Successful treatment of many patients with advanced cancer using antibodies against programmed cell death 1 (PD-1; also known as PDCD1) and its ligand (PD-L1; also known as CD274) has highlighted the critical importance of PD-1/PD-L1-mediated immune escape in cancer development. However, the genetic basis for the immune escape has not been fully elucidated, with the exception of elevated PD-L1 expression by gene amplification and utilization of an ectopic promoter by translocation, as reported in Hodgkin and other B-cell lymphomas, as well as stomach adenocarcinoma. Here we show a unique genetic mechanism of immune escape caused by structural variations (SVs) commonly disrupting the 3' region of the PD-L1 gene. Widely affecting multiple common human cancer types, including adult T-cell leukaemia/lymphoma (27%), diffuse large B-cell lymphoma (8%), and stomach adenocarcinoma (2%), these SVs invariably lead to a marked elevation of aberrant PD-L1 transcripts that are stabilized by truncation of the 3'-untranslated region (UTR). Disruption of the Pd-l1 3'-UTR in mice enables immune evasion of EG7-OVA tumour cells with elevated Pd-l1 expression in vivo, which is effectively inhibited by Pd-1/Pd-l1 blockade, supporting the role of relevant SVs in clonal selection through immune evasion. Our findings not only unmask a novel regulatory mechanism of PD-L1 expression, but also suggest that PD-L1 3'-UTR disruption could serve as a genetic marker to identify cancers that actively evade anti-tumour immunity through PD-L1 overexpression.

Although adoptive transfer of cytotoxic T lymphocytes (CTL) offer a promising cancer therapeutic direction, the generation of antigen-specific CTL from patients has faced difficulty in efficient expansion in ex vivo culture. To resolve this issue, several groups have proposed that induced pluripotent stem cell technology be applied for the expansion of antigen-specific CTL, which retain expression of the same T-cell receptor as original CTL. However, in these previous studies, the regenerated CTL are mostly of the CD8aa þ innate type and have less antigen-specific cytotoxic activity than primary CTL. Here we report that, by stimulating purified iPSC-derived CD4/CD8 double-positive cells with anti-CD3 antibody, T cells expressing CD8ab were generated and exhibited improved antigen-specific cytotoxicity compared with CD8aa þ CTL. Failure of CD8ab T-cell production using the previous method was found to be due to killing of doublepositive cells by the double-negative cells in the mixed cultures. We found that WT1 tumor antigen-specific CTL regenerated by this method prolonged the survival of mice bearing WT1-expressing leukemic cells. Implementation of our methods may offer a useful clinical tool. Cancer Res; 76(23); 6839-50. Ó2016 AACR.

Sense of agency refers to the feeling that one’s voluntary actions caused external events. Past studies have shown that compression of the subjective temporal interval between actions and external events, called intentional binding, is closely linked to the experience of agency. Current theories postulate that the experience of agency is constructed via predictive and postdictive pathways. One remaining problem is the source of human causality bias; people often make misjudgments on the causality of voluntary actions and external events depending on their rewarding or punishing outcomes. Although human causality bias implies that sense of agency can be modified by post-action information, convincing empirical findings for this issue are lacking. Here, we hypothesized that sense of agency would be modified by affective valences of action outcomes. To examine this issue, we investigated how rewarding and punishing outcomes following voluntary action modulate behavioral measures of agency using intentional binding paradigm and classical conditioning procedures. In the acquisition phase, auditory stimuli were paired with positive, neutral or negative monetary outcomes. Tone-reward associations were evaluated using reaction times and preference ratings. In the experimental session, participants performed a variant of intentional binding task, where participants made timing judgments for onsets of actions and sensory outcomes while playing simple slot games. Our results showed that temporal binding was modified by affective valences of action outcomes. Specifically, intentional binding was attenuated when negative outcome occurred, consistent with self-serving bias. Our study not only provides evidence for postdictive modification of agency, but also proposes a possible mechanism of human causality bias.

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SummaryHLA haplotype-homozygous (HLA-homo) induced pluripotent stem cells (iPSCs) are being prepared to be used for allogeneic transplantation of regenerated tissue into recipients carrying an identical haplotype in one of the alleles (HLA-hetero). However, it remains unaddressed whether natural killer (NK) cells respond to these regenerated cells. HLA-C allotypes, known to serve as major ligands for inhibitory receptors of NK cells, can be classified into group 1 (C1) and group 2 (C2), based on their binding specificities. We found that the T cells and vascular endothelial cells regenerated from HLA-homo-C1/C1 iPSCs were killed by specific NK cell subsets from a putative HLA-hetero-C1/C2 recipient. Such cytotoxicity was canceled when target cells were regenerated from iPSCs transduced with the C2 gene identical to the recipient. These results clarify that NK cells can kill regenerated cells by sensing the lack of HLA-C expression and further provide the basis for an approach to prevent such NK cell-mediated rejection responses.

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