The outcome of central nervous system hemangioblastomas in Von Hippel-Lindau (VHL) disease treated with belzutifan: a single-institution retrospective experience.

PURPOSE: Belzutifan is a Hypoxia Inducible Factor 2-alpha inhibitor approved in 2021 by the FDA for the treatment of renal cell carcinoma (RCC) in patients with Von-Hippel Landau (VHL) disease. These patients can also present with central nervous system (CNS) hemangioblastomas (HBs). We aim to study the effectiveness and adverse effects of belzutifan for CNS HBs, by reporting our preliminary institutional experience. METHODS: We present a series of VHL patients with CNS HBs undergoing treatment with belzutifan for RCC. All the included patients met the RECIST inclusion criteria. The clinical and radiological outcome measures included: Objective response rate (ORR), time-to-response (TTR), adverse events (AE), and patient response. Patient response was classified as partial response (PR), complete response (CR), progressive disease (PD), or stable disease (SD). RESULTS: Seven patients with 25 HBs were included in our study. A belzutifan dose of 120 mg/day PO was administered for a median of 13 months (range 10-17). Median follow up time was 15 months (range 10-24). An ORR of 71% was observed. The median TTR was 5 months (range: 1-10). None of the patients showed CR, while 5 patients (71.4%) showed PR and 2 (28.5%) showed SD. Among patients with SD the maximum tumor response was 20% [increase/decrease] of the lesion diameter. All the patients experienced decreased hemoglobin concentration, fatigue, and dizziness. None of the patients experienced severe anemia (grade 3-4 CTCAE). CONCLUSION: Belzutifan appears to be an effective and safe treatment for CNS hemangioblastoma in VHL patients. Further clinical trials to assess the long-term effectiveness of the medication are required.

Belzutifan in adults with VHL-associated central nervous system hemangioblastoma: a single-center experience.

PURPOSE: Belzutifan is a selective inhibitor of hypoxia-inducible factor 2 alpha (HIF-2a) that has emerged as a targeted therapy option for Von Hippel-Lindau (VHL) syndrome-associated tumors with recent FDA approval. There is limited real-world evidence regarding safety and efficacy in CNS hemangioblastoma. Our objective was to report on our clinical experience with belzutifan in adult patients with VHL-associated CNS hemangioblastoma. METHODS: We retrospectively reviewed our institutional experience of belzutifan in adult patients (> 18 years of age at time of therapy) with VHL and craniospinal CNS hemangioblastomas not amenable to surgical resection. The period for study review was October 2021 to March 2023. RESULTS: 4 patients (all female) with a median age of 36 years at time of belzutifan initiation were included. Median duration of therapy at last follow-up was 11 months (6-17 months). All patients had radiographic response to therapy after a median of 3 months (2-5 months), with maximal response to therapy after a median of 8 months (3-17 months). Therapy was well tolerated, with the most common adverse effect being anemia. No patients had treatment pauses or dose adjustments due to belzutifan-related toxicity. No patients experienced hypoxia. CONCLUSION: We showed that belzutifan is safe and well-tolerated with strong disease response for CNS hemangioblastoma in adults with VHL, supporting continued use of belzutifan in this patient population. Future studies should assess duration of treatment, effects of cessation after long-term use, and markers of therapeutic response.

Selective HIF2A Inhibitors in the Management of Clear Cell Renal Cancer and Von Hippel-Lindau-Disease-Associated Tumors.

Von Hippel-Lindau (VHL) loss is the hallmark event characterizing the clear cell renal cancer subtype (ccRCC). Carriers of germinal VHL mutations have an increased prevalence of kidney cysts and ccRCC as well as hemangioblastoma, pheochromocytoma and pancreatic neuroendocrine tumors. In both sporadic and inherited ccRCC, the primary mechanism of VHL-mediated carcinogenesis is the abnormal stabilization of hypoxia-inducible factors (HIF1A and HIF2A). While HIF1A acts as a tumor suppressor and is frequently lost through inactivating mutations/14q chromosome deletions, HIF2A acts as an oncogene promoting the expression of its target genes (VEGF, PDGF, CAIX Oct4, among others). Selective HIF2a inhibitors block the heterodimerization between HIF2A and ARNT, stopping HIF2A-induced transcription. Several HIF2A inhibitors have entered clinical trials, where they have shown a favorable toxicity profile, characterized by anemia, fatigue and edema and promising activity in heavily pretreated ccRCC patients. Belzutifan, a second-generation HIF2a inhibitor, was the first to receive FDA approval for the treatment of unresectable ccRCC in VHL syndrome. In this review, we recapitulate the rationale for HIF2a blockade in ccRCC, summarize the development of HIF2a inhibitors from preclinical models up to its introduction to the clinic with emphasis on Belzutifan, and discuss their role in VHL disease management.

Development of drugs targeting hypoxia-inducible factor against tumor cells with VHL mutation: Story of 127 years.

Intratumoral hypoxia is associated with tumor progression and therapeutic resistance. The VHL tumor suppressor gene was identified in 1993, and later studies revealed that the gene product pVHL interacts with other proteins to form the VBC complex. The VBC complex functions as an E3 ubiquitin ligase and regulates the abundance of the α-subunit of the transcription factor hypoxia-inducible factor (HIF). Hypoxia-inducible factor regulates thousands of genes required for cells to adapt and survive in hypoxic conditions, and thus pVHL plays a major role in oxygen-sensing pathways. Patients with von Hippel-Lindau (VHL) disease, harboring a germline mutation of the VHL gene, develop renal cell carcinomas and a series of tumors showing hypervascular phenotypes. The extensive findings that have clarified the function of VHL have contributed to the development of novel first-in-human drugs, including belzutifan, a HIF-2α inhibitor. The 2019 Nobel Prize in Physiology or Medicine was awarded to Dr. William G. Kaelin Jr., Dr. Peter J. Ratcliffe, and Dr. Gregg L. Semenza as researchers contributing to clarifying the mechanism of the oxygen-sensing pathway of cells. The first report of VHL disease was in 1894, meaning the development of a specific drug for this disease took almost 125 years. In this article, we describe how researchers and clinician scientists successfully clarified the function of VHL and achieved a preclinical proof of concept to apply for clinical trials, key requirements for drug development.

FDA Approval Summary: Belzutifan for von Hippel-Lindau Disease-Associated Tumors.

On August 13, 2021, the FDA approved belzutifan (WELIREG, Merck), a first-in-class hypoxia-inducible factor (HIF) inhibitor for adult patients with von Hippel-Lindau (VHL) disease who require therapy for associated renal cell carcinoma (RCC), central nervous system (CNS) hemangioblastomas, or pancreatic neuroendocrine tumors (pNET), not requiring immediate surgery. The FDA granted approval based on the clinically meaningful effects on overall response rate (ORR) observed in patients enrolled in Study MK-6482-004. All 61 patients had VHL-associated RCC; some also had CNS hemangioblastomas and/or pNET. For VHL disease-associated RCC, ORR was 49% [95% confidence interval (CI), 36-62], median duration of response (DoR) was not reached, 56% of responders had DoR ≥12 months, and median time to response was 8 months. Twenty-four patients had measurable CNS hemangioblastomas with an ORR of 63% (95% CI, 41-81), and 12 patients had measurable pNET with an ORR of 83% (95% CI, 52-98). For these tumors, median DoR was not reached, with 73% and 50% of patients having response durations ≥12 months for CNS hemangioblastomas and pNET, respectively. The most common adverse reactions, including laboratory abnormalities, reported in ≥20% were anemia, fatigue, increased creatinine, headache, dizziness, increased glucose, and nausea. Belzutifan can render some hormonal contraceptives ineffective and can cause embryo-fetal harm during pregnancy. This article summarizes the data and the FDA thought process supporting traditional approval of belzutifan for this indication.

Belzutifan: A Narrative Drug Review.

Von Hippel-Lindau disease is an autosomal dominant disorder characterised by renal cell carcinomas, pancreatic neuroendocrine tumours, central nervous system hemangioblastomas, retinoblastomas, and tumours of the reproductive tract. This disease results from loss of function mutations in the tumour suppressor gene known as the Von Hippel-Lindau gene, located on chromosome 3. Loss of function mutation in the Von Hippel-Lindau gene results in the accumulation of a protein known as a hypoxia-inducible factor, which promotes cellular proliferation and angiogenesis, leading to cancer. Belzutifan inhibits the hypoxia-inducible factor by binding to the Per-ARNT -Sim-B binding pocket on the hypoxia-inducible factor -2α, inhibiting cellular proliferation and angiogenesis. In our thorough literature review, we identified 37 relevant articles. Belzutifan showed clinically meaningful response rates for both Von Hippel-Lindau disease-associated renal cell carcinomas and non-renal cell cancers. The pharmacokinetic profile of belzutifan was much better than its congener molecules due to the optimisation of its dihalide groups from germinal to vicinal. The pharmacodynamic effect of belzutifan was confirmed by its ability to decrease serum erythropoietin, which is a direct result of hypoxia-inducible factor- 2α inhibition. The significant side effects observed were anaemia, hypoxia, fatigue, hypertension, visual impairment and weight gain. Multiple clinical trials are currently underway to determine the role of beluztifan as part of combination regimens in treating Von Hippel-Lindau diseaseassociated malignancies.

Blockade of ß2-Adrenergic Receptor Reduces Inflammation and Oxidative Stress in Clear Cell Renal Cell Carcinoma.

Von Hippel-Lindau (VHL) syndrome is a rare inherited cancer disease where the lack of VHL protein triggers the development of multisystemic tumors such us retinal hemangioblastomas (HBs), CNS-HBs, and clear cell renal cell carcinoma (ccRCC). Since standard therapies in VHL have shown limited response, leaving surgery as the only possible treatment, targeting of the ß2-adrenergic receptor (ADRB2) has shown therapeutic antitumor benefits on VHL-retinal HBs (clinical trial), VHL-CNS HBs, and VHL-ccRCC (in vitro and in vivo). In the present study, we wanted to look deep into the effects of the ADRB2 blockers propranolol and ICI-118,551 on two main aspects of cancer progression: (i) the changes on the inflammatory response of ccRCC cells; and (ii) the modulation on the Warburg effect (glycolytic metabolism), concretely, on the expression of genes involved in the cell reactive oxygen species (ROS) balance and levels. Accordingly, in vitro studies with primary VHL-ccRCC and 786-O cells measuring ROS levels, ROS-expression of detoxifying enzymes, and the expression of p65/NF-κB targets by RT-PCR were carried out. Furthermore, histological analyses of ccRCC samples from heterotopic mouse xenografts were performed. The obtained results show that ADRB2 blockade in ccRCC cells reduces the level of oxidative stress and stabilizes the inflammatory response. Thus, these data further support the idea of targeting ADRB2 as a promising strategy for the treatment of VHL and other non-VHL tumors.

Intravitreous treatment of severe ocular von Hippel-Lindau disease using a combination of the VEGF inhibitor, ranibizumab and PDGF inhibitor, E10030: Results from a phase 1/2 clinical trial.

BACKGROUND: Treatment options for severe ocular von Hippel-Lindau (VHL) disease are limited. This trial evaluated preliminary safety and potential efficacy of combination intravitreous injection with ranibizumab, a vascular endothelial growth factor (VEGF) inhibitor, and E10030, a PDGF inhibitor, for eyes with VHL disease-associated retinal hemangioblastoma (RH) not amenable or responsive to thermal laser photocoagulation. METHODS: This was a prospective, single-arm, open-label phase 1/2 study, comprised of three adults with VHL-associated RH and vision loss. Intravitreous injections of ranibizumab (0.5 mg) and E10030 (1.5 mg) were given unilaterally every 4 weeks in the study eye through 16 weeks, then every 8 weeks through 48 weeks. Supplementary standard care therapies were allowed without restriction after 40 weeks. The primary outcome was the ocular and systemic adverse effect profile at 52 weeks. Secondary outcomes included changes in best-corrected visual acuity (BCVA), RH size, exudation, epiretinal proliferation and retinal traction, and need for ablative treatment of RH or ocular surgery at week 52. RESULTS: Three participants each received nine injections prior to week 52 and were followed for 104 weeks. One participant manifested mild episodic ocular hypertension in the study eye. Change in BCVA in the study eye at week 52 for the three participants was -5, -12 and +2 letters. No reduction in RH size was measured at 52 weeks. Variable mild improvements in exudation in two participants at week 16 were not sustained through week 52. CONCLUSIONS: Combination intravitreous injection with ranibizumab and E10030 demonstrated a reasonable preliminary safety profile, but limited treatment effect.

Therapeutically actionable signaling node to rescue AURKA driven loss of primary cilia in VHL-deficient cells.

Loss of primary cilia in cells deficient for the tumor suppressor von Hippel Lindau (VHL) arise from elevated Aurora Kinase A (AURKA) levels. VHL in its role as an E3 ubiquitin ligase targets AURKA for degradation and in the absence of VHL, high levels of AURKA result in destabilization of the primary cilium. We identified NVP-BEZ235, a dual PI3K/AKT and mTOR inhibitor, in an image-based high throughput screen, as a small molecule that restored primary cilia in VHL-deficient cells. We identified the ability of AKT to modulate AURKA expression at the transcript and protein level. Independent modulation of AKT and mTOR signaling decreased AURKA expression in cells confirming AURKA as a new signaling node downstream of the PI3K cascade. Corroborating these data, a genetic knockdown of AKT in cells deficient for VHL rescued the ability of these cells to ciliate. Finally, inhibition of AKT/mTOR using NVP-BEZ235 was efficacious in reducing tumor burden in a 786-0 xenograft model of renal cell carcinoma. These data highlight a previously unappreciated signaling node downstream of the AKT/mTOR pathway via AURKA that can be targeted in VHL-null cells to restore ciliogenesis.

MK-6482 as a potential treatment for von Hippel-Lindau disease-associated clear cell renal cell carcinoma.

INTRODUCTION: Von Hippel-Lindau (VHL) disease is an inherited autosomal dominant syndrome caused by a germline mutation and/or deletion of the VHL gene. Inappropriate hypoxia-inducible factor (HIF)-mediated transcription of proangiogenic and metabolic genes leads to the development of tumors and cysts in multiple organs. Surgery is a standard treatment for localized tumors with a risk of metastasis or organ dysfunction. Repeated surgeries cause substantial morbidity and have a major impact on quality of life. There is an urgent need to develop effective and safe systemic treatments for VHL disease manifestations. The small-molecule HIF 2 alpha inhibitor MK-6482 (belzutifan) has demonstrated significant efficacy in VHL disease related renal cell carcinomas, hemangioblastomas, and pancreatic neuroendocrine tumors while demonstrating an acceptable safety profile. AREAS COVERED: This paper reviews the development of the HIF-2 alpha inhibitor, MK-6482, and discusses preliminary results of ongoing phase I/II studies in renal cell carcinoma (RCC) and VHL disease. An examination of ongoing clinical development of MK-6482 and perspectives on potential future developments and challenges are offered. EXPERT OPINION: Because of its favorable safety profile, its clear efficacy in VHL disease, promising findings in sporadic, advanced RCC, and convenient oral formulation, MK-6482 is expected to become a leading treatment for VHL disease. Among other currently available oral agents, we believe that MK-6482 will be a preferred treatment for VHL-associated RCC.

Intravitreal Triamcinolone Acetonide in Von Hippel-Lindau Patient with Novel Mutation.

von Hippel-Lindau (VHL) is a multisystemic inherited disease which most commonly affects the retina and central nervous system. The hallmark retinal manifestation of VHL in the eye is retinal capillary hemangioblastoma (RCH). Significant visual morbidity can result from exudative retinal detachments (ERDs) or tractional retinal detachments. Here, we present a 21-year-old male with long-standing poor vision in the right eye. On examination, he was found to have a massive ERD in the right eye with multiple RCH in both eyes. Genetic testing revealed a heterozygous (c.390dupT) mutation in the VHL gene. Intravitreal triamcinolone acetonide injection resulted in subretinal fluid absorption and near total resolution of ERD. Retinal flattening made RCH accessible for laser photocoagulation. Following multiple focal lasers to the RCH, the lesions were regressed with the flat retina and stable vision.

Continuous angiogenesis inhibition in the treatment for von Hippel-Lindau-related hemangioblastomas of retina and spinal cord.

Hemangioblastomas of central nervous system are rare and indolent. Twenty-five percent of cases are in association with von Hippel-Lindau disease. Surgery is the standard therapy but un-resectable or recurrent cases need radiation or systemic therapy. Defective von Hippel-Lindau tumor suppressor gene leads to vascular endothelial growth factor overexpression and enhance angiogenesis. Here we report a 19-year-old male, diagnosed at pediatric age, who had retinal and spinal cord hemangioblastomas. He was treated 34 months with bevacizumab, afterwards 12 months with thalidomide and tertiary therapy with pazopanib for 9 months which still goes on. In case of need, radiation and surgical procedures were performed. Vascular endothelial growth factor inhibition continuity is a good therapeutic option, which improves outcomes of von Hippel-Lindau-related hemangioblastomas.

STF-62247 accumulates in lysosomes and blocks late stages of autophagy to selectively target von Hippel-Lindau-inactivated cells.

Autophagy is a highly conserved, homeostatic process by which cytosolic components reach lysosomes for degradation. The roles played by different autophagic processes in cancer are complex and remain cancer type and stage dependent. Renal cell carcinoma (RCC) is the most common subtype of kidney cancer and is characterized by the inactivation of the von Hippel-Lindau (VHL) tumor suppressor. Our previous study identified a small compound, STF-62247, as an autophagy-modulating molecule causing selective cytotoxicity for VHL-inactivated cells. This present study investigates the effects of STF-62247 specifically on the macroautophagic flux to better characterize its mechanism of action in RCC. Our results clearly demonstrate that this compound is a potent blocker of late stages of autophagy. We show that inhibiting autophagy by CRISPR knockouts of autophagy-related genes rendered VHL-deficient cells insensitive to STF-62247, uncovering the importance of the autophagic pathway in STF-selective cell death. By exploiting the autofluorescence of STF-62247, we pinpointed its cellular localization to lysosomes. Finally, in response to prolonged STF treatments, we show that VHL-proficient cells are able to surmount the block in late stages of autophagy by restoring their lysosome numbers. Conversely, an increase in autophagic vesicles accompanied by a time-dependent decrease in lysosomes was observed in VHL-deficient cells. This is the first mechanistic study investigating STF-62447's effects on the autophagic flux in RCC. Importantly, our study reclassifies STF-62247 as a blocker of later stages of autophagy and highlights the possibility of blocking this process through lysosome disruption in VHL-mutated RCCs.

Effect of clarithromycin in von Hippel-Lindau syndrome: a case report.

Von Hippel-Lindau (VHL) syndrome is caused by germline mutations in the VHL gene and is accompanied by the development of both benign and malignant tumors. Clarithromycin (CAM) is a widely used anti-inflammatory drug that has also been proven effective for treating some cancers. In this study, we present a novel case of a 38-year-old female patient with VHL syndrome confirmed by computed tomography, with no relevant family history. The patient was only offered close follow-up observation after diagnosis, but was orally administered CAM twice daily when her disease progressed. After treatment for 3 months, her inner ear tumors had stopped growing and her kidney cysts had shrunk. Her pancreatic tumors treated with CAM showed no significant increase in size, and the lymph node swelling disappeared. CAM treatment was interrupted for 2 years and then stopped for 5 years when improvements were noted; the patient's condition thereafter gradually improved and finally stabilized with no obvious side effects. We discuss this case in the context of the published literature and consider the possible mechanisms of CAM action in the treatment of VHL syndrome. To our knowledge, this is the first case report of a patient with VHL syndrome treated with CAM.

Pazopanib in patients with von Hippel-Lindau disease: a single-arm, single-centre, phase 2 trial.

BACKGROUND: No approved systemic therapy exists for von Hippel-Lindau disease, an autosomal dominant disorder with pleiotropic organ manifestations that include clear cell renal cell carcinomas; retinal, cerebellar, and spinal haemangioblastomas; pheochromocytomas; pancreatic serous cystadenomas; and pancreatic neuroendocrine tumours. We aimed to assess the activity and safety of pazopanib in patients with von Hippel-Lindau disease. METHODS: In this non-randomised, single-centre, open-label, phase 2 trial, adult patients with clinical manifestations of von Hippel-Lindau disease were recruited from the University of Texas MD Anderson Cancer Center (Houston, TX, USA) and were treated with pazopanib (800 mg orally daily) for 24 weeks, with an option to continue treatment if desired by the patient and treating physician. Primary endpoints were the proportion of patients who achieved an objective response and safety in the per-protocol population. The objective response was measured for each patient and each lesion type. Radiographic assessments were done at baseline and every 12 weeks throughout the study. Activity and safety were assessed with continuous monitoring and a Bayesian design. This study is registered with ClinicalTrials.gov, number NCT01436227, and is closed to accrual. FINDINGS: Between Jan 18, 2012, and Aug 10, 2016, we screened 37 patients with genetically confirmed or clinical features consistent with von Hippel-Lindau disease, of whom 31 eligible patients were treated with pazopanib. The proportion of patients who achieved an objective response was 42% (13 of 31 patients). By lesion sites responses were observed in 31 (52%) of 59 renal cell carcinomas, nine (53%) of 17 pancreatic lesions, and two (4%) of 49 CNS haemangioblastomas. Seven (23%) of 31 patients chose to stay on the treatment after 24 weeks. Four (13%) of 31 patients withdrew from the study because of grade 3 or 4 transaminitis, and three (10%) discontinued study treatment because of treatment intolerance with multiple intercurrent grade 1-2 toxicities. Treatment-related serious adverse events included one case each of appendicitis and gastritis and one patient had a fatal CNS bleed. INTERPRETATION: Pazopanib was associated with encouraging preliminary activity in von Hippel-Lindau disease, with a side-effect profile consistent with that seen in previous trials. Pazopanib could be considered as a treatment choice for patients with von Hippel-Lindau disease and growing lesions, or to reduce the size of unresectable lesions in these patients. The safety and activity of pazopanib in this setting warrants further investigation. FUNDING: Novartis Inc and NIH National Cancer Institute core grant.

A retrospective case study of sunitinib treatment in three patients with Von Hippel-Lindau disease.

Von Hippel-Landau (VHL) disease is characterized by malignant and benign tumors in multiple organs. Sunitinib, a tyrosine kinase inhibitor, has been clinically available for treating sporadic patients with recurrent or unresectable and metastatic clear renal cell carcinomas (cRCCs) and metastatic lesions of the lung, but its effect on VHL disease-associated tumors remains poorly understood. This retrospective case series examined the effect of sunitinib on RCC, hemangioblastomas, pheochromocytomas, and pancreatic neuroendocrine tumors in patients with confirmed VHL. Of note, three patients with VHL disease who were treated with sunitinib were identified from a review of their medical records. The efficacy of sunitinib was evaluated by comparing computed tomography (CT) or magnetic resonance imaging (MRI) scans conducted before and after treatment. Adverse side effects associated with sunitinib were assessed and recorded. All three patients with VHL disease exhibited clinical improvement after treatment with sunitinib. Patient 1 exhibited a decrease in the size of both their pheochromocytoma and RCC after 19 months of sunitinib treatment. RCCs in Patients 2 and 3 exhibited stable response to sunitinib for approximately 1 and 6 years, respectively. All the patients reported tolerable side effects. Therefore sunitinib treatment was associated with either partial response or stable control of VHL-related RCCs, pheochromocytomas and pancreatic neuroendocrine tumor (NET) with acceptable side effects. Further evaluation of sunitinib in patients with VHL disease in larger prospective studies is warranted.