Spring Bank Pharmaceuticals announced interim top-line results at 12 weeks from the first cohort of the ongoing Phase 2 trial evaluating the safety, efficacy and pharmacodynamics of escalating doses (50mg, 200mg and 400mg) of the investigational compound inarigivir co-administered with Gilead Sciences’ Vemlidy® (tenofovir alafenamide 25mg) for the treatment of chronic hepatitis B virus (HBV) infection. This is the first data from a clinical trial examining the co-administration of inarigivir with a nucleoside analog (NUC) in chronic HBV patients.
“We are impressed by the top-line results from the first cohort of the clinical trial examining the co-administration of the low dose of inarigivir 50mg and the nucleoside analog, Vemlidy®,” said Martin Driscoll, chief executive officer of Spring Bank. “We are very encouraged that these preliminary results suggest the addition of a low dose of inarigivir to a NUC therapy in chronic HBV patients could enhance the size of the HBsAg responder population as compared to the experience with the 50mg monotherapy dose in our completed Phase 2 ACHIEVE dose escalation trial. We look forward to the data from the higher dose cohorts of this trial and our ongoing CATALYST Phase 2b studies evaluating longer durations of treatment with inarigivir monotherapy and co-administered with a NUC that could further expand the chronic HBV responder population with the goal to significantly elevate functional cure rates for HBV patients.”
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In this Phase 2 trial, 30 patients with HBV infection received low-dose inarigivir 50mg plus Vemlidy for 12 weeks and 12 patients with HBV infection received Vemlidy alone for 12 weeks. Both arms will continue to receive Vemlidy alone for an additional 36 weeks. Interim top-line results from the first cohort indicate that, at week 12, 7 of the 30 patients in the inarigivir 50mg plus Vemlidy arm were HBsAg responders and met the primary efficacy study endpoint of having greater than or equal to 0.5 log₁₀ IU/mL reduction in HBsAg from baseline. When excluding patients showing signs of an ALT flare prior to entering the study, 5 of the remaining 28 patients in this arm were HBsAg responders at week 12. In the inarigivir 50mg monotherapy cohort of the completed Spring Bank Phase 2 ACHIEVE trial, only 1 of 14 patients was a HBsAg responder at week 12.
In the Vemlidy arm of this Phase 2 trial, 3 of the 12 patients were HBsAg responders. When excluding patients showing signs of an ALT flare prior to entering the study, only 1 of the remaining 10 patients in this arm was a HBsAg responder at week 12.
The co-administration of inarigivir 50mg and Vemlidy was generally safe and well tolerated with no serious adverse events observed over the 12-week treatment period. Treatment-emergent adverse events ranged from mild to moderate in severity.
Further analysis of the inarigivir 50mg plus Vemlidy cohort and evaluation of the safety, efficacy and pharmacodynamics of escalating doses of inarigivir (200mg and 400mg) co-administered with Vemlidy in HBV patients are ongoing. Interim top-line results from the remaining cohorts of the trial are expected in 2020.