COVID-19 affects millions of patients worldwide with clinical presentation ranging from isolated thrombosis to acute respiratory distress syndrome (ARDS) requiring ventilator support. Neutrophil extracellular traps (NETs) originate from decondensed chromatin released to immobilize pathogens and can trigger immunothrombosis. We studied the connection between NETs and COVID-19 severity and progression. We conducted a prospective cohort study of COVID-19 patients (n=33) with age- and sex-matched controls (n=17). We measured plasma myeloperoxidase (MPO)-DNA complexes (NETs), Platelet Factor 4, RANTES, and selected cytokines. Three COVID-19 lung autopsies were examined for NETs and platelet involvement. We assessed NET formation ex vivo in COVID-19 neutrophils and in healthy neutrophils incubated with COVID-19 plasma. We also tested the ability of neonatal NET-Inhibitory Factor (nNIF) to block NET formation induced by COVID-19 plasma. Plasma MPO-DNA complexes increased in COVID-19 with intubation (P<0.0001) and death as outcome (P<0.0005). Illness severity correlated directly with plasma MPO-DNA complexes (P=0.0360), while PaO2/FiO2 correlated inversely(P=0.0340). Soluble and cellular factors triggering NETs were significantly increased in COVID-19 and pulmonary autopsies confirmed NET-containing microthrombi with neutrophil-platelet infiltration. Finally, COVID-19 neutrophils ex vivo displayed excessive NETs at baseline and COVID-19 plasma triggered NET formation which was blocked by nNIF. Thus, NETs triggering immunothrombosis may, in part, explain the prothrombotic clinical presentations in COVID-19 and NETs may represent targets for therapeutic intervention.

IMPORTANCE Evolutionary medicine may provide insights into human physiology and pathophysiology, including tumor biology. OBJECTIVE To identify mechanisms for cancer resistance in elephants and compare cellular response to DNA damage among elephants, healthy human controls, and cancer-prone patients with Li-Fraumeni syndrome (LFS). DESIGN, SETTING, AND PARTICIPANTS A comprehensive survey of necropsy data was performed across 36 mammalian species to validate cancer resistance in large and long-lived organisms, including elephants (n = 644). The African and Asian elephant genomes were analyzed for potential mechanisms of cancer resistance. Peripheral blood lymphocytes from elephants, healthy human controls, and patients with LFS were tested in vitro in the laboratory for DNA damage response. The study included African and Asian elephants (n = 8), patients with LFS (n = 10), and age-matched human controls (n = 11). Human samples were collected at the University of Utah between June 2014 and July 2015. EXPOSURES Ionizing radiation and doxorubicin. MAIN OUTCOMES AND MEASURES Cancer mortality across species was calculated and compared by body size and life span. The elephant genome was investigated for alterations in cancer-related genes. DNA repair and apoptosis were compared in elephant vs human peripheral blood lymphocytes. RESULTS Across mammals, cancer mortality did not increase with body size and/or maximum life span (eg, for rock hyrax, 1% [95%CI, 0%–5%]; African wild dog, 8%[95%CI, 0%–16%]; lion, 2%[95%CI, 0% –7%]). Despite their large body size and long life span, elephants remain cancer resistant, with an estimated cancer mortality of 4.81% (95%CI, 3.14%–6.49%), compared with humans, who have 11% to 25%cancer mortality. While humans have 1 copy (2 alleles) of TP53, African elephants have at least 20 copies (40 alleles), including 19 retrogenes (38 alleles) with evidence of transcriptional activity measured by reverse transcription polymerase chain reaction. In response to DNA damage, elephant lymphocytes underwent p53-mediated apoptosis at higher rates than human lymphocytes proportional to TP53 status (ionizing radiation exposure: patients with LFS, 2.71% [95%CI, 1.93%–3.48%] vs human controls, 7.17%[95%CI, 5.91%–8.44%] vs elephants, 14.64%[95%CI, 10.91%–18.37%]; P < .001; doxorubicin exposure: human controls, 8.10% [95%CI, 6.55%–9.66%] vs elephants, 24.77%[95%CI, 23.0%–26.53%]; P < .001). CONCLUSIONS AND RELEVANCE Compared with other mammalian species, elephants appeared to have a lower-than-expected rate of cancer, potentially related to multiple copies of TP53. Compared with human cells, elephant cells demonstrated increased apoptotic response following DNA damage. These findings, if replicated, could represent an evolutionary-based approach for understanding mechanisms related to cancer suppression.

A widespread approach to modern cancer therapy is to identify a single oncogenic driver gene and target its mutant protein product (e.g. EGFR inhibitor treatment in EGFR-mutant lung cancers). However, genetically-driven resistance to targeted therapy limits patient survival. Through genomic analysis of 1122 EGFR-mutant lung cancer cell-free DNA samples and whole exome analysis of seven longitudinally collected tumor samples from an EGFR-mutant lung cancer patient, we identify critical co-occurring oncogenic events present in most advanced-stage EGFR-mutant lung cancers. We define new pathways limiting EGFR inhibitor response, including WNT/β-catenin and cell cycle gene (e.g. CDK4, CDK6) alterations. Tumor genomic complexity increases with EGFR inhibitor treatment and co-occurring alterations in CTNNB1, and PIK3CA exhibit non-redundant functions that cooperatively promote tumor metastasis or limit EGFR inhibitor response. This study challenges the prevailing single-gene driver oncogene view and links clinical outcomes to co-occurring genetic alterations in advanced-stage EGFR-mutant lung cancer patients.

The evolution of multicellularity required the suppression of cancer. If every cell has some chance of becoming cancerous, large, long-lived organisms should have an increased risk of developing cancer compared to small, short-lived organisms. The lack of correlation between body size and cancer risk is known as Peto's Paradox. Animals with 1,000 times more cells than humans do not exhibit an increased cancer risk, suggesting that natural mechanisms can suppress cancer 1,000 times more effectively than is done in human cells. Because cancer has proven difficult to cure, attention has turned to cancer prevention. In this review, like pharmaceutical companies mining natural products, we seek to understand how evolution has suppressed cancer to ultimately develop improved cancer prevention in humans.

Whales have 1000-fold more cells than humans and mice have 1000-fold fewer; however, cancer risk across species does not increase with the number of somatic cells and the lifespan of the organism. This observation is known as Peto's paradox. How much would evolution have to change the parameters of somatic evolution in order to equalize the cancer risk between species that differ by orders of magnitude in size? Analysis of previously published models of colorectal cancer suggests that a two- to three-fold decrease in the mutation rate or stem cell division rate is enough to reduce a whale's cancer risk to that of a human. Similarly, the addition of one to two required tumour-suppressor gene mutations would also be sufficient. We surveyed mammalian genomes and did not find a positive correlation of tumour-suppressor genes with increasing body mass and longevity. However, we found evidence of the amplification of TP53 in elephants, MAL in horses and FBXO31 in microbats, which might explain Peto's paradox in those species. Exploring parameters that evolution may have fine-tuned in large, long-lived organisms will help guide future experiments to reveal the underlying biology responsible for Peto's paradox and guide cancer prevention in humans.