Pro-apoptotic activity of α-bisabolol in preclinical models of primary human acute leukemia cells

<p>Abstract</p> <p>Background</p> <p>We previously demonstrated that the plant-derived agent α-bisabolol enters cells <it>via </it>lipid rafts, binds to the pro-apoptotic Bcl-2 family protein BID, and may induce apoptosis. Here we studied the activity of α-bisabolol in acute leukemia cells.</p> <p>Methods</p> <p>We tested <it>ex vivo </it>blasts from 42 acute leukemias (14 Philadelphia-negative and 14 Philadelphia-positive B acute lymphoid leukemias, Ph^-/Ph⁺B-ALL; 14 acute myeloid leukemias, AML) for their sensitivity to α-bisabolol in 24-hour dose-response assays. Concentrations and time were chosen based on CD34⁺, CD33⁺my and normal peripheral blood cell sensitivity to increasing α-bisabolol concentrations for up to 120 hours.</p> <p>Results</p> <p>A clustering analysis of the sensitivity over 24 hours identified three clusters. Cluster 1 (14 ± 5 μM α-bisabolol IC₅₀) included mainly Ph^-B-ALL cells. AML cells were split into cluster 2 and 3 (45 ± 7 and 65 ± 5 μM IC₅₀). Ph⁺B-ALL cells were scattered, but mainly grouped into cluster 2. All leukemias, including 3 imatinib-resistant cases, were eventually responsive, but a subset of B-ALL cells was fairly sensitive to low α-bisabolol concentrations. α-bisabolol acted as a pro-apoptotic agent <it>via </it>a direct damage to mitochondrial integrity, which was responsible for the decrease in NADH-supported state 3 respiration and the disruption of the mitochondrial membrane potential.</p> <p>Conclusion</p> <p>Our study provides the first evidence that α-bisabolol is a pro-apoptotic agent for primary human acute leukemia cells.</p

Haploidentical hematopoietic stem cell transplantation in a myelofibrosis patient with primary graft failure

The prognosis of patients affected by myelofibrosis (MF) is usually dismal and allogeneic hematopoietic stem cell transplantation (HSCT) remains the only cure. The number of HSCTs in MF patients has recently increased. However, a major obstacle is still represented by primary graft failure (PGF). Currently there are no definitive guidelines for the treatment of PGF and a second HSCT can be performed only when an allogeneic donor is rapidly available. Herein we report on a MF patient with PGF after an unrelated HSCT, who was rescued by a non-myeloablative, unmanipulated, haploidentical HSCT that resulted in persistent engraftment and bone-marrow fibrosis regression, but not in a long-term disease control. Based on this experience we briefly review the role of different conditioning regimens and hematopoietic stem cell sources in the setting of HSCT for MF patients with PGF. The role of haploidentical donors in MF patients lacking HLAmatched relatives is also discussed

Multiple large osteolytic lesions in a patient with systemic mastocytosis: a challenging diagnosis

Patients with advanced variants of Systemic Mastocytosis may develop destructive bone lesions when massive mast cell (MC) infiltrates are present. Finding of large osteolyses in indolent systemic mastocytosis, typically characterized by low MC burden, should prompt investigations for an alternative explanation

OFATUMUMAB AND LENALIDOMIDE PREFERENTIALLY INHIBIT B-CELL RECEPTOR SIGNALING IN CHRONIC LYMPHOCYTIC LEUKEMIA CELLS WITH MUTATED IGHV

Background. Lenalidomide has clinical activity in chronic lymphocytic leukemia (CLL) patients exerting pleiotropic activity on the immune system. The combination of lenalidomide with the anti-CD20 monoclonal antibody ofatumumab induces durable responses in patients with relapsed/refractory CLL. In addition to cell- and complement-mediated B-cell depletion induced by anti-CD20 antibodies and to immunomodulatory activity of lenalidomide, both drugs have been shown to directly inhibit survival and proliferation of malignant B cells. Signal transduction mediated by the B-cell receptor (BCR) promotes CLL survival and proliferation and is considered a key determinant of CLL clinical behavior and target for therapeutic interventions. However, the hypothesis that ofatumumab and lenalidomide could target BCR signal transduction has never been examined in CLL. Aims. In this study, we used phospho-specific flow cytometry to investigate the direct effects of lenalidomide and ofatumumab on BCR signaling in CLL cells from different prognostic groups of treatment-naive patients. Methods. The phosphorylation levels of four proteins downstream of the BCR signaling, namely SYK, ERK1/2, PLC-\u3b3, and NF-\u3baB p65, were analyzed at the single-cell level in 9 CLL cell samples treated in vitro with single-agent ofatumumab, single-agent lenalidomide or their combination, using phospho-specific flow cytometry. Phosphorylation was measured in the basal condition and following BCR stimulation with anti-IgM, resulting in overall 576 signal readouts. The repeated measures Anova with Dunnett's multiple comparison test was used to compare drug effects on protein phosphorylation. Results. Ofatumumab and lenalidomide induced different effects in ex-vivo CLL cells with different prognostic features as defined by the IGHV mutational status. In the IGHV-mutated (M) subset, treatment with ofatumumab, alone or in combination with lenalidomide, induced a significant reduction of SYK and ERK1/2 basal phosphorylation. Remarkably, in the same CLL group, lenalidomide significantly inhibited ERK1/2 basal phosphorylation. On the contrary, in the patient group defined by unmutated IGHV status (UM), treatment with ofatumumab and lenalidomide induced no significant changes in basal phosphorylation of BCR proteins. As expected, BCR stimulation with anti-IgM antibodies induced a signaling response in CLL cells that was statistically significant for ERK1/2, PLC-\u3b3, and NF-\u3baB p65. In the M subset, treatment with ofatumumab, alone or in combination with lenalidomide, significantly inhibited the anti-IgM signaling response of SYK and ERK1/2. Interestingly, lenalidomide significantly reduced the anti-IgM-induced signaling response of SYK. In contrast, in the UM CLL subset, ofatumumab and lenalidomide induced no significant changes in anti-IgM responses of BCR proteins. Conclusions. This study suggests that ofatumumab and lenalidomide can influence the BCR signaling in the basal state as well as under stimulation, with differential effects in distinct prognostic subsets of CLL. Although a study on a larger patient set is needed to extend and confirm these results, overall they indicate that ofatumumab and lenalidomide can inhibit BCR signaling in the M subset of CLL whilst have no significant effect in UM CLL, potentially contributing to the capacity of these drugs to differentially inhibit disease-progression in patients with CLL

Unmet needs in relapsed/refractory mantle cell lymphoma after failure of covalent Bruton's tyrosine kinase inhibitors: An Italian scenario

No abstract availabl

\u3b1-bisabolol is an effective proapoptotic agent against BCR-ABL+ cells in synergism with Imatinib and Nilotinib

We showed that \u3b1-bisabolol is active against primary acute leukemia cells, including BCR-ABL(+) acute lymphoblastic leukemias (ALL). Here we studied the activity of \u3b1-bisabolol against BCR-ABL(+) cells using 3 cell lines (K562, LAMA-84, CML-T1) and 10 primary BCR-ABL(+) ALL samples. We found that: (a) \u3b1-bisabolol was effective in reducing BCR-ABL(+) cell viabilty at concentrations ranging from 53 to 73 \ub5M; (b) \u3b1-bisabolol concentrations in BCR-ABL(+) cellular compartments were 4- to 12-fold higher than in normal cells, thus indicating a preferential intake in neoplastic cells; (c) \u3b1-bisabolol displayed a slight to strong synergism with the Tyrosine Kinase Inhibitors (TKI) imatinib and nilotinib: the combination of \u3b1-bisabolol+imatinib allowed a dose reduction of each compound up to 7.2 and 9.4-fold respectively, while the combination of \u3b1-bisabolol+nilotinib up to 6.7 and 5-fold respectively; (d) \u3b1-bisabolol-induced apoptosis was associated with loss of plasma membrane integrity, irreversible opening of mitochondrial transition pore, disruption of mitochondrial potential, inhibition of oxygen consumption and increase of intracellular reactive oxygen species. These data indicate \u3b1-bisabolol as a candidate for treatment of BCR-ABL(+) leukemias to overcome resistance to TKI alone and to target leukemic cells through BCR-ABL-independent pathways

Haploidentical hematopoietic stem cell transplantation in a myelofibrosis patient with primary graft failure

The prognosis of patients affected by myelofibrosis (MF) is usually dismal and allogeneic hematopoietic stem cell transplantation (HSCT) remains the only cure. The number of HSCTs in MF patients has recently increased. However, a major obstacle is still represented by primary graft failure (PGF). Currently there are no definitive guidelines for the treatment of PGF and a second HSCT can be performed only when an allogeneic donor is rapidly available. Herein we report on a MF patient with PGF after an unrelated HSCT, who was rescued by a non-myeloablative, unmanipulated, haploidentical HSCT that resulted in persistent engraftment and bone-marrow fibrosis regression, but not in a long-term disease control. Based on this experience we briefly review the role of different conditioning regimens and hematopoietic stem cell sources in the setting of HSCT for MF patients with PGF. The role of haploidentical donors in MF patients lacking HLAmatched relatives is also discussed