Tenofovir Exalidex (TXL™)

TXL (formerly CMX157) is an oral pro-drug of the nucleotide analog, tenofovir. Other pro-drugs of tenofovir, tenofovir disoproxil fumarate (TDF, Viread) and tenofovir alafenamide fumarate (TAF, Vemlidy), are potent inhibitors of hepatitis B virus (HBV) replication and HIV-1 replication. TXL inhibits HBV replication in chronically infected HBV patients at doses substantially lower than TDF. TXL is expected to be similar to other nucleos(t)ide analog drugs in decreasing circulating HBV to undetectable levels in a majority of patients. The potent anti-viremia reduces progression of liver disease, but does not halt disease, as nucleos(t)ide analogs usually fail to eradicate HBV from the liver. Patients on active drug treatment are still at higher risk of developing HCC than individuals who were never infected with HBV. Nevertheless, this class of antiviral compounds will continue to be a mainstay of anti-HBV management for years to come. Studies suggest that TXL has an important advantage over other tenofovir pro-drugs – preferential uptake and utilization of TXL by the liver with expected minimization of off-target effects (e.g., reduced bone and renal safety issues). Thus, data have far shown TXL to be equally efficacious as the best anti-HBV medications currently on the market with the additional potential benefit of producing less frequent and/or less severe side effects.