whether the predicted magnitude of inflammatory disease-DI risk is negligible, weak, or moderate to strong. Based on current knowledge, clinical DI studies are not necessary for all TPs, and should no longer be conducted in certain disease patient populations such as psoriasis, which do not have sufficient systemic inflammation to cause a meaningful indirect disease-DI.

Remibrutinib, a novel oral Bruton's Tyrosine Kinase inhibitor (BTKi) is highly selective for BTK, potentially mitigating the side effects of other BTKis. Enzyme phenotyping identified CYP3A4 to be the predominant elimination pathway of remibrutinib. The impact of concomitant treatment with CYP3A4 inhibitors, grapefruit juice and ritonavir (RTV), was investigated in this study in combination with an intravenous microtracer approach. Pharmacokinetic (PK) parameters, including the fraction absorbed, the fractions escaping intestinal and hepatic first-pass metabolism, the absolute bioavailability, systemic clearance, volume of distribution at steady-state, and the fraction metabolized via CYP3A4 were evaluated. Oral remibrutinib exposure increased in the presence of RTV 4.27-fold, suggesting that remibrutinib is not a sensitive CYP3A4 substrate. The rich PK dataset supported the building of a robust physiologically-based pharmacokinetic (PBPK) model, which well-described the therapeutic dose range of 25-100 mg. Simulations of untested scenarios revealed an absence of drug-drug interaction (DDI) risk between remibrutinib and the weak CYP3A4 inhibitor fluvoxamine (area under the concentration-time curve ratio [AUCR] <1.25), and a moderate effect with the CYP3A4 inhibitor erythromycin (AUCR: 2.71). Predictions with the moderate and strong CYP3A4 inducers efavirenz and rifampicin, suggested a distinct remibrutinib exposure decrease of 64% and 89%. Oral bioavailability of remibrutinib was 34%. The inclusion of an intravenous microtracer allowed the determination of all relevant remibrutinib PK parameters, which facilitated construction of the PBPK model. This will provide guidance on the selection or restriction of comedications and prediction of DDI risks.

PURPOSE:Pharmacokinetic drug-drug interactions (DDIs) are investigated to ensure safety for patients receiving concomitant medications. Here, we present a strategy to characterise the DDI potential of remibrutinib, as an inhibitor of drug-metabolising enzymes and drug transporters, and as an inducer. Initial in vitro studies were performed, followed by a biomarker-based assessment of induction in a first in human study, concluded by a clinical study to verify initial results. Remibrutinib is a covalent inhibitor of Bruton's Tyrosine kinase (BTKi) carrying a reactive acrylamide moiety (warhead), thus the potential contribution of covalent binding (off-target) to observed interactions was investigated as this could lead to prolonged and more potent drug interactions.METHODS:DDI assessment was focused on the putative inhibition of key metabolic enzymes (Cytochrome P450, CYP), drug transporters and a potential effect on oral contraceptives (OC) by induction of enzymes that are involved in their clearance (CYP3A4). The impact of covalent binding was assessed by synthesising an identical reference molecule but with an inactivated warhead.RESULTS:An interaction potential of limited clinical relevance was revealed for remibrutinib for CYP enzymes and drug transporters. The reactive warhead of remibrutinib had no impact on CYP enzyme and transporter inhibition, including time-dependent inhibition of CYP3A4, but may increase the induction potential of remibrutinib.CONCLUSIONS:Observed inhibition of metabolic enzymes indicated that remibrutinib is a weak inhibitor of CYP3A4 and CYP2C9 and is not a clinically relevant inhibitor of uptake and efflux transporters, except for intestinal P-glycoprotein and breast cancer resistance protein inhibition. OC may be safely administered and are effective when given with pharmacologically relevant doses of remibrutinib.

LSZ102 is an orally bioavailable selective oestrogen receptor degrader in clinical development for the treatment of breast cancer. Preclinical studies showed efficacy in xenograft models on oral dosing. However, oral bioavailability was relatively low in several preclinical species (7-33%), and was associated with first-pass metabolism, particularly intestinal first-pass. To investigate metabolism and first-pass effects, metabolites were analysed in human plasma samples after oral dosing of LSZ102 to patients, rat plasma samples after oral dosing of [C-14]LSZ102, and in vitro incubations of [C-14]LSZ102 with human and rat hepatocytes and intestinal S9 fractions. The kinetics of human sulfotransferase (SULT) enzymes potentially involved in metabolism of LSZ102 was characterised. Sulphate metabolites were found to be the major components in human plasma, as well as in human hepatocytes and intestinal S9 fractions. Contrastingly, glucuronidation was predominant in rat plasma, hepatocytes and intestinal S9. LSZ102 was found to be metabolised by several human SULTs expressed in liver and intestine. The combined metabolism data in rat and human provide supporting evidence for an extensive intestinal first-pass metabolism effect via sulphation in human but glucuronidation in rat. As LSZ102 is metabolised by a number of different SULTs, drug-drug interactions resulting from the inhibition of one SULT are unlikely. Despite the observed species difference in metabolism, the major human metabolites of LSZ102, sulphate M5, glucuronide M4, and secondary glucuronide/sulphate metabolite M12, have no or weak pharmacological activity and are not considered a toxicity risk as they are phase II conjugative metabolites.

Ribociclib is approved in combination with endocrine therapy as initial endocrine-based therapy for HR+, HER2- advanced breast cancer. Ribociclib is primarily metabolized by CYP3A4 and, in vitro, is an inhibitor of CYP3A and CYP1A2. Ritonavir (a strong CYP3A inhibitor) increased ribociclib 400 mg single-dose AUC by 3.2-fold, whereas rifampin (a strong CYP3A inducer) decreased ribociclib AUC by 89% in healthy volunteers (HV). Multiple 400 mg ribociclib doses increased midazolam (CYP3A substrate) AUC by 3.8-fold and caffeine (CYP1A2 substrate) AUC by 1.2-fold versus each agent alone. A physiologically based pharmacokinetic (PBPK) model was developed integrating in vitro, preclinical, and clinical data of HV and cancer patients. Data predictions indicated that multiple 600 mg ribociclib doses increased midazolam AUC by 5.2-fold and ritonavir increased ribociclib 600 mg multiple dose AUC by 2.90-fold in cancer patients. Based on pharmacokinetics, safety and efficacy data, and PBPK modeling, dosing modifications for ribociclib recommend avoiding concurrent use of strong CYP3A inhibitors/inducers, and caution regarding using CYP3A substrates with narrow therapeutic indices.

Abstract Ribociclib (LEE011, Kisqali ®) is a highly selective small molecule inhibitor of cyclin‐dependent kinases 4 and 6 (CDK4/6), which has been approved for the treatment of advanced or metastatic breast cancer. A human ADME study was conducted in healthy male volunteers following a single oral dose of 600 mg [14C]‐ribociclib. Mass balance, blood and plasma radioactivity, and plasma ribociclib concentrations were measured. Metabolite profiling and identification was conducted in plasma, urine, and feces. An assessment integrating the human ADME results with relevant in vitro and in vivo non‐clinical data was conducted to provide an estimate of the relative contributions of various clearance pathways of the compound. Ribociclib is moderately to highly absorbed across species (approx. 59% in human), and is extensively metabolized in vivo, predominantly by oxidative pathways mediated by CYP3A4 (ultimately forming N‐demethylated metabolite M4) and, to a lesser extent, by FMO3 (N‐hydroxylated metabolite M13). It is extensively distributed in rats, based on QWBA data, and is eliminated rapidly from most tissues with the exception of melanin‐containing structures. Ribociclib passed the placental barrier in rats and rabbits and into milk of lactating rats. In human, 69.1% and 22.6% of the radiolabeled dose were excreted in feces and urine, respectively, with 17.3% and 6.75% of the 14C dose attributable to ribociclib, respectively. The remainder was attributed to numerous metabolites. Taking into account all available data, ribociclib is estimated to be eliminated by hepatic metabolism (approx. 84% of total), renal excretion (7%), intestinal excretion (8%), and biliary elimination (1%).

Ribociclib is approved in combination with endocrine therapy as initial endocrine‐based therapy for HR‐positive and HER2‐negative advanced breast cancer. Ribociclib is primarily metabolized by CYP3A4 and, in vitro, is an inhibitor of CYP3A and CYP1A2. Ritonavir (a strong CYP3A inhibitor) increased ribociclib 400 mg single‐dose area under the plasma concentration‐time curve (AUC) by 3.2‐fold, whereas rifampin (a strong CYP3A inducer) decreased ribociclib AUC by 89% in healthy volunteers (HVs). Multiple 400 mg ribociclib doses increased midazolam (CYP3A substrate) AUC by 3.8‐fold and caffeine (CYP1A2 substrate) AUC by 1.2‐fold vs. each agent alone. A physiologically‐based pharmacokinetic (PBPK) model was developed integrating in vitro, preclinical, and clinical data of HVs and patients with cancer. Data predictions indicated that multiple 600 mg ribociclib doses increased midazolam AUC by 5.85‐fold and ritonavir increased ribociclib 600 mg multiple dose AUC by 1.31‐fold in cancer patients. Based on pharmacokinetics, safety, and efficacy data, and PBPK modeling, dosing modifications for ribociclib recommend avoiding concurrent use of strong CYP3A inhibitors/inducers, and caution regarding using CYP3A substrates with narrow therapeutic indices.

Fevipiprant, a prostaglandin D-2 receptor 2 antagonist, is in clinical development as a treatment for asthma. The goal of this study was to assess the potential of fevipiprant to cause drug-drug interactions (DDI) as a perpetrator, that is, by altering the pharmacokinetics (PK) of co-medications. In vitro drug interaction studies of clinically relevant drug metabolizing enzymes and transporters were conducted for fevipiprant and its acyl glucuronide (AG) metabolite. Comparison of K-i values with unbound systemic or portal vein steady-state plasma exposure of fevipiprant and its AG metabolite revealed the potential for inhibition of organic anion transporting polypeptide 1B1 (OATP1B1) transporters (R-value of 5.99), while other targets including cytochrome P450 enzymes were not, or only marginally, inhibited. Consequently, an open-label, two-part, two-period, single-sequence clinical study assessed the effect of fevipiprant 450 mg QD on the pharmacokinetics of simvastatin 20 mg and rosuvastatin 20 mg, two statins with different dependency in OATP1B1-mediated hepatic uptake, in healthy adult volunteers. The study also assessed the pharmacogenetics of the SLCO1B1 gene, which encodes OATP1B1. Clinically, fevipiprant 450 mg QD showed a low potential for interaction and increased the peak concentrations of simvastatin acid and rosuvastatin by 2.23- and 1.87-fold, respectively, with little or no impact on total exposure. Genotype analysis confirmed that SLCO1B1 genotype influences statin pharmacokinetics to a similar extent either with or without fevipiprant co-administration. In summary, fevipiprant at 450 mg QD has only minor liabilities as a perpetrator for DDI.

Abstract Ruxolitinib is mainly metabolized by cytochrome P450 (CYP) enzymes CYP3A4 and CYP2C9 followed by minor contributions of other hepatic CYP enzymes in vitro. A physiologically based pharmacokinetic (PBPK) model was established to evaluate the changes in the ruxolitinib systemic exposures with co-administration of CYP3A4 and CYP2C9 perpetrators. The fractions metabolized in the liver via oxidation by CYP enzymes (fm,CYP3A4 = 0.75, fm,CYP2C9 = 0.19, and fm,CYPothers = 0.06) for an initial ruxolitinib model based on in vitro data were optimized (0.43, 0.56, and 0.01, respectively) using the observed exposure changes of ruxolitinib (10 mg) with co-administered ketoconazole (200 mg). The reduced amount of fm,CYP3A4 was distributed to fm,CYP2C9. For the initial ruxolitinib model with co-administration of ketoconazole, the area under the curve (AUC) increase of 2.60-fold was over-estimated compared with the respective observation (1.91-fold). With the optimized fm values, the predicted AUC ratio was 1.82. The estimated AUC ratios of ruxolitinib by co-administration of the moderate CYP3A4 inhibitor erythromycin (500 mg) and the strong CYP3A4 inducer rifampicin (600 mg) were within a 20% error compared with the clinically observed values. The PBPK modeling results may provide information on the labeling, i.e. supporting a dose reduction by half for co-administration of strong CYP3A4 inhibitors. Furthermore, an AUC increase of ruxolitinib in the absence or presence of the dual CYP3A4 and CYP2C9 inhibitor fluconazole (100–400 mg) was prospectively estimated to be 1.94- to 4.31-fold. Fluconazole simulation results were used as a basis for ruxolitinib dose adjustment when co-administering perpetrator drugs. A ruxolitinib PBPK model with optimized fm,CYP3A4 and fm,CYP2C9 was established to evaluate victim DDI risks. The previous minimal PBPK model was supported by the FDA for the dose reduction strategy, halving the dose with the concomitant use of strong CYP3A4 inhibitors and dual inhibitors on CYP2C9 and CYP3A4, such as fluconazole at ≤200 mg. Fluconazole simulation results were used as supportive evidence in discussions with the FDA and EMA about ruxolitinib dose adjustment when co-administering perpetrator drugs. Thus, this study demonstrated that PBPK modeling can support characterizing DDI liabilities to inform the drug label and might help reduce the number of clinical DDI studies by simulations of untested scenarios, when a robust PBPK model is established.