Jiang, Liuyan

Key PointsDUSP22-rearranged ALCLs belong to a distinct subset of ALCLs lacking activated STAT3. DUSP22-rearranged ALCLs have a unique molecular signature characterized by DNA hypomethylation and an immunogenic phenotype.

SummaryCD38 is expressed on Waldenström macroglobulinaemia (WM) cells, but its role as a therapeutic target remains undefined. With recent approval of the anti‐CD38 monoclonal antibody, daratumumab (Dara), we hypothesized that blocking CD38 would be lethal to WM cells.In vitroDara treatment of WM cells (including ibrutinib‐resistant lines) elicited antibody‐dependent cellular cytotoxicity (ADCC), complement‐dependent cytotoxicity (CDC), antibody‐dependent cell phagocytosis (ADCP) and direct apoptosis.In vivo, Dara treatment was well tolerated and delayed tumour growth in RPCI‐WM1‐xenografted mice. CD38 is reported to augment B‐cell receptor (BCR) signalling; we noted that Dara significantly attenuated phosphorylated SYK, LYN, BTK, PLCγ2, ERK1/2, AKT, mTOR, and S6 levels, and this effect was augmented by cotreatment with ibrutinib. Indeed, WM cells, including ibrutinib‐resistant WM cell lines treated with the ibrutinib + Dara combination, showed significantly more cell death through ADCC, CDC, ADCP and apoptosis relative to single‐agent Dara or ibrutinib. In summary, we are the first to report thein vitroandin vivoanti‐WM activity of Dara. Furthermore, we show a close connection between BCR and CD38 signalling, which can be co‐targeted with ibrutinib + Dara to induce marked WM cell death, irrespective of acquired resistance to ibrutinib.

Updated WHO criteria define mixed phenotype acute leukemia (MPAL) with more stringent diagnostic criteria than the formerly described entity biphenotypic acute leukemia (BAL). The changes in diagnostic criteria influence management by assigning weight to aberrantly expressed markers and minimizing expression of myeloid markers other than myeloperoxidase (MPO), potentially foregoing consolidative allogeneic transplant for an otherwise “favorable” lymphoid phenotypic leukemia. We present a case of MPO-negative, myeloid antigen-positive acute lymphoblastic leukemia who progressed with refractory phenotypic acute myeloid leukemia while receiving lymphoid-directed therapy and discuss concerns raised by the adoption of the new, more stringent diagnostic criteria for BAL.

AbstractWe conducted a surveillance epidemiology and end results (SEER)‐based analysis to describe the incidence and characteristics of second primary acute lymphoblastic leukemia (sALL) among adults (≥18 years) with a history of primary malignancies (1M). Standardized incidence ratios (SIRs) of sALL cases were calculated by site and 1M stage. We also evaluated the differences in 5‐year sALL survival by age, site, and extent of 1M, latency of sALL after 1M, and evidence of underlying racial/ethnic disparity. We identified 10,956 patients with de‐novo/primary acute lymphoblastic leukemia (1ALL) and 772 with sALL. Women (49.1% vs. 42.9%), white patients (72.0% vs. 59.5%), older patients (58.8% vs. 25.2%; age ≥65 years), and patients diagnosed between 2003 and 2012 (66.8% vs. 53.9%) had a higher proportion of sALL compared with 1ALL. There was a significantly inferior median 5‐year survival for sALL patients compared to 1ALL (6 vs. 15 months; HR 1.20, 95% CI 1.10–1.31, P < 0.001). The median latency period was 60.0 months; the most common 1M among sALL patients were breast (17.9%) and prostate (17.4%). Patients with any 1M were at increased risk of developing sALL (SIR 1.76, 95% CI 1.58–1.95, P < 0.001). Hematological‐1M sites had significantly higher SIRs (hematological‐SIR 7.35; solid‐SIR 1.33; P < 0.001). We observed a significant increase in sALL incidence after a 1M and a significantly worse 5‐year survival with different demographic characteristics from 1ALL. There is a need to define appropriate screening methods for patients surviving their primary cancer.

Primary central nervous system (PCNSL) lymphoma is an aggressive extranodal non-Hodgkin lymphoma, and most cases are classified as diffuse large B-cell lymphoma (DLBCL) by histology. T-cell/histiocyte-rich large B-cell lymphoma (TCRLBCL) represents a distinct subtype of diffuse large B-cell lymphoma and is characterized by the presence of scattered large neoplastic B-cells in a background of abundant T-cells and histiocytes. This is in contrast to the dense perivascular cuffing of neoplastic B-cells in classic DLBCL. T-cell/histiocyte-rich large B-cell lymphoma should be considered in PCNSL cases in which neoplastic B-cells are sparse and scattered. Immunohistochemistry will help identify the B-cells and surrounding infiltrate rich in Tlymphocytes and histiocytes. Future studies exploring the biology of TCRLBCL and the crosstalk between the neoplastic cells and the surrounding inflammatory infiltrate may provide exciting prospects for future therapies for TCRLBCL.

Rosai-Dorfman disease (RDD) is a rare, benign histiocyte disorder originally described by Rosai and Dorfman in 1969 as sinus histiocytosis with massive lymphadenopathy. It most typically presents as massive, painless cervical lymphadenopathy, and it is most often found in adolescents and young adults. Extranodal involvement is a common feature of RDD and may occur in more than 40% of patients. Less commonly, the disease can be seen in the bone. There are scattered case reports discussing the use of radiotherapy in the treatment of RDD. Here, we present a case of extranodal RDD of the femur in a 49-year-old African American female. The patient underwent three surgical procedures prior to undergoing radiotherapy. Pathology was consistent with extranodal RDD. The cells stained positive for CD68 and S-100. Pathognomonic features such as emperipolesis and replacement of the bone marrow by diffuse infiltrating of histiocytes and intervening bands of plasma cells proliferation were noted. Prior to radiotherapy, the patient required a walker to assist with ambulation and was utilizing a wheelchair while in the clinic. The decision was made to proceed with 30 Gy of external beam radiotherapy in 15 fractions. After five fractions, the patient's pain resolved entirely. She no longer required pain medication and was ambulating without assistance. She experienced no adverse events from the radiation. Extranodal RDD is a rare disorder, and evidence for treatment is derived from scattered case reports. Previous reports have indicated a dose response to radiotherapy in the 20-30 Gy range for RDD; however, our patient developed complete resolution of her symptoms after 10 Gy. While the optimal dose regimen has not yet been established, symptomatic patients appear to benefit from external beam radiotherapy for extranodal RDD.

Key Points ALK-negative ALCLs have chromosomal rearrangements of DUSP22 or TP63 in 30% and 8% of cases, respectively. DUSP22-rearranged cases have favorable outcomes similar to ALK-positive ALCLs, whereas other genetic subtypes have inferior outcomes.

AbstractPrimary testicular non‐Hodgkin lymphoma (NHL) is a rare entity with the most common histologic subtype consisting of diffuse large B‐cell lymphoma (DLBCL). Patients with primary testicular lymphoma (PTL) have a poor prognosis and a higher propensity for relapse. Also rare are composite lymphomas (CL) defined as two or more morphologically and phenotypically distinct lymphomas coexisting in a single organ or tissue. Here we present the first reported case of primary testicular composite lymphoma consisting of DLBCL and mantle cell lymphoma (MCL).