Allele-specific PCR is a powerful tool for the detection of the MYD88 L265P mutation in diffuse large B cell lymphoma and decalcified bone marrow samples

Cytologic and Molecular Diagnostics for Vitreoretinal Lymphoma: Current Approaches and Emerging Single-Cell Analyses

Vitreoretinal lymphoma (VRL) is a rare ocular malignancy that manifests as diffuse large B-cell lymphoma. Early and accurate diagnosis is essential to prevent mistreatment and to reduce the high morbidity and mortality associated with VRL. The disease can be diagnosed using various methods, including cytology, immunohistochemistry, cytokine analysis, flow cytometry, and molecular analysis of bulk vitreous aspirates. Despite these options, VRL diagnosis remains challenging, as samples are often confounded by low cellularity, the presence of debris and non-target immunoreactive cells, and poor cytological preservation. As such, VRL diagnostic accuracy is limited by both false-positive and false-negative outcomes. Missed or inappropriate diagnosis may cause delays in treatment, which can have life-threatening consequences for patients with VRL. In this review, we summarize current knowledge and the diagnostic modalities used for VRL diagnosis. We also highlight several emerging molecular techniques, including high-resolution single cell-based analyses, which may enable more comprehensive and precise VRL diagnoses.

MYD88 in the driver's seat of B-cell lymphomagenesis: from molecular mechanisms to clinical implications

More than 50 subtypes of B-cell non-Hodgkin lymphoma (B-NHL) are recognized in the most recent World Health Organization classification of 2016. The current treatment paradigm, however, is largely based on 'one-size-fits-all' immune-chemotherapy. Unfortunately, this therapeutic strategy is inadequate for a significant number of patients. As such, there is an indisputable need for novel, preferably targeted, therapies based on a biologically driven classification and risk stratification. Sequencing studies identified mutations in the MYD88 gene as an important oncogenic driver in B-cell lymphomas. MYD88 mutations constitutively activate NF-κB and its associated signaling pathways, thereby promoting B-cell proliferation and survival. High frequencies of the hotspot MYD88(L265P) mutation are observed in extranodal diffuse large B-cell lymphoma and Waldenström macroglobulinemia, thereby demonstrating this mutation's potential as a disease marker. In addition, the presence of mutant MYD88 predicts survival outcome in B-NHL subtypes and it provides a therapeutic target. Early clinical trials targeting MYD88 have shown encouraging results in relapsed/refractory B-NHL. Patients with these disorders can benefit from analysis for the MYD88 hotspot mutation in liquid biopsies, as a minimally invasive method to demonstrate treatment response or resistance. Given these clear clinical implications and the crucial role of MYD88 in lymphomagenesis, we expect that analysis of this gene will increasingly be used in routine clinical practice, not only as a diagnostic classifier, but also as a prognostic and therapeutic biomarker directing precision medicine. This review focuses on the pivotal mechanistic role of mutated MYD88 and its clinical implications in B-NHL.

Detection of MYD88 and CXCR4 mutations in cell-free DNA of patients with IgM monoclonal gammopathies

Liquid biopsyis being integrated into cancer diagnostics with profound therapeutic implications. However, its role in Waldenström's Macroglobulinemia (WM) and IgM monoclonal gammopathies is still unclear. In this study, we evaluated the role of peripheral blood (PB) cell-free DNA (cfDNA) in characterizing the mutational status of MYD88 and CXCR4 of patients with IgM monoclonal gammopathies. Paired bone marrow (BM) tumor DNA (tDNA) and PB cfDNA samples from 98 patients (9 MGUS, 45 with WM in remission, 44 with smoldering WM, newly diagnosed or relapsed WM) and 10 controls with non-IgM monoclonal gammopathies were analyzed. Regarding MYD88^L265P mutation, 76 patients had paired tDNA and cfDNA informative samples. Among patients with WM in remission, 65% harbored the MYD88^L265P mutation, whereas the corresponding percentage among smoldering/newly diagnosed or relapsed WM was 92%. The overall concordance rate was 94% (72/76). For CXCR4 mutations, 65 patients had paired informative tDNA and cfDNA samples. The overall concordance rate was 90% (59/65). All controls had wild-type MYD88 and CXCR4. In conclusion, PB cfDNA is a useful, minimally invasive, cost-effective, and time-effective tool for the identification of the presence of MYD88 and CXCR4 mutations in patients with IgM monoclonal gammopathies avoiding unnecessary BM assessment.

MYD88 mutation status does not impact overall survival in Waldenström macroglobulinemia

Waldenström macroglobulinemia (WM) is an immunoglobulin M-associated lymphoma, with majority of cases demonstrating MYD88 locus alteration, most commonly, MYD88^L265P . Owing to low prevalence of the wild-type (WT) MYD88 genotype in WM, clinically relevant data in this patient population are sparse, with one study showing nearly a 10-fold increased risk of mortality in this subgroup compared to patients with MYD88^L265P mutation. We studied a large cohort of patients with MYD88^L265P and MYD88^WT WM, evaluated at Mayo Clinic, Rochester, between 1995 and 2016, to specifically assess the impact of these genotypes on clinical course. Of 557 patients, MYD88^L265P mutation status, as determined by allele-specific polymerase chain reaction, was known in 219, and 174 (79%) of those exhibited MYD88^L265P , 157 of 174 patients had active disease. Of 45 (21%) patients with MYD88^WT genotype, 44 had active disease. The estimated median follow-up was 7.0 years; median overall survival was 10.2 years (95% CI: 8.4-16.5) for MYD88^L265P versus 13.9 years (95% CI: 6.4-29.3) for the MYD88^WT (P = 0.86). The time-to-next therapy from frontline treatment and the presenting features were similar in the two patient populations. For patients with smoldering WM at diagnosis, the median time-to-progression to active disease was 2.8 years (95% CI: 2.2-3.8) in the MYD88^L265P cohort and 1.9 years (95% CI: 0.7-3.1) in the MYD88^WT cohort (P = 0.21). The frequency of transformation to high-grade lymphoma, or the development of therapy-elated myelodysplastic syndrome was higher in the MYD88^WT cohort (16% versus 4% in the MYD88^L265P , P = 0.009). In conclusion, MYD88^L265P mutation does not appear to be a determinant of outcome, and its presence may not be a disease-defining feature in WM. Our findings warrant external validation, preferably through prospective studies.

High frequency and prognostic value of MYD88 L265P mutation in diffuse large B-cell lymphoma with R-CHOP treatment

The aim of this study was to analyze the prevalence and prognostic value of myeloid differentiation factor 88 (MYD88) L265P in diffuse large B-cell lymphoma (DLBCL) patients treated with rituximab plus cyclophosphamide, doxorubicin, vincristine, and prednisone (R-CHOP). We assessed the MYD88 L265P mutation using an allele-specific semi-nested polymerase chain reaction method in 53 DLBCL patients treated with R-CHOP. The MYD88 L265P mutation was detected in 16 of 53 DLBCL (30.19%) samples from patients treated with R-CHOP. Age and location were statistically significantly associated with MYD88 L265P (P=0.025, 0.033, respectively), while treatment response and tumor recurrence were not. Univariate analysis showed that B symptoms (P=0.004) and Ki-67 (P=0.03) were significantly associated with progression-free survival (PFS), while MYD88 L265P showed no significant association with overall survival and PFS. Multivariate analysis showed that B symptoms were significantly associated with PFS. Our study suggests that the prognostic value of MYD88 L265P in DLBCL patients with R-CHOP requires further research.

Clinicopathologic significance of MYD88 L265P mutation in diffuse large B-cell lymphoma: a meta-analysis

The precise clinicopathologic significance of myeloid differentiation primary response gene (MYD88) L265P mutation in diffuse large B-cell lymphomas (DLBCLs) remains elusive. To investigate the frequency and clinicopathologic significance of the MYD88 L265P mutation in DLBCLs, we conducted a meta-analysis of 40 published studies on 2736 DLBCL patients. We collected relevant published research findings identified using the PubMed and Embase databases. The effect sizes of outcome parameters were calculated using a random-effects model. In this meta-analysis, the MYD88 L265P mutation in DLBCL showed a significant difference according to tumor sites. The overall incidence of the MYD88 L265P mutation in DLBCLs, excluding the central nervous system and testicular DLBCLs, was 16.5%. Notably, the MYD88 L265P mutation rates of CNS and testicular DLBCL patients were 60% and 77%, respectively. Interestingly, the MYD88 L265P mutation was more frequently detected in activated B-cell-like (ABC) or non-germinal center B-cell-like (GCB) than GCB subtype (OR = 3.414, p < 0.001). The MYD88 L265P mutation was significantly associated with old age and poor overall survival, but not with sex and clinical stage. This pooled analysis demonstrates that the MYD88 L265P mutation is significantly associated with the tumor sites and molecular subtypes in DLBCL patients.

Detection of MYD88 L265P and WHIM-like CXCR4 mutation in patients with IgM monoclonal gammopathy related disease

A broad spectrum of diseases are associated with IgM monoclonal gammopathy, including Waldenstrom macroglobulinemia (WM), various types of B cell non-Hodgkin's lymphoma (NHL), multiple myeloma (MM), primary amyloidosis (AL), and monoclonal gammopathy of undetermined significance (MGUS); these are called IgM monoclonal gammopathy related diseases (IgM-RD). We investigated MYD88 L265P and WHIM-like CXCR4 mutations in various IgM-RD. Patients with serum immunofixation electrophoresis confirmed IgM monoclonal gammopathy who had enough material for DNA extraction and presented between January 2008 and October 2016 at Peking Union Medical College Hospital were enrolled in this cohort. We performed real-time allele-specific-polymerase chain reaction and Sanger sequencing to explore the presence of MYD88 L265P and WHIM-like CXCR4 mutations. One hundred and twelve patients (64 male and 48 female patients) were included in this retrospective study. The median age at diagnosis was 62 years (range, 30-84 years). In total, 64 patients (57.1%) carried the MYD88 L265P mutation and 14 patients (12.5%) carried the CXCR4 WHIM-like mutation. We identified the MYD88 L265P somatic variant in cases with WM (39/42), MGUS (8/18), NHL (14/41, including 4/13 diffuse large B cell lymphoma (DLBCL), 1/8 mucosa-associated lymphoid tissue, 3/6 splenic marginal zone lymphoma (SMZL), 1/4 chronic lymphocytic leukemia, 2/3 nodal marginal zone lymphoma (NMZL), 1/2 mantle cell lymphoma, 1 Burkitt lymphoma, and 1 B cell NHL that could not be classified), primary AL (2/2), and IgM-PN (1/1). The mutation was absent in five patients with Cryoglobulinemia, two with primary cold agglutinin disease and one with MM. The CXCR4 WHIM-like mutation was present in 10/42 patients with WM, 3/41 with NHL (1 DLBCL, 1 SMZL, and 1 NMZL), and 1/18 patients with IgM MGUS. Among the patients with NHL, those with the mutated MYD88 L265P genotype were younger and had lower level of IgG and IgA than the patients with the wild-type genotype. Patients with the mutated MYD88 L265P genotype with WM and MZL were compared. More male patients, higher levels of IgM and lower levels of LDH were found in the WM group. There was no significant difference in overall survival between the two groups. We present a study of the prevalence of the MYD88 L265P mutation and CXCR4 WHIM-like mutation in IgM RD. The MYD88 L265P mutation may play a key role in the pathogenesis of IgM monoclonal gammopathies. It would be interesting in the future to use MYD88 mutation status to differentiate among diseases.

Detection of MYD88 L265P in patients with lymphoplasmacytic lymphoma/Waldenstrom macroglobulinemia and other B-cell non-Hodgkin lymphomas

Background

Recent studies have identified a high prevalence of the MYD88 L265P mutation in lymphoplasmacytic lymphoma (LPL)/Waldenstrom macroglobulinemia (WM) cases, whereas low frequencies have been observed in other B cell non-Hodgkin lymphomas (NHLs).

Methods

We evaluated the sensitivity of the mutant enrichment 3'-modified oligonucleotide (MEMO)-PCR technique, a new detection method. We examined the MYD88 L265P mutation in a series of Korean patients with LPL/WM and other B cell NHLs in bone marrow aspirates, using the MEMO-PCR technique.

Results

The sensitivity of MEMO-PCR was estimated to be approximately 10-16.7%. MYD88 L265P was detected in 21 of 28 LPL cases (75%) and only three of 69 B cell NHL cases (4.3%).

Conclusion

Although MEMO-PCR had relatively low sensitivity, we confirmed the high prevalence of the MYD88 L265P mutation in Korean LPL patients. Our study suggests the diagnostic value of MYD88 L265P for differentiating B-cell NHLs.