Citations

Abstract Nicotinamide adenine dinucleotide (NAD) levels decline during aging, contributing to physical and metabolic dysfunction. The NADase CD38 plays a key role in age‐related NAD decline. Whether the inhibition of CD38 increases lifespan is not known. Here, we show that the CD38 inhibitor 78c increases lifespan and healthspan of naturally aged mice. In addition to a 10% increase in median survival, 78c improved exercise performance, endurance, and metabolic function in mice. The effects of 78c were different between sexes. Our study is the first to investigate the effect of CD38 inhibition in naturally aged animals.

Nicotinamide adenine dinucleotide (NAD) acts as a cofactor in several oxidation-reduction (redox) reactions and is a substrate for a number of nonredox enzymes. NAD is fundamental to a variety of cellular processes including energy metabolism, cell signaling, and epigenetics. NAD homeostasis appears to be of paramount importance to health span and longevity, and its dysregulation is associated with multiple diseases. NAD metabolism is dynamic and maintained by synthesis and degradation. The enzyme CD38, one of the main NAD-consuming enzymes, is a key component of NAD homeostasis. The majority of CD38 is localized in the plasma membrane with its catalytic domain facing the extracellular environment, likely for the purpose of controlling systemic levels of NAD. Several cell types express CD38, but its expression predominates on endothelial cells and immune cells capable of infiltrating organs and tissues. Here we review potential roles of CD38 in health and disease and postulate ways in which CD38 dysregulation causes changes in NAD homeostasis and contributes to the pathophysiology of multiple conditions. Indeed, in animal models the development of infectious diseases, autoimmune disorders, fibrosis, metabolic diseases, and age-associated diseases including cancer, heart disease, and neurodegeneration are associated with altered CD38 enzymatic activity. Many of these conditions are modified in CD38-deficient mice or by blocking CD38 NADase activity. In diseases in which CD38 appears to play a role, CD38-dependent NAD decline is often a common denominator of pathophysiology. Thus, understanding dysregulation of NAD homeostasis by CD38 may open new avenues for the treatment of human diseases.

Metastatic neuroendocrine tumour (NET) to brain has been reported in 1.5–5% of patients with NETs. Differentiation between intracranial NET metastasis and meningiomas can cause a diagnostic dilemma. We present a symptomatic case of a 66-year-old male with a history of left-sided skull base mass. The diagnosis of a meningioma was made based on the MRI findings and clinical presentation. The patient received radiation and the mass remained stable on serial MRI images at follow-up visits. Five years after his initial presentation, the patient’s mass showed further growth. He also complained of worsening of his recent diagnosis of irritable bowel syndrome and fluctuations in his blood pressure. Surgical resection was performed, and histopathological features were consistent with moderately differentiated neuroendocrine tumour. Further evaluation with 68 Gallium-DOTATATE positron emission-computed tomography (Ga-68 PET/CT) showed metastatic disease involving the bones, lymph nodes, and liver without convincing evidence of the location of primary malignancy within the bowel loops or the pancreas. The patient was started on combination of capecitabine and temozolomide with partial response and significant improvement of his symptoms. This case highlights the clinical and radiological behaviour of intracranial NET that can mimic the diagnosis of meningioma.

101 Background: Colorectal cancer (CRC) incidence and mortality have decreased since the 1970s, but the incidence in young adults (20-49 years, named early-onset CRC, eoCRC) has been increasing. eoCRC patients with metastatic disease are treated with the same standard regimens as late-onset CRC (loCRC, age ≥ 50 years) although detailed response data for eoCRC are largely missing. Methods: Individual patient data on 7,604 subjects with metastatic eoCRC from 11 first line randomized bevacizumab studies between 2000 and 2012 in the ARCAD advanced colorectal cancer database were pooled. The distributions of demographics, clinicopathological features, biomarkers, and outcome data were summarized by age groups. Progression-free survival (PFS) and overall survival (OS) were assessed by Kaplan-Meier curves and Cox models stratified by treatment arms within studies, adjusting for potential confounders. Predictive value of age group was evaluated by testing interaction effect between treatment and age variables. Results: Female eoCRC are more commonly seen compared to loCRC (46.8% vs. 38.7%, p<0.0001). Patients with eoCRC (n=1,289) were significantly more likely to have had prior metastasectomy (17.5% vs. 13.5%, p=0.043) and lung metastatic disease (67% vs. 59.8%, p<0.001), but less likely to have distant lymph node metastatic disease (58.8 vs. 62.9%, p=0.036) or KRAS mutation (29.2% vs. 34.4%, p=0.042) compared to those with loCRC (n=6,315). eoCRC and loCRC patients had similar distributions according to PS, primary tumor sidedness, prior primary tumor resection, liver involvement, peritoneal involvement, number of metastatic sites, NRAS and BRAF. Age of disease onset was not a statistically significant prognostic factor for PFS in univariate and multivariate analysis (seen in table). Bevacizumab in addition to chemo improved PFS in eoCRC population (9.9 vs. 6.8 months, HR = 0.66, p<0.001), which was similar to the findings in loCRC population (9.4 vs. 7.3 months, HR= 0.73, p<0.001, interaction p=0.54). By multivariate analysis, a greater improvement in PFS was noted for the addition of bevacizumab in eoCRC relative to LoCRC patients (HR = 0.62 vs. HR = 0.82). Conclusions: Treatment naive eoCRC patients with metastatic disease derive similar benefit from bevacizumab relative to their average age counterparts.[Table: see text]