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

Immune checkpoint inhibitors-related endocrinopathies exhibit increased severity in breast cancer patients: a real-world study

PURPOSE

This study aims to systematically evaluate the incidence of immune checkpoint inhibitors (ICIs)-related endocrinopathies and their onset time in patients with breast cancer (BC) in a real-world setting.

METHODS

An analysis was conducted on the medical records of 122 BC patients who underwent ICIs therapy at the Department of Breast Surgery, Guangdong Provincial People's Hospital, from April 2019 to September 2021. Follow-up data continued until October 2022.

RESULTS

The research indicated that 60.66% of BC patients experienced ICI-related endocrinopathies. The endocrinopathies included pituitary injury (7.38%), primary thyroid dysfunction (34.43%), supranormal fasting blood glucose or glycohemoglobin levels (16.39%), and adrenal injury (2.46%). Subgroup analyses were further performed based on clinical characteristics, demonstrated variability in the incidence of ICI-related endocrinopathies. Notably, subpopulations harboring genetic mutations exhibited a markedly higher prevalence of hypophysitis, as evidenced by a statistically significant association (P = 0.022). Similarly, individuals with HER2 positivity were found to have a significantly increased incidence of pancreatic islet injury (P = 0.023). Moreover, the study documented that the median onset times of ICIs-related endocrinopathies in pituitary, thyroid, pancreatic, and adrenal damage were 264, 184, 99 and 141 days, respectively, which were substantially longer compared to previous reports involving other tumors. Remarkably, even after 500 days of initiating ICI therapy, new cases of ICI-related endocrine disorders continue to emerge, suggesting a situation of delayed onset of ICI-related endocrinopathies in BC patients.

CONCLUSION

The retrospective analysis confirmed a higher incidence and longer median onset time of ICI-related endocrinopathies in BC patients compared to other cancers. These outcomes underscore the critical need for regular and extended monitoring of endocrine functions in BC patients receiving ICI therapy, advocating for personalized monitoring approaches based on individual clinical profiles.

A fatal case of cabozantinib-induced cardiomyopathy

Cabozantinib, a multi-kinase receptor inhibitor, is utilized in the treatment of advanced malignancies such as metastatic renal cancers. While rare, cabozantinib-induced cardiotoxicity has emerged as a recognized adverse effect with potentially reversible outcomes. We report the case of a 55-year-old male who developed fatal cardiomyopathy 4 months after initiating cabozantinib therapy. Despite its rarity, cardiomyopathy after initiation of cabozantinib can be lethal if not diagnosed early. This case underscores a significant gap in the surveillance of patients treated with newer agents like cabozantinib. Larger observational studies are needed to assess the prevalence and impact of cardiomyopathy after initiation of cabozantinib therapy, and to determine the cost-effectiveness of early surveillance protocols.

Capmatinib is an effective treatment for MET-fusion driven pediatric high-grade glioma and synergizes with radiotherapy

BACKGROUND

Pediatric-type diffuse high-grade glioma (pHGG) is the most frequent malignant brain tumor in children and can be subclassified into multiple entities. Fusion genes activating the MET receptor tyrosine kinase often occur in infant-type hemispheric glioma (IHG) but also in other pHGG and are associated with devastating morbidity and mortality.

METHODS

To identify new treatment options, we established and characterized two novel orthotopic mouse models harboring distinct MET fusions. These included an immunocompetent, murine allograft model and patient-derived orthotopic xenografts (PDOX) from a MET-fusion IHG patient who failed conventional therapy and targeted therapy with cabozantinib. With these models, we analyzed the efficacy and pharmacokinetic properties of three MET inhibitors, capmatinib, crizotinib and cabozantinib, alone or combined with radiotherapy.

RESULTS

Capmatinib showed superior brain pharmacokinetic properties and greater in vitro and in vivo efficacy than cabozantinib or crizotinib in both models. The PDOX models recapitulated the poor efficacy of cabozantinib experienced by the patient. In contrast, capmatinib extended survival and induced long-term progression-free survival when combined with radiotherapy in two complementary mouse models. Capmatinib treatment increased radiation-induced DNA double-strand breaks and delayed their repair.

CONCLUSIONS

We comprehensively investigated the combination of MET inhibition and radiotherapy as a novel treatment option for MET-driven pHGG. Our seminal preclinical data package includes pharmacokinetic characterization, recapitulation of clinical outcomes, coinciding results from multiple complementing in vivo studies, and insights into molecular mechanism underlying increased efficacy. Taken together, we demonstrate the groundbreaking efficacy of capmatinib and radiation as a highly promising concept for future clinical trials.

Comparative efficacy and safety of cabozantinib for malignant tumors: a systematic review and meta-analysis

OBJECTIVES

To provide a more comprehensive understanding of the efficacy and safety profile of cabozantinib versus placebo in malignant tumors, we conducted a systematic review and meta-analysis. This involved analyzing a collection of published randomized controlled trials to assess the outcomes.

METHODS

We used RevMan5.3 software to evaluate the outcomes of the collected studies. The primary outcome we focused on was progression-free survival (PFS), and the secondary outcomes included overall survival (OS) and disease control rate (DCR).

RESULTS

Our findings revealed that compared to placebo, cabozantinib significantly extended the PFS of patients [hazard ratios (HR) 0.37, 95% confidence intervals (CI): 0.32, 0.43, p < 0.00001]. Additionally, cabozantinib improved the OS of patients [HR 0.78, 95%CI: 0.68, 0.91, p = 0.002]. While it is important to note that cabozantinib was associated with a higher likelihood of causing digestive, cutaneous, and cardiovascular related adverse events [relative risk (RR) 4.40, 95% CI: 3.10, 6.25, p < 0.00001].

CONCLUSION

Based on our analysis, cabozantinib significantly prolonged the PFS and OS of patients with malignant tumors (p < 0.01). We recommend the use of cabozantinib in treating advanced malignant tumors. However, it is important to continuously monitor and manage the drug-related adverse events.

REGISTRATION

PROSPERO (No. CRD42023449261).

Recent advances of anti-angiogenic inhibitors targeting VEGF/VEGFR axis

Vascular endothelial growth factors (VEGF), Vascular endothelial growth factor receptors (VEGFR) and their downstream signaling pathways are promising targets in anti-angiogenic therapy. They constitute a crucial system to regulate physiological and pathological angiogenesis. In the last 20 years, many anti-angiogenic drugs have been developed based on VEGF/VEGFR system to treat diverse cancers and retinopathies, and new drugs with improved properties continue to emerge at a fast rate. They consist of different molecular structures and characteristics, which enable them to inhibit the interaction of VEGF/VEGFR, to inhibit the activity of VEGFR tyrosine kinase (TK), or to inhibit VEGFR downstream signaling. In this paper, we reviewed the development of marketed anti-angiogenic drugs involved in the VEGF/VEGFR axis, as well as some important drug candidates in clinical trials. We discuss their mode of action, their clinical benefits, and the current challenges that will need to be addressed by the next-generation of anti-angiogenic drugs. We focus on the molecular structures and characteristics of each drug, including those approved only in China.

How is overall survival assessed in randomised clinical trials in cancer and are subsequent treatment lines considered? A systematic review

BACKGROUND

Overall survival is the "gold standard" endpoint in cancer clinical trials. It plays a key role in determining the clinical- and cost-effectiveness of a new intervention and whether it is recommended for use in standard of care. The assessment of overall survival usually requires trial participants to be followed up for a long period of time. In this time, they may stop receiving the trial intervention and receive subsequent anti-cancer treatments, which also aim to extend survival, during trial follow-up. This can potentially change the interpretation of overall survival in the context of the clinical trial. This review aimed to determine how overall survival has been assessed in cancer clinical trials and whether subsequent anti-cancer treatments are considered.

METHODS

Two searches were conducted using MEDLINE within OVID© on the 9th of November 2021. The first sought to identify papers publishing overall survival results from randomised controlled trials in eight reputable journals and the second to identify papers mentioning or considering subsequent treatments. Papers published since 2010 were included if presenting or discussing overall survival in the context of treating cancer.

RESULTS

One hundred and thirty-four papers were included. The majority of these were presenting clinical trial results (98, 73%). Of these, 45 (46%) reported overall survival as a (co-) primary endpoint. A lower proportion of papers including overall survival as a (co-) primary endpoint compared to a secondary endpoint were published in recent years. The primary analysis of overall survival varied across the papers. Fifty-nine (60%) mentioned subsequent treatments. Seven papers performed additional analysis, primarily when patients in the control arm received the experimental treatment during trial follow-up (treatment switching).

DISCUSSION

Overall survival has steadily moved from being the primary to a secondary endpoint. However, it is still of interest with papers presenting overall survival results with the caveat of subsequent treatments, but little or no investigation into their effect. This review shows that there is a methodological gap for what researchers should do when trial participants receive anti-cancer treatment during trial follow-up. Future research will identify the stakeholder opinions, on how this methodological gap should be addressed.

Cabozantinib for the treatment of solid tumors: a systematic review

Background:

Cabozantinib is approved, in various settings, for the treatment of renal cell carcinoma, medullary thyroid cancer, and hepatocellular carcinoma, and it has been investigated for the treatment of other cancers. With the available evidence and the real-world performance of cabozantinib compared with clinical trial data, we performed a systematic review of cabozantinib monotherapy as treatment for solid tumors in adults.

Methods:

This study was designed in accordance with Preferred Reporting Items for Systematic Reviews and Meta-Analyses and registered with PROSPERO (CRD42020144680). We searched for clinical and observational studies of cabozantinib monotherapy for solid tumors using Embase, MEDLINE, and Cochrane databases (October 2020), and screened relevant congress abstracts. Eligible studies reported clinical or safety outcomes, or biomarker data. Small studies (n < 25) and studies of cabozantinib combination therapies were excluded. Quality was assessed using National Institute for Health and Care Excellence methodology, and study characteristics were described qualitatively.

Results:

Of 2888 citations, 114 were included (52 randomized studies, 29 observational studies, 32 nonrandomized phase I or II studies or pilot trials, and 1 analysis of data from a randomized study and a nonrandomized study). Beyond approved indications, other tumors studied were castration-resistant prostate cancer, urothelial carcinoma, Ewing sarcoma, osteosarcoma, uveal melanoma, non-small-cell lung cancer, Merkel cell carcinoma, glioblastoma, pheochromocytomas and paragangliomas, cholangiocarcinoma, gastrointestinal stromal tumor, colorectal cancer, salivary gland cancer, carcinoid and pancreatic neuroendocrine tumors, and breast, endometrial and ovarian cancers. The most common adverse events were hypertension, diarrhea, and fatigue.

Conclusion:

The identified evidence demonstrates the positive efficacy/effectiveness of cabozantinib monotherapy in various solid tumor types, with safety findings being consistent with those observed with other VEGFR-targeting tyrosine kinase inhibitors. When available, real-world findings were consistent with the data reported from clinical trials. A limitation of this review is the high proportion of abstracts; however, this allowed us to capture the most up-to-date findings.

CaboPoint: a phase II study of cabozantinib as second-line treatment in patients with metastatic renal cell carcinoma

Cabozantinib is an inhibitor of multiple tyrosine kinases, including AXL, MET and VEGF receptors. Here, we describe the rationale and design for the phase II CaboPoint trial (ClinicalTrials.gov identifier: NCT03945773), which will evaluate the efficacy and safety of cabozantinib as a second-line treatment in patients with unresectable, locally advanced or metastatic renal cell carcinoma whose disease has progressed despite checkpoint inhibitor therapy. Patients will be recruited into two cohorts: prior ipilimumab plus nivolumab (cohort A) or prior checkpoint inhibitor-VEGF-targeted therapy (cohort B). All patients will receive once-daily oral cabozantinib 60 mg for up to 18 months. The primary end point is objective response rate. Secondary end points include overall survival, progression-free survival and safety.

Evolving cancer-niche interactions and therapeutic targets during bone metastasis

Many cancer types metastasize to bone. This propensity may be a product of genetic traits of the primary tumour in some cancers. Upon arrival, cancer cells establish interactions with various bone-resident cells during the process of colonization. These interactions, to a large degree, dictate cancer cell fates at multiple steps of the metastatic cascade, from single cells to overt metastases. The bone microenvironment may even influence cancer cells to subsequently spread to multiple other organs. Therefore, it is imperative to spatiotemporally delineate the evolving cancer-bone crosstalk during bone colonization. In this Review, we provide a summary of the bone microenvironment and its impact on bone metastasis. On the basis of the microscopic anatomy, we tentatively define a roadmap of the journey of cancer cells through bone relative to various microenvironment components, including the potential of bone to function as a launch pad for secondary metastasis. Finally, we examine common and distinct features of bone metastasis from various cancer types. Our goal is to stimulate future studies leading to the development of a broader scope of potent therapies.

Cabozantinib combination therapy for the treatment of solid tumors: a systematic review

Background:

Cabozantinib monotherapy is approved for the treatment of several types of solid tumors. Investigation into the use of cabozantinib combined with other therapies is increasing. To understand the evidence in this area, we performed a systematic review of cabozantinib combination therapy for the treatment of solid tumors in adults.

Methods:

This study was designed in accordance with Preferred Reporting Items for Systematic Reviews and Meta-Analyses, and the protocol was registered with PROSPERO (CRD42020144680). On 9 October 2020, we searched for clinical trials and observational studies of cabozantinib as part of a combination therapy for solid tumors using Embase, MEDLINE, and Cochrane databases, and by screening relevant congress abstracts. Eligible studies reported clinical or safety outcomes, or biomarker data. Randomized and observational studies with a sample size of fewer than 25 and studies of cabozantinib monotherapy were excluded. For each study, quality was assessed using National Institute for Health and Care Excellence methodology, and the study characteristics were described qualitatively. This study was funded by Ipsen.

Results:

Of 2421 citations identified, 32 articles were included (6 with results from randomized studies, 24 with results from non-randomized phase I or II studies, and 2 with results from both). The most commonly studied tumor types were metastatic urothelial carcinoma/genitourinary tumors and castration-resistant prostate cancer (CRPC). Findings from randomized studies suggested that cabozantinib combined with other therapies may lead to better progression-free survival than some current standards of care in renal cell carcinoma, CRPC, and non-small-cell lung cancer. The most common adverse events were hypertension, diarrhea, and fatigue.

Conclusion:

This review demonstrates the promising efficacy outcomes of cabozantinib combined with other therapies, and a safety profile similar to cabozantinib alone. However, the findings are limited by the fact that most of the identified studies were reported as congress abstracts only. More evidence from randomized trials is needed to explore cabozantinib as a combination therapy further.

Identification of a Five-Gene Prognostic Signature Related to B Cells Infiltration in Pancreatic Adenocarcinoma

Background

Pancreatic adenocarcinoma (PAAD) is an extremely malignant cancer. Immunotherapy is a promising avenue to increase the survival time of patients with PAAD.

Methods

RNA sequencing and clinical data for PAAD were downloaded from the TCGA database. The ssGSEA method and weighted gene co-expression network analysis were used to calculate the relative abundance of tumor-infiltrating immune cells and identify the related modules. Least absolute shrinkage and selection operator (LASSO) and Cox regression analyses were used to construct a prognostic model. MCPcounter and EPIC were also used to assess immune cell components using gene expression profiles.

Results

The B cells closely related module was identified, and five genes, including ARID5A, CLEC2B, MICAL1, MZB1, and RAPGEF1, were ultimately selected to establish a prognostic signature to calculate the risk scores of PAAD patients. Kaplan–Meier curves showed worse survival in the high-risk patients (p < 0.05), and the area under the receiver operating characteristic (ROC) curves of risk score for 1-year and 3-year survival were 0.78 and 0.80, respectively, based on the training set. Similar results were verified using the validated and combined sets. Interestingly, the low-risk group presented significantly elevated immune and stromal scores, proportion of B cells, and associations between these five genes and B cells were identified using multiple methods including ssGSEA, MCPcounter, and EPIC.

Conclusion

This is the first attempt to study a B cells-related prognostic signature, which is instrumental in the exploration of novel prognostic biomarkers in PAAD.

Antitumor effects of the multi-target tyrosine kinase inhibitor cabozantinib: a comprehensive review of the preclinical evidence

INTRODUCTION

Altered receptor tyrosine kinase (RTK) signaling contributes to tumorigenesis and suppression of immune-mediated destruction of cancer cells. Cabozantinib is an oral tyrosine kinase inhibitor that inhibits several RTKs involved in tumorigenesis, and is approved for the treatment of patients with progressive metastatic medullary thyroid cancer, advanced renal cell carcinoma, and hepatocellular carcinoma that has been previously treated with sorafenib.

AREAS COVERED

We present an up-to-date evaluation of preclinical evidence for RTK inhibition with cabozantinib, specifically VEGFR, MET, KIT, RET, AXL, FLT3, and associated antitumor effects. Preclinical investigations of cabozantinib in combination with other anticancer drugs are also reviewed.

EXPERT OPINION

Preclinical evidence shows that cabozantinib has antitumor activity against various cancer cells and exhibits synergy with other anticancer agents, including immune checkpoint inhibitors and hormone receptor or metabolic pathway inhibitors. Further optimization of cabozantinib treatment requires the identification of biomarkers of response and resistance, and exploration of complementary drug targets. Investigation of mechanisms of adaptive resistance, such as epithelial to mesenchymal transition (cancer intrinsic) and immunomodulation by the tumor microenvironment (cancer extrinsic), as well as identification of novel drug targets based on characterization of cancer stem cell metabolomic phenotypes, appear to be promising approaches.

Can we rely on synthetic pharmacotherapy for the treatment of glioblastoma?

Introduction: Despite decades of clinical trials utilizing conventional and novel therapeutics, the effective treatment of glioblastoma remains one of the most formidable challenges in oncology. Current standard of care includes surgery and chemoradiation. Synthetic pharmacotherapies continue to be explored as potential therapeutic options for glioblastoma patients.Areas covered: This study reviews synthetic pharmacotherapies that are currently under investigation in phase I-III clinical trials. The authors of this study highlight the mechanisms of action of the synthetic pharmacotherapy agents under investigation, outline the available evidence for their utility based on the literature, and summarize the current landscape.Expert opinion: Although warranting further investigation, the studies generally highlighted here have not shown remarkable changes in clinical benefits beyond what has already been established with radiochemotherapy. As we develop more synthetics, we will likely need to combine them with other synthetics to target multiple separate molecular pathways. There is considerable potential when this treatment strategy is guided by molecular profiling approaches which seek to stratify patients based on treatments that would be most efficacious for them.

SU5416 plus hypoxia but not selective VEGFR2 inhibition with cabozantinib plus hypoxia induces pulmonary hypertension in rats: potential role of BMPR2 signaling

SU5416 plus chronic hypoxia causes pulmonary arterial hypertension in rats and is assumed to occur through VEGFR2 inhibition. Cabozantinib is a far more potent VEGFR2 inhibitor than SU5416. Therefore, we hypothesized that cabozantinib plus hypoxia would induce severe pulmonary arterial hypertension in rats. Cell proliferation and pharmacokinetic studies were performed. Rats were given SU5416 or cabozantinib subcutaneously or via osmotic pump and kept hypoxic for three weeks. Right ventricular systolic pressure and hypertrophy were evaluated at days 14 and 28 following removal from hypoxia. Right ventricular fibrosis was evaluated with Picro-Sirius Red staining. Kinome inhibition profiles of SU5416 and cabozantinib were performed. Inhibitor binding constants of SU5416 and cabozantinib for BMPR2 were determined and Nanostring analyses of lung mRNA were performed. Cabozantinib was a more potent VEGFR inhibitor than SU5416 and had a longer half-life in rats. Cabozantinib subcutaneous plus hypoxia did not induce severe pulmonary arterial hypertension. Right ventricular systolic pressure at 14 and 28 days post-hypoxia was 36.8 ± 2.3 mmHg and 36.2 ± 3.4 mmHg, respectively, versus 27.5 ± 1.5 mmHg in normal controls. For cabozantinib given by osmotic pump during hypoxia, right ventricular systolic pressure was 40.0 ± 3.1 mmHg at 14 days and 27.9 ± 1.9 mmHg at 28 days post-hypoxia. SU5416 plus hypoxia induced severe pulmonary arterial hypertension (right ventricular systolic pressure 61.9 ± 6.1 mmHg and 64.9 ± 8.4 mmHg at 14 and 28 days post-hypoxia, respectively). Cabozantinib induced less right ventricular hypertrophy (right ventricular free wall weight/(left ventricular free wall weight + interventricular septum weight) at 14 days post-hypoxia compared to SU5416. Right ventricular fibrosis was more extensive in the SU5416 groups compared to the cabozantinib groups. SU5416 (but not cabozantinib) inhibited BMPR2. Nanostring analyses showed effects on pulmonary gene expression of BMP10 and VEGFR1 in the SU5416 28 days post-hypoxia group. In conclusion, selective VEGFR2 inhibition using cabozantinib plus hypoxia did not induce severe pulmonary arterial hypertension. Severe pulmonary arterial hypertension due to SU5416 plus hypoxia may be due to combined VEGFR2 and BMPR2 inhibition.

Molecular Mechanisms of Hepatoblastoma

Hepatoblastoma (HB) is the predominant primary liver tumor in children. While the prognosis is favorable when the tumor can be resected, the outcome is dismal for patients with progressed HB. Therefore, a better understanding of the molecular mechanisms responsible for HB is imperative for early detection and effective treatment. Sequencing analysis of human HB specimens unraveled the pivotal role of Wnt/β-catenin pathway activation in this disease. Nonetheless, β-catenin activation alone does not suffice to induce HB, implying the need for additional alterations. Perturbations of several pathways, including Hippo, Hedgehog, NRF2/KEAP1, HGF/c-Met, NK-1R/SP, and PI3K/AKT/mTOR cascades and aberrant activation of c-MYC, n-MYC, and EZH2 proto-oncogenes, have been identified in HB, although their role requires additional investigation. Here, we summarize the current knowledge on HB molecular pathogenesis, the relevance of the preclinical findings for the human disease, and the innovative therapeutic strategies that could be beneficial for the treatment of HB patients.

Circulating tumor DNA analysis of metastatic renal cell carcinoma

The genomic landscape of metastatic renal cell carcinoma (RCC) is not well understood, and currently available data suggest that it is functionally distinct from that of localized tumors. Additionally, the large number of approved and trial agents used to treat metastatic RCC likely cause selective adaptations in the tumors. Circulating tumor DNA (ctDNA) is a platform to non-invasively determine the genomic profiles of these tumors. The objectives of the present study were to corroborate previous ctDNA studies in metastatic RCC, to identify novel mutations in metastatic RCC, and to compare ctDNA profiles obtained from plasma and urine in patients with metastatic RCC. ctDNA sequencing using the plasma and urine of 50 patients with metastatic RCC who received ctDNA profiling as part of routine clinical care at a single institution was performed using an investigational 120-gene panel. Genomic alterations (GAs) were identified in all 50 patients. The genes with the most GAs were GNAS, PTEN, MYC, MET and HNF1A and novel mutations in additional genes were identified. A significant correlation between the number of GAs detected in matched urine and plasma samples was also identified, but only 28.1% of GAs detected in plasma samples were also detected in matched urine samples. The results of the present study were consistent with those of the largest previous study of ctDNA from patients with metastatic RCC and may help identify additional potential targets for the treatment of such patients.

Clinical use of vascular endothelial growth factor receptor inhibitors for the treatment of renal cell carcinoma

In recent years, there have been increased incidences of metastatic renal cell carcinoma (RCC), which is refractory to conventional chemotherapy. Owing to the insensitivity to traditional therapy, targeted therapy becomes a possible alternative strategy. Over the past decade, the development of targeted treatments for metastatic RCC has advanced considerably. Several studies have shown that the vascular endothelial growth factor pathway is an important mediator for the occurrence and development of RCC, and tyrosine kinase inhibitors (TKIs) that target vascular endothelial growth factor receptors (VEGFRs) have been considered optimal therapeutic options for RCC. Six small molecules that inhibit VEGFR1/2/3, namely, sunitinib, sorafenib, axitinib, pazopanib, cabozantinib, and lenvatinib, have been approved by the Food and Drug Administration (FDA) for the treatment of RCC. Additionally, clinical trials assessing seven TKIs that target VEGFRs are currently in progress. To some extent, these drugs improve quality of life and prolong the survival of patients. This paper presents a review of the systemic targeted therapies against VEGFRs that have been approved so far or are undergoing trials as treatments for RCC.

Single-Molecule Super-Resolution Microscopy Reveals Heteromeric Complexes of MET and EGFR upon Ligand Activation

Receptor tyrosine kinases (RTKs) orchestrate cell motility and differentiation. Deregulated RTKs may promote cancer and are prime targets for specific inhibitors. Increasing evidence indicates that resistance to inhibitor treatment involves receptor cross-interactions circumventing inhibition of one RTK by activating alternative signaling pathways. Here, we used single-molecule super-resolution microscopy to simultaneously visualize single MET and epidermal growth factor receptor (EGFR) clusters in two cancer cell lines, HeLa and BT-20, in fixed and living cells. We found heteromeric receptor clusters of EGFR and MET in both cell types, promoted by ligand activation. Single-protein tracking experiments in living cells revealed that both MET and EGFR respond to their cognate as well as non-cognate ligands by slower diffusion. In summary, for the first time, we present static as well as dynamic evidence of the presence of heteromeric clusters of MET and EGFR on the cell membrane that correlates with the relative surface expression levels of the two receptors.

Efficacy and Prognostic Factors of Sunitinib as First-Line Therapy for Patients With Metastatic Renal Cell Carcinoma in an Arab Population

PURPOSE

Antiangiogenic tyrosine kinase inhibitors have been the mainstay first-line therapy for metastatic renal cell carcinoma (mRCC). We reviewed the efficacy of first-line therapy with sunitinib in patients with mRCC in an Arab population.

METHODS

Medical records of patients with mRCC treated at a tertiary care center in Saudi Arabia, during the period from 2007 to 2016, were reviewed. Demographic data, treatment received, response, and prognostic factors were analyzed.

RESULTS

Fifty-five patients who received sunitinib were identified. The median age was 60 years (range, 18 to 78 years), and 42 of the 55 patients were men (76.3%). International Metastatic RCC Diagnostic Consortium prognostic scores for favorable/intermediate/poor were 14.5%/43.6%/38.2%, respectively. The median performance status was 1, and the median Charlson comorbidity index score was 9. Thirty-seven patients (67.2%) had cytoreductive nephrectomy. Thirty-seven patients (67.2%) had clear cell histology. Twenty-two patients (40%) underwent dose reduction. Twenty-seven patients (49%) received second-line therapy, and seven patients (12.7%) received third-line therapy. Response rates were complete response in one patient (1.8%), partial response in 17 (30.9%), stable disease in 10 (18.1), and disease progression in 20 (36.3%). Progression-free survival (PFS) and overall survival (OS) were 6.0 and 24.7 months, respectively. Univariate analysis showed statistically improved PFS for dose reduction (P = .015) and the development of hypothyroidism (P = .03). It also showed statistically improved OS for dose reduction (P = .035), hypothyroidism (P = .0002), and cytoreductive nephrectomy (P = .0052). Multivariate analysis showed statistically improved PFS for dose reduction (P = .01) and OS for development of hypothyroidism (P = .007).

CONCLUSION

Our data for sunitinib in mRCC show significantly lower PFS than expected. The absence of prognostic value of the International Metastatic RCC Diagnostic Consortium scoring system and pathologic subtype warrant further investigation and possible inclusion of genetic scoring in this ethnic group of patients.

The Changing Landscape of Management of Metastatic Renal Cell Carcinoma: Current Treatment Options and Future Directions

OPINION STATEMENT

For the practicing clinician, the dilemma becomes how most appropriate to sequence the aforementioned regimens. It is challenging to be dogmatic, as there are no comparative studies juxtaposing novel front-line options directly-all of the available studies utilize a comparator arm of sunitinib. With this in mind, the selection of front-line therapy with a patient with mRCC should involve a thorough discussion of both efficacy and safety of available options. The oncologist must also weigh their ability to manage complex immune-related adverse events that can emerge from checkpoint inhibitors, particularly with dual regimens such as nivolumab/ipilimumab. For the patient with good-risk disease, VEGF-directed therapies should remain a component of treatment. The data from CheckMate-214 does not support the use of nivolumab/ipilimumab in this setting, and in fact suggests superiority with the approach of VEGF-TKIs. Until regulatory decisions have been made around bevacizumab/atezolizumab and axitinib/avelumab, sunitinib and pazopanib remain options for patients with good-risk disease, although cabozantinib should be a consideration as well. Although the CABOSUN study did not include patients with good-risk disease, it is important to bear in mind that this was more of a pragmatic decision-inclusion of these patients in the original design could have potentially lengthened the extent of necessary follow-up. From a mechanistic standpoint, there is no reason to assume that cabozantinib would not also achieve superiority to sunitinib in patients with good-risk disease. For patients with intermediate- and poor-risk disease, cabozantinib and nivolumab/ipilimumab represent the only reasonable options thus far that have achieved regulatory approval. As previously noted, nivolumab/ipilimumab has proven benefit in this setting, but should be used only by the oncologist who has ready access to subspecialists who can aid in managing immune-related adverse events. Prompt recognition of colitis, hepatitis, and other sequelae from these therapies is critical, as these toxicities can be life-threatening. If such resources are not available, then cabozantinib should be considered. Cabozantinib should further be contemplated in the subset of patients with bony metastatic disease, where it appears to offer substantial control. Of course, it also represents an option for those individuals who have contraindications to immunotherapy, such as rheumatologic and autoimmune disorders.When combinations of VEGF-directed and immunotherapies are approved, the clinician will have an even more complicated dilemma. Regimens such as a bevacizumab/atezolizumab offer an exceptional safety profile, which may weigh heavily in frail patients who cannot tolerate the side effect profile associated with VEGF-TKIs.

Efficacy of Dual Inhibition of Glycolysis and Glutaminolysis for Therapy of Renal Lesions in Tsc2+/- Mice

Tuberous sclerosis is caused by mutations in the TSC1 or TSC2 gene and characterized by development of tumors in multiple organs including the kidneys. TSC-associated tumors exhibit somatic loss of the second allele of the TSC genes, leading to aberrant activation of the mechanistic target of rapamycin (mTOR) signaling pathway. Activation of mTOR complex 1 (mTORC1) causes addiction to glucose and glutamine in Tsc1^−/−or Tsc2^−/− mouse embryonic fibroblasts (MEFs). Blocking of glutamine anaplerosis in combination with glycolytic inhibition causes significant cell death in Tsc2^−/− but not Tsc2^+/+ MEFs. In this study, we tested efficacy of dual inhibition of glycolysis with 3-BrPA and glutaminolysis with CB-839 for renal tumors in Tsc2^+/− mice. Following 2 months of treatment of Tsc2^+/− mice from the age of 12 months, combination of 3-BrPA and CB-839 significantly reduced overall size and cellular areas of all renal lesions (cystic/papillary adenomas and solid carcinomas), but neither alone did. Combination of 3-BrPA and CB-839 inhibited mTORC1 and the proliferation of tumor cells but did not increase apoptosis. However, combination of 3-BrPA and CB-839 was not as efficacious as rapamycin alone or rapamycin in combination with either 3-BrPA or CB-839 for renal lesions of Tsc2^+/− mice. Consistently, rapamycin alone or rapamycin in combination with either 3-BrPA or CB-839 had stronger inhibitory effects on mTORC1 and proliferation of tumor cells than combination of 3-BrPA and CB-839. We conclude that combination of 3-BRPA and CB-839 may not offer a better therapeutic strategy than rapamycin for TSC-associated tumors.

FLT3 inhibitors in acute myeloid leukemia

FLT3 mutations are one of the most common findings in acute myeloid leukemia (AML). FLT3 inhibitors have been in active clinical development. Midostaurin as the first-in-class FLT3 inhibitor has been approved for treatment of patients with FLT3-mutated AML. In this review, we summarized the preclinical and clinical studies on new FLT3 inhibitors, including sorafenib, lestaurtinib, sunitinib, tandutinib, quizartinib, midostaurin, gilteritinib, crenolanib, cabozantinib, Sel24-B489, G-749, AMG 925, TTT-3002, and FF-10101. New generation FLT3 inhibitors and combination therapies may overcome resistance to first-generation agents.

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.