(UroToday.com) The 2023 European Society of Medical Oncology (ESMO) Annual Congress held in Madrid, Spain between October 20th and 24th, 2023 was host to a non-prostate genitourinary proffered paper session. Dr. Neeraj Agarwal presented the results of the phase II LITESPARK-013 study that evaluated the safety and efficacy of two doses of belzutifan in patients with advanced renal cell carcinoma (RCC).
Constitutively active Hypoxia Inducible Factor (HIF-2a) is a key oncogenic driver in clear cell RCC. The first-in-class oral HIF-2a inhibitor belzutifan is approved for the treatment of von Hippel-Lindau disease-associated RCC, central nervous system hemangioblastomas, and/or pancreatic neuroendocrine tumors not requiring immediate surgery based on results of the phase 2 LITESPARK-004 study.1 Belzutifan has also show anti-tumor activity in patients with previously treated advanced clear cell RCC in the phase 1 LITESPARK-001 study. In this study, belzutifan doses from 20 mg to 240 mg were evaluated. The maximum tolerated dose of belzutifan was not reached. Belzutifan 120 mg orally once daily was selected as the recommended phase 2 dose based on the totality of safety, pharmacokinetics, and pharmacodynamics data.2
The phase 2 LITESPARK-013 study compared belzutifan 200 mg and 120 mg doses in patients with advanced clear cell RCC that progressed on anti-PD-1/L1 therapy in order to evaluate the safetv and efficacv of these 2 doses in a larger, randomized trial. In this report, Dr. Agarwal presented the safety and efficacy results from LITESPARK-013 after a median follow-up of 20.1 months.
LITESPARK-013 (NCT04489771) included patients with histologically confirmed advanced/metastatic clear cell RCC who received 3 or less prior systemic therapy regimens for advanced/metastatic disease. Importantly, patients had received only 1 prior anti-PD-1/L-1 therapy. Patients underwent 1:1 randomization, stratified by IMDC prognostic score and number of prior tyrosine kinase inhibitor (TKI) regimens for advanced RCC, into:
- Belzutifan 200 mg orally once daily (n=78)
- Belzutifan 120 mg orally once daily (n=76)
The primary endpoint was objective response rate (ORR), as assessed by blinded independent central review (BICR) using RECIST v1.1 criteria. The secondary endpoints included progression-free survival (PFS), duration of response (DOR), overall survival, and safety outcomes.
The median time from randomization to data cut-off was 20.1 months. There 21 and 18 patients receiving ongoing treatment in the 200 mg and 120 mg arms, respectively.
The baseline characteristics are summarized below. 82% of patients had IMDC intermediate-poor risk disease. 28% of patients had received no prior TKI regimens, with 51% and 21% having received 1 and 2-3 previous TKI regimens.
Overall, there were no significant differences in efficacy outcomes between the two dosage groups. The ORR was similar in both arms at 23.1 – 23.7%. We do note that 4 patients (5.1%) in the belzutifan 200 mg dose group had a complete response, compared to none in the 120 mg group.
The waterfall plots below summarizing the best percentage change from baseline in target lesions by BICR were comparable between the 2 dose groups:
Subgroup analysis further demonstrated comparable ORRs by BICR across the two dose groups:
The DOR was similar in both dose groups. The median time to response was identical at 3.6 months.
No clinically or statistically significant differences in PFS and OS were observed between the two dose groups.
While any-grade and grade 3-5 adverse events occurred with similar frequency in both dose groups (99% and 69%, respectively), adverse events leading to any dose modification occurred more frequently in the 200 mg group (58% versus 46%), as well as those leading to treatment discontinuation (14% versus 5%).
The most common treatment-related adverse events were anemia, fatigue, and hypoxia, with similar adverse event profiles/patterns in both dose groups.
Dr. Agarwal concluded that the efficacy outcomes of belzutifan 200 mg and 120 mg orally once daily were comparable.
The safety profiles of the belzutifan 200 mg and 120 mg once daily doses in the LITESPARK-013 study were generally similar and consistent with the known safety profile of belzutifan. However, the belzutifan 200 mg once daily dose was associated with a higher rate of overall dose modifications and drug discontinuation. These results, together with results from the phase 3 LITESPARK-005 study, continue to support the belzutifan 120 mg once dailv dose in patients with clear cell RCC.
Presented by: Neeraj Agarwal, MD, Professor, Department of Medicine, Huntsman Cancer Institute, University of Utah, Salt Lake City, UT
Written by: Rashid K. Sayyid, MD, MSc – Society of Urologic Oncology (SUO) Clinical Fellow at The University of Toronto, @rksayyid on Twitter during the 2023 European Society of Medical Oncology (ESMO) Annual Meeting, Madrid, Spain, Fri, Oct 20 – Tues, Oct 24, 2023.
References:
1. Jonasch E, et al. LITESPARK-004 (MK-6482-004) phase 2 study of belzutifan, an oral hypoxia-inducible factor 2α inhibitor (HIF-2α), for von Hippel-Lindau (VHL) disease: Update with more than two years of follow-up data. J Clin Oncol 2022;16:S4546-4546.