Red blood cells
The oral SYK inhibitor fostamatinib can produce responses in patients with warm antibody autoimmune hemolytic anemia (AIHA), according to Rigel Pharmaceuticals, Inc.
The company reported topline results from the first stage of the phase 2 SOAR study, which showed that fostamatinib produced a 35% response rate.
A response was defined as achieving a hemoglobin level of greater than 10 g/dL and at least a 2 g/dL increase from baseline.
“Many patients with AIHA suffer from severe, debilitating disease that negatively affects their quality of life,” said David J. Kuter, MD, the director for the Center of Hematology at Massachusetts General Hospital in Boston and the lead investigator of the SOAR study.
“There are no FDA-approved medications for the treatment of AIHA, which means that those living with the condition are in need of new and effective therapeutic options.”
In the SOAR study, Dr Kuter and his colleagues are evaluating fostamatinib in patients with warm antibody AIHA who previously received at least 1 treatment but did not have a meaningful benefit and are still anemic.
The study utilizes an open-label, Simon 2-stage design to evaluate fostamatinib given at 150 mg twice daily.
Stage 1 has enrolled 17 patients who have had at least 1 post-baseline hemoglobin measure.
Four of these patients responded to fostamatinib during the 12-week evaluation period, and an additional 2 patients met response criteria in the extension study after 12 weeks of dosing.
So the overall response rate was 35% (6/17), although Rigel Pharmaceuticals said these data are preliminary and require further verification.
Two patients withdrew from the study early due to non-safety-related reasons and will be replaced per the study protocol.
According to Rigel Pharmaceuticals, the treatment-emergent adverse events (AEs) in this trial were consistent with the prior clinical experience with fostamatinib.
Treatment-emergent AEs—which included diarrhea, elevated liver function tests, and hypertension—were manageable and mostly mild or moderate in nature.
There were 2 deaths reported during the trial. Both were due to non-treatment-related serious AEs, according to investigators. One patient had skin necrosis and infection. The other was an elderly patient who had pneumonia and was immunosuppressed due to prior chronic lymphocytic leukemia and steroid use.
A third patient experienced a non-treatment-related serious AE but recovered and continued on treatment.
Rigel Pharmaceuticals said a comprehensive analysis of the data will continue and will be presented at a future scientific conference.
The company also intends to begin enrollment for stage 2 of this study, in which 20 patients will be enrolled under the same protocol.
