Belzutifan for Renal Cell Carcinoma in von Hippel-Lindau Disease

Ophthalmologic toxicities of antineoplastic agents in genitourinary cancers: Mechanisms, management, and clinical implications

Genitourinary cancers affect over 480,000 patients in the United States annually. While promising therapeutic modalities continue to emerge, notably immune checkpoint inhibitors, molecular targeted therapies, antibody-drug conjugates, and radioligand therapies, these treatments are associated with a spectrum of adverse side-effects, including ophthalmologic toxicities. In this review, we cover the most commonly used antineoplastic agents for the kidneys, bladder, urinary tracts, prostate, testis, and penis, detailing mechanism, indication, and recent trials supporting their use. For each category of antineoplastic therapy, we describe the epidemiology, management, and clinical presentation, of common ophthalmologic toxicities stemming from these agents. This review serves to augment awareness and recognition of possible ophthalmologic manifestations resulting from the use of antineoplastic agents in genitourinary malignancy. Early identification of these side effects can hasten ophthalmology referral and ultimately improve visual outcomes in patients experiencing medication-induced ocular toxicities.

Neuroendocrine Tumors: Germline Genetics and Hereditary Syndromes

OPINION STATEMENT

The vast majority of neuroendocrine 'neoplasms (NENs) are sporadic, although recent evidence has indicated that a subset of these cancers may also originate as a result of genetic germline mutations. To date, 10% of these cancers can be linked to an inherited genetic syndrome. Genetic diagnosis is crucial for patients with a suspected hereditary NEN syndrome, as it recognizes patients carrying germline mutations and allows for personalized clinical follow-up, considering the higher risk of developing other tumours. The potential for early genetic detection has significant implications for the treatment of patients with hereditary NEN syndrome, as it may facilitate the delivery of precision therapy that differs from that typically provided to other patients. Thus, the integration of genotypic and phenotypic diagnostic methods help clinicians to provide more informed treatment and to extend appropriate prevention to family members.

HIF2α inhibits glutaminase clustering in mitochondria to sustain growth of clear cell Renal Cell Carcinoma

Clear cell renal cell carcinomas (ccRCC) are largely driven by HIF2α and are avid consumers of glutamine. However, inhibitors of glutaminase1 (GLS1), the first step in glutaminolysis, have not shown benefit in phase III trials, and HIF2α inhibition, recently FDA-approved for treatment of ccRCC, shows great but incomplete benefits, underscoring the need to better understand the roles of glutamine and HIF2α in ccRCC. Here, we report that glutamine deprivation rapidly redistributes GLS1 into isolated clusters within mitochondria across diverse cell types, but not in ccRCC. GLS1 clustering is rapid (1-3 hours) and reversible, is specifically driven by reduced intracellular glutamate, and is mediated by mitochondrial fission. Clustered GLS1 markedly enhances glutaminase activity and promotes cell death under glutamine-deprived conditions. HIF2α prevents GLS1 clustering, independently of its transcriptional activity, thereby protecting ccRCC cells from cell death induced by glutamine deprivation. Reversing this protection, by genetic expression of GLS1 mutants that constitutively cluster, enhances ccRCC cell death in culture and suppresses ccRCC growth in vivo . These findings provide multiple insights into cellular glutamine handling, including a novel metabolic pathway by which HIF2α promotes ccRCC, and reveals a potential therapeutic avenue to synergize with HIF2α inhibition in the treatment of ccRCC.

New Developments in VHL-Associated Neuroendocrine Neoplasms

PURPOSE OF REVIEW

The purpose of this review is to outline the current knowledge on epidemiology, diagnosis and management of neuroendocrine neoplasms (NENs) that develop in the context of Von Hippel-Lindau (VHL) syndrome.

RECENT FINDINGS

Pancreatic NENs develop in 8-17% of VHL patients (vPNENs) and are mostly multi-focal, cystic and non-functioning. Surgical resection is recommended for vPNENS > 3 cm that exhibit higher metastatic potential or in tumors with short doubling time while in the 20% of cases with metastatic disease the HIF-2 A inhibitor belzutifan is considered a promising option. Pheochromocytomas arising in VHL type 2 are often bilateral and have a noradrenergic phenotype while they are associated with increased risk of recurrence. High-specific activity [131I]-MIBG and sunitinib are the treatment options with the highest level of evidence whereas studies on belzutifan are evolving. Life-long surveillance and management in the context of a multidisciplinary team are suggested to achieve the best clinical outcome.

BELZUTIFAN FOR TREATMENT OF GIANT RETINAL HEMANGIOBLASTOMA WITH EXTRASCLERAL EXTENSION ASSOCIATED WITH VON HIPPEL-LINDAU SYNDROME

PURPOSE

To describe the clinical response and safety profile of the novel HIF-2ɑ inhibitor belzutifan in treating a giant retinal hemangioblastoma with extrascleral extension associated with von Hippel-Lindau syndrome.

METHODS

A 71-year-old woman with Von Hippel-Lindau syndrome presented with a giant retinal hemangioblastoma with extrascleral extension in her only remaining eye. She had no light perception in the right eye and intraocular pressure was 48. She requested enucleation because of chronic pain, but because of concern for significant bleeding given the size of the neoplasm, a trial of belzutifan was initiated.

RESULTS

Within 3 months of treatment initiation, the patient reported an 80% reduction in pain. Magnetic resonance imaging showed 30% reduction in longest tumor diameter. Dose adjustments were guided by serum hemoglobin levels, allowing the patient to remain on the medication for over a year with continued tumor regression on MRI and avoid enucleation.

CONCLUSION

Retinal hemangioblastoma with extrascleral extension is exceedingly rare and its treatment is complex, often requiring enucleation or external beam radiotherapy. This report demonstrates the use of belzutifan to safely and successfully reduce ocular tumor burden of complicated retinal hemangioblastoma with extrascleral extension, ultimately decreasing the need for enucleation.

Pediatric patients with von Hippel-Lindau and hemangioblastomas treated successfully with belzutifan

Hemangioblastoma is the most common tumor associated with von Hippel-Lindau (VHL), and are a leading cause of mortality. We present five pediatric patients with VHL-associated hemangioblastomas treated with belzutifan, a hypoxia-inducible factor 2a (HIF2a) inhibitor. Three patients were started on belzutifan due to vision loss from progressive retinal hemangioblastomas. Within one year of treatment, all three patients had improvement in hemangioblastoma size and visual acuity. For patients with intracranial lesions, belzutifan resulted in an improvement in neurologic symptoms and hemangioblastoma size. Four patients experienced grade 1-2 anemia and two patients required a dose reduction. Our report suggests that belzutifan can be an effective therapy for pediatric, adolescent, and young adult patients with VHL-associated hemangioblastomas.

The role of transcription factors in the crosstalk between cancer-associated fibroblasts and tumor cells

BACKGROUND

Transcription factors (TFs) fulfill a critical role in the formation and maintenance of different cell types during the developmental process as well as disease. It is believed that cancer-associated fibroblasts (CAFs) are activation status of tissue-resident fibroblasts or derived from form other cell types via transdifferentiation or dedifferentiation. Despite a subgroup of CAFs exhibit anti-cancer effects, most of them are reported to exert effects on tumor progression, further indicating their heterogeneous origin.

AIM OF REVIEW

This review aimed to summarize and review the roles of TFs in the reciprocal crosstalk between CAFs and tumor cells, discuss the emerging mechanisms, and their roles in cell-fate decision, cellular reprogramming and advancing our understanding of the gene regulatory networks over the period of cancer initiation and progression.

KEY SCIENTIFIC CONCEPTS OF REVIEW

This manuscript delves into the key contributory factors of TFs that are involved in activating CAFs and maintaining their unique states. Additionally, it explores how TFs play a pivotal and multifaceted role in the reciprocal crosstalk between CAFs and tumor cells. This includes their involvement in processes such as epithelial-mesenchymal transition (EMT), proliferation, invasion, and metastasis, as well as metabolic reprogramming. TFs also have a role in constructing an immunosuppressive microenvironment, inducing resistance to radiation and chemotherapy, facilitating angiogenesis, and even 'educating' CAFs to support the malignancies of tumor cells. Furthermore, this manuscript delves into the current status of TF-targeted therapy and considers the future directions of TFs in conjunction with anti-CAFs therapies to address the challenges in clinical cancer treatment.

Belzutifan plus cabozantinib as first-line treatment for patients with advanced clear-cell renal cell carcinoma (LITESPARK-003): an open-label, single-arm, phase 2 study

BACKGROUND

Belzutifan, a first-in-class HIF-2α inhibitor, has shown antitumour activity as monotherapy and in combination with cabozantinib in patients with previously treated advanced kidney cancer. The phase 2 LITESPARK-003 study was designed to determine the antitumour activity and safety of belzutifan in combination with cabozantinib in patients with advanced clear-cell renal cell carcinoma that was previously untreated (cohort 1) or previously treated with immunotherapy (cohort 2). Here, we report results from cohort 1 of this clinical trial.

METHODS

LITESPARK-003 is an open-label, single-arm, phase 2 study at ten hospitals and cancer centres in the USA. In cohort 1, eligible patients were at least 18 years of age, had an Eastern Cooperative Oncology Group performance status of 0 or 1, and had received no previous systemic therapy for locally advanced or metastatic renal cell carcinoma. Patients received belzutifan 120 mg orally once daily and cabozantinib 60 mg orally once daily until unacceptable adverse events, disease progression, or patient withdrawal. The primary endpoint was investigator-assessed confirmed objective response according to Response Evaluation Criteria in Solid Tumors version 1.1. Antitumour activity and safety were assessed in all patients who received at least one dose of study treatment. This trial is registered with ClinicalTrials.gov, NCT03634540, and is ongoing.

FINDINGS

Between Sept 27, 2018, and Jan 10, 2023, we screened 138 patients for eligibility, and 50 (36%) were enrolled and assigned to cohort 1. The median age was 64 years (IQR 57-72). 40 (80%) of 50 patients were male and ten (20%) were female. 48 (96%) patients were White, one (2%) patient was Black or African American, and one (2%) was of a race in the other category. As of the data cutoff (May 15, 2023), median follow-up was 24·3 months (IQR 13·9-32·0). 35 (70%, 95% CI 55-82) of 50 patients had a confirmed objective response, including four (8%) who had a complete response and 31 (62%) who had a partial response. The most frequent grade 3-4 treatment-related adverse events were hypertension (six [12%] patients), anaemia (five [10%] patients), and fatigue (four [8%] patients). Seven (14%) of 50 patients had serious treatment-related adverse events. No treatment-related deaths occurred.

INTERPRETATION

Belzutifan plus cabozantinib has promising antitumour activity in treatment-naive patients with advanced clear-cell renal cell carcinoma and further investigation of an HIF-2α inhibitor in combination with a multitargeted tyrosine kinase inhibitor as a treatment option in this population is warranted.

FUNDING

Merck Sharp & Dohme LLC, a subsidiary of Merck & Co, Inc, Rahway, NJ, USA, and the National Cancer Institute.

Predominantly multiple focal non-cystic renal lesions: an imaging approach

Multiple non-cystic renal lesions are occasionally discovered during imaging for various reasons and poses a diagnostic challenge to the practicing radiologist. These lesions may appear as a primary or dominant imaging finding or may be an additional abnormality in the setting of multiorgan involvement. Awareness of the imaging appearance of the various entities presenting as renal lesions integrated with associated extrarenal imaging findings along with clinical information is crucial for a proper diagnostic approach and patient work-up. This review summarizes the most relevant causes of infectious, inflammatory, vascular, and neoplastic disorders presenting as predominantly multiple focal non-cystic lesions.

Advancements in understanding the molecular mechanisms and clinical implications of Von Hippel-Lindau syndrome: A comprehensive review

Von Hippel-Lindau Syndrome (VHL) is a rare genetic disorder characterized by tumors in multiple organs, including the kidneys, pancreas, and central nervous system. This comprehensive review discusses the genetic basis and clinical manifestations of VHL, as well as recent advancements in understanding the molecular mechanisms that lead to tumor formation. The authors highlight the role of hypoxia-inducible factors and the ubiquitin-proteasome system in VHL-associated cancer development .The review also discusses the potential clinical implications of these findings, such as the development of targeted therapies for VHL-associated cancers. However, the authors note the challenges associated with developing effective treatments for this complex disease, including limited patient availability for clinical trials due to its rarity .Overall, this review provides valuable insights into our current understanding of VHL and offers important avenues for future research aimed at improving the diagnosis, treatment, and management of VHL patients. By illuminating the molecular underpinnings of VHL-associated cancers, this work may ultimately help to develop more effective treatments and improve outcomes for patients with this challenging disease.

The interplay between the tumor microenvironment and tumor-derived small extracellular vesicles in cancer development and therapeutic response

The tumor microenvironment (TME) plays an essential role in tumor cell survival by profoundly influencing their proliferation, metastasis, immune evasion, and resistance to treatment. Extracellular vesicles (EVs) are small particles released by all cell types and often reflect the state of their parental cells and modulate other cells' functions through the various cargo they transport. Tumor-derived small EVs (TDSEVs) can transport specific proteins, nucleic acids and lipids tailored to propagate tumor signals and establish a favorable TME. Thus, the TME's biological characteristics can affect TDSEV heterogeneity, and this interplay can amplify tumor growth, dissemination, and resistance to therapy. This review discusses the interplay between TME and TDSEVs based on their biological characteristics and summarizes strategies for targeting cancer cells. Additionally, it reviews the current issues and challenges in this field to offer fresh insights into comprehending tumor development mechanisms and exploring innovative clinical applications.

The efficacy and safety of belzutifan inhibitor in patients with advanced or metastatic clear cell renal cell carcinoma: a meta-analysis

BACKGROUND

The belzutifan is a hypoxia inducible factor-2 alpha (HIF-2α) inhibitor for the treatment of advanced or metastatic clear cell renal cell carcinoma (mccRCC) and has exhibited good safety and efficacy in clinical trials. We conducted a meta-analysis of relevant studies to further clarify the efficacy and safety of belzutifan for the treatment of mccRCC.

METHODS

Multiple databases and abstracts from major scientific meetings were systematically reviewed for eligible articles published before June 1, 2024. The following outcomes were analyzed: objective response rate (ORR), disease control rate (DCR), median duration of response (mDOR), median progression-free survival (mPFS), median overall survival (mOS), and treatment-related adverse events (TRAes). 426 records were reviewed, and data were extracted by at least two individuals.

RESULTS

Seven studies involving 715 patients were included in this meta-analysis. The pooled ORR was 34% (95% confidence interval [CI]: 23-46%), the DCR was 79% (95% CI: 66-90%), the mDOR was 21.8 months (95% CI: 14.82-28.78), and the mPFS time was 8.8 months (95% CI: 6.15-11.44). The pooled incidence of grade 3-5 TRAes was 46%, and the most common TRAe was anemia. Further subgroup analysis revealed that, compared with belzutifan monotherapy, the combination of belzutifan with tyrosine kinase inhibitors (TKIs) as second- or later-line therapy was associated with a statistically significant increase in the ORR. Toxicity was also greater with combined inhibition therapy.

CONCLUSIONS

Our meta-analysis revealed moderate antitumor activity and a manageable safety profile of the inhibitor belzutifan in patients with mccRCC.

Targeting HIF-2α: the role of belzutifan in clear cell renal carcinoma management

INTRODUCTION

Belzutifan is a first-in-class hypoxia-inducible factor-2 alpha (HIF-2α) inhibitor. It targets the von Hippel-Lindau protein (pVHL)-HIF-vascular endothelial growth factor (VEGF) pathway, which is crucial in cellular responses to hypoxia. By inhibiting HIF-2α, belzutifan disrupts the transcription of genes involved in tumor growth and angiogenesis.

AREAS COVERED

In this review, we describe the pVHL-HIF-VEGF pathway and how it led to the development of HIF inhibitors, including belzutifan. A search was conducted for trials involving Belzutifan, including phase I-III trials. We describe the relevant toxicity, with emphasis on hypoxia and anemia.

EXPERT OPINION

Belzutifan is a relatively safe drug, with manageable adverse events, including anemia and hypoxia as on-target toxicity. Ongoing trials are studying its benefit in overall survival for RCC in first-line treatment and its potential in other malignancies. The LITESPARK-005 trial reported the benefit of belzutifan in progression-free survival (PFS) compared to everolimus in later lines of treatment, with improvement in quality-of-life outcomes. Given its different mechanism of action to currently available treatments, belzutifan is expected to play a prominent role in the treatment of clear cell renal carcinoma and other cancers.

Cluster Headache and Hypoxia: Breathing New Life into an Old Theory, with Novel Implications

Cluster headache is a severe, poorly understood disorder for which there are as yet virtually no rationally derived treatments. Here, Lee Kudrow's 1983 theory, that cluster headache is an overly zealous response to hypoxia, is updated according to current understandings of hypoxia detection, signaling, and sensitization. It is shown that the distinctive clinical characteristics of cluster headache (circadian timing of attacks and circannual patterning of bouts, autonomic symptoms, and agitation), risk factors (cigarette smoking; male gender), triggers (alcohol; nitroglycerin), genetic findings (GWAS studies), anatomical substrate (paraventricular nucleus of the hypothalamus, solitary tract nucleus/NTS, and trigeminal nucleus caudalis), neurochemical features (elevated levels of galectin-3, nitric oxide, tyramine, and tryptamine), and responsiveness to treatments (verapamil, lithium, melatonin, prednisone, oxygen, and histamine desensitization) can all be understood in terms of hypoxic signaling. Novel treatment directions are hypothesized, including repurposing pharmacological antagonists of hypoxic signaling molecules (HIF-2; P2X3) for cluster headache, breath training, physical exercise, high-dose thiamine, carnosine, and the flavonoid kaempferol. The limits of current knowledge are described, and a program of basic and translational research is proposed.

Pharmacological inhibition of HIF2 protects against bone loss in an experimental model of estrogen deficiency

Estrogen deficiency, which is linked to various pathological conditions such as primary ovarian insufficiency and postmenopausal osteoporosis, disrupts the delicate balance between bone formation and resorption. This imbalance leads to bone loss and an increased risk of fractures, primarily due to a significant reduction in trabecular bone mass. Trabecular osteoblasts, the cells responsible for bone formation within the trabecular compartment, originate from skeletal progenitors located in the bone marrow. The microenvironment of the bone marrow contains hypoxic (low oxygen) regions, and the hypoxia-inducible factor-2α (HIF2) plays a crucial role in cellular responses to these low-oxygen conditions. This study demonstrates that the loss of HIF2 in skeletal progenitors and their derivatives during development enhances trabecular bone mass by promoting bone formation. More importantly, PT2399, a small molecule that specifically inhibits HIF2, effectively prevents trabecular bone loss in ovariectomized adult mice, a model for estrogen-deficient bone loss. Both the genetic and pharmacological approaches result in an increase in osteoblast number, which is linked to the expansion of the pool of skeletal progenitor cells. This expansion either by loss or inhibition of HIF2 uncovers a pivotal mechanism for increasing osteoblast numbers and bone formation, resulting in greater trabecular bone mass.

Targeting Hypoxia and Autophagy Inhibition via Delivering Sonodynamic Nanoparticles With HIF-2α Inhibitor for Enhancing Immunotherapy in Renal Cell Carcinoma

Immune checkpoint blockers (ICBs) therapy stands as the first-line treatment option for advanced renal cell carcinoma (RCC). However, its effectiveness is hindered by the immunosuppressive tumor microenvironment (TME). Sonodynamic therapy (SDT) generates tumor cell fragments that can prime the host's antitumor immunity. Nevertheless, the hypoxic microenvironment and upregulated autophagy following SDT often lead to cancer cell resistance. In response to these challenges, a hypoxia-responsive polymer (Poly(4,4'-azobisbenzenemethanol-PMDA)-mPEG5k, P-APm) encapsulating both a HIF-2α inhibitor (belzutifan) and the ultrasonic sensitize (Chlorin e6, Ce6) is designed, to create the nanoparticle APm/Ce6/HIF. APm/Ce6/HIF combined with ultrasound (US) significantly suppresses tumor growth and activates antitumor immunity in vivo. Moreover, this treatment effectively transforms the immunosuppressive microenvironment from "immune-cold" to "immune-hot", thereby enhancing the response to ICBs therapy. The findings indicate that APm/Ce6/HIF offers a synergistic approach combining targeted therapy with immunotherapy, providing new possibilities for treating RCC.

Randomized phase II dose comparison LITESPARK-013 study of belzutifan in patients with advanced clear cell renal cell carcinoma

BACKGROUND

Belzutifan is a first-in-class hypoxia-inducible factor subunit 2α (HIF-2α) inhibitor approved at a dose of 120 mg once daily for certain adults with VHL disease and adults with advanced renal cell carcinoma (RCC) following therapy with a programmed cell death protein 1 (PD-1) [or programmed death ligand 1 (PD-L1)] inhibitor and a vascular endothelial growth factor tyrosine kinase inhibitor. However, whether the belzutifan dose could be optimized is unclear.

PATIENTS AND METHODS

The phase II LITESPARK-013 study (NCT04489771) enrolled patients with advanced clear cell RCC whose disease progressed after one to three prior systemic therapies, including an anti-PD-(L)1 regimen. Patients were randomly assigned 1 : 1 to receive belzutifan 120 or 200 mg once daily. The primary endpoint was the objective response rate (ORR) per RECIST version 1.1. The secondary endpoints were duration of response (DOR), progression-free survival (PFS), overall survival (OS), and safety.

RESULTS

Overall, 154 patients were enrolled (120 mg: n = 76; 200 mg: n = 78). The median follow-up was 20.1 months (range 14.8-28.4). The ORR was 23.7% versus 23.1% for the 120 mg and 200 mg groups, respectively [P = 0.5312; -0.5%, 95% confidence interval (CI) -14.0% to 12.9%]. The median DOR was not reached for the 120 mg arm and was 16.1 months (2.1+ to 23.5+) for the 200 mg arm. No between-group differences were observed for PFS [hazard ratio (HR) 0.94, 95% CI 0.63-1.40] or OS (medians not reached; HR 1.11, 95% CI 0.65-1.90). Grade 3 or 4 treatment-related adverse events were observed in 35 patients (46.1%) in the 120 mg group and 36 patients (46.2%) in the 200 mg group.

CONCLUSIONS

The efficacy of belzutifan was similar between the 120 mg dose and the 200 mg dose for previously treated clear cell RCC. Safety at both doses was consistent with the known safety profile of belzutifan. These results further support 120 mg once daily as the preferred dose for belzutifan.

Perspective review: lessons from successful clinical trials and real-world studies of systemic therapy for metastatic pheochromocytomas and paragangliomas

Pheochromocytomas and paragangliomas (PPGLs) are orphan tumors with the potential to spread to distant organs such as the lymph nodes, the skeleton, the lungs, and the liver. These metastatic tumors exhibit high rates of morbidity and mortality due to their frequently large tumor burden, the progression of the disease, and the excessive secretion of catecholamines that lead to cardiovascular disease and gastrointestinal dysmotility. Several molecular drivers responsible for the development of PPGLs have been described over the last 30 years. Although therapeutic options are limited, substantial progress has been made in the recognition of effective systemic therapies for these tumors. Successful clinical trials with radiopharmaceuticals such as high-specific-activity meta-iodobenzylguanidine and tyrosine kinase inhibitors such as cabozantinib and sunitinib have been recently published. This review will discuss the results of these studies and their impact on current clinical practices. In addition, this review will provide valuable information on how to design clinical trials to treat patients with metastatic PPGLs with novel medications.

Extrinsic and Cell-Intrinsic Stress in the Immune Tumor Micro-Environment

In continuously progressive tumor tissues, the causes of cellular stress are multiple: metabolic alterations, nutrient deprivation, chronic inflammation and hypoxia. To survive, tumor cells activate the stress response program, a highly conserved molecular reprogramming proposed to cope with challenges in a hostile environment. Not only cancer cells are affected, but stress responses in tumors also have a profound impact on their normal cellular counterparts: fibroblasts, endothelial cells and infiltrating immune cells. In recent years, there has been a growing interest in the interaction between cancer and immune cells, especially in difficult conditions of cellular stress. A growing literature indicates that knowledge of the molecular pathways activated in tumor and immune cells under stress conditions may offer new insights for possible therapeutic interventions. Counter-regulating the stress caused by the presence of a growing tumor can therefore be a weapon to limit disease progression. Here, we review the main pathways activated in cellular stress responses with a focus on immune cells present in the tumor microenvironment.

First and Second-line Treatments in Metastatic Renal Cell Carcinoma

BACKGROUND AND OBJECTIVE

The treatment landscape for metastatic renal cell carcinoma (mRCC) has evolved significantly in recent years, leading to improved outcomes. The aim of this review is to provide clinicians with a practical guide for selecting first- and second-line treatments on the basis of current evidence.

METHODS

We critically evaluated systemic treatment strategies for mRCC. A comprehensive literature search was conducted in PubMed and Embase, alongside manual searches of guidelines and conference proceedings up to October 2024. A narrative review was performed to reach a consensus, with voting used to resolve differing opinions among authors.

KEY FINDINGS AND LIMITATIONS

First-line treatment options include immune checkpoint inhibitor (ICI)-based combinations or tyrosine kinase inhibitors (TKIs). Four combination regimens have been approved internationally. Owing to the lack of head-to-head trials and standardized biomarkers, treatment decisions rely on factors such as International Metastatic RCC Database Consortium (IMDC) risk score, functional status, safety profiles, sarcomatoid features, use of immunosuppressive drugs, and need for immediate response. Despite advances, many patients will experience disease progression on ICI-based therapy, necessitating further treatment. The need for standardized second-line approaches remains unmet. TKIs, alone or with everolimus, show promising efficacy, while HIF2a inhibitors offer newer options with a favorable toxicity profile. Rechallenge with ICIs after early progression is not recommended.

CONCLUSIONS AND CLINICAL IMPLICATIONS

For optimal mRCC treatment selection, clinicians must carefully balance efficacy, toxicity, and patient preferences, especially when transitioning between first- and second-line therapies, to provide individualized care.

Myocarditis Following Pembrolizumab Plus Axitinib, and Belzutifan Plus Lenvatinib for Renal Cell Carcinoma: A Case Report

Cardiac toxicity is an adverse event of several classes of anti-cancer drugs. Herein, we present the case of a 52-year-old woman with metastatic renal cell carcinoma (RCC), previously treated with debulking surgery, pembrolizumab (immune checkpoint inhibitor) in combination with axitinib (tyrosine kinase inhibitor (TKI)), followed by lenvatinib (TKI) and belzutifan (HIF-2α inhibitor), who developed myocarditis proven by cardiac magnetic resonance and endomyocardial biopsy. The case was notable for reporting a not-yet described adverse event during treatment with belzutifan plus lenvatinib, the etiology of which was of unobvious determination given the pre-exposure to pembrolizumab, a known cause of drug-related myocarditis. We surmise that myocarditis was a delayed adverse event related to pembrolizumab (8 months after treatment interruption), although we emphasize that only attentive monitoring of cardiac adverse events of patients exposed to belzutifan and lenvatinib in the context of large clinical trials may rule out any causal implication of these drugs.

Oral Hypoxia-Inducible Factor 2α Inhibitor Belzutifan in Ocular von Hippel-Lindau Disease: Subgroup Analysis of the Single-Arm Phase 2 LITESPARK-004 Study

PURPOSE

To report the efficacy of the oral hypoxia-inducible factor 2α inhibitor belzutifan in participants with von Hippel-Lindau disease-associated retinal hemangioblastomas in the LITESPARK-004 study.

DESIGN

Subgroup analysis of the phase 2, single-arm, open-label LITESPARK-004 study.

PARTICIPANTS

Adults with 1 or more von Hippel-Lindau disease-associated measurable renal cell carcinoma tumors not requiring immediate surgical intervention were eligible.

METHODS

Participants received oral belzutifan 120 mg once daily until disease progression or unacceptable treatment-related toxicity.

MAIN OUTCOME MEASURES

Efficacy of belzutifan in retinal hemangioblastomas was a secondary end point, measured as response (improved, stable, or progressed) by independent reading center-certified graders based on color fundus imaging performed every 12 weeks using the investigator's preferred imaging standards. Additional assessments, where available, included OCT and ultra-widefield fluorescein angiography.

RESULTS

Among 61 participants in LITESPARK-004, 12 had 1 or more evaluable active retinal hemangioblastomas in 16 eyes at baseline per independent reading center. As of April 1, 2022, the median follow-up for participants with ocular von Hippel-Lindau disease at baseline was 37.3 months. All 16 eyes were graded as improved, with a response rate of 100.0% (95% confidence interval, 79.4%-100%). No new retinal hemangioblastomas or ocular disease progression were reported as of data cutoff date. Eight participants underwent additional multimodal eye assessments performed at the National Institutes of Health study site. Among this subgroup, 10 of 24 hemangioblastomas in 8 eyes of 6 participants measured 500 μm or more in greatest linear dimension at baseline and were analyzed further. All 10 hemangioblastomas had a mean area reduction of 15% or more by month 12 and of 30% or more by month 24.

CONCLUSIONS

Belzutifan showed promising activity against ocular von Hippel-Lindau disease, including capacity to control retinal hemangioblastomas, with effects sustained for more than 2 years while treatment is ongoing.

FINANCIAL DISCLOSURE(S)

Proprietary or commercial disclosure may be found in the Footnotes and Disclosures at the end of this article.

Successful Targeting of Somatic VHL Alterations With Belzutifan in Two Cases

Clear cell renal cell carcinoma (RCC) is commonly associated with alterations in the VHL tumor suppressor gene, resulting in upregulation of hypoxia-inducible factor pathways. Immune checkpoint inhibitors and vascular endothelial growth factor inhibitors are the mainstays of systemic treatment for metastatic RCC; however, most patients encounter disease progression after the initial response. The phase 3 clinical trial LITESPARK-005-belzutifan (HIF-2α inhibitor) demonstrated improvement in progression-free survival compared with everolimus in heavily pretreated patients unselected for somatic/germline VHL alterations (an objective response rate of 23% and a median time on therapy of 7.6 months in the belzutifan cohort), resulting in U.S. FDA approval for patients with advanced RCC. Herein, we present two cases of refractory metastatic RCC (including one with brain metastases) with somatic VHL mutations who received belzutifan after discussion in the institutional Molecular Tumor Board. Both patients had an excellent clinical response (partial remissions ongoing at >12 and >20 months). Future studies should assess the merits of biomarker selection for belzutifan treatment.

Oxygen-sensing pathways and the pulmonary circulation

The unique property of the pulmonary circulation to constrict in response to hypoxia, rather than dilate, brings advantages in both health and disease. Hypoxic pulmonary vasoconstriction (HPV) acts to optimise ventilation-perfusion matching - this is important clinically both in focal disease (such as pneumonia) and in one-lung ventilation during anaesthesia for thoracic surgery. However, during global hypoxia such as that encountered at high altitude, generalised pulmonary vasoconstriction can lead to pulmonary hypertension. There is now a growing body of evidence that links the hypoxia-inducible factor (HIF) pathway and pulmonary vascular tone - in both acute and chronic settings. Genetic and pharmacological alterations to all key components of this pathway (VHL - von Hippel-Lindau ubiquitin E3 ligase; PHD2 - prolyl hydroxylase domain protein 2; HIF1 and HIF2) have clear effects on the pulmonary circulation, particularly in hypoxia. Furthermore, knowledge of the molecular biology of the prolyl hydroxylase enzymes has led to an extensive and ongoing body of research into the importance of iron in both HPV and pulmonary hypertension. This review will explore these relationships in more detail and discuss future avenues of research.

[Genetics in nephrology - any news?]

While genetic kidney diseases were long regarded as a rare cause of kidney failure, it has been shown in recent years that they account for a relevant proportion of cases. In cohorts of kidney transplant recipients, a monogenic cause is found in up to 30% of cases. Identifying the genetic cause of kidney disease has become much easier thanks to technological advances in DNA sequencing. The focus has now shifted to understanding the significance of the findings and identifying diagnostic gaps. It is still not possible to clarify all CKD cases of unclear aetiology. Besides very effective generic treatments for monogenic kidney disease (e.g., ACE-inhibitor use in Alport Syndrome), increasing knowledge of the pathophysiology of genetic kidney diseases has led to a growing number of targeted therapies. These include the treatment of ADPKD with Tolvaptan, which has now been in use for 10 years. Recently, exciting, and completely new approaches have been added, such as the first siRNA therapies in nephrology for primary hyperoxaluria type 1, the targeted treatment of hyperphagia in Bardet-Biedl syndrome, the therapy of APOL1-associated kidney disease or the use of the HIF-2 antagonist Belzutifan for renal cell carcinoma associated with Von-Hippel-Lindau syndrome. The new possibilities in the treatment of patients with genetic kidney diseases have also clearly revealed deficits in current patient care. Centers of excellence with extensive experience in this area therefore play an important role in improving care. This also applies to the further training of colleagues in the field. In Germany, the National Action Alliance for People with Rare Diseases (NAMSE) and the nationwide establishment of - to date - 36 centers for rare diseases play an important role in this regard.

French AFU Cancer Committee Guidelines - Update 2024-2026: Management of kidney cancer

OBJECTIVE

To update the French recommendations for the management of kidney cancer.

METHODS

A systematic review of the literature was conducted for the period from 2014 to 2024. The most relevant articles concerning the diagnosis, classification, surgical treatment, medical treatment, and follow-up of kidney cancer were selected and incorporated into the recommendations. The recommendations have been updated specifying the level of evidence (strong or weak).

RESULTS

Kidney cancer following prolonged occupational exposure to trichloroethylene should be considered an occupational disease. The reference examination for the diagnosis and staging of kidney cancer is the contrast-enhanced thoraco-abdominal CT scan. PET scans are not indicated in the staging of kidney cancer. Percutaneous biopsy is recommended in situations where its results will influence therapeutic decisions. It should be used to reduce the number of surgeries for benign tumors, particularly avoiding unnecessary radical nephrectomies. Kidney tumors should be classified according to the pTNM 2017 classification, the WHO 2022 classification, and the ISUP nucleolar grade. Metastatic kidney cancers should be classified according to IMDC criteria. Surveillance of tumors smaller than 2cm should be prioritized and can be offered regardless of patient age. Robot-assisted laparoscopic partial nephrectomy is the reference surgical treatment for T1 tumors. Ablative therapies and surveillance are options for elderly patients with comorbidities for tumors larger than 2cm. Stereotactic radiotherapy is an option to discuss for treating localized kidney tumors in patients not eligible for other treatments. Radical nephrectomy is the first-line treatment for locally advanced localized cancers. Pembrolizumab is recommended for patients at high risk of recurrence after surgery for localized kidney cancer. In metastatic patients, cytoreductive nephrectomy can be immediate in cases of good prognosis, delayed in cases of intermediate or poor prognosis for patients stabilized by medical treatment, or as "consolidation" in patients with complete or major partial response at metastatic sites after systemic treatment. Surgical or local treatment of metastases can be proposed for single lesions or oligometastases. Recommended first-line drugs for metastatic clear cell renal carcinoma are combinations of axitinib/pembrolizumab, nivolumab/ipilimumab, nivolumab/cabozantinib, and lenvatinib/pembrolizumab. Patients with non-clear cell metastatic kidney cancer should be presented to the CARARE Network and prioritized for inclusion in clinical trials.

CONCLUSION

These updated recommendations are a reference that will enable French and French-speaking practitioners to optimize their management of kidney cancer.

Von Hippel-Lindau protein signalling in clear cell renal cell carcinoma

The distinct pathological and molecular features of kidney cancer in adaptation to oxygen homeostasis render this malignancy an attractive model for investigating hypoxia signalling and potentially developing potent targeted therapies. Hypoxia signalling has a pivotal role in kidney cancer, particularly within the most prevalent subtype, known as renal cell carcinoma (RCC). Hypoxia promotes various crucial pathological processes, such as hypoxia-inducible factor (HIF) activation, angiogenesis, proliferation, metabolic reprogramming and drug resistance, all of which contribute to kidney cancer development, growth or metastasis formation. A substantial portion of kidney cancers, in particular clear cell RCC (ccRCC), are characterized by a loss of function of Von Hippel-Lindau tumour suppressor (VHL), leading to the accumulation of HIF proteins, especially HIF2α, a crucial driver of ccRCC. Thus, therapeutic strategies targeting pVHL-HIF signalling have been explored in ccRCC, culminating in the successful development of HIF2α-specific antagonists such as belzutifan (PT2977), an FDA-approved drug to treat VHL-associated diseases including advanced-stage ccRCC. An increased understanding of hypoxia signalling in kidney cancer came from the discovery of novel VHL protein (pVHL) targets, and mechanisms of synthetic lethality with VHL mutations. These breakthroughs can pave the way for the development of innovative and potent combination therapies in kidney cancer.

Gating residues govern ligand unbinding kinetics from the buried cavity in HIF-2α PAS-B

While transcription factors have been generally perceived as "undruggable," an exception is the HIF-2 hypoxia-inducible transcription factor, which contains an internal cavity that is sufficiently large to accommodate a range of small-molecules, including the therapeutically used inhibitor belzutifan. Given the relatively long ligand residence times of these small molecules and the lack of any experimentally observed pathway connecting the cavity to solvent, there has been great interest in understanding how these drug ligands exit the buried receptor cavity. Here, we focus on the relevant PAS-B domain of hypoxia-inducible factor 2α (HIF-2α) and examine how one such small molecule (THS-017) exits from the buried cavity within this domain on the seconds-timescale using atomistic simulations and ZZ-exchange NMR. To enable the simulations, we applied the weighted ensemble path sampling strategy, which generates continuous pathways for a rare-event process [e.g., ligand (un)binding] with rigorous kinetics in orders of magnitude less computing time compared to conventional simulations. Results reveal the formation of an encounter complex intermediate and two distinct classes of pathways for ligand exit. Based on these pathways, we identified two pairs of conformational gating residues in the receptor: one for the major class (N288 and S304) and another for the minor class (L272 and M309). ZZ-exchange NMR validated the kinetic importance of N288 for ligand unbinding. Our results provide an ideal simulation dataset for rational manipulation of ligand unbinding kinetics.

Somatostatin receptor 2A expression in von Hippel-Lindau-related hemangioblastomas

BACKGROUND

Central nervous system hemangioblastomas are the most prevalent manifestation of von Hippel-Lindau (VHL) disease and remain the main cause of mortality. Surgical resection is the primary treatment strategy, but is not always possible, and should be used as restrictively as possible. There is an unmet need for less invasive treatment strategies, such as targeted therapy. Expression of somatostatin receptor 2A (SSTR2A) in VHL-related hemangioblastomas has been described earlier, but the extent of expression in a larger population has yet to be determined. The authors hypothesize that a substantial subset of VHL-related hemangioblastomas show SSTR2A expression, which may serve as a potential new treatment target.

METHODS

Patients who were surgically treated for a VHL-related hemangioblastoma from 1990 until 2021 at the UMC Utrecht were included. Clinical data was derived from a clinical database. Tissue samples were histopathologically examined with use of hematoxylin and eosin staining, and immunohistochemical analysis of SSTR2A expression was performed.

RESULTS

Forty-three tissue samples were obtained from 26 patients. Nine showed strong positivity for SSTR2A expression, whereas 13 showed moderate and 15 sparse expression. Three samples showed no expression of SSTR2A. The distribution showed right-skewedness favoring a strong expression. SSTR2A expression colocalized with endothelial markers and not with stromal cells. Additionally, within-patient variability for SSTR2A expression was described in 14 patients.

CONCLUSION

SSTR2A is expressed in varying degrees in the majority of VHL-related hemangioblastomas. Future treatment with somatostatin analogues or even peptide receptor radionuclide treatment may be considered for SSTR2A-positive cases.

USP7 depletion potentiates HIF2α degradation and inhibits clear cell renal cell carcinoma progression

Clear cell renal cell carcinoma (ccRCC) is characterized by Von Hippel Lindau (VHL) gene loss of function mutation, which leads to the accumulation of hypoxia-inducible factor 2α (HIF2α). HIF2α has been well-established as one of the major oncogenic drivers of ccRCC, however, its therapeutic targeting remains a challenge. Through an analysis of proteomic data from ccRCCs and adjacent non-tumor tissues, we herein revealed that Ubiquitin-Specific Peptidase 7 (USP7) was upregulated in tumor tissues, and its depletion by inhibitors or shRNAs caused significant suppression of tumor progression in vitro and in vivo. Mechanistically, USP7 expression is activated by the transcription factors FUBP1 and FUBP3, and it promotes tumor progression mainly by deubiquitinating and stabilizing HIF2α. Moreover, the combination of USP7 inhibitors and afatinib (an ERBB family inhibitor) coordinately induce cell death and tumor suppression. In mechanism, afatinib indirectly inhibits USP7 transcription and accelerates the degradation of HIF2α protein, and the combination of them caused a more profound suppression of HIF2α abundance. These findings reveal a FUBPs-USP7-HIF2α regulatory axis that underlies the progression of ccRCC and provides a rationale for therapeutic targeting of oncogenic HIF2α via combinational treatment of USP7 inhibitor and afatinib.

Molecular Basis of Pancreatic Neuroendocrine Tumors

Pancreatic neuroendocrine tumors (NETs) are rare well-differentiated neoplasms with limited therapeutic options and unknown cells of origin. The current classification of pancreatic neuroendocrine tumors is based on proliferative grading, and guides therapeutic strategies, however, tumors within grades exhibit profound heterogeneity in clinical manifestation and outcome. Manifold studies have highlighted intra-patient differences in tumors at the genetic and transcriptomic levels. Molecular classification might become an alternative or complementary basis for treatment decisions and reflect tumor biology, actionable cellular processes. Here, we provide a comprehensive review of genomic, transcriptomic, proteomic and epigenomic studies of pancreatic NETs to elucidate patterns shared between proposed subtypes that could form a foundation for new classification. We denote four NET subtypes with distinct molecular features, which were consistently reproduced using various omics technologies.

Emerging innovative treatment strategies for advanced clear cell renal cell carcinoma

Dramatic advances in biological discoveries, since the 1990s, have continued to reshape the treatment paradigm of metastatic renal cell carcinoma (RCC). Von Hippel Lindau (VHL) gene alterations are associated with pro-angiogenic activity and are central to the pathogenesis of clear cell RCC (ccRCC), the most predominant histologic subtype of RCC. Antiangiogenic strategies revolving around this VHL/HIF/VEGF axis have been shown to improve survival in metastatic ccRCC. The discovery of immune checkpoints and agents that target their inhibition introduced a new treatment paradigm for patients with RCC. While initially approved as monotherapy, studies investigating immune checkpoint inhibitor combinations have led to their approval as the new standard of care, providing durable responses and unprecedented improvements in clinical outcome. Despite these advances, the projected 14 390 deaths in 2024 from RCC underscore the need to continue efforts in expanding and optimizing treatment options for patients with metastatic RCC. This article reviews key findings that have transformed the way we understand and treat metastatic RCC, in addition to highlighting novel treatment strategies that are currently under development.

Toward a CRISPR-based mouse model of Vhl-deficient clear cell kidney cancer: Initial experience and lessons learned

CRISPR is revolutionizing the ability to do somatic gene editing in mice for the purpose of creating new cancer models. Inactivation of the VHL tumor suppressor gene is the signature initiating event in the most common form of kidney cancer, clear cell renal cell carcinoma (ccRCC). Such tumors are usually driven by the excessive HIF2 activity that arises when the VHL gene product, pVHL, is defective. Given the pressing need for a robust immunocompetent mouse model of human ccRCC, we directly injected adenovirus-associated viruses (AAVs) encoding sgRNAs against VHL and other known/suspected ccRCC tumor suppressor genes into the kidneys of C57BL/6 mice under conditions where Cas9 was under the control of one of two different kidney-specific promoters (Cdh16 or Pax8) to induce kidney tumors. An AAV targeting Vhl, Pbrm1, Keap1, and Tsc1 reproducibly caused macroscopic ccRCCs that partially resembled human ccRCC tumors with respect to transcriptome and cell of origin and responded to a ccRCC standard-of-care agent, axitinib. Unfortunately, these tumors, like those produced by earlier genetically engineered mouse ccRCCs, are HIF2 independent.

Advances in targeting tumor microenvironment for immunotherapy

The tumor microenvironment (TME) provides essential conditions for the occurrence, invasion, and spread of cancer cells. Initial research has uncovered immunosuppressive properties of the TME, which include low oxygen levels (hypoxia), acidic conditions (low pH), increased interstitial pressure, heightened permeability of tumor vasculature, and an inflammatory microenvironment. The presence of various immunosuppressive components leads to immune evasion and affects immunotherapy efficacy. This indicates the potential value of targeting the TME in cancer immunotherapy. Therefore, TME remodeling has become an effective method for enhancing host immune responses against tumors. In this study, we elaborate on the characteristics and composition of the TME and how it weakens immune surveillance and summarize targeted therapeutic strategies for regulating the TME.

Spinal cord hemangioblastomas in von Hippel-Lindau disease

Background

von Hippel-Lindau disease (VHL) is an autosomal dominant familial neoplasia syndrome. The most common manifestation of VHL is central nervous system hemangioblastomas. VHL patients will often develop multiple hemangioblastomas along their craniospinal axis over their lifetime. Spinal cord hemangioblastomas account for nearly half of all nervous system hemangioblastomas in VHL.

Methods

The authors conducted a literature review and summation of available articles on spinal cord hemangioblastomas associated with VHL.

Results

The embryological origins, epidemiology, natural history, surgical outcomes, nonsurgical treatments, and future directions in spinal cord hemangioblastomas are discussed.

Conclusions

Hemangioblastomas in VHL are optimally managed with a multidisciplinary approach that includes surgical resection of symptomatic lesions. Novel treatments are gaining traction, but must be studied further for efficacy and safety.

Innovative solutions? Belzutifan therapy for hemangioblastomas in Von Hippel-Lindau disease: A systematic review and single-arm meta-analysis

BACKGROUND

Von Hippel-Lindau (VHL) disease is a rare autosomal dominant disorder that predisposes patients to develop multiple cysts and tumors, such as hemangioblastomas (HBs) and clear cell renal cell carcinoma (ccRCC), due to mutations in the VHL tumor suppressor gene. While treatment of HBs varies based on their characteristics and has improved patient survival, it still involves high morbidity and mortality, leading to ongoing debates and studies to refine therapy strategies. Recent developments include the emergence of Belzutifan, a novel inhibitor targeting hypoxia-inducible factor 2α (HIF-2α), which has shown promising results in ongoing trials, particularly for patients not immediately requiring surgery.

METHODS

This systematic review and meta-analysis aimed to comprehensively evaluate the efficacy and safety of Belzutifan for treating HBs associated with VHL disease. Search was conducted across Medline, Embase, Cochrane, and Web of Science databases. Statistical Analysis was performed, with proportions and 95 % confidence intervals. Statistical analyses were carried out using R Studio.

RESULTS

Ten studies were selected, comprising 553 patients. The population mean age was 40 (24-65), and 50 % of the population was formed by males. In terms of proportion, 6 analyses were performed: Disease Stability of 31 % [95 %CI:14 %-47 %; I2 = 2 %]; Disease Progression of 2 %[95 %CI:0 %-9 %; I2 = 0 %]; Partial Response of 75 % [95 %CI:54 %-96 %; I2 = 58 %]. Complete response of 1 % [95 %CI:0 %-7 %; I2 = 0 %];and Side effects, anemia 81 % rate [95 % CI:54 %-100 %; I2 = 94 %], and fatigue rate of 79 % [95 % CI:54 %-100 %;I2 = 94 %].

CONCLUSION

Results indicate that Belzutifan effectively stabilizes disease, reduces tumor progression, and achieves significant therapeutic responses, although side effects like anemia and fatigue were noted.

Metastatic pheochromocytoma and paraganglioma: Integrating tumor biology in clinical practice

Pheochromocytomas and paragangliomas (PPGL) are rare neuroendocrine tumors derived from chromaffin cells in the autonomic nervous system. Depending on their location, these tumors are capable of excessive catecholamine production, which may lead to uncontrolled hypertension and other life-threatening complications. They are associated with a significant risk of metastatic disease and are often caused by an inherited germline mutation. Although surgery can cure localized disease and lead to remission, treatments for metastatic PPGL (mPPGL)-including chemotherapy, radiopharmaceutical agents, multikinase inhibitors, and immunotherapy used alone or in combination- aim to control tumor growth and limit organ damage. Substantial advances have been made in understanding hereditary and somatic molecular signaling pathways that play a role in tumor growth and metastasis. Treatment options for metastatic disease are rapidly evolving, and this paper aims to provide a brief overview of the management of mPPGL with a focus on therapy options.

Endolymphatic Sac Tumors Associated With von Hippel-Lindau: A Case Report Highlighting Opportunity for Novel Orphan Drug Therapy

OBJECTIVE

To discuss the potential benefit of belzutifan therapy in a patient with von Hippel-Lindau (VHL) disease-associated endolymphatic sac tumor (ELST).

PATIENTS

Case report.

INTERVENTIONS

Clinical details of a patient with residual ELST after hearing preservation surgery who initiated belzutifan therapy postoperatively for concurrent renal cell carcinoma, as well as literature review of belzutifan and ELST.

MAIN OUTCOME MEASURES

The patient remained without radiologic evidence of growth of her residual tumor at 17 months post-initiation of belzutifan. It is unknown whether this represents therapeutic drug effect, nonviability of residual tumor, or slow tumor growth not captured radiographically within the duration of follow-up.

CONCLUSIONS

Belzutifan could have direct therapeutic benefit in patients with VHL-associated ELST.

Exposure-Response Analyses for Belzutifan to Inform Dosing Considerations and Labeling

Belzutifan (Welireg, Merck & Co., Inc., Rahway, NJ, USA) is an oral, potent hypoxia-inducible factor-2α inhibitor, recently approved in the United States for the treatment of von Hippel-Lindau (VHL) disease-associated renal cell carcinoma (RCC) and other VHL disease-associated neoplasms. Safety and efficacy were investigated in two clinical studies: a Phase 1 dose escalation/expansion study in solid tumors and RCC and a Phase 2 study in VHL-RCC. A population pharmacokinetic model was used to estimate belzutifan exposures to facilitate exposure-response (E-R) analyses for efficacy and safety endpoints. Relationships between exposure and efficacy (overall response rate, disease control rate, progression-free survival, best overall tumor size response, and other endpoints), safety outcomes (Grade ≥3 anemia, Grade ≥3 hypoxia, and time to first dose reduction/dose interruption), and pharmacodynamic biomarkers (erythropoietin [EPO] and hemoglobin [Hgb]) were evaluated using various regression techniques and time-to-event analyses. Efficacy E-R was generally flat with non-significant positive trends with exposure. The safety E-R analyses demonstrated a lack of relationship for Grade ≥3 hypoxia and a positive relationship for Grade ≥3 anemia, with incidences also significantly dependent on baseline Hgb. Exposure-dependent reductions in EPO and Hgb were observed. Based on the cumulative benefit-risk assessment in VHL disease-associated neoplasms using E-R, no a priori dose adjustment is recommended for any subpopulation. These analyses supported the benefit-risk profile of belzutifan 120 mg once daily dosing in patients with VHL-RCC for labeling and the overall development program.

Total loss of VHL gene function impairs neuroendocrine cancer cell fitness due to excessive HIF2α activity

Loss-of-function germline von Hippel-Lindau (VHL) tumor suppressor mutations cause VHL disease, which predisposes individuals to kidney cancer, hemangioblastomas, and paragangliomas. The risk that a given VHL disease family will manifest some or all these tumor types is profoundly influenced by the VHL allele it carries. For example, almost all VHL disease families that develop paraganglioma have missense VHL mutations. VHL families with null VHL alleles develop kidney cancer and hemangioblastomas without a high risk of paraganglioma. The latter is surprising because the VHL gene product, pVHL, suppresses the HIF2 transcription factor and gain-of-function HIF2 mutations are also linked to paraganglioma. Paragangliomas arise from the sympathetic or parasympathetic nervous system. Given the lack of human paraganglioma cell lines, we studied the effects of inactivating VHL in neuroblastoma cell lines, which also arise from the sympathetic nervous system. We found that total loss of pVHL function profoundly impairs the fitness of neuroblastoma cell lines in a HIF2-dependent manner both ex vivo and in vivo. This fitness defect can be rescued by pVHL variants linked to paraganglioma, but not by pVHL variants associated with a low risk of paraganglioma. These findings suggest that HIF2 activity above a critical threshold prevents the development of paraganglioma.

Belzutifan for patients with von Hippel-Lindau disease-associated CNS haemangioblastomas (LITESPARK-004): a multicentre, single-arm, phase 2 study

BACKGROUND

The first-in-class hypoxia-inducible factor-2α inhibitor, belzutifan, showed clinically meaningful antitumour activity in von Hippel-Lindau (VHL) disease-associated neoplasms in the ongoing, single-arm, phase 2 LITESPARK-004 study. We aimed to investigate antitumour activity with an additional 16 months of follow-up and present updated results for the subgroup of patients with CNS haemangioblastomas.

METHODS

In the multicentre, single-arm, phase 2 LITESPARK-004 study, adults (aged ≥18 years) from 11 cancer centres or hospitals in the USA, Denmark, France, and the UK, with germline VHL alterations, at least one measurable renal cell carcinoma tumour, no renal cell carcinoma tumour greater than 3 cm requiring immediate surgical intervention, an Eastern Cooperative Oncology Group performance status 0 or 1, and no previous systemic therapy received oral belzutifan 120 mg once daily until unacceptable toxicity, disease progression, or patient decision to withdraw. The primary endpoint, evaluated in patients with CNS haemangioblastomas, was the proportion of patients with an objective response per RECIST version 1.1 by an independent review committee. We assessed response using two approaches. In approach 1, we evaluated all measurable (≥1 cm maximum diameter) or non-measurable lesions at baseline, including both the solid lesion and the associated cystic component if present. In approach 2, we evaluated only baseline lesions with a measurable (≥1 cm maximum diameter) solid lesion. Antitumour activity was assessed in all patients who received at least one dose of belzutifan. This study is no longer recruiting but is ongoing, and is registered with Clinicaltrials.gov, NCT03401788.

FINDINGS

Between May 31, 2018, and March 29, 2019, of 67 patients screened, 61 (32 [52%] male and 29 [48%] female) were enrolled; 50 (82%) had at least one CNS haemangioblastoma evaluable at baseline (184 total lesions). Median follow-up for the 50 patients with CNS haemangioblastomas was 38·0 months (IQR 36·7-40·1). In approach 1, 22 of 50 patients (44% [95% CI 30-59]) had an objective response. In approach 2, 19 of 25 patients (76% [55-91] had an objective response. 23 (46%) of 50 patients had a grade 3-5 all-cause adverse event. 19 (38%) patients reported grade 3 adverse events, the most common of which was anaemia (in 6 [12%] patients). Two of 50 patients (4%) reported grade 4 events (retinal vein occlusion and embolism). Two patients died owing to adverse events not considered treatment-related (suicide and toxicity to various agents).

INTERPRETATION

Belzutifan showed meaningful antitumour activity in VHL disease-associated CNS haemangioblastomas that was sustained for more than 3 years of treatment. These results continue to support belzutifan as a systemic treatment option for patients with VHL disease-related CNS haemangioblastomas.

FUNDING

Merck Sharp & Dohme, National Institutes of Health, and National Cancer Institute.

Neurosurgical Implications of Targeting Hypoxia-Inducible Factor 2α in Hemangioblastomas with Belzutifan

OBJECTIVE

To highlight the neurosurgical implications of the hypoxia-inducible factor-2α- targeting agent belzutifan in the management of both von-Hippel Lindau (VHL)-associated and sporadic hemangioblastomas (HBLs).

METHODS

The literature was queried for VHL, HBLs, and belzutifan. A summary of recent uses of belzutifan and currently ongoing clinical trials that are investigating the use of belzutifan in the treatment of HBLs is presented.

RESULTS

VHL disease occurs as a result of germline mutations in the VHL tumor suppressor gene on chromosome 3p25-p26, leading to growth of benign and malignant tumors such as HBLs. The possibility of intermittent growth in HBLs indicates that it is important to avoid hasty surgical interventions. Belzutifan is the first nonsurgical food and drug administration-approved treatment for VHL disease-related tumors that may delay or circumvent the need for surgery or radiation therapy by inhibiting HIF-2α, an important component of cellular hypoxic response. There is limited real-world experience of belzutifan in patients with HBLs as a primary indication, though there are 2 phase II clinical trials investigating the use of belzutifan in the treatment of HBLs.

CONCLUSIONS

There is limited experience regarding the use of belzutifan for CNS hemangioblastoma. While its application has been limited to a small group of clinical cases, it has exhibited significant efficacy in reducing the size and consequences of HBLs. Based on the promising outcomes observed in individual patient experiences and ongoing clinical trials, we infer that further exploration and integration of belzutifan into neurosurgical treatment plans for both sporadic and VHL-associated HBLs are warranted.

Renal Cell Carcinoma: A Review

Importance

Renal cell carcinoma (RCC) is a common malignancy, with an estimated 434 840 incident cases worldwide in 2022. In the US, it is the sixth most common cancer among males and ninth among females.

Observations

Clear cell RCC is the most common histologic subtype (75%-80% of cases) and is characterized by inactivation of the von Hippel Lindau (VHL) tumor suppressor gene. Many patients (37%-61%) are diagnosed with RCC incidentally on an abdominal imaging study such as ultrasound or computed tomographic scan, and 70% of patients have stage I RCC at diagnosis. Although its incidence has increased approximately 1% per year from 2015 through 2019, the mortality rate of RCC has declined about 2% per year in the US from 2016 through 2020. Patients with a solid renal mass or complex cystic renal mass should be referred to urology. Treatment options for RCC confined to the kidney include surgical resection with partial or radical nephrectomy, ablative techniques (eg, cryoablation, radiofrequency ablation, radiation), or active surveillance for some patients (especially those with renal masses <2 cm). For patients with renal masses less than 4 cm in size (48% of patients), partial nephrectomy can result in a 5-year cancer-specific survival of more than 94%. For advanced or metastatic RCC, combinations of immune checkpoint inhibitors or the combination of immune checkpoint inhibitors with tyrosine kinase inhibitors are associated with tumor response of 42% to 71%, with a median overall survival of 46 to 56 months.

Conclusions and Relevance

RCC is a common malignancy that is often diagnosed incidentally on an abdominal imaging study. Seventy percent of patients are diagnosed with stage I RCC and 11% of patients with stage IV. First-line treatments for early-stage RCC are partial or radical nephrectomy, which can result in 5-year cancer-specific survival of more than 94%, ablative techniques, or active surveillance. New treatment options for patients with metastatic RCC include immune checkpoint inhibitors and tyrosine kinase inhibitors.

Exploring Tumor Heterogeneity: Radiogenomic Assessment of ADFP in Low WHO/ISUP Grade Clear Cell Renal Cell Carcinoma

This study aimed to investigate the association between metabolic lipid computed tomography (CT) features and adipose differentiation-related protein (ADFP) expression in clear cell renal cell carcinoma (ccRCC), providing insights into non-invasive methods for assessing ADFP expression and tumor characteristics. This study utilized data from The Cancer Genome Atlas and the Cancer Imaging Archive to analyze genetic alterations and imaging characteristics in ccRCC patients. Tumoral Hounsfield units (HU) analysis and quantification of abdominal adipose tissue compartments were performed using CT images. Statistical analyses were conducted to compare tumoral HU values according to ADFP gene expression and World Health Organization/International Society of Urological Pathology (WHO/ISUP) tumor grade, as well as to explore correlations between tumoral HU values and adipose tissue quantification. Among the 174 identified patients, those with ADFP gene expression showed significantly lower minimum tumoral HU values in low-grade cancers compared to high-grade cancers. Similarly, patients with low-grade cancers expressing ADFP exhibited lower minimum tumoral HU values compared to those without ADFP expression. Negative correlations were observed between minimum tumoral HU values and visceral adipose tissue, subcutaneous adipose tissue, and total adipose tissue in both ccRCC patients with and without ADFP expression. This study reveals a significant association between metabolic lipid CT features and ADFP expression in ccRCC patients. Lower minimum tumoral HU values, suggestive of higher intracellular lipid accumulation, were observed in tumors with low WHO/ISUP grade and ADFP expression.

Molecular Dynamics Reveals Altered Interactions between Belzutifan and HIF-2 with Natural Variant G323E or Proximal Phosphorylation at T324

In patients with von-Hippel Lindau (VHL) disease, hypoxia-independent accumulation of HIF-2α leads to increased transcriptional activity of HIF-2α:ARNT that drives cancers such as renal cell carcinoma. Belzutifan, a recently FDA-approved drug, is designed to prevent the transcriptional activity of HIF-2α:ARNT, thereby overcoming the consequences of its unnatural accumulation in VHL-dependent cancers. Emerging evidence suggests that the naturally occurring variant G323E located in the HIF-2α drug binding pocket prevents inhibitory activity of belzutifan analogs, though the mechanism of inhibition remains unclear. Interestingly, proximal phosphorylation at neighboring T324, previously shown to regulate HIF-2 protein interactions, has also been proposed to affect HIF-2 drug binding. Here, we used molecular dynamics (MD) simulations to understand and compare the molecular-level effects of G323E and phospho-T324 (pT324) on the belzutifan bound-HIF-2α:ARNT complex. We find that both G323E and pT324 increase structural flexibility within the drug binding site and reduce the apparent binding affinity for belzutifan. Whereas the effects of G323E are concentrated in the binding pocket Fα helix within the HIF-2α PAS-B domain, pT324 decreased the belzutifan binding affinity and stabilized the HIF-2 heterodimer through an alternate mechanism involving polar interactions between the HIF-2α PAS-B and PAS-A domains. Further analysis via ensemble machine learning uncovered important and distinct interchain residue interactions modified by G323E and pT324. These findings reveal a molecular mechanism of G323E-induced drug resistance and suggest that pT324 may also affect the efficacy of HIF-2 drug binding interactions via allosteric effects.

Cumulative Impact of Serial Partial Nephrectomy for the Treatment of Recurrent Renal Masses

PURPOSE

Reoperative partial nephrectomy (RePN) offers several advantages for the treatment of recurrent, multifocal renal masses. RePN has been previously demonstrated to be technically feasible and delay the need for renal replacement therapy. However, there is still inherent complexity and known risks to reoperative nephrectomy. We studied the largest population of RePNs to characterize renal functional outcomes and the likelihood of intra- and postoperative complications.

MATERIALS AND METHODS

Query of an institutional surgical registry was conducted. Demographic data, serum creatinine for estimated glomerular filtration rate (eGFR), and protein dipstick results were assessed within 1 week prior to surgery, and postoperative function assessments were studied within a year of surgery. RePN was defined as serial surgical resection of the ipsilateral renal unit.

RESULTS

A total of 1131 partial nephrectomies performed on 663 patients at a single center were retrospectively evaluated. In reoperative cases, median number of operations per renal unit was 2 (range: 2-6). There was a stepwise decline in eGFR with an average decline of 6.1 with each RePN. With each subsequent nephrectomy, surgical duration, estimated blood loss, and incidence of preoperative anemia increased. Postoperative eGFR showed a significant positive association with preoperative eGFR, while negative associations were found with age, number of previous ipsilateral partial nephrectomies, number of tumors, and largest tumor size. High-grade complications were associated with the number of ipsilateral partial nephrectomies, tumor count, and tumor size. Robotic or laparoscopic procedures exhibited a likelihood of grade 3 or greater complications compared to open surgery.

CONCLUSIONS

RePN contributes to renal dysfunction and an increased risk of surgical complications. Intraoperative blood loss and surgical duration increase with subsequent nephrectomy. Such risks are dependent on the number of prior operative interventions on the kidney, suggesting a stepwise progression of surgical morbidity.

Molecular Genetics of Pheochromocytoma/Paraganglioma

Pheochromocytomas and paragangliomas (PPGL) are neuroendocrine tumors which secrete catecholamines, causing cardiovascular compromise. While isolated tumors and locoregional disease can be treated surgically, treatment options for metastatic disease are limited, and no targeted therapies exist. Approximately 25% of PPGL are causatively associated with germline pathogenic variants, which are known risk factors for multifocal and metastatic PPGL. Knowledge of somatic driver mutations continues to evolve. Molecular classification of PPGL has identified three genomic subtypes: Cluster 1 (pseudohypoxia), Cluster 2 (kinase signaling) and Cluster 3 (Wnt-altered). This review summaries recent studies characterizing the tumor microenvironment, genomic drivers of tumorigenesis and progression, and current research on molecular targets for novel diagnostic and therapeutic strategies in PPGL.