Table 2.

Response criteria in Phase II trials

Study (year)	Drug	Partial response criteria	Complete response criteria	Ref.
Verstovsek et al. (2014)	ruxolitinib	Hematocrit <45% from week 4 until response (minimum of week 12)	Hematocrit <45% from week 4 until response (minimum of week 12) WBC count ≤10 × 109/l Platelet count ≤400 × 109/l Normal spleen per palpation Pruritus-free for ≥1 week	[29]
Kiladjian et al. (2008)	PEG–IFN-α2a	Hematocrit <45% in men and <42% in women with splenomegaly OR Platelet count <400 ×109/l OR ≥50% reduced phlebotomy requirement	Hematocrit <45%/<42% in men/women without phlebotomy Absence of splenomegaly WBC count <10 × 109/l Platelet count <400 × 109/l	[94]
Quintás-Cardama et al. (2009) Quintás-Cardama et al. (2013)	PEG–IFN-α2a PEG–IFN-α2a	≥50% reduction in phlebotomy requirement or spleen size	Hematocrit <45% in men and <42% in women Absence of thromboembolic events WBC count ≤10 × 109/l Platelet count ≤400 × 109/l Normalized spleen size All of the above achieved without phlebotomy, hydroxyurea, or anagrelide	[93,95]
Gisslinger et al. (2013)	PEG–IFN-α2b	Hematocrit <45% without phlebotomy OR Phlebotomy requirement reduced by ≥50%	Hematocrit <45% without phlebotomy Platelet count ≤400 × 109/l WBC count ≤10 × 109/l Normal spleen size Absence of thrombotic events	[100]
Gowin et al. (2012)† Andersen et al. (2013)† Rambaldi et al. (2010)† Finazzi et al. (2013)†	PEG–IFN-α2a vorinostat givinostat givinostat	Hematocrit <45% without phlebotomy OR Response in ≥3 of the other complete response categories	Hematocrit <45% without phlebotomy Platelet count ≤400 × 109/l WBC count ≤10 × 109/l Normal spleen size on imaging No disease-related symptoms	[96,108–110]

^†European LeukemiaNet 2009 criteria [41].

PEG-IFN: Pegylated interferon; WBC: White blood cell.