Abstract 5109: Novel acylfulvene LP184 shows single agent and combinatorial efficacy with PARP inhibitors in atypical teratoid rhabdoid tumors

Abstract Atypical Teratoid Rhabdoid Tumor (AT/RT) is an aggressive form of pediatric brain cancer that spreads quickly and leads to survival rates of less than 40%. Current treatments are insufficient at reducing this poor prognosis. A hallmark feature of ATRT is a SMARCB1 mutation. Illudins are a class of cytotoxic compounds with activity against pediatric solid tumors, including AT/RT. LP-184 is a novel synthetic illudin with improved brain penetration and activity against adult high-grade glioma orthotopic xenografts. We tested LP-184 against a battery of AT/RT cell lines including BT37, CHLA06, CHLA05, and CHLA266. LP-184 decreases viability at nanomolar concentrations with IC50s ranging from 9. 91nM - 23. 92nM. LP-184 decreased proliferation as measured by immunofluorescence and confirmed by western blots (BT37 p=0. 0001, CHLA06 =0. 0001, CHLA05=0. 033). LP-184 also induced apoptosis as demonstrated in immunofluorescent images and western blots (BT37 p=0. 0001, CHLA06 =0. 0001, CHLA05=0. 0015, CHLA266 p=0. 002). Furthermore, LP-184 shows strong synergy with the PARP inhibitor Rucaparib, suggesting that inhibition of DNA repair potentiates LP-184 activity. LP-184 reduces viable cell count by as much as 50% and combination with Rucaparib further decreases viability by 75% (BT37=0. 0001, CHLA06=0. 0002, CHLA05=0. 0077). The dual therapy also demonstrates cytostatic and cytotoxic effects as confirmed by immunofluorescence and western blots (BT37 BrdU = 0. 0004, BT37 CC3 = 0. 0002, CHLA06 BrdU = 0. 0033, CHLA06 CC3 = 0. 0117 compared to control). Further studies in vivo are being conducted to test single agent and combination therapies of LP-184 and Rucaparib in ATRT, as our data indicates that the two could provide a compelling treatment option for patients with this poor prognosis brain tumor. Citation Format: Abigail Tindall, Hyuk J. Kwon, Istabraq Musa, Tyler Findlay, Su Chan Lee, Charles Eberhart, Eric Raabe. Novel acylfulvene LP184 shows single agent and combinatorial efficacy with PARP inhibitors in atypical teratoid rhabdoid tumors abstract. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts) ; 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84 (6Suppl): Abstract nr 5109.