Cancer stem cells (CSCs) proliferate extensively and drive tumor metastasis and recurrence. CSCs have been identified in over 20 cancer types to date, but it remains unknown how to target and eliminate CSCs in vivo. Aldehyde dehydrogenase (ALDH) is a marker that has been used extensively for isolating CSCs. Here we present a novel approach to target and reduce the frequency of ALDH high CSCs by vaccination against ALDH. We have identified ALDH1-A1 and ALDH1-A3 epitopes from CSCs and developed synthetic high-density lipoprotein nanodiscs for vaccination against ALDH high CSCs. Nanodiscs increased antigen trafficking to lymph nodes and generated robust ALDH-specific T cell responses. Nanodisc vaccination against ALDH high CSCs combined with anti-PD-L1 therapy exerted potent antitumor efficacy and prolonged animal survival in multiple murine models. Overall, this is the first demonstration of a simple nanovaccine strategy against CSCs and may lead to new avenues for cancer immunotherapy against CSCs.

Objective Aptamers are oligonucleotides targeting protein/protein interactions with pharmacokinetic profiles and activity reversal options. Although P-selectin and von Willebrand factor (VWF) have been implicated in the development of venous thrombosis (VT), no studies have directly compared aptamer efficacy with standard of care in VT. In this study, ARC5692, an anti-P-selectin aptamer, and ARC15105, an anti- VWF aptamer, were compared to low molecular weight heparin, enoxaparin, to test the efficacy of P-selectin or VWF inhibition in promoting thrombus resolution and preventing vein wall fibrosis, in a baboon model of VT. Approach and Results Groups: Treatment arm: Animals received P-selectin or VWF aptamer inhibitors or enoxaparin (n=3 per group). Controls received no treatment (n=3). Prophylactic arm: Animals received P-selectin inhibitor (n=4) or VWF inhibitor (n=3). Treatment arm: P-selectin-inhibitor demonstrated a significant improvement in vein recanalization by MRV (73% at day 21), and significantly decreased vein wall collagen, compared to all groups. Anti-P-selectin equaled enoxaparin in maintaining valve competency by ultrasound. All control animals had compromised valve competency post-thrombosis. Prophylactic arm: animals receiving P-selectin and VWF inhibitors demonstrated improved vein recanalization by MRV versus controls (80% and 85% respectively at day 21). Anti-P-selectin protected iliac valve function better than anti-VWF, and both improved valve function versus controls. No adverse bleeding events were observed. Conclusions The P-selectin inhibitor aptamer promoted iliac vein recanalization, preserved valve competency and decreased vein wall fibrosis. The results of this work suggest that P-selectin inhibition maybe an ideal target in the treatment and prophylaxis of DVT, warranting clinical trials.

Compassion Fatigue (CF) is commonly observed in professions associated with human and animal care. The COVID-19 pandemic compelled laboratory animal research institutions to implement new work practices in order to maintain essential animal care operations. These modifications ranged from shift changes to last-resort measures, such as culling animal colonies, to accommodate reduced staffing. Such changes could cause personnel to experience increased stress, isolation, and helplessness—all of which can increase CF risk. In the current study, 200 persons involved with animal research completed an online survey to gauge whether CF among laboratory animal personnel had increased during the pandemic. The survey examined professional quality of life, self-assessed levels of CF, institutional changes, perceived changes in animal welfare, and institutional measures intended to alleviate CF. A total of 86% of participants had experienced CF at some point in their career, with 41% experiencing a CF event (new or worsening symptoms of CF) during the pandemic. In addition, 90% of participants who reported a CF event also reported subsequent effects on their personal or professional lives. Health, employment, and animal-related stress that arose due to the pandemic were all found to influence CF scores significantly. Although 96% of respondents were considered essential workers, 67% did not feel as valued for their work as other essential personnel. Furthermore, 88% of personnel responsible for the euthanasia of healthy animals who experienced a CF event reported that CF also affected their personal life, professional life, or both, and 78% responded that interventions from internal CF programs or leadership did not help to alleviate symptoms of CF. The COVID-19 pandemic and resultant institutional changes will likely have lasting effects on persons and organizations. By determining and subsequently mitigating sources of CF, we can better assist the laboratory animal community during future crises.

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