Frequent aneuploidy in primary human T cells after CRISPR-Cas9 cleavage

Multiple clinical trials of allogeneic T cell therapy use site-specific nucleases to disrupt T cell receptor (TCR) and other genes^1-6. In this study, using single-cell RNA sequencing, we investigated genome editing outcomes in primary human T cells transfected with CRISPR-Cas9 and guide RNAs targeting genes for TCR chains and programmed cell death protein 1. Four days after transfection, we found a loss of chromosome 14, harboring the TCRα locus, in up to 9% of the cells and a chromosome 14 gain in up to 1.4% of the cells. Chromosome 7, harboring the TCRβ locus, was truncated in 9.9% of the cells. Aberrations were validated using fluorescence in situ hybridization and digital droplet PCR. Aneuploidy was associated with reduced proliferation, induced p53 activation and cell death. However, at 11 days after transfection, 0.9% of T cells still had a chromosome 14 loss. Aneuploidy and chromosomal truncations are, thus, frequent outcomes of CRISPR-Cas9 cleavage that should be monitored and minimized in clinical protocols.

P12.15.B Astrocyte immunometabolic regulation of the glioblastoma microenvironment drives tumor pathogenicity

Background

Malignant brain tumors are the cause of a disproportionate level of morbidity and mortality among cancer patients, an unfortunate statistic that has remained constant for decades. Despite considerable advances in the molecular characterization of these tumors, targeting the cancer cells has yet to produce significant advances in treatment. An alternative strategy is to target cells in the glioblastoma microenvironment, such as tumor associated astrocytes. Astrocytes control multiple processes in health and disease, ranging from maintaining the brain's metabolic homeostasis, to modulating neuroinflammation. However, their role in glioblastoma pathogenicity is not well understood.

Material and Methods

Immunocompetent mice were implanted with murine glioma cell lines and the role of astrocyte in the tumor pathogenicity was analyzed, and further investigated using in-vitro co-cultures.

Results

Here we report that depletion of reactive astrocytes regresses glioblastoma and prolongs mouse survival. Analysis of the tumor-associated astrocyte translatome, revealed that astrocytes initiate transcriptional programs that shape the immune and metabolic compartments in the glioma microenvironment. Specifically, their expression of CCL2 and CSF1 governs the recruitment of tumor-associated macrophages and promotes a pro-tumorigenic macrophage phenotype. Concomitantly, we demonstrate that astrocyte-derived cholesterol is key to glioma cell survival, and that targeting astrocytic cholesterol efflux, via ABCA1, halts tumor progression. In summary, astrocytes control glioblastoma pathogenicity by reprogramming the immunological properties of the tumor microenvironment and supporting the non-oncogenic metabolic dependency of glioblastoma on cholesterol.

Conclusion

These findings suggest that targeting astrocyte immunometabolic signaling may help treat this uniformly lethal brain tumor.

Oxaliplatin/capecitabine vs oxaliplatin/infusional 5-FU in advanced colorectal cancer: the MRC COIN trial

Background:

COIN compared first-line continuous chemotherapy with the same chemotherapy given intermittently or with cetuximab in advanced colorectal cancer (aCRC).

Methods:

Choice between oxaliplatin/capecitabine (OxCap) and oxaliplatin/leucovorin (LV)/infusional 5-FU (OxFU) was by physician and patient choice and switching regimen was allowed. We compared OxCap with OxFU and OxCap+cetuximab with OxFU+cetuximab retrospectively in patients and examined efficacy, toxicity profiles and the effect of mild renal impairment.

Results:

In total, 64% of 2397 patients received OxCap(±cetuximab). Overall survival, progression free survival and overall response rate were similar between OxCap and OxFU but rate of radical surgeries was higher for OxFU. Progression free survival was longer for OxFU+cetuximab compared with OxCap+cetuximab but other efficacy measures were similar. Oxaliplatin/LV/infusional 5-FU (±cetuximab) was associated with more mucositis and infection whereas OxCap(±cetuximab) caused more gastrointestinal toxicities and palmar-plantar erythema. In total, 118 patients switched regimen, mainly due to toxicity; only 16% came off their second regimen due to intolerance. Patients with creatinine clearance (CrCl) 50–80 ml min⁻¹ on OxCap(±cetuximab) or OxFU+cetuximab had more dose modifications than those with better renal function.

Conclusions:

Overall, OxFU and OxCap are equally effective in treating aCRC. However, the toxicity profiles differ and switching from one regimen to the other for poor tolerance is a reasonable option. Patients with CrCl 50–80 ml min⁻¹ on both regimens require close toxicity monitoring.

Toxicity associated with combination oxaliplatin plus fluoropyrimidine with or without cetuximab in the MRC COIN trial experience

We present the preliminary toxicity data from the MRC COIN trial, a phase III randomised controlled trial of first-line therapy in advanced colorectal cancer, with particular reference to the addition of cetuximab to an oxaliplatin-fluoropyrimidine combination. A total of 804 patients were randomised between March 2005 and July 2006 from 78 centres throughout the United Kingdom. Patients were allocated to oxaliplatin plus fluoropyrimidine chemotherapy with or without the addition of weekly cetuximab. The choice of fluoropyrimidine (either 5-fluorouracil (5FU) or capecitabine) was decided by the treating physician and patient before randomisation. Toxicity data were collected from all patients. Two hundred and three patients received 5FU plus oxaliplatin (OxMdG, 25%), 333 oxaliplatin+capecitabine (Xelox, 41%), 102 received OxMdG+cetuximab (OxMdG+C, 13%) and 166 Xelox+cetuximab (21%). Percent grade 3/4 toxicities included diarrhoea 6, 15, 13 and 25%, nausea/vomiting 3, 7, 7 and 14% for OxMdG, Xelox, OxMdG+C and Xelox+C, respectively. Sixty-day all-cause mortality was 6, 5, 5 and 7%. Statistically significant differences were evident for patients receiving Xelox+cetuximab vs Xelox alone: diarrhoea relative risk (RR) 1.69 (1.17, 2.43, P=0.005) and nausea/vomiting RR 2.01 (1.16, 3.47, P=0.012). The excess toxicity observed in the oxaliplatin-, capecitabine-, cetuximab-treated patients led the trial management group to conclude that a capecitabine dose adjustment was required to maintain safety levels when using this regimen.

Peri-operative aspirin can prevent post-operative ischemia and thrombosis

Of the 30 million patients in the USA who undergo non-cardiac surgery every year, approximately 1.5 million suffer post-operative cardiovascular events. Surgical trauma and associated catecholamine release leads to platelet activation in the immediate post-operative period, as evidenced by a rise in circulating platelet release products. Platelet activation promotes platelet aggregation and hypercoagulability. Aspirin is widely used for its platelet inhibiting effects to prevent myocardial infarction and stroke. However, aspirin is not routinely started in the immediate peri-operative period, and even in high-risk patients already taking aspirin, aspirin is generally discontinued before elective surgery to improve intra-operative hemostasis. The risk-to-benefit ratios of administering vs withholding aspirin in the immediate peri-operative period have never been assessed and compared. We hypothesize that aspirin given pre-, intra- or immediately post-operatively will reduce post-operative ischemia and thrombotic events, including myocardial infarction and stroke, and that risk-benefit analysis would favor the administration of aspirin. This hypothesis can and should be tested in a prospective, randomized trial.

Transglutaminase induction by various cell death and apoptosis pathways

Clarification of the molecular details of forms of natural cell death, including apoptosis, has become one of the most challenging issues of contemporary biomedical sciences. One of the effector elements of various cell death pathways is the covalent cross-linking of cellular proteins by transglutaminases. This review will discuss the accumulating data related to the induction and regulation of these enzymes, particularly of tissue type transglutaminase, in the molecular program of cell death. A wide range of signalling pathways can lead to the parallel induction of apoptosis and transglutaminase, providing a handle for better understanding the exact molecular interactions responsible for the mechanism of regulated cell death.

Sclerosing peritonitis occurring in a hemodialysis patient

The pathogenesis of sclerosing peritonitis is poorly understood. In patients with end-stage renal failure, it has been described in association with continuous ambulatory peritoneal dialysis (CAPD), although it has not been described in patients treated exclusively by hemodialysis. We present a case of sclerosing peritonitis occurring in a 47-year-old man who was treated solely by hemodialysis. Additionally, the patient was diagnosed as having "nephrogenic ascites" 5 years before developing sclerosing peritonitis, and we discuss a possible link between these two conditions.