Sobi announces topline phase III data of avatrombopag for the treatment of chemotherapy-induced thrombocytopenia.

Swedish Orphan Biovitrum AB (publ) (Sobi) announced topline results from its phase III study of avatrombopag, an oral thrombopoietin (TPO) receptor agonist, in solid tumour cancer patients with chemotherapy-induced thrombocytopenia (CIT). Though avatrombopag increased platelet counts relative to placebo as expected, the study did not meet the composite primary endpoint of avoiding platelet transfusions, chemotherapy dose reductions by 15 per cent or greater, and chemotherapy dose delays by four days or more. In the intent-to-treat population (full analysis set), 69.5 per cent and 72.5 per cent of avatrombopag and placebo subjects, respectively, were considered responders for the primary endpoint (p=0.72). In the per-protocol population, 85.0 per cent and 84.4 per cent of avatrombopag and placebo subjects, respectively, were considered responders for the primary endpoint (p=0.96). It was unexpected that the placebo subjects would have such a low incidence of dose delays and dose reductions and additional data analyses are ongoing to understand this observation. Topline adverse event data for avatrombopag reinforce the existing safety profile and were comparable to that of placebo in this population of cancer patients receiving myelosuppressive chemotherapy..