Clinical and hematological relevance of JAK2 V617F and CALR mutations in BCR-ABL-negative ET patients

A customized mass array panel for BCR::ABL1 tyrosine kinase domain mutation screening in chronic myeloid leukemia

Introduction

The therapeutic strategy and management of chronic myeloid leukemia (CML) have rapidly improved with the discovery of effective tyrosine kinase inhibitors (TKIs) to target BCR::ABL1 oncoprotein. However, nearly 30% of patients develop TKI resistance due to acquired mutations on the tyrosine kinase domain (TKD) of BCR::ABL1.

Methods

We customized a mass array panel initially intended to detect and monitor the mutational burden of hotspot BCR::ABL1 TKD mutations accumulated in our database, including key mutations recently recommended by European LeukemiaNet. Additionally, we extended the feasibility of using the assay panel for the molecular classification of myeloproliferative neoplasms (MPNs) by incorporating primer sets specific for analyzing JAK2 V617F, MPL 515 K/L, and CALR types 1 and 2.

Results

We found that the developed mass array panel was superior for detecting and monitoring clinically significant BCR::ABL1 TKD mutations, especially in cases with low mutational burden and harboring compound/polyclonal mutations, compared with direct sequencing. Moreover, our customized mass array panel detected common genetic alterations in MPNs, and the findings were consistent with those of other comparable assays available in our laboratory.

Conclusions

Our customized mass array panel was practicably used as a routine robust assay for screening and monitoring BCR::ABL1 TKD mutations in patients with CML undergoing TKI treatment and feasible for analyzing common genetic mutations in MPNs.

Clinical and Hematological Relevance of JAK2V617F, CALR, and MPL Mutations in Vietnamese Patients with Essential Thrombocythemia

Background:

The picture of Vietnamese patients with essential thrombocythemia (ET) remains mostly undetermined. Our study intended to determine the frequency of JAK2V617F, CALR exon 9, and MPL exon 10 mutations as well as to analyze clinical characteristics associated with different mutational status in Vietnamese ET patients.

Methods:

We explored mutations of JAK2V617F, MPL, and CALR from 395 patients using allele specific oligonucleotide – polymerase chain reaction and Sanger sequencing techniques; then, the clinical and hematological features were compared according to mutation patterns.

Results:

We found that JAK2V617F, CALR exon 9, and MPL exon 10 mutations were present in 56.2%, 27.6%, and 1% of the 395 patients with ET, respectively. Twelve different types of CALR mutation were detected in 109 patients, with the CALR type 1 mutation (c.1099_1150del; L367fs*46) was the most common, followed by CALR type 2 mutation (c.1154_1155insTTGTC; K385fs*47). The JAK2V617F-positive patients had older age, higher white blood cell counts and higher hemoglobin levels but lower platelet counts than patients with CALR mutations or patients negative for triple tests. There was no significant difference regarding sex ratio, white blood cell counts, platelet counts and hemoglobin levels among CALR mutation subtypes.

Conclusion:

we reported high frequency of JAK2V617F, CALR, and MPL mutations in Vietnamese patients with ET and underscored the importance of combined genetic tests for diagnosis and classification of ET into different subtypes.

Essential thrombocythemia during treatment of acute myeloid leukemia with JAK2 V617F mutation: A case report of a CARE-compliant article

RATIONALE

The JAK2 V617F mutation is frequently found in ET, while it is rare in de novo AML. ET has a low frequency of leukemic transformation. Both secondary AML (sAML) from ET and AML with JAK2 V617F mutation have poor prognoses. Because of the low incidence of JAK2 mutation in acute myeloid leukemia (AML), the clinical features of AML with JAK2 mutation are rarely reported so far, either transformed from essential thrombocythemia (ET) or de novo AML.

PATIENT CONCERNS

In this article, we present a pediatric AML patient with the JAK2 V617F mutation.

DIAGNOSES

A diagnosis of acute megakaryoblastic leukemia was made and sAML was ruled out.

INTERVENTIONS

The patient underwent chemotherapy.

OUTCOMES

In the first two complete remission periods, we found significantly increased numbers of platelets and bone marrow megakaryocytes, which are characteristic of ET. After the third chemotherapy phase, the disease relapsed; the platelet count was reduced and continued to decrease. When disease relapsed, her family abandoned treatment.

LESSONS

These observations of our case raise two possibilities: either transient posttreatment thrombocythemia is a feature of AML with JAK2 V617F mutation, or this was a case of secondary AML. Additional information is required to reach better conclusions on the connection between AML and JAK2 mutations.

Rapid detection of CALR type 1 and type 2 mutations using PNA-LNA clamping loop-mediated isothermal amplification on a CD-like microfluidic chip

Bleeding and thrombosis represent common complications in myeloproliferative neoplasms (MPN) and significantly contribute to morbidity and mortality. Molecular markers, including CALR mutations, were considered not only as diagnostic markers, but also as risk factors for bleeding and thrombosis associated with MPN, especially for patients in remote primary hospitals. We sought to develop an easy-to-use assay for the rapid detection of CALR type 1 (CALR-1) and type 2 (CALR-2) mutations in Philadelphia chromosome-negative MPN patients. Peptide nucleic acid-locked nucleic acid (PNA-LNA) clamping loop-mediated isothermal amplification (LAMP) assays were established, which were integrated into a centrifugal compact disc (CD) microfluidic platform. A total of 158 clinical blood samples were tested simultaneously by this microfluidic platform and an in-house real time PCR assay. The detection performance of the LAMP arrays was validated and conflicting results were identified by Sanger sequencing. The results suggested that the LAMP methods we developed exhibited good sensitivity, specificity, and precision. By real time fluorescence assay the detection limit for CALR-1 and CALR-2 mutations could reach as low as 1% and 0.5% respectively, and 10% and 5% respectively by visual method. There were no nonspecific background amplifications among different detection systems. For the CALR-1 and CALR-2 LAMP detection systems, intra-batch CV values of 1% mutated plasmid were 10.56% and 10.51% respectively, and the inter-batch CV values were 19.55% and 18.39%, respectively. The products were all analyzed by melting curve analysis and electrophoresis followed by Sanger sequencing analysis, which were consistent with the database sequences. The microfluidic platform could complete rapid detection of CALR-1/2 mutations within 60 min. The results of clinical samples detected by our CD-like microfluidic chipLAMP assay and rtPCR assay suggested that 133 samples were CALR wild type, 15 were CALR-1 mutation type, and 9 were CALR-2 mutation type. The correlation coefficient value (Kendall's tau_b) of the two assays was 0.99. Interestingly, by the newly established detection platform, we were surprised to find that one patient of Chinese origin harbored both CALR-1 and CALR-2 mutations. This result was verified by Sanger sequencing analysis. The LAMP detection systems developed herein displayed good sensitivity, specificity, and stability. Additionally, the detection results could be directly judged by color changes of the reaction systems without any auxiliary equipment. Thus, the platform we developed has the potential of being widely used in remote and economically undeveloped areas in the future.