Spring Bank Pharmaceuticals, Inc. announced dosing of patients with inarigivir soproxil 400mg in two significant trials: the CATALYST 2 trial, examining the administration of inarigivir 400mg in nucleo(t)side (NUC)-suppressed chronic hepatitis B virus (HBV) patients, and a unique liver biopsy study examining paired liver biopsies in HBV patients before treatment and on treatment with inarigivir to identify the interaction of inarigivir 400mg with the intrahepatic immune system and its effect on cccDNA. Spring Bank also announces the expansion of a collaborative study in patients infected with chronic HBV involving the evaluation of multiple doses of inarigivir co-administered with tenofovir alafenamide 25mg to include the 400mg dose of inarigivir. The company broad phase 2 HBV clinical development program is designed to demonstrate the likelihood of functional cure in both HBV treatment-naïve and HBV suppressed patients on nucleotide treatment in the CATALYST 1 and CATALYST 2 trials, leading to the potential to initiate inarigivir Phase 3 studies in late 2020.  Spring Bank anticipates that it will begin dosing patients in the CATALYST 1 trial, a study examining the use of inarigivir 400mg as monotherapy and co-administered with tenofovir alafenamide 25mg daily in HBV treatment-naïve patients, in September. The principal investigator has successfully randomized and completed treatment in the first patient in the intra-hepatic liver biopsy study. This trial will evaluate both the immunology and virology of HBV directly in the liver and the corresponding response to inarigivir. “This exciting and unique study has the potential to determine how activating the innate immune system with inarigivir can reduce intra-hepatic viral burden and cccDNA reservoirs and is a critical scientific study for understanding the pathway to HBV cure,” said Dr. Antonio Bertoletti, a member of the Spring Bank Scientific Advisory Board and the Principal Investigator of the study at Duke–NUS Medical School in Singapore. Additionally, the ongoing collaborative trial examining multiple ascending doses of inarigivir co-administered with tenofovir alafenamide 25mg for 12 weeks has been expanded to include a new cohort of chronic HBV patients receiving inarigivir 400mg daily with tenofovir alafenamide 25mg daily. “The results of this study and CATALYST trials will enable Spring Bank to make a decision on the future strategy for a Phase 3 inarigivir program across multiple patient groups in 2020,” said Mr. Driscoll. The company has launched two Phase 2 global trials (CATALYST 1 and CATALYST 2) examining the administration of inarigivir 400mg as monotherapy and co-administered with a NUC in naïve and virally-suppressed chronic HBV patients. The CATALYST trials include multiple patient cohorts with dosing periods to include 12 weeks, 24 weeks, and 48 weeks. These trials are designed to demonstrate the likelihood of functional cure, and Spring Bank could be in a position to reveal functional cure data from one or more of these trials in 2020. In addition, there is an ongoing Phase 2 trial examining the co-administration of inarigivir 50mg and tenofovir alafenamide 25mg in chronic HBV patients, the co-administration of inarigivir 200mg and tenofovir alafenamide 25mg in chronic HBV patients, the co-administration of inarigivir 400mg and tenofovir alafenamide 25mg in chronic HBV patients and the administration of inarigivir 100mg in virally-suppressed patients who currently are and continue to be treated with a NUC.