Contributions
Abstract: PB2256
Type: Publication Only
Background
Introduction of ruxolitinib in the clinical practice has changed the outcome of patients with myelofibrosis (MF), offering longer survivals and improvement of the quality of life. Nevertheless, about 50% of patients loss clinical response, and some authors ascribed this phenomenon to driver and non-driver mutations: Patel et al (Blood 2015) reported that having more than 3 mutations well correlated with shorter time to discontinuation and shorter overall survival (OS), but other investigators in the COMFORT-II trial reported that non-driver mutations did not correlate with response or survival (Guglielmelli, Blood 2014).
Aims
in order to further investigate if ruxolitinib could play any role in changing the mutational landscape in MF patients, we assessed the 3 driver and 8 non-driver mutations in 36 MF patients at diagnosis; 19 were tested also after 12 months of ruxolitinib, and compared with 4 cases receiving hydroxyurea.
Methods
JAK2, CALR, and MPL mutations were screened by qualitative/quantitative PCR. For the non-driver mutations, we designed a PCR plate with pre-spotted primers able to amplify ASXL1, EZH2, DNMT3A, IDH1, IDH2, SRSF2, TET2, TP53, for total 38 hot-spot sites (Custom qBiomarker Somatic Mutation PCR Array® - Qiagen, Italy). These genes were chosen because already included in the high molecular risk subgroup (ASXL1, EZH2, SRSF2, IDH1/2 ) or for their prognostic negative role in myeloid hematological neoplasias (DNMT3A, TP53).
Results
JAK2 was mutated in 70% of cases, CALR in 20%, whereas 10% were triple-negative. The median OS was significantly longer for primary MF (160 months) vs post-ET (80 months) or post-PV MF (35 months)(p=0.03), and for CALR- vs JAK2-mutated patients. At the last follow-up, 4 patients (11%) progressed to AML, and 12 (33%) died. The non-driver mutations were found at diagnosis in 33% of cases receiving ruxolitinib and in one/4 patients treated with hydroxyurea. Considering both driver and non-driver mutations, 24 cases (67%) were mutated, with 16 carrying one mutation, and 10 two mutations. The most frequently detected mutations belonged to the methylation pathway (DNMT3A, IDH, TET2 = 75%), followed by TP53 (17%), SRSF2 (8%), ASXL1 (8%), and EZH2 (8%). During treatment, JAK2 VAF remained stable, whereas non-driver mutations changed in 13 cases: 9 acquired a new mutation, while 4 lost the previously detected mutations. Acquisition of DNMT3A mutation was found in 5 patients, of IDH2 in one, and of TP53 in another one. None of the CALR-mutated cases carried non-driver mutations. In the 4 cases treated with hydroxyurea, during treatment one acquired TP53 and another one DNMT3A mutation. On the other hand, 4 cases lost mutations previously present at diagnosis (TP53, IDH2, ASXL1, DNMT3A) in the group of ruxolitinib, but nobody in the group of hydroxyurea. Presence/absence of non-driver mutations, their number (>1), the molecular subgroup (methylation, splicing, chromatin) did not significantly condition OS.
Conclusion
In this work, even if on a small series of patients, we showed that during ruxolitinib about the half of cases develops non-driver mutations, a percentage overlapping to that observed in cases receiving hydroxyurea. Interestingly, ruxolitinib allowed disappearance of mutations in one third of cases. Acquisition of new mutations or the type of non-driver mutations did not correlate with higher rate of death or ruxolitinib failure.
Session topic: 15. Myeloproliferative neoplasms – Biology & Translational Research
Keyword(s): mutation analysis, Myelofibrosis, Ruxolitinib
Abstract: PB2256
Type: Publication Only
Background
Introduction of ruxolitinib in the clinical practice has changed the outcome of patients with myelofibrosis (MF), offering longer survivals and improvement of the quality of life. Nevertheless, about 50% of patients loss clinical response, and some authors ascribed this phenomenon to driver and non-driver mutations: Patel et al (Blood 2015) reported that having more than 3 mutations well correlated with shorter time to discontinuation and shorter overall survival (OS), but other investigators in the COMFORT-II trial reported that non-driver mutations did not correlate with response or survival (Guglielmelli, Blood 2014).
Aims
in order to further investigate if ruxolitinib could play any role in changing the mutational landscape in MF patients, we assessed the 3 driver and 8 non-driver mutations in 36 MF patients at diagnosis; 19 were tested also after 12 months of ruxolitinib, and compared with 4 cases receiving hydroxyurea.
Methods
JAK2, CALR, and MPL mutations were screened by qualitative/quantitative PCR. For the non-driver mutations, we designed a PCR plate with pre-spotted primers able to amplify ASXL1, EZH2, DNMT3A, IDH1, IDH2, SRSF2, TET2, TP53, for total 38 hot-spot sites (Custom qBiomarker Somatic Mutation PCR Array® - Qiagen, Italy). These genes were chosen because already included in the high molecular risk subgroup (ASXL1, EZH2, SRSF2, IDH1/2 ) or for their prognostic negative role in myeloid hematological neoplasias (DNMT3A, TP53).
Results
JAK2 was mutated in 70% of cases, CALR in 20%, whereas 10% were triple-negative. The median OS was significantly longer for primary MF (160 months) vs post-ET (80 months) or post-PV MF (35 months)(p=0.03), and for CALR- vs JAK2-mutated patients. At the last follow-up, 4 patients (11%) progressed to AML, and 12 (33%) died. The non-driver mutations were found at diagnosis in 33% of cases receiving ruxolitinib and in one/4 patients treated with hydroxyurea. Considering both driver and non-driver mutations, 24 cases (67%) were mutated, with 16 carrying one mutation, and 10 two mutations. The most frequently detected mutations belonged to the methylation pathway (DNMT3A, IDH, TET2 = 75%), followed by TP53 (17%), SRSF2 (8%), ASXL1 (8%), and EZH2 (8%). During treatment, JAK2 VAF remained stable, whereas non-driver mutations changed in 13 cases: 9 acquired a new mutation, while 4 lost the previously detected mutations. Acquisition of DNMT3A mutation was found in 5 patients, of IDH2 in one, and of TP53 in another one. None of the CALR-mutated cases carried non-driver mutations. In the 4 cases treated with hydroxyurea, during treatment one acquired TP53 and another one DNMT3A mutation. On the other hand, 4 cases lost mutations previously present at diagnosis (TP53, IDH2, ASXL1, DNMT3A) in the group of ruxolitinib, but nobody in the group of hydroxyurea. Presence/absence of non-driver mutations, their number (>1), the molecular subgroup (methylation, splicing, chromatin) did not significantly condition OS.
Conclusion
In this work, even if on a small series of patients, we showed that during ruxolitinib about the half of cases develops non-driver mutations, a percentage overlapping to that observed in cases receiving hydroxyurea. Interestingly, ruxolitinib allowed disappearance of mutations in one third of cases. Acquisition of new mutations or the type of non-driver mutations did not correlate with higher rate of death or ruxolitinib failure.
Session topic: 15. Myeloproliferative neoplasms – Biology & Translational Research
Keyword(s): mutation analysis, Myelofibrosis, Ruxolitinib