Multi-gene measurable residual disease assessed by digital polymerase chain reaction has clinical and biological utility in acute myeloid leukemia patients receiving venetoclax/azacitidine.

Venetoclax with azacitidine (ven/aza) is a lower-intensity therapeutic regimen that has been shown to improve outcomes in elderly patients with acute myeloid leukemia (AML). Measurable residual disease (MRD) using flow cytometry is a valuable tool for the prediction of relapse in AML using conventional therapies and ven/aza; however, the prognostic value for broadscale molecular MRD after ven/aza treatment is less clear. We aimed to determine the utility of retrospective assessment using multi-gene molecular MRD by droplet digital polymerase chain reaction (ddPCR). We found this approach correlates with outcomes in a cohort of patients receiving frontline ven/aza for AML. The predictive value of ddPCR MRD persisted when NPM1 mutations were removed from analysis, as well as after adjustment for the impact of stem cell transplant on outcomes. Late achievement of MRD negativity, including after SCT, was still associated with superior outcomes compared to persistently detectable MRD. We further explored the impact of ven/aza on the burden of different classes of mutations, and identified the persistence of splicing factor mutations, commonly associated with MDS, as a consistent finding after ven/aza treatment. These data add to our understanding of the effects of ven/aza on AML disease biology and provide details on molecular depth of remission that can guide prospective trials in the future.

N-terminus DUX4-immunohistochemistry is a reliable methodology for the diagnosis of DUX4-fused B-lymphoblastic leukemia/lymphoma (N-terminus DUX4 IHC for DUX4-fused B-ALL).

B-lymphoblastic leukemia/lymphoma (B-ALL) is the most common pediatric malignancy and the most commonly diagnosed adult lymphoblastic leukemia. Recent advances have broadened the spectrum of B-ALL, with DUX4 gene fusions implicated in a subclass occurring in adolescents and young adults and harboring a favorable prognosis. DUX4 fusions have been challenging to identify. We aimed to determine whether expression of the DUX4 oncoprotein, as detected by targeted immunohistochemistry, might serve as a surrogate for molecular detection of DUX4 fusions in B-ALL. A cohort of investigational B-ALLs was generated with enrichment for DUX4 fusions by the inclusion of cases with characteristic demographic features and immunophenotypic properties. B-ALLs with mutually exclusive cytogenetics were collected. Immunohistochemical staining by a monoclonal antibody raised against the N-terminus of the DUX4 protein was performed. N-DUX4 immunohistochemistry demonstrated strong, crisp nuclear staining in blasts of seven investigational cases, six of which had nucleic acid material available for molecular evaluation. Five of these cases demonstrated RNA-seq DUX4-fusion positivity. One N-DUX4 immunohistochemistry positive case lacked a definitive DUX4-fusion by RNA-seq, though demonstrated a gene expression profile characteristic of DUX4-rearranged B-ALLs, a CD2+ immunophenotype, and a lack of staining by C-terminus DUX4 antibody immunohistochemistry. At least 83.3% [5/6] positive predictive value. N-DUX4 immunohistochemistry was negative in blasts of three RNA-seq DUX4-fusion-negative cases (3/3; 100% negative predictive value). B-ALLs with mutually exclusive cytogenetic profiles were all N-DUX4 negative (0/10, specificity 100%). N-DUX4 immunohistochemistry is reliable for the distinction of DUX4-rearranged B-ALLs from other B-ALLs. We recommend its use for subclassification of B-ALLs in adolescents and young adults and in B-ALLs that remain "not otherwise specified."

Laboratory testing in BCR-ABL1-like (Philadelphia-like) B-lymphoblastic leukemia/lymphoma.

BCR-ABL1-like B-lymphoblastic leukemia/lymphoma (BCR-ABL1-like B-ALL), also known as Philadelphia-like (Ph-like) ALL, is a neoplasm of B-lineage lymphoblasts characterized by a pattern of gene expression similar to that of B-ALL with the BCR-ABL1 translocation but lacking the BCR-ABL1 fusion protein. The diagnosis of BCR-ABL1-like B-ALL is associated with a high rate of relapse and poor clinical outcomes. In recognition of the difficulty in screening these leukemias for diagnostic workup, the 2016 update/revision to the World Health Organization (WHO) 2008 edition included BCR-ABL1-like B-ALL as a provisional entity. This review addresses the various clinical considerations and methodologies currently used in the pathologic diagnosis, subclassification, and molecular characterization of cases of BCR-ABL1-like B-ALL, with particular attention paid to emerging methods useful in identification of molecular lesions potentially amenable to targeted therapy.

Autoreactive Antibodies Associated with Castleman Disease Triad.

The Castleman triad has been described in a select few patients presenting with a retroperitoneal mass, mucocutaneous pemphigus vulgaris, and bronchiolitis obliterans. Here, we describe the Castleman triad in a 19-year-old male with unicentric hyaline vascular type Castleman disease (HV-CD). This patient presented with an array of positive antibodies, including anti-cyclic citrullinated peptide, anti-double-stranded DNA, and Sjogren's IgG. Interestingly, the patient's rheumatologic symptoms resolved after tumor resection, while his antibody profile remained relatively unchanged. HV-CD, with a triad presentation, was thought to be from a paraneoplastic syndrome secondary to an underlying lymphoproliferative disorder. The findings presented here identify multiple autoantibodies potentially contributing to this patient's presentation with HV-CD.

Epidermal growth factor receptor (EGFR) mutations in small cell lung cancers: Two cases and a review of the literature.

Activating mutations in the epidermal growth factor receptor (EGFR) gene are exceedingly rare in small cell lung cancer (SCLC). We present two cases of SCLC harboring EGFR mutations, one in an 82 year-old male smoker with a combined SCLC and adenocarcinoma with a novel D855H point mutation in exon 21, and the second in a 68 year-old female never smoker with the L858R point mutation in exon 21. The cases, accompanied by a review of the literature, highlight the importance of integration of clinicopathologic considerations and adherence to recently promulgated Guideline recommendations for molecular testing in lung cancer.