Roche has posted an interim look at a phase 3 trial assessing the prophylactic use of its hemophilia A candidate emicizumab in kids. The study linked the bispecific antibody to a clinically meaningful decline in the number of bleeds after 12 weeks and appears to be free of the safety concerns that have dogged other studies of the drug.
Basel, Switzerland-based Roche plans to enroll 40 children aged 12 years and younger—plus potentially adolescents who meet certain criteria—in the single-arm trial and track the effect of once-weekly administration of emicizumab over 52 weeks. At the interim review, the participants, each of whom has inhibitors to factor VIII, had received the drug for a median of 12 weeks.
Befitting the interim nature of the review, Roche provided scant details on how the patients are responding to the drug. But what it did share suggests the trial is progressing as hoped. Prophylactic use of emicizumab shows a clinically meaningful reduction in the number of bleeds so far. Roche said the findings to date are consistent with its first phase 3, which ultimately linked use of the drug to a statistically significant decline in bleeds over time in adults and adolescents.
Roche is looking to the second phase 3—called HAVEN 2—to show emicizumab delivers similar improvements in children, while avoiding the safety questions that have blighted the other study. Clinical trials of emicizumab have reported several cases of thrombotic microangiopathy, including one implicated in the death of a patient earlier this year. The investigator pointed to a rectal hemorrhage as the cause of the death and absolved emicizumab of responsibility, but the rate of adverse events has raised doubts about whether the drug will deliver on its blockbuster potential.
The limited look at the safety of emicizumab in HAVEN 2 suggests the trial has yet to run into such problems. Roche listed injection site reactions and nasopharyngitis—inflammation of the mucous membranes—as the most common adverse events. The Swiss Big Pharma made no mention of any other adverse events.
Roche plans to include interim data from the study alongside results from HAVEN 1 in regulatory filings. The company is also working on two other trials to build out the case in support of the drug. Those trials, HAVEN 3 and HAVEN 4, are assessing the effect of the drug in adolescents and patients who lack inhibitors against factor VIII.