Contributions
Abstract: PB2032
Type: Publication Only
Background
The JAK2V617F is a main molecular marker in myeloproliferative neoplasms (MPN) and is harbored in about 50-60% of essential thrombocythemia (ET) and primary myelofibrosis (PMF). Recently, CALR mutation was described in ET and PMF JAK2V617F negative patients. There are two main variants of CALR mutation: type 1 (a 52-bp deletion) and type 2 (a 5-bp insertion).
Aims
To compare clinical and analytical data of ET and PMF patients with CALR type-1 vs CALR type-2 mutation.
Methods
We performed a single center study on 471 patients: 87 PMF and 384 ET. The JAK2V617F mutation was analyzed in DNA from peripheral blood leukocytes by PCR ARMS method. In all JAK2V617F negative patients detection of CALR mutation was performed by fragment length analysis and the results were confirmed by sequencing. Statistical data analysis was performed using Statistica 12.5 software for Windows.
Results
From 384 ET patients 254 were JAK2V617F positive (66%), 80 were CALR positive (21%) and 51 were JAK2V617F and CALR negative (13%). From CALR positive patients: 36 (51%) had type-1, 34 (45%) type-2 mutation, and 10 (12%) type-3 mutation. From 87 PMF patients 56 were JAK2V617F positive (64%), 18 were CALR positive (21%) and 13 (15%) were JAK2V617F and CALR negative. From CALR positive groups: 13 (72%) had type-1 and 5 (28%) had type-2 mutation. Compared with ET carrying JAK2V617F mutation, patients ET CALR positive (type-1 plus type-2) had lower hemoglobin (13.3 vs 14.5 g/dl, p<0.001) and leukocyte (8.2 vs 9.7 G/L, p<0.001), higher platelet counts (1067 vs 800 G/L, p<0.001) but with no significant differences in frequency of thrombosis. In ET, CALR mutation was associated with increased odds of myelofibrotic transformation (odds ratio [OR] = 2.61; 95% CI: 1.28 - 5.34; p=0.009) comparing with JAK2V617F positive patients. Patients ET CALR type-1 had higher leukocyte counts than ET CALR type-2 mutation (9.6 vs 7.3 G/L, p= 0.008), but we did not find significant differences in hemoglobin, platelet counts, frequency of thrombosis or myelofibrotic transformation. Within PMF, no significant differences were observed. Moreover in PMF, there was no significant differences between the JAK2V617F, CALR type-1 and type-2 mutation status respect to the International Prognostic Score System (IPSS).
Conclusion
1. In our population, the frequency of JAK2 and CALR mutation was similar to previously described. 2. Compared patients with ET JAK2V617F positive, ET CALR positive (type-1 plus type-2) had higher platelet count but no higher frequency of thrombosis was observed. 3. Myelofibrotic transformation was more frequent in ET CALR positive versus JAK2V617F positive patients. 4. ET patients CALR type-1 versus type-2 had higher leukocyte count but there were no more significant differences between these two groups. 5. There were no significant differences within PMF group (to small number of patients). 6. In PMF patients, there was no relations between IPSS and mutational status (JAK2V617F, CALR type-1 and type-2).
Session topic: 16. Myeloproliferative neoplasms - Clinical
Keyword(s): Myelofibrosis, Mutation status, Essential Thrombocytemia, Clinical outcome
Abstract: PB2032
Type: Publication Only
Background
The JAK2V617F is a main molecular marker in myeloproliferative neoplasms (MPN) and is harbored in about 50-60% of essential thrombocythemia (ET) and primary myelofibrosis (PMF). Recently, CALR mutation was described in ET and PMF JAK2V617F negative patients. There are two main variants of CALR mutation: type 1 (a 52-bp deletion) and type 2 (a 5-bp insertion).
Aims
To compare clinical and analytical data of ET and PMF patients with CALR type-1 vs CALR type-2 mutation.
Methods
We performed a single center study on 471 patients: 87 PMF and 384 ET. The JAK2V617F mutation was analyzed in DNA from peripheral blood leukocytes by PCR ARMS method. In all JAK2V617F negative patients detection of CALR mutation was performed by fragment length analysis and the results were confirmed by sequencing. Statistical data analysis was performed using Statistica 12.5 software for Windows.
Results
From 384 ET patients 254 were JAK2V617F positive (66%), 80 were CALR positive (21%) and 51 were JAK2V617F and CALR negative (13%). From CALR positive patients: 36 (51%) had type-1, 34 (45%) type-2 mutation, and 10 (12%) type-3 mutation. From 87 PMF patients 56 were JAK2V617F positive (64%), 18 were CALR positive (21%) and 13 (15%) were JAK2V617F and CALR negative. From CALR positive groups: 13 (72%) had type-1 and 5 (28%) had type-2 mutation. Compared with ET carrying JAK2V617F mutation, patients ET CALR positive (type-1 plus type-2) had lower hemoglobin (13.3 vs 14.5 g/dl, p<0.001) and leukocyte (8.2 vs 9.7 G/L, p<0.001), higher platelet counts (1067 vs 800 G/L, p<0.001) but with no significant differences in frequency of thrombosis. In ET, CALR mutation was associated with increased odds of myelofibrotic transformation (odds ratio [OR] = 2.61; 95% CI: 1.28 - 5.34; p=0.009) comparing with JAK2V617F positive patients. Patients ET CALR type-1 had higher leukocyte counts than ET CALR type-2 mutation (9.6 vs 7.3 G/L, p= 0.008), but we did not find significant differences in hemoglobin, platelet counts, frequency of thrombosis or myelofibrotic transformation. Within PMF, no significant differences were observed. Moreover in PMF, there was no significant differences between the JAK2V617F, CALR type-1 and type-2 mutation status respect to the International Prognostic Score System (IPSS).
Conclusion
1. In our population, the frequency of JAK2 and CALR mutation was similar to previously described. 2. Compared patients with ET JAK2V617F positive, ET CALR positive (type-1 plus type-2) had higher platelet count but no higher frequency of thrombosis was observed. 3. Myelofibrotic transformation was more frequent in ET CALR positive versus JAK2V617F positive patients. 4. ET patients CALR type-1 versus type-2 had higher leukocyte count but there were no more significant differences between these two groups. 5. There were no significant differences within PMF group (to small number of patients). 6. In PMF patients, there was no relations between IPSS and mutational status (JAK2V617F, CALR type-1 and type-2).
Session topic: 16. Myeloproliferative neoplasms - Clinical
Keyword(s): Myelofibrosis, Mutation status, Essential Thrombocytemia, Clinical outcome