Blastic plasmacytoid dendritic cell neoplasm: a single-center experience. Clinical characterization, mutational landscape, and clinical outcome of patients undergoing hematopoietic stem cell transplantation intensive therapy.

Blastic plasmacytoid dendritic cell neoplasm (BPDCN) is a rare and aggressive hematodermic neoplasm usually involving the skin. In this retrospective case series, 10 cases of BPDCN were identified, 90% of which had skin involvement and exhibited predominantly violaceous nodules and/or bruise-like plaques. Skin lesions showed diffuse or nodular dermal-based infiltrates of intermediate sized blasts with a grenz zone. Tumor immunophenotyping was CD4(+), CD56(+), CD123(+) and CD303(+). The most frequently mutated genes according to targeted next-generation sequencing were TET2 (3/7) and NRAS (2/7). Multiagent chemotherapy (CT) was administered as first-line therapy, and a total of 5 patients underwent allogenic hematopoietic stem cell transplantation (allo-HSCT). Better outcomes were observed in younger patients and those treated with acute lymphoblastic leukemia (ALL)-like CT followed by allo-HSCT. This study shows the clinical range of cutaneous lesions of BPDCN. Despite the absence of a gold standard therapy, patients treated with myeloablative intensive regimens and allo-HSCT seem to have a more favorable prognosis.

A B-cell epigenetic signature defines three biologic subgroups of chronic lymphocytic leukemia with clinical impact.

Prospective identification of patients with chronic lymphocytic leukemia (CLL) destined to progress would greatly facilitate their clinical management. Recently, whole-genome DNA methylation analyses identified three clinicobiologic CLL subgroups with an epigenetic signature related to different normal B-cell counterparts. Here, we developed a clinically applicable method to identify these subgroups and to study their clinical relevance. Using a support vector machine approach, we built a prediction model using five epigenetic biomarkers that was able to classify CLL patients accurately into the three subgroups, namely naive B-cell-like, intermediate and memory B-cell-like CLL. DNA methylation was quantified by highly reproducible bisulfite pyrosequencing assays in two independent CLL series. In the initial series (n=211), the three subgroups showed differential levels of IGHV (immunoglobulin heavy-chain locus) mutation (P<0.001) and VH usage (P<0.03), as well as different clinical features and outcome in terms of time to first treatment (TTT) and overall survival (P<0.001). A multivariate Cox model showed that epigenetic classification was the strongest predictor of TTT (P<0.001) along with Binet stage (P<0.001). These findings were corroborated in a validation series (n=97). In this study, we developed a simple and robust method using epigenetic biomarkers to categorize CLLs into three subgroups with different clinicobiologic features and outcome.

The γ-secretase inhibitor PF-03084014 combined with fludarabine antagonizes migration, invasion and angiogenesis in NOTCH1-mutated CLL cells.

Targeting Notch signaling has emerged as a promising therapeutic strategy for chronic lymphocytic leukemia (CLL), especially for the poor prognostic subgroup of NOTCH1-mutated patients. Here, we report that the γ-secretase inhibitor PF-03084014 inhibits the constitutive Notch activation and induces selective apoptosis in CLL cells carrying NOTCH1 mutations. Combination of PF-03084014 with fludarabine has a synergistic antileukemic effect in primary NOTCH1-mutated CLL cells, even in the presence of the protective stroma. At transcriptional level, PF-03084014 plus fludarabine treatment induces the upregulation of the proapoptotic gene HRK and the downmodulation of MMP9, IL32 and RAC2 genes that are related to invasion and chemotaxis. PF-03084014 also overcomes fludarabine-mediated activation of nuclear factor-κB signaling. Moreover, this combination impairs angiogenesis and CXCL12-induced responses in NOTCH1-mutated CLL cells, in particular those related to tumoral migration and invasion. Importantly, all these collaborative effects are specific for NOTCH1 mutation and do not occur in unmutated cases. In conclusion, we provide evidence that Notch is a therapeutic target in CLL cases with NOTCH1-activating mutations, supporting the use of Notch pathway inhibitors in combination with chemotherapy as a promising approach for the treatment of these high-risk CLL patients.

Cell death targeting therapies in B lymphoid malignancies.

Programmed cell death, commonly associated with the term apoptosis, is an integrated intracellular program that plays a critical role in lymphoid tissue homeostasis. Alterations in this highly regulated process is a common feature of most lymphoid malignancies, thus facilitating tumor escape from traditional chemotherapeutic agents whose main endpoint is the induction of tumor cell death. In the last years, enormous progress has been made in understanding the deregulated signals that could lead to ineffective apoptosis in B lymphoid tumors. Consequently, several new strategies have been designed to modulate the key molecules of life-and-death decisions. Numerous novel approaches are being validated and some of them have progressed to clinical testing or have even been approved in a record time. In this review we will focus on current therapies that have demonstrated to trigger efficiently cell death in B lymphoid neoplasms, either by directly targeting the intracellular apoptotic machinery or by modulating different factors involved in its regulation.

BCL-2 phosphorylation modulates sensitivity to the BH3 mimetic GX15-070 (Obatoclax) and reduces its synergistic interaction with bortezomib in chronic lymphocytic leukemia cells.

Chronic lymphocytic leukemia (CLL) is a B-cell lymphoid neoplasm with deregulated apoptosis and overexpression of several antiapoptotic BCL-2 proteins. GX15-070/Obatoclax is a small-molecule BH3 mimetic compound that has shown activity against several hematologic malignancies and solid tumors. In the present work, we report that GX15-070 led to the disruption of BCL-2/BIM and MCL-1/BAK complexes in CLL cells, followed by the activation of the mitochondrial apoptotic pathway. CLL cells showed lower sensitivity to GX15-070 than primary mantle cell lymphoma (MCL) ones, in correlation with higher levels of phosphorylated BCL-2 at serine 70 residue (pBCL-2(Ser70)) in CLL cells. Decrease in BCL-2 phosphorylation by extracellular signal-regulated kinase (ERK)1/2 inhibition increased CLL sensitivity to GX15-070, while blocking BCL-2 dephosphorylation using a PP2A antagonist reduced the activity of this BH3 mimetic. GX15-070 activity was increased by cotreatment with the proteasome inhibitor bortezomib. However, as proteasome inhibition led to the accumulation of phosphorylated BCL-2, the degree of interaction between GX15-070 and bortezomib was regulated by basal pBCL-2(Ser70) levels. These results support the role of BCL-2 phosphorylation as a mechanism of resistance to BH3 mimetic compounds, and demonstrate that combination approaches including ERK inhibitors could enhance BH3 mimetics activity both alone or in combination with proteasome inhibitors.