SAR302503 Meets Primary Endpoint in JAKARTA Trial

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Debasish Roychowdhury, MD

Debasish Roychowdhury, MD

The phase III JAKARTA trial of SAR302503 for myelofibrosis met its primary endpoint in both dose groups, as reported by Sanofi, the drug’s manufacturer. SAR302503 is a novel JAK2 inhibitor; dysregulated JAK/STAT signaling is associated with the development of myelofibrosis and other related myeloproliferative neoplasms.

"Patients with myelofibrosis in advanced stages are desperately ill and in need of treatments that will improve their outcomes," said Debasish Roychowdhury, MD, Senior Vice President and Head, Sanofi Oncology, in a statement. Sanofi now plans to move ahead with regulatory filings, Roychowdhury said.

Mechanism of Action: SAR302503

Tal Zaks, MD, PhD, vice president and head of development at Sanofi Oncology, explains the mechanism of action of SAR302503

The double-blind, randomized JAKARTA study analyzed once-daily oral SAR302503 or placebo in 289 patients with intermediate-2 or high-risk primary myelofibrosis, post-polycythemia vera myelofibrosis, or post-essential thrombocythemia myelofibrosis. Eligible patients with platelet counts of at least 50,000/µl were randomized to receive 400mg or 500 mgof SAR302503, or placebo for 24 weeks (six cycles). The primary endpoint was the proportion of patients achieving at least a 35% reduction of spleen volume. Secondary endpoints included assessment of associated symptoms as measured by total symptom score using the Myelofibrosis Symptom Assessment Form (MF-SAF) diary.

Consistent with data reported in previous trials, the most common adverse events were anemia, diarrhea, nausea and vomiting. Full results of the JAKARTA study will be presented at an upcoming medical congress, according to a statement from Sanofi.

In a phase II trial reported in December 2012, SAR302503 also met its primary endpoint, demonstrating a 42% mean percentage reduction to spleen volume versus baseline. A total of 63.6% of patients achieved at least a 35% reduction.