PI3K signaling promotes formation of lipid-laden foamy macrophages at the spinal cord injury site

After spinal cord injury (SCI), infiltrating macrophages undergo excessive phagocytosis of myelin and cellular debris, forming lipid-laden foamy macrophages. To understand their role in the cellular pathology of SCI, investigation of the foamy macrophage phenotype in vitro revealed a pro-inflammatory profile, increased reactive oxygen species (ROS) production, and mitochondrial dysfunction. Bioinformatic analysis identified PI3K as a regulator of inflammation in foamy macrophages, and inhibition of this pathway decreased their lipid content, inflammatory cytokines, and ROS production. Macrophage-specific inhibition of PI3K using liposomes significantly decreased foamy macrophages at the injury site after a mid-thoracic contusive SCI in mice. RNA sequencing and in vitro analysis of foamy macrophages revealed increased autophagy and decreased phagocytosis after PI3K inhibition as potential mechanisms for reduced lipid accumulation. Together, our data suggest that the formation of pro-inflammatory foamy macrophages after SCI is due to the activation of PI3K signaling, which increases phagocytosis and decreases autophagy.

Empagliflozin reduces podocyte lipotoxicity in experimental Alport syndrome

Sodium-glucose cotransporter-2 inhibitors (SGLT2i) are anti-hyperglycemic agents that prevent glucose reabsorption in proximal tubular cells. SGLT2i improves renal outcomes in both diabetic and non-diabetic patients, indicating it may have beneficial effects beyond glycemic control. Here, we demonstrate that SGLT2i affects energy metabolism and podocyte lipotoxicity in experimental Alport syndrome (AS). In vitro, we found that the SGLT2 protein was expressed in human and mouse podocytes to a similar extent in tubular cells. Newly established immortalized podocytes from Col4a3 knockout mice (AS podocytes) accumulate lipid droplets along with increased apoptosis when compared to wild-type podocytes. Treatment with SGLT2i empagliflozin reduces lipid droplet accumulation and apoptosis in AS podocytes. Empagliflozin inhibits the utilization of glucose/pyruvate as a metabolic substrate in AS podocytes but not in AS tubular cells. In vivo, we demonstrate that empagliflozin reduces albuminuria and prolongs the survival of AS mice. Empagliflozin-treated AS mice show decreased serum blood urea nitrogen and creatinine levels in association with reduced triglyceride and cholesterol ester content in kidney cortices when compared to AS mice. Lipid accumulation in kidney cortices correlates with a decline in renal function. In summary, empagliflozin reduces podocyte lipotoxicity and improves kidney function in experimental AS in association with the energy substrates switch from glucose to fatty acids in podocytes.

A Robust Phenotypic Screening Assay Utilizing Human Podocytes to Identify Agents that Modulate Lipid Droplets

Lipid droplets (LDs), initially thought to be mere lipid storage structures, are highly dynamic organelles with complex functions that control cell fate and behavior. In recent years, their relevance as therapeutic targets for a wide array of human diseases has been well established. Consequently, efforts to develop tools to study them have intensified, including assays that can accurately track LD levels in clinically relevant cell-based models. We previously reported that LD accumulation destines podocytes for lipotoxicity and cell death in renal diseases of metabolic and nonmetabolic origin. We also showed that LD accumulation in those cells serves as both a marker for disease progression and as a therapeutic target. Here, we describe a robust phenotypic screening method, using differentiated human podocytes, for identifying small-molecule compounds that rescue podocytes from LD accumulation and lipotoxicity under cellular stress. Major assay advances include 1) the use of a solvatochromic dye to improve LD staining, reduce background noise, and improve detection accuracy, 2) use of confocal imaging to reduce vertical overlap of LDs and enable accurate counting, 3) combining membrane and cytoskeleton stains to improve cell segmentation in confocal mode, and 4) use of an optimized spot detection algorithm that requires minimal configuration per individual run. The assay is robust and yields a Z-factor that is consistently >0.5.

Compounds co-targeting kinases in axon regulatory pathways promote regeneration and behavioral recovery after spinal cord injury in mice

Recovery from spinal cord injury (SCI) and other central nervous system (CNS) trauma is hampered by limits on axonal regeneration in the CNS. Regeneration is restricted by the lack of neuron-intrinsic regenerative capacity and by the repressive microenvironment confronting damaged axons. To address this challenge, we have developed a therapeutic strategy that co-targets kinases involved in both extrinsic and intrinsic regulatory pathways. Prior work identified a kinase inhibitor (RO48) with advantageous polypharmacology (co-inhibition of targets including ROCK2 and S6K1), which promoted CNS axon growth in vitro and corticospinal tract (CST) sprouting in a mouse pyramidotomy model. We now show that RO48 promotes neurite growth from sensory neurons and a variety of CNS neurons in vitro, and promotes CST sprouting and/or regeneration in multiple mouse models of spinal cord injury. Notably, these in vivo effects of RO48 were seen in several independent experimental series performed in distinct laboratories at different times. Finally, in a cervical dorsal hemisection model, RO48 not only promoted growth of CST axons beyond the lesion, but also improved behavioral recovery in the rotarod, gridwalk, and pellet retrieval tasks. Our results provide strong evidence for RO48 as an effective compound to promote axon growth and regeneration. Further, they point to strategies for increasing robustness of interventions in pre-clinical models.

Adaptive and maladaptive roles of lipid droplets in health and disease

Advances in the understanding of lipid droplet biology have revealed essential roles for these organelles in mediating proper cellular homeostasis and stress response. Lipid droplets were initially thought to play a passive role in energy storage. However, recent studies demonstrate that they have substantially broader functions, including protection from reactive oxygen species, endoplasmic reticulum stress, and lipotoxicity. Dysregulation of lipid droplet homeostasis is associated with various pathologies spanning neurological, metabolic, cardiovascular, oncological, and renal diseases. This review provides an overview of the current understanding of lipid droplet biology in both health and disease.

Phenotypic Screening Following Transcriptomic Deconvolution to Identify Transcription Factors Mediating Axon Growth Induced by a Kinase Inhibitor

After injury to the central nervous system (CNS), both neuron-intrinsic limitations on regenerative responses and inhibitory factors in the injured CNS environment restrict regenerative axon growth. Instances of successful axon regrowth offer opportunities to identify features that differentiate these situations from that of the normal adult CNS. One such opportunity is provided by the kinase inhibitor RO48, which dramatically enhances neurite outgrowth of neurons in vitro and substantially increased contralateral sprouting of corticospinal tract neurons when infused intraventricularly following unilateral pyramidotomy. The authors present here a transcriptomic deconvolution of RO48-associated axon growth, with the goal of identifying transcriptional regulators associated with axon growth in the CNS. Through the use of RNA sequencing (RNA-seq) and transcription factor binding site enrichment analysis, the authors identified a list of transcription factors putatively driving differential gene expression during RO48-induced neurite outgrowth of rat hippocampal neurons in vitro. The 82 transcription factor motifs identified in this way included some with known association to axon growth regulation, such as Jun, Klf4, Myc, Atf4, Stat3, and Nfatc2, and many with no known association to axon growth. A phenotypic loss-of-function screen was carried out to evaluate these transcription factors for their roles in neurite outgrowth; this screen identified several potential outgrowth regulators. Subsequent validation suggests that the Forkhead box (Fox) family transcription factor Foxp2 restricts neurite outgrowth, while FoxO subfamily members Foxo1 and Foxo3a promote neurite outgrowth. The authors' combined transcriptomic-phenotypic screening strategy therefore allowed identification of novel transcriptional regulators of neurite outgrowth downstream of a multitarget kinase inhibitor.

A novel strategy for combination of clofarabine and pictilisib is synergistic in gastric cancer

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Drug sensitivity testing identified novel drugs like clofarabine effective in treating gastric cancer.

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mRNA sequencing can be used to identify agents with synergistic activity to a reference compound.

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Pictilisib sensitizes gastric cancer to clofarabine treatment through AKT inhibition.

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The combination of clofarabine and pictilisib inhibits tumor growth in cell lines and PDX models.

Gastric cancer (GC) is frequently characterized by resistance to standard chemotherapeutic regimens and poor clinical outcomes. We aimed to identify a novel therapeutic approach using drug sensitivity testing (DST) and our computational SynerySeq pipeline. DST of GC cell lines was performed with a library of 215 Federal Drug Administration (FDA) approved compounds and identified clofarabine as a potential therapeutic agent. RNA-sequencing (RNAseq) of clofarabine treated GC cells was analyzed according to our SynergySeq pipeline and identified pictilisib as a potential synergistic agent. Clonogenic survival and Annexin V assays demonstrated increased cell death with clofarabine and pictilisib combination treatment (P<0.01). The combination induced double strand breaks (DSB) as indicated by phosphorylated H2A histone family member X (γH2AX) immunofluorescence and western blot analysis (P<0.01). Pictilisib treatment inhibited the protein kinase B (AKT) cell survival pathway and promoted a pro-apoptotic phenotype as evidenced by quantitative real time polymerase chain reaction (qRT-PCR) analysis of the B-cell lymphoma 2 (BCL2) protein family members (P<0.01). Patient derived xenograft (PDX) data confirmed that the combination is more effective in abrogating tumor growth with prolonged survival than single-agent treatment (P<0.01). The novel combination of clofarabine and pictilisib in GC promotes DNA damage and inhibits key cell survival pathways to induce cell death beyond single-agent treatment.

Discoidin domain receptor 1 activation links extracellular matrix to podocyte lipotoxicity in Alport syndrome

Background

Discoidin domain receptor 1 (DDR1) is a receptor tyrosine kinase that is activated by collagens that is involved in the pathogenesis of fibrotic disorders. Interestingly, de novo production of the collagen type I (Col I) has been observed in Col4a3 knockout mice, a mouse model of Alport Syndrome (AS mice). Deletion of the DDR1 in AS mice was shown to improve survival and renal function. However, the mechanisms driving DDR1-dependent fibrosis remain largely unknown.

Methods

Podocyte pDDR1 levels, Collagen and cluster of differentiation 36 (CD36) expression was analyzed by Real-time PCR and Western blot. Lipid droplet accumulation and content was determined using Bodipy staining and enzymatic analysis. CD36 and DDR1 interaction was determined by co-immunoprecipitation. Creatinine, BUN, albuminuria, lipid content, and histological and morphological assessment of kidneys harvested from AS mice treated with Ezetimibe and/or Ramipril or vehicle was performed.

Findings

We demonstrate that Col I-mediated DDR1 activation induces CD36-mediated podocyte lipotoxic injury. We show that Ezetimibe interferes with the CD36/DDR1 interaction in vitro and prevents lipotoxicity in AS mice thus preserving renal function similarly to ramipril.

Interpretation

Our study suggests that Col I/DDR1-mediated lipotoxicity contributes to renal failure in AS and that targeting this pathway may represent a new therapeutic strategy for patients with AS and with chronic kidney diseases (CKD) associated with Col4 mutations.

Funding

This study is supported by the NIH grants R01DK117599, R01DK104753, R01CA227493, U54DK083912, UM1DK100846, U01DK116101, UL1TR000460 (Miami Clinical Translational Science Institute, National Center for Advancing Translational Sciences and the National Institute on Minority Health and Health Disparities), F32DK115109, Hoffmann-La Roche and Alport Syndrome Foundation.

Sterol-O-acyltransferase-1 has a role in kidney disease associated with diabetes and Alport syndrome

Defective cholesterol metabolism primarily linked to reduced ATP-binding cassette transporter A1 (ABCA1) expression is closely associated with the pathogenesis and progression of kidney diseases, including diabetic kidney disease and Alport Syndrome. However, whether the accumulation of free or esterified cholesterol contributes to progression in kidney disease remains unclear. Here, we demonstrate that inhibition of sterol-O-acyltransferase-1 (SOAT1), the enzyme at the endoplasmic reticulum that converts free cholesterol to cholesterol esters, which are then stored in lipid droplets, effectively reduced cholesterol ester and lipid droplet formation in human podocytes. Furthermore, we found that inhibition of SOAT1 in podocytes reduced lipotoxicity-mediated podocyte injury in diabetic kidney disease and Alport Syndrome in association with increased ABCA1 expression and ABCA1-mediated cholesterol efflux. In vivo, Soat1 deficient mice did not develop albuminuria or mesangial expansion at 10-12 months of age. However, Soat1 deficiency/inhibition in experimental models of diabetic kidney disease and Alport Syndrome reduced cholesterol ester content in kidney cortices and protected from disease progression. Thus, targeting SOAT1-mediated cholesterol metabolism may represent a new therapeutic strategy to treat kidney disease in patients with diabetic kidney disease and Alport Syndrome, like that suggested for Alzheimer's disease and cancer treatments.

Ovarian Cancer Treatment Stratification Using Ex Vivo Drug Sensitivity Testing

BACKGROUND

Treatment options for patients with platinum-resistant ovarian cancer are generally palliative in nature and rarely have realistic potential to be curative. Because many patients with recurrent ovarian cancer receive aggressive chemotherapy for prolonged periods, sometimes continuously, therapy-related toxicities are a major factor in treatment decisions. The use of ex vivo drug sensitivity screens has the potential to improve the treatment of patients with platinum-resistant ovarian cancer by providing personalized treatment plans and thus reducing toxicity from unproductive therapy attempts.

MATERIALS AND METHODS

We evaluated the treatment responses of a set of six early-passage patient-derived ovarian cancer cell lines towards a set of 30 Food and Drug Administration-approved chemotherapy drugs using drug-sensitivity testing.

RESULTS

We observed a wide range of treatment responses of the cell lines. While most compounds displayed vastly different treatment responses between cell lines, we found that some compounds such as docetaxel and cephalomannine reduced cell survival of all cell lines.

CONCLUSION

We propose that ex vivo drug-sensitivity screening holds the potential to greatly improve patient outcomes, especially in a population where multiple continuous treatments are not an option due to advanced disease, rapid disease progression, age or poor overall health. This approach may also be useful to identify potential novel therapeutics for patients with ovarian cancer.

Phenotypic Screening Combined with Machine Learning for Efficient Identification of Breast Cancer-Selective Therapeutic Targets

The lack of functional understanding of most mutations in cancer, combined with the non-druggability of most proteins, challenge genomics-based identification of oncology drug targets. We implemented a machine-learning-based approach (idTRAX), which relates cell-based screening of small-molecule compounds to their kinase inhibition data, to directly identify effective and readily druggable targets. We applied idTRAX to triple-negative breast cancer cell lines and efficiently identified cancer-selective targets. For example, we found that inhibiting AKT selectively kills MFM-223 and CAL148 cells, while inhibiting FGFR2 only kills MFM-223. Since the effects of catalytically inhibiting a protein can diverge from those of reducing its levels, targets identified by idTRAX frequently differ from those identified through gene knockout/knockdown methods. This is critical if the purpose is to identify targets specifically for small-molecule drug development, whereby idTRAX may produce fewer false-positives. The rapid nature of the approach suggests that it may be applicable in personalizing therapy.

Knowledge, attitude, behaviour of the future healthcare professionals towards the self-medication practice with antibiotics

Introduction: Self-medication with antibiotics (SMA) is a major health problem in the developing world including the kingdom of Saudi Arabia (KSA). This practice remains an emerging challenge for the healthcare providers. A few previous studies have estimated the prevalence of SMA among the general population of KSA, but there had been no such studies on healthcare students. We aimed to estimate the prevalence of SMA among medical, non-medical students and to evaluate its determinants. Methodology: A survey-based cross-sectional study using validated questionnaire was conducted amongst students at King Faisal University in KSA. Chi-square test and logistic regression analysis were applied to identify the determinants of SMA. Results: The prevalence of SMA was 58.4% with significantly lower proportion among medical students. Tonsillitis was the most common symptom for which SMA was used and was reported by a significantly higher proportion of medical (54.1%) students. Despite, the awareness of medical students about SMA is unsafe and mal-practice (79.9%), the prevalence of SMA practice remains high. Logistic regression analysis showed that students who incorrectly, identified the effectiveness of antibiotics in treating bacterial infections, the reasons of the antibiotics discontinuation had a higher likelihood to SMA. (OR = 2.16, 95% CI: 1.52-4.503, P = 0.001), (OR = 1.575, 95% CI: 0.923-2.686, P = 0.09), respectively. Conclusions: SMA remains noticeably high among the medical students. To overcome this problem, we highly recommend improving the health education to better address this malpractice and improve the students’ knowledge, attitudes and awareness towards the antibiotics use and prescription pattern.

Enhancement of BDNF Expression and Memory by HDAC Inhibition Requires BET Bromodomain Reader Proteins

Histone deacetylase (HDAC) inhibitors may have therapeutic utility in multiple neurological and psychiatric disorders, but the underlying mechanisms remain unclear. Here, we identify BRD4, a BET bromodomain reader of acetyl-lysine histones, as an essential component involved in potentiated expression of brain-derived neurotrophic factor (BDNF) and memory following HDAC inhibition. In in vitro studies, we reveal that pharmacological inhibition of BRD4 reversed the increase in BDNF mRNA induced by the class I/IIb HDAC inhibitor suberoylanilide hydroxamic acid (SAHA). Knock-down of HDAC2 and HDAC3, but not other HDACs, increased BDNF mRNA expression, whereas knock-down of BRD4 blocked these effects. Using dCas9-BRD4, locus-specific targeting of BRD4 to the BDNF promoter increased BDNF mRNA. In additional studies, RGFP966, a pharmacological inhibitor of HDAC3, elevated BDNF expression and BRD4 binding to the BDNF promoter, effects that were abrogated by JQ1 (an inhibitor of BRD4). Examining known epigenetic targets of BRD4 and HDAC3, we show that H4K5ac and H4K8ac modifications and H4K5ac enrichment at the BDNF promoter were elevated following RGFP966 treatment. In electrophysiological studies, JQ1 reversed RGFP966-induced enhancement of LTP in hippocampal slice preparations. Last, in behavioral studies, RGFP966 increased subthreshold novel object recognition memory and cocaine place preference in male C57BL/6 mice, effects that were reversed by cotreatment with JQ1. Together, these data reveal that BRD4 plays a key role in HDAC3 inhibitor-induced potentiation of BDNF expression, neuroplasticity, and memory.SIGNIFICANCE STATEMENT Some histone deacetylase (HDAC) inhibitors are known to have neuroprotective and cognition-enhancing properties, but the underlying mechanisms have yet to be fully elucidated. In the current study, we reveal that BRD4, an epigenetic reader of histone acetylation marks, is necessary for enhancing brain-derived neurotrophic factor (BDNF) expression and improved memory following HDAC inhibition. Therefore, by identifying novel epigenetic regulators of BDNF expression, these data may lead to new therapeutic targets for the treatment of neuropsychiatric disorders.

Detection and Quantification of Lipid Droplets in Differentiated Human Podocytes

Lipid droplets (LDs) are dynamic organelles that regulate the storage and homeostasis of intracellular triglycerides and other neutral lipids. Studies show that the number, morphology, and subcellular localization of LDs are altered in a growing number of diseases. As such, methodologies for imaging and quantifying LDs have become essential tools for detecting changes in cellular lipid metabolism, which could be an important indicator of disease onset or progression. We previously reported on the accumulation of LDs in podocytes of the kidney glomerulus in nephrological diseases of metabolic and non-metabolic origin. Here, we describe a high-content analysis (HCA) method for automated detection and quantification of LDs in differentiated human podocytes.

Scaffold Ranking and Positional Scanning Identify Novel Neurite Outgrowth Promoters with Nanomolar Potency

Central nervous system (CNS) neurons typically fail to regrow their axons after injury. Injuries or neuropathies that damage CNS axons and disrupt neuronal circuitry often result in permanent functional deficits. Axon regeneration is therefore an intensely pursued therapeutic strategy for numerous CNS disorders. Phenotypic screens utilizing primary neurons have proven successful at identifying agents that promote axon regeneration in vivo. Here, we report the screening of mixture-based combinatorial small molecule libraries in a phenotypic assay utilizing primary CNS neurons and the discovery of neurite outgrowth promoters with low nanomolar potency.

Identification of lead anti-human cytomegalovirus compounds targeting MAP4K4 via machine learning analysis of kinase inhibitor screening data

Chemogenomic approaches involving highly annotated compound sets and cell based high throughput screening are emerging as a means to identify novel drug targets. We have previously screened a collection of highly characterized kinase inhibitors (Khan et al., Journal of General Virology, 2016) to identify compounds that increase or decrease expression of a human cytomegalovirus (HCMV) protein in infected cells. To identify potential novel anti-HCMV drug targets we used a machine learning approach to relate our phenotypic data from the aforementioned screen to kinase inhibition profiling of compounds used in this screen. Several of the potential targets had no previously reported role in HCMV replication. We focused on one potential anti-HCMV target, MAPK4K, and identified lead compounds inhibiting MAP4K4 that have anti-HCMV activity with little cellular cytotoxicity. We found that treatment of HCMV infected cells with inhibitors of MAP4K4, or an siRNA that inhibited MAP4K4 production, reduced HCMV replication and impaired detection of IE2-60, a viral protein necessary for efficient HCMV replication. Our findings demonstrate the potential of this machine learning approach to identify novel anti-viral drug targets, which can inform the discovery of novel anti-viral lead compounds.

Abstract 4647: Identifying drug targets in sarcoma using machine learning and cell phenotype-based compound screening

High-throughput phenotypic screens that incorporate compound biochemical activity annotations are positioned for novel target discovery in cancer. We used machine learning approaches to correlate kinome-wide profiling data of a collection of kinase inhibitors with phenotypic cell proliferation data for the same compounds. We assembled a library of profiled kinase inhibitors with diverse chemotypes and kinome-wide selectivities and determined their anti-proliferative activities in a panel of sarcoma cell lines. Using a previously published machine learning algorithm, we related the compound inhibition profiles across 237 kinases to their abilities to inhibit cell proliferation. This identified Protein Kinase D (PRKD) as a putative novel target kinase selectively in synovial sarcoma cell lines, such that its inhibition leads to a decrease in proliferation in these cells. Next, we reasoned that our approach could be leveraged to identify targets that, when co-inhibited, induce a synergistic phenotype. This would enable rational design of drug combinations for further testing as opposed to the labor-intensive, random, pairwise testing commonly performed. To identify targets synergistic with PRKD, we performed a screen of a synovial sarcoma cell line in the presence of a selective PRKD inhibitor. Several kinases became prioritized as new targets in this “synergy screen.” Combining selective inhibitors for each synergistic target, as defined by Chou-Talalay, (here, CDK and AKT) with PRKD inhibitors synergistically reduced synovial sarcoma cell proliferation. Conversely, combining PRKD inhibitors with a selective inhibitor of a kinase that was deprioritized in the synergy screen (p38 MAPK) resulted in non-synergistic or even antagonistic effects. Overall, our approach provides a promising framework to identify new targets of cancer subtypes and a novel methodology to identify new combinational strategies for treatment.

Citation Format: Eric J. Lachacz, Zhi Fen Wu, John L. Bixby, Vance P. Lemmon, Sofia D. Merajver, Hassan Al-Ali, Matthew B. Soellner. Identifying drug targets in sarcoma using machine learning and cell phenotype-based compound screening [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 4647.

Soluble laminin polymers enhance axon growth of primary neurons in vitro

A substrate of laminin polymers formed at pH 4 (acidic pH-induced laminin; aLam) promotes neurite growth of embryonic rat cortical neurons better than a substrate of similar but structurally different laminin polymers formed at neutral pH (neutral pH-induced laminin; nLam). We investigated the effects of these laminin polymers, used as soluble supplements, on neurite growth of cultured adult rat primary dorsal root ganglion neurons. When added to the culture medium, aLam was found to promote neurite growth about twofold better than nLam. Immunoblocking experiments revealed that aLam elicited neurite growth to a similar extent through the α1 or α3 integrin subunit, while nLam required the availability of the α1 integrin subunit to elicit neurite growth. With aLam, but not nLam, immunoblocking of the α1 or α3 subunit resulted in an increase in the protein level of the alternative subunit. The presence of a mature focal adhesion complex, which is associated with neurite growth, was elevated in neurons in the presence of aLam relative to nLam or culture medium. Our data indicated that the two types of laminin polymers promote neurite growth of adult rat primary sensory neurons to a different degree, likely through different ligand-receptor interactions. These findings support the potential of soluble laminin polymers as injectable therapeutics for eliciting axon growth after nervous system injury. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 106A:2372-2381, 2018.

Gain of function of ASXL1 truncating protein in the pathogenesis of myeloid malignancies

Additional Sex Combs-Like 1 (ASXL1) is mutated at a high frequency in all forms of myeloid malignancies associated with poor prognosis. We generated a Vav1 promoter-driven Flag-Asxl1Y588X transgenic mouse model, Asxl1Y588X Tg, to express a truncated FLAG-ASXL1aa1-587 protein in the hematopoietic system. The Asxl1Y588X Tg mice had an enlarged hematopoietic stem cell (HSC) pool, shortened survival, and predisposition to a spectrum of myeloid malignancies, thereby recapitulating the characteristics of myeloid malignancy patients with ASXL1 mutations. ATAC- and RNA-sequencing analyses revealed that the ASXL1aa1-587 truncating protein expression results in more open chromatin in cKit+ cells compared with wild-type cells, accompanied by dysregulated expression of genes critical for HSC self-renewal and differentiation. Liquid chromatography-tandem mass spectrometry and coimmunoprecipitation experiments showed that ASXL1aa1-587 acquired an interaction with BRD4. An epigenetic drug screening demonstrated a hypersensitivity of Asxl1Y588X Tg bone marrow cells to BET bromodomain inhibitors. This study demonstrates that ASXL1aa1-587 plays a gain-of-function role in promoting myeloid malignancies. Our model provides a powerful platform to test therapeutic approaches of targeting the ASXL1 truncation mutations in myeloid malignancies.

Abstract A149: A chemical screening and machine learning approach to de-convolve kinase addictions in TNBC

Protein kinases are major regulators of cellular signalling and known drivers of cancer and other diseases. In the last two decades, kinase inhibitors have gained much attention as cancer therapeutic agents. In this study, we combined drug vulnerability data of 19 breast cancer cell lines with kinase activity data, and employed machine learning and information theory to de-convolve cell line specific kinase addictions. The study was mainly focused on triple-negative breast cancers (TNBC), which still lack targeted therapy. With this approach, we identified several novel TNBC cell line selective kinase addictions (e.g., FGFR2 for MFM-223) and, as added validation, detected previously established kinase sensitivities (e.g., BRAF in DU4475, ERBB2 in luminal cell lines SK-BR-3 and BT-474, along with generic addiction towards cell cycle and apoptosis regulators like PLK1 and PI3K). A major benefit of this approach is that it can identify readily druggable targets while avoiding false positives and undruggable candidates from loss-of-function analyses. Comparison of kinase inhibitor vulnerabilities with loss-of-function data showed significant discordance, highlighting the need for cautious evaluation of loss-of-function data for drug target identification. Our study underscores the heterogeneity of drug response in TNBC and provides a platform for rapidly identifying vulnerabilities and guiding targeted therapy regimens.

Citation Format: Prson Gautam, Hassan Al-Ali, Krister Wennerberg. A chemical screening and machine learning approach to de-convolve kinase addictions in TNBC [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2017 Oct 26-30; Philadelphia, PA. Philadelphia (PA): AACR; Mol Cancer Ther 2018;17(1 Suppl):Abstract nr A149.

Ex-vivo sensitivity profiling to guide clinical decision making in acute myeloid leukemia: A pilot study

A precision medicine approach is appealing for use in AML due to ease of access to tumor samples and the significant variability in the patients' response to treatment. Attempts to establish a precision medicine platform for AML, however, have been unsuccessful, at least in part due to the use of small compound panels and having relatively slow turn over rates, which restricts the scope of treatment and delays its onset. For this pilot study, we evaluated a cohort of 12 patients with refractory AML using an ex vivo drug sensitivity testing (DST) platform. Purified AML blasts were screened with a panel of 215 FDA-approved compounds and treatment response was evaluated after 72h of exposure. Drug sensitivity scoring was reported to the treating physician, and patients were then treated with either DST- or non-DST guided therapy. We observed survival benefit of DST-guided therapy as compared to the survival of patients treated according to physician recommendation. Three out of four DST-treated patients displayed treatment response, while all of the non-DST-guided patients progressed during treatment. DST rapidly and effectively provides personalized treatment recommendations for patients with refractory AML.

High content analysis of phagocytic activity and cell morphology with PuntoMorph

BACKGROUND

Phagocytosis is essential for maintenance of normal homeostasis and healthy tissue. As such, it is a therapeutic target for a wide range of clinical applications. The development of phenotypic screens targeting phagocytosis has lagged behind, however, due to the difficulties associated with image-based quantification of phagocytic activity.

NEW METHOD

We present a robust algorithm and cell-based assay system for high content analysis of phagocytic activity. The method utilizes fluorescently labeled beads as a phagocytic substrate with defined physical properties. The algorithm employs statistical modeling to determine the mean fluorescence of individual beads within each image, and uses the information to conduct an accurate count of phagocytosed beads. In addition, the algorithm conducts detailed and sophisticated analysis of cellular morphology, making it a standalone tool for high content screening.

RESULTS

We tested our assay system using microglial cultures. Our results recapitulated previous findings on the effects of microglial stimulation on cell morphology and phagocytic activity. Moreover, our cell-level analysis revealed that the two phenotypes associated with microglial activation, specifically cell body hypertrophy and increased phagocytic activity, are not highly correlated. This novel finding suggests the two phenotypes may be under the control of distinct signaling pathways.

COMPARISON WITH EXISTING METHODS

We demonstrate that our assay system outperforms preexisting methods for quantifying phagocytic activity in multiple dimensions including speed, accuracy, and resolution.

CONCLUSIONS

We provide a framework to facilitate the development of high content assays suitable for drug screening. For convenience, we implemented our algorithm in a standalone software package, PuntoMorph.

Progress towards a public chemogenomic set for protein kinases and a call for contributions

Protein kinases are highly tractable targets for drug discovery. However, the biological function and therapeutic potential of the majority of the 500+ human protein kinases remains unknown. We have developed physical and virtual collections of small molecule inhibitors, which we call chemogenomic sets, that are designed to inhibit the catalytic function of almost half the human protein kinases. In this manuscript we share our progress towards generation of a comprehensive kinase chemogenomic set (KCGS), release kinome profiling data of a large inhibitor set (Published Kinase Inhibitor Set 2 (PKIS2)), and outline a process through which the community can openly collaborate to create a KCGS that probes the full complement of human protein kinases.

RegenBase: a knowledge base of spinal cord injury biology for translational research

Spinal cord injury (SCI) research is a data-rich field that aims to identify the biological mechanisms resulting in loss of function and mobility after SCI, as well as develop therapies that promote recovery after injury. SCI experimental methods, data and domain knowledge are locked in the largely unstructured text of scientific publications, making large scale integration with existing bioinformatics resources and subsequent analysis infeasible. The lack of standard reporting for experiment variables and results also makes experiment replicability a significant challenge. To address these challenges, we have developed RegenBase, a knowledge base of SCI biology. RegenBase integrates curated literature-sourced facts and experimental details, raw assay data profiling the effect of compounds on enzyme activity and cell growth, and structured SCI domain knowledge in the form of the first ontology for SCI, using Semantic Web representation languages and frameworks. RegenBase uses consistent identifier schemes and data representations that enable automated linking among RegenBase statements and also to other biological databases and electronic resources. By querying RegenBase, we have identified novel biological hypotheses linking the effects of perturbagens to observed behavioral outcomes after SCI. RegenBase is publicly available for browsing, querying and download.

Database URL:http://regenbase.org

In vitro models of axon regeneration

A variety of in vitro models have been developed to understand the mechanisms underlying the regenerative failure of central nervous system (CNS) axons, and to guide pre-clinical development of regeneration-promoting therapeutics. These range from single-cell based assays that typically focus on molecular mechanisms to organotypic assays that aim to recapitulate in vivo behavior. By utilizing a combination of models, researchers can balance the speed, convenience, and mechanistic resolution of simpler models with the biological relevance of more complex models. This review will discuss a number of models that have been used to build our understanding of the molecular mechanisms of CNS axon regeneration.

Phenotypic Screening of Small-Molecule Inhibitors: Implications for Therapeutic Discovery and Drug Target Development in Traumatic Brain Injury

The inability of central nervous system (CNS) neurons to regenerate damaged axons and dendrites following traumatic brain injury (TBI) creates a substantial obstacle for functional recovery. Apoptotic cell death, deposition of scar tissue, and growth-repressive molecules produced by glia further complicate the problem and make it challenging for re-growing axons to extend across injury sites. To date, there are no approved drugs for the treatment of TBI, accentuating the need for relevant leads. Cell-based and organotypic bioassays can better mimic outcomes within the native CNS microenvironment than target-based screening methods and thus should speed the discovery of therapeutic agents that induce axon or dendrite regeneration. Additionally, when used to screen focused chemical libraries such as small-molecule protein kinase inhibitors, these assays can help elucidate molecular mechanisms involved in neurite outgrowth and regeneration as well as identify novel drug targets. Here, we describe a phenotypic cellular (high content) screening assay that utilizes brain-derived primary neurons for screening small-molecule chemical libraries.

The evolution of drug discovery: from phenotypes to targets, and back

Cumulative scientific and technological advances over the past two centuries have transformed drug discovery from a largely serendipitous process into the high tech pipelines of today.

Rational Polypharmacology: Systematically Identifying and Engaging Multiple Drug Targets To Promote Axon Growth

Mammalian central nervous system (CNS) neurons regrow their axons poorly following injury, resulting in irreversible functional losses. Identifying therapeutics that encourage CNS axon repair has been difficult, in part because multiple etiologies underlie this regenerative failure. This suggests a particular need for drugs that engage multiple molecular targets. Although multitarget drugs are generally more effective than highly selective alternatives, we lack systematic methods for discovering such drugs. Target-based screening is an efficient technique for identifying potent modulators of individual targets. In contrast, phenotypic screening can identify drugs with multiple targets; however, these targets remain unknown. To address this gap, we combined the two drug discovery approaches using machine learning and information theory. We screened compounds in a phenotypic assay with primary CNS neurons and also in a panel of kinase enzyme assays. We used learning algorithms to relate the compounds' kinase inhibition profiles to their influence on neurite outgrowth. This allowed us to identify kinases that may serve as targets for promoting neurite outgrowth as well as others whose targeting should be avoided. We found that compounds that inhibit multiple targets (polypharmacology) promote robust neurite outgrowth in vitro. One compound with exemplary polypharmacology was found to promote axon growth in a rodent spinal cord injury model. A more general applicability of our approach is suggested by its ability to deconvolve known targets for a breast cancer cell line as well as targets recently shown to mediate drug resistance.

Phenotypic assays to identify agents that induce reactive gliosis: a counter-screen to prioritize compounds for preclinical animal studies

Astrocyte phenotypes change in a process called reactive gliosis after traumatic central nervous system (CNS) injury. Astrogliosis is characterized by expansion of the glial fibrillary acidic protein (GFAP) cytoskeleton, adoption of stellate morphologies, and differential expression of some extracellular matrix molecules. The astrocytic response immediately after injury is beneficial, but in the chronic injury phase, reactive astrocytes produce inhibitory factors (i.e., chondroitin sulfate proteoglycans [CSPGs]) that limit the regrowth of injured axons. There are no drugs that promote axon regeneration or functional recovery after CNS trauma in humans. To develop novel therapeutics for the injured CNS, we screened various libraries in a phenotypic assay to identify compounds that promote neurite outgrowth. However, the effects these compounds have on astrocytes are unknown. Specifically, we were interested in whether compounds could alter astrocytes in a manner that mimics the glial reaction to injury. To test this hypothesis, we developed cell-based phenotypic bioassays to measure changes in (1) GFAP morphology/localization and (2) CSPG expression/immunoreactivity from primary astrocyte cultures. These assays were optimized for six-point dose-response experiments in 96-well plates. The GFAP morphology assay is suitable for counter-screening with a Z-factor of 0.44±0.03 (mean±standard error of the mean; N=3 biological replicates). The CSPG assay is reproducible and informative, but does not satisfy common metrics for a "screenable" assay. As proof of principle, we tested a small set of hit compounds from our neurite outgrowth bioassay and identified one that can enhance axon growth without exacerbating the deleterious characteristics of reactive gliosis.

Risk factors associated with recurrence in patients with solid pseudopapillary tumors of the pancreas

CONTEXT

Solid pseudopapillary tumors (SPT) are rare, generally low grade pancreatic neoplasms that occasionally display malignant behavior.

OBJECTIVE

To analyze the clinical and pathological features associated with increased risk of recurrence of SPT.

METHODS

Cohort study of patients with SPT who underwent resection of the primary tumor and in selected cases resection of metastatic disease from 1999-2013 at a single tertiary care Hepatopancreatobiliary center. Risk factors for recurrence were statistically analyzed.

RESULTS

There were 32 patients. The mean age was 35.65 years (standard deviation: 12.26), 26/32, 81.25% were female. Median size of resected tumors was 4.7 cm (1.1-14.5). Most were solid and cystic (22/32, 68.75%), encapsulated (27/32, 84.4%) and located in the pancreatic body or tail (22/32, 68.75%). All displayed strong β-catenin, cyclin D1, CD56, and progesterone receptor staining with loss of E-cadherin. Most stained positive for vimentin (15/16, 93.75%) and CD10 (17/18, 94.4%). Median follow-up was 43 months (range: 3-207); 3/32, 9.38% recurred (all after 5-years from curative resection) and 1 died by the end of the study period, 11 years after diagnosis. Patients who developed recurrences (n=3) more commonly had synchronous metastases at presentation (P=0.006), lymphovascular invasion (P=0.04) and invasion of tumor capsule (P=0.08) compared to those who did not have disease recurrence.

CONCLUSIONS

Lymphovascular invasion, synchronous metastases and local invasion of tumor capsule are associated with aggressive behavior. Since recurrences may occur >5 years from resection, this high-risk group should undergo extended follow-up. Progression and recurrence is slow, therefore, resection of liver metastases can offer long-term survival.

Chemical interrogation of the neuronal kinome using a primary cell-based screening assay

A fundamental impediment to functional recovery from spinal cord injury (SCI) and traumatic brain injury is the lack of sufficient axonal regeneration in the adult central nervous system. There is thus a need to develop agents that can stimulate axon growth to re-establish severed connections. Given the critical role played by protein kinases in regulating axon growth and the potential for pharmacological intervention, small molecule protein kinase inhibitors present a promising therapeutic strategy. Here, we report a robust cell-based phenotypic assay, utilizing primary rat hippocampal neurons, for identifying small molecule kinase inhibitors that promote neurite growth. The assay is highly reliable and suitable for medium-throughput screening, as indicated by its Z'-factor of 0.73. A focused structurally diverse library of protein kinase inhibitors was screened, revealing several compound groups with the ability to strongly and consistently promote neurite growth. The best performing bioassay hit robustly and consistently promoted axon growth in a postnatal cortical slice culture assay. This study can serve as a jumping-off point for structure activity relationship (SAR) and other drug discovery approaches toward the development of drugs for treating SCI and related neurological pathologies.

Up-front hepatic resection for metastatic colorectal cancer results in favorable long-term survival

BACKGROUND

Hepatic metastasis from colorectal cancer (CRC) is best managed with a multimodal approach; however, the optimal timing of liver resection in relation to administration of perioperative chemotherapy remains unclear. Our strategy has been to offer up-front liver resection for patients with resectable hepatic metastases, followed by post-liver resection chemotherapy. We report the outcomes of patients based on this surgical approach.

METHODS

A retrospective review of all patients undergoing liver resection for CRC metastases over a 5-year period (2002-2007) was performed. Associations between clinicopathologic factors and survival were evaluated by the Cox proportional hazard method.

RESULTS

A total of 320 patients underwent 336 liver resections. Median follow-up was 40 (range 8-80) months. The majority (n=195, 60.9%) had metachronous disease, and most patients (n=286, 85%) had a major hepatectomy (>3 segments). Thirty-six patients (11%) received preoperative chemotherapy, predominantly for downstaging unresectable disease. Ninety-day mortality was 2.1%, and perioperative morbidity occurred in 68 patients (20.2%). Actual disease-free survival at 3 and 5 years was 46.2% and 42%, respectively. Actual overall survival (OS) at 3 and 5 years was 63.7% and 55%, respectively. Multivariate analysis identified four factors that were independently associated with differences in OS (hazard ratio; 95% confidence interval): size of metastasis>6 cm (2.2; 1.3-3.5), positive lymph node status of the primary CRC (N1 (2.0; 1.0-3.8), N2 (2.4; 1.2-4.9)), synchronous disease (2.1; 1.3-3.5), and treatment with chemotherapy after liver resection (0.42; 0.23-0.75).

CONCLUSIONS

Up-front surgery for patients with resectable CRC liver metastases, followed by chemotherapy, can lead to favorable OS.

Adult metachromatic leukodystrophy treated by allo-SCT and a review of the literature

Five patients with adult-onset metachromatic leukodystrophy (MLD) underwent allo-SCT. Conditioning was reduced in intensity and grafts were obtained from voluntary unrelated donors. All but one graft were depleted of T-lymphocytes. Patient age at transplantation varied from 18 to 29 (median, 27) years. Two patients rejected their graft and MLD progressed. The recipient of the unmanipulated graft converted to complete donor chimerism with normalization of arylsulphatase A (ARSA) levels. Despite ARSA normalization, he deteriorated. Another patient was a mixed chimera. Following escalated doses of donor lymphocyte infusions he converted to complete donor chimerism. His levels of ARSA correlated positively with the percentage of donor cells and MLD was not progressive. The fifth patient died after 35 days from complications associated with GVHD. We conclude that results of allo-SCT in symptomatic MLD patients are poor. However, allo-SCT may stop progression of MLD in selected patients.

The conserved mitochondrial twin Cx9C protein Cmc2 Is a Cmc1 homologue essential for cytochrome c oxidase biogenesis

Mitochondrial copper metabolism and delivery to cytochrome c oxidase and mitochondrially localized CuZn-superoxide dismutase (Sod1) requires a growing number of intermembrane space proteins containing a twin Cx(9)C motif. Among them, Cmc1 was recently identified by our group. Here we describe another conserved mitochondrial metallochaperone-like protein, Cmc2, a close homologue of Cmc1, whose function affects both cytochrome c oxidase and Sod1. In the yeast Saccharomyces cerevisiae, Cmc2 localizes to the mitochondrial inner membrane facing the intermembrane space. In the absence of Cmc2, cytochrome c oxidase activity measured spectrophotometrically and cellular respiration measured polarographically are undetectable. Additionally, mutant cmc2 cells display 2-fold increased mitochondrial Sod1 activity, whereas CMC2 overexpression results in Sod1 activity decreased to 60% of wild-type levels. CMC1 overexpression does not rescue the respiratory defect of cmc2 mutants or vice versa. However, Cmc2 physically interacts with Cmc1 and the absence of Cmc2 induces a 5-fold increase in Cmc1 accumulation in the mitochondrial membranes. Cmc2 function is conserved from yeast to humans. Human CMC2 localizes to the mitochondria and CMC2 expression knockdown produces cytochrome c oxidase deficiency in Caenorhabditis elegans. We conclude that Cmc1 and Cmc2 have cooperative but nonoverlapping functions in cytochrome c oxidase biogenesis.

Biophysical characterization reveals structural disorder in the developmental transcriptional regulator LBH

Limb-bud and heart (LBH) is a key transcriptional regulator in vertebrates with pivotal roles in embryonic development and human disease. Herein, using a diverse array of biophysical techniques, we report the first structural characterization of LBH pertinent to its biological function. Our data reveal that LBH is structurally disordered with no discernable secondary or tertiary structure and exudes rod-like properties in solution. Consistent with these observations, we also demonstrate that LBH is conformationally flexible and thus may be capable of adapting distinct conformations under specific physiological contexts. We propose that LBH is a member of the intrinsically disordered protein (IDP) family, and that conformational plasticity may play a significant role in modulating LBH-dependent transcriptional processes.

An Inductive Logic Programming Approach to Validate Hexose Binding Biochemical Knowledge

Hexoses are simple sugars that play a key role in many cellular pathways, and in the regulation of development and disease mechanisms. Current protein-sugar computational models are based, at least partially, on prior biochemical findings and knowledge. They incorporate different parts of these findings in predictive black-box models. We investigate the empirical support for biochemical findings by comparing Inductive Logic Programming (ILP) induced rules to actual biochemical results. We mine the Protein Data Bank for a representative data set of hexose binding sites, non-hexose binding sites and surface grooves. We build an ILP model of hexose-binding sites and evaluate our results against several baseline machine learning classifiers. Our method achieves an accuracy similar to that of other black-box classifiers while providing insight into the discriminating process. In addition, it confirms wet-lab findings and reveals a previously unreported Trp-Glu amino acids dependency.

Hematopoietic cell transplantation (HCT) after low-dose, total body irradiation-based regimen increased leukemia-free survival (LFS) in elderly patients with cytogenetic high-risk AML compared to chemotherapy (OSHO 97 study)

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Background: Even after reaching initial CR, most AML patients > 60 years relapse within 2 years of diagnosis. Cytogenetic high risk AML (abn 3q26, abn 11q23, -5/5q-, -7/7q- and complex) has an even worse prognosis. Attempts to improve survival by intensifying consolidation chemotherapy have so far failed. We investigated the role of allogeneic HCT in comparison to chemotherapy among patients with high risk cytogenetics entered into the OSHO AML 97 protocol. Methods: Initial treatment consisted of a course of induction therapy (AraC 2 g/m2 iv on day 1,3,5,7 + mitoxantrone 10 mg/m2 iv day 1 –3, repeated once in case of PR) followed by one consolidation course (AraC 240 mg/m2 iv day 1 –5 + mitoxantrone 10 mg/m2 iv day 1 –2). Patients in CR1 after the consolidation I were either treated with an additional consolidation therapy or with an allogeneic HCT from related (n=2) or unrelated (n=10) donors. Transplant patients were conditioned with fludarabine and TBI 200 cGy and immunosuppressed with cyclosporine and mycofenolate mofetil. Results: A total of 347 patients are evaluable. Of 105 (33%) patients with high-risk cytogenetics, 53 (50%) went into remission after one or two cycles of induction chemotherapy. Of these 53 patients, 42 received consolidation I and 35 patients were available for either consolidation II (n=23) or HCT (n=12). Median age of the patients receiving chemotherapy was 64 (range 61–77) years and that of the transplant patients was 64 (range 61–68) years. LFS at 4 years was 42 ± 14% after HCT and 15 ± 8% after chemotherapy. Major differences in relapse incidences were seen between the two groups, with the lowest RI at 4 years after HCT (36 ± 15%) followed by chemotherapy (85±8%, p<0.04). Treatment related mortality at 4 years was 35±17% and 0±0% for patients receiving HCT and chemotherapy, respectively (p<0.05). Conclusions: From these results, we conclude that consolidation with allogeneic HCT after minimal conditioning is superior to chemotherapy even in older patients with high risk cytogenetics. While differences in TRM were seen between the treatment arms, a lower relapse incidence after related and unrelated HCT contributed to the improved LFS.

No significant financial relationships to disclose.

Reconstitution of modular PDK1 functions on trans-splicing of the regulatory PH and catalytic kinase domains

The serine-threonine protein kinases PDK1 and PKB each contain a pleckstrin homology (PH) domain that binds the membrane-bound phosphatidylinositol 3,4,5-triphosphate [PI(3,4,5)P3] second messenger and is required for PDK1-catalyzed phosphorylation and activation of PKB. While X-ray structures have been reported for the individual regulatory PH and catalytic kinase domain constructs of both PDK1 and PKB, diffraction quality crystals of full length constructs have yet to be obtained, likely due to conformational heterogeneity. In developing alternative approaches to understanding the potential role of conformational dynamics in regulating PKB phosphorylation by PDK1, an efficient in vitro method for protein trans-splicing was developed, which utilizes the N- and C-terminal split inteins of the gene dnaE from Nostoc punctiforme [(N)NpuDnaE] and Synechocystis sp. strain PCC6803 [(C)SspDnaE], respectively. For conjugating the regulatory PH domain to the catalytic kinase domain of PDK1, the recombinant trans-splicing fusion constructs KINASE(AEY)-(N)NpuDnaE-His6 and GST-His6-(C)SspDnaE-(CMN)PH were designed, PCR assembled, overexpressed, and affinity purified. The cross-reacting (N)NpuDnaE and (C)SspDnaE inteins generated full length spliced-PDK1 with kobs = (2.8 +/- 0.3) x 10(-5) s(-1) and with < or =5% of any competing trans-cleavage reactions. Spliced-PDK1 was efficiently purified to > or =95% homogeneity from the reaction mixture by subsequent His6 affinity and ion exchange chromatography steps. In vitro kinase assays and phosphopeptide mapping studies confirmed that spliced-PDK1 retained the ability to colocalize and selectively phosphorylate Thr-309 of PKBbeta in a PI(3,4,5)P3-dependent manner. The high-level production and reconstitution of functional spliced-PDK1 establishes the feasibility of incorporating domain-specific biophysical probes for spectroscopic studies of regulatory PH domain mediated catalytic specificity.

Transmission of donor illness by stem cell transplantation: should screening be different in older donors?

With increasing donor age, the potential of transmitting diseases from donor to recipient reaches new dimensions. Potentially transmittable diseases from donors include infections, congenital disorders, and acquired illnesses like autoimmune diseases or malignancies of hematological or nonhematological origin. While established nonmalignant or malignant diseases might be easy to discover, early-stage hematological diseases like CML, light-chain multiple myelomas, aleukemic leukemias, occult myelodysplastic syndromes and other malignant and nonmalignant diseases might not be detectable by routine screening but only by invasive, new and/or expensive diagnostic tests. In the following article, we propose recommendations for donor work-up, taking into consideration the age of the donors. In contrast to blood transfusions, stem cells from donors with abnormal findings might still be acceptable for HCT, when no other options are available and life expectancy is limited. This issue is discussed in detail in relation to the available donor and stem cell source. Finally, the recommendations presented here aim at harmonized worldwide work-up for donors to insure high standard quality.

BCR-ABL transcripts are early predictors for hematological relapse in chronic myeloid leukemia after hematopoietic cell transplantation with reduced intensity conditioning

Kinetics of BCR-ABL transcript elimination and its prognostic implications on relapse were analyzed in patients with chronic myeloid leukemia (CML) after reduced intensity hematopoietic cell transplantation (HCT). In all, 19 CML patients were conditioned with 2 Gy total-body irradiation in combination with (n=14) or without (n=3) fludarabine 3 x 30 mg/m(2) (Flu) or 4.5 Gy total lymphoid irradiation (TLI) with Flu and OKT3 3 x 5 mg (n=2) and were treated with cyclosporine (CSP) and mycophenolate mofetil after allogeneic HCT. BCR-ABL transcripts were analyzed by nested RT-PCR and Taqman((R)) RT-PCR on days +28, +56 and +84 after HCT and were evaluated for their association with relapse. Of the 19 patients, 14 achieved sustained remissions of which six had a negative RT-PCR 28 days after HCT. Five patients relapsed +41, +54, +57, +136 and +234 days after HCT. Predictors for relapse were advanced disease stage (P=0.02) and slow reduction of BCR-ABL transcripts at day 28 (P=0.006) and day 56 (P=0.047) post-transplant. We conclude that a complete clearance of BCR-ABL transcripts is achievable within 4 weeks from HCT even after minimal conditioning and that early kinetics of BCR-ABL transcripts significantly correlate with the probability of hematological relapse.