Study of Efficacy and Safety in Polycythemia Vera Subjects Who Are Resistant to or Intolerant of Hydroxyurea: JAK Inhibitor INC424 (INCB018424) Tablets Versus Best Available Care: (The RESPONSE Trial)

Primary response was defined as having achieved hematocrit control (the absence of phlebotomy eligibility beginning at the Week 8 visit and continuing through Week 32) and Spleen Volume Reduction (a greater than or equal to 35% reduction from baseline in spleen volume at Week 32).

Durable Primary Response was defined as any participant who achieved the primary outcome measure and who maintained their response up to 48 weeks after randomization.

Complete Hematological Remission at Week 32 was defined as any participant who achieved hematocrit control with a platelet count less than or equal to 400 X 10^9/L and a white blood cell count less than or equal to 10 X 10^9/L.

Durable Complete Hematological Remission was defined as any participant who achieved Complete Hematological Remission at Week 32 and maintained their response up to 48 weeks after randomization.

Durable Hematocrit Control was defined as any participant who achieved phlebotomy eligibility independence from Week 8 to Week 32 and maintained hematocrit control up to 48 weeks after randomization.

Durable Spleen Volume Reduction was defined as a participant who achieved at least 35% reduction from baseline in spleen volume at Week 32 and maintained that response 48 weeks after randomization.

Duration of the primary response is defined as the time from the first occurrence when both components of the primary endpoint are met until the date of the first documented disease progression (end of response).

Kaplan-Meier estimates are provided for duration of primary response.

Overall Clinicohematologic Response is defined as any participant who achieved a complete or partial clinicohematologic response per the European LeukemiaNet modified criteria for response in polycythemia vera (PV). A Complete Response (CR) is defined as: hematocrit control, spleen volume reduction at least 35% from baseline, platelet count less than or equal to 400 x 10(9)/L, and white blood cell count less than or equal to 10 x 10(9)/L. A Partial Response (PR) is defined as hematocrit control or response in all 3 of the other criteria.

Durable Complete or Partial Clinicohematologic Response was defined as any participant who achieved complete or partial clinicohematologic response per the European LeukemiaNet modified criteria for response in polycythemia vera at Week 32 and maintained that response 48 weeks after randomization.

Duration of the complete hematological remission is defined as the time from the first occurrence of complete hematological remission until the date of the first documented progression (end of response).

Kaplan-Meier estimates are provided for duration of complete hematological remission.

Duration of the absence of phlebotomy eligibility is defined as the time from the first occurrence of absence of phlebotomy eligibility until the date of the first documented progression.

Duration of spleen volume reduction is defined as the time from the first occurrence of a >=35% reduction from baseline in spleen volume until the date of the first documented progression.

Duration of the overall clinicohematologic response was defined as the time from the first occurrence of complete response (CR) or partial response (PR) until the date of the first documented disease progression.