Recent Publications by CFE Educators

As a result of ongoing regional disparities, the United Network for Organ Sharing (UNOS) implemented policy in May 2019 limiting exception points for waitlisted patients with hepatocellular carcinoma (HCC) to median Model for End-Stage Liver Disease at transplant in the area surrounding a transplant center minus 3 points (MMAT-3). The impact of this policy change remains unknown. We included adult patients with HCC (n = 4567) and without HCC (n = 19,773) in the UNOS database added to the waiting list before this policy change (May 7, 2017-May 18, 2019) and after (May 19, 2019-March 7, 2020). Cumulative incidence analysis estimated the probability of dropout within 1 year of listing decreased from 12.9% before the policy to 11.1% after the policy in candidates without HCC and from 14% to 10.7% in candidates with HCC. Incidence rates of liver transplantation (LT) and waitlist dropout varied significantly before the policy in patients with HCC and without HCC but nearly equalized in the postpolicy era. These effects were observed in both shorter and longer wait regions. With policy change being modeled as a time-dependent covariate, competing risk regression analyses estimated a decreased risk of dropout after policy change in the non-HCC group (cause-specific hazard ratio, 0.91; P = 0.02) after adjusting for demographic variables. These results suggest that the MMAT-3 policy has successfully reduced disparities in access to LT including across UNOS wait regions, although certain patients with HCC are now disadvantaged.

The σ receptor has attracted intense interest in cancer imaging, psychiatric disease, neuropathic pain and other areas of biology. Here we determined the crystal structure of this receptor in complex with the clinical candidate roluperidone and the tool compound PB28. These structures templated a large-scale docking screen of 490 million virtual molecules, of which 484 compounds were synthesized and tested. We identified 127 new chemotypes with affinities superior to 1 μM, 31 of which had affinities superior to 50 nM. The hit rate fell smoothly and monotonically with docking score. We optimized three hits for potency and selectivity, and achieved affinities that ranged from 3 to 48 nM, with up to 250-fold selectivity versus the σ receptor. Crystal structures of two ligands bound to the σ receptor confirmed the docked poses. To investigate the contribution of the σ receptor in pain, two potent σ-selective ligands and one potent σ/σ non-selective ligand were tested for efficacy in a mouse model of neuropathic pain. All three ligands showed time-dependent decreases in mechanical hypersensitivity in the spared nerve injury model, suggesting that the σ receptor has a role in nociception. This study illustrates the opportunities for rapid discovery of in vivo probes through structure-based screens of ultra large libraries, enabling study of underexplored areas of biology.