Effects of Food, Gastric Acid Reduction, and Strong CYP3A Induction on the Pharmacokinetics of Tasurgratinib, a Novel Selective Fibroblast Growth Factor Receptor Inhibitor

We conducted this three-part study in healthy subjects to investigate the pharmacokinetics of tasurgratinib (orally available selective inhibitor of fibroblast growth factor receptor 1-3) and M2 (its major metabolite) under different conditions. In Part A, subjects received tasurgratinib 35 mg either fed with a high-fat meal or fasted. In Parts B and C, subjects received tasurgratinib 35 mg alone or with either rabeprazole (acid-reducing agent) 20 mg (Part B) or rifampin (strong CYP3A inducer) 600 mg (Part C). Primary endpoints were maximum concentration (Cmax), and areas under the plasma concentration-time curve to time of last quantifiable concentration (AUC(0-t)) and extrapolated to infinite time (AUC(0-inf)). Forty-two subjects were enrolled, 14 each into Parts A, B, and C. In Part A, administration of tasurgratinib with a high-fat meal resulted in 33% reduction in Cmax and ∼23% reduction in AUC(0-t) and AUC(0-inf) of tasurgratinib, and 47% reduction in Cmax with ∼30% reduction in AUC(0-t) and AUC(0-inf) of M2. In Part B, co-administration of rabeprazole at steady state resulted in no/weak interaction with tasurgratinib (∼8% increase in AUC(0-t) and AUC(0-inf) without an effect on Cmax) and M2 (∼18% increase in AUC(0-t) and AUC(0-inf) without an effect on Cmax). In Part C, co-administration of rifampin at steady state resulted in a weak interaction with tasurgratinib (∼16% reduction in AUC(0-t) and AUC(0-inf)) and M2 (∼12% reduction in AUC(0-t) and AUC(0-inf)). Administration of tasurgratinib with a high-fat meal appeared to reduce systemic exposure of tasurgratinib, however co-administration with an acid-reducing agent or a CYP3A inducer had a minimal impact on pharmacokinetics.

Physiologically based pharmacokinetic modeling of CYP2C8 substrate rosiglitazone and its metabolite to predict metabolic drug-drug interaction

Rosiglitazone is an activator of nuclear peroxisome proliferator-activated (PPAR) receptor gamma used in the treatment of type 2 diabetes mellitus. The elimination of rosiglitazone occurs mainly via metabolism, with major contribution by enzyme cytochrome P450 (CYP) 2C8. Primary routes of rosiglitazone metabolism are N-demethylation and hydroxylation. Modulation of CYP2C8 activity by co-administered drugs lead to prominent changes in the exposure of rosiglitazone and its metabolites. Here, we attempt to develop mechanistic parent-metabolite physiologically based pharmacokinetic (PBPK) model for rosiglitazone. Our goal is to predict potential drug-drug interaction (DDI) and consequent changes in metabolite N-desmethyl rosiglitazone exposure. The PBPK modeling was performed in the PKSim® software using clinical pharmacokinetics data from literature. The contribution to N-desmethyl rosiglitazone formation by CYP2C8 was delineated using vitro metabolite formation rates from recombinant enzyme system. Developed model was verified for prediction of rosiglitazone DDI potential and its metabolite exposure based on observed clinical DDI studies. Developed model exhibited good predictive performance both for rosiglitazone and N-desmethyl rosiglitazone respectively, evaluated based on commonly acceptable criteria. In conclusion, developed model helps with prediction of CYP2C8 DDI using rosiglitazone as a substrate, as well as changes in metabolite exposure. In vitro data for metabolite formation can be successfully utilized to translate to in vivo conditions.

Anti-Angiogenic Tyrosine Kinase Inhibitor-Related Toxicities Among Cancer Patients: A Systematic Review and Meta-Analysis

BACKGROUND

Targeting of angiogenesis has become a major therapeutic approach for the treatment of various advanced cancers. There are many unresolved questions on the toxicity of anti-angiogenic tyrosine kinase inhibitors (TKIs).

OBJECTIVE

We performed a meta-analysis to assess the toxicity prevalence of the different anti-angiogenic TKIs among cancer patients and in subpopulations of interest including patients with renal cell carcinoma.

PATIENTS AND METHODS

We searched the MEDLINE and Cochrane Library databases to November 2023. Clinical trials were eligible if they set out to report the grade ≥3 toxicities related to one of the seven currently approved anti-angiogenic TKIs as monotherapies. The Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) method was applied with PROSPERO (CRD42023411946).

RESULTS

The 421 eligible studies included a total of 56,895 cancer patients treated with anti-angiogenic TKI monotherapy. Twenty-four different cancer types were identified, mainly renal cell carcinoma (41.9% of the patients). The anti-angiogenic TKI was sorafenib (34.5% of the patients), sunitinib (30.5%), regorafenib (10.7%), pazopanib (9.4%), cabozantinib (7.7%), axitinib (4.3%), and lenvatinib (2.9%). The pooled prevalence of grade 3 and 4 toxicities was 56.1% (95% confidence interval 53.5-58.6), with marked between-study heterogeneity (I2 = 96.8%). Toxicity profiles varied considerably depending on the type of TKI, the cancer type, and the specific patient characteristics. In particular, Asian patients and elderly people had higher prevalences of severe toxicities, with pazopanib being the best-tolerated drug. For patients treated with sunitinib, particularly those with metastatic RCC, there was no significant difference in terms of toxicity according to the regimen schedule.

CONCLUSIONS

This meta-analysis highlights the toxicity profiles of anti-angiogenic TKI monotherapies, and thus enables high-level recommendations for the choice of anti-angiogenic TKIs on the basis of the patient's age, ethnicity, comorbidities, and comedications, for personalized treatment.

Higher risk of hepatotoxicity associated with cabozantinib in cancer patients

BACKGROUND

The efficacy of cabozantinib has attracted interest in various solid tumors. The primary aim of this study was to evaluate the risk of hepatotoxicity associated with cabozantinib in the patients with cancer.

METHODS

PubMed, Cochrane, and EMBASE databases were searched for published randomized controlled trials (RCTs) from inception to September 9, 2023. The mainly outcomes were all-grade and grade ≥3 elevation of aspartate aminotransferase (AST) and alanine aminotransferase (ALT), expressed as relative risk (RR) and 95% confidence interval (CI). All data were pooled using fixed-effect or random-effects models according to the heterogeneity of the included RCTs.

RESULTS

Among the 922 records identified, 8 RCTs incorporating 2613 patients with cancer were included. For patients receiving cabozantinib, the relative risks of all-grade AST elevation (RR, 2.63; 95% CI, 2.16-3.20, P < 0.001), all-grade ALT elevation (RR, 2.89; 95% CI, 2.31-3.60, P < 0.001), grade ≥3 AST elevation (RR, 2.26; 95% CI, 1.34-3.83, P = 0.002), and grade ≥3 ALT elevation (RR, 3.40; 95% CI, 1.65-7.01, P < 0.001) were higher than those of patients who did not receive cabozantinib group. Further subgroup analysis showed that the relative risk of hepatotoxicity associated with cabozantinib was higher than that in the other TKIs (erlotinib, sunitinib, and sorafenib) and the non-TKI drug groups (everolimus, prednisone, mitoxantrone, and paclitaxel).

CONCLUSIONS

Compared with other solid tumor drugs, such as everolimus, sorafenib, sunitinib, paclitaxel, mitoxantrone-prednisone et al., cabozantinib has a higher risk of hepatotoxicity.

Predicting Drug-Drug Interactions Involving Rifampicin Using a Semi-mechanistic Hepatic Compartmental Model

AIMS

To develop a semi-mechanistic hepatic compartmental model to predict the effects of rifampicin, a known inducer of CYP3A4 enzyme, on the metabolism of five drugs, in the hope of informing dose adjustments to avoid potential drug-drug interactions.

METHODS

A search was conducted for DDI studies on the interactions between rifampicin and CYP substrates that met specific criteria, including the availability of plasma concentration-time profiles, physical and absorption parameters, pharmacokinetic parameters, and the use of healthy subjects at therapeutic doses. The semi-mechanistic model utilized in this study was improved from its predecessors, incorporating additional parameters such as population data (specifically for Chinese and Caucasians), virtual individuals, gender distribution, age range, dosing time points, and coefficients of variation.

RESULTS

Optimal parameters were identified for our semi-mechanistic model by validating it with clinical data, resulting in a maximum difference of approximately 2-fold between simulated and observed values. PK data of healthy subjects were used for most CYP3A4 substrates, except for gilteritinib, which showed no significant difference between patients and healthy subjects. Dose adjustment of gilteritinib co-administered with rifampicin required a 3-fold increase of the initial dose, while other substrates were further tuned to achieve the desired drug exposure.

CONCLUSIONS

The pharmacokinetic parameters AUCR and CmaxR of drugs metabolized by CYP3A4, when influenced by Rifampicin, were predicted by the semi-mechanistic model to be approximately twice the empirically observed values, which suggests that the semi-mechanistic model was able to reasonably simulate the effect. The doses of four drugs adjusted via simulation to reduce rifampicin interaction.

Phase I Trial of the Multi-kinase Inhibitor Cabozantinib, a CYP3A4 Substrate, plus CYP3A4-Interacting Antiretroviral Therapy in People Living with HIV and Cancer (AMC-087)

PURPOSE

To evaluate the safety, pharmacokinetics, and pharmacodynamic effects of cabozantinib, a CYP3A4 substrate, in people living with human immunodeficiency virus and cancer receiving antiretrovirals (ARV).

PATIENTS AND METHODS

Patients received a reduced dose of cabozantinib (20 mg orally daily) with strong CYP3A4 inhibitors (ARV ritonavir or non-ARV cobicistat, stratum A), or a standard 60 mg dose with ARVs that are CYP3A4 inducers (efavirenz or etravirine, stratum B) or noninteracting ARVs (stratum C). Initial dose escalation in stratum A and stratum B was performed on the basis of tolerability.

RESULTS

36 patients received cabozantinib plus ARVs, including 20 in stratum A, 9 in B, and 7 in C. The recommended initial cabozantinib doses for stratum A, B, and C were 20, 60, and 60 mg, respectively. Doses of 40 or 60 mg plus CYP3A4 inhibitors in stratum A and 100 mg plus CYP3A4 inducers in stratum B were associated with excessive toxicity, whereas 60 mg with noninteracting ARVs was not. The steady state minimal concentrations were lower at 20 mg in stratum A or 60 mg in stratum B compared with 60 mg in stratum C, while total exposure was only lower in 60 mg in stratum B compared with 60 mg in stratum C. Activity was observed in Kaposi sarcoma and an AXL-amplified sarcoma.

CONCLUSIONS

Cabozantinib as a single agent should be initiated at 20 mg daily and 60 mg daily when taken concurrently with ARVs that are strong CYP3A4 inhibitors and inducers, respectively, with consideration for subsequent escalation per current cabozantinib guidelines. See related commentary by Eisenmann and Sparreboom, p. 4999.

Unique Cabozantinib Dosing Considerations in People Living with HIV and Cancer

A recent article characterized dosing recommendations for cabozantinib in people living with HIV (PLWH) and cancer, a group that is often excluded from clinical trials. This study suggests cabozantinib is effective in cancers disproportionately impacting PLWH and has translational implications for the design of studies evaluating drug-drug interactions. See related article by Haigentz et al., p. 5038.

Local Liver Irradiation Concurrently Versus Sequentially with Cabozantinib on the Pharmacokinetics and Biodistribution in Rats

The aim of this study was to evaluate the radiotherapy (RT)-pharmacokinetics (PK) effect of cabozantinib in concurrent or sequential regimens with external beam radiotherapy (EBRT) or stereotactic body radiation therapy (SBRT). Concurrent and sequential regimens involving RT and cabozantinib were designed. The RT–drug interactions of cabozantinib under RT were confirmed in a free-moving rat model. The drugs were separated on an Agilent ZORBAX SB-phenyl column with a mobile phase consisting of 10 mM potassium dihydrogen phosphate (KH2PO4)–methanol solution (27:73, v/v) for cabozantinib. There were no statistically significant differences in the concentration versus time curve of cabozantinib (AUCcabozantinib) between the control group and the RT2Gy×3 f’x and RT9Gy×3 f’x groups in the concurrent and the sequential regimens. However, compared to those in the control group, the Tmax, T1/2 and MRT decreased by 72.8% (p = 0.04), 49.0% (p = 0.04) and 48.5% (p = 0.04) with RT2Gy×3 f’x in the concurrent regimen, respectively. Additionally, the T1/2 and MRT decreased by 58.8% (p = 0.01) and 57.8% (p = 0.01) in the concurrent RT9Gy×3 f’x group when compared with the control group, respectively. The biodistribution of cabozantinib in the heart increased by 271.4% (p = 0.04) and 120.0% (p = 0.04) with RT2Gy×3 f’x in the concurrent and sequential regimens compared to the concurrent regimen, respectively. Additionally, the biodistribution of cabozantinib in the heart increased by 107.1% (p = 0.01) with the RT9Gy×3 f’x sequential regimen. Compared to the RT9Gy×3 f’x concurrent regimen, the RT9Gy×3 f’x sequential regimen increased the biodistribution of cabozantinib in the heart (81.3%, p = 0.02), liver (110.5%, p = 0.02), lung (125%, p = 0.004) and kidneys (87.5%, p = 0.048). No cabozantinib was detected in the brain in any of the groups. The AUC of cabozantinib is not modulated by irradiation and is not affected by treatment strategies. However, the biodistribution of cabozantinib in the heart is modulated by off-target irradiation and SBRT doses simultaneously. The impact of the biodistribution of cabozantinib with RT9Gy×3 f’x is more significant with the sequential regimen than with the concurrent regimen.

Cabozantinib, Vandetanib, Pralsetinib and Selpercatinib as Treatment for Progressed Medullary Thyroid Cancer with a Main Focus on Hypertension as Adverse Effect

This manuscript investigates cabozantinib, vandetanib, pralsetinib, and selpercatinib, four tyrosine kinase inhibitors (TKIs), which are used to treat advanced and/or metastatic medullary thyroid cancer (MTC). Data on efficacy and safety are presented with the main focus on treatment-related hypertension, a well-known adverse effect (AE) of these TKIs. Taken together, TKI-induced hypertension is rarely a dose-limiting side effect. However, with increasing survival times of patients under treatment, hypertension-associated complications can be expected to be on the rise without proper medication.

Involvement of Transporters in Intestinal Drug-Drug Interactions of Oral Targeted Anticancer Drugs Assessed by Changes in Drug Absorption Time

(1) Background: Oral targeted anticancer drugs are victims of presystemic pharmacokinetic drug−drug interactions (DDI). Identification of the nature of these DDIs, i.e., enzyme-based or/and transporter-based, is challenging, since most of these drugs are substrates of intestinal and/or hepatic cytochrome P-450 enzymes and of intestinal membrane transporters. (2) Methods: Variations in mean absorption time (MAT) between DDIs and control period (MAT ratios < 0.77 or >1.30) have been proposed to implicate transporters in DDIs at the intestinal level. This methodology has been applied to a large set of oral targeted anticancer drugs (n = 54, involved in 77 DDI studies), from DDI studies available either in the international literature and/or in publicly accessible FDA files. (3) Results: Significant variations in MAT were evidenced in 33 DDI studies, 12 of which could be explained by modulation of an efflux transporter. In 21 DDI studies, modulation of efflux transporters could not explain the MAT variation, suggesting a possible relevant role of influx transporters in the intestinal absorption. (4) Conclusions: This methodology allows one to suggest the involvement of intestinal transporters in DDIs, and should be used in conjunction with in vitro methodologies to help understanding the origin of DDIs.

Gefitinib Inhibits Rifampicin-Induced CYP3A4 Gene Expression in Human Hepatocytes

During multidrug combination chemotherapy, activation of the nuclear receptor and the transcription factor human pregnane xenobiotic receptor (hPXR) has been shown to play a role in the development of chemoresistance. Mechanistically, this could occur due to the cancer drug activation of hPXR and the subsequent upregulation of hPXR target genes such as the drug metabolism enzyme, cytochrome P450 3A4 (CYP3A4). In the context of hPXR-mediated drug resistance, hPXR antagonists would be useful adjuncts to PXR-activating chemotherapy. However, there are currently no clinically approved hPXR antagonists in the market. Gefitinib (GEF), a tyrosine kinase inhibitor used for the treatment of advanced non-small-cell lung cancer and effectively used in combinational chemotherapy treatments, is a promising candidate owing to its hPXR ligand-like features. We, therefore, investigated whether GEF would act as an hPXR antagonist when combined with a known hPXR agonist, rifampicin (RIF). At therapeutically relevant concentrations, GEF successfully inhibited the RIF-induced upregulation of endogenous CYP3A4 gene expression in human primary hepatocytes and human hepatocells. Additionally, GEF inhibited the RIF induction of hPXR-mediated CYP3A4 promoter activity in HepG2 human liver carcinoma cells. The computational modeling of molecular docking predicted that GEF could bind to multiple sites on hPXR including the ligand-binding pocket, allowing for potential as a direct antagonist as well as an allosteric inhibitor. Indeed, GEF bound to the ligand-binding domain of the hPXR in cell-free assays, suggesting that GEF directly interacts with the hPXR. Taken together, our results suggest that GEF, at its clinically relevant therapeutic concentration, can antagonize the hPXR agonist-induced CYP3A4 gene expression in human hepatocytes. Thus, GEF could be a potential candidate for use in combinational chemotherapies to combat hPXR agonist-induced chemoresistance. Further studies are warranted to determine whether GEF has sufficient hPXR inhibitor abilities to overcome the hPXR agonist-induced chemoresistance.

Cabozantinib Carries the Risk of Drug-Drug Interactions via Inhibition of UDPglucuronosyltransferase (UGT) 1A9

BACKGROUND

Cabozantinib is a multiple receptor tyrosine kinases inhibitor (TKI) approved to treat progressive, metastatic medullary thyroid cancer, advanced renal cell carcinoma, and hepatocellular carcinoma. Drugdrug interactions (DDIs) for cabozantinib have been identified involving the role of cytochromes P450. Although the previous study reported that cabozantinib showed a slight inhibition of UDP-glucuronosyltransferase (UGT) 1A1 at the highest concentration tested, there are no reports on the potential for UGTs-mediated-DDIs. Hence, the current study aims to address this knowledge gap.

OBJECTIVE

This study aimed to investigate the inhibitory effect of cabozantinib on human UGTs and to quantitatively evaluate the DDI potential via UGT inhibition.

METHODS

The inhibitory effects of cabozantinib on UGTs were determined by measuring the formation rates for 4- methylumbelliferone (4-MU) glucuronide and trifluoperazine N-glucuronide using recombinant human UGT isoforms in the absence or presence of cabozantinib. Inhibition kinetic studies were conducted to determine the type of inhibition of cabozantinib on UGTs and the corresponding inhibition constant (Ki) value. In vitro-in vivo extrapolation (IVIVE) was further employed to predict the potential risk of DDI in vivo.

RESULTS

Cabozantinib displayed potent inhibition of UGT1A1, 1A3, 1A4, 1A6, 1A7, 1A8, 1A9, 1A10, 2B7, and 2B15. Cabozantinib exhibited noncompetitive inhibition towards UGT1A1 and 1A3 and inhibition towards UGT1A7 and 1A9. The Ki,u values (mean ± standard deviation) were calculated to be 2.15±0.11 μM, 0.83±0.05 μM, 0.75±0.04 μM and 0.18 ± 0.10 μM for UGT1A1, 1A3, 1A7 and 1A9, respectively. Co-administration of cabozantinib at the clinically approved dose of 60 mg/day or 140 mg/day may result in approximately a 26% to 60% increase in the systemic exposure of drugs predominantly cleared by UGT1A9, implying a high risk of DDIs.

CONCLUSION

Cabozantinib has the potential to cause DDIs via the inhibition of UGT1A9; therefore, additional attention should be paid to the safety of the combined use of cabozantinib and drugs metabolized by UGT1A9.

An Evaluation of Cabozantinib for the Treatment of Renal Cell Carcinoma: Focus on Patient Selection and Perspectives

Cabozantinib is an oral tyrosine kinase inhibitor (TKI) with activity against several receptors involved in the angiogenesis pathway, including vascular endothelial growth factor receptor (VEGFR), c-MET and AXL. The antiangiogenic properties of cabozantinib led to its use as a monotherapy for the treatment of metastatic renal cell cancer (RCC), and quickly resulted in this treatment becoming part of the standard of care for these tumors. Since the advent of immune checkpoint inhibitors (ICIs), new standards of care have emerged in first-line settings, involving dual ICI or ICI-VEGF-TKI (including ICI-cabozantinib) combination treatments, and leading to a more complex algorithm of care. Cabozantinib remains an option in second-line settings and is still a first-line standard of care treatment in cases where the use of ICIs is contraindicated. This review focuses on the selection of patients who may benefit most from cabozantinib therapy, including those with bone and brain metastases and those with a non-clear cell RCC histology. The need to consider disease-related symptoms, comorbidities, age, drug interactions and biomarker analyses in the choice of therapeutic strategy is also highlighted. Finally, the perspectives for the use of cabozantinib in RCC treatment are discussed.

Quantitation of Cabozantinib in Human Plasma by LC-MS/MS

To support a phase III randomized trial of the multi-targeted tyrosine kinase inhibitor cabozantinib in neuroendocrine tumors, we developed a high-performance liquid chromatography mass spectrometry method to quantitate cabozantinib in 50 μL of human plasma. After acetonitrile protein precipitation, chromatographic separation was achieved with a Phenomenex synergy polar reverse phase (4 μm, 2 × 50 mm) column and a gradient of 0.1% formic acid in acetonitrile and 0.1% formic acid in water over a 5-min run time. Detection was performed on a Quattromicro quadrupole mass spectrometer with electrospray, positive-mode ionization. The assay was linear over the concentration range 50-5000 ng/mL and proved to be accurate (103.4-105.4%) and precise (<5.0%CV). Hemolysis (10% RBC) and use of heparin as anticoagulant did not impact quantitation. Recovery from plasma varied between 103.0-107.7% and matrix effect was -47.5 to -41.3%. Plasma freeze-thaw stability (97.7-104.9%), stability for 3 months at -80°C (103.4-111.4%), and stability for 4 h at room temperature (100.1-104.9%) were all acceptable. Incurred sample reanalysis of (N = 64) passed: 100% samples within 20% difference, -0.7% median difference and 1.1% median absolute difference. External validation showed a bias of less than 1.1%. This assay will help further define the clinical pharmacokinetics of cabozantinib.

Simulation-Based Interpretation of Therapeutically Monitored Cabozantinib Plasma Concentration in Advanced Adrenocortical Carcinoma with Hemodialysis

BACKGROUND

Adrenocortical carcinoma is an orphan but aggressive malignancy with limited treatment options. Cabozantinib (CAB), a tyrosine kinase inhibitor, has emerged as a new potential treatment. However, no data are available on whether and how CAB can be administered to patients undergoing hemodialysis.

METHODS

An liquid chromatography with tandem mass spectrometry detection method was developed and validated according to the European Medicines Agency and United States Food and Drug Administration guidelines for bioanalytical method validation. The samples were prepared using protein precipitation and online solid-phase extraction. The method was applied to clinical samples of an adrenocortical carcinoma patient receiving CAB treatment (80 mg daily). During the 10 days of observation, the patient received periodic hemodialysis on 7 days. Pharmacokinetic (PK) simulations were performed using Bayesian forecasting according to an existing population PK model for CAB.

RESULTS

Based on the PK simulation, a mean plasma trough concentration of 1375 ng/mL [90% prediction interval (PI), 601-2602 ng/mL] in the steady state at a daily dose of 80 mg was expected for CAB. However, an individual simulation involving the measured plasma levels of the patient resulted in a mean trough concentration of 348 ng/mL (90% PI, 278-430 ng/mL). The model based on individual PK parameters estimated accessible plasma levels of 521, 625, and 834 ng/mL by dose adjustment to 100, 120, and 160 mg, respectively.

CONCLUSIONS

After establishing an liquid chromatography with tandem mass spectrometry detection method for therapeutic drug monitoring of CAB, our analyses involving a single patient undergoing hemodialysis indicated that higher than expected doses of CAB were required to achieve reasonable plasma concentrations. Our study demonstrates the usefulness of therapeutic drug monitoring for the evaluation of "new" drugs in patients with renal impairment.

An up-to-date evaluation of cabozantinib for the treatment of renal cell carcinoma

Introduction: In the evolving treatment scenario of metastatic renal cell carcinoma, cabozantinib is gaining increasing attention, presenting as a cornerstone therapy, both as a monotherapy and in combination with immune-checkpoint inhibitors.Areas covered: In this review, the authors explore the role of cabozantinib in the treatment of metastatic clear cell and non-clear cell renal cell carcinoma, presenting data from the most recent clinical trials and investigating ongoing studies. They, furthermore, evaluate the pharmacokinetic, pharmacodynamic, and immunomodulatory effect of cabozantinib, as well as underlining the tolerability profile and patients' quality of life.Expert opinion: Cabozantinib's administration as a single agent is restricted to intermediate- and poor-risk patients (according to IMDC criteria). The further advent of anti-VEGF-receptor tyrosine kinase inhibitors combined with immune checkpoint inhibitor regimens (such as pembrolizumab + axitinib) has allowed to expand the use of cabozantinib, leading to its combination with nivolumab. In the next few years, more information is required to look for the application of cabozantinib-based combinations as a later-line approach in metastatic RCC patients, beside their use in the first-line setting.

Model-based comparative analysis of rifampicin and rifabutin drug-drug interaction profile

Rifamycins are widely used for treating mycobacterial and staphylococcal infections. Drug-drug interactions (DDI) caused by rifampicin (RIF) is a major issue. We used a model-based approach to predict the magnitude of DDI with RIF and rifabutin (RBT) for 217 cytochrome P450 (CYP) substrates. On average, DDI caused by low-dose RIF were twice more potent than those caused by RBT. Contrary to RIF, RBT appears unlikely to cause severe DDI, even with sensitive CYP substrates.

Salmon sperm DNA binding study to cabozantinib, a tyrosine kinase inhibitor: Multi-spectroscopic and molecular docking approaches

In the current work, the binding interaction of cabozantinib with salmon sperm DNA (SS-DNA) was studied under simulated physiological conditions (pH 7.4) using fluorescence emission spectroscopy, UV-Vis absorption spectroscopy, viscosity measurement, ionic strength measurement, FT-IR spectroscopy, and molecular modeling methods. The obtained experimental data demonstrated an apparent binding interaction of cabozantinib with SS-DNA. The binding constant (K_b) of cabozantinib with SS-DNA evaluated from the Benesi-Hildebrand plot was equal to 5.79 × 10⁵ at 298 K. The entropy and enthalpy changes (∆S⁰ and ∆H⁰) in the binding interaction of SS-DNA with cabozantinib were 44.13 J mol^-1 K^-1 and -19.72 KJ mol^-1, respectively, demonstrating that the basic binding interaction forces are hydrophobic and hydrogen bonding interactions. Results from UV-Vis absorption spectroscopy, competitive binding interaction with rhodamine B or ethidium bromide, and viscosity measurements revealed that cabozantinib binds to SS-DNA via minor groove binding. The molecular docking results revealed that cabozantinib fits into the AT-rich region of the B-DNA minor groove and the binding site of cabozantinib was 4 base pairs long. Moreover, cabozantinib has eight active torsions, implying a high degree of flexibility in its structure, which played a significant role in the formation of a stable cabozantinib-DNA complex.

Physiologically Based Pharmacokinetic Modelling of Cabozantinib to Simulate Enterohepatic Recirculation, Drug-Drug Interaction with Rifampin and Liver Impairment

Cabozantinib (CAB) is a receptor tyrosine kinase inhibitor approved for the treatment of several cancer types. Enterohepatic recirculation (EHC) of the substance is assumed but has not been further investigated yet. CAB is mainly metabolized via CYP3A4 and is susceptible for drug-drug interactions (DDI). The goal of this work was to develop a physiologically based pharmacokinetic (PBPK) model to investigate EHC, to simulate DDI with Rifampin and to simulate subjects with hepatic impairment. The model was established using PK-Sim^® and six human clinical studies. The inclusion of an EHC process into the model led to the most accurate description of the pharmacokinetic behavior of CAB. The model was able to predict plasma concentrations with low bias and good precision. Ninety-seven percent of all simulated plasma concentrations fell within 2-fold of the corresponding concentration observed. Maximum plasma concentration (C_max) and area under the curve (AUC) were predicted correctly (predicted/observed ratio of 0.9-1.2 for AUC and 0.8-1.1 for C_max). DDI with Rifampin led to a reduction in predicted AUC by 77%. Several physiological parameters were adapted to simulate hepatic impairment correctly. This is the first CAB model used to simulate DDI with Rifampin and hepatic impairment including EHC, which can serve as a starting point for further simulations with regard to special populations.

Thyroid cancer and COVID-19: experience at one single thyroid disease referral center

PURPOSE

Severe acute respiratory syndrome coronavirus 2 (SARS-Cov-2) is challenging health systems all over the world. Cancer patients have a higher risk of being infected by SARS-Cov-2 and higher coronavirus disease 2019 (COVID-19) severity and mortality. Up to date, there were no data about COVID-19 in patients with thyroid cancer (TCs). The aim of the study was to describe the prevalence of COVID-19 in a well-characterized series of TC patients evaluated for the persistence of the neoplastic disease from March to September 2020; as secondary objective, we looked for the COVID-19 disease severity in a subgroup of multimetastatic TC patients.

METHODS

We evaluated 1464 patients affected by persistent TC: 67 patients who were taking multikinase inhibitors (MKIs) and 1397 under active surveillance for a persistent but stable disease. During the clinical evaluation, all patients were specifically investigated about a positive history of Sars-Cov-2 infection.

RESULTS

SARS-Cov-2 infection was identified in 4/1464 (0.3%) cases of patients affected by TC. We identified three cases among patients under active surveillance (0.2%), and one case among patients treated with MKI systemic therapy (1/67, 1.5%). This patient was taking vandetanib for metastatic medullary thyroid cancer (MTC), when he came to our attention referring severe fatigue, dyspnea for light physical activities. He presented a mild COVID-19 and he received exclusively supportive care. After a multidisciplinary consultation, we decided against the discontinuation of vandetanib. After 2 months from the infection, he did not present any signs of active infection, and the MTC metastatic disease was stable.

CONCLUSIONS

We showed that COVID-19 is not more frequent in TC patients than in general population, although a relatively higher prevalence in the group of TC patients treated with MKIs. A single patient with advanced TC and SARS-Cov-2 infection during MKIs treatment had a mild COVID-19 and did not require the discontinuation of MKI therapy. In cases of more severe COVID-19, an accurate evaluation from a multidisciplinary team would consider risks and benefits in taking the decision to continue or stop MKI treatment.

Identification of Enzymes Oxidizing the Tyrosine Kinase Inhibitor Cabozantinib: Cabozantinib Is Predominantly Oxidized by CYP3A4 and Its Oxidation Is Stimulated by cyt b5 Activity

Herein, the in vitro metabolism of tyrosine kinase inhibitor cabozantinib, the drug used for the treatment of metastatic medullary thyroid cancer and advanced renal cell carcinoma, was studied using hepatic microsomal samples of different human donors, human recombinant cytochromes P450 (CYPs), flavin-containing mono-oxygenases (FMOs) and aldehyde oxidase. After incubation with human microsomes, three metabolites, namely cabozantinib N-oxide, desmethyl cabozantinib and monohydroxy cabozantinib, were detected. Significant correlations were found between CYP3A4 activity and generation of all metabolites. The privileged role of CYP3A4 was further confirmed by examining the effect of CYP inhibitors and by human recombinant enzymes. Only four of all tested human recombinant cytochrome P450 were able to oxidize cabozantinib, and CYP3A4 exhibited the most efficient activity. Importantly, cytochrome b₅ (cyt b₅) stimulates the CYP3A4-catalyzed formation of cabozantinib metabolites. In addition, cyt b₅ also stimulates the activity of CYP3A5, whereas two other enzymes, CYP1A1 and 1B1, were not affected by cyt b₅. Since CYP3A4 exhibits high expression in the human liver and was found to be the most efficient enzyme in cabozantinib oxidation, we examined the kinetics of this oxidation. The present study provides substantial insights into the metabolism of cabozantinib and brings novel findings related to cabozantinib pharmacokinetics towards possible utilization in personalized medicine.

Inhibition and induction of CYP enzymes in humans: an update

The cytochrome P450 (CYP) enzyme family is the most important enzyme system catalyzing the phase 1 metabolism of pharmaceuticals and other xenobiotics such as herbal remedies and toxic compounds in the environment. The inhibition and induction of CYPs are major mechanisms causing pharmacokinetic drug–drug interactions. This review presents a comprehensive update on the inhibitors and inducers of the specific CYP enzymes in humans. The focus is on the more recent human in vitro and in vivo findings since the publication of our previous review on this topic in 2008. In addition to the general presentation of inhibitory drugs and inducers of human CYP enzymes by drugs, herbal remedies, and toxic compounds, an in-depth view on tyrosine-kinase inhibitors and antiretroviral HIV medications as victims and perpetrators of drug–drug interactions is provided as examples of the current trends in the field. Also, a concise overview of the mechanisms of CYP induction is presented to aid the understanding of the induction phenomena.

Current Treatment Options for HCC: From Pharmacokinetics to Efficacy and Adverse Events in Liver Cirrhosis

BACKGROUND

Hepatocellular carcinoma (HCC) is among the world's most common cancers. For over ten years, the only medical treatment for it has been the multikinase inhibitor Sorafenib. Currently, however, other first or second-line therapeutic options have also shown efficacy against HCC, such as multikinase inhibitors (Regorafenib, Lenvatinib, and Cabozantinib), a monoclonal antibody against the vascular endothelial growth factor receptor 2 (Ramucirumab), and immune-checkpoint inhibitors (Nivolumab, Pembrolizumab, Ipilimumab).

AIM

The aim of this paper is to review the metabolic pathways of drugs that have been tested for the treatment of HCC and the potential influence of liver failure over those pathways.

METHODS

The Food and Drug Administration (FDA)'s and European Medicines Agency (EMA)'s datasheets, results from clinical trials and observational studies have been reviewed.

RESULTS

This review summarizes the current knowledge regarding targets, metabolic pathways, drug interactions, and adverse events of medical treatments for HCC in cirrhotic patients.

CONCLUSION

The new scenario of systemic HCC therapy includes more active drugs with different metabolic pathways and different liver adverse events. Clinical and pharmacological studies providing more data on the safety of these molecules are urgently needed.

Clinical Pharmacokinetics and Pharmacodynamics of Transarterial Chemoembolization and Targeted Therapies in Hepatocellular Carcinoma

The management of hepatocellular carcinoma (HCC) is based on a multidisciplinary decision tree. Treatment includes loco-regional therapy, mainly transarterial chemoembolization, for intermediate-stage HCC and systemic therapy with oral tyrosine kinase inhibitors (TKIs) for advanced HCC. Transarterial chemoembolization involves hepatic intra-arterial infusion with either conventional procedure or drug-eluting-beads. The aim of the loco-regional procedure is to deliver treatment as close as possible to the tumor both to embolize the tumor area and to enhance efficacy and minimize systemic toxicity of the anticancer drug. Pharmacokinetic studies applied to transarterial chemoembolization are rare and pharmacodynamic studies even rarer. However, all available studies lead to the same conclusions: use of the transarterial route lowers systemic exposure to the cytotoxic drug and leads to much higher tumor drug concentrations than does a similar dose via the intravenous route. However, reproducibility of the procedure remains a major problem, and no consensus exists regarding the choice of anticancer drug and its dosage. Systemic therapy with TKIs is based on sorafenib and lenvatinib as first-line treatment and regorafenib and cabozantinib as second-line treatment. Clinical use of TKIs is challenging because of their complex pharmacokinetics, with high liver metabolism yielding both active metabolites and their common toxicities. Changes in liver function over time with the progression of HCC adds further complexity to the use of TKIs. The challenges posed by TKIs and the HCC disease process means monitoring of TKIs is required to improve clinical management. To date, only partial data supporting sorafenib monitoring is available. Results from further pharmacokinetic/pharmacodynamic studies of these four TKIs are eagerly awaited and are expected to permit such monitoring and the development of consensus guidelines.

Objective Response and Prolonged Disease Control of Advanced Adrenocortical Carcinoma with Cabozantinib

BACKGROUND

Objective response of advanced adrenocortical carcinoma (ACC) to mitotane and cytotoxic chemotherapy regimen is only ~20% and early tumor progression is frequent. Previous clinical trials with oral multikinase inhibitors were negative, which has been attributed in part to inadvertent drug interaction with mitotane. Cabozantinib (CABO) is an inhibitor of c-MET, vascular endothelial growth factor receptor 2, AXL, and RET and approved for advanced kidney cancer, liver carcinoma after previous sorafenib, and medullary thyroid carcinoma.

OBJECTIVE

To investigate the clinical efficacy and safety of CABO monotherapy in ACC patients.

DESIGN

Retrospective cohort study.

SETTING

Three referral centers for ACC (Germany, United States).

RESULTS

Sixteen patients (13 female) with progressive ACC received CABO after previous mitotane in 15/16 and 3 (median, range 0-8) further systemic treatments. Prior CABO therapy, mitotane was discontinued in all patients. Mitotane plasma concentration was <2 mg/L in 7/16 patients and discontinued >12 months in 6 additional patients before CABO use. In 4/5 cases with available plasma samples, CABO concentration was in the expected steady-state range. Adverse events of grade 1/2 and 3 were observed in 13 and 3 patients, respectively, and consistent with the known safety profile of CABO. Best response was partial response in 3, stable disease in 5, and progressive disease in 8 patients. Median progression-free and overall survival was 16 and 58 weeks, respectively.

CONCLUSION

CABO monotherapy appears to be safe and effective as a monotherapy in advanced ACC after failing prior treatments. Therefore, prospective investigation of CABO in ACC patients is warranted.

Management of treatment-related toxicities in advanced medullary thyroid cancer

PURPOSE OF REVIEW

Tyrosine kinase inhibitors (TKI), predominantly vandetanib and cabozantinib, are increasingly used for management of advanced medullary thyroid cancer. This review aims to discuss the major and serious adverse events associated with TKI.

RECENT FINDINGS

The choice of TKI depends on the patient's existing comorbidities. Patients who have long QT interval should avoid vandetanib and those at risk of gastrointestinal perforation should avoid cabozantinib. Hypertension is common during the first 3 months. Treatments include ACE inhibitors, calcium channel blockers (avoiding verapamil and diltiazem, which are CYP3A4 inhibitors), and beta blockers. Diuretics should be second line because of derangement of electrolytes, which may exacerbate QT interval. As nitric oxide (NO) blockade and ET1 are implicated in the mechanism of hypertension, nitrates and endothelin receptor antagonists may be used. Thromboembolism may require anticoagulation or revascularization procedures. Prolonged QT interval should be treated by dose interruption and reduction, correction of electrolytes, and avoidance of medications, which prolong QTc interval. Diarrhoea is managed symptomatically and with electrolyte replacement, dermatological adverse events with avoidance of exacerbating factors and topical therapies. Thyroid function should be monitored.

SUMMARY

Toxicities are common with TKI use, and management involves symptomatic treatment, avoidance of triggers, dose interruption, and dose reduction.

Cabozantinib: A Review in Advanced Hepatocellular Carcinoma

Cabozantinib is an inhibitor of multiple receptor tyrosine kinases (RTKs) with roles in cancer pathogenesis. This review focuses on data relevant to the use of cabozantinib tablets (Cabometyx^®) in the treatment of hepatocellular carcinoma (HCC) in patients who have been previously treated with the multi-RTK inhibitor sorafenib, an indication for which cabozantinib tablets are approved in the EU and USA. Approval of cabozantinib in this setting was based largely on the findings of CELESTIAL, a phase 3 trial in adults with advanced HCC who had previously received sorafenib, had progressive disease after at least one systemic therapy and had received up to two systemic treatments for their advanced disease. Compared with placebo in this study, cabozantinib prolonged both overall survival and progression-free survival, with these findings largely unaffected by patient/disease characteristics. The tolerability profile of cabozantinib in CELESTIAL was acceptable and consistent with that of other multi-RTK inhibitors, with adverse events that were manageable with dose modification and supportive care. Thus, cabozantinib is a welcome additional treatment option for use in adults with HCC previously treated with sorafenib.

Harnessing the therapeutic potential of anticancer drugs through amorphous solid dispersions

The treatment of cancer is still a major challenge. But tremendous progress in anticancer drug discovery and development has occurred in the last few decades. However, this progress has resulted in few effective oncology products due to challenges associated with anticancer drug delivery. Oral administration is the most preferred route for anticancer drug delivery, but the majority of anticancer drugs currently in product pipelines and the majority of those that have been commercially approved have inherently poor water solubility, and this cannot be mitigated without compromising their potency and stability. The poor water solubility of anticancer drugs, in conjunction with other factors, leads to suboptimal pharmacokinetic performance. Thus, these drugs have limited efficacy and safety when administered orally. The amorphous solid dispersion (ASD) is a promising formulation technology that primarily enhances the aqueous solubility of poorly water-soluble drugs. In this review, we discuss the challenges associated with the oral administration of anticancer drugs and the use of ASD technology in alleviating these challenges. We emphasize the ability of ASDs to improve not only the pharmacokinetics of poorly water-soluble anticancer drugs, but also their efficacy and safety. The goal of this paper is to rationalize the application of ASD technology in the formulation of anticancer drugs, thereby creating superior oncology products that lead to improved therapeutic outcomes.

Characterization of Genetic Variation in CYP3A4 on the Metabolism of Cabozantinib in Vitro

Cabozantinib is a multityrosine kinase inhibitor and has a wide range of applications in the clinic, whose metabolism is predominately dependent on CYP3A4. This study was performed to characterize the enzymatic properties of 29 CYP3A4 alleles toward cabozantinib and the functional changes of five selected alleles (the wild-type, CYP3A4.2.8.14 and .15) toward cabozantinib in the presence of ketoconazole. Cabozantinib, 1-100 μM, with/without the presence of ketoconazole and CYP3A4 enzymes in the incubation system went through 30 min incubation at 37 °C, and the concentrations of cabozantinib N-oxide were quantified by UPLC-MS/MS to calculate the corresponding kinetic parameters of each variant. Collectively, without the presence of ketoconazole, most variants displayed defective enzymatic activities in different degrees, and only CYP3A4.14 and .15 showed significantly augmented enzymatic activities. With the presence of ketoconazole, five tested CYP3A4 alleles, even CYP3A4.14 and .15, exhibited obvious reductions in intrinsic clearance. Besides, we compared cabozantinib with regorafenib in relative clearance to confirm that CYP3A4 has the property of substrate specificity. As the first study of CYP3A4 genetic polymorphisms toward cabozantinib, our observations can provide prediction of an individual's capability in response to cabozantinib and guidance for medication and treatment of cabozantinib.

Updated Population Pharmacokinetic Model of Cabozantinib Integrating Various Cancer Types Including Hepatocellular Carcinoma

An integrated population pharmacokinetic (PPK) model was used to evaluate the effects of liver dysfunction on the pharmacokinetics (PK) of cabozantinib in patients with hepatocellular carcinoma and to determine whether clinical dosage adjustment may be necessary in this population. An integrated PPK model previously developed in healthy volunteers and patients with various cancer types was updated with cabozantinib concentration data from hepatocellular carcinoma patients in phase 2 and 3 studies (total 2023; hepatocellular carcinoma 489 patients). Covariate effects of cancer type including hepatocellular carcinoma population and liver dysfunction per the National Cancer Institute Organ Dysfunction Working Group criteria were evaluated (normal 1425; mild liver dysfunction 558; moderate/severe liver dysfunction 15/1 patients). With hepatocellular carcinoma patients, PK parameter estimates and covariate effects were similar to the previous PPK model (2 compartments with first‐ and zero‐order absorption and first‐order elimination). Only medullary thyroid cancer had appreciable PK differences from healthy volunteers. PK parameter estimates were similar with and without addition of liver dysfunction covariates. Patients with mild liver dysfunction were predicted to have minimal differences in apparent clearance of cabozantinib relative to patients with normal liver function. Therefore, no initial cabozantinib dosage adjustment is recommended for cancer patients with mild liver dysfunction. The small sample size for patients with moderate and severe liver dysfunction limited dosing recommendations in these subpopulations. The results from this PPK analysis were different from those of the single‐dose hepatic impairment study in healthy volunteers and more reflective of exposure in cancer patients following daily cabozantinib dosing.

Pharmacogenetic-Based Interactions between Nutraceuticals and Angiogenesis Inhibitors

Background: Angiogenesis inhibitors (AIs) have become established as an effective cancer treatment. Whereas their interactions with antineoplastic drugs have extensively been investigated, little is known of the effect of their co-administration with nutraceuticals/dietary supplements (N/DSs), which are often self-prescribed. N/DSs comprise a wide range of products such as herbs, nutrients, vitamins, minerals, and probiotics. Assessment of their interactions with cancer drugs, particularly AIs, is hampered by the difficulty of gauging the amount of active substances patients actually take. Moreover, there is no agreement on which approach should be used to determine which N/DSs are most likely to influence AI treatment efficacy. We present a comprehensive review of the metabolic routes of the major AIs and their possible interactions with N/DSs. Methods: The PubMed and Cochrane databases were searched for papers describing the metabolic routes of the main AIs and N/DSs. Results: Data from the 133 studies thus identified were used to compile a diagnostic table reporting known and expected AI-N/DS interactions based on their metabolization pathways. AIs and N/DSs sharing the cytochrome P450 pathway are at risk of negative interactions. Conclusions: Recent advances in pharmacogenetics offer exceptional opportunities to identify prognostic and predictive markers to enhance the efficacy of individualized AI treatments. The table provides a guide to genotyping patients who are due to receive AIs and is a promising tool to prevent occult AI-N/DS interactions in poor metabolizers. N/DS use by cancer patients receiving AIs is a topical problem requiring urgent attention from the scientific community.

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.

Belinostat, at Its Clinically Relevant Concentrations, Inhibits Rifampicin-Induced CYP3A4 and MDR1 Gene Expression

Activation of human pregnane X receptor (hPXR) has been associated with induction of chemoresistance. It has been proposed that such chemoresistance via cytochrome P450/drug transporters can be reversed with the use of antagonists that specifically abrogate agonist-mediated hPXR activation. Unfortunately, proposed antagonists lack the specificity and appropriate pharmacological characteristics that allow these features to be active in the clinic. We propose that, ideally, an hPXR antagonist would be a cancer drug itself that is part of a "cancer drug cocktail" and effective as an hPXR antagonist at therapeutic concentrations. Belinostat (BEL), a histone deacetylase inhibitor approved for the treatment of relapsed/refractory peripheral T-cell lymphoma, and often used in combination with chemotherapy, is an attractive candidate based on its hPXR ligand-like features. We sought to determine whether these features of BEL might allow it to behave as an antagonist in combination chemotherapy regimens that include hPXR activators. BEL represses agonist-activated hPXR target gene expression at its therapeutic concentrations in human primary hepatocytes and LS174T human colon cancer cells. BEL repressed rifampicin-induced gene expression of CYP3A4 and multidrug resistance protein 1, as well as their respective protein activities. BEL decreased rifampicin-induced resistance to SN-38, the active metabolite of irinotecan, in LS174T cells. This finding indicates that BEL could suppress hPXR agonist-induced chemoresistance. BEL attenuated the agonist-induced steroid receptor coactivator-1 interaction with hPXR, and, together with molecular docking studies, the study suggests that BEL directly interacts with multiple sites on hPXR. Taken together, our results suggest that BEL, at its clinically relevant therapeutic concentration, can antagonize hPXR agonist-induced gene expression and chemoresistance.

Oral oncolytic and antiretroviral therapy administration: dose adjustments, drug interactions, and other considerations for clinical use

The rise in non-AIDS defining cancers (NADCs) is emerging as a leading cause of death for HIV and cancer patients. To address this, current literature and guidelines suggest the continuation of antiretroviral therapy (ART) with oral oncolytic agents to prevent adverse complications associated with HIV disease progression. However, such an approach has the potential for drug-drug interactions and adverse events for patients on such therapy. Further, recommendations on how to adjust these medications, when used concomitantly, are limited. As such, our purpose is to evaluate existing literature through such means as drug databases (e.g. Micromedex, Lexi-Comp, etc.) and package inserts along with PubMed/Medline, Embase, and Google Scholar databases to develop a reference tool for providers to utilize when there is a decision to treat a patient with ART and oral oncolytic agents concurrently. Our findings suggest that there are many drug interactions that should be taken into consideration with dual therapy. Metabolism is a key determinant of dose adjustment, and many oncolytic agents and ART agents must have their dose adjusted as such. Most notably, several tyrosine kinase inhibitors require dose increases when used with non-nucleoside reverse transcriptase inhibitors (NNRTIs) but must be decreased when used concomitantly with protease inhibitors (PIs) and cobicistat. Further findings suggest that certain agents should not be used together, which include, but are not limited to, such combinations as bosutinib with NNRTIs, cobicistat, or PIs; idelalisib with maraviroc or PIs; neratinib with NNRTIs, cobicistat, or PIs; and venetoclax with NNRTIs. Overall, the most prominent oncolytic drug interactions were discovered when such agents were used concomitantly with PIs, cobicistat-boosted elvitegravir, or NNRTIs. Future studies are necessary to further evaluate the use of these agents together in disease therapy to generate absolute evidence of such findings. However, from the studies evaluated, much evidence exists to suggest that concomitant therapy is not without drug interactions. As such, clinical decisions regarding concomitant therapy should be evaluated in which the risk and benefit of dual therapy are assessed. Dose adjustments must be made accordingly and in consultation with both HIV and oncology clinicians and pharmacists to reduce the risk for adverse outcomes and disease progression for those with cancer and HIV/AIDS.

Clinically relevant drug interactions with multikinase inhibitors: a review

Multikinase inhibitors (MKIs), including the tyrosine kinase inhibitors (TKIs), have rapidly become an established factor in daily (hemato)-oncology practice. Although the oral route of administration offers improved flexibility and convenience for the patient, challenges arise in the use of MKIs. As MKIs are prescribed extensively, patients are at increased risk for (severe) drug–drug interactions (DDIs). As a result of these DDIs, plasma pharmacokinetics of MKIs may vary significantly, thereby leading to high interpatient variability and subsequent risk for increased toxicity or a diminished therapeutic outcome. Most clinically relevant DDIs with MKIs concern altered absorption and metabolism. The absorption of MKIs may be decreased by concomitant use of gastric acid-suppressive agents (e.g. proton pump inhibitors) as many kinase inhibitors show pH-dependent solubility. In addition, DDIs concerning drug (uptake and efflux) transporters may be of significant clinical relevance during MKI therapy. Furthermore, since many MKIs are substrates for cytochrome P450 isoenzymes (CYPs), induction or inhibition with strong CYP inhibitors or inducers may lead to significant alterations in MKI exposure. In conclusion, DDIs are of major concern during MKI therapy and need to be monitored closely in clinical practice. Based on the current knowledge and available literature, practical recommendations for management of these DDIs in clinical practice are presented in this review.

Pazopanib, Cabozantinib, and Vandetanib in the Treatment of Progressive Medullary Thyroid Cancer with a Special Focus on the Adverse Effects on Hypertension

Medullary thyroid cancer (MTC) is a rare malignancy with a poor prognosis. First line therapy is surgery, which is the only curative method of the disease. However, in non-operable cases or with tumor progression and metastases, a systemic treatment is necessary. This form of cancer is often insensitive to conventional chemotherapy, but the use of tyrosine kinase inhibitors (TKIs), such as pazopanib, cabozantinib, and vandetanib, has shown promising results with an increase in progression-free survival and prolonged lifetime. Therefore, we focused on the pharmacological characteristics of TKIs, their mechanism of action, their application as a secondary treatment option for MTC, their efficacy as a cancer drug treatment, and reviewed the ongoing clinical trials. TKIs also act systemically causing various adverse events (AEs). One common AE of this treatment is hypertension, known to be associated with cardiovascular disease and can therefore potentially worsen the well-being of the treated patients. The available treatment strategies of drug-induced hypertension were discussed. The mechanism behind the development of hypertension is still unclear. Therefore, the treatment of this AE remains symptomatic. Thus, future studies are necessary to investigate the link between tumor growth inhibition and hypertension. In addition, optimized, individual treatment strategies should be implemented.

Cabozantinib for the Management of Metastatic Clear Cell Renal Cell Carcinoma

Cabozantinib is a multi-tyrosine kinase inhibitor used for the treatment of various solid-organ tumours. It was recently approved as a first- and second-line therapeutic for the management of advanced/metastatic renal cell carcinoma based on the results of two randomised controlled trials. The phase III METEOR trial compared cabozantinib against everolimus as a second- or greater line therapy and found benefits in progression-free and overall survival, and the phase II CABOSUN trial compared cabozantinib against sunitinib as a first-line therapeutic and found benefits in terms of progression-free survival. This review briefly summarises how cabozantinib fits into current treatment paradigms for the management of advanced renal cell carcinoma.

Cabozantinib as first-line treatment in advanced renal cell carcinoma: a profile of its use

Oral cabozantinib tablets (Cabometyx^®) are an important option for the treatment of advanced renal cell carcinoma (RCC). Cabozantinib is an anti-angiogenic agent and potently inhibits multiple tyrosine kinases, including those implicated in the development of RCC. The previously approved indication of cabozantinib tablets (i.e. treatment of advanced RCC following prior VEGF-targeted therapy) has been extended to include the first-line treatment of advanced RCC in treatment-naïve adults with intermediate or poor risk (EU) and all patients with advanced RCC (USA). These label extensions are based on the results of a randomized, open-label phase 2 trial, in which adults with metastatic RCC of poor or intermediate risk received targeted first-line treatment with cabozantinib or standard-of-care sunitinib. Relative to sunitinib, cabozantinib significantly prolonged median progression-free survival (primary endpoint; investigator and independent assessments), and increased the objective response rate (investigator assessment). The tolerability profile of cabozantinib is comparable to those of other tyrosine kinase inhibitors, with adverse events being manageable with medical intervention, dosage reductions, treatment interruption and/or permanent discontinuation.

Metabolic profiling of the anti-tumor drug regorafenib in mice

Regorafenib is a novel tyrosine kinase inhibitor, which has been approved by the United States Food and Drug Administration for the treatment of various tumors. The purpose of the present study was to describe the metabolic map of regorafenib, and investigate its effect on liver function. Mass spectrometry-based metabolomics approach integrated with multiple mass defect filter was used to determine the metabolites of regorafenib in vitro incubation mixtures (human liver microsomes and mouse liver microsomes), serum, urine and feces samples from mice treated with 80 mg/kg regorafenib. Eleven metabolites including four novel metabolites were identified in the present investigation. As halogen substituted drug, reductive defluorination and oxidative dechlorination metabolites of regorafenib were firstly report in present study. By screening using recombinant cytochrome P450 s (CYPs), CYP3A4 was found to be the principal isoforms involved in regorafenib metabolism. The predication with a molecular docking model confirmed that regorafenib had potential to interact with the active sites of CYP3A4, CYP3A5 and CYP2D6. Serum chemistry analysis revealed no evidence of hepatic damage from regorafenib exposure. This study provided a global view of regorafenib metabolism and its potential side-effects.

A dose finding clinical trial of cabozantinib (XL184) administered in combination with abiraterone acetate in metastatic castration-resistant prostate cancer

BACKGROUND

Cabozantinib can enhance the effect of abiraterone in preclinical prostate cancer models. This study aimed to define the recommended phase 2 dose (RP2D) and preliminary efficacy of abiraterone + cabozantinib in mCRPC.

METHODS

Patients with progressive mCRPC with 0-2 prior chemotherapy regimens but no prior CYP17A1 or MET inhibitor received abiraterone acetate at 1000 mg daily with prednisone 5 mg BID in combination with cabozantinib at 20, 40, or 60 mg daily in a dose-escalation 3 + 3 open-label phase 1 design (Part A). After tolerable doses were defined, cohorts were expanded to better define toxicity and efficacy (Part B).

RESULTS

There were no dose-limiting toxicities (DLTs) in the first 4 weeks at any of the three dose levels in Part A. Two of the three patients at the 60 mg dose level required dose reductions beyond cycle 2 due to fatigue. In Part B, nine more patients were accrued to each of the 20 and 40 mg doses. Of the 12 patients treated at the 40 mg dose, only one DLT (grade 3 Lipase elevation) was observed in cycle 1. The median time to radiographic progression was 12.88 months (95% CI:5.42- not estimated [NE]) in the 20 mg cohort and 22.01 months (95% CI:15.44-NE) in the 40 mg cohort. Median overall survival was 23.29 months (95% CI:19.06-NE) in the 20 mg cohort and 39.08 months (95% CI:17.38-NE) in the 40 mg cohort.

CONCLUSIONS

Based on tolerability and preliminary efficacy, 40 mg cabozantinib plus 1000 mg abiraterone daily is the RP2D.

A population pharmacokinetic model of cabozantinib in healthy volunteers and patients with various cancer types

Purpose

An integrated population pharmacokinetic (popPK) model was developed to describe the pharmacokinetics (PK) of tyrosine kinase inhibitor cabozantinib in healthy volunteers (HVs) and patients with various cancer types and to identify any differences in cabozantinib PK across these populations.

Methods

Plasma concentration data used to develop the popPK model were obtained from nine clinical trials (8072 concentrations from 1534 HVs or patients) of cabozantinib in HVs and patients with renal cell carcinoma (RCC), medullary thyroid carcinoma (MTC), glioblastoma multiforme, castration-resistant prostate cancer, or other advanced malignancies.

Results

PK data across studies were adequately characterized by a two-compartment disposition model with dual first- and zero-order absorption processes and first-order elimination. Baseline demographic covariates (age, weight, gender, race, and cancer type) were generally predicted to have a small-to-moderate impact on apparent clearance (CL/F). However, MTC cancer type did show an approximately 93% higher CL/F relative to HVs following chronic dosing, resulting in approximately 40–50% lower predicted steady-state cabozantinib plasma concentrations.

Conclusion

This popPK analysis showed cabozantinib CL/F values to be higher for patients with MTC and may account for the higher dosage required in this patient population (140-mg) to achieve plasma exposures comparable to those in patients with RCC and other tumor types administered a 60-mg cabozantinib tablet dose. Possible factors that may underlie the higher cabozantinib clearance observed in MTC patients are discussed.

Electronic supplementary material

The online version of this article (10.1007/s00280-018-3581-0) contains supplementary material, which is available to authorized users.

Management of Adverse Events Associated with Cabozantinib Therapy in Renal Cell Carcinoma

Cabozantinib was recently approved for the treatment of advanced renal cell carcinoma (RCC) after treatment with vascular endothelial growth factor (VEGF)-targeted therapy. Cabozantinib is a multikinase inhibitor targeting VEGF receptor (VEGFR) 2, mesenchymal-epithelial transition receptor, and "anexelekto" receptor tyrosine kinase. A 60-mg daily dose led to improved overall survival and progression-free survival (PFS) versus everolimus in advanced RCC patients as a second- or later-line treatment in the METEOR trial. Improved PFS with cabozantinib versus sunitinib has also been demonstrated in the first-line setting in CABOSUN. However, cabozantinib, like other VEGFR inhibitors, is associated with toxicity that may affect the patient's quality of life. The most frequent adverse events (AEs) are diarrhea, fatigue, hypertension, hand-foot syndrome, weight loss, nausea, and stomatitis. This article summarizes the safety profile of cabozantinib in RCC patients and offers guidance for the management of these AEs. We discuss the underlying mechanisms of these AEs and, based on our experiences with cabozantinib and other multikinase inhibitors, we present approaches to manage toxicity. Prophylactic and therapeutic solutions are available to help with the management of toxicity associated with cabozantinib, and adequate interventions can ensure optimum adherence and maximize patient outcomes.

IMPLICATIONS FOR PRACTICE

Cabozantinib leads to improved survival outcomes in renal cell carcinoma patients compared with everolimus. However, management of the adverse event profile is crucial to achieve optimum adherence and outcomes with the use of cabozantinib. This review aims to provide appropriate guidance that will minimize the impact of adverse events and help to maximize the utility of this agent in patients with advanced renal cell carcinoma.

Cabozantinib in the treatment of advanced renal cell carcinoma in adults following prior vascular endothelial growth factor targeted therapy: clinical trial evidence and experience

Cabozantinib is an oral multitargeted tyrosine kinase inhibitor (TKI) that potently inhibits MET and AXL, both associated with poor prognosis in renal cell carcinoma (RCC), next to vascular endothelial growth factor receptor 2, KIT, FLT3 and RET. Chronic treatment with vascular endothelial growth factor receptor (VEGFR)-targeting sunitinib upregulates MET and AXL in RCC, indicating that cabozantinib may be particularly effective in patients with advanced RCC whose disease progressed on prior VEGFR-targeted treatment. Cabozantinib (60 mg once daily) has been investigated in comparison to everolimus (10 mg once daily) in a phase III randomized controlled trial (RCT) in 658 patients with advanced RCC of whom 71% had received one prior and 29% had received at least two prior lines of VEGR-targeted therapy. This study demonstrated highly significant improved progression-free survival of 7.4 months versus 3.9 months with a hazard ratio (HR) of 0.51 [95% confidence interval (CI) 0.41-0.62] in favour of cabozantinib. Cabozantinib also showed a superior overall survival of 21.4 months versus 16.5 months (HR 0.66; 95% CI 0.53-0.83). Objective response rate was higher in cabozantinib-treated patients, 17% versus 3%. Clinical benefit was shown in all subgroups of patients, including in patients with bone or visceral metastases. The safety profile was acceptable with manageable side effects. Based on this study, cabozantinib is a highly effective approved second-line treatment option for patients with advanced RCC with a manageable toxicity profile. Other recently approved second-line agents include checkpoint inhibitor nivolumab and VEGF-targeting agent lenvatinib combined with everolimus. In the absence of predictive markers as well as head-to-head comparisons of these three recently approved treatments, the choice between these drugs in second-line treatment will probably be made based on comorbidities, tolerability of previous treatment and presence of high tumour burden with rapidly progressive disease. Future pretreatment assessment of MET and AXL tumour aberration may aid clinicians to make a rational choice between currently approved second-line treatment options.

Clinical Pharmacokinetics and Pharmacodynamics of Cabozantinib

Cabozantinib inhibits receptor tyrosine kinases involved in tumor angiogenesis and metastasis. The capsule formulation (Cometriq^®) is approved for the treatment of progressive metastatic medullary thyroid cancer at a 140-mg free base equivalent dose. The tablet formulation (Cabometyx™, 60-mg free base equivalent dose) is approved for the treatment of renal cell carcinoma following anti-angiogenic therapy. Cabozantinib displays a long terminal plasma half-life (~120 h) and accumulates ~fivefold by day 15 following daily dosing based on area under the plasma concentration-time curve (AUC). Four identified inactive metabolites constitute >65 % of total cabozantinib-related AUC following a single 140-mg free base equivalent dose. Cabozantinib AUC was increased by 63-81 % or 7-30 % in subjects with mild/moderate hepatic or renal impairment, respectively; by 34-38 % with concomitant cytochrome P450 3A4 inhibitor ketoconazole; and by 57 % following a high-fat meal. Cabozantinib AUC was decreased by 76-77 % with concomitant cytochrome P450 3A4 inducer rifampin, and was unaffected following administration of proton pump inhibitor esomeprazole. Cabozantinib is a potent in vitro inhibitor of P-glycoprotein, and multidrug and toxin extrusion transporter 1 and 2-K, and is a substrate for multidrug resistance protein 2. No clinically significant covariates affecting cabozantinib pharmacokinetics were identified in a population pharmacokinetic analysis. Patients with medullary thyroid cancer with low model-predicted apparent clearance were more likely to dose hold/reduce cabozantinib early, and had a lower average dose through day 85. However, longitudinal tumor modeling suggests that cabozantinib dose reductions from 140 to 60 mg/day did not markedly reduce tumor growth inhibition in medullary thyroid cancer patients.

Pharmacokinetic/Pharmacodynamic Modeling of Schedule-Dependent Interaction between Docetaxel and Cabozantinib in Human Prostate Cancer Xenograft Models

In this work, a semimechanistic pharmacokinetic/pharmacodynamic (PK/PD) model to quantitatively describe the antitumor activity of docetaxel (Doc) and cabozantinib (Cab) under monotherapy, concurrent therapy, interval therapy, and different sequential therapy in mouse xenograft models of castration-resistant prostate cancer was developed and evaluated. The pharmacokinetics (PK) of Doc and Cab when administered separately and simultaneously were investigated in nude mice, and PD study was conducted in tumor-bearing mice treated with different dosing schedules. The PK interaction between Doc and Cab was expressed by adding the effect of Cab on the clearance of Doc in the PK model. And the PD interaction between the two drugs was demonstrated by the developed PK/PD model through the combination index "φ" Our results showed that the concurrent therapy and Doc followed by Cab (Doc ∼ Cab) sequential therapy exhibited better tumor inhibitory efficacy than monotherapy. The Cab followed by Doc (Cab ∼ Doc) sequential schedule was less effective than monotherapy, and the interval therapy did not enhance the antitumor efficacy compared with the concurrent therapy. The parameter φ estimated from the PK/PD model quantitatively characterized the action between Doc and Cab. There was no significant PD interaction between Doc and Cab in both the concurrent schedule and the interval schedule, whereas the effect of the two drugs in the "Doc ∼ Cab" and "Cab ∼ Doc" sequential schedule was synergistic and antagonistic, respectively. The proposed model properly described the antitumor effects of Doc and Cab under different treatment schedules and could be used for dose optimization through model-based simulation.

Cabozantinib in the treatment of hepatocellular carcinoma

Despite clinical studies with different mechanisms of action, no new systemic therapies were approved for hepatocellular carcinoma (HCC) between sorafenib in 2007 and regorafenib in 2017. This is an area of interest to improve outcomes and quality of life. Cabozantinib is oral, small-molecule tyrosine kinase inhibitor that primarily targets MET, VEGFR2, AXL and RET, with additional effect on KIT and FLT3. Cabozantinib is approved for progressive metastatic medullary thyroid cancer and previously treated renal cell carcinoma, and is in development for multiple solid tumors. Given positive results from a Phase II study, cabozantinib is under evaluation in a Phase III randomized controlled trial for patients with advanced HCC previously treated with sorafenib. It has been granted orphan drug status in the USA for this indication. This review summarizes the development of cabozantinib in HCC.

Medullary thyroid carcinoma - Adverse events during systemic treatment: risk-benefit ratio

Medullary thyroid carcinoma (MTC) is a rare neuroendocrine tumor originating from parafollicular C cells of the thyroid and associated with mutations in the proto-oncogene REarranged during Transfection (RET). The prognosis of MTC depends on clinical stage, with a 95.6% 10-year survival rate among patients with localized disease and 40% among patients with advanced disease. Standard chemotherapy and radiotherapy have no significant impact on the overall survival of these patients and two tyrosine kinase receptor inhibitors (TKIs), vandetanib and cabozantinib, have been recently approved for the systemic treatment of locally advanced or metastatic MTC. However, since patients with MTC and residual or recurrent disease may have an indolent course with no need for systemic treatment, and since these drugs are highly toxic, it is extremely important to select the patients who will receive these drugs in a correct manner. It is also essential to carefully monitor patients using TKI regarding possible adverse effects, which should be properly managed when occurring.