Contributions
Abstract: PB2047
Type: Publication Only
Background
In 2013, in the majority of JAK2V617F negative patients with essential thrombocytosis (ET) and primary myelofibrosis (PMF) have been identified mutations in the 9 exon of CALR gene. Described more than 30 different mutations, subdivided into two subtypes: deletions (type I) and insertions (type II). There are data on the phenotypic effects, depending on the version of CALR mutations. However, the prognostic significance of mutations CALR is still insufficiently clear.
Aims
To assess the impact of the type I and type II mutations of CALR on the clinical and laboratory features of ET and PM.
Methods
A multicenter retrospective study was carried out. Samples of peripheral venous blood was obtained from 149 patients with ET (n = 76) and PMF (n = 73). Patients that were negative for JAK2V617F and MPL515L/K mutations were studied for CALR mutations presence as described in original paper (Т.Klampf, 2013). CALR Mutations were detected in 34 patients with ET (10 - men, 24 - women) and 25 patients with PMF (13 - men, 12 - women). Statistical data processing was carried out in the program STATISTICA for Windows 6.0.
Results
The frequency of mutations CALR was comparable in patients with ET and PMF (44.7% and 35.6%). Mutations of type II is 2 times more common in ET than with the TFM: 17.1% vs. 9.6% (p = 0.178). Mutations of type I detected in 21 cases in ET, in 18 cases - in PMF, type II in 13 cases - in ET and 7 - in PMF. The median of follow-up period of patients with ET with type I mutation was 36 months (3-87), with type II - 22 months (2-90). In PMF, the median of follow-up in the group with type I mutation was 46 months (3- 133), type II - 77 months (4-115). Hematological parameters in patients with ET showed higher levels of WBC in patients with type I mutation (p = 0.043), the level of Hb in this variant was lower (p = 0.009). In PMF levels of Hb were similar in the studied groups. Type of mutations had no significant effect on the number of WBC in patients with PMF. However, PLT was higher in PMF patients with type II mutations of CALR (p = 0.014). Spleen size in ET patients on the time of the diagnosis date was slightly different: in type I - 106,5mm, type II - 119,6mm (p = 0.076). The type of mutation in our study had no effect on the stratification according to the IPSET. Also there were no significant differences in assessing of the effect of therapy. Spleen size on the time of the diagnosis date in PMF patients with type I mutation were slightly larger (180,9mm vs 169,9mm). Revealed more pronounced fibrotic changes of the bone marrow (BM) in patients with type I CALR mutations (p <0,005). CALR mutation type had no influence on the distribution of patients with PMF, depending on the risk groups on the scale of IPSS and DIPSS.
Conclusion
The effect of the type of CALR mutation on the clinical and laboratory features of the ET and PMF has found. Type of CALR mutations in our study had no effect on the number of PLT in ET, but have a value for this index in PMF. Type I mutations in ET accompanied higher WBC level and a lower level of Hb. The published studies have not shown the influence of the type of mutation in the Hb level and the number of WBC in ET. An important observation was the detection of the effect of type I mutations on development fibrotic changes of BM in PMF. Our data are consistent with previously published studies that showed no effect on the stratification of patients according to the scale on the IPSS.
Session topic: 16. Myeloproliferative neoplasms - Clinical
Keyword(s): Myeloproliferative disorder, Myelofibrosis, Mutation status, Essential Thrombocytemia
Abstract: PB2047
Type: Publication Only
Background
In 2013, in the majority of JAK2V617F negative patients with essential thrombocytosis (ET) and primary myelofibrosis (PMF) have been identified mutations in the 9 exon of CALR gene. Described more than 30 different mutations, subdivided into two subtypes: deletions (type I) and insertions (type II). There are data on the phenotypic effects, depending on the version of CALR mutations. However, the prognostic significance of mutations CALR is still insufficiently clear.
Aims
To assess the impact of the type I and type II mutations of CALR on the clinical and laboratory features of ET and PM.
Methods
A multicenter retrospective study was carried out. Samples of peripheral venous blood was obtained from 149 patients with ET (n = 76) and PMF (n = 73). Patients that were negative for JAK2V617F and MPL515L/K mutations were studied for CALR mutations presence as described in original paper (Т.Klampf, 2013). CALR Mutations were detected in 34 patients with ET (10 - men, 24 - women) and 25 patients with PMF (13 - men, 12 - women). Statistical data processing was carried out in the program STATISTICA for Windows 6.0.
Results
The frequency of mutations CALR was comparable in patients with ET and PMF (44.7% and 35.6%). Mutations of type II is 2 times more common in ET than with the TFM: 17.1% vs. 9.6% (p = 0.178). Mutations of type I detected in 21 cases in ET, in 18 cases - in PMF, type II in 13 cases - in ET and 7 - in PMF. The median of follow-up period of patients with ET with type I mutation was 36 months (3-87), with type II - 22 months (2-90). In PMF, the median of follow-up in the group with type I mutation was 46 months (3- 133), type II - 77 months (4-115). Hematological parameters in patients with ET showed higher levels of WBC in patients with type I mutation (p = 0.043), the level of Hb in this variant was lower (p = 0.009). In PMF levels of Hb were similar in the studied groups. Type of mutations had no significant effect on the number of WBC in patients with PMF. However, PLT was higher in PMF patients with type II mutations of CALR (p = 0.014). Spleen size in ET patients on the time of the diagnosis date was slightly different: in type I - 106,5mm, type II - 119,6mm (p = 0.076). The type of mutation in our study had no effect on the stratification according to the IPSET. Also there were no significant differences in assessing of the effect of therapy. Spleen size on the time of the diagnosis date in PMF patients with type I mutation were slightly larger (180,9mm vs 169,9mm). Revealed more pronounced fibrotic changes of the bone marrow (BM) in patients with type I CALR mutations (p <0,005). CALR mutation type had no influence on the distribution of patients with PMF, depending on the risk groups on the scale of IPSS and DIPSS.
Conclusion
The effect of the type of CALR mutation on the clinical and laboratory features of the ET and PMF has found. Type of CALR mutations in our study had no effect on the number of PLT in ET, but have a value for this index in PMF. Type I mutations in ET accompanied higher WBC level and a lower level of Hb. The published studies have not shown the influence of the type of mutation in the Hb level and the number of WBC in ET. An important observation was the detection of the effect of type I mutations on development fibrotic changes of BM in PMF. Our data are consistent with previously published studies that showed no effect on the stratification of patients according to the scale on the IPSS.
Session topic: 16. Myeloproliferative neoplasms - Clinical
Keyword(s): Myeloproliferative disorder, Myelofibrosis, Mutation status, Essential Thrombocytemia