Table 5.

Kinetics of JAK2V617F during blast phase transition

MPN status	MPN diagnosis	Chronic phase BM blasts, %	Chronic phase JAK2V617F, %	Blast phase BM blasts, %	Blast phase JAK2V617F, %	Postblast phase JAK2V617F, %
JAK2V617F negative
UPN 2	PMF	1	0	10	0
UPN 4	PMF	1	0
UPN 15	PMF	0	0	24	0
UPN 29	PMF	8	0
UPN 34	PMF	3	0	35	0
UPN 36	PMF	14	0
UPN 64	MPN-U	6	0	35	0
UPN 72	MPN-U	2	0
JAK2V617F positive
UPN 1	PMF	0	62	30	46
UPN 3	SMF(ET)	3	35	15	12
UPN 16	PMF	10	67*	25	80*
UPN 32	PMF	3	78	20	78	59 (in CR1), 0 (after SCT)
UPN 33	PMF	8	45*	20	46	45 (in CR1), 0 (after SCT)
UPN 52	PV	1	75	64	21
UPN 54	PV	1	22	60	0
UPN 56	PV	1	100	21	43
UPN 65	MPN-U	0	11	15	69
UPN 67	MPN-U	2	13	15	0
UPN 71	SMF(ET)	1	67	38	11	6 (in CR1), NT (after SCT)
UPN 73	PMF	14	27	63	0
JAK2V617F unknown
UPN 5	PMF			71	0
UPN 7	PMF			21	0
UPN 8	PMF			32	0	0 (after SCT)
UPN 9	PMF			22	71	0 (after SCT), 65 (at relapse), NT (in CR2)
UPN 17	PMF			20	0
UPN 19	PMF			66	0
UPN 27	PMF			39	0
UPN 28	PMF			44	0*
UPN 39	PV			29	0
UPN 42	PV			66	80
UPN 50	PV			18	98
UPN 53	PV			34	33
UPN 55	PV			26	83
UPN 57	ET			89	44
UPN 59	ET			34	61
UPN 60	ET			39	0
UPN 61	ET			33	0
UPN 62	ET			54	0
UPN 63	ET			85	0
UPN 66	MPN-U			31	0
UPN 70	SMF(ET)			34	0

JAK2V617F mutant allele frequencies were available in both chronic and blast phase in 16 patients. Patients with less than 20% bone marrow (BM) blasts had the diagnosis of blast phase established on peripheral blood.

MPN indicates myeloproliferative neoplasm; MPN-U, MPN unclassifiable; PMF, primary myelofibrosis; PV, polycythemia vera; ET, essential thrombocythemia; SMF(ET), secondary myelofibrosis evolving from ET; SCT, stem cell transplantation; CR, complete remission with or without blood recovery; and NT, not tested.

^*Results were obtained from peripheral blood specimens.