Imara's IMR-687, marketed under the brand name Tovinontrine, is an oral disease-modifying treatment for sickle cell disease (SCD) and β-thalassaemia. IMR-687 was developed to selectively block phosphodiesterase 9 (PDE9) in red blood cells, which in turn increases cyclic GMP levels, as a means to reactivate the production of foetal haemoglobin (HbF), a well-established modifier of disease severity. Findings from the interim analyses in the Phase IIb studies forces Imara to discontinue both the Ardent and Forte trials, as well as the further development of tovinontrine in SCD and beta-thalassaemia. While the treatment was generally well-tolerated, no meaningful benefit was achieved in the rate of vaso-occlusive crises (SCD), transfusion burden or improvement in most disease-related biomarkers (β-thalassaemia). The company is grateful to the patients, investigators and their teams for their participation in these trials and to the extended Imara team for their role and dedication in generating the comprehensive interim results. Additional information: press release.