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4176 Tgrx-678 Penetrates Blood-Brain Barrier and Exhibits Preclinical Anti-Tumor Activity in Murine Ph+ CNS Leukemia and ALL Models

Program: Oral and Poster Abstracts
Session: 605. Molecular Pharmacology and Drug Resistance: Lymphoid Neoplasms: Poster III
Hematology Disease Topics & Pathways:
Research, Lymphoid Leukemias, ALL, Translational Research, Drug development, CML, Chronic Myeloid Malignancies, Diseases, Treatment Considerations, Lymphoid Malignancies, Myeloid Malignancies
Monday, December 9, 2024, 6:00 PM-8:00 PM

Yingying Zuo, PhD1*, Yun Liu, PhD1*, Meng Chen1*, Yixin Ai2*, Yanxia Shi, PhD3*, Jingrong Cao, PhD4 and Yihan Wang, PhD4*

1Department of Preclinical Management, Shenzhen TargetRx, Inc., Shenzhen, China
2Department of Computational Chemistry, Shenzhen TargetRx, Inc., Shenzhen, China
3Department of Biological and Translational Research, Shenzhen TargetRx, Inc., Shenzhen, China
4Shenzhen TargetRx, Inc., Shenzhen, China

Central nervous system leukemia (CNSL) relapse is relatively common among Philadelphia chromosome-positive (Ph+) acute lymphoblastic leukemia (ALL) and chronic myeloid leukemia (CML) lymphoid blast crisis patients. TGRX-678, a novel allosteric inhibitor specifically targeting ABL1 myristoyl pocket (STAMP), was previously reported to exhibit high potency against BCR::ABL1 WT and drug-resistant mutations in various in vitro and in vivo efficacy assays, and is currently being evaluated in a phase II clinical trial (NCT06453902). Herein we report the ability of TGRX-678 to penetrate blood-brain barrier in rats and the anti-tumor effects of TGRX-678 in murine CNS leukemia model and Ph+ ALL subcutaneous mouse model.

Sprague Dawley (SD) rats were given single dose of TGRX-678 at 50 mg/kg through oral gavage. Plasma and brain samples were collected at indicated time points post-dose and analyzed by liquid chromatography tandem mass spectrometry (LC-MS/MS) method. The maximum concentration (Cmax) and AUC0-last in brain of TGRX-678 were 1130 ng/g and 16346 hr*ng/g, respectively. The concentration ratio of brain to plasma was 0.44~0.74. For further validation, radio-labeled form [14C]-TGRX-678 was prepared and given single dose at 50 mg/100 µCi/kg to Sprague-Dawley (SD) and male Long-Evans (LE) rats. Liquid scintillation counter and quantitative whole-body autoradiography (QWBA) method were used to determine the radioactivity concentrations of plasma and brain, respectively. The results demonstrated high penetration of TGRX-678 into the brain tissue, with concentrations as high as 0.58~0.69-fold of those seen in the plasma (In male LE rat, 7131 ng Eq./g in plasma and 4885 ng Eq./g in brain at 0.5 hrs post-dose; 11981 ng Eq./g in plasma and 6950 ng Eq./g in brain at 4 hrs post-dose. In female SD rat, 15320 ng Eq./g in plasma and 9800 ng Eq./g in brain at 4 hrs post-dose; in male SD rat, 10656 ng Eq./g in plasma and 6400 ng Eq./g in brain at 4 hrs post-dose).

We then tested the anti-tumor effects of TGRX-678 in murine CNS leukemia models. Female NCG mice were injected with 2*105 K562-luciferase cells into the right common carotid artery. TGRX-678 (50mg/kg) was orally administrated once a day for 12 consecutive days. Bioluminescent signals, as the main index to evaluate tumor growth and drug efficacy, were monitored regularly by IVIS Lumina III (Perkin Elmer). TGRX-678 completely inhibited K562 cells proliferation in the brain (TGI=100.1% post 12-day dosing) and the drug was well tolerated. In Ph+ ALL subcutaneous mouse model, NCG mice were inoculated with SUP-B15 cells and orally dosed with TGRX-678 (5, 15, 45 mg/kg) once daily for 21 days. Tumor volumes and body weights were recorded 3 times a week. Tumor regression was observed in all three dose groups (TGI= 119.5%, 124.7%, 125.6% post 21-day dosing, respectively).

In conclusion, TGRX-678 can penetrate blood-brain barrier, and potently inhibit Ph+ leukemia cell growth in CNS and subcutaneous mouse model, suggesting TGRX-678’s potential therapeutic applications in patients with Ph+ CNS leukemia and ALL.

Disclosures: Zuo: Shenzhen TargetRx, Inc.: Current Employment, Current holder of stock options in a privately-held company. Liu: Shenzhen TargetRx, Inc.: Current Employment, Current holder of stock options in a privately-held company. Chen: Shenzhen TargetRx, Inc.: Ended employment in the past 24 months. Ai: Shenzhen TargetRx, Inc.: Current Employment, Current holder of stock options in a privately-held company. Shi: Shenzhen TargetRx, Inc.: Current Employment, Current holder of stock options in a privately-held company. Cao: Shenzhen TargetRx, Inc.: Current Employment, Current equity holder in private company, Other: COO of the company. Wang: Shenzhen TargetRx, Inc.: Current Employment, Current equity holder in private company, Membership on an entity's Board of Directors or advisory committees, Other: CEO of the company.

*signifies non-member of ASH