Ruxolitinib In Polycythemia Vera: Follow-Up From The Response Trial.

7087 Background: The RESPONSE trial is a multicenter, open-label phase 3 study evaluating the efficacy and safety of ruxolitinib (Rux) compared with best available therapy (BAT) in patients (pts) with polycythemia vera resistant to or intolerant of hydroxyurea. Results from the primary analysis, 48 wks from last pt first treatment (LPFT), were published (Vannucchi, NEJM 2015). Methods: This was a second preplanned analysis 80 wks after LPFT. The primary response was defined as achieving both hematocrit (HCT) control without phlebotomy (PBT) through wk 32 and a ≥ 35% reduction in spleen volume (SV) by imaging at wk 32. Durability of the primary response, HCT control, spleen volume reduction, and complete hematologic remission (CHR), as well as long-term safety, were evaluated. Results: At data cutoff, 91 (82.7%) pts randomized to Rux (Rux arm) were receiving treatment (median exposure, 111 wks), compared to 93 (84.5%) at the wk 48 analysis (median exposure, 81 wks). No pts remained on BAT, compared to 3 pt...