MYD88 mutations predict unfavorable prognosis in Chronic Lymphocytic Leukemia patients with mutated IGHV gene
Authors: Shu-Chao Qin, Yi Xia, Yi Miao, Hua-Yuan Zhu, Jia-Zhu Wu, Lei Fan, Jian-Yong Li, Wei Xu, Chun Qiao
Journal: Blood Cancer Journal (2017)

Chronic lymphocytic leukemia (CLL) is the most common leukemia in adults in the Western countries but is relatively rare in East Asia 1 .CLL is a disease of high heterogeneity.The clinical course ranges from indolence to rapid progression to death.Although the Rai and Binet clinical staging systems remain to be the cornerstone for CLL prognosis, the rapidly developed biological and genetic techniques enable the detection of novel prognostic factors.Mutations in myeloid differentiation primary response gene 88 (MYD88) in CLL were first reported in 2011 with a mutation frequency of 9/310 (2.9%) 2 .Subsequent studies found that MYD88 mutations exist in 2.0-4.4% Caucasian patients with CLL 3-7 .However, subjects of Asia showed a higher MYD88 mutated rate of 8% as previously reported 8 .The above MYD88 mutated cases consist mainly of a p. L265P substitution.CLL patients with MYD88 mutations were reported to be younger at diagnosis and have longer time to treatment (TTT) and overall survival (OS) than those with wild-type MYD88 9 .However, this conclusion was controversial 10 .Initial studies indicated that most MYD88-mutated patients belonged to the IGHV-mutated group 5,9,11 , which is generally accepted as a molecular sign of favorable prognosis.These studies could be more convincing if taking IGHV mutation status and MYD88 mutations together into prognostic consideration 10 .In the current study, we analyzed MYD88 mutations exclusively in the IGHV-mutated CLL cases to explore its prognostic value.Two hundred and eighty-four patients with previously untreated CLL at the First Affiliated Hospital of Nanjing Medical University between January 2000 and June 2016 were retrospectively enrolled.All cases were reviewed to confirm the diagnosis according to the 2008 International Workshop in CLL-National Cancer Institute (IWCLL-NCI) 12 .Clinical and biological parameters including absolute lymphocyte count, hemoglobin, platelet, cytogenetic abnormalities, mutation status of TP53, IGHV, NOTCH1 as well as surface markers of CLL cells were assessed at first presence at our center.The study was approved by the Ethics Committee of the First Affiliated Hospital of Nanjing Medical University with a reference number as 2014-SR-204.Informed consents were provided according to the Declaration of Helsinki.Mononuclear cells from 281 peripheral blood samples and three bone marrow samples of untreated CLL patients were used for AS-PCR assay.Genomic DNA was extracted using the QIAamp DNA Blood Kits (Qiagen, Düsseldorf, Germany) according to the manufacturer's recommendation.Two different forward primers (FW5′-GTGCCCATCAGAAGCGCCT-3′ and FM5′-GTGCCCATCAGAAGCGCCC-3′) and one reverse primer (5′-AGGAGGCAGGGCAGAAGTA-3′) were used to amplify the wild-type allele or the MYD88 L265P mutation allele as previously reported 4 .The sensitivity of AS-PCR was 0.625% in the present study.The Sanger sequencing was performed to confirm the AS-PCR assay and to detect MYD88 mutations other than L265P.Exon 3-5 was amplified by Sanger sequencing with a forward primer (5′-AGCGACATCCAGTTTGTGC-3′) and a