Gregory Lazarian

The prognostic and predictive impact of TP53 variants in leukemia led to their inclusion in diagnostic and treatment guidelines, increasing the demand for rapid, reliable laboratory analysis, interpretation, and reporting. While most TP53 variants identified in tumor samples can be interpreted using data from large‐scale functional studies, evidence regarding the impact of in‐frame deletions and insertions not disturbing the reading frame remains limited. Consequently, the classification of somatic in‐frame variants often relies on expert judgment rather than standardized criteria. To address this gap, we collected in‐frame TP53 variants identified during routine diagnostic testing in laboratories within the TP53 Network of Education and Research Initiative on Chronic Lymphocytic Leukemia (ERIC). We analyzed 60 leukemia samples from 13 laboratories, comprising 54 distinct variants. Initial classification using existing data and interpretation guidelines assigned these variants predominantly to the category of variants of uncertain significance. Functional analyses using a yeast‐based transactivation assay, complemented by testing selected variants in the TP53 ‐knockout RPE1 cell line, showed a nonfunctional phenotype for the vast majority of in‐frame TP53 variants. This indicates that most in‐frame alterations detected in leukemia samples are functionally deleterious, as further supported by their association with second‐allele inactivation and frequent clonal expansion in relapse. With respect to variant localization, we observed that 49 variants located within the core region of the DNA‐binding domain showed complete loss of transactivation function. The five variants located downstream of codon 286 exhibited heterogeneous functional phenotypes depending on their localization and the experimental system used. In conclusion, the integration of our findings with published functional data supports the interpretation that in‐frame TP53 variants within the core DNA‐binding domain identified in tumor samples are likely pathogenic. Conversely, interpretation of less frequent in‐frame variants outside this region requires integration of multiple evidence, including functional studies, published literature, and curated variant databases. © 2026 The Author(s). The Journal of Pathology published by John Wiley & Sons Ltd on behalf of The Pathological Society of Great Britain and Ireland.

Background and Clinical Significance: Plasmablastic lymphoma (PBL) is a rare and highly aggressive B-cell neoplasm most often associated with immunodeficiency. Transformation of chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL/SLL) into PBL is exceptionally uncommon, particularly in immunocompetent individuals. This paper describes a rare synchronous SLL-to-PBL transformation and summarizes current knowledge on synchronous and metachronous cases reported in the literature. Case Presentation A midle-aged immunocompetent patent presented with generalized lymphadenopathy and lumbar pain. Concurrent biopsies of an axillary lymph node and a retroperitoneal mass were obtained. Diagnostic evaluation included immunohistochemistry; fluorescent in situ hybridization (FISH); PCR-based assessment of IGH, IGK, and IGL loci; and next-generation sequencing (NGS) of IGHV to assess clonal relatedness. The patient was treated with six cycles of Dara-CHOP, followed by autologous stem cell transplantation and maintenance therapy with daratumumab and ibrutinib. The axillary node showed SLL (CD20+, CD5+, CD23+), while the retroperitoneal mass demonstrated classic features of PBL (CD138+, MUM1+, MYC+, Ki-67 ~100%, CD20−). FISH detected MYC rearrangement in the PBL component. PCR and NGS confirmed identical IGHV1-69 rearrangements, establishing clonal relatedness and Richter transformation. A review of published cases shows that both synchronous and metachronous CLL/SLL-to-PBL transformations are exceedingly rare. The patient achieved partial metabolic remission after treatment and remains in sustained metabolic response 24 months after diagnosis. Conclusions: This case highlights a rare example of synchronous CLL/SLL-to-PBL transformation in an immunocompetent patient. Integration of detailed molecular diagnostics enabled early recognition and guided a personalized treatment approach incorporating CD38-targeted therapy and BTK inhibition, resulting in an excellent long-term clinical outcome.

Background: Plasmablastic lymphoma (PBL) is a rare and highly aggressive B-cell neoplasm most often associated with immunodeficiency. Transformation of chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL/SLL) into PBL is exceptionally uncommon, particularly in immunocompetent individuals. This paper describes a rare synchronous SLL-to-PBL transformation and summarizes current knowledge on synchronous and metachronous cases reported in the literature. Methods: A 46-year-old immunocompetent woman presented with generalized lymphadenopathy and lumbar pain. Concurrent biopsies of an axillary lymph node and a retroperitoneal mass were obtained. Diagnostic evaluation included immunohistochemistry, fluorescent in situ hybridization (FISH), PCR-based assessment of IGH, IGK, and IGL loci, and next-generation sequencing (NGS) of IGHV to assess clonal relatedness. The patient was treated with six cycles of Dara-CHOP, followed by autologous stem cell transplantation and maintenance therapy with daratumumab and ibrutinib. Results: The axillary node showed SLL (CD20+, CD5+, CD23+), while the retroperitoneal mass demonstrated classic features of PBL (CD138+, MUM1+, MYC+, Ki-67 ~100%, CD20–). FISH detected MYC rearrangement in the PBL component. PCR and NGS confirmed identical IGHV1-69 rearrangements, establishing clonal relatedness and Richter transformation. Review of published cases shows that both synchronous and metachronous CLL/SLL-to-PBL transformations are exceedingly rare. The patient achieved partial metabolic remission after treatment and remains in sustained metabolic response 24 months after diagnosis. Conclusions: This case highlights a rare example of synchronous CLL/SLL-to-PBL transformation in an immunocompetent patient. Integration of detailed molecular diagnostics enabled early recognition and guided a personalized treatment approach incorporating CD38-targeted therapy and BTK inhibition, resulting in an excellent long-term clinical outcome.

In chronic lymphocytic leukemia, the reliability of next‐generation sequencing (NGS) to detect TP53 variants ≤10% allelic frequency (low‐VAF) is debated. We tested the ability to detect 23 such variants in 41 different laboratories using their NGS method of choice. The sensitivity was 85.6%, 94.5%, and 94.8% at 1%, 2%, and 3% VAF cut‐off, respectively. While only one false positive (FP) result was reported at >2% VAF, it was more challenging to distinguish true variants TP53 variants had shorter TTST and OS versus wt‐TP53 patients, and the relative risk of second‐line treatment or death increased continuously with increasing VAF. Targeted therapy in ≥2 line diminished the difference in OS between patients with low‐VAF TP53 variants and wt‐TP53 patients, while patients with high‐VAF TP53 variants had inferior OS compared to wild type‐TP53 cases. Altogether, NGS‐based approaches are technically capable of detecting low‐VAF variants. No strict threshold can be suggested from a technical standpoint, laboratories reporting TP53 mutations should participate in a standardized validation set‐up. Finally, whereas low‐VAF variants affected outcomes in patients receiving chemoimmunotherapy, their impact on those treated with novel therapies remains undetermined. Our results pave the way for the harmonized and accurate TP53 assessment, which is indispensable for elucidating the role of TP53 mutations in targeted treatment.

In the microenvironment, cell interactions are established between different cell types to regulate their migration, survival and activation. β-Catenin is a multifunctional protein that stabilizes cell–cell interactions and regulates cell survival through its transcriptional activity. We used chronic lymphocytic leukemia (CLL) cells as a cellular model to study the role of β-catenin in regulating the adhesion of tumor cells to their microenvironment, which is necessary for tumor cell survival and accumulation. When co-cultured with a stromal cell line (HS-5), a fraction of the CLL cells adhere to stromal cells in a dynamic fashion regulated by the different levels of β-catenin expression. In non-adherent cells, β-catenin is stabilized in the cytosol and translocates into the nucleus, increasing the expression of cyclin D1. In adherent cells, the level of cytosolic β-catenin is low but membrane β-catenin helps to stabilize the adhesion of CLL to stromal cells. Indeed, the overexpression of β-catenin enhances the interaction of CLL with HS-5 cells, suggesting that this protein behaves as a regulator of cell adhesion to the stromal component and of the transcriptional regulation of cell survival. Inhibitors that block the stabilization of β-catenin alter this equilibrium and effectively disrupt the support that CLL cells receive from the cross-talk with the stroma.

TP53 aberrations are a major predictive factor of resistance to chemoimmunotherapy in chronic lymphocytic leukemia (CLL), and an assessment of them before each line of treatment is required for theranostic stratification. Acquisition of subclonal TP53 abnormalities underlies the evolution of CLL. To better characterize the distribution, combination, and impact of TP53 variants in CLL, 1,056 TP53 variants collected from 683 patients included in a multicenter collaborative study in France were analyzed and compared to UMD_CLL, a dataset built from published articles collectively providing 5,173 TP53 variants detected in 3,808 patients. Our analysis confirmed the presence of several CLL-specific hotspot mutations, including a two-base pair deletion in codon 209 and a missense variant at codon 234, the latter being associated with alkylating treatment. Our analysis also identified a novel CLL-specific variant in the splice acceptor signal of intron 6 leading to the use of a cryptic splice site, similarly utilized by TP53 to generate p53psi, a naturally truncated p53 isoform localized in the mitochondria. Examination of both UMD_CLL and several recently released large-scale genomic analyses of CLL patients confirmed that this splice variant is highly enriched in this disease when compared to other cancer types. Using a TP53-specific single-nucleotide polymorphism, we also confirmed that copy-neutral loss of heterozygosity is frequent in CLL. This event can lead to misinterpretation of TP53 status. Unlike other cancers, CLL displayed a high proportion of patients harboring multiple TP53 variants. Using both in silico analysis and single molecule smart sequencing, we demonstrated the coexistence of distinct subclones harboring mutations on distinct alleles. In summary, our study provides a detailed TP53 mutational architecture in CLL and gives insights into how treatments may shape the genetic landscape of CLL patients.

Boris Duchemann, Gregory Lazarian; Post–SARS-CoV-2 vaccination acute hemolysis in an older man: don’t forget to look at the blood smear, Blood, Volume 138, Issu