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

Clinical considerations on monkeypox antiviral medications: An overview

Monkeypox (mpox), a virus belonging to the orthopoxvirus family, can cause a zoonotic infectious disease with morbidity and cosmetic complications. Therefore, effective antiviral drugs with appropriate safety profiles are important for the treatment of patients with mpox. To date, there is no FDA-approved drug for the treatment of mpox. However, tecovirimat, brincidofovir, and cidofovir are the candidate therapies for the management of mpox. Given the safety concerns following the use of these medications, we aimed to review evidence on the clinical considerations of mpox antiviral medications that will be useful to guide clinicians in the treatment approach. Based on the current evidence, tecovirimat has favorable clinical efficacy, safety, and side effect profile and it can be considered as first-line treatment for mpox.

Cabozantinib Safety With Different Anticoagulants in Patients With Renal Cell Carcinoma

BACKGROUND

In patients with renal cell carcinoma (RCC) on cabozantinib, venous thromboembolism (VTE) management remains challenging due to limited safety data regarding direct oral anticoagulants (DOACs) use in conjunction with cabozantinib. We investigated the safety of cabozantinib with different anticoagulants in patients with RCC.

METHODS

In this retrospective multicenter study (9 sites), patients with advanced RCC were allocated into 4 groups: (1) cabozantinib without anticoagulation, cabozantinib with concomitant use of (2) DOACs, (3) low molecular weight heparin (LMWH), or (4) warfarin. The primary safety endpoint was the proportion of major bleeding events (defined per International Society on Thrombosis and Hemostasis criteria). The primary efficacy endpoint was the proportion of new/recurrent VTE while anticoagulated.

RESULTS

Between 2016 and 2020, 298 patients with RCC received cabozantinib (no anticoagulant = 178, LMWH = 41, DOAC = 64, and warfarin = 15). Most patients had clear cell histology (78.5%) and IMDC intermediate/poor disease (78.2%). Cabozantinib was first, second, or ≥ third line in 21.8%, 31.9%, 43.3% of patients, respectively. Overall, there was no difference in major bleeding events between the no anticoagulant, LMWH, and DOAC groups (P = .088). Rate of new/recurrent VTE was similar among anticoagulant groups. Patients with a VTE had a statistically significantly worse survival than without a VTE (HR 1.48 [CI 95% 1.05-2.08, P = .02]).

CONCLUSION

This real-world cohort provides first data on bleeding and thrombosis complications in patients with RCC treated with cabozantinib with or without concurrent anticoagulation. DOACs appear safe for VTE treatment for patients with RCC on cabozantinib, but optimized anticoagulation management, including individualized risk-benefit discussion, remains important in clinical practice.

Addressing CPI resistance in NSCLC: targeting TAM receptors to modulate the tumor microenvironment and future prospects

Lung cancer remains a leading cause of cancer death worldwide, with non-small-cell lung cancer (NSCLC) accounting for the majority of cases. Immune checkpoint inhibitors (CPIs), including those targeting programmed cell death protein-1 and its ligand (PD-1/PD-L1), have revolutionized the treatment landscape for various cancers. Notably, PD-1/PD-L1 inhibitor-based regimens now form the standard first-line therapy for metastatic NSCLC, substantially improving patients' overall survival. Despite the progress made using CPI-based therapies in advanced NSCLC, most patients experience disease progression after an initial response due to resistance. Given the currently limited therapeutic options available for second-line and beyond settings in NSCLC, new treatment approaches are needed to improve long-term survival in these patients. Thus, CPI resistance is an emerging concept in cancer treatment and an active area of clinical research.Among the key mechanisms of CPI resistance is the immunosuppressive tumor microenvironment (TME). Effective CPI therapy is based on shifting immune responses against cancer cells, therefore, manipulating the immunosuppressive TME comprises an important strategy to combat CPI resistance. Several aspects of the TME can contribute to treatment resistance in NSCLC, including through the activation of Tyro3, Axl, MerTK (TAM) receptors which are essential pleiotropic regulators of immune homeostasis. Their roles include negatively modulating the immune response, therefore ectopic expression of TAM receptors in the context of cancer can contribute to the immunosuppressive, protumorigenic TME. Furthermore, TAM receptors represent important candidates to simultaneously target both tumor cells and immune cells in the TME. Clinical development of TAM receptor inhibitors (TAM RIs) is increasingly focused on their ability to rescue the antitumor immune response, thereby shifting the immunosuppressive TME to an immunostimulatory TME. There is a strong biological rationale for combining TAM RIs with a CPI to overcome resistance and improve long-term clinical responses in NSCLC. Combinatorial clinical trials of TAM RIs with CPIs are underway with encouraging preliminary results. This review outlines the key mechanisms of CPI resistance, including the role of the immunosuppressive TME, and discusses the rationale for targeting TAM receptors as a novel, promising therapeutic strategy to overcome CPI resistance in NSCLC.

Cancer Drug Approvals That Displaced Existing Standard-of-Care Therapies, 2016-2021

IMPORTANCE

Although several cancer drugs receive US Food and Drug Administration (FDA) approval each month, it is unclear how many of these cancer drugs transform the treatment landscape significantly by tumor group. Specifically, it remains unclear how many of these newly approved cancer drugs displace the existing standard-of-care therapies for their indication vs being added to existing therapies.

OBJECTIVE

To examine how many cancer drugs displace the standard-of-care therapies vs being added to existing therapy or filling breaks in systemic treatments in the metastatic setting, adjuvant setting, or maintenance setting.

DESIGN, SETTING, AND PARTICIPANTS

Retrospective cross-sectional study using landmark trials leading to FDA approval of cancer drugs between May 1, 2016, and May 31, 2021. The study evaluated all FDA approvals for cancer drugs between May 1, 2016, and May 31, 2021, using the FDA Oncology (Cancer)/Hematologic Malignancies Approval Notifications website. All clinical trials leading to FDA approval of cancer drugs during this period were examined.

MAIN OUTCOMES AND MEASURES

A drug was determined to have displaced the prior standard-of-care therapy by evaluating the comparator arm (or lack thereof) in the clinical trial leading to the drug's approval and also by reviewing National Comprehensive Cancer Network Guidelines. Cancer drug approvals were categorized as first-line displacing if a drug was approved for use in the first-line setting and displaced the prior standard-of-care drug for an indication, first-line drug alternatives/new if a drug was approved for use in the first-line setting but did not displace the standard of care at the time of approval or was a new drug that was first of its class for an approved indication, add on if a drug was approved in combination with a previously approved therapy for a disease or if a drug was approved for use in the adjuvant or maintenance settings, and later line if a drug was approved for use in the second-, third-, or later-line settings.

RESULTS

Between May 1, 2016, and May 31, 2021, there were 207 FDA cancer drug approvals in oncology and malignant hematology. Of these 207 approvals, 28 drugs (14%) were first-line displacing therapies. A total of 32 drugs (15%) were first-line drug alternatives/new drugs. A total of 61 drugs (29%) were add-on therapies. Finally, 86 drugs (42%) were approved as later-line therapies.

CONCLUSIONS AND RELEVANCE

In this study, most cancer drug approvals between 2016 and 2021 were in the later-line settings as opposed to displacing the current standard-of-care therapy for the approved indication. These later-line drugs may benefit patients with few alternatives but add to the cost of care because competition in the drug markets is a key factor in leading to lower drug prices.

Analysis of Toxicity and Clinical Outcomes in Full Versus Reduced Starting Dose Cabozantinib in Metastatic Renal Cell Carcinoma Patients

BACKGROUND

Full dose cabozantinib for metastatic renal cell carcinoma (mRCC) is 60 mg, but adverse events (AEs) may require dose reductions. Limited data exist comparing efficacy among cabozantinib doses. We compared AEs and clinical outcomes in mRCC patients treated with full vs. reduced starting cabozantinib dose.

METHODS

We performed a retrospective analysis of 87 mRCC patients treated with cabozantinib at Winship Cancer Institute from 2016 to 2019. Overall survival (OS), progression-free survival (PFS), and objective response (OR) rate measured clinical outcomes. AEs were collected from clinic notes and the most common were hypertension, mucositis/hand-foot skin reaction (HFSR), or gastrointestinal toxicity. Univariate analysis (UVA) between starting doses and AEs with clinical outcomes was performed using logistic regression model. Multivariable analysis was also performed using Cox proportional hazard model.

RESULTS

Most patients were men (71%) with clear-cell RCC (72%). The majority were IMDC intermediate (58%) or poor (35%) risk. One third received first-line cabozantinib and 64% had ≥3 baseline metastatic sites. Most patients (68%) required dose reduction from 60 mg or started at reduced dose without escalation. Reduced dose patients were more likely to have ≥3 distant metastatic sites (70% vs. 58%) and ≥2 prior lines of systemic therapy (50% vs. 40%) compared to full dose patients. UVA revealed a trend towards shorter OS (HR: 1.78, P = .095), PFS (HR: 1.50, P = .107), and lower chance of OR (HR:0.42, P = .149) among reduced dose patients. This trend did not hold in Multivariable analysis (OS HR: 1.20, P = .636; PFS HR: 1.23, P = .4662). Mucositis/HFSR and hypertension were significantly associated with improved outcomes in UVA.

CONCLUSIONS

Although we found a trend favoring full dose cabozantinib, this is likely due to worse baseline disease characteristics among patients starting on a reduced dose. Hypertension and mucositis/HFSR may be associated with improved outcomes. Larger studies are warranted to validate these findings.

Exploring the synergistic effects of cabozantinib and a programmed cell death protein 1 inhibitor in metastatic renal cell carcinoma with machine learning

Clinical evidence supports the combination of cabozantinib with an immune checkpoint inhibitor for the treatment of metastatic clear cell renal cell carcinoma (mccRCC) and suggests a synergistic antitumour activity of this combination. Nevertheless, the biological basis of this synergy is not fully characterized. We studied the mechanisms underpinning the potential synergism of cabozantinib combined with a PD1 inhibitor in mccRCC and delved into cabozantinib monotherapy properties supporting its role to partner these combinations. To model physiological drug action, we used a machine learning-based technology known as Therapeutic Performance Mapping Systems, applying two approaches: Artificial Neural Networks and Sampling Methods. We found that the combined therapy was predicted to exert a wide therapeutic action in the tumour and the microenvironment. Cabozantinib may enhance the effects of PD1 inhibitors on immunosurveillance by modulating the innate and adaptive immune system, through the inhibition of VEGF-VEGFR and Gas6-AXL/TYRO3/MER (TAM) axes, while the PD1 inhibitors may boost the antiangiogenic and pro–apoptotic effects of cabozantinib by modulating angiogenesis and T-cell cytotoxicity. Cabozantinib alone was predicted to restore cellular adhesion and hamper tumour proliferation and invasion. These data provide a biological rationale and further support for cabozantinib plus PD1 inhibitor combination and may guide future nonclinical and clinical research.

Temporal trends of adverse events and costs of nivolumab plus ipilimumab versus sunitinib in advanced renal cell carcinoma

Aims: To assess grade 3/4 adverse events (AEs) and costs of first-line nivolumab plus ipilimumab (NIVO + IPI) versus sunitinib in advanced or metastatic renal cell carcinoma. Methods: Individual patient data from the all treated population in the CheckMate 214 trial (NIVO + IPI, n = 547; sunitinib, n = 535) were used to calculate the number of AEs. AE unit costs were obtained from US 2017 Healthcare Cost and Utilization Project and inflated to 2020 values. Results: The proportion of patients experiencing grade 3/4 AEs decreased over time. Patients who received NIVO + IPI had lower average per-patient all-cause grade 3/4 AE costs versus sunitinib (12-month: US$15,170 vs US$20,342; 42-month: US$19,096 vs US$27,473). Conclusion: Treatment with NIVO + IPI was associated with lower grade 3/4 AE costs than sunitinib.

All bone metastases are not created equal: Revisiting treatment resistance in renal cell carcinoma

Renal cell carcinoma (RCC) is the most common malignancy of the kidney, representing 80-90% of renal neoplasms, and is associated with a five-year overall survival rate of approximately 74%. The second most common site of metastasis is bone. As patients are living longer due to new RCC targeting agents and immunotherapy, RCC bone metastases (RCCBM) treatment failure is more prevalent. Bone metastasis formation in RCC is indicative of a more aggressive disease and worse prognosis. Osteolysis is a prominent feature and causes SRE, including pathologic fractures. Bone metastasis from other tumors such as lung, breast, and prostate cancer, are more effectively treated with bisphosphonates and denosumab, thereby decreasing the need for palliative surgical intervention. Resistance to these antiresportives in RCCBM reflects unique cellular and molecular mechanisms in the bone microenvironment that promote progression via inhibition of the anabolic reparative response. Identification of critical mechanisms underlying RCCBM induced anabolic impairment could provide needed insight into how to improve treatment outcomes for patients with RCCBM, with the goals of minimizing progression that necessitates palliative surgery and improving survival.

Functional evaluation of vandetanib metabolism by CYP3A4 variants and potential drug interactions in vitro

AIM

To investigate the enzymatic properties of cytochrome P450 3A4 (CYP3A4) variants and their ability to metabolize vandetanib (VNT) in vitro, and to study potential drug interactions in combination with VNT.

METHOD

Recombinant CYP3A4 cell microsomes were prepared using a Bac-to-Bac baculovirus expression system. Enzymatic reactions were carried out, and the metabolites were determined by ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS).

RESULTS

The activities of 27 CYP3A4 variants were determined to assess the degree of VNT metabolism that occurred. Analysis indicated that there was enhanced intrinsic clearance (V_max/K_m, CLint) for eight variants (CYP3A4.2, 3, 9, 15, 16, 29, 32, and 33), while there was a significant decrease in CYP3A4.5, 7, 8, 10-14, 17-20, 23, 24, 28, 31, and 34. Compared with CYP3A4.1, no significant differences were found for CYP3A4.6 and 30. Furthermore, the relative clearances were compared between VNT and cabozantinib, which were all metabolized by CYP3A4 with the same indications. When combined with ketoconazole, which is a CYP inhibitor, obvious differences were observed in the potency of VNT between different variants, including CYP3A4.2, 15, and 18.

CONCLUSION

This comprehensive assessment of CYP3A4 variants provides significant insights into the allele-specific metabolism of VNT and drug interactions in vitro. We hope that these comprehensive data will provide references and predictions for the clinical application of VNT.

Multi-target weapons: diaryl-pyrazoline thiazolidinediones simultaneously targeting VEGFR-2 and HDAC cancer hallmarks

In anticancer drug discovery, multi-targeting compounds have been beneficial due to their advantages over single-targeting compounds. For instance, VEGFR-2 has a crucial role in angiogenesis and cancer management, whereas HDACs are well-known regulators of epigenetics and have been known to contribute significantly to angiogenesis and carcinogenesis. Herein, we have reported nineteen novel VEGFR-2 and HDAC dual-targeting analogs containing diaryl-pyrazoline thiazolidinediones and their in vitro and in vivo biological evaluation. In particular, the most promising compound 14c has emerged as a dual inhibitor of VEGFR-2 and HDAC. It demonstrated anti-angiogenic activity by inhibiting in vitro HUVEC proliferation, migration, and tube formation. Moreover, an in vivo CAM assay showed that 14c repressed new capillary formation in CAMs. In particular, 14c exhibited cytotoxicity potential on different cancer cell lines such as MCF-7, K562, A549, and HT-29. Additionally, 14c demonstrated significant potency and selectivity against HDAC4 in the sub-micromolar range. To materialize the hypothesis, we also performed molecular docking on the crystal structures of both VEGFR-2 (PDB ID: 1YWN) and HDAC4 (PDB-ID: 4CBY), which corroborated the designing and biological activity. The results indicated that compound 14c could be a potential lead to develop more optimized multi-target analogs with enhanced potency and selectivity.

Double-edged Swords: Diaryl pyrazoline thiazolidinediones synchronously targeting cancer epigenetics and angiogenesis

In the present study, two novel series of compounds incorporating naphthyl and pyridyl linker were synthesized and biological assays revealed 5-((6-(2-(5-(2-chlorophenyl)-3-(4-fluorophenyl)-4,5-dihydro-1H-pyrazol-1-yl)-2-oxoethoxy) naphthalene-2-yl)methylene)thiazolidine-2,4-dione (14b) as the most potent dual inhibitors of vascular endothelial growth factors receptor-2 (VEGFR-2) and histone deacetylase 4 (HDAC4). Compounds 13b, 14b, 17f, and 21f were found to stabilize HDAC4; where, pyridyl linker swords were endowed with higher stabilization effects than naphthyl linker. Also, 13b and 14b showed best inhibitory activity on VEGFR-2 as compared to others. Compound 14b was most potent as evident by in-vitro and in-vivo biological assessments. It displayed anti-angiogenic potential by inhibiting endothelial cell proliferation, migration, tube formation and also suppressed new capillary formation in the growing chick chorioallantoic membranes (CAMs). It showed selectivity and potency towards HDAC4 as compared to other HDAC isoforms. Compound 14b (25 mg/kg, i.p.) also indicated exceptional antitumor efficacy on in-vivo animal xenograft model of human colorectal adenocarcinoma (HT-29). The mechanism of action of 14b was also confirmed by western blot.

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.

TAM kinase inhibition and immune checkpoint blockade- a winning combination in cancer treatment?

Introduction: Immune checkpoint inhibitors (ICI) have shown great promise in a wide spectrum of malignancies. However, responses are not always durable, and this mode of treatment is only effective in a subset of patients. As such, there exists an unmet need for novel approaches to bolster ICI efficacy.Areas covered: We review the role of the Tyro3, Axl, and Mer (TAM) receptor tyrosine kinases in promoting tumor-induced immune suppression and discuss the benefits that may be derived from combining ICI with TAM kinase-targeted tyrosine kinase inhibitors. We searched the MEDLINE Public Library of Medicine (PubMed) and EMBASE databases and referred to ClinicalTrials.gov for relevant ongoing studies.Expert opinion: Targeting of TAM kinases may improve the efficacy of immune checkpoint blockade. However, it remains to be determined whether this effect will be better achieved by the selective targeting of each TAM receptor, depending on the context, or by multi-receptor TAM inhibitors. Triple inhibition of all TAM receptors is more likely to be associated with an increased risk for adverse events. Clinical trial designs should use high-resolution clinical endpoints and proper control arms to determine the synergistic effects of combining TAM inhibition with immune checkpoint blockade.

The Potential Gut Microbiota-Mediated Treatment Options for Liver Cancer

Primary liver cancer is one of the leading causes of cancer death worldwide. Surgical and non-surgical treatments are optional for liver cancer therapy based on the cancer stage. Accumulating studies show that the gut–liver axis influences the progression of liver diseases, including liver inflammation, fibrosis, cirrhosis, and cancer. However, the role of gut microbiota and their derived components and metabolites in liver cancer remains to be further clarified. In this review, we discuss the roles of gut microbiota and specific bacterial species in HCC and the strategies to modulate gut microbiota to improve antitumor therapy. Given the limitation of current treatments, gut microbiota-mediated therapy is a potential option for HCC treatment, including fiber diet and vegetable diet, antimicrobials, probiotics, and pharmaceutical inhibitors. Also, gut microbiota can be used as a marker for early diagnosis of HCC. HCC occurs dependent on various environmental and genetic factors, including diet and sex. Furthermore, gut microbiota impacts the immunotherapy of HCC treatment. Therefore, a better understanding of the role of the gut–liver axis in liver cancer is critically important to improve therapeutic efficacy.

First-line treatments for advanced renal-cell carcinoma with immune checkpoint inhibitors: systematic review, network meta-analysis and cost-effectiveness analysis

Background:

Immune checkpoint inhibitors (ICIs) are effective for advanced renal-cell carcinoma (aRCC) but can increase costs. This study compares the efficacy, safety and cost-effectiveness of ICIs for newly diagnosed aRCC patients in the first-line setting.

Methods:

Trials evaluating ICI regimens as first-line treatment for newly diagnosed aRCC were searched and included. A network meta-analysis (NMA) was conducted, and a cost-effectiveness analysis was performed from the US payer’s perspective. The key outcomes were overall survival (OS) and progression-free survival (PFS) in the NMA, and quality-adjusted life years (QALYs), costs and the incremental cost-effectiveness ratio (ICER) in the cost-effectiveness analysis.

Results:

Four randomized controlled trials (RCTs) involving 3758 patients receiving first-line ICIs treatment were analyzed. The NMA showed that pembrolizumab plus axitinib was ranked higher than the other three ICI regimens and sunitinib in the overall population. Nivolumab plus ipilimumab and pembrolizumab plus axitinib achieved more health benefits than the other ICI regimens and sunitinib in programmed death ligand 1 (PD-L1)-positive and negative tumors, respectively. Among the four ICI regimens, only the ICERs of nivolumab plus ipilimumab over sunitinib were lower than the willingness-to-pay threshold ($150,000/QALY) in the overall and PD-L1-positive populations, and none of four ICI regimens were lower than $150,000/QALY in PD-L1-negative populations.

Conclusions:

The NMA and cost-effectiveness analysis revealed that nivolumab plus ipilimumab is the most favorable first-line treatment for PD-L1-positive aRCC compared with other ICI regimens and sunitinib. Pembrolizumab plus axitinib is likely to be an alternative for PD-L1-negative aRCC due to its more favorable health advantages.

Optimizing treatment of renal cell carcinoma with VEGFR-TKIs: a comparison of clinical pharmacology and drug-drug interactions of anti-angiogenic drugs

Anti-angiogenic treatment is an important option that has changed the therapeutic landscape in various tumors, particularly in patients affected by renal cell carcinoma (RCC). Agents that block signaling pathways governing tumor angiogenesis have raised high expectations among clinicians. Vascular endothelial growth factor receptor-tyrosine kinase inhibitors (VEGFR-TKIs) comprise a heterogeneous class of drugs with distinct pharmacological profiles, including potency, selectivity, pharmacokinetics and drug-drug interactions. Among them, tivozanib is one of the last TKIs introduced in the clinical practice; this drug selectively targets VEGFRs, it is characterized by a favorable pharmacokinetics and safety profile and has been approved as first-line treatment for patients with metastatic RCC (mRCC). In this article, we describe the clinical pharmacology of selected VEGFR-TKIs used for the treatment of mRCC, highlighting the relevant differences; moreover we aim to define the main pharmacologic characteristics of these drug.

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.