Study Background and Clinical Context
Renal cell carcinoma (RCC), particularly the clear-cell subtype, remains a significant global health challenge, accounting for approximately 2-3% of adult malignancies. Advanced RCC often presents with metastases, leading to poor prognosis and limited treatment options. Historically, immunotherapy agents such as cytokines had limited efficacy, but the advent of targeted therapies, including tyrosine kinase inhibitors (TKIs) like sunitinib, revolutionized management by improving progression-free and overall survival.
Despite these advances, the need for more effective and tolerable first-line options persists. Immunotherapies targeting PD-L1 and PD-1 pathways have shown promise in various cancers, including RCC, yet their potential remains underexplored. The combination of immune checkpoint blockade with anti-angiogenic agents is hypothesized to enhance anti-tumor efficacy through synergistic mechanisms. This trial investigates benmelstobart, a novel PD-L1 inhibitor, combined with anlotinib, a multi-target TKI, as a potential superior first-line therapy for advanced RCC.
Study Design and Methodology
The ETER100 trial was a multicenter, randomized, open-label, phase 3 study conducted across 37 sites in China, aiming to evaluate the efficacy and safety of benmelstobart plus anlotinib versus sunitinib in untreated advanced clear-cell RCC.
Eligible patients ranged from 18 to 80 years old, with no prior systemic therapy, an Eastern Cooperative Oncology Group (ECOG) performance status of 0 or 1, and adequate organ function. Patients were stratified by International Metastatic Renal Cell Carcinoma Database Consortium (IMDC) risk categories.
Participants were randomly assigned in a 1:1 ratio to receive either benmelstobart (intravenous, 1200 mg every three weeks) plus oral anlotinib (12 mg daily during the first 2 weeks of a 3-week cycle), or oral sunitinib (50 mg daily during the first 4 weeks of a 6-week cycle). The treatment continued until disease progression, intolerable toxicity, clinician decision, or withdrawal.
The primary endpoint was progression-free survival (PFS) assessed by blinded independent central review (BICR) according to RECIST v1.1 criteria. Secondary endpoints included overall response rate (ORR), overall survival (OS), and safety profiles.
Major Findings and Efficacy Results
Between August 2020 and February 2023, 687 patients were assessed; 531 were randomized, with 527 included in the full analysis set (FAS). The median age was 60 years, with a majority being male (76%) and Chinese nationals.
The median follow-up duration was approximately 23 months. The study demonstrated a significant improvement in PFS with benmelstobart plus anlotinib compared to sunitinib. In the FAS, median PFS was 19.0 months versus 9.8 months (hazard ratio [HR] 0.53; 95% CI 0.42-0.67; p<0.0001).
These results persisted in the per-protocol set (PPS), with median PFS of 19.0 versus 11.0 months; HR 0.55; 95% CI 0.43-0.70; p<0.0001.
The overall response rate was not detailed in the interim analysis, but the significant prolongation of PFS suggests robust anti-tumor activity.
Safety Profile and Adverse Events
The most common grade 3 or worse adverse event (AE) was hypertension, affecting 34% of patients in the benmelstobart-anlotinib group compared to 21% in the sunitinib group. Serious treatment-related adverse events (TRAEs) occurred in 24% versus 16%, with three treatment-related deaths (one each due to cardiac-respiratory arrest, renal failure, and an unspecified cause) in the combination group. No TRAE-related deaths occurred in the sunitinib group.
Overall, the safety profile was consistent with known toxicities of anti-angiogenic and immunotherapy agents, and the combination was deemed manageable with appropriate monitoring.
Clinical Implications and Future Perspectives
The trial’s findings suggest that benmelstobart combined with anlotinib offers a meaningful improvement in PFS compared to sunitinib, traditionally the standard first-line treatment for advanced clear-cell RCC. The encouraging efficacy, coupled with a manageable safety profile, positions this combination as a promising therapeutic option.
Further studies are warranted to evaluate long-term outcomes such as overall survival, quality of life, and biomarker-driven response prediction. Moreover, the potential for integrating this regimen into international guidelines could substantially alter the management landscape for RCC.
Limitations and Considerations
As an interim analysis from a Chinese-only cohort, the results may have limited generalizability globally. The open-label design could introduce bias; however, PFS assessed by blinded independent review mitigates this. Long-term data, including OS, are awaited to confirm sustained benefits.
Conclusion
This phase 3 trial demonstrates that the combination of benmelstobart and anlotinib significantly prolongs progression-free survival in previously untreated advanced clear-cell RCC compared to sunitinib. This innovative approach merits further investigation and could reshape first-line treatment strategies for this aggressive malignancy.
Funding and Trial Registration
The study was funded by Chia Tai Tianqing Pharmaceutical Group and the CSCO Clinical Oncology Research Foundation. It is registered under ClinicalTrials.gov (NCT04523272).
