The Sanofi Phase II trial of selective JAK2 inhibitor (SAR302503) conducted in myelofibrosis (MF) patients has met its primary endpoint.
The treatment with investigational JAK2 inhibitor demonstrated reduced spleen size and improved constitutional symptoms in patients with intermediate-2 or high-risk primary or secondary MF.
Sanofi Oncology senior vice president and head Debasish Roychowdhury said the study confirms the once-daily oral administration of SAR302503 identified for use in the Phase III trial in the patient population.
"We believe SAR302503 could provide a benefit to these patients with primary and secondary myelofibrosis and we look forward to our Phase III results next year," Roychowdhury added.
The open label, randomised dose-ranging study evaluated the efficacy of once-daily oral doses of 300mg, 400mg, and 500mg of SAR302503 for the reduction of spleen volume.
Change in spleen volume at the end of cycle three assessed by MRI with independent central review is the primary endpoint of the study, while the secondary endpoints consist of spleen response, safety and symptom response using the MPN-SAF scale.
According to the data, the mean percentage reductions in spleen volume against baseline were 30%, 33% and 42% in each group respectively, while the proportion of patients who achieved a greater than or equal to 35% reduction in spleen volume by MRI was 30%, 50% and 63.6% in each group, respectively.
The proportion of patients who achieved greater than or equal to 50% reduction in the Myeloproliferative Neoplasm Symptom Assessment Form score was similar in all dose groups.
The results support the 400mg and 500mg doses selected for the SAR302503 Phase III JAKARTA trial. The trial enrolled 289 patients over nine months. Initial results are expected in the second quarter of 2013.