Inter-night variability of in-home, overnight pulse oximetry screening in an asymptomatic older adult population.

PURPOSE: Obstructive sleep apnoea (OSA) is common, yet often undiagnosed. Self-administered, overnight pulse oximetry (OPO) could screen for OSA in asymptomatic, older populations. However, the inter-night variability of OPO in an asymptomatic, older population is unknown. We determined the inter-night variability of home OPO parameters in an older population and correlated with sleep questionnaires. METHODS: Participants > 50 years without a diagnosis of OSA undertook home OPO for three consecutive nights and completed two sleep questionnaires (STOP-BANG (SBQ) and Epworth Sleepiness Score (ESS)). Analysis was performed with linear mixed models and Spearman's correlation coefficient. RESULTS: There was no difference in oxygen desaturation index (ODI), MeanSpO2, MinimumSpO2, and time spent with SpO2 < 90% (T90) across two or three nights (P ≥ 0.282). However, the variability of all parameters across nights increased with the magnitude of departure from normal values (P ≤ 0.002). All OPO parameters were associated with age (P ≤ 0.034) and body mass index (P ≤ 0.049). There was a weak correlation between three OPO parameters and SBQ (absolute ρ = 0.22 to 0.32; P ≤ 0.021), but not ESS (P ≥ 0.254). CONCLUSION: Inter-night variability of home OPO was minimal when values were near-normal in an older population. However, as values depart from normal, the inter-night variability increases, indicating the need for multiple night recordings. Low correlation to sleep questionnaires suggest the need for more robust OSA questionnaires in an asymptomatic population.

Systematic review: What is the impact of triage implementation on clinical outcomes and process measures in low- and middle-income country emergency departments?

INTRODUCTION: Triage is widely regarded as an essential function of emergency care (EC) systems, especially in resource-limited settings. Through a systematic search and review of the literature, we investigated the effect of triage implementation on clinical outcomes and process measures in low- and middle-income country (LMIC) emergency departments (EDs). METHODS: Structured searches were conducted using MEDLINE, CENTRAL, EMBASE, CINAHL, and Global Health. Eligible articles identified through screening and full-text review underwent risk-of-bias assessment using the Newcastle-Ottawa Scale. The quality of evidence for each effect measure was summarized using GRADE. RESULTS: Among 10,394 articles identified through the search strategy, 58 underwent full-text review and 16 were included in the final synthesis. All utilized pre-/postintervention methods and a majority were single center. Effect measures included mortality, waiting time, length of stay, admission rate, and patient satisfaction. Of these, ED mortality and time to clinician assessment were evaluated most frequently. The majority of studies using these outcomes identified a positive effect, namely a reduction in deaths and waiting time among patients presenting for EC. The quality of the evidence was moderate for these measures but low or very low for all other outcomes and process indicators. CONCLUSIONS: There is moderate quality of evidence supporting an association between the introduction of triage and a reduction in deaths and waiting time. Although the available data support the value of triage in LMIC EDs, the risk of confounding and publication bias is significant. Future studies will benefit from more rigorous research methods.

Sequential appetite suppression by oral and visceral feedback to the brainstem.

The termination of a meal is controlled by dedicated neural circuits in the caudal brainstem. A key challenge is to understand how these circuits transform the sensory signals generated during feeding into dynamic control of behaviour. The caudal nucleus of the solitary tract (cNTS) is the first site in the brain where many meal-related signals are sensed and integrated1-4, but how the cNTS processes ingestive feedback during behaviour is unknown. Here we describe how prolactin-releasing hormone (PRLH) and GCG neurons, two principal cNTS cell types that promote non-aversive satiety, are regulated during ingestion. PRLH neurons showed sustained activation by visceral feedback when nutrients were infused into the stomach, but these sustained responses were substantially reduced during oral consumption. Instead, PRLH neurons shifted to a phasic activity pattern that was time-locked to ingestion and linked to the taste of food. Optogenetic manipulations revealed that PRLH neurons control the duration of seconds-timescale feeding bursts, revealing a mechanism by which orosensory signals feed back to restrain the pace of ingestion. By contrast, GCG neurons were activated by mechanical feedback from the gut, tracked the amount of food consumed and promoted satiety that lasted for tens of minutes. These findings reveal that sequential negative feedback signals from the mouth and gut engage distinct circuits in the caudal brainstem, which in turn control elements of feeding behaviour operating on short and long timescales.

Role of sleep-disordered breathing in age-related macular degeneration.

AIMS: To examine the association between obstructive sleep apnoea (OSA) and age-related macular degeneration (AMD), and the subphenotype of AMD with reticular pseudodrusen (RPD). METHODS: Case-control study with 351 participants (211 AMD and 140 controls) using the Epworth Sleepiness Scale (ESS) and the STOP-BANG Questionnaire (SBQ) validated sleep questionnaires. Participant risk of having moderate-to-severe OSA was determined using a binary risk scale based on the ESS and SBQ combined and an ordinal risk scale based on the SBQ. A prior diagnosis of OSA and whether receiving assisted breathing treatment was also ascertained. Retinal imaging allowed AMD and RPD determination. RESULTS: Higher risk of moderate-to-severe OSA according to the binary and ordinal scales was not associated with the presence of AMD (p≥0.519) nor AMD with RPD (p≥0.551). Per point increase in ESS or SBQ questionnaire score was also not associated with AMD nor AMD with RPD (p≥0.252). However, being on assisted breathing treatment for diagnosed OSA was significantly associated with a higher likelihood of having AMD with RPD, but not all AMD, (OR 3.70; p=0.042 and OR 2.70; p=0.149, respectively), when compared with those without diagnosed OSA on treatment. CONCLUSIONS: Formally diagnosed OSA undergoing treatment, increased the likelihood of having AMD with RPD, but not overall AMD compared with those who were not undergoing treatment. Risk-based OSA questionnaires showed no difference in risk for all AMD or AMD with RPD. Future research, using formal sleep studies could further explore the potential role of nocturnal hypoxia in AMD.

Cannula provoked upper extremity superficial vein thrombophlebitis: are we overtreating?

Cannula provoked upper extremity superficial vein thrombophlebitis (UESVT) is common. Retrospective audit of 93 consecutive patients, 51% male, median age 57 years (range 20-91), with symptomatic UESVT revealed varied management including symptomatic management (37%), prophylactic (37%) and higher dose anticoagulation (27%). There was 2% (95% confidence interval (CI) 0-7.6) thrombus extension and 1% (95% CI 0-5.9) major bleeding, both limited to cancer. We argue anticoagulation is unnecessary in most UESVT patients.

Hypophosphataemia after ferric carboxymaltose is unrelated to symptoms, intestinal inflammation or vitamin D status.

BACKGROUND: Intravenous iron replacement is recommended for iron-deficient patients with inflammatory bowel disease (IBD), but may be associated with hypophosphataemia, predisposing to osteomalacia and fractures. This study aimed to evaluate the incidence and risk factors for hypophosphataemia following intravenous ferric carboxymaltose (FCM) in patients with IBD. METHODS: This prospective observational study of patients with and without IBD evaluated serum phosphate for 28 days following intravenous FCM, and assessed associations with symptoms, markers of inflammation and vitamin D status. RESULTS: Twenty-four patients with IBD (11 with Crohn's disease [CD], 13 with ulcerative colitis [UC], mean age 45 years [range 19-90], 7 female), and 20 patients without IBD (mean age 56 [22-88] y, 11 female), were included. Overall, serum phosphate declined by a mean of 36% at Day 7, with a mean fall of 42% (SD 19%) at some time point over 28 days (p <  0.001). Twenty-four of 44 (55%) patients developed moderate to severe hypophosphataemia (serum phosphate < 0.6 mmol/L). No differences between patients with and without IBD were seen, but patients with CD had greater decline in phosphate than those with UC. There was no association between hypophosphataemia and symptomatic adverse events, faecal calprotectin, C-reactive protein, albumin, platelet count, 25(OH) vitamin D, or 1,25(di-OH) vitamin D. Serum phosphate < 1.05 mmol/L on Day 2 predicted susceptibility to moderate-severe hypophosphataemia (OR 7.0). CONCLUSIONS: Hypophosphataemia following FCM is common, unrelated to symptomatic adverse events, baseline intestinal or systemic inflammation, or vitamin D status.

Risk Stratification of Acute Pulmonary Embolism and Determining the Effect on Chronic Cardiopulmonary Complications: The REACH Study.

Introduction Patients with acute pulmonary embolism (PE) are at risk of developing chronic complications including the post-PE syndrome with reduced cardiopulmonary function and chronic thromboembolism pulmonary hypertension (CTEPH). Risk stratification at PE diagnosis is an important tool in predicting early mortality; however, its use in predicting chronic complications has not been evaluated. Objective This study investigates the effect of initial risk stratification of intermediate risk and standard risk PE on the rate of development of chronic complications including right ventricular (RV) dysfunction, residual perfusion defects, and CTEPH. Methods Cases of acute PE ( n = 1,524) were identified using International Statistical Classification of Diseases and Related Health Problems, Tenth Revision, Australian Modification discharge diagnosis coding for PE. Evidence of RV dysfunction and systolic blood pressure < 90 mm Hg were used to risk stratify into high, intermediate and standard risk PE. Results There were 508 patients included in the analysis. Intermediate risk PE was associated with higher rates of persistent RV dysfunction as well as residual perfusion defects on repeat imaging. The overall rate of CTEPH was low (0.6%) and there was no difference between the intermediate risk and standard risk PE groups. Conclusion These findings demonstrate that acute intermediate risk PE is associated with higher rates of RV dysfunction on follow-up imaging than standard risk PE. However, the rate of CTEPH was similar between the two groups and overall the CTEPH rate was low among all patients with intermediate and standard risk PE.

Symptomatic severe hypophosphatemia after intravenous ferric carboxymaltose.

Intravenous iron is commonly prescribed for treatment of iron deficiency, with modern formulations demonstrating an acceptable safety profile in the majority of patients. We report the case of a patient who was hospitalised with muscle pain, deteriorating mobility and multiple fractures following repeated ferric carboxymaltose infusions. Investigations revealed severe hypophosphatemia with serum phosphate of 0.27 mmol/L, 25-hydroxyvitamin D (25OHD) level of 32 nmol/L and insufficiency fractures of the sacrum and L5 transverse process. The patient's hypophosphatemia was corrected with several infusions of intravenous phosphate, as well as oral phosphate and calcitriol, with subsequent resolution of her muscle aches, back pain and immobility. The risk of persistent hypophosphatemia and osteomalacia may be higher with iron carboxymaltose than other iron formulations and a transient increase in intact fibroblast growth factor-23 with reduced renal tubular phosphate absorption has been postulated as the key mechanism. This risk appears increased by repeated iron infusions, underlying malnutrition, hypophosphatemia at baseline, vitamin D deficiency, hyperparathyroidism or anti-resorptive medication use. The true risk and incidence of hypophosphatemia need to be clarified so that appropriate monitoring, prevention and treatment strategies can be developed.

Endocuff Vision is safe to use for dysplasia surveillance in patients with ulcerative colitis: a feasibility study.

Background and study aims Endocuff Vision improves adenoma detection rates in patients without inflammatory bowel disease. This study aimed to investigate the safety and feasibility of Endocuff Vision-assisted high-definition white light endoscopy (HDWLE) with dye-spray chromoendoscopy for detection of dysplasia in patients with ulcerative colitis. Patients and methods Patients with clinically inactive ulcerative colitis due for dysplasia surveillance were recruited. Procedural endpoints included safety, cecal intubation rate (CIR), terminal ileum intubation rate (TIR), withdrawal time, polyp detection rate, dysplasia detection rate (DDR), and sessile serrated lesion detection rate. Results Twenty-five patients (9 female, median age 57 [range 28 - 82] years) were studied. Endocuff Vision-assisted HDWLE was completed in all participants, with a CIR of 100 %, in a median 4 minutes (range 2 - 16), and a TIR of 88% in a median of 6.5 minutes (range 3 - 19). Median withdrawal time was 18 minutes (range 10 - 55), including application of dye-spray, biopsies and polypectomy. The Mayo Endoscopic subscore was 0 in 11, 1 in 9, and 2 in 5 patients. The DDR was 24 % (6 patients had a total of 12 dysplastic lesions) and sessile serrated lesion detection rate was 12 % (3 patients had a total of 4 sessile serrated polyps). No serious adverse events occurred, with one patient developing clinically insignificant minor mucosal bleeding. Conclusion Endocuff Vision-assisted HDWLE is feasible and safe in patients with ulcerative colitis undergoing dysplasia surveillance. Further studies are required to assess superiority of this technique compared with standard high-definition white light endoscopy with chromoendoscopy.

Drug-induced liver injury is frequently associated with severe cutaneous adverse drug reactions: experience from two Australian tertiary hospitals.

BACKGROUND: Drug-induced liver injury (DILI) can be associated with certain cutaneous adverse drug reaction (cADR). AIMS: To demonstrate the prevalence of DILI in patients with cADRs. Severity and patterns of liver injury, risk factors, causal medications and outcomes are also examined. METHODS: A retrospective cohort study of patients with cADRs was conducted across two hospitals in Australia. Patients were identified through cross-linkage of multiple databases. RESULTS: One hundred and four patients with cADRs were identified. Of these, 33 (31.7%) had liver injury, representing 50% of patients with drug reaction with eosinophilia and systemic symptoms, and 30.2% of patients with Stevens-Johnson syndrome (SJS)/toxic epidermal necrolysis (TEN). Most cases of liver injury (69.7%) were of a cholestatic/mixed pattern with severe disease in 18.2%. No significant risk factors for development of liver injury were noted, but peripheral lymphocytosis may represent a risk in patients with SJS (odds ratio, OR = 6.0, 95% confidence interval, CI: 1.8-19.7, P = 0.003). Antimicrobials were the most common class to be implicated in DILI. The median length of inpatient stay was longer in patients with liver injury compared to those without (19 vs 11 days, P = 0.002). The mortality rate in those with liver injury was 15.2% and 9.9% in those without. No patients required liver transplantation. CONCLUSIONS: DILI commonly occurs in patients with cADRs and is associated with longer inpatient stay. Patients with SJS/TEN and peripheral lymphocytosis appear to be at higher risk for developing associated liver injury.

Comparison of Caffeine and d-amphetamine in Cocaine-Dependent Subjects: Differential Outcomes on Subjective and Cardiovascular Effects, Reward Learning, and Salivary Paraxanthine.

Due to indirect modulation of dopamine transmission, adenosine receptor antagonists may be useful in either treating cocaine use or improving disrupted cognitive-behavioral functions associated with chronic cocaine use. To compare and contrast the stimulant effects of adenosine antagonism to direct dopamine stimulation, we administered 150 mg and 300 mg caffeine, 20 mg amphetamine, and placebo to cocaine-dependent vs. healthy control subjects, matched on moderate caffeine use. Data were obtained on measures of cardiovascular effects, subjective drug effects (ARCI, VAS, DEQ), and a probabilistic reward-learning task sensitive to dopamine modulation. Levels of salivary caffeine and the primary caffeine metabolite paraxanthine were obtained on placebo and caffeine dosing days. Cardiovascular results revealed main effects of dose for diastolic blood pressure and heart rate; follow up tests showed that controls were most sensitive to 300 mg caffeine and 20 mg amphetamine; cocaine-dependent subjects were sensitive only to 300 mg caffeine. Subjective effects results revealed dose × time and dose × group interactions on the ARCI A, ARCI LSD, and VAS 'elated' scales; follow up tests did not show systematic differences between groups with regard to caffeine or d-amphetamine. Large between-group differences in salivary paraxanthine (but not salivary caffeine) levels were obtained under both caffeine doses. The cocaine-dependent group expressed significantly higher paraxanthine levels than controls under 150 mg and 3-4 fold greater levels under 300 mg at 90 min and 150 min post caffeine dose. However, these differences also covaried with cigarette smoking status (not balanced between groups), and nicotine smoking is known to alter caffeine/paraxanthine metabolism via cytochrome P450 enzymes. These preliminary data raise the possibility that adenosine antagonists may affect cocaine-dependent and non-dependent subjects differently. In conjunction with previous preclinical and human studies, the data suggest that adenosine modulating drugs may have value in the treatment of stimulant use disorders.

Notch activation inhibits AML growth and survival: a potential therapeutic approach.

Although aberrant Notch activation contributes to leukemogenesis in T cells, its role in acute myelogenous leukemia (AML) remains unclear. Here, we report that human AML samples have robust expression of Notch receptors; however, Notch receptor activation and expression of downstream Notch targets are remarkably low, suggesting that Notch is present but not constitutively activated in human AML. The functional role of these Notch receptors in AML is not known. Induced activation through any of the Notch receptors (Notch1-4), or through the Notch target Hairy/Enhancer of Split 1 (HES1), consistently leads to AML growth arrest and caspase-dependent apoptosis, which are associated with B cell lymphoma 2 (BCL2) loss and enhanced p53/p21 expression. These effects were dependent on the HES1 repressor domain and were rescued through reexpression of BCL2. Importantly, activated Notch1, Notch2, and HES1 all led to inhibited AML growth in vivo, and Notch inhibition via dnMAML enhanced proliferation in vivo, thus revealing the physiological inhibition of AML growth in vivo in response to Notch signaling. As a novel therapeutic approach, we used a Notch agonist peptide that led to significant apoptosis in AML patient samples. In conclusion, we report consistent Notch-mediated growth arrest and apoptosis in human AML, and propose the development of Notch agonists as a potential therapeutic approach in AML.

The combination of the novel glycolysis inhibitor 3-BrOP and rapamycin is effective against neuroblastoma.

Children with high-risk and recurrent neuroblastoma have poor survival rates, and novel therapies are needed. Many cancer cells have been found to preferentially employ the glycolytic pathway for energy generation, even in the presence of oxygen. 3-BrOP is a novel inhibitor of glycolysis, and has demonstrated efficacy against a wide range of tumor types. To determine whether human neuroblastoma cells are susceptible to glycolysis inhibition, we evaluated the role of 3-BrOP in neuroblastoma model systems. Neuroblastoma tumor cell lines demonstrated high rates of lactate accumulation and low rates of oxygen consumption, suggesting a potential susceptibility to inhibitors of glycolysis. In all ten human tested neuroblastoma tumor cell lines, 3-BrOP induced cell death via apoptosis in a dose and time dependent manner. Furthermore, 3-BrOP-induced depletion of ATP levels correlated with decreased neuroblastoma cell viability. In a mouse neuroblastoma xenograft model, glycolysis inhibition with 3-BrOP demonstrated significantly reduced final tumor weight. In neuroblastoma tumor cells, treatment with 3-BrOP induced mTOR activation, and the combination of 3-BrOP and mTOR inhibition with rapamycin demonstrated synergistic efficacy. Based on these results, neuroblastoma tumor cells are sensitive to treatment with inhibitors of glycolysis, and the demonstrated synergy with rapamycin suggests that the combination of glycolysis and mTOR inhibitors represents a novel therapeutic approach for neuroblastoma that warrants further investigation.

Notch pathway activation induces neuroblastoma tumor cell growth arrest.

BACKGROUND: Notch pathway signaling has critical roles in differentiation, proliferation, and survival, and has oncogenic or tumor suppressor effects in a variety of malignancies. The goal of this study was to evaluate the effects of Notch activation on human neuroblastoma cells. PROCEDURE: Quantitative RT-PCR, immunoblots, and immunohistochemistry were used to determine the expression of Notch receptors (Notch1-4), cleaved Notch1 (ICN1), and downstream targets (HES1-5) in human neuroblastoma cell lines and patient tumor samples. Notch pathway signaling was induced using intracellular Notch (ICN1-3) and HES gene constructs or direct culture on Notch ligands. Quantitative methylation-specific PCR was used to quantify methylation of the HES gene promoters, and the effects of treatment with decitabine were measured. RESULTS: Neuroblastoma cells express varying levels of Notch receptors and low levels of HES genes at baseline. However, no endogenous activation of the Notch pathway was detected in neuroblastoma cell lines or patient tumor samples. Expression of activated Notch intracellular domains and HES gene products led to growth arrest. The HES2 and HES5 gene promoters were found to be heavily methylated in most neuroblastoma lines, and HES gene expression could be induced through treatment with decitabine. CONCLUSIONS: We report that neuroblastoma cell lines express multiple Notch receptors, which are inactive at baseline. Activation of the Notch pathway via ligand binding consistently resulted in growth arrest. HES gene expression appears to be regulated epigenetically and could be induced with decitabine. These findings support a tumor suppressor role for Notch signaling in neuroblastoma.

Pronounced hypoxia in models of murine and human leukemia: high efficacy of hypoxia-activated prodrug PR-104.

Recent studies indicate that interactions between leukemia cells and the bone marrow (BM) microenvironment promote leukemia cell survival and confer resistance to anti-leukemic drugs. There is evidence that BM microenvironment contains hypoxic areas that confer survival advantage to hematopoietic cells. In the present study we investigated whether hypoxia in leukemic BM contributes to the protective role of the BM microenvironment. We observed a marked expansion of hypoxic BM areas in immunodeficient mice engrafted with acute lymphoblastic leukemia (ALL) cells. Consistent with this finding, we found that hypoxia promotes chemoresistance in various ALL derived cell lines. These findings suggest to employ hypoxia-activated prodrugs to eliminate leukemia cells within hypoxic niches. Using several xenograft models, we demonstrated that administration of the hypoxia-activated dinitrobenzamide mustard, PR-104 prolonged survival and decreased leukemia burden of immune-deficient mice injected with primary acute lymphoblastic leukemia cells. Together, these findings strongly suggest that targeting hypoxia in leukemic BM is feasible and may significantly improve leukemia therapy.

Targeting glycolysis in leukemia: a novel inhibitor 3-BrOP in combination with rapamycin.

Rapidly proliferating solid tumor cells are often dependent on glycolysis for ATP production even in normoxia (the Warburg effect), however it is not yet clear whether acute leukemias have a similarly increased dependence on aerobic glycolysis. We report that all acute leukemia subtypes (pre-B ALL, T-ALL and AML) demonstrated growth arrest and cell death when treated the novel glycolysis inhibitor 3-BrOP. Potentiated ATP depletion and pro-apoptotic effects were seen for 3-BrOP combinations with the cytochrome-c-reductase inhibitor antimycin A and the mTOR inhibitor rapamycin. These results reveal a potential role for glycolysis inhibition in acute leukemia subtypes and suggest potential combinations.

Notch/HES1-mediated PARP1 activation: a cell type-specific mechanism for tumor suppression.

Notch signaling plays both oncogenic and tumor suppressor roles, depending on cell type. In contrast to T-cell acute lymphoblastic leukemia (ALL), where Notch activation promotes leukemogenesis, induction of Notch signaling in B-cell ALL (B-ALL) leads to growth arrest and apoptosis. The Notch target Hairy/Enhancer of Split1 (HES1) is sufficient to reproduce this tumor suppressor phenotype in B-ALL; however, the mechanism is not yet known. We report that HES1 regulates proapoptotic signals by the novel interacting protein Poly ADP-Ribose Polymerase1 (PARP1) in a cell type-specific manner. Interaction of HES1 with PARP1 inhibits HES1 function, induces PARP1 activation, and results in PARP1 cleavage in B-ALL. HES1-induced PARP1 activation leads to self-ADP ribosylation of PARP1, consumption of nicotinamide adenine dinucleotide(+), diminished adenosine triphosphate levels, and translocation of apoptosis-inducing factor from mitochondria to the nucleus, resulting in apoptosis in B-ALL but not T-cell ALL. Importantly, induction of Notch signaling by the Notch agonist peptide Delta/Serrate/Lag-2 can reproduce these events and leads to B-ALL apoptosis. The novel interaction of HES1 and PARP1 in B-ALL modulates the function of the HES1 transcriptional complex and signals through PARP1 to induce apoptosis. This mechanism shows a cell type-specific proapoptotic pathway that may lead to Notch agonist-based cancer therapeutics.

The selective Trk inhibitor AZ623 inhibits brain-derived neurotrophic factor-mediated neuroblastoma cell proliferation and signaling and is synergistic with topotecan.

BACKGROUND: TrkB expression is associated with poor prognosis for patients with neuroblastoma. AZ623 is a novel potent and selective inhibitor of the Trk family of tyrosine kinases. The authors hypothesized that AZ623 would inhibit TrkB-mediated signaling in neuroblastoma tumor cells and would be synergistic when combined with chemotherapy. METHODS: Neuroblastoma cell lines were screened for TrkB receptor mRNA expression and for their proliferation rates in response to brain-derived neurotrophic factor (BDNF). The effects of AZ623 on Trk receptor phosphorylation, signaling, and cell growth were evaluated in BDNF-treated neuroblastoma cells. Mice with human neuroblastoma xenograft tumors were treated with AZ623 alone and in combination with topotecan, and tumor growth rates were determined during and after treatment. RESULTS: Neuroblastoma cell lines expressed various levels of the TrkB receptor and demonstrated increased proliferation in response to BDNF. BDNF treatment stimulated TrkB phosphorylation and downstream signaling that could be inhibited by AZ623. Neuroblastoma cells demonstrated in vitro sensitivity to AZ623, with concentration that inhibits 50% (IC50) values between 0.8 to 7 µM. AZ623 treatment was found to inhibit BDNF-mediated neuroblastoma cell proliferation. Mice with human neuroblastoma xenograft tumors demonstrated tumor growth inhibition when treated with AZ623 and with AZ623 combined with topotecan. Limited tumor regrowth was noted in mice with tumors treated with AZ623 combined with topotecan after treatment discontinuation. CONCLUSIONS: AZ623 is a novel selective Trk inhibitor that inhibits BDNF-mediated signaling and neuroblastoma cell proliferation. AZ623 treatment inhibits the growth of human neuroblastoma xenograft tumors, and treatment with AZ623 combined with topotecan results in the prolonged inhibition of tumor regrowth. On the basis of these results, further preclinical development is warranted.

A novel therapeutic combination for neuroblastoma: the vascular endothelial growth factor receptor/epidermal growth factor receptor/rearranged during transfection inhibitor vandetanib with 13-cis-retinoic acid.

BACKGROUND: High-risk cases of neuroblastoma have poor survival rates, and novel therapies are needed. Vandetanib (ZD6474, Zactima) is an inhibitor of the vascular endothelial growth factor receptor, epidermal growth factor receptor, and rearranged during transfection (RET) tyrosine kinases, which have each been implicated in neuroblastoma pathogenesis. The authors hypothesized that vandetanib combined with 13-cis-retinoic acid (CRA), a differentiating agent used in most current neuroblastoma treatment regimens, would be effective against neuroblastoma tumor models. METHODS: The authors evaluated the effects of vandetanib with and without CRA on RET phosphorylation and on the proliferation and survival of human neuroblastoma cell lines in vitro. Using a subcutaneous mouse xenograft model of human neuroblastoma, they analyzed tumors treated with CRA, vandetanib, and the combination of vandetanib plus CRA for growth, gross and histologic appearance, vascularity, and apoptosis. RESULTS: Vandetanib treatment inhibited RET phosphorylation and resulted in induction of apoptosis in the majority of neuroblastoma cell lines in vitro, whereas CRA treatment induced morphologic differentiation and cell-cycle arrest. Treatment with vandetanib plus CRA resulted in more significant reduction in neuroblastoma cell viability than either alone. In a mouse xenograft model, the combination of vandetanib with CRA demonstrated significantly more growth inhibition than either alone, via both reduction in tumor vascularity and induction of apoptosis. CONCLUSIONS: Vandetanib induces neuroblastoma tumor cell death in vitro and reduces tumor growth and vascularity in vivo. The combination of vandetanib with CRA was more effective in reducing tumor growth than either treatment alone. The antitumor effects of vandetanib plus CRA suggest a novel combination for use in neuroblastoma patients.