RTID-01. A randomized study of low-intensity focused ultrasound for blood-brain barrier disruption for brain metastasis from non-small cell lung cancer (limitless)

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Conference Proceeding

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Blood-brain barrier disruption (BBBD) has been demonstrated, in preclinical models, to improve systemic drug delivery for BM. Low-intensity focused ultrasound (LIFU) with intravenously (IV) administered microbubble oscillators results in non-invasive BBBD, potentially permitting drug delivery. This randomized controlled trial (RCT) aims to determine the safety and efficacy of LIFU-mediated BBBD for NSCLC BM with immunotherapy.


LIMITLESS is an ongoing prospective, multicenter, parallel-arm, open-label RCT that randomizes patients with NSCLC-BM on pembrolizumab monotherapy prescribed as per standard-of-care to LIFU plus pembrolizumab (arm 1) or pembrolizumab alone (arm 2) in 2:1 ratio. Included patients have age ≥18 years, normal organ function, KPS≥70, EGFR- and ALK-negative primary tumor, and ≤3 BM, with ≥1 BM meeting measurable disease RANO-BM criteria. Patients on both arms receive standard-of-care therapy, while those on arm 1 also undergo LIFU before each dose of pembrolizumab (200 mg IV every 3 weeks). These patients undergo pre-treatment MRI brain, followed by IV administration of oscillating microbubbles for enhanced sonication. MR-guided BBBD is then performed using 220 kHz LIFU device with real-time acoustic feedback. Pembrolizumab is infused immediately thereafter, and repeat MRI done confirming BBB closure each cycle. Primary study endpoint is overall objective response rate (ORR) at 6 months as per RANO-BM criteria. Using a Bayesian design, a superior ORR of 60% is assumed for the LIFU arm versus 30% in the control arm for N = 96, 64 subjects in LIFU and 32 in control arm, for 80% power, with alpha = 0.05. For upper-bound estimate ORR of 45% in LIFU arm and 30% in control arm, the study needs N = 369 subjects; 246 in the LIFU arm and 123 in the control arm. Secondary outcomes are the best overall response rate and median time-to-response. Exploratory outcomes are median PFS, OS, intracranial PFS, extracranial PFS, and quality of life. Clinical trial information: NCT05317858.




Supplement 5

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SNO 2023 Annual Meeting. Society for Neuro-Oncology (SNO). November 15-19, 2023. Vancouver, Canada.

EANO 2023 Annual Meeting. European Association of Neuro-Oncology (EANO). September 21-24, 2023. Rotterdam, Netherlands



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