SYST-12 LP-184, A NOVEL ACYLFULVENE-DERIVED TUMOR SITE ACTIVATED SMALL MOLECULE INHIBITS ADULT AND PEDIATRIC CNS TUMOR CELL GROWTH

Blood-brain barrier (BBB) permeable agents effective against recurrent, chemotherapy-resistant central nervous system (CNS) tumors are urgently needed, particularly in Glioblastoma multiforme (GBM) and atypical teratoid/rhabdoid tumors (ATRT). These represent extremely aggressive and lethal types of CNS malignancies. LP-184 is a next-generation acylfulvene class drug candidate and has received FDA orphan drug designations for the treatment of malignant gliomas and ATRT. LP-184 creates covalent DNA adducts that are selectively repaired via nucleotide excision repair (NER). Repair of LP-184-induced DNA damage is mediated by ERCC complexes. Consistent with this, we observed 3-6X decreased cancer cell viability in U87, M1123 and Mayo39 GBM cells treated with LP-184 in combination with the ERCC3 degrader Spironolactone (SP) relative to LP-184 alone. Mice bearing pre-established subcutaneous U87 xenografts were treated with SP alone, LP-184 alone or their combination. Tumors recurred after initial regression in 5/5 animals treated with LP-184 alone whereas tumors showed durable complete regression without recurrence in 4/5 animals treated with LP-184 + SP. Thus, LP-184 likely functions as a synthetically lethal agent in the presence of DNA repair deficiencies. LP-184 inhibited cell growth in CHLA06 and BT37 ATRT cell lines, with IC50s in the 20-25nM range. LP-184 induced apoptosis 96 hours after treatment in these ATRT cell lines as measured by immunofluorescence for cleaved caspase-3 and Western blot for c-PARP. LP-184 intravenous treatment at 4 mg/kg twice weekly for 2 weeks showed tumor regression in mice implanted with CHLA06 ATRT subcutaneous xenografts, with 112% tumor growth inhibition and 2/10 treated mice being tumor-free at study termination. LP-184 further showed favorable intracranial tumor bioavailability along with in vivo BBB permeability comparable to other CNS cancer drugs. These findings identify LP-184 as a promising new agent and support its further development for treating CNS tumors in adult and pediatric populations.