SummaryImmune evasion is a hallmark of cancer. Losing the ability to present neoantigens through human leukocyte antigen (HLA) loss may facilitate immune evasion. However, the polymorphic nature of the locus has precluded accurate HLA copy-number analysis. Here, we present loss of heterozygosity in human leukocyte antigen (LOHHLA), a computational tool to determine HLA allele-specific copy number from sequencing data. Using LOHHLA, we find that HLA LOH occurs in 40% of non-small-cell lung cancers (NSCLCs) and is associated with a high subclonal neoantigen burden, APOBEC-mediated mutagenesis, upregulation of cytolytic activity, and PD-L1 positivity. The focal nature of HLA LOH alterations, their subclonal frequencies, enrichment in metastatic sites, and occurrence as parallel events suggests that HLA LOH is an immune escape mechanism that is subject to strong microenvironmental selection pressures later in tumor evolution. Characterizing HLA LOH with LOHHLA refines neoantigen prediction and may have implications for our understanding of resistance mechanisms and immunotherapeutic approaches targeting neoantigens.Video Abstract

To investigate whether sclerosing cholangitis with an autoimmune serology characteristic of autoimmune hepatitis (AIH) and AIH are distinct entities, we studied 55 consecutive children with clinical and/or biochemical evidence of liver disease and circulating antinuclear (ANA), anti-smooth muscle (SMA), and/or liver-kidney-microsomal type 1 (LKM1) autoantibodies. They underwent liver biopsy, direct cholangiography, sigmoidoscopy, and rectal biopsy at presentation. Twenty-eight were diagnosed as AIH in the absence and 27 autoimmune sclerosing cholangitis (ASC) in the presence of radiological features of cholangiopathy. Twenty-six ASC and 20 AIH had ANA and/or SMA; 1 ASC and 8 AIH LKM1 autoantibody. Similarities between the 2 conditions included most clinical and biochemical parameters and a lower frequency of HLA DR4. Inflammatory bowel disease and histological biliary changes were more common in ASC; coagulopathy, hypoalbuminemia, lymphocytic periportal hepatitis, and HLA DR3 were more common in AIH. Histological biliary changes were observed in 65% of ASC and 31% of AIH patients. Eighty-nine percent responded to immunosuppression. Follow-up liver biopsies from 17 ASC and 18 AIH patients had similarly reduced inflammatory activity and no progression to cirrhosis. Sixteen follow-up cholangiograms from AIH patients and 9 from ASC patients were unchanged, while 8 ASC patients showed a progressive cholangiopathy. One child with AIH and ulcerative colitis developed sclerosing cholangitis 8 years after presentation. At 2 to 16 years (median, 7 years) from presentation, all patients are alive, including 4 ASC patients who underwent liver transplantation. In conclusion, ASC and AIH are similarly prevalent in childhood; cholangiography is often needed to distinguish between these 2 entities, which are likely to lie within the same disease process. (HEPATOLOGY 2001;33:544-553.)

SummaryCD25 is expressed at high levels on regulatory T (Treg) cells and was initially proposed as a target for cancer immunotherapy. However, anti-CD25 antibodies have displayed limited activity against established tumors. We demonstrated that CD25 expression is largely restricted to tumor-infiltrating Treg cells in mice and humans. While existing anti-CD25 antibodies were observed to deplete Treg cells in the periphery, upregulation of the inhibitory Fc gamma receptor (FcγR) IIb at the tumor site prevented intra-tumoral Treg cell depletion, which may underlie the lack of anti-tumor activity previously observed in pre-clinical models. Use of an anti-CD25 antibody with enhanced binding to activating FcγRs led to effective depletion of tumor-infiltrating Treg cells, increased effector to Treg cell ratios, and improved control of established tumors. Combination with anti-programmed cell death protein-1 antibodies promoted complete tumor rejection, demonstrating the relevance of CD25 as a therapeutic target and promising substrate for future combination approaches in immune-oncology.

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Brain concentrations of substances inhibiting the binding of [3H]flumazenil to its receptors are increased in some patients with hepatic encephalopathy due to fulminant hepatic failure. The origin of these substances is unknown, but these findings provide a rational basis for trials of benzodiazepine-receptor antagonists in the management of this disorder.