ABTL0812 is a first-in-class small molecule with anti-cancer activity, which is currently in clinical evaluation in a phase 2 trial in patients with advanced endometrial and squamous non-small cell lung carcinoma (NCT03366480). Previously, we showed that ABTL0812 induces TRIB3 pseudokinase expression, resulting in the inhibition of the AKT-MTORC1 axis and macroautophagy/autophagy-mediated cancer cell death. However, the precise molecular determinants involved in the cytotoxic autophagy caused by ABTL0812 remained unclear. Using a wide range of biochemical and lipidomic analyses, we demonstrated that ABTL0812 increases cellular long-chain dihydroceramides by impairing DEGS1 (delta 4-desaturase, sphingolipid 1) activity, which resulted in sustained ER stress and activated unfolded protein response (UPR) via ATF4-DDIT3-TRIB3 that ultimately promotes cytotoxic autophagy in cancer cells. Accordingly, pharmacological manipulation to increase cellular dihydroceramides or incubation with exogenous dihydroceramides resulted in ER stress, UPR and autophagy-mediated cancer cell death. Importantly, we have optimized a method to quantify mRNAs in blood samples from patients enrolled in the ongoing clinical trial, who showed significant increased DDIT3 and TRIB3 mRNAs. This is the first time that UPR markers are reported to change in human blood in response to any drug treatment, supporting their use as pharmacodynamic biomarkers for compounds that activate ER stress in humans. Finally, we found that MTORC1 inhibition and dihydroceramide accumulation synergized to induce autophagy and cytotoxicity, phenocopying the effect of ABTL0812. Given the fact that ABTL0812 is under clinical development, our findings support the hypothesis that manipulation of dihydroceramide levels might represents a new therapeutic strategy to target cancer. Abbreviations: 4-PBA: 4-phenylbutyrate; AKT: AKT serine/threonine kinase; ATG: autophagy related; ATF4: activating transcription factor 4; Cer: ceramide; DDIT3: DNA damage inducible transcript 3; DEGS1: delta 4-desaturase, sphingolipid 1; dhCer: dihydroceramide; EIF2A: eukaryotic translation initiation factor 2 alpha; EIF2AK3: eukaryotic translation initiation factor 2 alpha kinase 3; ER: endoplasmic reticulum; HSPA5: heat shock protein family A (Hsp70) member 5; MAP1LC3B: microtubule associated protein 1 light chain 3 beta; MEF: mouse embryonic fibroblast; MTORC1: mechanistic target of rapamycin kinase complex 1; NSCLC: non-small cell lung cancer; THC: Δ⁹-tetrahydrocannabinol; TRIB3: tribbles pseudokinase 3; XBP1: X-box binding protein 1; UPR: unfolded protein response.

The early prediction of the severity of acute pancreatitis still represents a challenge for clinicians. Experimental studies have revealed the generation of specific halogenated lipids, in particular oleic acid chlorohydrin, in the early stages of acute pancreatitis. We hypothesized that the levels of circulating oleic acid chlorohydrin might be a useful early prognostic biomarker in acute pancreatitis in humans. In a prospective, multicenter cohort study, plasma samples collected within 24 h after presentation in the emergency room from 59 patients with acute pancreatitis and from 9 healthy subjects were assessed for oleic acid chlorohydrin levels. Pancreatitis was mild in 30 patients, moderately severe in 16 and severe in 13. Oleic acid chlorohydrin levels within 24 h after presentation were significantly higher in patients that later progressed to moderate and severe acute pancreatitis. Using 7.49 nM as the cutoff point, oleic acid chlorohydrin distinguished mild from moderately severe-to-severe pancreatitis with high sensitivity/specificity (96.6/90.0%) and positive/negative predictive values (90.3/96.4%). Using 32.40 nM as the cutoff value sensitivity, specificity, positive and negative predictive values were all 100% for severe acute pancreatitis. It was found to be a better prognostic marker than BISAP score, hematocrit at 48 h, SIRS at admission, persistent SIRS or C-reactive protein at 48 h. Oleic acid chlorohydrin concentration in plasma is elevated in patients with acute pancreatitis on admission and correlates with a high degree with the final severity of the disease, indicating that it has potential to serve as an early prognostic marker for acute pancreatitis severity.

Gene therapy for Niemann-Pick type A disease is safe in nonhuman primates and has therapeutic effects in a mouse model.

CCR5 is not only a coreceptor for HIV‐1 infection in CD4 ⁺ T cells, but also contributes to their functional fitness. Here, we show that by limiting transcription of specific ceramide synthases, CCR5 signaling reduces ceramide levels and thereby increases T‐cell antigen receptor (TCR) nanoclustering in antigen‐experienced mouse and human CD4 ⁺ T cells. This activity is CCR5‐specific and independent of CCR5 co‐stimulatory activity. CCR5‐deficient mice showed reduced production of high‐affinity class‐switched antibodies, but only after antigen rechallenge, which implies an impaired memory CD4 ⁺ T‐cell response. This study identifies a CCR5 function in the generation of CD4 ⁺ T‐cell memory responses and establishes an antigen‐independent mechanism that regulates TCR nanoclustering by altering specific lipid species.