Small molecule XIAP inhibitors enhance TRAIL-Lnduced apoptosis and antitumor activity in preclinical models of pancreatic carcinoma

Evasion of apoptosis is a characteristic feature of pancreatic cancer, a prototypic cancer that is refractory to current treatment approaches. Hence, there is an urgent need to design rational strategies that counter apoptosis resistance. To explore X-Iinked inhibitor of apoptosis (XIAP) as a therapeutic target in pancreatic cancer, we analyzed the expression of XIAP in pancreatic tumor samples and evaluated the effect of small molecule XIAP inhibitors alone and in combination with tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) against pancreatic carcinoma in vitro and in vivo. Here, we report that XIAP is highly expressed in pancreatic adenocarcinoma samples compared with normal pancreatic ducts. Small molecule XIAP inhibitors synergize with TRAIL to induce apoptosis and to inhibit long-term clonogenic survival of pancreatic carcinoma cells. In contrast, they do not reverse the lack of toxicity of TRAIL on nonmalignant cells in vitro or normal tissues in vivo, pointing to a therapeutic index. Most importantly, XIAP inhibitors cooperate with TRAIL to trigger apoptosis and suppress pancreatic carcinoma growth in vivo in two preclinical models, i.e., the chorioallantoic membrane model and a mouse xenograft model. Parallel immunohistochemical analysis of tumor tissue under therapy reveals that the XIAP inhibitor acts in concert with TRAIL to cause caspase-3 activation and apoptosis. In conclusion, our findings provide, for the first time, evidence in vivo that XIAP inhibitors prime pancreatic carcinoma cells for TRAIL-induced apoptosis and potentiate the antitumor activity of TRAIL against established pancreatic carcinoma. These findings build the rationale for further (pre)clinical development of XIAP inhibitors and TRAIL against pancreatic cancer. © 2009 American Association for Cancer Research

Identification of unique neoantigen qualities in long-term survivors of pancreatic cancer

Pancreatic ductal adenocarcinoma is a lethal cancer with fewer than 7% of patients surviving past 5 years. T-cell immunity has been linked to the exceptional outcome of the few long-term survivors1,2, yet the relevant antigens remain unknown. Here we use genetic, immunohistochemical and transcriptional immunoprofiling, computational biophysics, and functional assays to identify T-cell antigens in long-term survivors of pancreatic cancer. Using whole-exome sequencing and in silico neoantigen prediction, we found that tumours with both the highest neoantigen number and the most abundant CD8+ T-cell infiltrates, but neither alone, stratified patients with the longest survival. Investigating the specific neoantigen qualities promoting T-cell activation in long-term survivors, we discovered that these individuals were enriched in neoantigen qualities defined by a fitness model, and neoantigens in the tumour antigen MUC16 (also known as CA125). A neoantigen quality fitness model conferring greater immunogenicity to neoantigens with differential presentation and homology to infectious disease-derived peptides identified long-term survivors in two independent datasets, whereas a neoantigen quantity model ascribing greater immunogenicity to increasing neoantigen number alone did not. We detected intratumoural and lasting circulating T-cell reactivity to both high-quality and MUC16 neoantigens in long-term survivors of pancreatic cancer, including clones with specificity to both high-quality neoantigens and predicted cross-reactive microbial epitopes, consistent with neoantigen molecular mimicry. Notably, we observed selective loss of high-quality and MUC16 neoantigenic clones on metastatic progression, suggesting neoantigen immunoediting. Our results identify neoantigens with unique qualities as T-cell targets in pancreatic ductal adenocarcinoma. More broadly, we identify neoantigen quality as a biomarker for immunogenic tumours that may guide the application of immunotherapies

Genomic correlates of extreme pathologic response following neoadjuvant chemotherapy in locally advanced gastric cancer to reveal distinct vulnerabilities

441 Background: Clinical factors associated with pathologic response (PResp) following neoadjuvant chemotherapy (NCT) in locally advanced gastric cancer (LAGC) are well studied; however, genomic correlates of such response have not been previously investigated. Methods: Evaluable pre-NCT tumor samples from patients with LAGC who underwent resection and demonstrated extreme pathologic response (EPR; ≤10% PResp: n = 21, ≥80% PResp: n = 19) were sequenced using a targeted exome capture platform. Gene- and signaling pathway-level correlates of EPR and disease-specific survival (DSS) were examined. Results: Of 40 patients, a majority had ≥cT2/N+ disease and were treated with predominantly platinum (98%) or 5-FU (88%) based NCT regimens. Two patients with MSI-high tumors had ≤10% PResp and were excluded from analysis. The EPR cohorts did not differ significantly in demographic or clinical (i.e., tumor location, cT/N status, NCT regimen, extent of gastrectomy, number of lymph nodes examined, or margin status) characteristics. Although EPR cohorts did not differ with respect to tumor differentiation/grade, Lauren classification, proportions of TCGA consensus CIN or GS subtypes, tumors with ≤10% PResp were more likely to have vascular (P < 0.001) and perineural (P = 0.007) invasion. At median follow-up of 31m (IQR 21-57), ≥80% PResp was associated with improved DSS compared with ≤10% PResp (median NR vs. 32m, P = 0.04). On gene-level analysis, tumors with ≤10% PResp were significantly more likely to be ERBB2-altered (32% vs 5%, P = 0.04) compared with ≥80% PResp tumors. Conversely, ARID1A truncating mutations were enriched in tumors with ≥80% vs ≤10% PResp (32% vs 5%, P = 0.04). There was no difference in pathway-level alteration frequency between EPR cohorts. While frequency of oncogenic TP53 alterations was similar between EPR cohorts, TP53-altered tumors were associated with worse DSS vs TP53-wildtype tumors (median 80m vs 24m, P = 0.005) in patients demonstrating ≤10%, but not ≥80%, PResp. Conclusions: Genomic comparison of cohorts demonstrating EPR after NCT in LAGC reveal molecular vulnerabilities with distinct prognostic and therapeutic implications

Age-Dependent Sex Bias in Clinical Malarial Disease in Hypoendemic Regions

<div><h3>Background and Objectives</h3><p>Experimental models show a male bias in murine malaria; however, extant literature on biases in human clinical malaria is inconclusive. Studies in hyperendemic areas document an absence of sexual dimorphism in clinical malaria. Data on sex bias in clinical malaria in hypoendemic areas is ambiguous—some reports note a male bias but do not investigate the role of differential mosquito exposure in that bias. Moreover, these studies do not examine whether the bias is age related. This study investigates whether clinical malaria in hypoendemic regions exhibits a sex bias and whether this bias is age-dependent. We also consider the role of vector exposure in this bias.</p> <h3>Methods</h3><p>Retrospective passive clinical malaria datasets (2002–2007) and active surveillance datasets (2000–2009) were captured for the hypoendemic Mumbai region in Western India. To validate findings, passive retrospective data was captured from a primary malaria clinic (2006–2007) in hypoendemic Rourkela (Eastern India). Data was normalized by determining percent slide-positivity rates (SPRs) for males and females, and parasite-positivity distributions were established across age groups. The Mann–Whitney test, Wilcoxon Signed Rank test, and Chi-square analysis were used to determine statistical significances.</p> <h3>Results</h3><p>In both the Mumbai and Rourkela regions, clinical malaria exhibited an adult male bias (p<0.01). A sex bias was not observed in children aged ≤10. Post-puberty, male SPRs were significantly greater than females SPRs (p<0.01). This adult male bias was observed for both vivax and falciparum clinical disease. Analysis of active surveillance data did not reveal an age or sex bias in the frequency of parasite positivity.</p> <h3>Conclusion</h3><p>This study demonstrates an age-dependent sex bias in clinical malaria in hypoendemic regions and enhanced incidence of clinical malaria in males following puberty. Possible roles of sex hormones, vector exposure, co-infections, and other factors in this enhanced susceptibility are discussed.</p> </div

Age distributions of SPRs of males and females in the clinical malaria datasets.

<p>A, B, Box plots showing the 25th and 75th percentiles, together with the median, with whiskers showing the minimum and maximum percent slide-positivity rates for males and females across age groups in the Mumbai region for clinical vivax (A) and falciparum (B) malaria. C,D, Box plots as above showing the minimum and maximum percent slide-positivity rates for males and females across age groups in Rourkela for clinical vivax (C) and falciparum (D) malaria. Statistically significant values obtained by the Mann–Whitney test are indicated.</p

Age distributions of differences between male and female SPRs in the clinical malaria and active surveillance datasets in the Mumbai region.

<p>A,C, Box plot showing the 25th and 75th percentiles, together with the median, with whiskers showing the minimum and maximum difference in the percent slide-positivity rates between males and females across age groups in the clinical malaria dataset for vivax (A) and falciparum (C) malaria. B,D, Box plots as in A showing the difference in the percent slide-positivity rates between males and females across age groups who tested positive for <i>P. vivax</i> (B) and <i>P. falciparum</i> (D) in the active surveillance programme. Data were compared with the difference of male/female SPRs expected under the hypothesis of neutrality (0, red line) and were analyzed with the Mann–Whitney test. Statistically significant values are shown in black. Numbers in red indicate statistically significant p values obtained by Wilcoxon Signed Rank test under the hypothesis that the median of the group did not differ significantly from zero. The test could not be applied to the falciparum data in the active surveillance dataset.</p