onametostat (JNJ-64619178)

Indeed, the PRMT5 inhibitor, JNJ-64619178, reduced cell viability and SNRPD3 methylation in neuroblastoma cells with high SNRPD3 and MYCN expression...Third, this leads to balanced alterative splicing (AS) activitiy that is favorable to neuroblastoma. Together this forms as a therapeutic vulnerability where SNRPD3 perturbation or PRMT5 inhibitors are selectively toxic to neuroblastoma by conditionally disturbing splicing activity.

A tolerable dose of JNJ-64619178 was identified in patients with LR MDS. However, no evidence of clinical benefit was observed.

P1, N=114, Active, not recruiting, Janssen Research & Development, LLC | Trial completion date: Dec 2023 --> Dec 2024 | Trial primary completion date: Dec 2023 --> Dec 2024

JNJ-64619178 demonstrated manageable dose-dependent toxicity and preliminary evidence of antitumor activity in ACC and other tumor types. Plasma exposure was dose dependent, and target inhibition was maintained with intermittent and continuous dosing. Based on safety, clinical activity, PK, and PD findings, two provisional RP2Ds were selected: 1.5 mg intermittently and 1.0 mg once daily. Aside from ACC, clinical benefit was limited, and biomarkers to enrich for responsiveness to PRMT5 inhibition will be needed for further development.

It targets NED induced by FIR in prostate cancer cells. JNJ-64619178 can radiosensitize and suppress NED induced by FIR in prostate cancer cells and can be a potential radiosensitizer for prostate cancer treatment.

We validated the synergistic effects and mechanisms of combined treatment with a type I PRMT inhibitor and a PRMT5 inhibitor (JNJ-64619178, GSK3326595/EPZ015938 or an in-house PRMT5i) using cell-based assays and in vivo studies...In vitro and in vivo studies revealed that inhibitors of type I PRMT and MAT2A (AG-270) dosing combination indeed exhibited stronger anti-cancer activity than mono-treatment...In vivo, the combination of type I PRMT inhibitor with different FLT3 inhibitors (Gilteritinib, Midostaurin, or CTS2016) led to deeper antitumor responses in a variety of FLT3-ITD AML models. Taken together, these findings support the co-administration of type I PRMT inhibitor with various therapies including epigenetic reprogramming, cancer metabolism modulation, or targeted therapies for receptor tyrosine kinases, which could benefit cancer patients as a promising therapeutic strategy.

Furthermore, we demonstrate that the clinical-stage PRMT5 inhibitor JNJ-64619178 potently and efficaciously inhibited CCSST cell growth in vitro and in vivo. These results provide new insights into PRMT5 as a transcription regulator and warrant JNJ-64619178 for further clinical development to treat CCSST patients.

Partial response has been seen in adenoid cystic carcinoma from both GSK3326595 and JNJ-64619178, with four cases of stable disease seen with PRT543. Highly significant is a durable complete response in isocitrate dehydrogenase 1-mutated glioblastoma multiforme with PRT811...Further studies are warranted, and there are clinical trials to come whose data will be telling of the efficacy of PRMT5 inhibitors in both hematologic and solid malignancies. The aim of this study is to compile available results of PRMT5 inhibitors in oncology clinical trials.

Pts had a median of 1 prior line of therapy post-ESA (range 0-4), including lenalidomide (33%), hypomethylating agents (29%), and luspatercept (19%). Despite robust target engagement, clinical activity was not observed, and enrollment was stopped. The role of PRMT5 in MDS and the differential impact of PRMT5 inhibition on normal and malignant hematopoiesis require further study.

An increase in splicing burden was observed upon JNJ-64619178 treatment. Overall, these observations support the continued clinical evaluation of JNJ-64619178 in patients with aberrant PRMT5 activity driven tumors.

Funding: Janssen Research & Development, LLC. Clinical trial identification: NCT03573310.

P1; N=70; Recruiting; Sponsor: Janssen Research & Development, LLC; Not yet recruiting --> Recruiting

P1; N=70; Not yet recruiting; Sponsor: Janssen Research & Development, LLC