3A4 Inhibitors Research Articles

Clozapine Toxicity Predictor: Deep neural network model predicting clozapine toxicity and its therapeutic dose range

Clozapine is the gold standard for treatment-resistant schizophrenia; however, its superior efficacy is accompanied by potentially serious adverse events (neutropenia, seizures, constipations, pneumonia), many of which are also concentration-dependent. As such, clozapine dose titration should be guided by therapeutic drug monitoring (TDM). However, access to TDM is often limited. The present study describes a new deep neural network that can predict the concentrations, toxicity and therapeutic dose range for clozapine and norclozapine. The model was trained on basic clinical data (biological sex, age, clozapine daily dose, BMI, CRP and number of CYP 1A2 and 3A4 substrates, inhibitors and inducers) from 69 patients with treatment-refractory patients treated with different clozapine doses. Our findings provide the training efficacy data for the model, as well as an analysis of clozapine and norclozapine blood concentrations in a test group of three additional patients, to demonstrate its practical capabilities. The model is licensed on a free and permissive 2-Clause BSD license and is available to all clinicians; it can be accessed as a web application, available at https://csk.umed.pl/clotop.

Concentration-QTcF analysis of quizartinib in patients with newly diagnosed FLT3-internal-tandem-duplication-positive acute myeloid leukemia.

Quizartinib prolongs QT interval through inhibition of the slow delayed rectifier potassium current (IKs). We used non-linear mixed-effects modeling to explore the relationship between quizartinib and its pharmacologically active metabolite AC886 and the Fridericia-corrected QT interval (QTcF) in newly diagnosed acute myeloid leukemia (AML) patients. We evaluated linear and non-linear drug effect models, using triplicate QTcF measurements with available time-matched pharmacokinetic samples from the Phase 3 QuANTUM-First trial. The effect of intrinsic and extrinsic factors on model parameters was tested using stepwise covariate model building. Simulations were conducted to predict the change from baseline in QTcF (ΔQTcF) at the maximum concentration at steady-state (Cmax,ss) for quizartinib maintenance daily doses of 30 and 60 mg. The concentration-QTcF (C-QTcF) relationship was best described by a sigmoidal maximum effect model. After accounting for the effect of quizartinib, including AC886 concentrations did not further explain changes in QTcF. Circadian variations in QTcF were described using an empirical change from baseline based on clock times. Age and hypokalaemia were identified as statistically significant covariates on baseline QTcF; no covariates were found to impact the C-QTcF relationship. The median model-predicted ΔQTcF at Cmax,ss was 18.4 ms (90% confidence interval (CI): 16.3-20.5) at 30 mg and 24.1 ms (90% CI: 21.4-26.6) at 60 mg. In conclusion, in newly diagnosed AML patients, ΔQTcF increased non-linearly with increasing quizartinib concentrations. The predicted ΔQTcF increase at Cmax,ss supports the proposed dose adaptation based on observed QTcF and the dose reduction in case of strong cytochrome P450 3A (CYP3A) inhibitors coadministration.

Coadministration of Cariprazine with a Moderate CYP3A4 Inhibitor in Patients with Schizophrenia: Implications for Dose Adjustment and Safety Monitoring.

Cariprazine is metabolised mainly by CYP3A4 and to a lesser extent by CYP2D6. This study aimed to evaluate the effects of erythromycin, a moderate cytochrome P450 (CYP)3A4 inhibitor, on the pharmacokinetics of cariprazine in male patients with schizophrenia, and to assess the influence of CYP2D6 phenotypes on cariprazine metabolism. Forty-two patients received oral doses of 1.5 mg cariprazine alone for 28 days (to reach steady state), followed by a co-administration of cariprazine 1.5 mg daily with erythromycin 500 mg twice daily (BID) and Enterol 250 mg BID for 21 days, followed by a 14-day post-treatment period. Blood samples were collected at predefined time points and analysed for cariprazine, its two active metabolites: desmethyl cariprazine (DCAR) and didesmethyl cariprazine (DDCAR), and erythromycin using validated high performance liquid chromatography-tandem mass spectrometry methods. CYP2D6 phenotypes were determined by genotyping. The pharmacokinetic parameters were calculated using non-compartmental analysis. Erythromycin increased the area under the curve (AUCτ) and peak concentration (Cmax) of Total cariprazine (cariprazine + DCAR + DDCAR) by about 40-50% but did not affect the time to peak concentration (Tmax). The CYP2D6 phenotypes had no substantial effect on the pharmacokinetics of cariprazine and its metabolites, either alone or in combination with erythromycin. Cariprazine was well tolerated and safe. The findings suggest that co-administration of cariprazine with moderate CYP3A4 inhibitors may require dose adjustment or monitoring; however, pharmacogenetic testing for CYP2D6 is not necessary for optimising cariprazine therapy. Trial registration number (EudraCT Number): 2018-003721-28. Date of registration: 21-SEP-2018.

Disproportionality analysis of amenamevir-induced encephalopathy using the Japanese adverse drug event report database

IntroductionAnti-herpesvirus drug-induced encephalopathy can complicate herpes zoster treatment; however, the association between the recently developed anti-herpesvirus drug amenamevir and encephalopathy development remains unknown. Determining the characteristics of amenamevir-induced encephalopathy is essential for potentially improving patient outcomes in the treatment of herpes zoster. The aim of this study is to identify the association between amenamevir treatment and encephalopathy and to determine the risk factors for amenamevir-induced encephalopathy via disproportionality analysis using the Japanese Adverse Drug Event Report (JADER) database. MethodWe conducted a retrospective observational study using anonymized data from the JADER database. Encephalopathy was defined according to the Standardized Medical Dictionary for Regulatory Activities Queries specific to “Noninfectious encephalopathy/delirium.” Disproportionality analysis was used to calculate the reporting odds ratios (RORs) and 95 % confidence intervals (CIs) to assess associations between amenamevir and encephalopathy. Multivariable logistic regression considered age, gender, chronic kidney disease, and cytochrome P450 3A inhibitor use as potential risk factors. ResultsOut of 713,316 patients, 246 were prescribed amenamevir. The median onset of encephalopathy in these patients was 3 days. Disproportionality of encephalopathy was observed in patients treated with amenamevir (ROR, 3.44; 95 % CI, 2.48–4.78). Furthermore, multivariable logistic regression analysis suggested that an age of ≥70 years was associated with amenamevir-induced encephalopathy (ROR, 7.63; 95 % CI, 2.25–25.9). ConclusionThese results suggest that amenamevir treatment may be associated with encephalopathy, particularly in patients aged ≥70 years. Healthcare providers should be aware of this potential risk, especially in elderly patients, to prevent severe central nervous system complications.

Effect of Itraconazole, a CYP3A4 Inhibitor, and Rifampin, a CYP3A4 Inducer, on the Pharmacokinetics of Vatiquinone.

Vatiquinone is a small molecule inhibitor of 15-lipoxygenase in development for patients with Friedreich's ataxia. The objective of this analysis was to determine the effect of a cytochrome P450 isoform 3A4 (CYP3A4) inhibitor and inducer on vatiquinone pharmacokinetics (PKs). The coadministration of 400mg of vatiquinone with 200mg of itraconazole (a CYP3A4 inhibitor) resulted in increased maximum observed concentration (Cmax) of vatiquinone and systemic exposure (AUC0-inf) by approximately 3.5- and 2.9-fold, respectively. The coadministration of 400mg of vatiquinone with 600mg of rifampin (a CYP3A4 inducer) resulted in decreased vatiquinone Cmax and AUC0-inf by approximately 0.64- and 0.54-fold, respectively. The terminal half-life of vatiquinone was not affected by itraconazole or rifampin. These clinical study results confirm the in vitro reaction phenotyping data that shows that CYP3A4 plays an important role in vatiquinone metabolism. The result of this analysis together with phase 3 efficacy and safety data, population PK analysis, and the exposure-response relationship will determine if the extent of vatiquinone changes in the presence of CYP3A4 inhibitors and inducers are considered clinically relevant.

Apixaban plasma concentrations before and after catheter ablation for atrial fibrillation.

Catheter ablation in patients with atrial fibrillation is associated with a transient increase in thromboembolic risk and adequate anticoagulation is highly important. When patients are anticoagulated with apixaban, monitoring of plasma concentrations of the drug is not routinely performed. This study aimed to assess the influence of clinical patient characteristics, concomitant drug treatment and self-reported adherence on apixaban concentrations, and to describe the intra- and inter-individual variability in apixaban concentrations in this group of patients. Method Apixaban concentrations from 141 patients were measured in plasma one week before ablation and two, six and ten weeks after ablation, employing ultra-high performance liquid chromatography coupled with tandem mass spectrometry. In samples not obtained at trough, apixaban concentrations were adjusted to trough levels. Self-reported adherence was registered by means of the 8-item Morisky Medication Adherence Scale before and after ablation. There were statistically significant, positive correlations between apixaban concentrations and increased age, female sex, lower glomerular filtration rate, higher CHA2DS2-VASc score, use of cytochrome P450 3A4 and/or p-glycoprotein inhibitors, and use of amiodarone. Self-reported adherence was generally high. The mean intra-individual and inter-individual coefficients of variation were 29% and 49%, respectively. In patients undergoing catheter ablation for atrial fibrillation, age, sex, renal function, interacting drugs and cerebrovascular risk profile were all associated with altered plasma apixaban concentration. In this group of patients with a generally high self-reported adherence, intra-individual variability was modest, but the inter-individual variability was substantial, and similar to those previously reported in other patient apixaban-treated populations. If a therapeutic concentration range is established, there might be a need for a more flexible approach to apixaban dosing, guided by therapeutic drug monitoring.

Identification of reversible OATP1B1 and time-dependent CYP3A4 inhibition as the major risk factors for drug-induced cholestasis (DIC).

Hepatic bile acid regulation is a multifaceted process modulated by several hepatic transporters and enzymes. Drug-induced cholestasis (DIC), a main type of drug-induced liver injury (DILI), denotes any drug-mediated condition in which hepatic bile flow is impaired. Our ability in translating preclinical toxicological findings to human DIC risk is currently very limited, mainly due to important interspecies differences. Accordingly, the anticipation of clinical DIC with available in vitro or in silico models is also challenging, due to the complexity of the bile acid homeostasis. Herein, we assessed the in vitro inhibition potential of 47 marketed drugs with various degrees of reported DILI severity towards all metabolic and transport mechanisms currently known to be involved in the hepatic regulation of bile acids. The reported DILI concern and/or cholestatic annotation correlated with the number of investigated processes being inhibited. Furthermore, we employed univariate and multivariate statistical methods to determine the important processes for DILI discrimination. We identified time-dependent inhibition (TDI) of cytochrome P450 (CYP) 3A4 and reversible inhibition of the organic anion transporting polypeptide (OATP) 1B1 as the major risk factors for DIC among the tested mechanisms related to bile acid transport and metabolism. These results were consistent across multiple statistical methods and DILI classification systems applied in our dataset. We anticipate that our assessment of the two most important processes in the development of cholestasis will enable a risk assessment for DIC to be efficiently integrated into the preclinical development process.

A systematic review of the drug-drug interaction between Statins and Quinolones

BackgroundStatins are widely used in cardiovascular disease (CVD) as a common lipid-lowering drug, while quinolones are widely used for the treatment of infectious diseases. It is common to see CVD in combination with infectious diseases, therefore it is often the case that statins and quinolones are used in combination. Data suggest combinations of statin and quinolone may be associated with potentially life-threatening myopathy, rhabdomyolysis and acute hepatitis. This systematic review aims to characterize data regarding patients affected by the statin-quinolone interaction.MethodsThe purpose of this systematic review was to collect and evaluate the evidence surrounding statin-quinolone drug interactions and to discuss related risk mitigation strategies. The following databases were searched: PubMed (Medline), Embase, Scopus, and Cochrane Library. The systematic electronic literature search was conducted with the following search terms. In this study, three types of search terms were used: statins-related terms, quinolones-related terms, and drug interactions-related terms.ResultsThere were 16 case reports that met the criteria for qualitative analysis. Patients were involved in the following adverse reactions: rhabdomyolysis (n = 12), acute hepatitis (n = 1), muscle weakness (n = 1), hip tendinopathy (n = 1), or myopathy (n = 1). In the included literature, patients vary in the dose and type of statins they take, including simvastatin (n = 10) at a dose range of 20–80 mg/d and atorvastatin (n = 4) at a dose of 80 mg/d. There were 2 patients with unspecified statin doses, separately using simvastatin and atorvastatin. The quinolones in combination were ciprofloxacin (n = 9) at a dose range of 800–1500 mg/d, levofloxacin (n = 6) at a dose range of 250–1000 mg/d, and norfloxacin (n = 1) in an unspecified dose range. 81% of the case patients were over 60 years of age, and about 1/3 had kidney-related diseases such as diabetic nephropathy, post-transplantation, and severe glomerulonephritis. Nearly two-third of the patients were on concomitant cytochrome P450 3A4 (CYP3A4) inhibitors, P-glycoprotein (P-gp) inhibitors, or organic anion transporting polypeptide 1B1 (OATP1B1) inhibitors.ConclusionPatients treated with statin-quinolone combination should be monitored more closely for changes in aspartate aminotransferase or creatine kinase (CK) levels, and muscle symptoms, especially in patients with ciprofloxacin or levofloxacin, with simvastatin and high-dose atorvastatin, over 60 years of age, with kidney-related diseases, and on concomitant CYP3A4 inhibitors.

An Unusual Case Report of Iatrogenic Metrorrhagia and Hematochezia Following Itraconazole

Abstract Itraconazole is an effective triazole antimycotic drug that has a desirable pharmacokinetic profile to combat various fungal pathogens. It acts by inhibiting ergosterol biosynthesis in fungal cell membranes. Itraconazole is not totally selective toward Cytochrome P450 family 3 subfamily A member 4 (CYP450 3A4), but exhibits the most potent inhibition of CYP450 3A4. Thus, these drugs interfere with CYP450 3A4 proteins expressed in the liver, intestine, kidney, adrenals, ovary, and testis. We present a case report of metrorrhagia and hematochezia following intake of itraconazole, a commonly used azole drug against dermatophytic infection. This article strongly highlights eliciting menstrual history and gynecological- and surgical-related problems before prescribing itraconazole. Also, to be aware of the vaginal bleeding being the unusual side effects of itraconazole.

Prediction of the binding mechanism of a selective DNA methyltransferase 3A inhibitor by molecular simulation

DNA methylation is an epigenetic mechanism that introduces a methyl group at the C5 position of cytosine. This reaction is catalyzed by DNA methyltransferases (DNMTs) and is essential for the regulation of gene transcription. The DNMT1 and DNMT3A or -3B family proteins are known targets for the inhibition of DNA hypermethylation in cancer cells. A selective non-nucleoside DNMT3A inhibitor was developed that mimics S-adenosyl-l-methionine and deoxycytidine; however, the mechanism of selectivity is unclear because the inhibitor–protein complex structure determination is absent. Therefore, we performed docking and molecular dynamics simulations to predict the structure of the complex formed by the association between DNMT3A and the selective inhibitor. Our simulations, binding free energy decomposition analysis, structural isoform comparison, and residue scanning showed that Arg688 of DNMT3A is involved in the interaction with this inhibitor, as evidenced by its significant contribution to the binding free energy. The presence of Asn1192 at the corresponding residues in DNMT1 results in a loss of affinity for the inhibitor, suggesting that the interactions mediated by Arg688 in DNMT3A are essential for selectivity. Our findings can be applied in the design of DNMT-selective inhibitors and methylation-specific drug optimization procedures.

Iminium ion metabolites are formed from nintedanib by human CYP3A4

Nintedanib is used to treat idiopathic pulmonary fibrosis, systemic sclerosis, interstitial lung disease, and progressive fibrotic interstitial lung disease. It is primarily cleared via hepatic metabolism, hydrolysis, and glucuronidation. In addition, formation of the iminium ion, a possible reactive metabolite, was predicted based on the chemical structure of nintedanib. To obtain a hint which may help to clarify the cause of nintedanib-induced liver injury, we investigated whether iminium ions were formed in the human liver. To detect unstable iminium ions using liquid chromatography-tandem mass spectrometry (LC-MS/MS), potassium cyanide was added to the reaction mixture as a trapping agent. Human liver and intestinal microsomes were incubated with nintedanib in the presence of NADPH to form two iminium ion metabolites on the piperazine ring. Their formation is strongly inhibited by ketoconazole, a potent cytochrome P450 (CYP) 3A4 inhibitor. Among the recombinant P450s, only CYP3A4 formed cyanide adducts. The role of CYP3A4 was supported by the positive correlation between CYP3A4 protein abundance, as determined by LC-MS-based proteomics, and the formation of cyanide adducts in 25 individual human liver microsomes. In conclusion, we have demonstrated that iminium ion metabolites are formed from nintedanib by CYP3A4 as potential reactive metabolites.

Nirmatrelvir/ritonavir treatment of patients with COVID-19 taking tacrolimus: case series describing the results of drug-drug interactions.

Nirmatrelvir/ritonavir is a novel drug combination that is authorized by the Food and Drug Administration for the treatment of coronavirus disease 2019 (COVID-19). Ritonavir is a cytochrome P450 3A inhibitor and a P-glycoprotein inhibitor that increases the plasma concentration of tacrolimus and other medications. We describe the cases of two patients treated with nirmatrelvir/ritonavir: a patient who had undergone kidney transplantation and another with a history of hematopoietic stem cell transplantation. Toxic concentrations of tacrolimus were induced in both. This case series highlights the risk associated with the concomitant administration of tacrolimus and nirmatrelvir/ritonavir.

A Review of the Association between Infections, Seizures, and Drugs.

Seizures are a common presenting symptom of the central nervous system (CNS) and could occur from infections (such as toxins) or drugs. The aim of this study was to present a systematic review of the association between infections, seizures, and drugs. Through February 18, 2024, according to the PRISMA guidelines and based on the PICO standard format, relevant, in-depth consequent guide approach and evidence-based options were selected associated with a knowledgeable collection of current, high-quality manuscripts. Imbalance between inhibitory and excitatory neurotransmitters due to infections, drugs such as ticarcillin, amoxicillin, oxacillin, penicillin G, ampicillin, tramadol, venlafaxine, cyclosporine, tacrolimus, acyclovir, cellcept, the old generation of antiepileptic drugs, such as carbamazepine, phenytoin, and many other drugs could cause different stages of CNS disturbances ranging from seizure to encephalopathy. Infections could cause life-threatening status epilepticus by continuous unremitting seizures lasting longer than 5 minutes or recurrent seizures. Meningitis, tuberculosis, herpes simplex, cerebral toxoplasmosis, and many others could lead to status epilepticus. In fact, confusion, encephalopathy, and myoclonus were reported with drugs, such as ticarcillin, amoxicillin, oxacillin, penicillin G, ampicillin, and others. Penicillin G was reported as having the greatest epileptogenic potential. A high dose, in addition to prolonged use of metronidazole, was reported with seizure infection. Meropenem could decrease the concentration of valproic acid. Due to the inhibition of cytochrome P450 3A4, the combination of clarithromycin and erythromycin with carbamazepine needs vigilant monitoring. Due to changes in drug metabolism, co-administration of antiseizure drugs and antibiotics may lead to an enhanced risk of seizures. In patients with neurocysticercosis, cerebral malaria, viral encephalitis, bacterial meningitis, tuberculosis, and human immunodeficiency virus, the evidence-based study recommended different mechanisms mediating epileptogenic properties of toxins and drugs.

Proof-of-concept studies with a computationally designed Mpro inhibitor as a synergistic combination regimen alternative to Paxlovid

As the SARS-CoV-2 virus continues to spread and mutate, it remains important to focus not only on preventing spread through vaccination but also on treating infection with direct-acting antivirals (DAA). The approval of Paxlovid, a SARS-CoV-2 main protease (Mpro) DAA, has been significant for treatment of patients. A limitation of this DAA, however, is that the antiviral component, nirmatrelvir, is rapidly metabolized and requires inclusion of a CYP450 3A4 metabolic inhibitor, ritonavir, to boost levels of the active drug. Serious drug-drug interactions can occur with Paxlovid for patients who are also taking other medications metabolized by CYP4503A4, particularly transplant or otherwise immunocompromised patients who are most at risk for SARS-CoV-2 infection and the development of severe symptoms. Developing an alternative antiviral with improved pharmacological properties is critical for treatment of these patients. By using a computational and structure-guided approach, we were able to optimize a 100 to 250 μM screening hit to a potent nanomolar inhibitor and lead compound, Mpro61. In this study, we further evaluate Mpro61 as a lead compound, starting with examination of its mode of binding to SARS-CoV-2 Mpro. In vitro pharmacological profiling established a lack of off-target effects, particularly CYP450 3A4 inhibition, as well as potential for synergy with the currently approved alternate antiviral, molnupiravir. Development and subsequent testing of a capsule formulation for oral dosing of Mpro61 in B6-K18-hACE2 mice demonstrated favorable pharmacological properties, efficacy, and synergy with molnupiravir, and complete recovery from subsequent challenge by SARS-CoV-2, establishing Mpro61 as a promising potential preclinical candidate.

Structural Investigations of Phthalazinone Derivatives as Allosteric Inhibitors of Human DNA Methyltransferase 3A.

The development of new therapeutics targeting enzymes involved in epigenetic pathways such as histone modification and DNA methylation has received a lot of attention, particularly for targeting diverse cancers. Unfortunately, irreversible nucleoside inhibitors (azacytidine and decitabine) have proven highly cytotoxic, and competitive inhibitors are also problematic. This work describes synthetic and structural investigations of a new class of allosteric DNA methyltransferase 3A (DNMT3A) inhibitors, leading to the identification of several critical pharmacophores in the lead structure. Specifically, we find that the tetrazole and phthalazinone moieties are indispensable for the inhibitory activity of DNMT3A and elucidate other modifiable regions in the lead compound.

Clinical assessment of momelotinib drug-drug interactions via CYP3A metabolism and transporters.

Momelotinib-approved for treatment of myelofibrosis in adults with anemia-and its major active metabolite, M21, were assessed as drug-drug interaction (DDI) victims with a strong cytochrome P450 (CYP) 3A4 inhibitor (multiple-dose ritonavir), an organic anion transporting polypeptide (OATP) 1B1/1B3 inhibitor (single-dose rifampin), and a strong CYP3A4 inducer (multiple-dose rifampin). Momelotinib DDI perpetrator potential (multiple-dose) was evaluated with CYP3A4 and breast cancer resistance protein (BCRP) substrates (midazolam and rosuvastatin, respectively). DDI was assessed from changes in maximum plasma concentration (Cmax), area under the concentration-time curve (AUC), time to reach Cmax, and half-life. The increase in momelotinib (23% Cmax, 14% AUC) or M21 (30% Cmax, 24% AUC) exposure with ritonavir coadministration was not clinically relevant. A moderate increase in momelotinib (40% Cmax, 57% AUC) and minimal change in M21 was observed with single-dose rifampin. A moderate decrease in momelotinib (29% Cmax, 46% AUC) and increase in M21 (31% Cmax, 15% AUC) were observed with multiple-dose rifampin compared with single-dose rifampin. Due to potentially counteracting effects of OATP1B1/1B3 inhibition and CYP3A4 induction, multiple-dose rifampin did not significantly change momelotinib pharmacokinetics compared with momelotinib alone (Cmax no change, 15% AUC decrease). Momelotinib did not alter the pharmacokinetics of midazolam (8% Cmax, 16% AUC decreases) or 1'-hydroxymidazolam (14% Cmax, 16% AUC decreases) but increased rosuvastatin Cmax by 220% and AUC by 170%. Safety findings were mild in this short-term study in healthy volunteers. This analysis suggests that momelotinib interactions with OATP1B1/1B3 inhibitors and BCRP substrates may warrant monitoring for adverse reactions or dose adjustments.

Clinical Pharmacology of the Antibody-Drug Conjugate Enfortumab Vedotin in Advanced Urothelial Carcinoma and Other Malignant Solid Tumors.

Enfortumab vedotin is an antibody-drug conjugate comprised of a human monoclonal antibody directed to Nectin-4 and monomethyl auristatin E (MMAE), a microtubule-disrupting agent. The objectives of this review are to summarize the clinical pharmacology of enfortumab vedotin monotherapy and demonstrate that the appropriate dose has been selected for clinical use. Pharmacokinetics (PK) of enfortumab vedotin (antibody-drug conjugate and total antibody) and free MMAE were evaluated in five clinical trials of patients with locally advanced or metastatic urothelial carcinoma (n=748). Intravenous enfortumab vedotin 0.5-1.25 mg/kg on days 1, 8, and 15 of a 28-day cycle showed linear, dose-proportional PK. No significant differences in exposure or safety of enfortumab vedotin and free MMAE were observed in mild, moderate, or severe renal impairment versus normal renal function. Patients with mildly impaired versus normal hepatic function had a 37% increase in area under the concentration-time curve (0-28 days), a 31% increase in maximum concentration of free MMAE, and a similar adverse event profile. No clinically significant PK differences were observed based on race/ethnicity with weight-based dosing, and no clinically meaningful QT prolongation was observed. Concomitant use with dual P-glycoprotein and strong cytochrome P450 3A4 inhibitors may increase MMAE exposure and the risk of adverse events. Approximately 3% of patients developed antitherapeutic antibodies against enfortumab vedotin 1.25 mg/kg. These findings support enfortumab vedotin 1.25 mg/kg monotherapy on days 1, 8, and 15 of a 28-day cycle. No dose adjustments are required for patients with renal impairment or mild hepatic impairment, or by race/ethnicity.

Evaluation of machine learning models for cytochrome P450 3A4, 2D6, and 2C9 inhibition.

Cytochrome P450 (CYP) enzymes are involved in the metabolism of approximately 75% of marketed drugs. Inhibition of the major drug-metabolizing P450s could alter drug metabolism and lead to undesirable drug-drug interactions. Therefore, it is of great significance to explore the inhibition of P450s in drug discovery. Currently, machine learning including deep learning algorithms has been widely used for constructing in silico models for the prediction of P450 inhibition. These models exhibited varying predictive performance depending on the use of machine learning algorithms and molecular representations. This leads to the difficulty in the selection of appropriate models for practical use. In this study, we systematically evaluated the conventional machine learning and deep learning models for three major P450 enzymes, CYP3A4, CYP2D6, and CYP2C9 from several perspectives, such as algorithms, molecular representation, and data partitioning strategies. Our results showed that the XGBoost and CatBoost algorithms coupled with the combined fingerprint/physicochemical descriptor features exhibited the best performance with Area Under Curve (AUC) of 0.92, while the deep learning models were generally inferior to the conventional machine learning models (average AUC reached 0.89) on the same test sets. We also found that data volume and sampling strategy had a minor effect on model performance. We anticipate that these results are helpful for the selection of molecular representations and machine learning/deep learning algorithms in the P450 model construction and the future model development of P450 inhibition.

A global phase II randomized trial comparing oral taxane ModraDoc006/r to intravenous docetaxel in metastatic castration resistant prostate cancer

Study aimModraDoc006, an oral formulation of docetaxel, is co-administered with the cytochrome P450–3A4 and P-glycoprotein inhibitor, ritonavir (r): ModraDoc006/r. The preliminary efficacy and safety of oral ModraDoc006/r was evaluated in a global randomized phase II trial and compared to the current standard chemotherapy regimen of intravenous (i.v.) docetaxel and prednisone. Methods103 mCRPC patients, chemotherapy-naïve with/without abiraterone and/or enzalutamide pretreated, with adequate organ function and evaluable disease per RECIST v1.1 and PCWG3 guidelines were randomized 1:1 into two cohorts. In Cohort 1, 49 patients received docetaxel 75 mg/m2 i.v. every 3 weeks (Q3W). In Cohort 2, 52 patients received ModraDoc006/r; 21 patients with a starting dose of ModraDoc006 30 mg with ritonavir 200 mg in the morning and ModraDoc006 20 mg with ritonavir 100 mg in the evening (30–20/200–100 mg) bi-daily-once-weekly (BIDW) on Days 1, 8, and 15 of a 21-day cycle. To alleviate tolerability, the starting dose was amended to ModraDoc006/r 20–20/200–100 mg in another 31 patients. All patients received prednisone 10 mg daily. Primary endpoint was rPFS. ResultsThere was no significant difference in rPFS between the 2 arms (p = 0.1465). Median rPFS was 9.5 months and 11.1 months (95% CI) for ModraDoc006/r and i.v. docetaxel, respectively. Partial response was noted in 44.1% and 38.7% measurable disease patients, and 50% decline of PSA was seen in 23 (50%) and 26 (56.5%) evaluable cases treated with ModraDoc006/r and i.v. docetaxel, respectively. The safety profile of ModraDoc006/r 20–20/200–100 mg dose was significantly better than i.v. docetaxel, with mild (mostly Grade 1) gastrointestinal toxicities, no hematologic adverse events, and neuropathy and alopecia incidence of 11.5% and 25%, respectively. ConclusionsModraDoc006/r potentially represents a widely applicable, convenient, effective, and better tolerated oral taxane therapy option for mCRPC. Further investigation of ModraDoc006/r in a large randomized trial is warranted.

Impact of loperamide on the pharmacokinetics and tissue disposition of ritonavir-boosted oral docetaxel therapy; a preclinical assessment.

An oral docetaxel formulation boosted by the Cytochrome P450 (CYP) 3A inhibitor ritonavir, ModraDoc006/r, is currently under clinical investigation. Based on clinical data, the incidence of grade 1-2 diarrhea is increased with this oral docetaxel formulation compared to the conventional intravenous administration. Loperamide, a frequently used diarrhea inhibitor, could be added to the regimen as symptomatic treatment. However, loperamide is also a substrate of the CYP3A enzyme, which could result in competition between ritonavir and loperamide for this protein. Therefore, we were interested in the impact of coadministered loperamide on the pharmacokinetics of ritonavir-boosted oral docetaxel. We administered loperamide simultaneously or with an 8-hour delay to humanized CYP3A4 mice (with expression in liver and intestine) receiving oral ritonavir and docetaxel. Concentrations of docetaxel, ritonavir, loperamide and two of its active metabolites were measured. The plasma exposure (AUC and Cmax) of docetaxel was not altered during loperamide treatment, nor were the ritonavir plasma pharmacokinetics. However, the hepatic and intestinal dispositions of ritonavir were somewhat changed in the simultaneous, but not 8-hour loperamide treatment groups, possibly due to loperamide-induced delayed drug absorption. The pharmacokinetics of loperamide itself did not seem to be influenced by ritonavir. These results suggest that delayed loperamide administration can be added to ritonavir-boosted oral docetaxel treatment, without affecting the overall systemic exposure of docetaxel.