Regulated necrosis occurs in various pathophysiological conditions under oxidative stress. Here, we report that receptor-interacting protein kinase 1 (RIPK1), a key player in one type of regulated necrosis (necroptosis), also participates in another type of poly (ADP-ribose) polymerase 1 (PARP1)-dependent regulated necrosis (parthanatos). Various biological signatures of parthanatos were significantly attenuated in Ripk1 mouse embryonic fibroblasts, including PARylation, nuclear translocation of apoptosis-inducing factor, and PARP1-dependent cell death under HO exposure. Hence, we investigated whether RIPK1 regulates the activity of PARP1. RIPK1 activated PARP1 via an interaction with the catalytic domain of PARP1 in the nucleus. Of note, both wild type and kinase-dead mutant RIPK1 induced PARP1 activation and led to PARP1-mediated cell death upon HO insult, demonstrating the kinase-independent regulation of RIPK1 in PARP1 activation. Collectively, our results demonstrate the existence of a kinase-independent role of nuclear RIPK1 in the regulation of PARP1.

Parkinson's disease (PD), the second most common neurodegenerative disease, affects 1% of the population over the age of 60 worldwide. 1 Features of PD include the progressive loss of dopaminergic neurons in the substantia nigra and appearance of abnormal protein aggregates, including Lewy bodies (LBs), whose major component is α-synuclein. 2-4

Epilepsy is a neurological disorder with recurrent unprovoked seizures as the main symptom. Of the coumarin derivatives in Angelica gigas, decursin, a major coumarin component, was reported to exhibit significant protective activity against glutamate-induced neurotoxicity when added to primary cultures of rat cortical cells. This study served to investigate the effects of decursin on a kainic acid (KA)-induced status epilepticus model. Thirty minutes after intraperitoneal injections of decursin (20 mg/kg) in male 7-week-old C57BL/6 mice, the animals were treated with KA (30 mg/kg, intraperitoneally) and then examined for behavioral seizure score, electroencephalogram, seizure-related expressed protein levels, neuronal cell loss, neurodegeneration, and astrogliosis. KA injections significantly enhanced neurodegenerative conditions but treatment with decursin 30 min before KA injection reduced the detrimental effects of KA in mice. The decursin-treated KA-injected group showed significantly decreased behavioral seizure activity and remarkably attenuated intense and high-frequency seizure discharges in the parietal cortex for 2 h compared with the group treated only with KA. Furthermore, in-vivo results indicated that decursin strongly inhibits selective neuronal death, astrogliosis, and oxidative stress induced by KA administration. Therefore decursin is able to attenuate KA-induced seizures and could have potential as an antiepileptic drug.

α-Synuclein accumulation is implicated in the pathogenesis of neurodegenerative diseases, including Parkinson’s disease (PD). Previously, we reported that Fas-associated factor 1 (FAF1), which plays a role in PD pathogenesis, potentiates α-synuclein accumulation through autophagy impairment in dopaminergic neurons. In this study, we show that KM-819, a FAF1-targeting compound, which has completed phase I clinical trials, interferes with α-synuclein accumulation in the mouse brain, as well as in human neuronal cells (SH-SY5Ys). KM-819 suppressed the accumulation of monomeric, oligomeric, and aggregated forms of α-synuclein in neuronal cells. Furthermore, KM-819 restored the turnover rate of α-synuclein in FAF1-overexpressing SH-SY5Y cells, implicating KM-819-mediated reconstitution of the α-synuclein degradative pathway. In addition, KM-819 reconstituted autophagic flux in FAF1-transfected SH-SY5Y cells, also suppressing α-synuclein-induced mitochondrial dysfunction. Moreover, oral administration of KM-819 also interfered with α-synuclein accumulation in the midbrain of mice overexpressing FAF1 via an adeno-associated virus system. Consistently, KM-819 reduced α-synuclein accumulation in both the hippocampus and the midbrain of human A53T α-synuclein transgenic mice. Collectively, these data imply that KM-819 may have therapeutic potential for patients with PD.

LCB84 is a human Trop-2-targeting antibody drug conjugate (ADC) composed of monomethyl auristatin E (MMAE) as payload and the Hu2G10 (by Mediterranea Theranostic) humanized IgG1 antibody that selectively targets the ADAM10-activated Trop-2 protein selectively expressed in transformed cancer cells (1). LCB84 was prepared using ConjuAll࣪, a proprietary site-directed conjugation technology of LegoChem Biosciences, which incorporates a conjugation ‘handle’ joined by enzymatic prenylation to a specifically engineered recognition sequence (CaaX) on antibody light chains. This conjugation handle facilitates simple versatile chemical conjugation to the linker-payload. A proprietary plasma-stable cleavable linker that is recognized and cleaved by a cancer-associated lysosomal enzyme, β-glucuronidase, was used to enable efficient and traceless payload release in a cancer-specific manner. LCB84 has been evaluated for anti-tumor activity and showed superior anticancer efficacy in triple-negative breast cancer (TNBC), pancreatic ductal adenocarcinoma (PDAC), gastric cancer and non-small cell lung cancer (NSCLC) cell line-derived xenograft (CDX) models compared to the ADC competitors Trodelvy and DS-1062. The LCB84 treatments were well tolerated, with no changes in body weight compared to control animals, for all dosing groups. LCB84 has robust cross-reactivity against primate Trop-2, which allows rigorous toxicity studies in monkeys. Remarkably, preliminary toxicity studies using cynomolgus monkeys showed that LCB84 is well tolerated, with calculated therapeutic index (TI, MTD/MED) of ~30 for single dosing and ~40 for repeat dosing. In conclusion, LCB84 is highly effective against Trop-2-positive CDX models in mice at doses that are well tolerated in mice and in primate models. Use of this proprietary plasma-stable cancer-selective linker technology and the Hu2G10 anti-Trop-2 monoclonal antibody that targets cancer-activated Trop-2 has led to a greatly improved next generation ADC for the treatment of various Trop-2-positive solid cancers including TNBC, PDAC, NSCLC and gastric cancer. Citation Format: Hyejung Kim, Emanuela Guerra, Eunji Baek, Yeojin Jeong, Hyogeun You, Byeongjun Yu, Taeik Jang, Alberti Saverio, Chul-Woong Chung, Changsik Park. LCB84, a TROP2-targeted ADC, for treatment of solid tumors that express TROP-2 using the hu2G10 tumor-selective anti-TROP2 monoclonal antibody, a proprietary site-directed conjugation technology and plasma-stable tumor-selective linker chemistry [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 328.