Exposure-response modeling of cabozantinib in patients with renal cell carcinoma: Implications for patient care

Safety of solid oncology drugs in older patients: a narrative review

The older population represents ∼50%-60% of the population of newly diagnosed patients with cancer. Due to physiological and pathological aging and the increased presence of comorbidities and frailty factors, this population is at higher risk of serious toxicity from anticancer drugs and, consequently, often under-treated. Despite the complexity of these treatments, a good knowledge of the pharmacology of anticancer drugs and potentially risky situations can limit the emergence of potentially lethal toxicities in this population. This review focuses on optimizing systemic oncology treatments for older patients, emphasizing the unique characteristics of each therapeutic class and the necessity for a precautionary approach for this vulnerable population.

Real world data of cabozantinib in patients with hepatocellular carcinoma: Focusing on dose setting and modification

AIM

To investigate the outcomes of cabozantinib in patients with unresectable hepatocellular carcinoma (uHCC), focusing on dose setting and modification.

METHODS

We retrospectively analyzed 34 Japanese patients who received cabozantinib for uHCC. Trough concentrations (Ctrough) of cabozantinib were also measured weekly for 6 weeks in the 18 patients.

RESULTS

Sixteen patients received ≥40 mg (high-dose group), and 18 patients received 20 mg (low-dose group). Dose escalations were performed in 27.8% of the patients in the low-dose group. Although median duration of the first dose reduction or interruption in the low-dose group was twice that in the high-dose group (28 vs. 14 days, p < 0.001), there were no significant differences in the relative dose intensity (RDI) during 6 weeks, progression free survival (PFS), and overall survival (p = 0.162, p = 0.950, p = 0.817, respectively) between the two groups. Patients who received RDI during 6 weeks ≥33.4% showed a trend toward longer median PFS (p = 0.054). Each serum aldolase value during the 6 weeks was significantly correlated with the Ctrough at any point (r = 0.500, p < 0.001). In multivariate analyses, aldolase ≥8.7 U/L within 2 weeks was significantly associated with the very early dose reduction or interruption (odds ratio 20.0, p = 0.002).

CONCLUSIONS

An initial dose of 20 mg cabozantinib could be a safe option in Japanese patients. The serum aldolase value could be useful for making appropriate dose modifications of cabozantinib.

Population Pharmacokinetics of Cabozantinib in Metastatic Renal Cell Carcinoma Patients: Towards Drug Expenses Saving Regimens

INTRODUCTION

Cabozantinib is one of the preferred treatment options in the latest metastatic renal cell carcinoma (mRCC) guidelines. Cabozantinib is also associated with high drug expenses irrespective of the used dose, because a flat-prizing model has been implemented. In addition, concomitant intake with a high-fat meal increases its bioavailability on average by 57%. Combined with the long terminal half-life of cabozantinib (99 h), this creates possibilities to extend the dosing interval to reduce drug expenses whilst maintaining equivalent exposure.

OBJECTIVES

The primary objective was to evaluate the population pharmacokinetic (POPPK) model of cabozantinib developed for its registration using real-world patients' therapeutic drug monitoring (TDM) data. The secondary objective was to design, simulate, and evaluate alternative dose regimens with the aim to reduce drug expenses whilst maintaining comparable exposure.

METHODS

Retrospective TDM data from mRCC patients treated with cabozantinib were obtained. The data were evaluated using the published Food and Drug Administration (FDA) cabozantinib POPPK model, a two-compartment disposition model with a dual (fast and slow) lagged first-order absorption process derived from FDA registration documents, as a basis. Subsequently, simulations of alternative drug expenses saving regimens were evaluated.

RESULTS

Twenty-seven mRCC patients with 75 pharmacokinetic observations were included. Patients were treated for a median of 75 days with a median dose of 40 mg. Model evaluation results showed that the cabozantinib TDM concentrations were adequately predicted by the published FDA cabozantinib POPPK model, except for a slightly higher clearance (CL) of 3.11 L/h compared to the reported value (2.23 L/h). The simulation study indicated that an alternative dose regimen that consists of taking 60 mg of cabozantinib for 2 days and then skipping 1 day results in comparable average exposure when compared with a 40 mg daily dose, both without food interaction, while saving 33.3% of the total drug expenses per month. The food effect of a high-fat meal was also taken into account when simulating other alternative dose regimens; 40 mg every 72 h combined with a high-fat meal resulted in comparable exposure when compared with a 20 mg daily dose fasted, while saving 66.7% in drug expenses.

CONCLUSIONS

In this study, the optimized cabozantinib POPPK model resulted in adequate prediction of real-world cabozantinib pharmacokinetic data. Alternative dosing regimens with and without using known food interactions were proposed that resulted in potential strategies to significantly reduce cabozantinib drug expenses.

Exposure-response relationship of cabozantinib in patients with metastatic renal cell carcinoma treated in routine care

BACKGROUND

Interindividual pharmacokinetic variability may influence the clinical benefit or toxicity of cabozantinib in metastatic renal cell carcinoma (mRCC). We aimed to investigate the exposure-toxicity and exposure-response relationship of cabozantinib in unselected mRCC patients treated in routine care.

METHODS

This ambispective multicenter study enrolled consecutive patients receiving cabozantinib in monotherapy. Steady-state trough concentration (Cmin,ss) within the first 3 months after treatment initiation was used for the PK/PD analysis with dose-limiting toxicity (DLT) and survival outcomes. Logistic regression and Cox proportional-hazards models were used to identify the risk factors of DLT and inefficacy in patients, respectively.

RESULTS

Seventy-eight mRCC patients were eligible for the statistical analysis. Fifty-two patients (67%) experienced DLT with a median onset of 2.1 months (95%CI 0.7-8.2). In multivariate analysis, Cmin,ss was identified as an independent risk factor of DLT (OR 1.46, 95%CI [1.04-2.04]; p = 0.029). PFS and OS were not statistically associated with the starting dose (p = 0.81 and p = 0.98, respectively). In the multivariate analysis of PFS, Cmin, ss > 336 ng/mL resulted in a hazard ratio of 0.28 (95%CI, 0.10-0.77, p = 0.014). By contrast, Cmin, ss > 336 ng/mL was not statistically associated with longer OS.

CONCLUSION

Early plasma drug monitoring may be useful to optimise cabozantinib treatment in mRCC patients treated in monotherapy, especially in frail patients starting at a lower than standard dose.

Association of Cabozantinib Dose Reductions for Toxicity With Clinical Effectiveness in Metastatic Renal Cell Carcinoma (mRCC): Results From the Canadian Kidney Cancer Information System (CKCis)

BACKGROUND

Cabozantinib, an oral multi-targeted tyrosine kinase inhibitor (TKI), has demonstrated efficacy in metastatic renal cell carcinoma (mRCC). The association between toxicity and therapeutic effectiveness has been established with other TKIs. We investigated whether cabozantinib dose reductions, a surrogate for toxicity and adequate drug exposure, were associated with improved clinical outcomes in mRCC.

METHODS

Employing the CKCis database, we analyzed patients treated with cabozantinib in the second line or later between 2011 to 2021. The cohort was stratified into those needing dose reductions (DR) during treatment and those not (no-DR). Outcomes, including objective response rate (ORR), time to treatment failure (TTF), and overall survival (OS), were compared based on dose reduction status. The influence of the initial dose on outcomes was also explored.

RESULTS

Among 319 cabozantinib-treated patients, 48.3% underwent dose reductions. Response rates exhibited no significant difference between the DR and no-DR groups (15.1% vs. 18.2%, P = .55). Patients with DR had superior median OS (26.15 vs. 15.47 months, P = .019) and TTF (12.74 vs. 6.44 months, P = .022) compared to no-DR patients. These differences retained significance following adjustment for IMDC risk group (OS HR = 0.67, P = .032; TTF HR = 0.65, P = .008). There was no association between the initial dose and ORR, OS, or TTF.

CONCLUSION

This study highlights the link between cabozantinib dose reductions due to toxicity and improved survival and time to treatment failure in mRCC patients. These findings underscore the potential of using on-treatment toxicity as an indicator of adequate drug exposure to individualize dosing and optimize treatment effectiveness. Larger studies are warranted to validate these results and develop individualized strategies for cabozantinib when given alone or in combination with immunotherapy.

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.

Tailoring treatment with cabozantinib or pazopanib in patients with metastatic renal cell carcinoma: does it affect outcome?

BACKGROUND

Metastatic renal cell carcinoma (mRCC) treatment is still largely based on TKI use. Treatment adjustment due to toxicities is often needed. The aim of the present study was to determine the impact of treatment modifications on the outcome of mRCC patients treated with cabozantinib or pazopanib.

RESEARCH DESIGN AND METHODS

This retrospective multicenter study enrolled consecutive patients receiving cabozantinib or pazopanib between January 2012 and December 2020. We evaluated the correlation of TKI treatment modifications with grade 3-4 toxicities and progression-free (PFS) and overall survival (OS). We also performed a landmark analysis excluding patients who did not undergo at least 5 months of therapy.

RESULTS

Among 301 patients, 179 (59%) were treated with pazopanib, 122 (41%) with cabozantinib. Treatment modifications were related to grade 3-4 toxicities (p < 0.0001). We observed a statistically significant longer PFS and OS in patients who underwent dose reductions (p < 0.0001 for both PFS and OS), temporary interruption (p < 0.0001 for both PFS and OS) and schedule modifications (p = 0.007 for PFS and p = 0.012 for OS) at univariate analysis. These results were confirmed at multivariable and landmark analyses.

CONCLUSIONS

Tailoring treatment with pazopanib and cabozantinib was associated with better PFS/OS.

Cabozantinib exposure-response analysis for the phase 3 CheckMate 9ER trial of nivolumab plus cabozantinib versus sunitinib in first-line advanced renal cell carcinoma

PURPOSE

In the phase 3 CheckMate 9ER trial, intravenous nivolumab (240 mg every 2 weeks) plus oral cabozantinib (40 mg/day) improved progression-free survival (PFS) versus sunitinib as first-line therapy for advanced renal cell carcinoma (RCC). To support cabozantinib dosing with the combination, this exposure-response analysis characterized the relationship of cabozantinib exposure with clinical endpoints.

METHODS

Dose modification was allowed with cabozantinib (holds and reductions) to manage adverse events (AEs). The population pharmacokinetics analysis was updated and used to generate individual predicted cabozantinib exposure measures. Kaplan-Meier plots and time-to-event Cox proportional hazard (CPH) exposure-response models characterized the relationship of cabozantinib exposure with PFS, dose modifications, and selected AEs.

RESULTS

Kaplan-Meier plots showed no clear difference in PFS across cabozantinib exposure quartiles. Cabozantinib exposure did not significantly affect the hazard of PFS in the CPH base model nor in the final model. In contrast, baseline albumin and nivolumab clearance had a significant effect on PFS. There was no significant relationship between cabozantinib clearance and risk of dose modification, but a significant relationship was identified between cabozantinib exposure and Grade ≥ 1 palmar-plantar-erythrodysesthesia and Grade ≥ 3 diarrhea in the exposure-response analysis.

CONCLUSION

To optimize individual cabozantinib exposure, these data support the dose modification strategies in CheckMate 9ER for cabozantinib in patients with advanced RCC when combined with nivolumab.

Comparison of a newly developed high performance liquid chromatography method with diode array detection to a liquid chromatography tandem mass spectrometry method for the quantification of cabozantinib, dabrafenib, nilotinib and osimertinib in human serum - Application to therapeutic drug monitoring

OBJECTIVE

Liquid chromatography tandem mass spectrometry (LC-MS/MS) is a highly selective and sensitive method for the quantification of kinase inhibitors, yet not widely available in clinical routine for therapeutic drug monitoring (TDM). To provide a more accessible alternative, a high-performance liquid chromatography method with ultraviolet/diode array detection (HPLC-UV/DAD) to quantify cabozantinib, dabrafenib, nilotinib and osimertinib, was developed and validated. Results were compared to LC-MS/MS.

METHOD

After liquid-liquid-extraction and reconstitution of the residue in 20 mM potassium dihydrogen phosphate (KH2PO4) (pH4.6), acetonitrile and methanol (50:25:25,v/v/v), chromatographic separation was achieved in 20.0 min using a Luna® C18(2)-HST column (100 × 2 mm, 2.5 μm), protected by a C18 guard column (4 × 2 mm) (column temperature: 30 °C, autosampler: 10 °C). Mobile phase A and B consisted of 20 mM KH2PO4 (pH4.9) and acetonitrile (9:1,v/v) and acetonitrile:20 mM KH2PO4 (pH4.9) (7:3,v/v), respectively. Gradient elution was performed at 200 µL/min. Analytes were quantified at 250, 280 and 330 nm, using sorafenib as internal standard.

RESULTS

Calibration curves were linear (35-2,000 ng/mL). Method validation assays met requirements by U.S. Food and Drug Administration and European Medicines Agency. Compared to the more sensitive and specific LC-MS/MS, HPLC-UV/DAD showed a good correlation and a strong positive association (Kendall's tau 0.811¬-0.963, p < 0.05). Bland-Altman-plots revealed 100% (cabozantinib), 98.6% (dabrafenib), 98.6% (nilotinib) and 96.2% (osimertinib) of relative differences inside the limits of agreement. Regulatory agency criteria for sample reanalysis and cross validation were met (±20%-criterion:100% (cabozantinib), 94.3% (dabrafenib), 92% (nilotinib) and 84.6% (osimertinib).

CONCLUSION

The developed HPLC-UV/DAD method is "fit-for-TDM" in clinical routine and serves as a genuine alternative to LC-MS/MS.

Extended disease control with unconventional cabozantinib dose increase in metastatic renal cell carcinoma

Background

Cabozantinib is among the most potent tyrosine kinase inhibitors (TKIs) FDA-approved for metastatic renal cell carcinoma (mRCC). Effective treatments after progression on cabozantinib salvage therapy are limited. Dose escalation for other TKIs has been shown to afford added disease control.

Objective

We sought to evaluate whether dose escalation of cabozantinib (Cabometyx®) from conventional doses in select patients with limited treatment options offered additional disease control. We asked how cabozantinib dose increases may affect circulating drug levels.

Methods

We identified patients with mRCC at the University of Texas Southwestern Medical Center who were treated with cabozantinib dose escalation to 80 mg after progressing on conventional cabozantinib 60 mg. We then queried leading kidney cancer investigators across the world to identify additional patients. Finally, we reviewed pharmacokinetic (PK) data to assess how higher doses impacted circulating levels by comparison to other formulations (Cometriq® capsules).

Results

We report six patients treated at two different institutions with cabozantinib-responsive disease and good tolerability, where cabozantinib was dose escalated (typically to 80 mg, but as high as 120 mg) after progression on 60 mg, a strategy that resulted in added disease control (median duration, 14 months; 95% Confidence Interval [CI]: 8 - Not Estimable[NE]). Four patients (66.7%) had disease control lasting at least 1 year. No grade III/IV adverse events were identified in this small, select, cohort. A comparison of PK data to FDA-approved cabozantinib 140 mg capsules suggest that cabozantinib 80 mg tablets results in comparable exposures.

Conclusions

mRCC patients with cabozantinib responsive disease and reasonable tolerability may benefit from dose escalation at progression.

Association of cabozantinib pharmacokinetics, progression and toxicity in metastatic renal cell carcinoma patients: results from a pharmacokinetics/pharmacodynamics study

Background

Cabozantinib is a tyrosine kinase inhibitor with a substantial efficacy in metastatic renal cell carcinoma, and is associated with a challenging toxicity profile leading to frequent drug discontinuations. Whereas an exposure/safety relationship was demonstrated for this drug, an exposure/efficacy relationship is still unknown.

Patients and methods

We carried out a monocentric, observational, pharmacokinetics/pharmacodynamics (PK/PD) study in patients with metastatic renal cell carcinoma (INDS MR 5612140520). We used measured blood concentrations of cabozantinib (C_meas) to determine the area under the curve (AUC), apparent clearance (Cl/F) and residual blood concentration (C_trough). Best overall response according to RECIST 1.1 and relevant toxicity (adverse event grade 3-4 or grade 2 requiring dose reduction or discontinuation) were assessed according to C_meas, C_trough, AUC and Cl/F.

Results

We enrolled 76 patients, including 35 who experienced disease progression and 30 with grade 3-4 toxicity. Patients with progressive disease had a significantly lower median C_trough (406 versus 634 ng/ml, P = 0.001), Cl/F (2 versus 2.9 l/h, P = 0.002) and AUC (16 versus 20 μg h/ml, P = 0.037) compared with patients who had disease control as best response. Patients with relevant toxicity had a significantly higher C_meas (732 versus 531 ng/ml, P = 0.006), C_trough (693 versus 521 ng/ml, P = 0.005) and AUC (21 versus 16 μg h/ml, P = 0.046) compared with patients who did not experience any grade relevant toxicity. Receiver operating characteristic curves obtained from our study defined a threshold for drug efficacy of 536.8 ng/ml and of 617.7 ng/ml for toxicity.

Conclusion

We first demonstrate the PK/PD relationship for cabozantinib. Severe toxicities are associated with a higher drug exposure, whereas inefficacy is associated with a lower drug exposure. Cabozantinib plasma drug monitoring may be useful to optimize clinical practice.

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Cabozantinib is a widely used TKI for mRCC for which there is no clearly noted pharmacokinetics/pharmacodynamics relationship.

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We demonstrated that a lower C_trough AUC and a higher drug apparent clearance (Cl/F) are associated with progressive disease.

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We demonstrated that a dose-limiting toxicity is associated with a higher C_trough and a lower clearance.

Exposure-toxicity relationship of cabozantinib in patients with renal cell cancer and salivary gland cancer

Cabozantinib is registered in fixed 60 mg dose. However, 46% to 62% of patients in the registration studies needed a dose reduction due to toxicity. Improved clinical efficacy has been observed in renal cell carcinoma patients (RCC) with a cabozantinib exposure greater than 750 μg/L. In our study we explored the cabozantinib exposure in patients with different tumour types. We included RCC patients from routine care and salivary gland carcinoma (SGC) patients from a phase II study with ≥1 measured C_min at steady‐state. The geometric mean (GM) C_min at the starting dose, at 40 mg and at best tolerated dose (BTD) were compared between both tumour types. Forty‐seven patients were included. All SGC patients (n = 22) started with 60 mg, while 52% of RCC patients started with 40 mg. GM C_min at the start dose was 1456 μg/L (95% CI: 1185‐1789) vs 682 μg/L (95% CI: 572‐812) (P < .001) for SGC and RCC patients, respectively. When dose‐normalised to 40 mg, SGC patients had a significantly higher cabozantinib exposure compared to RCC patients (C_min 971 μg/L [95% CI: 790‐1193] vs 669 μg/L [95% CI: 568‐788]) (P = .005). Dose reductions due to toxicity were needed in 91% and 60% of SGC and RCC patients, respectively. Median BTD was between 20 to 30 mg for SGC and 40 mg for RCC patients. GM C_min at BTD were comparable between the SGC and the RCC group, 694 μg/L (95% CI: 584‐824) vs 583 μg/L (95% CI: 496‐671) (P = .1). The observed cabozantinib exposure at BTD of approximately 600 μg/L is below the previously proposed target. Surprisingly, a comparable exposure at BTD was reached at different dosages of cabozantinib for SGC patients compared to RCC patients Further research is warranted to identify the optimal exposure and starting dose to balance efficacy and toxicity.

What's new?

Cabozantinib, a potent tyrosine kinase inhibitor that targets multiple signaling pathways, is approved for use against advanced renal cell carcinoma (RCC). Variations in cabozantinib clearance, however, warrant further investigation. Here, the authors evaluated cabozantinib exposure in RCC patients and in patients with salivary gland cancer (SGC). SGC patients were found to have significantly higher cabozantinib exposure compared to RCC patients following a 40 mg dose. However, the best‐tolerated cabozantinib exposure was equivalent (~600 μg/L) for both tumor types and was substantially below the previously proposed target. The findings offer insight on exposure, dose, and the balance between efficacy and toxicity for cabozantinib.

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.

Cabozantinib: An evolving therapy for hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is rising in incidence and remains a leading cause of cancer-related death. After a decade of disappointing trials following the approval of sorafenib for patients with advanced HCC, a number of tyrosine kinase inhibitors (TKIs) and monoclonal antibodies targeting angiogenesis and immune checkpoints have recently been approved. The phase 3 CELESTIAL trial demonstrated improved progression-free and overall survival with the TKI cabozantinib compared to placebo, supporting it as a treatment option for patients with advanced HCC previously treated with sorafenib. Cabozantinib blocks multiple key pathways of HCC pathogenesis, including VEGFR, MET, and the TAM (TYRO3, AXL, MER) family of receptor kinases, and promotes an immune-permissive tumor microenvironment. Here, we review the mechanisms of action of cabozantinib, including effects on tumor growth and its immunomodulatory properties, providing pre-clinical rationale for combination strategies with checkpoint inhibitors. We discuss the design and outcomes of CELESTIAL including improved survival across subgroups defined by age, disease etiology, baseline AFP level, prior therapies (including duration of prior sorafenib), and tumor burden. Cabozantinib had a manageable safety profile with dose modification. Studies combining cabozantinib with atezolizumab (COSMIC-312) and durvalumab (CAMILLA) in the first and second-line settings are ongoing, as well as a neoadjuvant study of cabozantinib with nivolumab. Future investigations are warranted to define the use of cabozantinib in patients with Child-Pugh B liver function and identify markers predictive of clinical benefit. The role of cabozantinib in HCC continues to evolve with an anticipated role in immunotherapy combinations.