Abstract CT120: The randomized phase 1/2 LITESPARK-024 study of belzutifan with or without palbociclib in patients with advanced renal cell carcinoma (RCC)
Authors: McDermott David F. , Peer Avivit , Agarwal Neeraj , Atkins Michael B. , Cornell Jerry , Perini Rodolfo F. , Grossmann Kenneth F. , Gurney Howard 
Published: April 2023

Abstract
Background: First-line treatment with immunotherapy alone or in combination with antiangiogenic agents is a standard of care for advanced RCC. Many patients (pts) develop resistance to first-line treatment and effective second-line and beyond options are needed. The von Hippel-Lindau (VHL) gene is inactivated in approximately 90% of RCC cases, which results in the constitutive activation of hypoxia-inducible factor 2α (HIF-2α), a key oncogenic driver in RCC. The first-in-class HIF-2α inhibitor belzutifan has demonstrated promising antitumor activity with manageable safety in previously treated pts with advanced RCC. The cyclin-dependent kinase (CDK) pathway has also been implicated in RCC and is associated with poor clinical outcomes. In RCC cell lines, the CDK 4/6 inhibitor palbociclib inhibited cell growth. The addition of CDK 4/6 inhibition had synergistic antiproliferative effects with HIF-2α inhibition in HIF-2α-dependent VHL -/- RCC cell lines. Palbociclib could therefore potentially enhance the efficacy of belzutifan as combination therapy for previously treated pts with advanced RCC.
Methods: The two-part, open-label, multicenter, phase 1/2 randomized LITESPARK-024 study (NCT05468697) is intended to establish the recommended phase 2 dose (RP2D) of belzutifan + palbociclib in combination with a modified toxicity probability interval design (Part 1), followed by a direct comparison of belzutifan monotherapy to the combination with respect to safety and efficacy in pts with advanced RCC (Part 2). Pts with histologically confirmed unresectable stage IV RCC with a clear cell component, whose disease progressed on or after having received at least 2 systemic treatments (both an anti-PD-1/PD-L1 monoclonal antibody and a VEGF receptor-targeted tyrosine kinase inhibitor, in sequence or in combination), have measurable disease per RECIST v1.1 by blinded independent central review, and have KPS score of ≥70% will be enrolled. Up to 30 pts will be enrolled into 3 dose groups in Part 1 and will receive belzutifan 120 mg once daily + palbociclib (75, 100, or 125 mg) daily for 21 consecutive days followed by 7 days off. In part 2, approximately 150 pts will be randomly assigned 2:1 to receive belzutifan 120 mg once daily + palbociclib RP2D (21 consecutive days/7 days off) or belzutifan 120 mg once daily. Pts will be stratified by IMDC risk (0 vs 1-2 vs 3-6) and sarcomatoid histology (yes vs no) at randomization in part 2. The primary end point for part 1 is to assess dose-limiting toxicities and adverse events to determine the RP2D of belzutifan + palbociclib. The primary end point for part 2 is ORR per RECIST v1.1 by investigator assessment. Secondary end points for part 2 are CBR, DOR, PFS, OS, and safety and tolerability. This abstract was accepted and previously presented at the 2023 ASCO Genitourinary Cancers Symposium. All rights reserved.
Citation Format: David F. McDermott, Avivit Peer, Neeraj Agarwal, Michael B. Atkins, Jerry Cornell, Rodolfo F. Perini, Kenneth F. Grossmann, Howard Gurney. The randomized phase 1/2 LITESPARK-024 study of belzutifan with or without palbociclib in patients with advanced renal cell carcinoma (RCC) [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 2 (Clinical Trials and Late-Breaking Research); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(8_Suppl):Abstract nr CT120.