ATRT-05. DNA DAMAGE REPAIR INHIBITOR LP-184 INHIBITS CELL GROWTH IN ATRT

Atypical teratoid rhabdoid tumor (ATRT) is a rare, aggressive pediatric brain tumor. It is characterized by inactivation of SMARCB1 gene. There is currently no standard of care for treatment. LP-184 is an analog of acylfulvene. LP-184 induces cell-cycle arrest and cell apoptosis through alkylation of DNA and RNA. Previously, LP-184 was shown to have preclinical efficacy in temozolomide-resistant human glioblastoma cell lines. Additionally, it was reported that loss of SMARB1 increases sensitivity to LP-184. Therefore, we hypothesized that LP-184 may be effective against ATRTs. We have evaluated the effect of LP-184 in multiple ATRT cell lines, including CHLA06, CHLA266, and BT37. Treatment with LP-184 showed that LP-184 inhibits cell growth from 10nM to 200nM concentrations in an ATRT cell line (CellTiter Blue assay for BT37 p<0.0001 by t-test). We have identified an IC50 of 23.92nM. LP-184 induced apoptosis 96 hours after treatment in several ATRT cell lines as demonstrated by immunofluorescence for cleaved caspase-3 (CHLA06 p=0.0003 50nM vs DMSO, CHLA266 p=0.002 50nM vs DMSO, BT37 p=0.0014 50nM vs DMSO by t-test) and Western blot for c-PARP. LP-184 decreased proliferation 96 hours after treatment in several ATRT cell lines as demonstrated by immunofluorescence for Bromodeoxyuridine (BrdU) and Western blot for p-RB. Further evaluations of LP-184 treatment in vitro and in vivo are underway. Our in vitro data so far suggests that LP-184 is an effective potential therapeutic option for ATRT.