Reference Detail

Ref Type

abstract

PMID

Authors

Meagan B Ryan; Chun Li; Yongxin Han; Klaus P Hoeflich; Michael R Hale; Margit Hagel

Title

Abstract A089: NST-628 is a potent, fully brain-penetrant, RAS/MAPK pathway molecular glue inhibitor with efficacy in CNS tumor models

Journal	Vol	Issue	Date	Pages	Journal Short Title
	22	12_supplement	2023		Mol Cancer Ther

URL

https://aacrjournals.org/mct/article/22/12_Supplement/A089/730457

Abstract Text

Alterations in the RAS/RAF/MEK/ERK signaling cascade are common across multiple solid tumor types and aberrant signaling of the pathway is a driver for RAS- and RAF-driven cancers. Apart from approved mutation selective inhibitors for BRAF Class I and KRAS G12C mutations, other mutations of RAS and RAF are not directly addressable by currently approved inhibitors and there is a need for inhibitors with superior efficacy, durability and tolerability for the MAPK pathway in RAS- and RAF-driven cancers. Currently approved inhibitors of the RAS-MAPK pathway also have limited central nervous system (CNS) exposure and an area of significant unmet patient need exists for patients with primary and metastatic tumors harboring RAS-MAPK pathway alterations. NST-628 has CNS permeability, with a Kpu,u >1, that is far higher than trametinib or VS-6766 (Kpu,u of 0.11 and 0.18 respectively). The predicted effective human half-life of NST-628 (~9h) is amenable to daily dosing in the clinic. In vivo, NST-628 leads to a dose-dependent inhibition of the MAPK pathway in murine brain tissue[KS1] as measured by phospho-ERK. In an intracranial luciferase-tagged SK-MEL-2 xenograft model (NRAS Q61R), NST-628 leads to tumor regressions with a daily dosing regimen (3 mg/kg QD). Tumor regressions as measured by bioluminescent imaging (BLI) were only seen with NST-628 (50%) in the SK-MEL-2 model, whereas trametinib and VS-6766 showed minimal efficacy due to low exposure in the CNS. In the NF-1 mutant MeWo (NF1 Q1336*) melanoma intracranial xenograft model (luciferase tagged), NST-628 led to tumor regressions at two dosing regimens (1, 3 mg/kg QD) and tumor stasis at lower doses (0.3 mg/kg) as measured by BLI. In contrast, the brain penetrant type II RAF inhibitor DAY101 (formerly TAK580) showed no efficacy in the MeWo model and resulted in paradoxical pathway hyper-activation, as determined by enhanced PD response and tumor growth. Only NST-628 effectively inhibited MAPK signaling as measured by DUSP6 transcript in a time- and dose-dependent manner. Overall, survival of mice harboring MeWo intracranial tumors was also significantly increased versus vehicle control and DAY101 treatment groups. These data collectively support best-in-class potential of NST-628 and initiation of clinical trials in patients with solid tumors harboring RAS- and RAF-mutations, including those presenting clinically with brain metastases and primary intracranial tumors.

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Molecular Profile	Treatment Approach

Gene Name	Source	Synonyms	Protein Domains	Gene Description	Gene Role

Therapy Name	Drugs	Efficacy Evidence	Clinical Trials

Drug Name	Trade Name	Synonyms	Drug Classes	Drug Description

Gene	Variant	Impact	Protein Effect	Variant Description	Associated with drug Resistance

Molecular Profile	Indication/Tumor Type	Response Type	Therapy Name	Approval Status	Evidence Type	Efficacy Evidence	References
NRAS Q61R	melanoma	predicted - sensitive	NST-628	Preclinical - Cell line xenograft	Actionable	In a preclinical study, NST-628 treatment resulted in tumor regression in an intracranial melanoma cell line xenograft model harboring NRAS Q61R (Mol Cancer Ther (2023) 22 (12_Supplement): A089).	detail...