Effect of tyrosine kinase inhibitors on renal handling of creatinine by MATE1

Practical considerations in the management of patients treated with bosutinib for chronic myeloid leukemia

Bosutinib is a second-generation tyrosine kinase inhibitor indicated for the treatment of patients with newly diagnosed Philadelphia chromosome-positive chronic phase chronic myeloid leukemia (CML), and for patients with Ph + chronic phase, accelerated phase, or blast phase CML resistant or intolerant to prior therapy. As is the case for all TKIs approved for treatment of CML, bosutinib is associated with adverse events (AEs) that require appropriate management to ensure adherence to treatment and optimized outcomes. The aim of this review is to provide physicians with updated practical information for the prevention and management of AEs occurring during treatment with bosutinib, including dosing strategies, based on the latest published evidence and clinical experience. Clinical studies and real-world evidence have shown bosutinib has a generally favorable safety profile, which has remained consistent across lines of therapy and in long-term reports. Adjusting the starting dose and/or modifying the dose during treatment with bosutinib are important strategies to manage AEs and improve tolerability, which are recognized within the label and in treatment guidelines. Dosing adjustment strategies to manage AEs are a recognized management approach for other TKIs in the treatment of CML and are not exclusive to bosutinib. In summary, long-term results from clinical trials and emerging real-world evidence demonstrate bosutinib has a safety profile that can largely be managed with treatment modifications and/or supportive care. Increased experience in managing toxicities and by using a personalized dosing approach may further improve adherence and outcomes with bosutinib.

Pharmacology of Tyrosine Kinase Inhibitors: Implications for Patients with Kidney Diseases

Tyrosine kinase inhibitors (TKI) have introduced a significant advancement in cancer management. These compounds are administered orally, and their absorption holds a pivotal role in determining their variable efficacy. They exhibit extensive distribution within the body, binding strongly to both plasma and tissue proteins. Often reliant on efflux and influx transporters, TKI undergo primary metabolism by intestinal and hepatic cytochrome P450 enzymes, with nonkidney clearance being predominant. Owing to their limited therapeutic window, many TKI display considerable intraindividual and interindividual variability. This review offers a comprehensive analysis of the clinical pharmacokinetics of TKI, detailing their interactions with drug transporters and metabolic enzymes, while discussing potential clinical implications. The prevalence of kidney conditions, such as AKI and CKD, among patients with cancer is explored in their effect on TKI pharmacokinetics. Finally, the potential nephrotoxicity associated with TKI is also examined.

Efficacy and safety of tepotinib in Asian patients with advanced NSCLC with MET exon 14 skipping enrolled in VISION

BACKGROUND

Tepotinib, a MET inhibitor approved for the treatment of MET exon 14 (METex14) skipping NSCLC, demonstrated durable clinical activity in VISION (Cohort A + C; N = 313): objective response rate (ORR) 51.4% (95% CI: 45.8, 57.1); median duration of response (mDOR) 18.0 months (95% CI: 12.4, 46.4). We report outcomes in Asian patients from VISION (Cohort A + C) (cut-off: November 20, 2022).

METHODS

Patients with advanced METex14 skipping NSCLC, detected by liquid or tissue biopsy, received tepotinib 500 mg (450 mg active moiety) once daily.

PRIMARY ENDPOINT

objective response (RECIST 1.1) by independent review. Secondary endpoints included: DOR, progression-free survival (PFS), overall survival (OS), safety, and health-related quality of life (HRQoL).

RESULTS

Across treatment lines in 106 Asian patients (39.6% female, 43.4% smoking history, 79.2% adenocarcinoma, 47.2% treatment-naive), ORR was 56.6% (95% CI: 46.6, 66.2), mDOR 18.5 months (10.4, ne), mPFS 13.8 months (10.8, 22.0), and mOS 25.5 months (19.3, 36.4). Consistent efficacy observed, regardless of baseline characteristics. HRQoL remained stable during treatment. Treatment-related adverse events (TRAEs) occurred in 95.3% of patients (39.6% Grade ≥3). Most common TRAEs: peripheral edema (62.3%), creatinine increase (38.7%).

CONCLUSIONS

Tepotinib demonstrated robust and durable efficacy, with a manageable safety profile, in Asian patients with METex14 skipping NSCLC.

CLINICAL TRIAL REGISTRATION

NCT02864992.

Long-term experience with tepotinib in Japanese patients with MET exon 14 skipping NSCLC from the Phase II VISION study

Tepotinib is a highly selective MET tyrosine kinase inhibitor (TKI) that has demonstrated robust and durable clinical activity in patients with MET exon 14 (METex14) skipping non-small-cell lung cancer (NSCLC). In the Phase II VISION study, patients received oral tepotinib 500 mg once daily. The primary endpoint was an objective response by an independent review committee (IRC) according to RECIST v1.1 criteria. The secondary endpoints included duration of response (DOR), progression-free survival (PFS), overall survival (OS), and safety. Here we report the analysis of the efficacy and safety of tepotinib in all Japanese patients with advanced METex14 skipping NSCLC from VISION (n = 38) with >18 months' follow-up. The median age of the Japanese patients was 73 years (range 63-88), 39.5% of patients were ≥75 years old, 68.4% were male, 55.3% had a history of smoking, 76.3% had adenocarcinoma, and 10.5% of patients had known brain metastases at baseline. Overall, the objective response rate (ORR) was 60.5% (95% confidence interval (CI): 43.4, 76.0) with a median DOR of 18.5 months (95% CI: 8.3, not estimable). ORR in treatment-naïve patients (n = 18) was 77.8% (95% CI: 52.4, 93.6), and in patients aged ≥75 years (n = 15), ORR was 73.3% (95% CI: 44.9, 92.2). The most common treatment-related adverse event (AE) with any grade was blood creatinine increase (65.8%), which resolved following tepotinib discontinuation. Other common treatment-related AEs were peripheral edema (60.5%), hypoalbuminemia (34.2%), diarrhea (28.9%), and nausea (15.8%). In summary, tepotinib demonstrated robust and durable clinical activity irrespective of age or therapy line, with a manageable safety profile in Japanese patients with METex14 skipping NSCLC enrolled in VISION.

Brief Report: Tyrosine Kinase Inhibitors for Lung Cancers That Inhibit MATE-1 Can Lead to "False" Decreases in Renal Function

INTRODUCTION

Select tyrosine kinase inhibitors (TKIs) used to treat oncogene-driven lung cancers also inhibit MATE-1. When MATE-1 is blocked, creatinine is retained in the serum. Elevated creatinine levels raise the specter of drug-induced intrarenal insufficiency despite the lack of true renal injury. We conducted a systematic analysis of MATE-1 inhibitor (MATEi)-treated patients to comprehensively characterize this phenomenon.

METHODS

Patients with oncogene-driven lung cancer treated with a wide variety of MATEi TKIs (brigatinib, cabozantinib, capmatinib, crizotinib, entrectinib, lorlatinib, pralsetinib, selpercatinib, and tepotinib) were eligible for an analysis of renal dysfunction. Acute kidney injury was classified on the basis of creatinine levels (Kidney Disease: Improving Global Outcomes criteria) as stage 1 (≥1.5× but <2× baseline), stage 2 (≥2× but <3× baseline), or stage 3 (>3× baseline). When available, cystatin C, a marker of kidney function unaffected by MATE-1, was used to evaluate the glomerular filtration rate (GFR).

RESULTS

We identified 863 patients receiving MATEi TKIs including crizotinib (39%, n = 333), lorlatinib (17%, n = 144), cabozantinib (10%, n = 87), selpercatinib (10%, n = 82), capmatinib (9%, n = 77), brigatinib (6%, n = 53), entrectinib (5%, n = 45), tepotinib (5%, n = 41), and pralsetinib (0.1%, n = 1). Of the 90 patients (10%) with acute kidney injury, Kidney Disease: Improving Global Outcomes stages 1, 2, and 3 were observed in 72% (n = 65), 21% (n = 19), and 7% (n = 6) of patients, respectively. Concurrently drawn creatinine and cystatin C levels on TKI therapy were available for 17 patients. In most cases (n = 15 of 17), the calculated GFR was higher using cystatin C versus creatinine. The percentage of patients whose GFR was higher using cystatin C versus creatinine by less than 10 mL/min, 10 to 19 mL/min, 20 to 29 mL/min, and more than or equal to 30 mL/min was 27% (n = four of 15), 20% (n = three of 15), 20% (n = three of 15), and 33% (n = five of 15), respectively. Long-term data in three patients that spanned 3 years revealed that GFR was higher using cystatin C versus creatinine in 96% (n = 49 of 51) of all time points. Using a virtual clinical trial GFR cutoff of 40 mL/min, the percentage of eligible patients rose from 41% (n = seven of 17) using creatinine calculations to 71% (n = 12 of 17) using cystatin C calculations.

CONCLUSIONS

The calculated GFR in patients with cancer receiving MATEi TKIs was higher in almost all cases when using cystatin C. When serum creatinine level seems elevated in patients receiving MATE-1 inhibitors, we recommend recalculating GFR using cystatin C before searching for other etiologies of kidney injury and reducing or stopping TKI therapy.

Quantitative Consideration of Clinical Increases in Serum Creatinine Caused by Renal Transporter Inhibition

Creatinine is a common biomarker of renal function and is secreted in the renal tubular cells via drug transporters, such as organic cation transporter 2 and multidrug and toxin extrusion (MATE) 1/2-K. To differentiate between drug-induced acute kidney injury (AKI) and drug interactions through the renal transporter, it has been examined whether these transporter inhibitions quantitatively explained increases in serum creatinine (SCr) at their clinically relevant concentrations using drugs without any changes in renal function. For such renal transporter inhibitors and recently approved tyrosine kinase inhibitors (TKIs), this mini-review describes clinical increases in SCr and inhibitory potentials against the renal transporters. Most cases of SCr elevations can be explained by considering the renal transporter inhibitions based on unbound maximum plasma concentrations, except for drugs associated with obvious changes in renal function. SCr increases for cobicistat, dolutegravir, and dronedarone, and some TKIs were significantly underestimated, and these underestimations were suggested to be associated with low plasma unbound fractions. Sensitivity analysis of SCr elevations regarding inhibitory potentials of MATE1/2-K demonstrated that typical inhibitors such as cimetidine, DX-619, pyrimethamine, and trimethoprim could give false interpretations of AKI according to the criteria based on relative or absolute levels of SCr elevations. Recent progress and current challenges of physiologically-based pharmacokinetics modeling for creatinine disposition were also summarized. Although it should be noted for the potential impact of in vitro assay designs on clinical translatability of transporter inhibitions data, mechanistic approaches could support decision-making in clinical development to differentiate between AKI and creatinine-drug interactions. SIGNIFICANCE STATEMENT: Serum creatinine (SCr) is widely used as an indicator of kidney function, but it increases due to inhibitions of renal transporters, such as multidrug and toxin extrusion protein 1/2-K despite no functional changes in the kidney. Such SCr elevations were quantitatively explained by renal transporter inhibitions except for some drugs with high protein binding. The present analysis demonstrated that clinically relevant inhibitors of the renal transporters could cause SCr elevations above levels corresponding to acute kidney injury criteria.

Preincubation Time-Dependent, Long-Lasting Inhibition of Drug Transporters and Impact on the Prediction of Drug-Drug Interactions

Transporter-mediated drug-drug interaction (DDI) is of clinical concern, and the quantitative prediction of DDIs is an indispensable part of drug development. Cell-based inhibition assays, in which a representative probe substrate and a potential inhibitor are coincubated, are routinely performed to assess the inhibitory potential of new molecular entities on drug transporters. However, the inhibitory effect of cyclosporine A (CsA) on organic anion transporting polypeptide (OATP) 1B1 is substantially potentiated with CsA preincubation, and this effect is both long-lasting and dependent on the preincubation time. This phenomenon has also been reported with transporters other than OATP1Bs, but it is considered more prevalent among OATP1Bs and organic cation transporters. Regulatory agencies have also noted this preincubation effect and have recommended that pharmaceutical companies consider inhibitor preincubation when performing in vitro OATP1B1 and OATP1B3 inhibition studies. Although the underlying mechanisms responsible for the preincubation effect are not fully understood, a trans-inhibition mechanism was recently demonstrated for OATP1B1 inhibition by CsA, in which CsA inhibited OATP1B1 not only extracellularly (cis-inhibition) but also intracellularly (trans-inhibition). Furthermore, the trans-inhibition potency of CsA was much greater than that of cis-inhibition, suggesting that trans-inhibition might be a key driver of clinical DDIs of CsA with OATP1B substrate drugs. Although confidence in transporter-mediated DDI prediction is generally considered to be low, the predictability might be further improved by incorporating the trans-inhibition mechanism into static and dynamic models for preincubation-dependent inhibitors of OATP1Bs and perhaps other transporters. SIGNIFICANCE STATEMENT: Preincubation time-dependent, long-lasting inhibition has been observed for OATP1B1 and other solute carrier transporters in vitro. Recently, a trans-inhibition mechanism for the preincubation effect of CsA on OATP1B1 inhibition was identified, with the trans-inhibition potency being greater than that of cis-inhibition. The concept of trans-inhibition may allow us to further understand the mechanism of transporter-mediated DDIs not only for OATP1B1 but also for other transporters and to improve the accuracy and confidence of DDI predictions.

Emerging Roles of Uremic Toxins and Inflammatory Cytokines in the Alteration of Hepatic Drug Disposition in Patients with Kidney Dysfunction

Patients with kidney dysfunction exhibit distinct pharmacokinetic profiles compared to those with normal kidney function. Hence, it is desirable to monitor the drug efficacy and toxicity caused by fluctuations in plasma drug concentrations associated with kidney dysfunction. Recently, pharmacokinetic information of drugs excreted mainly through the urine of patients with kidney dysfunction has been reported via drug-labeling information. Pharmacokinetic changes in drugs mainly eliminated by the liver cannot be overlooked as drug metabolism and/or transport activity in the liver may also be altered in patients with kidney dysfunction; however, the underlying mechanisms remain unclear. To plan an appropriate dosage regimen, it is necessary to clarify the underlying processes of functional changes in pharmacokinetic proteins. In recent years, uremic toxins have been shown to reduce the activity and/or expression of renal and hepatic transporters. This inhibitory effect has been reported to be time-dependent. In addition, inflammatory cytokines, such as interleukin-6, released from immune cells activated by uremic toxins and/or kidney injury can reduce the expression levels of drug-metabolizing enzymes and transporters in human hepatocytes. In this mini-review, we have summarized the renal and hepatic pharmacokinetic changes as well as the potential underlying mechanisms in kidney dysfunction, such as the chronic kidney disease and acute kidney injury. SIGNIFICANCE STATEMENT: Patients with kidney dysfunction exhibit distinct pharmacokinetic profiles compared to those with normal kidney function. Increased plasma concentrations of uremic toxins and inflammatory cytokines during kidney disease may potentially affect the activities and/or expression levels of drug-metabolizing enzymes and transporters in the liver and kidneys.

Clinical and metabolomic characterization of Brivanib-Induced hypertension in metastatic colorectal cancer

BACKGROUND

Trials of tyrosine kinase inhibitors (TKI) have not demonstrated dramatic benefits in advanced colorectal cancer (CRC), and this may be a function of poor patient selection. TKI-induced hypertension is reportedly a surrogate marker for treatment benefit for some tumor types. Our objective was to determine whether hypertension was associated with benefit in the context of CRC treatment, and also to gain insight on the pathogenesis of TKI-induced hypertension by monitoring associated changes in the circulating metabolome.

PATIENTS AND METHODS

Clinical data were acquired from clinical trial patients with metastatic CRC randomized to cetuximab ± the TKI brivanib (N = 750). Outcomes were evaluated as a function of treatment-induced hypertension. For metabolomic studies, plasma samples were taken at baseline, as well as at 1, 4, and 12 weeks after treatment initiation. Samples were submitted to gas chromatography-mass spectrometry to identify treatment-related metabolomic changes associated with TKI-induced hypertension, compared to pre-treatment baseline. A model based on changes in metabolite concentrations was generated using orthogonal partial least squares discriminant analysis (OPLS-DA).

RESULTS

In the brivanib treated group, 95 patients had treatment-related hypertension within 12 weeks of initiating treatment. TKI-induced hypertension was not associated with a significantly higher response rate, nor was it associated with improved progression-free or overall survival. In metabolomic studies, 386 metabolites were identified. There were 29 metabolites that changed with treatment and distinguished patients with and without TKI-induced hypertension. The OPLS-DA model for brivanib-induced hypertension was significant and robust (R2 Y score = 0.89, Q2 Y score = 0.70, CV-ANOVA = 2.01 e-7). Notable metabolomic features previously reported in pre-eclampsia and associated with vasoconstriction were found.

CONCLUSION

TKI-induced hypertension was not associated with clinical benefit in metastatic CRC. We have identified changes in the metabolome that are associated with the development of worsening brivanib-induced hypertension that may be useful in future efforts of characterizing this toxicity.

Time to Rethink the Current Paradigm for Assessing Kidney Function in Drug Development and Beyond

Chronic kidney disease (CKD) is an important health issue that affects ~ 9.1% of the world adult population. Serum creatinine is the most commonly used biomarker for assessing kidney function and is utilized in different equations for estimating creatinine clearance or glomerular filtration rate (GFR). The Cockcroft-Gault formula for adults and "original" Schwartz formula for children have been the most commonly used equations for estimating kidney function during the last 3-4 decades. Introduction of standardized serum creatinine bioanalytical methodology has reduced interlaboratory variability but is not intended to be used with Cockcroft-Gault or original Schwartz equations. More accurate equations (for instance, Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) for adults and bedside Schwartz or Chronic Kidney Disease in Children Schwartz equation for children) based on standardized serum creatinine values (and another biomarker-cystatin C) have been introduced and validated in recent years. Recently, the CKD-EPI equation refitted without a race variable was introduced. Clinical practice guidance in nephrology advocates a shift to these equations for managing health care of patients with CKD. The guidance also recommends use of albuminuria in addition to GFR for CKD diagnosis and management. Significant research with large data sets would be necessary to evaluate whether this paradigm would also be valuable in drug dose adjustments. This article attempts to highlight some important advancements in the field from a clinical pharmacology perspective and is a call to action to industry, regulators, and academia to rethink the current paradigm for assessing kidney function to enable dose recommendation in patients with CKD.

Chronic kidney disease and cognitive decline in patients with type 2 diabetes at elevated cardiovascular risk

AIMS

We addressed the question whether chronic kidney disease (CKD) may contribute to cognitive decline in type 2 diabetes.

METHODS

Participants with type 2 diabetes with elevated cardiovascular risk or CKD from cognition substudies of two large trials were studied prospectively (CARMELINA: n = 2666, mean ± SD age 68.1 ± 8.7 years, CAROLINA: n = 4296; 64.7 ± 9.4 years). Estimated glomerular filtration rate (eGFR) and urine albumin-to-creatinine ratio (UACR) at baseline were related to cognitive performance (Mini-Mental State Examination (MMSE) and attention and executive functioning score (A&E)) in linear regression analyses, adjusted for demographics, cardiovascular risk factors and treatment, at baseline and follow-up.

RESULTS

CKD at baseline was more common in CARMELINA than CAROLINA (eGFR<60 in 72.6 % and 19.6 %, macroalbuminuria in 35.0 % and 4.1 %, respectively). Baseline eGFR was related to A&E in CARMELINA (b = 0.02 per 10 ml/min/1.73m², 95%CI [0.01,0.03]). Baseline UACR was related to A&E in CAROLINA (b = -0.01 per doubling of UACR mg/g, 95%CI [-0.02,-0.002]). Baseline UACR predicted decline in A&E in CAROLINA (median 6.1 years follow-up; b = -0.01, 95%CI [-0.03,-0.0001] per doubling of UACR mg/g).

CONCLUSIONS

eGFR and UACR were associated with A&E in two cohorts with type 2 diabetes, enriched for CKD and cardiovascular disease. The small effect size estimates indicate limited impact of kidney dysfunction on cognition in this setting.

GOV IDENTIFIERS

NCT01897532 NCT01243424.

DCBLD2 regulates vascular hyperplasia by modulating the platelet derived growth factor receptor-β endocytosis through Caveolin-1 in vascular smooth muscle cells

DCBLD2 is a neuropilin-like transmembrane protein that is up-regulated during arterial remodeling in humans, rats, and mice. Activation of PDGFR-β via PDGF triggers receptor phosphorylation and endocytosis. Subsequent activation of downstream signals leads to the stimulation of phenotypic conversion of VSMCs and arterial wall proliferation, which are common pathological changes in vascular remodeling diseases such as atherosclerosis, hypertension, and restenosis after angioplasty. In this study, we hypothesized that DCBLD2 regulates neointimal hyperplasia through the regulation of PDGFR-β endocytosis of vascular smooth muscle cells (VSMCs) through Caveolin-1 (Cav-1). Compared with wild-type (WT) mice or control littermate mice, the germline or VSMC conditional deletion of the Dcbld2 gene resulted in a significant increase in the thickness of the tunica media in the carotid artery ligation. To elucidate the underlying molecular mechanisms, VSMCs were isolated from the aorta of WT or Dcbld2-/- mice and were stimulated with PDGF. Western blotting assays demonstrated that Dcbld2 deletion increased the PDGF signaling pathway. Biotin labeling test and membrane-cytosol separation test showed that after DCBLD2 was knocked down or knocked out, the level of PDGFR-β on the cell membrane was significantly reduced, while the amount of PDGFR-β in the cytoplasm increased. Co-immunoprecipitation experiments showed that after DCBLD2 gene knock-out, the binding of PDGFR-β and Cav-1 in the cytoplasm significantly increased. Double immunofluorescence staining showed that PDGFR-β accumulated Cav-1/lysosomes earlier than for control cells, which indicated that DCBLD2 gene knock-down or deletion accelerated the endocytosis of PDGF-induced PDGFR-β in VSMCs. In order to confirm that DCBLD2 affects the relationship between Cav-1 and PDGFR-β, proteins extracted from VSMCs cultured in vitro were derived from WT and Dcbld2-/- mice, whereas co-immunoprecipitation suggested that the combination of DCBLD2 and Cav-1 reduced the bond between Cav-1 and PDGFR-β, and DCBLD2 knock-out was able to enhance the interaction between Cav-1 and PDGFR-β. Therefore, the current results suggest that DCBLD2 may inhibit the caveolae-dependent endocytosis of PDGFR-β by anchoring the receptor on the cell membrane. Based on its ability to regulate the activity of PDGFR-β, DCBLD2 may be a novel therapeutic target for the treatment of cardiovascular diseases.

Advantages, Limitations, and Clinical Considerations in Using Cystatin C to Estimate GFR

Cystatin C has been shown to be a reliable and accurate marker of kidney function across diverse populations. The 2012 Kidney Disease Improving Global Outcomes (KDIGO) guidelines recommended using cystatin C to confirm the diagnosis of chronic kidney disease (CKD) determined by creatinine-based estimated glomerular filtration rate (eGFR) and to estimate kidney function when accurate eGFR estimates are needed for clinical decision-making. In the efforts to remove race from eGFR calculations in the United States, the National Kidney Foundation (NKF) and American Society of Nephrology (ASN) Joint Task Force recommended increasing availability and clinical adoption of cystatin C to assess kidney function. This review summarizes the key advantages and limitations of cystatin C use in clinical practice. Our goals were to review and discuss the literature on cystatin C; understand the evidence behind the recommendations for its use as a marker of kidney function to diagnose CKD and risk stratify patients for adverse outcomes; discuss the challenges of its use in clinical practice; and guide clinicians on its interpretation.

Role of Drug Transporters in Elucidating Inter-Individual Variability in Pediatric Chemotherapy-Related Toxicities and Response

Pediatric cancer treatment has evolved significantly in recent decades. The implementation of risk stratification strategies and the selection of evidence-based chemotherapy combinations have improved survival outcomes. However, there is large interindividual variability in terms of chemotherapy-related toxicities and, sometimes, the response among this population. This variability is partly attributed to the functional variability of drug-metabolizing enzymes (DME) and drug transporters (DTS) involved in the process of absorption, distribution, metabolism and excretion (ADME). The DTS, being ubiquitous, affects drug disposition across membranes and has relevance in determining chemotherapy response in pediatric cancer patients. Among the factors affecting DTS function, ontogeny or maturation is important in the pediatric population. In this narrative review, we describe the role of drug uptake/efflux transporters in defining pediatric chemotherapy-treatment-related toxicities and responses. Developmental differences in DTS and the consequent implications are also briefly discussed for the most commonly used chemotherapeutic drugs in the pediatric population.

Reimagining the Framework Supporting the Static Analysis of Transporter Drug Interaction Risk; Integrated Use of Biomarkers to Generate Pan‐Transporter Inhibition Signatures

Solute carrier (SLC) transporters present as the loci of important drug-drug interactions (DDIs). Therefore, sponsors generate in vitro half-maximal inhibitory concentration (IC₅₀ ) data and apply regulatory agency-guided "static" methods to assess DDI risk and the need for a formal clinical DDI study. Because such methods are conservative and high false-positive rates are likely (e.g., DDI study triggered when liver SLC R value ≥ 1.04 and renal SLC maximal unbound plasma (C_max,u )/IC₅₀ ratio ≥ 0.02), investigators have attempted to deploy plasma- and urine-based SLC biomarkers in phase I studies to de-risk DDI and obviate the need for drug probe-based studies. In this regard, it was possible to generate in-house in vitro SLC IC₅₀ data for various clinically (biomarker)-qualified perpetrator drugs, under standard assay conditions, and then estimate "% inhibition" for each SLC and relate it empirically to published clinical biomarker data (area under the plasma concentration vs. time curve (AUC) ratio (AUCR, AUC_inhibitor /AUC_reference ) and % decrease in renal clearance (ΔCL_renal )). After such a "calibration" exercise, it was determined that only compounds with high R values (> 1.5) and C_max,u /IC₅₀ ratios (> 0.5) are likely to significantly modulate liver (AUCR > 1.25) and renal (ΔCL_renal  > 25%) biomarkers and evoke DDI risk. The % inhibition approach supports integration of liver and renal SLC data and allows one to generate pan-SLC inhibition signatures for different test perpetrators (e.g., SLC % inhibition ranking). In turn, such signatures can guide the selection of the most appropriate individual (or combinations of) biomarkers for testing in phase I studies.

Targeted Cancer Therapies Causing Elevations in Serum Creatinine Through Tubular Secretion Inhibition: A Case Report and Review of the Literature

Rationale:

Targeted cancer therapies have revolutionized the field of oncology by selecting for specific molecular pathways, thus improving overall clinical prognosis. However, many of these targeted treatments have been reported to have adverse kidney effects, including acute kidney injury, interstitial nephritis, and glomerular disease. Furthermore, some of these targeted therapies have also been found to cause an asymptomatic rise in serum creatinine levels through inhibition of active tubular secretion.

Presenting concerns:

A 79-year-old woman was being followed for stage 4 A2 chronic kidney disease secondary to type 2 diabetes and longstanding hypertension. She was diagnosed with invasive mammary carcinoma and was initiated on letrozole, an aromatase inhibitor, and palbociclib, a selective cyclin-dependent kinase inhibitor, was subsequently added. Prior to the initiation of her treatments, her baseline estimated glomerular filtration rate (eGFR) fluctuated between 25 and 28 mL/min/1.73 m² over the previous year. After initiating palbociclib, her serum creatinine progressively increased, despite having well-controlled blood pressure and diabetes. In addition, there was no history of pre-renal events nor any sonographic evidence of obstruction. Within 7 months, her eGFR based on serum creatinine had decreased down to 12 mL/min/1.73 m².

Interventions:

Given that there were no clinical or other biochemical changes suggestive of worsening renal function, a serum cystatin C was measured using an immunoturbidimetric assay, which was 1.71 mg/L and correlated with an eGFR of 33 mL/min/1.73 m² based on the chronic kidney disease epidemiology collaboration (CKD-EPI) cystatin C equation (2012). This value was consistent with her previous baseline. Based on these findings, the significant decrease in eGFR measured by serum creatinine was attributed to the inhibitory effects of palbociclib on tubular creatinine secretion, rather than representing true kidney damage. Thus, a kidney biopsy was not performed in this context.

Outcomes:

Seven months later, a repeat serum cystatin C was repeated to assess for any worsening of the patient’s kidney function and revealed an eGFR of 35 mL/min/1.73 m² based on the CKD-EPI cystatin C equation (2012), thus revealing stable kidney function and reinforcing the inhibitory effects of palbociclib on tubular creatinine secretion through its direct effects on kidney transporters.

Teaching points:

This case report and literature review acknowledges the importance of using alternative methods of assessing kidney function when patients are undergoing targeted cancer therapies known to affect tubular creatinine secretion, which include cyclin-dependent kinase 4/6 inhibitors, poly(adenosine diphosphate-ribose) polymerase inhibitors, tyrosine kinase inhibitors, and mesenchymal-epithelial transition inhibitors. The use of non–creatinine-based markers of glomerular filtration rate (GFR), such as cystatin C and nuclear renal scans, will allow for more accurate estimation of kidney function in the appropriate setting, thus avoiding invasive diagnostic tests and unnecessary adjustments of treatment plans. However, certain targeted cancer therapies have also been proven to cause true kidney injury; therefore, physicians must still maintain a high degree of suspicion and consider invasive investigations and/or cessation or reduction of treatments when alternative measurements of kidney function do not suggest an underestimation of GFR via serum creatinine.

Challenges and Opportunities for Improved Drug-Drug Interaction Predictions for Renal OCT2 and MATE1/2-K Transporters

Transporters contribute to renal elimination of drugs; therefore drug disposition can be impacted if transporters are inhibited by comedicant drugs. Regulatory agencies have provided guidelines to assess potential drug-drug interaction (DDI) risk for renal organic cation transporter 2 (OCT2) and multidrug and toxin extrusion 1 and 2-K (MATE1/2-K) transporters. Despite this, there are challenges with translating in vitro data using currently available tools to obtain a quantitative assessment of DDI risk in the clinic. Given the high number of drugs and new molecular entities showing in vitro inhibition toward OCT2 and/or MATE1/2-K and the lack of translation to clinically significant effects, it is reasonable to question whether the current in vitro assay design and modeling practice has led to unnecessary clinical evaluation. The aim of this review is to assess and discuss available in vitro and clinical data along with prediction models intended to provide clinical context of risk, including static models proposed by regulatory agencies and physiologically-based pharmacokinetic models, in order to identify best practices and areas of future opportunity. This analysis highlights that different in vitro assay designs, including substrate and cell systems used, strongly influence the derived concentration of drug producing 50% inhibition values and contribute to high variability observed across laboratories. Furthermore, the lack of sensitive index substrates coupled with specific inhibitors for individual transporters necessitates the use of complex models to evaluate clinical DDI risk.

Experimental and modeling evidence supporting the trans-inhibition mechanism for preincubation time-dependent, long-lasting inhibition of organic anion transporting polypeptide (OATP) 1B1 by cyclosporine A

Cyclosporine A (CsA) and rifampin are potent inhibitors of organic anion transporting polypeptide (OATP) 1B1 and are widely used to assess the risk for drug-drug interactions. CsA displays preincubation time-dependent, long-lasting inhibition of OATP1B1 in vitro and in rats in vivo, and a proposed mechanism is the trans-inhibition by which CsA inhibits OATP1B1 from the inside of cells. The current study aimed to experimentally validate the proposed mechanism using HEK293 cells stably expressing OATP1B1. The uptake of CsA reached a plateau following around 60-min incubation, with the cell-to-buffer concentration ratio of 3930, reflective of the high-affinity, high-capacity intracellular binding of CsA. The time course of CsA uptake was analyzed to estimate the kinetic parameters for permeability clearance and intracellular binding. When the OATP1B1-mediated uptake of [³H]estradiol-17β-glucuronide was measured following preincubation with CsA for 5 to 120 min, apparent K_i values became lower with longer preincubation. Our kinetic modeling incorporated the two reversible inhibition constants [K_i,trans and K_i,cis for the inhibition from inside (trans-inhibition) and outside (cis-inhibition) of cells, respectively] and estimated K_i,trans value of CsA was smaller by 48-fold than the estimated K_i,cis value. Rifampin also displayed preincubation time-dependent inhibition of OATP1B1, albeit the extent of enhancement was only 2-fold. The current study provides experimental evidence for the preincubation time-dependent shift of apparent K_i values and a mechanistic basis for physiologically based pharmacokinetic modeling that incorporates permeability clearance, extensive intracellular binding, and asymmetry of K_i values between the inside and outside of cells. Significance Statement In vitro data and kinetic modeling support that preincubation time-dependent, long-lasting inhibition of OATP1B1 by CsA can be explained by the extensive intracellular binding and reversible OATP1B1 inhibition intracellularly (trans-inhibition) as well as extracellularly (cis-inhibition). For inhibitors to display time-dependency, the following factors were found important: time to reach a steady-state cellular concentration, trans-inhibition potency relative to cis-inhibition, and the degree of cellular inhibitor accumulation. This study would aid in the accurate prediction of drug-drug interactions mediated by OATP1B1 inhibition.

Evaluation of Platinum Anticancer Drug-Induced Kidney Injury in Primary Culture of Rat Kidney Tissue Slices by Using Gas-Permeable Plates

The type of method adopted for the evaluation of drug-induced kidney injury (DIKI) plays an important role during the drug discovery process. In the present study, the usefulness of cultured rat kidney tissue slices maintained on gas-permeable poly(dimethylsiloxane) (PDMS) plates for DIKI was assessed by monitoring the ATP content as a marker of cell viability. The amount of ATP in the kidney slices cultured on the PDMS plates was higher than that in the slices cultured on gas-impermeable polystyrene plates. The protein expression of organic cation transporter-2 (Oct2) was maintained for 3 d. Cisplatin showed a time- and concentration-dependent reduction in ATP in the slices with a half-effective concentration value of 24 µM, which was alleviated by cimetidine, an Oct2 inhibitor, suggesting that cisplatin-induced kidney injury in the cultured slices was regulated by the basolateral uptake transporter Oct2. Furthermore, the intensity of platinum anticancer drug-induced nephrotoxicity in the cultured slices was consistent with that of the in vivo study. In conclusion, the primary culture of rat kidney tissue slices on gas-permeable plates is expected to aid in the prediction of the extent of nephrotoxicity of drugs, even when transporters are responsible for the accumulation of drugs in kidney tissues.

Safety of Tepotinib in Patients with MET Exon 14 Skipping NSCLC and Recommendations for Management

INTRODUCTION

The MET inhibitor tepotinib demonstrated durable clinical activity in patients with advanced MET exon 14 (METex14) skipping NSCLC. We report detailed analyses of adverse events of clinical interest (AECIs) in VISION, including edema, a class effect of MET inhibitors.

PATIENTS AND METHODS

Incidence, management, and time to first onset/resolution were analyzed for all-cause AECIs, according to composite categories (edema, hypoalbuminemia, creatinine increase, and ALT/AST increase) or individual preferred terms (pleural effusion, nausea, diarrhea, and vomiting), for patients with METex14 skipping NSCLC in the phase II VISION trial.

RESULTS

Of 255 patients analyzed (median age: 72 years), edema, the most common AECI, was reported in 69.8% (grade 3, 9.4%; grade 4, 0%). Median time to first edema onset was 7.9 weeks (range: 0.1-58.3). Edema was manageable with supportive measures, dose reduction (18.8%), and/or treatment interruption (23.1%), and rarely prompted discontinuation (4.3%). Other AECIs were also manageable and predominantly mild/moderate: hypoalbuminemia, 23.9% (grade 3, 5.5%); pleural effusion, 13.3% (grade ≥ 3, 5.1%); creatinine increase, 25.9% (grade 3, 0.4%); nausea, 26.7% (grade 3, 0.8%), diarrhea, 26.3% (grade 3, 0.4%), vomiting 12.9% (grade 3, 1.2%), and ALT/AST increase, 12.2% (grade ≥ 3, 3.1%). GI AEs typically occurred early and resolved in the first weeks.

CONCLUSION

Tepotinib was well tolerated in the largest trial of a MET inhibitor in METex14 skipping NSCLC. The most frequent AEs were largely mild/moderate and manageable with supportive measures and/or dose reduction/interruption, and caused few withdrawals in this elderly population.

The Interplay between Uremic Toxins and Albumin, Membrane Transporters and Drug Interaction

Uremic toxins are a heterogeneous group of molecules that accumulate in the body due to the progression of chronic kidney disease (CKD). These toxins are associated with kidney dysfunction and the development of comorbidities in patients with CKD, being only partially eliminated by dialysis therapies. Importantly, drugs used in clinical treatments may affect the levels of uremic toxins, their tissue disposition, and even their elimination through the interaction of both with proteins such as albumin and cell membrane transporters. In this context, protein-bound uremic toxins (PBUTs) are highlighted for their high affinity for albumin, the most abundant serum protein with multiple binding sites and an ability to interact with drugs. Membrane transporters mediate the cellular influx and efflux of various uremic toxins, which may also compete with drugs as substrates, and both may alter transporter activity or expression. Therefore, this review explores the interaction mechanisms between uremic toxins and albumin, as well as membrane transporters, considering their potential relationship with drugs used in clinical practice.

In Vitro and In Vivo Inhibition of MATE1 by Tyrosine Kinase Inhibitors

The membrane transport of many cationic prescription drugs depends on facilitated transport by organic cation transporters of which several members, including OCT2 (SLC22A2), are sensitive to inhibition by select tyrosine kinase inhibitors (TKIs). We hypothesized that TKIs may differentially interact with the renal transporter MATE1 (SLC47A1) and influence the elimination and toxicity of the MATE1 substrate oxaliplatin. Interactions with FDA-approved TKIs were evaluated in transfected HEK293 cells, and in vivo pharmacokinetic studies were performed in wild-type, MATE1-deficient, and OCT2/MATE1-deficient mice. Of 57 TKIs evaluated, 37 potently inhibited MATE1 function by >80% through a non-competitive, reversible, substrate-independent mechanism. The urinary excretion of oxaliplatin was reduced by about 2-fold in mice with a deficiency of MATE1 or both OCT2 and MATE1 (p < 0.05), without impacting markers of acute renal injury. In addition, genetic or pharmacological inhibition of MATE1 did not significantly alter plasma levels of oxaliplatin, suggesting that MATE1 inhibitors are unlikely to influence the safety or drug-drug interaction liability of oxaliplatin-based chemotherapy.

Tepotinib in patients with NSCLC harbouring MET exon 14 skipping: Japanese subset analysis from the Phase II VISION study

BACKGROUND

MET exon 14 skipping is an oncogenic driver occurring in 3-4% of non-small cell lung cancer (NSCLC). The MET inhibitor tepotinib has demonstrated clinical efficacy in patients with MET exon 14 skipping NSCLC. Here, we present data from Japanese patients in the Phase II VISION study, evaluating the efficacy and safety of tepotinib.

METHODS

In the open-label, single-arm, Phase II VISION study, patients with advanced/metastatic NSCLC with MET exon 14 skipping received oral tepotinib 500 mg once daily. The primary endpoint was objective response by independent review. Subgroup analyses of Japanese patients were preplanned.

RESULTS

As of 1 January 2020, 19 Japanese patients received tepotinib and were evaluated for safety, 15 of whom had ≥9 months' follow-up and were also analysed for efficacy. By independent review, objective response rate (ORR) was 60.0% (95% confidence interval [CI]: 32.3, 83.7), median duration of response was not reached (95% CI: 6.9, not estimable [ne]), and progression-free survival was 11.0 months (95% CI: 1.4, ne). ORR in patients with MET exon 14 skipping identified by liquid biopsy (n = 8) was 87.5% (95% CI: 47.3, 99.7), and by tissue biopsy (n = 12) was 50.0% (95% CI: 21.1, 78.9). Patients' quality of life was maintained with tepotinib treatment. Among patients evaluated for safety, the most common treatment-related adverse events (any grade) were blood creatinine increase and peripheral oedema (12 and nine patients, respectively).

CONCLUSIONS

Tepotinib demonstrated robust and durable clinical efficacy in Japanese patients with advanced NSCLC harbouring MET exon 14 skipping, identified by either liquid or tissue biopsy. The main adverse events, blood creatinine increase and peripheral oedema, were manageable.

Metabolomic and transcriptomic analysis reveals endogenous substrates and metabolic adaptation in rats lacking Abcg2 and Abcb1a transporters

Abcg2/Bcrp and Abcb1a/Pgp are xenobiotic efflux transporters limiting substrate permeability in the gastrointestinal system and brain, and increasing renal and hepatic drug clearance. The systemic impact of Bcrp and Pgp ablation on metabolic homeostasis of endogenous substrates is incompletely understood. We performed untargeted metabolomics of cerebrospinal fluid (CSF) and plasma, transcriptomics of brain, liver and kidney from male Sprague Dawley rats (WT) and Bcrp/Pgp double knock-out (dKO) rats, and integrated metabolomic/transcriptomic analysis to identify putative substrates and perturbations in canonical metabolic pathways. A predictive Bayesian machine learning model was used to predict in silico those metabolites with greater substrate-like features for either transporters. The CSF and plasma levels of 169 metabolites, nutrients, signaling molecules, antioxidants and lipids were significantly altered in dKO rats, compared to WT rats. These metabolite changes suggested alterations in histidine, branched chain amino acid, purine and pyrimidine metabolism in the dKO rats. Levels of methylated and sulfated metabolites and some primary bile acids were increased in dKO CSF or plasma. Elevated uric acid levels appeared to be a primary driver of changes in purine and pyrimidine biosynthesis. Alterations in Bcrp/Pgp dKO CSF levels of antioxidants, precursors of neurotransmitters, and uric acid suggests the transporters may contribute to the regulation of a healthy central nervous system in rats. Microbiome-generated metabolites were found to be elevated in dKO rat plasma and CSF. The altered dKO metabolome appeared to cause compensatory transcriptional change in urate biosynthesis and response to lipopolysaccharide in brain, oxidation-reduction processes and response to oxidative stress and porphyrin biosynthesis in kidney, and circadian rhythm genes in liver. These findings present insight into endogenous functions of Bcrp and Pgp, the impact that transporter substrates, inhibitors or polymorphisms may have on metabolism, how transporter inhibition could rewire drug sensitivity indirectly through metabolic changes, and identify functional Bcrp biomarkers.

Effects of SLC22A2 808G>T polymorphism and bosutinib concentrations on serum creatinine in patients with chronic myeloid leukemia receiving bosutinib therapy

The purpose of this study was to investigate the effects of SLC22A2 808G>T polymorphism and trough concentrations (C₀) of bosutinib on serum creatinine in 28 patients taking bosutinib. At 1, 3, 6, 12, 24, and 36 months after administration, analysis of bosutinib C₀ and creatinine was performed at the same time of day. Significant correlations were observed between bosutinib C₀ and the change rate of serum creatinine or the estimated glomerular filtration rate (eGFR; r = 0.328, P < 0.001 and r = − 0.315, P < 0.001, respectively). These correlations were particularly high in patients having the SLC22A2 808G/G genotype (r = 0.345 and r = − 0.329, respectively); however, in patients having the 808T allele, there were no significant differences. In multivariate analyses, the SLC22A2 808G/G genotype, patient age, bosutinib C₀ and second-line or later bosutinib were independent factors influencing the change rate of creatinine. Bosutinib elevated serum creatinine through organic cation transporter 2 (OCT2). We observed a 20% increase in serum creatinine with a median bosutinib C₀ of 63.4–73.2 ng/mL. Periodic measurement of serum creatinine after bosutinib therapy is necessary to avoid progression to severe renal dysfunction from simple elevation of creatinine mediated by OCT2 following bosutinib treatment.

Interactions of janus kinase inhibitors with drug transporters and consequences for pharmacokinetics and toxicity

Introduction: Janus kinase inhibitors (JAKinibs) constitute an emerging and promising pharmacological class of anti-inflammatory or anti-cancer drugs, used notably for the treatment of rheumatoid arthritis and some myeloproliferative neoplasms.Areas covered: This review provides an overview of the interactions between marketed JAKinibs and major uptake and efflux drug transporters. Consequences regarding pharmacokinetics, drug-drug interactions and toxicity are summarized.Expert opinion: JAKinibs interact in vitro with transporters in various ways, as inhibitors or as substrates of transporters or as regulators of transporter expression. This may theoretically result in drug-drug interactions (DDIs), with JAKinibs acting as perpetrators or as victims, or in toxicity, via impairment of thiamine transport. Clinical significance in terms of DDIs for JAKinib-transporter interactions remains however poorly documented. In this context, the in vivo unbound concentration of JAKinibs is likely a key parameter to consider for evaluating the clinical relevance of JAKinibs-mediated transporter inhibition. Additionally, the interplay with drug metabolism as well as possible interactions with transporters of emerging importance and time-dependent inhibition have to be taken into account. The role drug transporters may play in controlling cellular JAKinib concentrations and efficacy in target cells is also an issue of interest.

The effect of levamisole on kidney function in children with steroid-sensitive nephrotic syndrome

BACKGROUND

Levamisole is frequently used as a steroid-sparing agent in children with steroid-sensitive nephrotic syndrome. Side effects, such as neutropenia, gastro-intestinal upset and skin rash, have been reported. We noted an increase in creatinine in some of our patients, but literature on the effect of levamisole on kidney function is lacking.

METHODS

A retrospective cohort study was conducted, including patients 1-18 years of age, treated for steroid-sensitive nephrotic syndrome with levamisole at Great Ormond Street Hospital for Children between January 2010 and January 2020. Data was collected on clinical observations and serum creatinine values before, during and after treatment. eGFR was calculated using the Schwartz equation.

RESULTS

In total, 75 children were included in the analysis. The median duration of treatment was 19 (IQR 12-27) months. The median estimated GFR was 134 (IQR 119-160), 101 (IQR 91-113) and 116 (IQR 106-153) ml/min/1.73 m², respectively, before, during and after treatment with levamisole. The difference between eGFR before and after treatment compared with during treatment was statically significant (P < 0.0001). During the treatment period, the eGFR decrease was not progressive. The median levamisole dose was 2.5 (IQR 2.3-2.6) mg/kg on alternate days, and the dose was not correlated with the decrease in eGFR (r = 0.07, 95% CI - 0.22 to 0.35).

CONCLUSION

Levamisole significantly decreases eGFR. However, this decrease is not progressive or irreversible and would not be an indication to discontinue the treatment.

KDIGO Controversies Conference on onco-nephrology: understanding kidney impairment and solid-organ malignancies, and managing kidney cancer

The association between kidney disease and cancer is multifaceted and complex. Persons with chronic kidney disease (CKD) have an increased incidence of cancer, and both cancer and cancer treatments can cause impaired kidney function. Renal issues in the setting of malignancy can worsen patient outcomes and diminish the adequacy of anticancer treatments. In addition, the oncology treatment landscape is changing rapidly, and data on tolerability of novel therapies in patients with CKD are often lacking. Caring for oncology patients has become more specialized and interdisciplinary, currently requiring collaboration among specialists in nephrology, medical oncology, critical care, clinical pharmacology/pharmacy, and palliative care, in addition to surgeons and urologists. To identify key management issues in nephrology relevant to patients with malignancy, KDIGO (Kidney Disease: Improving Global Outcomes) assembled a global panel of multidisciplinary clinical and scientific expertise for a controversies conference on onco-nephrology in December 2018. This report covers issues related to kidney impairment and solid organ malignancies as well as management and treatment of kidney cancer. Knowledge gaps, areas of controversy, and research priorities are described.

Associations between plasma hydroxylated metabolite of itraconazole and serum creatinine in patients with a hematopoietic or immune-related disorder

PURPOSE

Serum markers of renal function have not been characterized in patients treated with itraconazole (ITZ). This study aimed to evaluate the associations between plasma ITZ and its hydroxylated metabolite (OH-ITZ) concentrations and serum markers of renal function in patients with hematopoietic or immune-related disorder.

METHODS

This study enrolled 40 patients with hematopoietic or immune-related disorder who are receiving oral ITZ solution. Plasma concentrations of ITZ and OH-ITZ at 12 h after dosing were determined at steady state. Their relationships with serum levels of creatinine and cystatin C and their estimated glomerular filtration rate (eGFR) were evaluated.

RESULTS

The free plasma concentration of ITZ had no correlation with serum creatinine and serum creatinine-based estimated glomerular filtration rate (eGFR-cre). The free plasma concentration of OH-ITZ was positively and negatively correlated with serum creatinine and eGFR-cre, respectively. The free plasma concentrations of ITZ and OH-ITZ had no association with serum cystatin C and serum cystatin C-based eGFR. Serum creatinine was higher by 16% after than before starting ITZ treatment, while eGFR-cre was lower by 9.3%. The serum creatinine ratio after/before ITZ treatment was positively correlated with the free plasma concentration of OH-ITZ. The patients co-treated with trimethoprim-sulfamethoxazole had higher serum creatinine. Concomitant glucocorticoid administration did not significantly alter serum cystatin C.

CONCLUSIONS

Patients with hematopoietic or immune-related disorder treated with oral ITZ had a higher level of serum creatinine. Although serum creatinine potentially increases in conjunction with the free plasma concentration of OH-ITZ, concomitant ITZ administration has a slight impact on the eGFR-cre level in clinical settings.

Tucatinib Inhibits Renal Transporters OCT2 and MATE Without Impacting Renal Function in Healthy Subjects

Tucatinib is a potent tyrosine kinase inhibitor selective for human epidermal growth factor receptor 2 (HER2) approved by the US Food and Drug Administration for the treatment of HER2‐positive metastatic breast cancer and in development for other HER2‐positive solid tumors. Modest, reversible serum creatinine (SCr) elevations have been observed in tucatinib clinical trials. SCr is conveyed by the renal drug transporters organic cation transporter 2 (OCT2) and multidrug and toxin extrusion protein 1 (MATE1) and 2‐K (MATE2‐K) and can increase in the presence of inhibitors of these transporters. In vitro, tucatinib inhibited OCT2‐, MATE1‐, and MATE2‐K‐mediated transport of metformin, with IC₅₀ values of 14.7, 0.340, and 0.135 µM, respectively. Tucatinib also inhibited OCT2‐ and MATE1‐mediated transport of creatinine, with IC₅₀ values of 0.107 and 0.0855 µM, respectively. A phase 1 study with metformin administered orally in the absence and presence of tucatinib was conducted in 18 healthy subjects. Renal function was assessed by measuring glomerular filtration rate (GFR; based on iohexol plasma clearance) and endogenous markers (SCr, cystatin C‐based estimated glomerular filtration rate [eGFR]) with and without tucatinib. Metformin exposure increased (1.4‐fold) and renal clearance decreased (29.99‐17.64 L/h) with tucatinib, with no effect on metformin maximum concentration. Creatinine clearance transiently decreased 23% with tucatinib. GFR and eGFR, which are unaffected by OCT2 and/or MATE1/2‐K transport, were unchanged with tucatinib. These data demonstrate that tucatinib inhibits OCT2‐ and MATE1/2‐K‐mediated tubular secretion of creatinine, which may manifest as mild SCr elevations that are not indicative of renal impairment.

Pharmacokinetic-Based Drug-Drug Interactions with Anaplastic Lymphoma Kinase Inhibitors: A Review

Anaplastic lymphoma kinase (ALK) inhibitors are important treatment options for non-small-cell lung cancer (NSCLC), associated with ALK gene rearrangement. Patients with ALK gene rearrangement show sensitivity to and benefit clinically from treatment with ALK tyrosine kinase inhibitors (ALK-TKIs). To date, crizotinib, ceritinib, alectinib, brigatinib, lorlatinib, and entrectinib have received approval from the US Food and Drug Administration and/or the European Medicines Agency for use during the treatment of ALK-gene-rearrangement forms of NSCLC. Although the oral route of administration is convenient and results in good compliance among patients, oral administration can be affected by many factors, such as food, intragastric pH, cytochrome P450 enzymes, transporters, and p-glycoprotein. These factors can result in increased risks for serious adverse events or can lead to reduced therapeutic effects of ALK-TKIs. This review characterizes and summarizes the pharmacokinetic parameters and drug–-drug interactions associated with ALK-TKIs to provide specific recommendations for oncologists and clinical pharmacists when prescribing ALK-TKIs.

Role of SLC transporters in toxicity induced by anticancer drugs

INTRODUCTION

. Membrane transporters are integral to the maintenance of cellular integrity of all tissue and cell types. While transporters play an established role in the systemic pharmacokinetics of therapeutic drugs, tissue specific expression of uptake transporters can serve as an initiating mechanism that governs the accumulation and impact of cytotoxic drugs.

AREAS COVERED

. This review provides an overview of organic cation transporters as determinants of chemotherapy-induced toxicities. We also provide insights into the recently updated FDA guidelines for in vitro drug interaction studies, with a particular focus on the class of tyrosine kinase inhibitors as perpetrators of transporter-mediated drug interactions.

EXPERT OPINION

. Studies performed over the last few decades have highlighted the important role of basolateral uptake and apical efflux transporters in the pathophysiology of drug-induced organ damage. Increased understanding of the mechanisms that govern the accumulation of cytotoxic drugs has provided insights into the development of novel strategies to prevent debilitating toxicities. Furthermore, we argue that current regulatory guidelines provide inadequate recommendations for in vitro studies to identify substrates or inhibitors of drug transporters. Therefore, the translational and predictive power of FDA-approved drugs as modulators of transport function remains ambiguous and warrants further revision of the current guidelines.

Entrectinib for the treatment of metastatic NSCLC: safety and efficacy

Introduction: Gene fusions are strong driver alterations in various cancers, increasingly diagnosed with multiple testing techniques. ROS1 fusions can be found in 1-2% of non-small cell lung cancer (NSCLC) and several tyrosine kinase inhibitors (TKIs) have been tested in this oncogene-driven disease. NTRK fusions are characteristic of a few rare types of cancer, also infrequently seen in some common cancers including NSCLC. Entrectinib is a newer ROS1 and NTRK inhibitor developed across different tumor types harboring rearrangements in these genes. Entrectinib was granted FDA accelerated approval in August 2019 for the treatment of ROS1+ NSCLC and NTRK-driven solid tumors.Areas covered: This review covers the mechanism of action, safety, and efficacy of entrectinib in patients with metastatic NSCLC.Expert opinion: Entrectinib is an orally bioavailable TKI of TrkA, TrkB, TrkC, and ROS1, with the ability to cross the blood-brain barrier. Entrectinib was effective and well-tolerated in patients harboring ROS1- or NTRK-rearranged NSCLC treated within phase I and II studies. Entrectinib appears to be the most appropriate treatment choice for TKIs-naïve patients, especially in those presenting brain metastasis. Conversely, in case of systemic progression with the evidence of acquired resistance mutations in ROS1 or Trk proteins, a sequential therapy with entrectinib could not be successful.

Creatinine: From physiology to clinical application

Estimating static kidney function accurately and detecting changes in kidney function in a timely fashion are challenging but critically important tasks. Serum creatinine is the most widely used functional biomarker of the kidney. However, its use is associated with substantial shortcomings. Understanding these shortcomings is critical in allowing accurate interpretation of creatinine values and translating them into changes in kidney function. In this review, the pathways involved in creatinine generation and metabolism as well as the techniques involved in measuring creatinine concentrations are discussed. This allows for the discussion of the value and pitfalls in using creatinine as a marker of kidney function. In addition, information regarding alternative functional biomarkers of the kidney is provided.

Management of Presumed Acute Kidney Injury during Hypertensive Therapy: Stay Calm and Carry on?

BACKGROUND

Recent studies have demonstrated that intensive blood pressure control is associated with improved cardiovascular outcomes. Acute kidney injury (AKI), however, was more common in the intensive treatment group prompting concern in the nephrology community.

SUMMARY

Clinical trials on hypertension control have traditionally defined AKI by changes in serum creatinine. However, serum creatinine has several inherent limitations as a marker of kidney injury, with various factors influencing its production, secretion, and elimination. Urinary biomarkers of kidney injury and repair have the potential to provide insight on the presence and phenotype of kidney injury. In both the Systolic Blood Pressure Intervention Trial and the Action to Control Cardiovascular Risk in Diabetes study, urinary biomarkers have suggested that the increased risk of AKI associated with intensive treatment was due to hemodynamic changes rather than structural kidney injury. As such, clinicians who encounter rises in serum creatinine during intensification of hypertension therapy should "stay calm and carry on." Alternative explanations for serum creatinine elevation should be considered and addressed if appropriate. When the rise in serum creatinine is limited, particularly if albuminuria is stable or improving, intensive blood pressure control should be continued for its potential long-term benefits. Key Messages: Increases in serum creatinine during intensification of blood pressure control may not necessarily reflect kidney injury. Clinicians should evaluate for other contributing factors before stopping therapy. Urinary biomarkers may address limitations of serum creatinine as a marker of kidney injury.

Interaction between phytotherapy and oral anticancer agents: prospective study and literature review

Cancer is becoming more prevalent in elderly patient. Due to polypharmacy, older adults with cancer are predisposed to drug-drug interactions. There is also an increasing interest in the use of complementary and alternative medicine (CAM). Thirty to seventy percent of patients with cancer have used CAM. Through pharmaceutical counseling sessions, we can provide advices on herb-drug interactions (HDI). All the patients seen in pharmaceutical counseling sessions were prospectively included. Information was collected during these sessions: prescribed medication (oral anticancer agents (OAA) and other drugs), CAM (phytotherapy especially), and use of over-the-counter (OTC) drugs. If pharmacist considered an interaction or an intervention clinically relevant, the oncologist was notified. Then, a literature review was realized to identify the potential HDI (no interactions, precautions for use, contraindication). Among 201 pharmacist counseling sessions, it resulted in 104 interventions related to 46 HDI, 28 drug-drug interactions and 30 others (wrong dosage, omission…). To determine HDI, we review 73 medicinal plants which are used by our patients with cancer and 31 OAA. A total of 1829 recommendations were formulated about 59 (75%) medical plants and their interaction with an OAA. Herb-drug interactions should not be ignored by healthcare providers in their management of cancer patients in daily practice.

Changes of drug pharmacokinetics mediated by downregulation of kidney organic cation transporters Mate1 and Oct2 in a rat model of hyperuricemia

The effects of hyperuricemia on the expression of kidney drug transporters and on the pharmacokinetics of several substrate drugs were examined. We first established a rat model of hyperuricemia without marked symptoms of chronic kidney failure by 10-day co-administration of oxonic acid (uricase inhibitor) and adenine (biosynthetic precursor of uric acid). These hyperuricemic rats showed plasma uric acid concentrations of up to 6 mg/dL, which is similar to the serum uric acid level in hyperuricemic humans, with little change of inulin clearance. The mRNA levels of multidrug and toxin extrusion 1 (Mate1, Slc47a1), organic anion transporter 1 (Oat1, Slc22a6), organic cation transporter 2 (Oct2, Slc22a2), urate transporter 1 (Urat1, Slc22a12) and peptide transporter 1 (Pept1, Slc15a1) were significantly decreased in kidney of hyperuricemic rats. Since Oct2, Mate1 and Oat1 are important for renal drug elimination, we next investigated whether the pharmacokinetics of their substrates, metformin, cephalexin and creatinine, were altered. The plasma concentration of metformin was not affected, while its kidney tissue accumulation was significantly increased. The plasma concentration and kidney tissue accumulation of cephalexin and the plasma concentration of creatinine were also increased. Furthermore, the protein expression of kidney Mate1 was decreased in hyperuricemic rats. Accordingly, although multiple factors may influence renal handling of these drugs, these observations can be accounted for, at least in part, by downregulation of Mate1-mediated apical efflux from tubular cells and Oct2-mediated basolateral uptake. Our results suggest that hyperuricemia could alter the disposition of drugs that are substrates of Mate1 and/or Oct2.