Aleukemic Chronic Myeloid Leukemia Without Neutrophilia and Thrombocytosis: A Report From the BCR::ABL1 Pathology Group.

Chronic myeloid leukemia (CML) is characterized by leukocytosis with left-shifted neutrophilia, basophilia, eosinophilia, and variable thrombocytosis. However, extremely rare cases of patients with CML without significant leukocytosis and thrombocytosis (aleukemic phase [ALP] CML, or CML-ALP) have been reported. Due to its rarity and limited awareness, there remains a significant knowledge gap concerning the pathologic diagnosis, disease progression, and optimal patient management and outcomes. In this multi-institutional study, we investigated 31 patients with CML-ALP. Over half (54.8%) of patients had a history of or concurrent hematopoietic or nonhematopoietic malignancies. At time of diagnosis of CML-ALP, approximately 26.7% of patients exhibited neutrophilia, 56.7% had basophilia, and 13.3% showed eosinophilia. The median number of metaphases positive for t(9;22)(q34;q11.2) was 15, with a median of 38.5% of interphase nuclei positive for BCR::ABL1 by fluorescence in situ hybridization. The median BCR::ABL1 level was 26.14%. Remarkably, 14 (45.2%) patients were initially misdiagnosed or not diagnosed before karyotype or fluorescence in situ hybridization information for BCR::ABL1 became available. Twenty-five patients received tyrosine kinase inhibitors (TKIs). One patient developed blast crisis while on TKI treatment 8 months after initial diagnosis. With a median follow-up time of 46.1 months, 20 of 22 patients who received TKI therapy and had detailed follow-up information achieved complete cytogenetic remission or deeper, 15 achieved major molecular remission or deeper, and 10 achieved molecularly undetectable leukemia. In conclusion, given the frequent occurrence of prior or concurrent malignancies, aleukemic presentation, and low level of t(9;22)(q34;q11.2)/BCR::ABL1, misdiagnosis or delayed diagnosis is common among these patients. While these patients generally respond well to TKIs, rare patients may develop blastic transformation. It is therefore important for pathologists and hematologists to be aware of this highly unusual presentation of CML to ensure timely diagnosis and appropriate management.

DUSP22 rearrangement is associated with a distinctive immunophenotype but not outcome in patients with systemic ALK-negative anaplastic large cell lymphoma.

DUSP22 rearrangement (R) has been associated with a favorable outcome in systemic ALK-negative anaplastic large cell lymphoma (ALCL). However, a recent study found that patients with DUSP22-R ALK-negative ALCL have a poorer prognosis than was reported initially. In this study, we compared the clinicopathological features and outcomes of patients with ALKnegative ALCL with DUSP22-R (n=22) versus those without DUSP22-R (DUSP22-NR; n=59). Patients with DUSP22-R ALCL were younger than those with DUSP22-NR neoplasms (P=0.049). DUSP22-R ALK-negative ALCL cases were more often positive for CD15, CD8, and less frequently expressed pSTAT3Tyr705, PD-L1, granzyme B and EMA (all P<0.05). TP63 rearrangement (TP63-R) was detected in three of the 66 (5%) ALK-negative ALCL cases tested and none of these cases carried the DUSP22-R. Overall survival of patients with DUSP22-R ALCL was similar to that of the patients with DUSP22-NR neoplasms regardless of International Prognostic Index score, stage, age, or stem cell transplantation status (all P>0.05), but was significantly shorter than that of the patients with ALK-positive ALCL (median overall survival 53 months vs. undefined, P=0.005). Five-year overall survival rates were 40% for patients with DUSP22-R ALCL versus 82% for patients with ALK-positive ALCL. We conclude that DUSP22-R neoplasms represent a distinctive subset of ALK-negative ALCL. However, in this cohort DUSP22-R was not associated with a better clinical outcome. Therefore, we suggest that current treatment guidelines for this subset of ALK-negative ALCL patients should not be modified at present.

Small cell/lymphohistiocytic morphology is associated with peripheral blood involvement, CD8 positivity and retained T-cell antigens, but not outcome in adults with ALK+ anaplastic large cell lymphoma.

Several morphologic variants of ALK+ anaplastic large cell lymphoma (ALCL) are recognized. The small cell (SC) and lymphohistiocytic (LH) variants are reported to be associated with poorer outcome in children with ALK + ALCL. In this study of 102 adults with ALK + ALCL, there were 18 (18%) cases of SC and/or LH variants. Patients with SC/LH ALK + ALCL more often had peripheral blood involvement than patients with non-SC/LH neoplasms (60% vs 0%, p = 0.02). There were no other significant differences in clinical features between patients with SC/LH versus non-SC/LH ALK + ALCL. Compared with non-SC/LH cases of ALK + ALCL, neoplasms with SC/LH features were more often positive for CD2 (92% vs. 36%, p = 0.0007), CD3 (81% vs. 15%, p = 0.0001), CD7 (80% vs. 37%, p = 0.03), and CD8 (54% vs. 7%, p = 0.0006). There were no other significant differences in the immunophenotype between SC/LH and non-SC/LH ALK + ALCL cases. The initial chemotherapy regimens and the response rates were similar between patients with ALK + ALCL with SC/LH patterns versus those with non-SC/LH patterns. After a median follow-up of 30.8 months (range, 0.3-208 months), patients with high (>3) International Prognostic Index (IPI) scores had significantly shorter overall survival than patients with low (<3) IPI scores (p = 0.003). However, there was no significant difference in overall or progression-free survival between patients with SC/LH versus non-SC/LH ALK + ALCL (p = 0.99 and p = 0.94, respectively). We conclude that, in adults with ALK + ALCL, SC and LH variants are associated with peripheral blood involvement and a CD8 + immunophenotype with retention of T-cell markers (CD2, CD3, and CD7). However, in contrast with children with ALK + ALCL, SC and LH variants appear to have no impact on prognosis in adults with ALK + ALCL.

Immunohistochemical loss of enhancer of Zeste Homolog 2 (EZH2) protein expression correlates with EZH2 alterations and portends a worse outcome in myelodysplastic syndromes.

EZH2 coding mutation (EZH2MUT), resulting in loss-of-function, is an independent predictor of overall survival in MDS. EZH2 function can be altered by other mechanisms including copy number changes, and mutations in other genes and non-coding regions of EZH2. Assessment of EZH2 protein can identify alterations of EZH2 function missed by mutation assessment alone. Precise evaluation of EZH2 function and gene-protein correlation in clinical MDS cohorts is important in the context of upcoming targeted therapies aimed to restore EZH2 function. In this study, we evaluated the clinicopathologic characteristics of newly diagnosed MDS patients with EZH2MUT and correlated the findings with protein expression using immunohistochemistry. There were 40 (~6%) EZH2MUT MDS [33 men, seven women; median age 74 years (range, 55-90)]. EZH2 mutations spanned the entire coding region. Majority had dominant EZH2 clone [median VAF, 30% (1-92)], frequently co-occurring with co-dominant TET2 (38%) and sub-clonal ASXL1 (55%) and RUNX1 (43%) mutations. EZH2MUT MDS showed frequent loss-of-expression compared to EZH2WT (69% vs. 27%, p = 0.001). Interestingly, NINE (23%) EZH2WT MDS also showed loss-of-expression. EZH2MUT and loss-of-expression significantly associated with male predominance and chr(7) loss. Further, only EZH2 loss-of-expression patients showed significantly lower platelet counts, a trend for higher BM blast% and R-IPSS scores. Over a 14-month median follow-up, both EZH2MUT (p = 0.027) and loss-of-expression (p = 0.0063) correlated with poor survival, independent of R-IPSS, age and gender. When analyzed together, loss-of-expression showed a stronger correlation than mutation (p = 0.061 vs. p = 0.43). In conclusion, immunohistochemical assessment of EZH2 protein, alongside mutation, is important for prognostic workup of MDS.

Improved outcomes among newly diagnosed patients with FMS-like tyrosine kinase 3 internal tandem duplication mutated acute myeloid leukemia treated with contemporary therapy: Revisiting the European LeukemiaNet adverse risk classification.

Mutations in fms-like tyrosine kinase 3 (FLT3) gene are common genomic alterations in acute myeloid leukemia (AML). FLT3 internal tandem duplication mutations (FLT3-ITD) have consistently been shown to be adversely prognostic, particularly those with high allelic ratio (AR). Current AML treatment strategies, including high dose cytarabine, purine analogs, FLT3 inhibitors (FLT3i), and with or without allogeneic stem cell transplant (SCT) have been shown to improve the outcomes in patients with FLT3 mutations. We analyzed a consecutive cohort of newly diagnosed patients with AML treated at a large academic medical center from January 2012 to January 2020. A total of 1576 patients with a new diagnosis of AML were reviewed. Among these, 1438 (91%) had molecular testing for FLT3 mutations and 21% (304/1438) had an FLT3 mutation, including 17% with an FLT3-ITD mutation. We show that FLT3-ITD high AR with NPM1 wild-type have significantly improved survival compared with other European LeukemiaNet (ELN) adverse risk disease. In multivariable cox proportional hazards model of patients receiving intensive or low-intensity induction regimens, FLT3 mutations did not have prognostic significance. The use of allogeneic SCT in CR1 for patients with FLT3 mutations appears to improve survival, particularly in those with ELN adverse risk disease. Overall, this data highlights the changing prognostic impact of FLT3 mutations in a contemporary era with appropriate use of induction therapy combined with targeted agents and allogenic SCT.

Prediction of survival with intensive chemotherapy in acute myeloid leukemia.

Progress with intensive chemotherapy and supportive care measures has improved survival in newly diagnosed acute myeloid leukemia (AML). Predicting outcome helps in treatment decision making. We analyzed survival as the treatment endpoint in 3728 patients with newly diagnosed AML treated with intensive chemotherapy from 1980 to 2021. We divided the total study group (3:1 basis) into a training (n = 2790) and a validation group (n = 938). The associations between survival and 27 characteristics were investigated. In the training cohort, the multivariate analysis identified 12 consistent adverse prognostic variables independently associated with worse survival: older age, therapy-related myeloid neoplasm, worse performance status, cardiac comorbidity, leukocytosis, anemia, thrombocytopenia, elevated creatinine and lactate dehydrogenase, cytogenetic abnormalities, and the presence of infection at diagnosis except fever of unknown origin. We categorized patients into four prognostic groups, favorable (7%), intermediate (43%), poor (39%), and very poor (11%) with estimated 5-year survival rates of 69%, 36%, 13%, and 3% respectively (p < .001). The predictive model was validated in an independent cohort. In a subset of patients with molecular mutation profiles, adding the mutation profiles after accounting for the effects of previous factors identified NPM1 (favorable), PTPN11, and TP53 (both unfavorable) mutations as molecular prognostic factors. The new proposed predictive model for survival with intensive chemotherapy in patients with AML is robust and can be used to advise patients regarding their prognosis, to modify therapy in remission (e.g., proposing allogeneic stem cell transplantation in first remission), and to compare outcome and benefits on future investigational therapies.

MALT lymphoma of the tongue: An unusual site that may present a diagnostic challenge.

Extranodal marginal zone lymphoma of mucosa-associated lymphoid tissue (MALT lymphoma) is a low-grade B cell lymphoma that can affect any organ, usually preceded by acquisition of MALT in response to antigenic stimulus provided by infections or autoimmune diseases. Most often, MALT lymphoma involves the stomach (about 35% of cases), followed by the ocular adnexal region, skin, lungs, and salivary glands, but virtually any extranodal site can be involved. MALT lymphomas are less common at sites of normal MALT tissue, such as Waldeyer ring and the ileocecal region of the gastrointestinal tract. Lymphomas involving the tongue are extremely rare and represent approximately 3% of all lymphomas involving the head and neck region. In this study, we discuss potentially challenging diagnostic aspects of MALT lymphoma involving the tongue and review and summarize the available literature about this topic.

Value and pitfalls of assessing bone marrow morphologic findings to predict response in patients with myelofibrosis who undergo hematopoietic stem cell transplantation.

BACKGROUND: Allogeneic hematopoietic stem cell transplantation (allo-HSCT) is a curative option for patients with myelofibrosis (MF). Bone marrow (BM) morphologic evaluation of myelofibrosis following allo-HSCT is known to be challenging in this context because resolution of morphologic changes is a gradual process. PATIENTS AND METHODS: We compared BM samples of patients with myelofibrosis who underwent first allo-HSCT and achieved molecular remission by day 100 with BM samples of patients who continued to have persistent molecular evidence of disease following allo-HSCT. RESULTS: The study group included 29 patients: 17 primary MF, 7 post-polycythemia vera (PV) MF, and 5 post-essential thrombocythemia (ET) MF. In this cohort there were 18 JAK2 p.V617F, 8 CALR; 1 MPL, and 2 patients had concurrent JAK2 p.V617F and MPL mutations. The control group included 5 patients with primary MF, one with post-PV MF, one with post-ET MF (5 JAK2 p.V617F; 2 CALR). Following allo-HSCT, both groups showed reduction in BM cellularity and number of megakaryocytes. The study cohort also less commonly had dense megakaryocyte clusters and endosteal located megakaryocytes and showed less fibrosis. There was no statistical difference in BM cellularity, presence of erythroid islands, degree of osteosclerosis, or megakaryocyte number, size, nuclear lobation, presence of clusters or intrasinusoidal location. CONCLUSIONS: Following allo-HSCT at 100 days, morphologic evaluation of BM in patients with MF cannot reliably predict persistence versus clearance of molecular evidence of MF. Disappearance of BM MF, dense megakaryocyte clusters, and endosteal localization of megakaryocytes are suggestive of disease response.

The survival impact of CKS1B gains or amplification is dependent on the background karyotype and TP53 deletion status in patients with myeloma.

Gains or amplification (amp) of chromosome 1q21/CKS1B are reported to be a high-risk factor in myeloma. In this retrospective study, we analyzed the impact of CKS1B gain/amp on overall survival in the context of other genetic aberrations, such as TP53 deletion, FGFR3-IGH, IGH-MAF, MYEOV/CCND1-IGH, and RB1, as well as karyotype. The cohort included 132 myeloma patients with CKS1B gain/amp detected by fluorescence in-situ hybridization. There were 72 men and 60 women with a median age of 65 years (range 39-88 years). A normal, simple, or complex karyotype was observed in 39.5%, 5.4%, and 55% of patients, respectively. "Double hit," defined as CKS1B gain/amp coexisting with TP53 deletion, or "triple hit," defined as double hit plus t(4;14)FGFR3-IGH or t(14;16)IGH-MAF, were identified in 25 patients (18.9%) and five patients (3.8%), respectively. Double and triple hit were highly associated with a complex karyotype (p = 0.02). Ninety-nine patients (99/128, 77.3%) received stem cell transplantation. The median follow-up time was 48.2 months (range 2-104 months); 68 patients (51.5%) died, with a median overall survival of 58.8 months. Multivariate analysis (Cox model) showed that double hit with TP53 deletion (p = 0.0031), triple hit (p = 0.01), and complex karyotype (p = 0.0009) were each independently associated with poorer overall survival. Stem cell transplantation was associated with better overall survival, mainly in patients with a double or triple hit and complex karyotype (p = 0.003). These findings indicate that the inferior outcome of myeloma patients with CKS1B gain/amp is attributable to the high number of high-risk patients in this group. The prognostic impact of CKS1B gain/amp depends on the background karyotype and TP53 status.

Outcome of T-cell acute lymphoblastic leukemia/lymphoma: Focus on near-ETP phenotype and differential impact of nelarabine.

Early T-cell precursor acute lymphoblastic leukemia/lymphoma (ETP-ALL/LBL) is characterized by a distinct immunophenotype (CD1a-negative, CD8-negative, CD5-negative or weak-positive <75%, myeloid/stem-cell markers positive) and poor clinical outcomes. Near-ETP ALL is transcriptionally similar to ETP-ALL but CD5 expression level is not low enough to meet the criteria of ETP immunophenotype. Outcomes of near-ETP ALL are not well characterized. We reviewed 171 patients with newly-diagnosed T-ALL/LBL. Patients were categorized into three groups; ETP (N = 27), near-ETP (N = 24), and non-ETP ALL/LBL (N = 120). ETP-ALL/LBL was associated with a significantly worse survival compared with non-ETP ALL/LBL: 5-year overall survival (OS) rates 32% versus 63% (p < .001). Outcome was similar between near-ETP and non-ETP ALL/LBL: 5-year OS rates 56% versus 63% (p = .543). Landmark analysis showed that allogeneic stem cell transplant (allo-SCT) in first remission was beneficial in ETP-ALL/LBL (5-year event-free survival rates 36% versus 18%, p = .030) but not in near-ETP or non-ETP ALL/LBL. Multivariate analysis selected the following as significant independent prognostic factors for OS: age ≥ 60 years (HR 3.11; p = .003); elevated WBC ≥100 × 109 /L (HR 2.60; p = .005); and ETP immunophenotype (HR 2.29; p = .010). A survival advantage with adding nelarabine to hyper-CVAD was observed in non-ETP ALL (5-year OS rates 83% versus 38% with hyper-CVAD plus neralabine versus hyper-CVAD, p = .003). In conclusion, outcome of ETP-ALL/LBL was poor and improved with allo-SCT; outcome of near-ETP ALL/LBL was similar to non-ETP ALL/LBL; the addition of nelarabine to hyper-CVAD improved the survival in non-ETP ALL only.

From the archives of MD Anderson Cancer Center: Concurrent BCR-ABL1 and CRLF2 rearrangements in B-lymphoblast phase of chronic myeloid leukemia.

The t(9;22)(q34;q11.2), also known as the Philadelphia (Ph) chromosome, results in BCR-ABL1 fusion residing on the derivative chromosome 22. This translocation is characteristic of chronic myeloid leukemia, but also can occur in a substantial subset of B acute lymphoblastic leukemia (B-ALL) cases. Ph-like B-ALL has a gene expression profile similar to that of BCR-ABL1 positive/Ph-positive B-ALL, but by definition Ph-like B-ALL does not have the sentinel BCR-ABL1 or the Ph chromosome. About half of Ph-like B-ALL cases carry CRLF2 rearrangements. Rare cases of de novo B-ALL with co-occurrence of BCR-ABL1 and CRLF2 rearrangements have been described. To our knowledge, this is the first report of concurrent BCR-ABL1 and CRLF2 rearrangements in blast phase of chronic myeloid leukemia. In this patient, CRLF2 rearrangement was acquired at the time of disease progression to B-lymphoblast phase of chronic myeloid leukemia. We also review the literature and discuss the distinct clinicopathologic, and genomic characteristics of CRLF2 rearranged B-ALL.

Lymphoid enhancer binding factor 1 (LEF1) expression is significantly higher in Hodgkin lymphoma associated with Richter syndrome relative to de novo classic Hodgkin lymphoma.

Lymphoid enhancer binding factor 1 (LEF1) is consistently upregulated in chronic lymphocytic leukemia (CLL) and in a subset of large B cell lymphoma. Knowledge of LEF1 expression in Hodgkin lymphoma is limited. In this study, we used immunohistochemistry to survey LEF1 expression in various subsets of Hodgkin lymphoma, de novo classic Hodgkin lymphoma (CHL) (n = 43), Hodgkin lymphoma associated with Richter syndrome (HL-RS) (n = 20), and nodular lymphocyte predominant Hodgkin lymphoma (NLPHL) (n = 9). LEF1 expression was significantly higher in HL-RS compared with de novo CHL (12/20, 60% vs. 12/43, 28%; p = 0.0248). Only a single case (1/9; 11%) of NLPHL showed LEF1 expression. Epstein-Barr virus encoded RNA (EBER) was detected in 17 (40%) cases of de novo CHL and 14 (70%) HL-RS. Notably, we identified a correlation between LEF1 expression and EBER positivity (p = 0.0488). We concluded that LEF1 is commonly positive in CHL but not in NLPHL, and such a distinction may be helpful in this differential diagnosis. The higher frequency of LEF1 upregulation in HL-RS relative to de novo CHL suggests that these neoplasms might have different underlying pathogenic mechanisms and warrants further investigation.

B-cell lymphomas associated with breast implants: Report of three cases and review of the literature.

Since the first reported case in 1997, over 600 women with breast implant-associated anaplastic large cell lymphoma (BI ALCL) have been reported. BI ALCL is a CD30-positive T-cell lymphoma that carries clonal T-cell receptor gene rearrangements, and a subset of cases harbors mutations in the JAK-STAT signaling pathway. Rarely, other histologic types of lymphoma have been reported in association with breast implants, including fewer than 10 cases of B-cell origin. Here, we describe three additional patients with B-cell lymphoma occurring around breast implants. Two of these patients developed extranodal marginal zone lymphoma in the peri-implant capsule, one of which had a concurrent ALCL within the superficial lining of the capsule. The third patient presented with diffuse large B-cell lymphoma inside the breast parenchyma surrounding her implant. Determining the etiology and risk factors for the development of B-cell lymphomas associated with breast implants remains challenging, given the wide spectrum of histologic features and the rarity of these neoplasms. Ultimately, we document three new cases of B-cell lymphoma arising around breast implants and highlight their clinical and pathologic features in order to expand our understanding of this rare disease presentation.

High-grade B-cell lymphomas with TdT expression: a diagnostic and classification dilemma.

Mature B-cell neoplasms and immature or precursor B-cell neoplasms need to be distinguished because these patients usually require different therapeutic approaches. B-cell neoplasms that express TdT without unequivocal other features of immaturity may therefore present a diagnostic challenge. We describe 13 patients with TdT-positive aggressive B-cell lymphoma. The clinicopathologic features of these patients were highly heterogeneous, but for the purpose of this study we grouped these cases as follows: (1) de novo high-grade B-cell lymphoma with MYC, BCL2, and/or BCL6 rearrangements (double-hit or triple-hit lymphoma) with TdT expression. In this group we included two cases of de novo composite lymphoma in which there were components of diffuse large B-cell lymphoma and TdT-positive blastic B-cell lymphoma; (2) TdT-positive aggressive B-cell lymphoma arising in patients who previously had follicular lymphoma; (3) initial relapse of TdT-negative aggressive B-cell lymphoma in patients who previously had follicular lymphoma, followed by relapses in which the neoplasm acquired TdT expression; and (4) mature B-cell lymphomas that acquired TdT expression at relapse. This group included one case of EBV-positive diffuse large B-cell lymphoma and one case of pleomorphic variant mantle cell lymphoma. All patients in this study had an aggressive clinical course and a dismal outcome despite appropriate therapy. Rather than "squeezing" these cases into current World Health Organization classification categories, we suggest the use of a descriptive term such as high-grade B-cell lymphoma with TdT expression. In these tumors, the cytogenetic findings and poor prognosis of this patient subgroup suggest that these neoplasms need to be distinguished from B-lymphoblastic leukemia/lymphoma. Segregation of these neoplasms also may foster additional research on these neoplasms.

Ph-like acute lymphoblastic leukemia: a high-risk subtype in adults.

Philadelphia chromosome (Ph)-like acute lymphoblastic leukemia (ALL) is a high-risk subtype of ALL in children. There are conflicting data on the incidence and prognosis of Ph-like ALL in adults. Patients with newly diagnosed B-cell ALL (B-ALL) who received frontline chemotherapy at MD Anderson Cancer Center underwent gene expression profiling of leukemic cells. Of 148 patients, 33.1% had Ph-like, 31.1% had Ph+, and 35.8% had other B-ALL subtypes (B-other). Within the Ph-like ALL cohort, 61% had cytokine receptor-like factor 2 (CRLF2) overexpression. Patients with Ph-like ALL had significantly worse overall survival (OS), and event-free survival compared with B-other with a 5-year survival of 23% (vs 59% for B-other, P = .006). Sixty-eight percent of patients with Ph-like ALL were of Hispanic ethnicity. The following were associated with inferior OS on multivariable analysis: age (hazard ratio [HR], 3.299; P < .001), white blood cell count (HR, 1.910; P = .017), platelet count (HR, 7.437; P = .005), and Ph-like ALL (HR, 1.818; P = .03). Next-generation sequencing of the CRLF2+ group identified mutations in the JAK-STAT and Ras pathway in 85% of patients, and 20% had a CRLF2 mutation. Within the CRLF2+ group, JAK2 mutation was associated with inferior outcomes. Our findings show high frequency of Ph-like ALL in adults, an increased frequency of Ph-like ALL in adults of Hispanic ethnicity, significantly inferior outcomes of adult patients with Ph-like ALL, and significantly worse outcomes in the CRLF2+ subset of Ph-like ALL. Novel strategies are needed to improve the outcome of these patients.

CD123 expression patterns and selective targeting with a CD123-targeted antibody-drug conjugate (IMGN632) in acute lymphoblastic leukemia.

The potential of CD123-targeted therapies in acute lymphoblastic leukemia/lymphoma remains largely unexplored. We examined CD123 expression levels in a large cohort of patients with acute lymphoblastic leukemia/lymphoma and assessed the in vitro impact of IMGN632, a conjugate of CD123-binding antibody with a novel DNA-alkylating payload. CD123 expression on leukemic blasts was surveyed using multicolor/multiparameter flow cytometry. The in vitro effect of IMGN632 was evaluated on B acute lymphoblastic leukemia/lymphoma cell lines and primary B acute lymphoblastic leukemia/lymphoma blasts. The study cohort (n=213) included 183 patients with B acute lymphoblastic leukemia/lymphoma and 30 with T acute lymphoblastic leukemia/lymphoma. CD123 expression was more prevalent in B acute lymphoblastic leukemia/lymphoma than in T acute lymphoblastic leukemia/lymphoma (164/183, 89.6% versus 13/30, 43.3%; P<0.0001), and within B acute lymphoblastic leukemia/lymphoma CD123 expression was more prevalent in Philadelphia chromosome-positive patients than in Philadelphia chromosome-negative patients (96.6% versus 86.3%; P=0.033). In T acute lymphoblastic leukemia/lymphoma, 12/13 (92.3%) patients with CD123-positive blasts had either early T precursor (ETP) or early non-ETP immunophenotype. IMGN632 was highly cytotoxic to B acute lymphoblastic leukemia/lymphoma cell lines, with half maximal inhibitory concentrations (IC50) between 0.6 and 20 pM. In five of eight patients' samples, low picomolar concentrations of IMGN632 eliminated more than 90% of the B acute lymphoblastic leukemia/lymphoma blast population, sparing normal lymphocytes. In conclusion, CD123 expression is prevalent across acute lymphoblastic leukemia/lymphoma subtypes, and the CD123-targeted antibody-drug conjugate IMGN632 demonstrates promising selective activity in preclinical models of B acute lymphoblastic leukemia/lymphoma.

Proteomic Profiling of Signaling Networks Modulated by G-CSF/Plerixafor/Busulfan-Fludarabine Conditioning in Acute Myeloid Leukemia Patients in Remission or with Active Disease prior to Allogeneic Stem Cell Transplantation.

To characterize intracellular signaling in peripheral blood (PB) cells of acute myeloid leukemia (AML) patients undergoing pretransplant conditioning with CXCR4 inhibitor plerixafor, granulocyte colony-stimulating factor (G-CSF), and busulfan plus fludarabine (Bu+Flu) chemotherapy, we profiled 153 proteins in 33 functional groups using reverse phase protein array. CXCR4 inhibition mobilized AML progenitors and clonal AML cells, and this was associated with molecular markers of cell cycle progression. G-CSF/plerixafor and G-CSF/plerixafor/Bu+Flu modulated distinct signaling networks in AML blasts of patients undergoing conditioning with active disease compared to nonleukemic PB cells of patients in remission. We identified AML-specific proteins that remained aberrantly expressed after chemotherapy, representing putative chemoresistance markers in AML.

The efficacy of omalizumab in Cutaneous Mastocytosis: A case series.

BACKGROUND: Mastocytosis describes a heterogeneous group of disorders arising from a clonal proliferation of mast cells. Given the lack of curative treatments for the cutaneous form, there is a significant need for superior therapies. Omalizumab is a recombinant DNA-derived humanized IgG monoclonal antibody that selectively binds to human immunoglobulin E (IgE). It represents a potential treatment for the management of cutaneous mastocytosis, which currently has no standard treatment. METHODS: Two patients were treated with subcutaneous omalizumab 300 mg every 4 weeks. DISCUSSION: Patient 1 experienced 50% reduction in cutaneous infiltration and moderate improvement in pruritus. Patient 2 underwent 90% complete clearance of cutaneous lesions and reported full resolution of pruritus. The median duration of treatment was 24 weeks and time to response was 8 weeks. No significant changes in tryptase levels were observed. Both patients experienced injection site reactions. CONCLUSION: We provide evidence from two cases supporting the efficacy of IgE-mediated therapy in the treatment of cutaneous mastocytosis. Even at a higher-than-standard dose (300 mg vs. 150 mg), the drug was well-tolerated. As we await the results of pivotal clinical trials, omalizumab appears to be a promising treatment option in patients with cutaneous mastocytosis unresponsive to traditional therapies.

MYC/BCL2/BCL6 triple hit lymphoma: a study of 40 patients with a comparison to MYC/BCL2 and MYC/BCL6 double hit lymphomas.

High-grade B-cell lymphomas with MYC, BCL2, and BCL6 rearrangements (triple hit lymphoma) are uncommon. We studied the clinicopathologic features of 40 patients with triple hit lymphoma and compared them to 157 patients with MYC/BCL2 double hit lymphoma and 13 patients with MYC/BCL6 double hit lymphoma. The triple hit lymphoma group included 25 men and 15 women with a median age of 61 years (range, 34-85). Nine patients had a history of B-cell lymphoma. Histologically, 23 (58%) cases were diffuse large B-cell lymphoma and 17 cases had features of B-cell lymphoma, unclassifiable, with features intermediate between diffuse large B-cell lymphoma and Burkitt lymphoma. Most cases of triple hit lymphoma were positive for CD10 (100%), BCL2 (95%), BCL6 (82%), MYC (74%), and 71% with MYC and BCL2 coexpression. P53 was overexpressed in 29% of triple hit lymphoma cases. The clinicopathological features of triple hit lymphoma patients were similar to patients with MYC/BCL2 and MYC/BCL6 double hit lymphoma, except that triple hit lymphoma cases were more often CD10 positive compared with MYC/BCL6 double hit lymphoma (p < 0.05). Induction chemotherapy used was similar for patients with triple hit lymphoma and double hit lymphoma and overall survival in triple hit lymphoma patients was 17.6 months, similar to the overall survival of patients with double hit lymphoma (p = 0.67). Patients with triple hit lymphoma showing P53 overexpression had significantly worse overall survival compared with those without P53 overexpression (p = 0.04). On the other hand, double expressor status and prior history of B-cell lymphoma did not correlate with overall survival. In conclusion, most patients with triple hit lymphoma have an aggressive clinical course and poor prognosis and these tumors have a germinal center B-cell immunophenotype, similar to patients with double hit lymphomas. P53 expression is a poor prognostic factor in patients with triple hit lymphoma.

Secondary Philadelphia chromosome acquired during therapy of acute leukemia and myelodysplastic syndrome.

The Philadelphia chromosome resulting from t(9;22)(q34;q11.2) or its variants is a defining event in chronic myeloid leukemia. It is also observed in several types of de novo acute leukemia, commonly in B lymphoblastic leukemia, and rarely in acute myeloid leukemia, acute leukemia of ambiguous lineage, and T lymphoblastic leukemia. Acquisition of the Philadelphia chromosome during therapy of acute leukemia and myelodysplastic syndrome is rare. We reported 19 patients, including 11 men and 8 women with a median age of 53 years at initial diagnosis. The diagnoses at initial presentation were acute myeloid leukemia (n = 11), myelodysplastic syndrome (n = 5), B lymphoblastic leukemia (n = 2), and T lymphoblastic leukemia (n = 1); no cases carried the Philadelphia chromosome. The Philadelphia chromosome was detected subsequently at relapse, or at refractory stage of acute leukemia or myelodysplastic syndrome. Of 14 patients evaluated for the BCR-ABL1 transcript subtype, 12 had the e1a2 transcript. In 11 of 14 patients, the diseases before and after emergence of the Philadelphia chromosome were clonally related by karyotype or shared gene mutations. Of 15 patients with treatment information available, 7 received chemotherapy alone, 5 received chemotherapy plus tyrosine kinase inhibitors, 2 received tyrosine kinase inhibitors only, and 1 patient was not treated. Twelve patients had follow-up after acquisition of the Philadelphia chromosome; all had persistent/refractory acute leukemia. Thirteen of 15 patients died a median of 3 months after the emergence of the Philadelphia chromosome. In summary, secondary Philadelphia chromosome acquired during therapy is rare, and is associated with the e1a2 transcript subtype, terminal disease stage, and poor outcome.