Highlights from

ASH 2020

62nd Annual Meeting & Exposition of the American Society of Hematology

Virtual 5 - 8 December 2020

Sutimlimab offers a new therapy option for immune thrombocytopenia

A small phase 1 trial investigating the use of sutimlimab in patients with chronic immune thrombocytopenia (ITP) has yielded promising results [1]. A rapid and durable response was elicited and maintained, with an acceptable safety profile.

Some patients with ITP show only a partial response or no response at all to currently approved treatment protocols. In vitro data suggests that the classical complement pathway is the primary mechanism of thrombocytopenia in some patients. The humanised monoclonal antibody sutimlimab can inhibit complement pathway activation.

Dr Catherine Broome (MedStar Georgetown University Hospital, Washington DC, USA) reported the results of an open-label phase 1 trial which enrolled 12 patients. All were adults with chronic (>1 year) severe ITP who had shown only partial response to ≥2 previous treatment protocols. The trial consisted of 2 parts; in the first part, participants received sutimlimab on days 0 and 7, after which they received the medication biweekly for a maximum of 21 weeks. Next came a 9-week washout phase. If a clinically meaningful response (i.e. an elevation in platelet count) was elicited from the first part of the trial, the patient was deemed eligible for the second part of the trial (a long-term extension phase).

While 7 patients successfully completed the first part of the trial, 4 had to be removed because they either needed rescue therapy or they were unresponsive to sutimlimab. Only 6 patients enrolled in the second part of the trial, which lasted for a mean duration of 55 weeks.

In the first part of the trial, 9 of the 12 patients experienced 62 adverse events; 2 experienced a total of 3 serious treatment-emergent adverse events. Only 1 of these (migraine) was judged to be potentially related to sutimlimab. In the second part of the trial, 6 patients experienced a total of 51 adverse events. No deaths or thromboembolic events occurred during this study, and no participant discontinued sutimlimab therapy because of adverse events.

Researchers assert that these results provide further evidence that the complement pathway plays a role in some ITP patients, and that this treatment approach needs to be further explored.

  1. Broome C et al. Long-Term Safety and Efficacy of Sutimlimab in Patients with Chronic immune Thrombocytopenia. 62nd ASH Annual Meeting, 5-8 December 2020. Abstract 23.

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