Pilot study of dovitinib in patients with von Hippel-Lindau disease

Belzutifan: a novel therapeutic for the management of von Hippel-Lindau disease and beyond

The identification of the VHL gene and its role in regulating the hypoxia-inducible factor signaling pathway has helped to revolutionize the treatment of renal cell carcinoma (RCC). Belzutifan is a novel small-molecule inhibitor of hypoxia-inducible factor 2α which has demonstrated efficacy in treating von Hippel-Lindau (VHL) disease, earning regulatory approvals for this indication. There is also early evidence for efficacy in sporadic RCC. Belzutifan has a favorable safety profile. Several clinical trials are currently ongoing, which should help in identifying this promising drug's role in RCC and beyond. This review summarizes the history, pharmacology and clinical evidence for belzutifan use to date, and also explores unanswered questions as they relate to this novel therapeutic agent.

von Hippel-Lindau disease-related neoplasia with an emphasis on renal manifestations

von Hippel-Lindau (VHL) disease is characterized by biallelic inactivation of the VHL gene leading to abnormal or absent VHL protein function, and constitutive activation of hypoxia-inducible factors (HIF) that leads to pro-tumorigenic signaling. Individuals with VHL disease develop numerous cysts and tumors involving multiple organs including the kidneys, central nervous system, endolymphatic sac, lungs, pancreatobiliary system, adrenal glands, epididymis, and/or broad ligament. On histologic examination, these lesions show morphologic overlap as they are frequently characterized by cells with clear cytoplasm and prominent vascularity. In addition to distinguishing non-renal tumors from metastatic clear cell renal cell carcinoma, understanding site-specific histopathologic and immunophenotypic features of these tumors has several applications. This includes distinguishing VHL-related tumors from those that arise sporadically and lack VHL gene alterations, guiding further genetic workup, and helping distinguish between different genetic predisposition syndromes. In this context, immunohistochemical studies for markers such as paired box 8 (PAX-8), carbonic anhydrase 9 (CA9), and glucose transporter 1 (GLUT-1) have an important role in routine clinical practice and represent cost-effective diagnostic tools. The recent development of targeted therapeutics directed against HIF-mediated signaling represents a significant milestone in the management of VHL disease and highlights the importance of accurately diagnosing and characterizing the wide spectrum of VHL disease-associated lesions.

Targeting HIF-2 Alpha in Renal Cell Carcinoma

OPINION STATEMENT

Current treatment options for patients with metastatic renal cell carcinoma (mRCC) are limited to immunotherapy with checkpoint inhibitors and targeted therapies that inhibit the vascular endothelial growth factor receptors (VEFG-R) and the mammalian target of rapamycin (mTOR). Despite significantly improved outcomes over the last few decades, most patients with mRCC will ultimately develop resistance to these therapies, thus highlighting the critical need for novel treatment options. As part of the VHL-HIF-VEGF axis that rests at the foundation of RCC pathogenesis, hypoxia-inducible factor 2α (HIF-2α) has been identified as a rationale target for mRCC treatment. Indeed, one such agent (belzutifan) is already approved for VHL-associated RCC and other VHL-associated neoplasms. Early trials of belzutifan indicate encouraging efficacy and good tolerability in sporadic mRCC as well. The potential inclusion of belzutifan and other HIF-2α inhibitors into the mRCC treatment armamentarium either as a single agent or as combination therapy would be a welcome addition for patients with mRCC.

Neurological applications of belzutifan in von Hippel-Lindau disease

Von Hippel-Lindau (VHL) disease is a tumor predisposition syndrome caused by mutations in the VHL gene that presents with visceral neoplasms and growths, including clear cell renal cell carcinoma, and central nervous system manifestations, such as hemangioblastomas of the brain and spine. The pathophysiology involves dysregulation of oxygen sensing caused by the inability to degrade HIFα, leading to the overactivation of hypoxic pathways. Hemangioblastomas are the most common tumors in patients with VHL and cause significant morbidity. Until recently, there were no systemic therapies available for patients that could effectively reduce the size of these lesions. Belzutifan, the first approved HIF-2α inhibitor, has demonstrated benefit in VHL-associated tumors, with a 30% response rate in hemangioblastomas and ~30%-50% reduction in their sizes over the course of treatment. Anemia is the most prominent adverse effect, affecting 76%-90% of participants and sometimes requiring dose reduction or transfusion. Other significant adverse events include hypoxia and fatigue. Overall, belzutifan is well tolerated; however, long-term data on dosing regimens, safety, and fertility are not yet available. Belzutifan holds promise for the treatment of neurological manifestations of VHL and its utility may influence the clinical management paradigms for this patient population.

The road to systemic therapy in von Hippel-Lindau (VHL) disease: Are we there yet?

Pathogenic germline mutations in VHL gene cause von Hippel-Lindau (VHL) disease, an autosomal dominant hereditary cancer syndrome associated with high penetrance of benign and malignant neoplasms, including clear cell renal cell carcinoma (ccRCC), central nervous system haemangioblastomas (CNS-HB), retinal angiomas, phaeochromocytomas and pancreatic neuroendocrine tumours (pNET). Management of VHL disease involves lifelong radiological and biochemical surveillance, often leading to repeat surgical intervention causing significant morbidity and mortality. Systemic therapy that prevents or reduces the need for surgical intervention could improve clinical outcomes and quality of life for affected individuals. Belzutifan is a second-generation small molecule hypoxia-inducible factor 2α (HIF-2α) inhibitor recently approved by US and UK regulators for the treatment of VHL (disease)-associated ccRCC, CNS-HB and pNET. While this is a welcome step forward, it is vital that we consider in what circumstances these drugs are recommended and how they fit into the overall management of VHL disease. In this personal view article, we reflect on the history of the use of systemic therapy in localised VHL disease and consider open questions relating to the use of HIF-2α inhibitors, including the need to involve medical oncologists in the multidisciplinary team moving forward. Indeed, VHL disease is the perfect paradigm for similar settings in the future.

Hemangioblastomas and Other Vascular Origating Tumors of Brain or Spinal Cord

Hemangioblastomas (HBs) are highly vascularized, slow-growing, rare benign tumors (WHO grade I). They account for about 2% of intracranial neoplasms; however, they are the most common primary cerebellar tumors in adults. Another frequent seat is the spinal cord (2-10% of primary spinal cord tumors). HBs are constituted by stromal and capillary vascular cells; macroscopically, HBs appear as nodular tumors, with or without cystic components. Although most of the HBs are sporadic (57-75%), they represent a particular component of von Hippel-Lindau disease (VHL), an autosomal dominant syndrome with high penetrance, due to a germline pathogenic mutation in the VHL gene, which is a tumor suppressor with chromosomal location on the short arm of chromosome three. VHL disease determines a variety of malignant and benign tumors, most frequently HBs, renal cell carcinomas, pheochromocytomas/paragangliomas, pancreatic neuroendocrine tumors, and endolymphatic sac tumors. Up to 20% of cases are due to de novo pathogenic variants without a family history. Many epidemiologic details of these tumors, especially the sporadic forms, are not well known. The median age of patients with sporadic HBS is about 40 years. More than two-third of VHL patients develop one or more central nervous system HBs during their lifetime; in case of VHL, patients at first diagnosis are usually younger than the patients with sporadic tumors. The most common presenting signs and symptoms are related to increased intracranial pressure, cerebellar signs, or spinal cord alterations in case of spinal involvement. Magnetic resonance imaging is the gold standard for the diagnosis, assessment, and follow-up of HBs, both sporadic and syndrome-related; angiography is rarely performed because the diagnosis is easily obtained with magnetic resonance. However, the diagnosis of an asymptomatic lesion does not automatically result in therapeutic actions, as the risks of treatment and the onset of possible neurological deficit need to be balanced, considering that HBs may remain asymptomatic and have a static or slow-growing behavior. In such cases, regular follow-up can represent a valid therapeutic option until the patients remain asymptomatic. There are no actual pharmacological therapies that are demonstrated to be effective for HBs. Surgery represents the primary therapeutic approach for these tumors. Observation or radiotherapy also plays a role in the long-term management of patients harboring HBs, especially in VHL; in few selected cases, endovascular treatment has been suggested before surgical removal. This chapter presents a systematic overview of epidemiology, clinical appearance, histopathological and neuroradiological characteristics of central nervous system HBs. Moreover, the genetic and molecular biology of sporadic and VHL HBS deserves special attention. Furthermore, we will describe all the available therapeutic options, along with the follow-up management. Finally, we will briefly report other vascular originating tumors as hemangioendotheliomas, hemangiomas, or angiosarcomas.

The Clinical and Molecular Features in the VHL Renal Cancers; Close or Distant Relatives with Sporadic Clear Cell Renal Cell Carcinoma?

Von Hippel-Lindau (VHL) disease is an autosomal dominant inherited cancer syndrome caused by germline mutations in the VHL tumor suppressor gene, characterized by the susceptibility to a wide array of benign and malign neoplasms, including clear-cell renal cell carcinoma. Moreover, VHL somatic inactivation is a crucial molecular event also in sporadic ccRCCs tumorigenesis. While systemic biomarkers in the VHL syndrome do not currently play a role in clinical practice, a new promising class of predictive biomarkers, microRNAs, has been increasingly studied. Lots of pan-genomic studies have deeply investigated the possible biological role of microRNAs in the development and progression of sporadic ccRCC; however, few studies have investigated the miRNA profile in VHL patients. Our review summarize all the new insights related to clinical and molecular features in VHL renal cancers, with a particular focus on the overlap with sporadic ccRCC.

Systemic Therapy Development in Von Hippel-Lindau Disease: An Outsized Contribution from an Orphan Disease

Over the last several decades, an improved understanding of von Hippel-Lindau disease and its underlying biology has informed the successful development of numerous anti-cancer agents, particularly for the treatment of advanced renal cell carcinoma. Most recently, this has culminated in the first regulatory approval for a systemic therapy for VHL disease-associated neoplasms. This review will trace the clinical development of systemic therapies for VHL disease and additionally highlight anticipated challenges and opportunities for future VHL systemic therapy.

Current Systemic Treatments for the Hereditary Cancer Syndromes: Drug Development in Light of Genomic Defects

Advances in the genetic basis of different tumors have led to identification of tumor vulnerabilities that can be turn into targeted therapies. In this regard, PARP inhibitors cause synthetic lethality with tumors harboring BRCA1 or BRCA2 genetic alterations. On the other hand, tumors with microsatellite instability, either due to germline or sporadic alterations, are candidates for immune checkpoint inhibitors. Finally, patients with von Hippel-Lindau disease who carry a germline alteration in the VHL gene may benefit form belzutifan, a hypoxia-inducible factor 2 alpha inhibitor. Overall, research on the underlying pathological mechanisms of these tumors has provided new therapeutic opportunities that might be expanded to other sporadic tumors with similar biology.

Belzutifan for Renal Cell Carcinoma in von Hippel-Lindau Disease

BACKGROUND

Patients with von Hippel-Lindau (VHL) disease have a high incidence of renal cell carcinoma owing to VHL gene inactivation and constitutive activation of the transcription factor hypoxia-inducible factor 2α (HIF-2α).

METHODS

In this phase 2, open-label, single-group trial, we investigated the efficacy and safety of the HIF-2α inhibitor belzutifan (MK-6482, previously called PT2977), administered orally at a dose of 120 mg daily, in patients with renal cell carcinoma associated with VHL disease. The primary end point was objective response (complete or partial response) as measured according to the Response Evaluation Criteria in Solid Tumors, version 1.1, by an independent central radiology review committee. We also assessed responses to belzutifan in patients with non-renal cell carcinoma neoplasms and the safety of belzutifan.

RESULTS

After a median follow-up of 21.8 months (range, 20.2 to 30.1), the percentage of patients with renal cell carcinoma who had an objective response was 49% (95% confidence interval, 36 to 62). Responses were also observed in patients with pancreatic lesions (47 of 61 patients [77%]) and central nervous system hemangioblastomas (15 of 50 patients [30%]). Among the 16 eyes that could be evaluated in 12 patients with retinal hemangioblastomas at baseline, all (100%) were graded as showing improvement. The most common adverse events were anemia (in 90% of the patients) and fatigue (in 66%). Seven patients discontinued treatment: four patients voluntarily discontinued, one discontinued owing to a treatment-related adverse event (grade 1 dizziness), one discontinued because of disease progression as assessed by the investigator, and one patient died (of acute toxic effects of fentanyl).

CONCLUSIONS

Belzutifan was associated with predominantly grade 1 and 2 adverse events and showed activity in patients with renal cell carcinomas and non-renal cell carcinoma neoplasms associated with VHL disease. (Funded by Merck Sharp and Dohme and others; MK-6482-004 ClinicalTrials.gov number, NCT03401788.).

Immunochemical expression of fibroblast growth factor and its receptors in primary tumor cells of renal cell carcinoma

BACKGROUND

There is the evidence of the role of the fibroblast growth factor and its receptors (FGF/FGFR) signaling pathway in tumorogenesis of renal cell carcinoma (RCC). We conducted a study aimed at evaluating of FGF2, FGFR1, and FGFR2 expression in primary tumor cells and assessing of these molecules expression levels effect on the characteristics of the tumor process and prognosis of patients with RCC.

METHODS

Expression of FGF2, FGFR1, and FGFR2 was investigated in 65 primary RCC specimens by immuhistochemical staining using the appropriate antibodies. Expression levels were evaluated by the semi-quantitative method. A search for correlations of expression levels of investigated growth factors and receptors with RCC features and patients outcomes was performed.

RESULTS

Cytoplasm and membrane expression of FGF2, FGFR1, and FGFR2 was found in the primary tumor cells of RCC patients. FGF2 staining was detected in 60.0% of cases (44.2 ± 5.4 HS). It was noted higher frequency and intensity of FGFR2 expression (66.2%; 46.6 ± 6.3 HS) comparing with FGFR1 (32.3%; 7.5 ± 2.2 HS). The correlation was revealed between the investigated markers overexpression and Fuhrman grade G3-4, as well as features of advanced RCC (paranephric fat tumor invasion, venous wall tumor invasion, adrenal and liver metastases). FGFR2 overexpression showed negative influence on cancer-specific survival in univariate analysis, however, lost its predictive value in multivariable analysis.

CONCLUSION

Expression of FGF2 and its receptors was found on the surface and in the cytoplasm of RCC primary tumor cells and needs following investigations.

Intermixed arteriovenous malformation and hemangioblastoma: case report and literature review

We report the third presentation of an intermixed arteriovenous malformation and hemangioblastoma. The rare occurrence of the diagnostic histologic features of both a neoplasm and vascular malformation in a single lesion is more common in gliomas, as angioglioma, and is termed an 'intermixed' lesion. We review the literature concerning the developmental biology of each lesion, and potential interplay in the formation of an intermixed vascular neoplasm and vascular malformation. The roles of cellular origin, genetic susceptibility, favourable microenvironment, altered local gene expression and key regulatory pathways are reviewed. Our review supports angiography and genetic profiling in intermixed lesions to inform management strategies. Consideration should be given to multimodality therapeutic interventions as required, including microsurgical resection, stereotactic radiosurgery and further research to exploit emerging molecular targets.

Targeting β2-Adrenergic Receptors Shows Therapeutical Benefits in Clear Cell Renal Cell Carcinoma from Von Hippel-Lindau Disease

Von Hippel–Lindau (VHL), is a rare autosomal dominant inherited cancer in which the lack of VHL protein triggers the development of multisystemic tumors such us retinal hemangioblastomas (HB), CNS-HB, and clear cell renal cell carcinoma (ccRCC). ccRCC ranks third in terms of incidence and first in cause of death. Standard systemic therapies for VHL-ccRCC have shown limited response, with recurrent surgeries being the only effective treatment. Targeting of β2-adrenergic receptor (ADRB) has shown therapeutic antitumor benefits on VHL-retinal HB (clinical trial) and VHL-CNS HB (in vitro). Therefore, the in vitro and in vivo antitumor benefits of propranolol (ADRB-1,2 antagonist) and ICI-118,551 (ADRB-2 antagonist) on VHL^−/− ccRCC primary cultures and 786-O tumor cell lines have been addressed. Propranolol and ICI-118,551 activated apoptosis inhibited gene and protein expression of HIF-2α, CAIX, and VEGF, and impaired partially the nuclear internalization of HIF-2α and NFĸB/p65. Moreover, propranolol and ICI-118,551 reduced tumor growth on two in vivo xenografts. Finally, ccRCC patients receiving propranolol as off-label treatment have shown a positive therapeutic response for two years on average. In summary, propranolol and ICI-118,551 have shown antitumor benefits in VHL-derived ccRCC, and since ccRCCs comprise 63% of the total RCCs, targeting ADRB2 becomes a promising drug for VHL and other non-VHL tumors.

Von Hippel-Lindau Disease: Current Challenges and Future Prospects

Understanding of molecular mechanisms of tumor growth has an increasing impact on the development of diagnostics and targeted therapy of human neoplasia. In this review, we summarize the current knowledge on molecular mechanisms and their clinical implications in von Hippel-Lindau (VHL) disease. This autosomal dominant tumor syndrome usually manifests in young adulthood and predisposes affected patients to the development of benign and malignant tumors of different organ systems mainly including the nervous system and internal organs. A consequent screening and timely preventive treatment of lesions are crucial for patients affected by VHL disease. Surgical indications and treatment have been evaluated and optimized over many years. In the last decade, pharmacological therapies have been evolving, but are largely still at an experimental stage. Effective pharmacological therapy as well as detection of biomarkers is based on the understanding of the molecular basis of disease. The molecular basis of von Hippel-Lindau disease is the loss of function of the VHL protein and subsequent accumulation of hypoxia-inducible factor with downstream effects on cellular metabolism and differentiation. Organs affected by VHL disease may develop frank tumors. More characteristically, however, they reveal multiple separate microscopic foci of neoplastic cell proliferation. The exact mechanisms of tumorigenesis in VHL disease are, however, still not entirely understood and knowledge on biomarkers and targeted therapy is scarce.