Abstract 4706: ABBV-075 exhibits robust in vitro and in vivo activities against the ABC and GCB subtypes of DLBCL

Diffuse Large B-Cell Lymphoma (DLBCL) consists of activated B-cell-like (ABC), germinal center B cell-like (GCB), and primary mediastinal B cell lymphoma (PMBL) subtypes. Among these, the ABC subtype of DLBCL often harbors mutations that cause abnormal NF-κB activation, which subsequently activates genes important for cell survival and disease progression in ABC DLBCL. The bromodomain and extraterminal domain (BET) protein BRD4 binds acetylated NF-κB and regulates NF-κB dependent transcription. Accordingly, targeting BET family proteins using small molecule inhibitors such as ABBV-075 might provide therapeutic benefit in ABC DLBCL by blocking the NF-κB pathway. In this study, we examined the activity of ABBV-075 in both the ABC and GCB subtypes of DLBCL. As expected, ABBV-075 diminished NF-κB reporter activity, down-regulated NF-κB target genes, inhibited proliferation and survival of ABC DLBCL cells in vitro, and delayed the growth of ABC DLBCL tumors in vivo. Interestingly, ABBV-075 also exhibited robust anti-proliferative activities in GCB DLBCL cells in vitro and inhibited the growth of GCB DLBCL tumors in vivo. Further characterization of the responses of GCB DLBCL cells to ABBV-075 indicated that ABBV-075 induced strong apoptosis in GCB DLBCL cells that are resistant to the Bcl-2 inhibitor venetoclax (ABT-199), but rarely in venetoclax-sensitive GCB DLBCL cell lines. Our results indicate that ABBV-075 could be active against both the ABC and GCB subtypes of DLBCL. The complementary activity of ABBV-075 and ABT-199 further suggests that ABBV-075 maybe an interesting option for ABT-199 resistant/refractory DLBCL patients.

Citation Format: Xiaoyu Lin, Xiaoli Huang, Aparna Sarthy, Terry Magoc, Daniel Albert, Lloyd Lam, Tamar Uziel, Xin Lu, Mai-Ha Bui, Emily Faivre, Denise Wilcox, Steven Elmore, Keith McDaniel, Warren Kati, Yu Shen. ABBV-075 exhibits robust in vitro and in vivo activities against the ABC and GCB subtypes of DLBCL. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 4706.

Abstract 4738: The BET family bromodomain inhibitor ABBV-075 is a promising therapeutic agent for acute myeloid leukemia and myelodysplastic syndrome

Small molecule inhibitors of the bromodomain and extraterminal domain (BET) proteins exhibit interesting activities in preclinical models of various cancer indications, and several of these inhibitors are currently under clinical investigation. ABBV-075 is a potent and selective BET family bromodomain inhibitor that recently entered Phase 1 studies. Upon characterizing cellular responses to BET inhibitors across a large panel of cancer cell lines, we identified AML/MDS as one of the few cancer indications where BET inhibitors triggered robust apoptosis in cancer cell lines and in patient-derived cancer cells. The induction of apoptosis by BET inhibitors in AML/MDS cells may be partly attributed to their abilities to down regulate Bcl-XL and Bcl-2, and combining BET inhibitors with the Bcl-2 inhibitor venetoclax (ABT-199) resulted in robust cytotoxicity in AML/MDS cells. ABBV-075 exhibited significant antitumor efficacy as a monotherapy in flank xenograft models of AML and MDS. Furthermore, combining low doses of ABBV-075 with the standard of care agent azacitidine in the SKM1 model led to significant tumor regression, and the combination regimen was better tolerated than BETi monotherapy at doses that produced a similar degree of therapeutic benefit. Expression profiling of SKM1 tumors from mice treated with the ABBV-075/azacitidine combination or each of these agents as monotherapies revealed that ABBV-075 and azacitidine regulated a common set of biologic pathways. The combination of ABBV-075/azacitidine led to a more robust impact on these common pathways, which may partially contribute to the enhanced efficacy of the ABBV-075/azacitidine combination in the SKM-1 model.

Citation Format: Mai H. Bui, Xiaoyu Lin, Xiaoli Huang, Leiming Li, Aparna Sarthy, Daniel Albert, Terry Magoc, Lloyd Lam, Paul Hessler, Tamar Uziel, Steven Elmore, Keith McDaniel, Warren Kati, Yu Shen. The BET family bromodomain inhibitor ABBV-075 is a promising therapeutic agent for acute myeloid leukemia and myelodysplastic syndrome. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 4738.

Venetoclax (ABT-199), a potent and selective BCL-2 inhibitor, is efficacious in NZB/WF1 mouse model of lupus nephritis and reduces human lymphocyte lifespan in vitro (BA4P.127)

Proteins in the BCL-2 family are key regulators of apoptosis, or programmed cell death. We have conducted studies to evaluate a highly potent and orally available BCL-2 selective inhibitor, venetoclax (ABT-199), for efficacy and mechanism of action in the lupus prone NZB/W F1 mouse model and in human cells in vitro. Venetoclax treatment dose-dependently reduced the incidence of severe proteinuria and prolonged survival compared to vehicle controls and attenuated glomerulonephritis, tubular dilatation, immune cell infiltrates and IgG deposition in the kidney. Venetoclax mediated a significant reduction in the numbers of splenic T cells but conferred a preferential reduction in select B cell subsets. Interestingly, venetoclax did not impair the number of CD138+ long-lived plasma cells in the bone marrow, which was consistent with unaltered circulating anti-dsDNA titers in these animals. Venetoclax efficacy also correlated with a dose -dependent reduction of lymphocytes in peripheral blood of NZB/WF1 mice. Consistent with these findings, human lymphocytes from both healthy donors and systemic lupus erythematosus (SLE) patients treated with venetoclax in vitro have reduced lifespan. Taken together, these data underscore the essential role of BCL-2 in the pathogenesis of lupus and support further exploration of selective BCL-2 inhibition in autoimmune diseases such as SLE/Lupus Nephritis. The design, study conduct, and financial support for this research were provided by AbbVie.

Profile measurements in the plasma edge of mega amp spherical tokamak using a ball pen probe

The ball pen probe (BPP) technique is used successfully to make profile measurements of plasma potential, electron temperature, and radial electric field on the Mega Amp Spherical Tokamak. The potential profile measured by the BPP is shown to significantly differ from the floating potential both in polarity and profile shape. By combining the BPP potential and the floating potential, the electron temperature can be measured, which is compared with the Thomson scattering (TS) diagnostic. Excellent agreement between the two diagnostics is obtained when secondary electron emission is accounted for in the floating potential. From the BPP profile, an estimate of the radial electric field is extracted which is shown to be of the order ∼1 kV/m and increases with plasma current. Corrections to the BPP measurement, constrained by the TS comparison, introduce uncertainty into the ER measurements. The uncertainty is most significant in the electric field well inside the separatrix. The electric field is used to estimate toroidal and poloidal rotation velocities from E × B motion. This paper further demonstrates the ability of the ball pen probe to make valuable and important measurements in the boundary plasma of a tokamak.

Divertor impurity injection using high voltage arcs for impurity transport studies on the Mega Amp Spherical Tokamak

The operation of next-generation fusion reactors will be significantly affected by impurity transport in the scrape-off layer (SOL). Current modelling efforts are restricted by a lack of detailed data on impurity transport in the SOL. In order to address this, a carbon injector has been designed and installed on the Mega Amp Spherical Tokamak (MAST). The injector creates short lived carbon plumes originating at the MAST divertor lasting less than 50 μs. High voltage capacitor banks are used to create a discharge across concentric carbon electrodes located in a probe mounted on the Divertor Science Facility in the MAST lower divertor. This results in a very short plume duration allowing observation of the evolution of the plume and precise localisation of the plume relative to the X-point on MAST. The emission from the carbon plume was imaged using fast visible cameras filtered in order to isolate the carbon II and carbon III emission lines centered around 514 nm and 465 nm.

Circulating biomarkers of cell death after treatment with the BH-3 mimetic ABT-737 in a preclinical model of small-cell lung cancer

PURPOSE

This study evaluated epithelial cell death ELISAs that measure circulating cytokeratin 18 in mice bearing small-cell lung cancer xenografts treated with a proapoptotic dose of the BH-3 mimetic ABT-737.

EXPERIMENTAL DESIGN

H146 tumor-bearing and non-H146 tumor-bearing severe combined immunodeficient (SCID)/bg mice were treated with ABT-737 or vehicle control. Plasma collected before and 2 to 360 hours after treatment was analyzed by M30 (caspase-cleaved cytokeratin 18) and M65 (intact and cleaved cytokeratin 18) ELISA. In parallel, tumors were interrogated for cleaved caspase-3 and cleaved cytokeratin 18 as biomarkers of apoptosis.

RESULTS

ABT-737-treated tumors regressed by 48 hours (P < 0.01) compared with controls, correlating with increased cleaved cytokeratin 18 (P < 0.01; 6 and 24 hours) and increased intact cytokeratin 18 (P < 0.01; 24 hours). Cleaved cytokeratin 18 levels decreased below baseline between 72 and 360 hours for ABT-737-treated and control mice whereas intact cytokeratin 18 decreased below the level of detection at 8 and 15 days in ABT-737-treated mice only. Apoptosis in tumors reflected changes in circulating cytokeratin 18 (cleaved caspase-3, P < 0.05 at 2 hours and P < 0.001 at 6, 12, and 24 hours; caspase-cleaved cytokeratin 18, P < 0.05 at 15 days, for drug treated versus controls).

CONCLUSIONS

ABT-737 caused tumor regression by apoptosis in H146 xenografts that mapped to a drug-specific, early increase in circulating cleaved cytokeratin 18 that subsequently declined. Circulating, intact cytokeratin 18 levels correlated with tumor burden. Cleaved caspase-3 and caspase-cleaved cytokeratin 18 in tumor correlated with treatment (P < 0.05, 2 hours; P < 0.001, 6, 12, and 24 hours; cleaved caspase-3, P < 0.05, 15 days; caspase-cleaved cytokeratin 18), indicating that events in plasma were tumor derived. These circulating biomarker data will be translated to clinical trials wherein serial tumor biopsies are rarely obtained.

The transduction of rat submandibular glands by an adenoviral vector carrying the human growth hormone gene is associated with limited and reversible changes at the infusion site

Adenoviral vectors have been shown to efficiently deliver exogenous genes to salivary glands and have therefore been investigated as tools for the treatment of human disease. The purpose of this study was to evaluate the response of F344 rats to intraductal infusion of the right submandibular salivary gland with an adenoviral vector encoding the gene for human growth hormone (AdCMVhGH). Co-administration of hydroxychloroquine (HCQ) was used to redirect the secretion of human growth hormone (hGH) from saliva into serum. This paper documents the findings of the pathology evaluation of this National Toxicology Program study. The right submandibular salivary gland (infusion site) was the primary target organ, with microscopic lesions characteristic of a mild to moderate insult observed at 3 days post infusion in vector exposed animals. These lesions were characterized by variable degrees of acute glandular inflammation, degeneration and necrosis, with more severe lesions in the higher dose groups. Rats at 28 days post infusion had milder inflammation, degeneration and necrosis compared to day 3 rats, with variable degrees of regeneration. In conclusion, the effects on the salivary glands are reversible as indicated by the milder inflammation and degeneration in the day 28 rats concomitant with mild to moderate regeneration. Therefore, the vector appears relatively innocuous with limited tissue toxicity. [The supplemental data referenced in this paper is not printed in this issue of Toxicologic Pathology. It is available as a downloadable file in the online edition of Toxicologic Pathology, 34(4). In order to access the full article online, you must have either an individual subscription or a member subscription accessed through www.toxpath.org.].

Toxicity and biodistribution of a first-generation recombinant adenoviral vector, in the presence of hydroxychloroquine, following retroductal delivery to a single rat submandibular gland

OBJECTIVE

We examined the toxicity and biodistribution associated with a single administration of a first-generation, serotype 5, adenoviral vector encoding human growth hormone (hGH; AdCMVhGH) to a single rat submandibular gland in the presence of hydroxychloroquine (HCQ). Previously, we showed that hGH is primarily secreted into saliva (approximately ninefold serum level) when expressed as a transgene in salivary glands (e.g. Baum et al, 1999), but administration of HCQ substantially increases the hGH levels secreted into the bloodstream (Hoque et al, 2001). A potential application of this observation is for patients with adult hGH deficiency.

METHODS

Six groups of male and female adult rats (n = 12 each) were studied, with zero to 1.5 x 10(11) particles of AdCMVhGH, +/-HCQ, administered retroductally. Multiple clinical and pathological parameters, as well as vector tissue distribution, were assessed.

RESULTS

All animals survived until the scheduled day of sacrifice, and essentially no untoward events were observed clinically or at gross necropsy. We observed no vector-related effects on clinical hematology evaluations and a single, transient significant change on clinical chemistry evaluations (increased serum globulin levels). Three days after AdCMVhGH administration, the vector distributed to all tissues analyzed with the exception of gonads and heart. By day 29, most organs, other than the targeted and contralateral submandibular glands, were negative for the presence of vector. On day 3, none of the animals tested positive for the presence of replication competent adenovirus in either their blood or saliva.

CONCLUSION

Salivary gland delivery of AdCMVhGH +/-HCQ appears associated with limited toxicity in rats.

Single-particle tracking of oriC-GFP fluorescent spots during chromosome segregation in Escherichia coli

DNA regions close to the origin of replication were visualized by the green fluorescent protein (GFP)-Lac repressor/lac operator system. The number of oriC-GFP fluorescent spots per cell and per nucleoid in batch-cultured cells corresponded to the theoretical DNA replication pattern. A similar pattern was observed in cells growing on microscope slides used for time-lapse experiments. The trajectories of 124 oriC-GFP spots were monitored by time-lapse microscopy of 31 cells at time intervals of 1, 2, and 3 min. Spot positions were determined along the short and long axis of cells. The lengthwise movement of spots was corrected for cell elongation. The step sizes of the spots showed a Gaussian distribution with a standard deviation of approximately 110 nm. Plots of the mean square displacement versus time indicated a free diffusion regime for spot movement along the long axis of the cell, with a diffusion coefficient of 4.3+/-2.6x10(-5) microm2/s. Spot movement along the short axis showed confinement in a region of the diameter of the nucleoid ( approximately 800 nm) with an effective diffusion coefficient of 2.9+/-1.7x10(-5) microm2/s. Confidence levels for the mean square displacement analysis were obtained from numerical simulations. We conclude from the analysis that within the experimental accuracy--the limits of which are indicated and discussed--there is no evidence that spot segregation requires any other mechanism than that of cell (length) growth.

Visualization of mitochondria in cardiomyocytes by simultaneous harmonic generation and fluorescence microscopy

The simultaneous detection of third harmonic (THG), and multiphoton excitation fluorescence (MPF) or second harmonic (SHG) from the same focal volume has led us to the development of a nonlinear multimodal microscopic biological imaging tool. The multimodal microscope has been applied for imaging of isolated live cardiomyocytes, and investigation of structural origin of the THG and SHG signals has been performed. By employing the different image contrast mechanisms, differentiation of structures inside a single live adult rat cardiomyocyte has been achieved. Based on structural crosscorrelation image analysis between NAD(P)H fluorescence and THG, and morphology of cardiomyocytes we were able to assign large part of the structure revealed by THG to the mitochondria. The crosscorrelation of THG with fluorescence of tetramethylrhodamine methyl ester (TMRM) labeled cardiomyocytes confirmed the mitochondrial origin of THG. The SHG generated structures were anticorrelated with THG and possessed the characteristic pattern of the myofibrils in the myocyte in accordance with the literature. Possible visualization of mitochondria with THG microscopy appeared due to enhancement of the third harmonic by multilayer arrangement of cristae.

Characterization of the cytoplasmic filament protein gene (cfpA) of Treponema pallidum subsp. pallidum

Treponema pallidum and other members of the genera Treponema, Spirochaeta, and Leptonema contain multiple cytoplasmic filaments that run the length of the organism just underneath the cytoplasmic membrane. These cytoplasmic filaments have a ribbon-like profile and consist of a major cytoplasmic filament protein subunit (CfpA, formerly called TpN83) with a relative molecular weight of approximately 80,000. Degenerate DNA primers based on N-terminal and CNBr cleavage fragment amino acid sequences of T. pallidum subsp. pallidum (Nichols) CfpA were utilized to amplify a fragment of the encoding gene (cfpA). A 6.8-kb EcoRI fragment containing all but the 5' end of cfpA was identified by hybridization with the resulting PCR product and cloned into Lambda ZAP II. The 5' region was obtained by inverse PCR, and the complete gene sequence was determined. The cfpA sequence contained a 2,034-nucleotide coding region, a putative promoter with consensus sequences (5'-TTTACA-3' for -35 and 5'-TACAAT-3' for -10) similar to the sigma70 recognition sequence of Escherichia coli and other organisms, and a putative ribosome-binding site (5'-AGGAG-3'). The deduced amino acid sequence of CfpA indicated a protein of 678 residues with a calculated molecular mass of 78.5 kDa and an estimated pI of 6.15. No significant homology to known proteins or structural motifs was found among known prokaryotic or eukaryotic sequences. Expression of a LacZ-CfpA fusion protein in E. coli was detrimental to survival and growth of the host strain and resulted in the formation of short, irregular filaments suggestive of partial self-assembly of CfpA. The cytoplasmic filaments of T. pallidum and other spirochetes appear to represent a unique form of prokaryotic intracytoplasmic inclusions.

Alcoholic seizures: intellectual and neuropsychological sequelae

Alcoholics who experienced withdrawal seizures performed comparably to those who did not suffer seizures on intellectual and neuropsychological tests. Both groups, however, exhibited a number of impairments. The hypothesis that the withdrawal seizure is indicative of alcoholism severity and can serve as a marker for extent of neurological disturbance was not supported.