Bendamustine
Treanda · Alkylator
Tumor lysis-mediated AKI is the principal risk; TMA is rare.
PRETMALYTE
ModerateOpen →
HIF-2α inhibitor
Belzutifan
Welireg · Belzu
A HIF-2α inhibitor whose on-target anemia and hypoxia define its profile — kidney injury is largely indirect.
MildHIF-2α inhibitor · approved 2021
VHL disease-associated RCCVHL disease-associated CNS hemangioblastomas / pancreatic NETAdvanced clear-cell RCC (previously treated)
Signature kidney injury
Prerenal / Hemodynamic AKI
Anemia is the most common on-target adverse event (the leading grade 3 event in pivotal trials) and hypoxia is frequent. Direct nephrotoxicity is not a prominent or well-quantified signal; renal function changes mostly reflect underlying RCC/nephrectomy status.
Source: Choueiri et al., NEJM 2024 (LITESPARK-005; anemia leading G3 event)
Mechanism of kidney injury
By suppressing HIF-2α–mediated erythropoietin transcription, belzutifan causes anemia (and consequent hypoxia/fatigue). Any renal compromise is mostly indirect — hemodynamic or related to reduced oxygen delivery — rather than a defined tubular or glomerular lesion. Many patients have a solitary or operated kidney from prior RCC surgery, so any superimposed insult (anemia-related hypoperfusion, volume depletion, contrast, other nephrotoxins) has outsized impact.
Clinical presentation
Anemia, hypoxia (sometimes requiring supplemental oxygen) and fatigue dominate. Serum creatinine is usually stable; renal changes typically reflect tumor burden or post-nephrectomy reduced nephron mass rather than drug tubulotoxicity.
Onset
Anemia and hypoxia develop over the first weeks of therapy.
Reversibility
Reversible
Anticancer mechanism
First-in-class oral inhibitor of hypoxia-inducible factor-2α (HIF-2α). In VHL-deficient clear-cell renal cell carcinoma (ccRCC), loss of the von Hippel-Lindau protein stabilizes HIF-2α, which drives transcription of VEGF, cyclin D1, EPO and other pro-tumor/angiogenic genes; belzutifan blocks HIF-2α from dimerizing with HIF-1β/ARNT, shutting down this program in ccRCC and VHL-disease–associated tumors.
Management
Dose-modify or hold for severe anemia/hypoxia (from 120 mg daily); transfuse/ESA support as needed; supplemental oxygen for hypoxia. Monitor renal function closely in patients with reduced functional renal mass.
Risk factors
- Solitary or operated kidney (reduced nephron mass)
- Baseline anemia or cardiopulmonary disease
- Volume depletion
- Concurrent nephrotoxins/contrast
Prevention
- Monitor hemoglobin and oxygen saturation regularly
- Erythropoiesis-stimulating agents or transfusion per anemia guidance
- Maintain hydration; minimize nephrotoxin/contrast exposure in reduced-nephron patients
Note · The dominant, well-characterized toxicities are anemia and hypoxia — direct on-target consequences of HIF-2α/EPO suppression — not direct nephrotoxicity. The renal profile is still emerging.
Clinical depth
Renal dose adjustment
No dose adjustment for mild-to-moderate renal impairment; severe impairment (eGFR <30) and ESKD are not well studied. Standard 120 mg once daily; modifications are driven by anemia and hypoxia rather than CrCl.
Dialyzability & ESKD dosing
Not characterized; belzutifan is highly protein-bound and primarily metabolized by UGT2B17/CYP2C19, so it is unlikely to be substantially removed by dialysis. No ESKD dosing guidance exists.
Differential diagnosis
Distinguish anemia-driven fatigue/hypoxia (the expected on-target effect) from cardiopulmonary or hemorrhagic causes; separate a creatinine change due to reduced post-nephrectomy nephron mass or volume depletion from any true drug-related lesion (rare).
Monitoring
- Hemoglobin at baseline and periodically (anemia is the signature toxicity)
- Oxygen saturation / assessment for hypoxia
- Serum creatinine in patients with solitary or operated kidneys
Key trials & series
- Choueiri et al., NEJM 2024 — LITESPARK-005 phase 3 (belzutifan vs everolimus in advanced ccRCC; registrational; anemia leading grade 3 event)
- Jonasch et al., NEJM 2021 — LITESPARK-004 (VHL-associated RCC)
- Iliopoulos et al., Lancet Oncol 2024 — LITESPARK-004 VHL CNS hemangioblastomas
Clinical pearls
- Belzutifan's signature toxicity is on-target anemia (suppressed EPO) — anticipate it, monitor hemoglobin, and support rather than reflexively stop the drug.
- Many recipients have a single working kidney from RCC surgery, so protect renal reserve aggressively.
- Hypoxia can occur even without anemia and may need supplemental oxygen; it is a mechanism-based, expected effect.
Where it strikes
Nephron segments
Vasculature / Endothelium
Glomerular & peritubular capillaries
Injury signatures
Prerenal / Hemodynamic AKI
Evidence
7 peer-reviewed references. Citation metadata via PubMed / NLM.
LandmarkBelzutifan versus Everolimus for Advanced Renal-Cell Carcinoma.Choueiri TK et al. · N Engl J Med 2024 · PMID 39167807LITESPARK-005 pivotal phase 3 registrational trial; anemia the leading grade 3 adverse event.PMIDInhibition of hypoxia-inducible factor-2α in renal cell carcinoma with belzutifan: a phase 1 trial and biomarker analysis.Choueiri TK et al. · Nat Med 2021 · PMID 33888901First-in-human trial establishing on-target EPO suppression → anemia/hypoxia as the mechanistic toxicity.PMIDBelzutifan for Renal Cell Carcinoma in von Hippel-Lindau Disease.Jonasch E et al. · N Engl J Med 2021 · PMID 34818478LITESPARK-004 registrational VHL-associated RCC trial documenting anemia as the dominant toxicity.PMIDBelzutifan for patients with von Hippel-Lindau disease-associated CNS haemangioblastomas (LITESPARK-004): a multicentre, single-arm, phase 2 study.Iliopoulos O et al. · Lancet Oncol 2024 · PMID 39284337Phase 2 trial documenting the safety profile (anemia most common grade 3 event).PMIDHealth-related quality of life with belzutifan versus everolimus for advanced renal cell carcinoma (LITESPARK-005): patient-reported outcomes from a randomised, open-label, phase 3 trial.Powles T et al. · Lancet Oncol 2025 · PMID 40112850LITESPARK-005 patient-reported tolerability companion analysis.PMIDBelzutifan-Associated Hypoxia: A Review of the Novel Therapeutic, Proposed Mechanisms of Hypoxia, and Management Recommendations.Kucharczyk J et al. · Int J Mol Sci 2025 · PMID 40806229Focused review of belzutifan's on-target anemia/hypoxia and its management.PMIDTargeting HIF-2α: the role of belzutifan in clear cell renal carcinoma management.Valdés A et al. · Expert Rev Clin Pharmacol 2024 · PMID 39670660Mechanism and toxicity review emphasizing anemia and hypoxia as on-target effects.
Related agents
Other agents sharing the same signature kidney injury.