JL4083

JL4083 is an investigational small molecule antiviral drug developed by Sichuan Jianlin Pharmaceutical for the treatment of influenza A and B. It functions as a cap-dependent endonuclease (CEN) inhibitor, targeting the polymerase acidic (PA) subunit of the viral RNA polymerase complex. By inhibiting the 'cap-snatching' process—a critical step where the virus acquires a 5' cap from host pre-mRNA to initiate its own transcription—JL4083 effectively halts viral replication. This mechanism is similar to that of baloxavir marboxil, offering a potent alternative to neuraminidase inhibitors and potentially addressing strains resistant to older antiviral classes. As of 2024, the drug is undergoing Phase 2 clinical trials in China.