Prioritizing interventions for preventing COVID-19 outbreaks in military basic training.

Like other congregate living settings, military basic training has been subject to outbreaks of COVID-19. We sought to identify improved strategies for preventing outbreaks in this setting using an agent-based model of a hypothetical cohort of trainees on a U.S. Army post. Our analysis revealed unique aspects of basic training that require customized approaches to outbreak prevention, which draws attention to the possibility that customized approaches may be necessary in other settings, too. In particular, we showed that introductions by trainers and support staff may be a major vulnerability, given that those individuals remain at risk of community exposure throughout the training period. We also found that increased testing of trainees upon arrival could actually increase the risk of outbreaks, given the potential for false-positive test results to lead to susceptible individuals becoming infected in group isolation and seeding outbreaks in training units upon release. Until an effective transmission-blocking vaccine is adopted at high coverage by individuals involved with basic training, need will persist for non-pharmaceutical interventions to prevent outbreaks in military basic training. Ongoing uncertainties about virus variants and breakthrough infections necessitate continued vigilance in this setting, even as vaccination coverage increases.

Virological and Serological Assessment of US Army Trainees Isolated for Coronavirus Disease 2019.

BACKGROUND: Laboratory screening for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is a key mitigation measure to avoid the spread of infection among recruits starting basic combat training in a congregate setting. Because viral nucleic acid can be detected persistently after recovery, we evaluated other laboratory markers to distinguish recruits who could proceed with training from those who were infected. METHODS: Recruits isolated for coronavirus disease 2019 (COVID-19) were serially tested for SARS-CoV-2 subgenomic ribonucleic acid (sgRNA), and viral load (VL) by reverse-transcriptase polymerase chain reaction (RT-PCR), and for anti- SARS-CoV-2. Cluster and quadratic discriminant analyses of results were performed. RESULTS: Among 229 recruits isolated for COVID-19, those with a RT-PCR cycle threshold >30.49 (sensitivity 95%, specificity 96%) or having sgRNA log10 RNA copies/mL <3.09 (sensitivity and specificity 96%) at entry into isolation were likely SARS-CoV-2 uninfected. Viral load >4.58 log10 RNA copies/mL or anti-SARS-CoV-2 signal-to-cutoff ratio <1.38 (VL: sensitivity and specificity 93%; anti-SARS-CoV-2: sensitivity 83%, specificity 79%) had comparatively lower sensitivity and specificity when used alone for discrimination of infected from uninfected. CONCLUSIONS: Orthogonal laboratory assays used in combination with RT-PCR may have utility in determining SARS-CoV-2 infection status for decisions regarding isolation.

hnRNP K supports the maintenance of RORγ circadian rhythm through ERK signaling.

Retinoic acid-related orphan receptor γ (RORγ) maintains the circadian rhythms of its downstream genes. However, the mechanism behind the transcriptional activation of RORγ itself remains unclear. Here, we demonstrate that transcription of RORγ is activated by heterogeneous nuclear ribonucleoprotein K (hnRNP K) via the poly(C) motif within its proximal promoter. Interestingly, we confirmed the binding of endogenous hnRNP K within RORγ1 and RORγ2 promoter along with the recruitment of RNA polymerase 2 through chromatin immunoprecipitation (ChIP). Furthermore, an assay for transposase accessible chromatin (ATAC)-qPCR showed that hnRNP K induced higher chromatin accessibility within the RORγ1 and RORγ2 promoter. Then we found that the knockdown of hnRNP K lowers RORγ mRNA oscillation amplitude in both RORγ and RORγ-dependent metabolic genes. Moreover, we demonstrated that time-dependent extracellular signal-regulated kinase (ERK) activation controls mRNA oscillation of RORγ and RORγ-dependent metabolic genes through hnRNP K. Taken together, our results provide new insight into the regulation of RORγ by hnRNP K as a transcriptional activator, along with its physiological significance in metabolism.

Isoprocurcumenol Supports Keratinocyte Growth and Survival through Epidermal Growth Factor Receptor Activation.

Although proliferation of keratinocytes, a major type of skin cells, is a key factor in maintaining the function of skin, their ability to proliferate tends to diminish with age. To solve such a problem, researchers in medical and skin cosmetic fields have tried to utilize epidermal growth factor (EGF), but achieved limited success. Therefore, a small natural compound that can mimic the activity of EGF is highly desired in both medical and cosmetic fields. Here, using the modified biosensor system, we observed that natural small-compound isoprocurcumenol, which is a terpenoid molecule derived from turmeric, can activate EGFR signaling. It increased the phosphorylation of ERK and AKT, and upregulated the expression of genes related to cell growth and proliferation, such as c-myc, c-jun, c-fos, and egr-1. In addition, isoprocurcumenol induced the proliferation of keratinocytes in both physical and UVB-induced cellular damage, indicative of its function in skin regeneration. These findings reveal that EGF-like isoprocurcumenol promotes the proliferation of keratinocytes and further suggest its potential as an ingredient for medical and cosmetics use.

Phase 2 trial of a neurokinin-1 receptor antagonist for the treatment of chronic itch in patients with epidermolysis bullosa: A randomized clinical trial.

BACKGROUND: Chronic pruritus causes major morbidity in epidermolysis bullosa (EB). The substance P-neurokinin 1 receptor (SP-NK1) pathway is a promising target for treating EB-related pruritus. OBJECTIVE: To evaluate the safety and efficacy of the oral NK1 receptor antagonist serlopitant in treating moderate-severe pruritus in EB. METHODS: The study randomized 14 patients to serlopitant or placebo for 8 weeks, followed by a 4-week washout and optional open-label extension. The primary end point was change in itch as measured by the Numeric Rating Scale. Secondary end points were change in itch during dressing changes and wound size. RESULTS: We observed greater itch reduction with serlopitant, equivalent to a 0.64-point comparative reduction on the 11-point Numeric Rating Scale by week 8, although this failed to meet statistical significance (P = .11). More serlopitant patients achieved ≥3-point reduction compared with placebo (43% vs 14%, P = .35). In post hoc analysis excluding 1 patient with a concurrent seborrheic dermatitis flare, serlopitant achieved significantly greater median itch reduction from baseline by week 4 (-2 points vs 0, P = .01). We observed no statistically significant differences in secondary end points. Serlopitant was well-tolerated. LIMITATIONS: Small sample size due to disease rarity. CONCLUSION: The potential itch reduction with serlopitant observed in this trial will be pursued by a larger powered trial (NCT03836001).

High-throughput identification of factors promoting neuronal differentiation of human neural progenitor cells in microscale 3D cell culture.

Identification of conditions for guided and specific differentiation of human stem cell and progenitor cells is important for continued development and engineering of in vitro cell culture systems for use in regenerative medicine, drug discovery, and human toxicology. Three-dimensional (3D) and organotypic cell culture models have been used increasingly for in vitro cell culture because they may better model endogenous tissue environments. However, detailed studies of stem cell differentiation within 3D cultures remain limited, particularly with respect to high-throughput screening. Herein, we demonstrate the use of a microarray chip-based platform to screen, in high-throughput, individual and paired effects of 12 soluble factors on the neuronal differentiation of a human neural progenitor cell line (ReNcell VM) encapsulated in microscale 3D Matrigel cultures. Dose-response analysis of selected combinations from the initial combinatorial screen revealed that the combined treatment of all-trans retinoic acid (RA) with the glycogen synthase kinase 3 inhibitor CHIR-99021 (CHIR) enhances neurogenesis while simultaneously decreases astrocyte differentiation, whereas the combined treatment of brain-derived neurotrophic factor and the small azide neuropathiazol enhances the differentiation into neurons and astrocytes. Subtype specification analysis of RA- and CHIR-differentiated cultures revealed that enhanced neurogenesis was not biased toward a specific neuronal subtype. Together, these results demonstrate a high-throughput screening platform for rapid evaluation of differentiation conditions in a 3D environment, which will aid the development and application of 3D stem cell culture models.

Serlopitant reduced pruritus in patients with prurigo nodularis in a phase 2, randomized, placebo-controlled trial.

BACKGROUND: Anecdotal evidence suggests that neurokinin 1 receptor antagonism reduces pruritus intensity in chronic pruritic conditions such as prurigo nodularis (PN). OBJECTIVE: This study assessed safety and efficacy of the neurokinin 1 receptor antagonist serlopitant for treatment of pruritus in PN. METHODS: In this randomized, double-blind, placebo-controlled study, 128 patients with chronic, treatment-refractory PN for more than 6 weeks received serlopitant, 5 mg, or placebo orally once daily for 8 weeks. The primary end point was change in average itch visual analog scale score at weeks 4 and 8. RESULTS: Average itch visual analog scale scores significantly improved with serlopitant versus with placebo at weeks 4 and 8: the least squares mean difference (serlopitant minus placebo) was -1.0 at week 4 (P = .02) and -1.7 at week 8 (P < .001). The least squares mean difference between serlopitant and placebo reached statistical significance at week 2 (-0.9 [P = .011]). The most frequently reported treatment-emergent adverse events in the serlopitant group were nasopharyngitis, diarrhea, and fatigue. LIMITATIONS: The 8-week duration may be insufficient to assess clinically relevant resolution of PN lesions. CONCLUSIONS: Serlopitant reduced pruritus in patients with treatment-refractory PN and was well tolerated.

3D-cultured neural stem cell microarrays on a micropillar chip for high-throughput developmental neurotoxicology.

Numerous chemicals including environmental toxicants and drugs have not been fully evaluated for developmental neurotoxicity. A key gap exists in the ability to predict accurately and robustly in vivo outcomes based on in vitro assays. This is particularly the case for predicting the toxicity of chemicals on the developing human brain. A critical need for such in vitro assays is choice of a suitable model cell type. To that end, we have performed high-throughput in vitro assessment of proliferation and differentiation of human neural stem cells (hNSCs). Conventional in vitro assays typically use immunofluorescence staining to quantify changes in cell morphology and expression of neural cell-specific biomarkers, which is often time-consuming and subject to variable specificities of available antibodies. To alleviate these limitations, we developed a miniaturized, three-dimensional (3D) hNSC culture with ReNcell VM on microarray chip platforms and established a high-throughput promoter-reporter assay system using recombinant lentiviruses on hNSC spheroids to assess cell viability, self-renewal, and differentiation. Optimum cell viability and spheroid formation of 3D ReNcell VM culture were observed on a micropillar chip over a period of 9 days in a mixture of 0.75% (w/v) alginate and 1 mg/mL growth factor reduced (GFR) Matrigel with 25 mM CaCl2 as a crosslinker for alginate. In addition, 3D ReNcell VM culture exhibited self-renewal and differentiation on the microarray chip platform, which was efficiently monitored by enhanced green fluorescent protein (EGFP) expression of four NSC-specific biomarkers including sex determining region Y-box 2 (SOX2), glial fibrillary acidic protein (GFAP), synapsin1, and myelin basic protein (MBP) with the promoter-reporter assay system.

Prevalence of Human Papillomavirus Genotypes and Abnormal Pap Smears Among Women in the Military Health System.

Human papillomavirus infection (HPV) is the most common sexually transmitted infection among United States Military Servicemembers, and present in the majority of cervical cancers. Many of these infections are preventable, but HPV immunization is not mandatory during military service. The objective of this study was to examine the prevalence of vaccine-preventable cervical disease among women enrolled in the San Antonio Military Health System. This is a retrospective cross-sectional study of Pap smear results and HPV genotyping data among Military Servicewomen and beneficiaries. Simple descriptive statistics and logistic regression were used to assess the association between demographics, cervical pathology and high-risk HPV (hrHPV) infection. Pap smears were obtained by 16.9% of women and cervical pathology was present in 28.8% of samples. Compared to the 25-34 year group, 35-44 year-olds were more likely to have an abnormal Pap smear (OR 1.25, CI 1.05-1.50). Of the samples tested, 10.5% were positive for hrHPV. Adjusted multivariable analysis revealed that hrHPV infection was more likely among the 23-34 year group when compared to 35-44 (OR 0.50, CI 0.38-0.67), 45-54 (0.40. CI 0.28-0.59) and 55-65 year groups (0.46, CI 0.30-0.71). Active Duty Servicewomen were more likely to test positive for hrHPV when compared to Active Duty Family Members (OR 0.59, CI 0.45-0.79) and Retiree Family Members (OR 0.59, CI 0.41-0.83). Younger women and Active Duty Servicewomen are significantly more likely to have cervical infection with hrHPV. Future studies should assess the cost-effectiveness of mandatory HPV immunization for military members.

Night shift work and lung cancer risk among female textile workers in Shanghai, China.

In 2007, the International Agency for Research on Cancer classified shift work that involves circadian disruption as a probable human carcinogen. Suppression of the anti-neoplastic hormone, melatonin, is a presumed mechanism of action. We conducted a case-cohort study nested within a cohort of 267,400 female textile workers in Shanghai, China. Newly diagnosed lung cancer cases (n = 1451) identified during the study period (1989-2006) were compared with an age-stratified subcohort (n = 3040). Adjusting for age, smoking, parity, and endotoxin exposure, relative risks [hazard ratios (HRs)] were estimated by Cox regression modeling to assess associations with cumulative years and nights of rotating shift work. Results did not consistently reveal any increased risk of lung cancer among rotating shift work or statistically significant trends for both cumulative years (HR 0.82, 95% CI 0.66 to 1.02; P(trend) = 0.294) and nights (HR 0.81, 95% CI 0.65 to 1.00; P(trend) = 0.415). Further analyses imposing 10- and 20-year lag times for disease latency also revealed similar results. Contrary to the initial hypothesis, rotating nighttime shift work appears to be associated with a relatively reduced lung cancer risk although the magnitude of the effect was modest and not statistically significant.

Revolutionizing Combat Casualty Care: The Power of Digital Twins in Optimizing Casualty Care Through Passive Data Collection.

The potential impact of large-scale combat operations and multidomain operations against peer adversaries poses significant challenges to the Military Health System including large volumes of critically ill and injured casualties, prolonged care times in austere care contexts, limited movement, contested logistics, and denied communications. These challenges contribute to the probability of higher casualty mortality and risk that casualty care hinders commanders' forward momentum or opportunities for overmatch on the battlefield. Novel technical solutions and associated concepts of operation that fundamentally change the delivery of casualty care are necessary to achieve desired medical outcomes that include maximizing Warfighter battle-readiness, minimizing return-to-duty time, optimizing medical evacuation that clears casualties from the battlefield while minimizing casualty morbidity and mortality, and minimizing resource consumption across the care continuum. These novel solutions promise to "automate" certain aspects of casualty care at the level of the individual caregiver and the system level, to unburden our limited number of providers to do more and make better (data-driven) decisions. In this commentary, we describe concepts of casualty digital twins-virtual representations of a casualty's physical journey through the roles of care-and how they, combined with passive data collection about casualty status, caregiver actions, and real-time resource use, can lead to human-machine teaming and increasing automation of casualty care across the care continuum while maintaining or improving outcomes. Our path to combat casualty care automation starts with mapping and modeling the context of casualty care in realistic environments through passive data collection of large amounts of unstructured data to inform machine learning models. These context-aware models will be matched with patient physiology models to create casualty digital twins that better predict casualty needs and resources required and ultimately inform and accelerate decision-making across the continuum of care. We will draw from the experience of the automotive industry as an exemplar for achieving automation in health care and inculcate automation as a mechanism for optimizing the casualty care survival chain.

Resilience in lesbian, gay, and bisexual individuals.

To promote psychological health among lesbian, gay, and bisexual (LGB) individuals, more comprehensive research on resilience factors in LGB individuals is needed. This article presents a theoretical framework based on the existing literature, with an eye toward guiding future research in this area. Social support clearly serves as a resilience factor for LGB individuals, in part through its ability to lower reactivity to prejudice. Social support is particularly effective when it specifically supports people's sexual orientation and is congruent with individuals' developmental needs. The ability to accept emotions and to process them in an insightful manner also buffers the negative impact of prejudice. In addition, hope and optimism allow LGB individuals to maintain psychological health when faced with prejudice.

Suramin binds and inhibits infection of SARS-CoV-2 through both spike protein-heparan sulfate and ACE2 receptor interactions.

SARS-CoV-2 receptor binding domains (RBDs) interact with both the ACE2 receptor and heparan sulfate on the surface of host cells to enhance SARS-CoV-2 infection. We show that suramin, a polysulfated synthetic drug, binds to the ACE2 receptor and heparan sulfate binding sites on the RBDs of wild-type, Delta, and Omicron variants. Specifically, heparan sulfate and suramin had enhanced preferential binding for Omicron RBD, and suramin is most potent against the live SARS-CoV-2 Omicron variant (B.1.1.529) when compared to wild type and Delta (B.1.617.2) variants in vitro. These results suggest that inhibition of live virus infection occurs through dual SARS-CoV-2 targets of S-protein binding and previously reported RNA-dependent RNA polymerase inhibition and offers the possibility for this and other polysulfated molecules to be used as potential therapeutic and prophylactic options against COVID-19.

Detection of positional brachial plexus injury by radial arterial line during spinal exposure before neuromonitoring confirmation: a retrospective case study.

To demonstrate the potential usefulness of radial arterial line monitoring in detection of brachial plexus injury in spinal surgery. Multiple neuromonitoring modalities including SEPs, MEPs and EMG were performed for a posterior thoracicolumbar surgery. Radial arterial line (A-line) was placed on the right wrist for arterial blood pressure monitoring. Reliable ulnar nerve SEPs, hand muscle MEPs and arterial blood pressure readings were obtained after patient was placed in a prone position. A-line malfunction was noted about 15 min after incision. Loss of ulnar nerve SEPs and hand muscle MEPs with a cold hand on the right was noticed when neuromonitoring resumed after spine exposure. SEPs, MEPs, A-line readings and hand temperature returned after modification of the right arm position. Radial arterial line monitoring may help detect positional brachial plexus injury in spinal surgery when continuous neuromonitoring is interrupted during spine exposure in prone position.

Quarantine in a COVID-19 Pandemic: Lessons from a Deployed Role I.

The coronavirus (COVID-19) pandemic has changed the world; and the US military changed with it. Although this virus presents with a wide spectrum of disease progression (no symptoms to acute respiratory distress syndrome leading to death), its impact extends beyond health outcomes. At the time of this study, numerous research and development projects were underway to develop a COVID-19 vaccine or other treatment modalities; however, there were no Federal Drug Administration (FDA) approved vaccines or medical therapeutics that definitively provided a cure. Instead, public health officials relied on non-pharmaceutical interventions (NPI) as a main strategy to contain and mitigate the disease. The US military in partnership with host nation countries, such as the Kingdom of Saudi Arabia, exemplified unity of effort through a coordinated response: mass testing, prompt contact tracing, quarantine, and isolation. One main non-pharmaceutical intervention (NPI) strategy includes social distancing which has been shown to significantly impact pandemic influenza transmission translating to COVID-19 mitigation measures. In the military, strict adherence to quarantine, restriction of movement, and isolation orders can be a challenge since appropriate facilities and resources are limited in deployed and training environments. Further, asymptomatic carriage and transmission of COVID-19 disease (mean incubation time 6.2 days and range of 2-14 days) can complicate quarantine and testing methodologies. Moreover, deployment of the NPI mitigation strategies such as quarantine and isolation in an effective and timely manner is essential to prevent further spread. In essence, quarantine is the prevention, and isolation is the cure. This paper aims to describe how a deployed US Army Role I can effectively utilize NPI and containment strategies during a global pandemic in an austere environment.

Designer DNA nanostructures for viral inhibition.

Emerging viral diseases can substantially threaten national and global public health. Central to our ability to successfully tackle these diseases is the need to quickly detect the causative virus and neutralize it efficiently. Here we present the rational design of DNA nanostructures to inhibit dengue virus infection. The designer DNA nanostructure (DDN) can bind to complementary epitopes on antigens dispersed across the surface of a viral particle. Since these antigens are arranged in a defined geometric pattern that is unique to each virus, the structure of the DDN is designed to mirror the spatial arrangement of antigens on the viral particle, providing very high viral binding avidity. We describe how available structural data can be used to identify unique spatial patterns of antigens on the surface of a viral particle. We then present a procedure for synthesizing DDNs using a combination of in silico design principles, self-assembly, and characterization using gel electrophoresis, atomic force microscopy and surface plasmon resonance spectroscopy. Finally, we evaluate the efficacy of a DDN in inhibiting dengue virus infection via plaque-forming assays. We expect this protocol to take 2-3 d to complete virus antigen pattern identification from existing cryogenic electron microscopy data, ~2 weeks for DDN design, synthesis, and virus binding characterization, and ~2 weeks for DDN cytotoxicity and antiviral efficacy assays.

COVID-19 in a Role I Evacuation: A Case Series.

Since December 2019, the novel SARS-CoV-2 (severe acute respiratory syndrome coronavirus-2) became an emerging infectious disease pathogen that led to a global pandemic with over 43 million cases reported worldwide and more than 1.1 million global deaths (as of 26 Oct 2020, from https://coronavirus.jhu.edu/map.html). Commonly known as coronavirus disease 2019 (COVID-19), this pathogen presents with a broad spectrum of disease progression and manifestations (no symptoms to acute respiratory distress syndrome leading to severe complications and death).1,2 Multiple publications have reported risk of disease and co-morbidities to include select underlying medical conditions and risks: older age (≥65 years), hypertension (HTN), cardiovascular disease, smoking, chronic respiratory disease, cancer, diabetes (DM), obesity (BMI ≥ 30 kg/m2), and male sex.2,3,4,5,6,7,8 In one study, researchers found severe obesity (BMI ≥ 35 kg/m2) associated with intensive care unit (ICU) admission alone.8 Nonetheless, risk factors for severity of the disease are determined by the pathogen, host, and environment.9.

Serological and RT-PCR Surveillance for COVID-19 in an Asymptomatic US Army Trainee Population.

BACKGROUND: Significant variability exists in the application of infection control policy throughout the US Army initial entry training environment. To generate actionable information for the prevention of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)/coronavirus disease 2019 (COVID-19) transmission among new recruits, active enhanced surveillance was conducted for evidence of and exposure to SARS-CoV-2/COVID-19. METHODS: We serially tested recruits with a reverse transcriptase polymerase chain reaction (RT-PCR) COVID-19 and/or total antibody to SARS-CoV-2 tests at days 0, 14, and week 10 upon arrival for basic combat training at a location in the Southern United States. RESULTS: Among 1403 recruits who were enrolled over a 6-week period from August 25 through October 11, 2020, 84 recruits tested positive by RT-PCR, with more than half (55%, 46/84) testing positive at arrival and almost two-thirds (63%, 53/84) also testing seropositive at arrival. Similarly, among an overall 146 recruits who tested seropositive for SARS-CoV-2 during the period of observation, a majority (86%) tested seropositive at arrival; no hospitalizations were observed among seropositive recruits, and antibody response increased at week 10. CONCLUSIONS: These findings that suggest serological testing may complement current test-based measures and provide another tool to incorporate in COVID-19 mitigation measures among trainees in the US Army.

PCA062, a P-cadherin Targeting Antibody-Drug Conjugate, Displays Potent Antitumor Activity Against P-cadherin-expressing Malignancies.

The cell surface glycoprotein P-cadherin is highly expressed in a number of malignancies, including those arising in the epithelium of the bladder, breast, esophagus, lung, and upper aerodigestive system. PCA062 is a P-cadherin specific antibody-drug conjugate that utilizes the clinically validated SMCC-DM1 linker payload to mediate potent cytotoxicity in cell lines expressing high levels of P-cadherin in vitro, while displaying no specific activity in P-cadherin-negative cell lines. High cell surface P-cadherin is necessary, but not sufficient, to mediate PCA062 cytotoxicity. In vivo, PCA062 demonstrated high serum stability and a potent ability to induce mitotic arrest. In addition, PCA062 was efficacious in clinically relevant models of P-cadherin-expressing cancers, including breast, esophageal, and head and neck. Preclinical non-human primate toxicology studies demonstrated a favorable safety profile that supports clinical development. Genome-wide CRISPR screens reveal that expression of the multidrug-resistant gene ABCC1 and the lysosomal transporter SLC46A3 differentially impact tumor cell sensitivity to PCA062. The preclinical data presented here suggest that PCA062 may have clinical value for treating patients with multiple cancer types including basal-like breast cancer.

Activity of deacetylase inhibitor panobinostat (LBH589) in cutaneous T-cell lymphoma models: Defining molecular mechanisms of resistance.

Panobinostat (LBH589) is a highly potent deacetylase inhibitor that has demonstrated clinical efficacy in patients with advanced cutaneous T-cell lymphoma (CTCL). To gain a better understanding of the compound activity in this tumor type, we investigated the cellular and molecular effects of panobinostat using both in vitro and in vivo models of CTCL. All 4 tested CTCL cell lines exhibited very high sensitivity to panobinostat-induced growth inhibition. However, only 2 of 4 lines exhibited significant response to the cytotoxic activity of panobinostat. In a CTCL xenograft mouse tumor model, panobinostat treatment resulted in complete tumor regression. The difference in cell sensitivity to panobinostat-induced death enabled us to further investigate potential mechanisms responsible for tumor sensitivity or resistance. In CTCL cell lines that were insensitive to panobinostat-induced apoptosis, constitutively activated NF-kappaB and high levels of Bcl-2 were observed. Inhibition of Bcl-2 sensitized cells to the cytotoxic activity of panobinostat. Conversely, knockdown of Bax diminished the CTCL cell sensitivity. Interestingly, panobinostat could induce cytotoxicity in vorinostat-resistant CTCL cells by downregulating phosphorylated STAT3 and STAT5 proteins. These studies suggest distinct mechanisms responsible for resistance to different deacetylase inhibitors. We show that the intrinsic apoptotic signaling plays an essential role in mediating panobinostat anticancer activity. Moreover, cancer cell sensitivity to panobinostat treatment may be further improved by combination with inhibition of anti-apoptotic factors. These data provide preclinical support that panobinostat, as a single agent or in combination with other anticancer agents, is a promising therapy for CTCL.