Phase I LITESPARK-001 study of belzutifan for advanced solid tumors: Extended 41-month follow-up in the clear cell renal cell carcinoma cohort

Belzutifan for the treatment of renal cell carcinoma

Belzutifan received its first FDA approval in 2021 for treating clinical manifestations of von Hippel-Lindau (VHL) disease including renal cell carcinoma (RCC) followed by approval in 2023 for treating advanced sporadic RCC that has progressed through multiple lines of treatment. It is the first FDA-approved drug to target hypoxia-inducible factor 2 alpha (HIF-2α). By inhibiting the HIF-2α transcription factor, belzutifan prevents HIF-2α from dimerizing with HIF-1β, thereby preventing the transcription of downstream oncogenes. Most clear cell renal cell carcinoma (ccRCC) tumors are associated with VHL deletion or inactivation resulting in HIF-2α overexpression that represents a key contributor to tumorigenesis, thereby making belzutifan a uniquely optimal drug for targeting ccRCC. Belzutifan has demonstrated activity in clinical trials as a front- and later-line therapy, and in combination with tyrosine kinase inhibitors. It has been largely well tolerated, although anemia represents a common on-target side effect and, along with hypoxia, requires monitoring during treatment. Ongoing phase III trials are investigating belzutifan in combination regimens in the relapsed/refractory, front-line, and adjuvant settings. Future studies will focus on identifying predictive biomarkers and resistance pathways.

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.

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.

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.

Cartilage Homeostasis under Physioxia

Articular cartilage receives nutrients and oxygen from the synovial fluid to maintain homeostasis. However, compared to tissues with abundant blood flow, articular cartilage is exposed to a hypoxic environment (i.e., physioxia) and has an enhanced hypoxic stress response. Hypoxia-inducible factors (HIFs) play a pivotal role in this physioxic environment. In normoxic conditions, HIFs are downregulated, whereas in physioxic conditions, they are upregulated. The HIF-α family comprises three members: HIF-1α, HIF-2α, and HIF-3α. Each member has a distinct function in articular cartilage. In osteoarthritis, which is primarily caused by degeneration of articular cartilage, HIF-1α is upregulated in chondrocytes and is believed to protect articular cartilage by acting anabolically on it. Conversely, in contrast to HIF-1α, HIF-2α exerts a catabolic influence on articular cartilage. It may therefore be possible to develop a new treatment for OA by controlling the expression of HIF-1α and HIF-2α with drugs or by altering the oxygen environment in the joints.

Rationale for immune checkpoint inhibitors plus targeted therapy for advanced renal cell carcinoma

Renal cell carcinoma (RCC) is a frequent urological malignancy characterized by a high rate of metastasis and lethality. The treatment strategy for advanced RCC has moved through multiple iterations over the past three decades. Initially, cytokine treatment was the only systemic treatment option for patients with RCC. With the development of medicine, antiangiogenic agents targeting vascular endothelial growth factor and mammalian target of rapamycin and immunotherapy, immune checkpoint inhibitors (ICIs) have emerged and received several achievements in the therapeutics of advanced RCC. However, ICIs have still not brought completely satisfactory results due to drug resistance and undesirable side effects. For the past years, the interests form researchers have been attracted by the combination of ICIs and targeted therapy for advanced RCC and the angiogenesis and immunogenic tumor microenvironmental variations in RCC. Therefore, we emphasize the potential principle and the clinical progress of ICIs combined with targeted treatment of advanced RCC, and summarize the future direction.

Belzutifan, HIF-2α Inhibitor, and Clear Cell Renal Cell Carcinoma With Somatic Von-Hippel-Lindau Loss-of-Function Mutation

The Von-Hippel-Lindau (VHL) gene, acting as a tumor suppressor, plays a crucial role in the tumorigenesis of clear cell renal cell carcinoma (ccRCC). Approximately 90% of individuals with advanced ccRCC exhibit somatic mutations in the VHL gene. Belzutifan, orally administered small-molecule inhibitor of hypoxia-induced factor-2α, has demonstrated promising efficacy in solid tumors associated with germline loss-of-function mutations in VHL, including ccRCC. However, its impact on cases with somatic or sporadic VHL mutations remains unclear. Here, we present 2 cases where belzutifan monotherapy was employed in patients with advanced ccRCC and somatic loss-of-function mutations in VHL. Both patients exhibited a swift and sustained response, underscoring the potential role of belzutifan as a viable option in second or subsequent lines of therapy for individuals with somatic VHL mutations. Despite both patients experiencing a pulmonary crisis with respiratory compromise, their rapid response to belzutifan further emphasizes its potential utility in cases involving pulmonary or visceral crises. This report contributes valuable insights into the treatment landscape for advanced ccRCC with somatic VHL mutations.