ALBERT

Beschreibung: Background: The highly unfavorable outcome of patients with recurrent HL, who progress after stem cell transplantation or are ineligible for such procedure make the development of new active agents an impellent medical need in this clinical setting. EDO-S101 is fusion molecule combining the DNA damaging effects of bendamustine (BDM) with the pan-histone deacetylase (HDAC) inhibitor, vorinostat. Given that BDM and HDAC inhibitors are active agents in recurrent HL we investigated the preclinical activity of EDO-S101 in this malignancy. Methods: We assessed the patterns of EDO-S101 cytotoxicity (0.39 to 50 µmol/L) in a panel of HL-derived cell lines (L1236, L428, KMH2, HDLM2, L540) and its regulatory effects on genes involved in DNA-damage/repair response, apoptosis and cell cycle checkpoints. As a further model we exploited an L1236 cell clone (R100) selected for resistance (R) to BDM through continuous exposure to increasing concentrations of the agent. R100 cells display a growth pattern indistinguishable from parental L1236 cells when cultured in the presence of BDM (100 µmol/L). Clonal identity of R100 cells with parental L1236 was confirmed by sequencing of V3-21 (FR2/FR3) and JH3-JH4 Ig DNA regions. Results: EDO-S101 induced a significant time- and dose-dependent inhibition of growth and survival in all HL cell lines. L1236 cells displayed the highest sensitivity to the agent with an IC50, at 48 hrs, of 1.88 µmol/L, as opposed to KMH2, L428, L540 and HDLM2 cells with IC50 of 2.06, 2.53, 2.26 and 16.2 µmol/L, respectively. These values were about 10-fold lower than the IC50 of BDM in the same cell lines. While exposure of L1236 cells to EDO-S101 caused cell accumulation in S-phase, qRT-PCR disclosed that cell death was mainly dependent on triggering of apoptosis, as shown by the early (24 hrs) and sustained (48 hrs) upregulation of NOXA, p21 and p27 genes. Data were confirmed by the significant increase (〉150%) of Annexin V-expressing L1236 cells. In contrast, expression levels of PLK1, AKA and cyclin B1 genes remained unchanged or were increased. This excluded induction of the mitotic catastrophe (MC) as a major determinant of cytotoxic activity for EDO-S101 in L1236 cells. Exposure to EDO-S101 induced a strong DNA stress/repair response as shown by the activation of pATR/pATM and increase of the downstream DNA damage checkpoint proteins pCHK1-/-2 and CCNB1, along with the upregulation of the EXO1 gene. Most intriguingly, BDM-resistant L1236 cells (R100) were highly sensitive to EDO-S101, with an IC50 of only 4.56 µmol/L, but less responsive to vorinostat (IC50: 6.17 µmol/L) than parental L1236 cells (IC50: 0.58 µmol/L). Differently from native cells, EDO-S101 induced a late downregulation of transcripts for PLK1 and AKA genes and of cyclin B1 gene and protein in R100 cells, along with the early induction of NOXA and p21, but not p27 genes. In both L1236 and R100 cells, expression of MC-genes was unaffected by exposure to vorinostat. This suggests a more complex mechanism for EDO-S101 in BDM-resistant HL cells involving activation of the both apoptotic and MC pathways. Notably, we documented that EDO-S101 corrected the constitutive ATM/ATR unbalance of R100 cells by triggering the early (24 hrs) upregulation of ATR and a late (48 hrs) downregulation of ATM transcripts and proteins, along with increased levels of EXO1 and MGMT at 24 hrs. Vorinostat induced a similar effect. Finally, while baseline expression levels of HDAC isoforms were comparable among HL cell lines, EDO-S101 caused a significant (〉40%) late downregulation of transcripts for all HDAC isoforms (HDAC-1 to -8) in R100 cells but only of HDAC-6 in native L1236. This pattern diverged from results obtained in both L1236, i.e. increase of all HDAC isoform transcripts except HDAC-6, and R100 cells, i.e. upregulation of all isoforms and reduction of HDAC-6, with vorinostat and BDM as single agents. Conclusions: We have described for the first time that EDO-S101 is effective in preclinical models of HL including cells resistant to BDM. The combined functions of in one molecule of a bifunctional alkylator and panHDAC inhibitor confer this agent unique antitumor property different from both of its single drug components. Following a strong DNA damage response, triggering of apoptosis and/or MC may take place in HL cells according to their sensitivity status to BDM. A phase 1/2 study in recurrent HL, including patients pretreated with BDM, is next to be launched. Disclosures Mehrling: 4Mundipharma-EDO GmbH, Basel, Switzerland: Employment. Pinto:Takeda, Celgene, Roche, TEVA: Honoraria; Takeda: Research Funding.

Beschreibung: Chronic Lymphocytic Leukemia (CLL) represents the most frequent adult leukemia, and remains incurable with current standard therapies. Natural Killer (NK) cell count is predictive of CLL disease progression and their dysfunction in mediating cytokine release and direct or antibody dependent cellular cytotoxicity (ADCC) against CLL B-cells is well documented. Detailed mechanistic insight into the etiology of NK-cell dysfunction in CLL patients is currently lacking. CLL B-cells overexpress HLA-E, the natural ligand for heterodimer CD94/NKG2A receptor complex that is expressed on the surface of NK cells, and this interaction suppresses NK cell activation. While NKG2A/CD94/HLA-E interaction is known to assist NK cells in recognizing "self", tumor cells utilize this mechanism to evade effector cell killing. Utilizing a novel anti-NKG2A monoclonal blocking antibody (mab) we explored the in vitro preclinical activity of targeting the NKG2A receptor, and the NKG2A/HLA-E interaction as a mechanism of tumor evasion in patients with CLL. We hypothesized that limiting the interaction of HLA-E/NKG2A will reverse NK cell anergy and result in increased direct cytotoxicity of CLL cells. Our results confirm the over expression of HLA-E on CLL B-cells and demonstrate NKG2A expression on CD16+ NK cells from CLL patients. Next, we examined the effect of anti-NKG2A mab on NK cell direct cytotoxicity. Treatment of NK cells, from both healthy donor and CLL patients, with anti-NKG2A mab increased direct cytotoxicity over isotype control on targets at various effector to target ratios of 25:1 (54% vs. 46%, p〈 0.05, n= 12), 12:1 (43% vs. 35%, p

Beschreibung: Ligation of the B-cell receptor (BCR) results in activation of intracellular signaling as well as internalization and processing of ligand/receptor complexes. BCR responsiveness has been shown to vary markedly between patients with chronic lymphocytic leukaemia (CLL) and is linked to prognosis. Despite the central importance of BCR signaling in CLL and the efficacy of drugs that block this pathway, relatively little is known about the capacity of CLL B-cells to internalize ligands that bind to the BCR. In the present study we investigated whether, like normal B-cells, CLL cells can internalize their BCR following stimulation. First, we assessed to what extent this varies between various prognostic subgroups. Second, given that BCR signaling is thought to be more pronounced within lymphoid tissue, we investigated whether internalization varies between different anatomic sites of the same individual. Finally, we examined the effect of agents that inhibit BCR function by comparing BCR expression and internalization in a cohort of patient before and during therapy with Bruton's tyrosine kinase inhibitors (BTKi). BCR internalization was assessed in two ways. First, we used a pH sensitive dye linked to agonistic anti-IgM (pHrodo-αIgM) to detect the uptake and retention of ligand/receptor complexes in acidified endosomes. Second, BCR internalization was assessed directly by measuring the rate of disappearance of surface IgM following ligation by agonistic anti-IgM. An increase in the percentage of cells showing pHrodo fluorescence above control was detected in all CLL cases studied (mean percentage pHrodo-αIgM uptake = 30.2±2.5%, p

Beschreibung: Background: Given the consistent antitumor activity and favorable toxicity profile in heavily pretreated patients, BDM represents a suitable platform for combination with target-based agents in the setting of recurrent HL. The anti-CD30 antibody-monomethyl auristatin E (MMAE) conjugate brentuximab vedotin (BV) appears a most valuable candidate by coupling an impressive clinical activity with the lack of serious overlapping toxicities with BDM. While the combination of BDM and BV is being evaluated in Phase II studies, no information is available as to possible mechanisms through which BDM may regulate the antitumor efficacy of BV towards HL cells. Methods: We evaluated the effects of acute and extended exposure to BDM on CD30 expression and sensitivity to the cytotoxic activity BV in the HL cell line L1236. Cells were cultured in the presence of BDM at its IC50 for different time points of acute exposure. Through continuous exposure to increasing concentrations (25.0, 50.0, 75.0, 100 micromol/L) of BDM, we then performed a serial in vitro selection for BDM-resistant (R) L1236 cell clones and determined their CD30 expression by flow cytometry, qRT-PCR, and Western analysis. Results: Acute exposure to BDM (48 to 72 hrs) of L1236 cells led to a sizeable upregulation of CD30 as shown by flow cytometry. This effect was unsustained since CD30 intensity returned to baseline levels upon culturing in BDM-free medium for one week. Expression of other surface antigens, i.e. HLA-DR, was unaffected by BDM while acute exposure to doxorubicin and other cytotoxic drugs did not modify the CD30 expression. We established four L1236-derived cell clones (R25, R50, R75 and R100) able to proliferate across the different concentrations of BDM with growth/viability curves superimposable to native cells. Clonal identity among clones and with parental cells was confirmed by sequencing of V3-21 (FR2/FR3) and JH3-JH4 Ig DNA regions. All R-clones displayed an up to 900% increase in CD30 median fluorescence intensity, relative to native L1236 cells (Figure 1A). The sustained CD30 upregulation was confirmed by qRT-PCR and Western blotting since R-clones expressed up to 10-fold higher levels of CD30-specific mRNA and CD30-specific 120 kDa components as compared to parental cells. To rule out a general upregulation of surface molecules as a result of the chronic exposure to BDM we evaluated the expression of other surface antigens. As opposed to CD30, HLA-DR and PDL-1 relative transcript levels and cell surface expression were significantly reduced in R-cells. Intriguingly, BDM-induced CD30 upregulation was specific to L1236 cells since extended exposure to BDM did not modify expression levels of CD30 in other lymphoma cell types (SUDHL1, JEKO). BDM-induced CD30 overexpression significantly enhanced the sensitivity of HL cells to the cytotoxic effects of BV. MTS assay showed the IC50 of R100 cells to BV shifted to 0.21 ± 0.06 mcg/mL (48 hrs) and 0.19 ± 0.05 mcg/mL (72 hrs) vs. 3.16 ± 0.75 mcg/mL (48 hrs) and 3.87 ± 0.68 mcg/mL (72 hrs) of parental cells, a 15- and 20-fold increase, respectively (p

Beschreibung: Background: Autologous stem cell transplantation (ASCT) has been widely used in the treatment of hematological malignancies over the last two decades. Despite its broad use, some characteristics that might influence engraftment have not been exhaustively investigated, particularly graft purity with respect to contamination by platelets (PLTS) and White Blood Cells (WBC). Here we report collection characteristics and engraftment kinetics of a single Center consecutive series of 510ASCTs. Methods: We retrospectively collected clinical records of patients who underwentleucapheresis procedures (LA; followed or not byASCT) at our Institution over 16 years (2000-2016): 290 patients collected peripheral blood stem cells (PBSC) (80 Multiple Myeloma MM, 133 Non Hodgkin Lymphoma NHL, 22 Hodgkin Lymphoma HL, 32 Acute Myeloid Leukemia AML, 23 other diseases) for a total of 481LAs. Mobilizing regimens are described in Table 1. We considered the number of harvested CD34+ cells *106/kg the first day of LA. Data on 458 patients (191 MM, 190 NHL, 45 HL, 19 AML and 13 other diseases) for a total of 510 ASCTs were acquired. The impact on engraftment kinetics of conditioning chemotherapies, amount of infused CD34+ cells and WBC/PLTS graft contamination were analyzed. Absolute neutrophil count (ANC) engraftment was defined as the duration of neutropenia (from day 0 to the first of 3 consecutive days of ANC〉500/ul post ASCT). Results: Regarding CD34+ cell collection, no impact of mobilizing regimens and WBC count during LA was observed. On the other hand, we observed a difference in the number of total CD34+ cells collected among different diagnoses: the median overall collection was 7.2 (0.65-64.06)*106/kg CD34+ cells for NHL patients, 5.66 (0.71-23.31)*106/kg for MM patients, 6.15 (0.51-23.24) *106/kg for HL patients and 3.56 (0.64-20.3)*106/kg for AML patients) (p = 0.001). Considering CD34+ cells/kg harvested on the first day of LA, 59.2% of NHL and HL, 57.5% of MM patients and 34% of AML patients harvested ³ 5*106/Kg CD34+ cells. Of note, among AML patients, 40.6% collected less than 2.5*106/kg. The differences were statistically significant (p = 0.003) (Tab. 2). Moreover, an inverse correlation between collected CD34+ cells and age was shown (p = 0.001) (Fig.1). ANC recovery after ASCTwas not influenced by conditioning regimen whereas diagnosis impacted on the duration of neutropenia (AML patients displayed a longer aplasia, p 〈 0.01). We observed that the median days with ANC5.3*10^6/kg, 3.5-5.3*10^6/kg and