Genomic features of newly diagnosed large B cell lymphoma with or without subsequent disease progression.

Genomic analysis has the potential to both risk-stratify and inform management of patients diagnosed with large B cell lymphomas (LBCL). We analyzed cases of newly diagnosed LBCL patients treated with standard immunochemotherapy from three publicly available cohorts of patients on which fluorescence in situ hybridization (FISH) and next generation sequencing (NGS) were performed to determine the frequency of genomic alterations based upon development of disease progression. Cases from 698 patients were analyzed, with 201 experiencing disease progression and 497 no disease progression by 24 months post-diagnosis. When analyzing for the presence of MYC rearrangement and MYC-BCL2 dual-rearrangement/double hit, as well as variants predicted to result in alteration of protein function in 15 genes common to NGS panels from all 3 cohorts, only MYC rearrangement and TP53 mutation were associated with significantly higher odds of disease progression on multivariate analysis. Additionally, cases from patients who experienced disease progression demonstrated a high frequency of specific genomic alterations when analyzed by cohort or cell of origin classification by immunohistochemistry when available. Individual genomic features of LBCL cases may predict for development of disease progression in newly diagnosed patients treated with standard therapies, as well occur at higher frequencies in cases of disease progression based upon geographic region and/or cell of origin status. These novel findings support efforts to evaluate genomic features as biomarkers for response to specific therapies in subsets of LBCL patients who experience disease progression, which may lead to discovery of more effective treatment options.

Acquired BCL2 variants associated with venetoclax resistance in acute myeloid leukemia.

We report and characterize three venetoclax-resistant BCL2 variants arising during venetoclax/azacitidine therapy in acute myeloid leukemia (AML). Our results indicate the potential for on-target venetoclax resistance in patients with AML at relapse.

Inherited Basaloid Neoplasms Associated With SUFU Pathogenic Variants.

Importance: Germline SUFU pathogenic variants (PVs) have previously been associated with basal cell nevus syndrome (BCNS) and multiple infundibulocystic basal cell carcinoma syndrome; however, a broader spectrum of cutaneous findings in patients with SUFU PVs has not been well delineated. Objective: To define the clinical and histopathologic spectrum of cutaneous findings in patients with germline SUFU PVs. Design, Setting, and Participants: This case series was conducted in multiple US academic dermatology, medical genetics, and medical oncology clinics between July 2014 and July 2022. The study included patients with confirmed germline SUFU PVs who were evaluated by a dermatologist. The analysis took place from March to September 2023. Main Outcomes and Measures: Histopathologic evaluation of skin biopsies with or without immunohistochemical staining, and targeted next-generation sequencing (NGS) on tumor specimens. Results: All 5 patients were women. The mean (range) age at presentation was 50.2 (31-68) years, with skin manifestations initially appearing in the fourth to sixth decades of life. None had keratocystic odontogenic tumors. A total of 29 skin pathology specimens from the 5 patients were reviewed; of these, 3 (10.3%) were diagnosed as basaloid follicular hamartomas (BFHs), 10 (34.5%) classified as infundibulocystic basal cell carcinomas (iBCCs), 6 (20.7%) classified as nodular basal cell carcinomas (nBCCs), and 1 (3.4%) as infiltrative basal cell carcinoma (BCC). Targeted NGS studies on tumor specimens suggest that an increased number of UV-signature variants is associated with basal cell carcinomas compared with more indolent basaloid follicular hamartomas. Conclusions and Relevance: Patients with germline SUFU PVs may present with multiple indolent basaloid neoplasms in addition to conventional basal cell carcinomas, typically appearing in the fourth to sixth decades of life. Although there are overlapping clinical manifestations, these findings help to differentiate the clinical syndrome associated with SUFU PVs from PTCH1 BCNS. Awareness of the clinicopathologic spectrum of SUFU-associated basaloid neoplasms is important for dermatologists and dermatopathologists because many (although not all) of these lesions are indolent and do not require aggressive surgical treatment. Importantly, because SUFU lies downstream of the protein smoothened, vismodegib and other smoothened inhibitors are unlikely to be effective therapies in this subset of patients.

The predictive value of PNH clones, 6p CN-LOH, and clonal TCR gene rearrangement for aplastic anemia diagnosis.

Acquired aplastic anemia (AA) is a life-threatening bone marrow aplasia caused by the autoimmune destruction of hematopoietic stem and progenitor cells. There are no existing diagnostic tests that definitively establish AA, and diagnosis is currently made via systematic exclusion of various alternative etiologies, including inherited bone marrow failure syndromes (IBMFSs). The exclusion of IBMFSs, which requires syndrome-specific functional and genetic testing, can substantially delay treatment. AA and IBMFSs can have mimicking clinical presentations, and their distinction has significant implications for treatment and family planning, making accurate and prompt diagnosis imperative to optimal patient outcomes. We hypothesized that AA could be distinguished from IBMFSs using 3 laboratory findings specific to the autoimmune pathogenesis of AA: paroxysmal nocturnal hemoglobinuria (PNH) clones, copy-number-neutral loss of heterozygosity in chromosome arm 6p (6p CN-LOH), and clonal T-cell receptor (TCR) γ gene (TRG) rearrangement. To test our hypothesis, we determined the prevalence of PNH, acquired 6p CN-LOH, and clonal TRG rearrangement in 454 consecutive pediatric and adult patients diagnosed with AA, IBMFSs, and other hematologic diseases. Our results indicated that PNH and acquired 6p CN-LOH clones encompassing HLA genes have ∽100% positive predictive value for AA, and they can facilitate diagnosis in approximately one-half of AA patients. In contrast, clonal TRG rearrangement is not specific for AA. Our analysis demonstrates that PNH and 6p CN-LOH clones effectively distinguish AA from IBMFSs, and both measures should be incorporated early in the diagnostic evaluation of suspected AA using the included Bayesian nomogram to inform clinical application.

An expanded immunohistochemical profile of osteoclast-rich undifferentiated carcinoma of the urinary tract.

Osteoclast-rich undifferentiated carcinoma of the urinary tract (ORUCUT) is a rare tumor composed of ovoid to spindle-shaped mononuclear cells with intermixed or focally clustered osteoclast-like giant cells. Previous studies have demonstrated that the mononuclear cells are neoplastic cells, while the giant cells are reactive cells of histiocytic lineage. The association between these tumors and classic urothelial carcinomas suggest that the mononuclear cells are derived from urothelial cells; however, no studies have been conducted to assess the immunohistochemical profile of ORUCUT with more specific urothelial markers. This study identified 21 cases of ORUCUT and performed immunohistochemistry for GATA3, uroplakin II, and thrombomodulin along with pancytokeratin (AE1/3) on all cases. Mononuclear cells stained positive in 20 cases (95%) for GATA3 and 19 cases (90%) for thrombomodulin. None of the mononuclear cells were positive for uroplakin II and only three cases showed focal positivity for AE1/3. The osteoclast-like giant cells were negative for GATA3, uroplakin II, thrombomodulin, and AE1/3, providing additional support to a reactive origin for these cells. Additionally, 15 cases (71%) were associated with either in situ or invasive urothelial carcinoma. This study provides an expanded immunohistochemical profile for ORUCUT and more definitively supports a urothelial origin for this tumor.

The Influenza A PB1-F2 and N40 Start Codons Are Contained within an RNA Pseudoknot.

Influenza A is a negative-sense RNA virus with an eight-segment genome. Some segments encode more than one polypeptide product, but how the virus accesses alternate internal open reading frames (ORFs) is not completely understood. In segment 2, ribosomal scanning produces two internal ORFs, PB1-F2 and N40. Here, chemical mapping reveals a Mg(2+)-dependent pseudoknot structure that includes the PB1-F2 and N40 start codons. The results suggest that interactions of the ribosome with the pseudoknot may affect the level of translation for PB1-F2 and N40.

The influenza A segment 7 mRNA 3' splice site pseudoknot/hairpin family.

The 3' splice site of the influenza A segment 7 transcript is utilized to produce mRNA for the critical M2 ion-channel protein. In solution a 63 nt fragment that includes this region can adopt two conformations: a pseudoknot and a hairpin. In each conformation, the splice site, a binding site for the SF2/ASF exonic splicing enhancer and a polypyrimidine tract, each exists in a different structural context. The most dramatic difference occurs for the splice site. In the hairpin the splice site is between two residues that are involved in a 2 by 2 nucleotide internal loop. In the pseudoknot, however, these bases are canonically paired within one of the pseudoknotted helices. The conformational switching observed in this region has implications for the regulation of splicing of the segment 7 mRNA. A measure of stability of the structures also shows interesting trends with respect to host specificity: avian strains tend to be the most stable, followed by swine and then human.

The 3' splice site of influenza A segment 7 mRNA can exist in two conformations: a pseudoknot and a hairpin.

The 3' splice site of influenza A segment 7 is used to produce mRNA for the M2 ion-channel protein, which is critical to the formation of viable influenza virions. Native gel analysis, enzymatic/chemical structure probing, and oligonucleotide binding studies of a 63 nt fragment, containing the 3' splice site, key residues of an SF2/ASF splicing factor binding site, and a polypyrimidine tract, provide evidence for an equilibrium between pseudoknot and hairpin structures. This equilibrium is sensitive to multivalent cations, and can be forced towards the pseudoknot by addition of 5 mM cobalt hexammine. In the two conformations, the splice site and other functional elements exist in very different structural environments. In particular, the splice site is sequestered in the middle of a double helix in the pseudoknot conformation, while in the hairpin it resides in a two-by-two nucleotide internal loop. The results suggest that segment 7 mRNA splicing can be controlled by a conformational switch that exposes or hides the splice site.