Cell of origin (COO), BCL2/MYC status and IPI define a group of patients with Diffuse Large B-cell Lymphoma (DLBCL) with poor prognosis in a real-world clinical setting

Clinical relevance of MYC/BCL2 expression and cell of origin in patients with diffuse large b-cell lymphoma treated with autologous transplant

Dual expression of MYC and BCL2 proteins (double-expressor lymphoma [DEL]) as well as cell of origin (COO) are important prognostic factors in patients with diffuse large B-cell lymphoma (DLBCL) after conventional chemotherapy. We studied the prognostic impact of DEL and COO in patients with relapsed DLBCL treated with autologous stem cell transplant (ASCT). Three-hundred and three patients with stored tissue samples were identified. Classification was successful in 267 patients: 161 (60%) were DEL/non-double hit (DHL), 98 (37%) were non-DEL/non-DHL, and 8 (3%) were DEL/DHL. Compared to non-DEL/non-DHL, DEL/DHL had worse overall survival while DEL/non-DHL did not significantly differ in overall survival. On multivariable analysis, DEL/DHL, age >60 years, and >2 prior therapies, but not COO, were important prognostic factors for overall survival. When we explored the interaction of COO and BCL2 expression, patients with germinal center B-cell (GCB)/BCL2 (+) had inferior progression-free survival (PFS) compared to GCB/BCL2 (-) patients (HR, 4.97; P = 0.027). We conclude that the DEL/non-DHL and non-DEL/non-DHL subtypes of DLBCL have similar survival after ASCT. The negative impact of GCB/BCL2 (+) on PFS warrants future trials targeting BCL2 after ASCT. The inferior outcomes in DEL/DHL need to be verified in a larger number of patients.

Clinico-Pathological, Cytogenetic and Molecular Profiles of Primary Cutaneous Diffuse Large B-Cell Lymphomas

We analyzed the clinico-pathological, cytogenetic and molecular features of 18 Primary Cutaneous Diffuse Large B-Cell Lymphoma (PCDLBCL), and 15 DLBCL secondarily localized to the skin (SCDLBCL), highlighting biologic similarities and differences between the two groups. PCDLBCL were sub classified after histopathological review as PCDLBCL-Leg type (PCDLBCL-LT, 10 cases) and the PCDLBCL-not otherwise specified (PCDLBCL, NOS, 8 cases). Immunohistochemistry for Hans' algorithm markers, BCL2, and MYC was performed. The molecular study included the determination of the cell of origin (COO) by Lymph2Cx assay on Nano string platform, FISH analysis of IgH, BCL2, BCL6, and MYC genes, as well as the mutation analysis of MYD88 gene. At immunohistochemistry, BCL2 and MYC hyper expression was more frequent in LT than in NOS cases and, according to Hans' algorithm, PCDLBCL LT were mostly of the non-GC type (8/10), whereas in PCDLBCL NOS the GC type prevailed (6/8). The determination of COO using Lymph2Cx supported and further confirmed these results. At FISH analysis, all but one LT cases versus 5 out of 8 PCDLBCL NOS showed at least one gene rearrangement among IgH, BCL2, MYC or BCL6. In addition, MYD88 mutations were more frequently present in LT than in NOS subtypes. Interestingly, MYD88- mutated patients were older, with a non-GC phenotype and had worse OS, compared to MYD88 WT cases. Overall, SCDLBCL did not show, at the genetic and expression level, different profiles than PCDLBCL, even if they bear a significantly worse prognosis. At survival analysis, the most important prognostic factors in PCDLBCL patients were age and MYD88 mutation, whereas relapse and high Ki67 expression were relevant in SCDLBCL patients. Our study comprehensively analyzed the clinico-pathological and molecular features of PCDLBCL LT, PCDLBCL-NOS, and SCDLBCL, underlining the differnces among them and the importance of properly identifying these entities at the time of diagnosis.

[Clinical features and prognosis of 166 cases of MYC/BCL2 double-expression diffuse large B-cell lymphoma]

Objective: To investigate the clinical features and prognosis of MYC/BCL2 double-expression diffuse large B-cell lymphoma (DEL) . Methods: The clinical data, including clinical characteristics, survival, and prognostic factors, of 166 patients with DEL treated at Peking University Third Hospital from January 2016 to December 2020 were retrospectively analyzed. Results: A total of 410 patients with diffuse large B-cell lymphoma were collected, including 166 cases (40.5%) of DEL. There were 82 males and 84 females with a median age of 63.5 (21-95) years at diagnosis. A total of 110 patients (66.3%) were aged over 60 years at initial diagnosis, 106 patients (106/163, 65.0%) had elevated lactate dehydrogenase (LDH) at diagnosis, 74 patients (74/160, 46.2%) had β(2) microglobulin level over 3 mg/L at diagnosis, and 107 patients (107/163, 65.6%) had≥2 extranodal involvement. Sixty-five patients (65/166, 39.2%) had B symptoms, 131 patients (131/165, 79.4%) had stage Ⅲ and Ⅳ disease at initial diagnosis, 41 patients (41/161, 25.5%) had an International Prognostic Index (IPI) score of 0-2 at initial diagnosis, and 38 patients (38/161, 23.6%) had an IPI score of 3 at initial diagnosis. Eighty-two patients (82/161, 50.9%) had an IPI score of 4-5 at initial diagnosis. Nine (9/56, 16.1%) patients with DEL had MYD88 and CD79B mutations. Univariate analysis showed that age over 60 years (P=0.004) , increased β(2) microglobulin level (P=0.002) , and high IPI score (P=0.003) were associated with poor overall survival (OS) . Increased β(2) microglobulin level (P=0.031) , LDH level (P=0.017) , stage Ⅲ-Ⅳ (P=0.001) , high IPI score (P=0.013) , immunohistochemical p53 mutation (P=0.049) , and PIM1 mutation (P=0.039) were associated with poor progression-free survival (PFS) . Multivariate analysis showed that IPI score of 4-5 was an independent risk factor for the prognosis of DEL (HR=2.622, 95% CI 1.398-4.917, P=0.003) . Survival analysis showed that there was a significant difference in the PFS between patients with DEL and those without DEL (65.6% vs 75.1%, P=0.002) . However, there was no significant difference in the OS (81.8% vs 83.6%, P=0.226) . In patients with DEL, the overall response rate of R-EPOCH regimen was higher than that of RCHOP or RCHOP-like regimen (81.5% vs 63.4%, P=0.004) . Conclusion: DEL is a group of aggressive lymphomas with relatively poor PFS. The R-EPOCH regimen may improve the overall prognosis of patients.

Digital Droplet PCR in Hematologic Malignancies: A New Useful Molecular Tool

Digital droplet PCR (ddPCR) is a recent version of quantitative PCR (QT-PCR), useful for measuring gene expression, doing clonality assays and detecting hot spot mutations. In respect of QT-PCR, ddPCR is more sensitive, does not need any reference curve and can quantify one quarter of samples already defined as "positive but not quantifiable". In the IgH and TCR clonality assessment, ddPCR recapitulates the allele-specific oligonucleotide PCR (ASO-PCR), being not adapt for detecting clonal evolution, that, on the contrary, does not represent a pitfall for the next generation sequencing (NGS) technique. Differently from NGS, ddPCR is not able to sequence the whole gene, but it is useful, cheaper, and less time-consuming when hot spot mutations are the targets, such as occurs with IDH1, IDH2, NPM1 in acute leukemias or T315I mutation in Philadelphia-positive leukemias or JAK2 in chronic myeloproliferative neoplasms. Further versions of ddPCR, that combine different primers/probes fluorescences and concentrations, allow measuring up to four targets in the same PCR reaction, sparing material, time, and money. ddPCR is also useful for quantitating BCR-ABL1 fusion gene, WT1 expression, donor chimerism, and minimal residual disease, so helping physicians to realize that "patient-tailored therapy" that is the aim of the modern hematology.