MYD88L265P augments proximal B-cell receptor signaling in large B-cell lymphomas via an interaction with DOCK8

CD5 and p53 immunohistochemistry: valuable prediction method in molecular typing of CD5-positive diffuse large B-cell lymphoma

BACKGROUND

CD5 positive diffuse large B-cell lymphoma (DLBCL) has unique clinical and pathological characteristics.

METHODS

We analyzed 25 cases of CD5-positive DLBCL, focusing on their clinical, morphological, immunohistochemical and genetic features.

RESULTS

Among the 13 females and 12 males, 14 were over 60 years (14/25, 56%). A majority of them presented in stage IV (15/21, 71.43%), primarily with extranodal lesions (14/25, 56%). The positive expression rates of CD20, CD10, BCL6, MUM1, MYC, and BCL2 were 100% (25/25), 40% (10/25), 84% (21/25), 100% (25/25), 87.5% (21/24) and 100% (25/25), respectively. Twenty-one cases (87.5%, 21/24) were MYC/BCL2 double-expressing. More than half of the cases were non-germinal center origin (15/25, 60%). The accuracy of p53 in predicting TP53 mutation was 95.65% (22/23). Genetic subtypes were MCD (13/25, 52%), TP53Mut (7/25, 28%), EZB (1/25, 4%) and Other subtype (4/25, 16%). Among CD5 strong positive cases, 7 of the p53 wild-pattern cases were MCD subtype (7/8, 87.5%) and 6 of the p53 mutant-pattern cases were classified as TP53Mut subtype (6/7, 85.71%). In the CD5 weak-moderate positive group, one p53 mutant-pattern case was TP53Mut subtype (1/2, 50%), 4 of the wild-pattern cases were Other subtype (4/6, 66.67%).

CONCLUSIONS

For CD5 strong positive cases, a wild pattern of p53 likely indicates MCD subtype, while a mutant p53 pattern may suggest TP53Mut subtype. CD5 and p53 may potentially offer initial molecular subtyping for CD5-positive DLBCLs. We suggest incorporating these two markers into the routine pathological diagnosis of DLBCL to assist in guiding preliminary classification and influencing treatment decisions.

Characterizing the Mutational Landscape of Diffuse Large B-Cell Lymphoma in a Prospective Cohort of Mexican Patients

Diffuse large B-cell lymphoma (DLBCL) is the most common B-cell malignancy worldwide. Molecular classifications have tried to improve cure rates. We prospectively examined and correlated the mutational landscape with the clinical features and outcomes of 185 Mexican patients (median age 59.3 years, 50% women) with newly diagnosed DLBCL. A customized panel of 79 genes was designed, based on previous international series. Most patients had ECOG performance status (PS) < 2 (69.2%), advanced-stage disease (72.4%), germinal-center phenotype (68.1%), and double-hit lymphomas (14.1%). One hundred and ten (59.5%) patients had at least one gene with driver mutations. The most common mutated genes were as follows: TP53, EZH2, CREBBP, NOTCH1, and KMT2D. The median follow-up was 42 months, and the 5-year relapse-free survival (RFS) and overall survival (OS) rates were 70% and 72%, respectively. In the multivariate analysis, both age > 50 years and ECOG PS > 2 were significantly associated with a worse OS. Our investigation did not reveal any discernible correlation between the presence of a specific mutation and survival. In conclusion, using a customized panel, we characterized the mutational landscape of a large cohort of Mexican DLBCL patients. These results need to be confirmed in further studies.

Sending positive signals and good (calcium) vibes

In this issue of JEM, Yada et al. (https://doi.org/10.1084/jem.20222178) demonstrate that effective antibody affinity selection in germinal centers relies on the store-operated calcium entry (SOCE) component of the B cell receptor (BCR) signaling network. Therefore, active BCR signaling is as relevant to positive selection as the function of BCRs as endocytic receptors, answering a question that had puzzled experts for a while. These findings transform our understanding of the mechanisms supporting adaptive immune responses (to vaccines, for example) and have important implications for interpreting the genomics and pathogenesis of germinal center-derived B cell lymphomas.