Multiplex analysis of intratumoural immune infiltrate and prognosis in patients with stage II–III colorectal cancer from the SCOT and QUASAR 2 trials: A retrospective analysis

Background Tumour-infiltrating CD8+ cytotoxic T cells confer favourable prognosis in colorectal cancer. The added prognostic value of other infiltrating immune cells is unclear and so we sought to investigate their prognostic value in two large clinical trial cohorts. Methods We used multiplex immunofluorescent staining of tissue microarrays to assess the densities of CD8+, CD20+, FoxP3+, and CD68+ cells in the intraepithelial and intrastromal compartments from tumour samples of patients with stage II–III colorectal cancer from the SCOT trial (ISRCTN59757862), which examined 3 months versus 6 months of adjuvant oxaliplatin-based chemotherapy, and from the QUASAR 2 trial (ISRCTN45133151), which compared adjuvant capecitabine with or without bevacizumab. Both trials included patients aged 18 years or older with an Eastern Cooperative Oncology Group performance status of 0–1. Immune marker predictors were analysed by multiple regression, and the prognostic and predictive values of markers for colorectal cancer recurrence-free interval by Cox regression were assessed using the SCOT cohort for discovery and QUASAR 2 cohort for validation. Findings After exclusion of cases without tissue microarrays and with technical failures, and following quality control, we included 2340 cases from the SCOT trial and 1069 from the QUASAR 2 trial in our analysis. Univariable analysis of associations with recurrence-free interval in cases from the SCOT trial showed a strong prognostic value of intraepithelial CD8 (CD8IE) as a continuous variable (hazard ratio [HR] for 75th vs 25th percentile [75vs25] 0·73 [95% CI 0·68–0·79], p=2·5 × 10−16), and of intrastromal FoxP3 (FoxP3IS; 0·71 [0·64–0·78], p=1·5 × 10−13) but not as strongly in the epithelium (FoxP3IE; 0·89 [0·84–0·96], p=1·5 × 10−4). Associations of other markers with recurrence-free interval were moderate. CD8IE and FoxP3IS retained independent prognostic value in bivariable and multivariable analysis, and, compared with either marker alone, a composite marker including both markers (CD8IE-FoxP3IS) was superior when assessed as a continuous variable (adjusted [a]HR75 vs 25 0·70 [95% CI 0·63–0·78], p=5·1 × 10−11) and when categorised into low, intermediate, and high density groups using previously published cutpoints (aHR for intermediate vs high 1·68 [95% CI 1·29–2·20], p=1·3 × 10−4; low vs high 2·58 [1·91–3·49], p=7·9 × 10−10), with performance similar to the gold-standard Immunoscore. The prognostic value of CD8IE-FoxP3IS was confirmed in cases from the QUASAR 2 trial, both as a continuous variable (aHR75 vs 25 0·84 [95% CI 0·73–0·96], p=0·012) and as a categorical variable for low versus high density (aHR 1·80 [95% CI 1·17–2·75], p=0·0071) but not for intermediate versus high (1·30 [0·89–1·88], p=0·17). Interpretation Combined evaluation of CD8IE and FoxP3IS could help to refine risk stratification in colorectal cancer. Investigation of FoxP3IS cells as an immunotherapy target in colorectal cancer might be merited

Rare diagnosis of intraosseous lipoma in the scapula of a 15-year-old domestic shorthair cat

Case summary A 15-year-old male castrated domestic shorthair cat originally presented to its primary care veterinarian with a chief complaint of a multi-month history of decreased appetite, weight loss and mild weight-bearing lameness. On physical examination, over the right scapula there was mild-to-moderate muscle wasting and a palpable firm, bony mass measuring approximately 3.5 cm × 3 cm. A complete blood count, chemistry panel, urinalysis, urine culture and baseline thyroxine were clinically unremarkable. Further diagnostics included CT, which revealed a large, expansile, irregularly mineralized mass centered over the caudoventral scapula at the site of attachment of the infraspinatus muscle. Following wide surgical excision by means of complete scapulectomy the patient regained function of the limb and has been free of disease since. The clinical institution’s pathology service examined the resected scapula with associated mass and diagnosed an intraosseous lipoma. Relevance and novel information Intraosseous lipoma is a rare form of bone neoplasia that has only been reported once in the small animal veterinary literature. Histopathology, clinical signs and radiographic changes were consistent with what is described in human literature. It is hypothesized that these tumors occur because of invasively growing adipose tissue within the medullary canal following trauma. Considering the rarity of primary bone tumors in cats, intraosseous lipomas should be considered as a differential diagnosis in future cases with similar signs and history

The Raccoon Polyomavirus Genome and Tumor Antigen Transcription Are Stable and Abundant in Neuroglial Tumors

UnlabelledRaccoon polyomavirus (RacPyV) is associated with 100% of neuroglial tumors in free-ranging raccoons. Other tumor-associated polyomaviruses (PyVs), including simian virus 40 (SV40), murine PyV, and Merkel cell PyV, are found integrated in the host genome in neoplastic cells, where they constitutively express splice variants of the tumor antigen (TAg) gene. We have previously reported that RacPyV exists only as an episome (nonintegrated) in neuroglial tumors. Here, we have investigated TAg transcription in primary tumor tissue by transcriptome analysis, and we identified the alternatively spliced TAg transcripts for RacPyV. We also determined that TAg was highly transcribed relative to host cellular genes. We further colocalized TAg DNA and mRNA by in situ hybridization and found that the majority of tumor cells showed positive staining. Lastly, we examined the stability of the viral genome and TAg transcription by quantitative reverse transcriptase PCR in cultured tumor cells in vitro and in a mouse xenograft model. When tumor cells were cultured in vitro, TAg transcription increased nearly 2 log-fold over that of parental tumor tissue by passage 17. Both episomal viral genome and TAg transcription were faithfully maintained in culture and in tumors arising from xenotransplantation of cultured cells in mice. This study represents a minimal criterion for RacPyV's association with neuroglial tumors and a novel mechanism of stability for a polyomavirus in cancer.ImportanceThe natural cycle of polyomaviruses in mammals is to persist in the host without causing disease, but they can cause cancer in humans or in other animals. Because this is an unpredictable and rare event, the oncogenic potential of polyomavirus is primarily evaluated in laboratory animal models. Recently, raccoon polyomavirus (RacPyV) was identified in neuroglial tumors of free-ranging raccoons. Viral copy number was consistently high in these tumors but was low or undetectable in nontumor tissue or in unaffected raccoons. Unlike other oncogenic polyomaviruses, RacPyV was episomal, not integrated, in these tumors. To determine the stability of the viral genome and sustained transcription of the oncogenic tumor antigen genes, we cultured primary raccoon tumor cells and passaged them in mice, confirming the nonintegrated state of the virus and the maintenance of viral gene transcription throughout. RacPyV provides a naturally occurring and tractable model for a novel mechanism of polyomavirus-mediated oncogenesis

Identification of a Second Raccoon-Associated Polyomavirus

Raccoon polyomavirus 1 (RacPyV1) is the suspected cause of an outbreak of fatal brain tumors among raccoons (Procyon lotor) in the western United States. Spleen samples from Georgia raccoons were screened for polyomaviruses. Although RacPyV1 was not detected, a previously unknown polyomavirus, which we designate RacPyV2, was identified and sequenced

BRD4 is associated with raccoon polyomavirus genome and mediates viral gene transcription and maintenance of a stem cell state in neuroglial tumour cells.

Polyomavirus infection often results in persistence of the viral genome with little or no virion production. However, infection of certain cell types can result in high viral gene transcription and either cytolysis or neoplastic transformation. While infection by polyomavirus is common in humans and many animals, major questions regarding viral persistence of most polyomaviruses remain unanswered. Specifically, identification of target cells for viral infection and the mechanisms polyomaviruses employ to maintain viral genomes within cells are important not only in ascribing causality to polyomaviruses in disease, but in understanding specific mechanisms by which they cause disease. Here, we characterize the cell of origin in raccoon polyomavirus (RacPyV)-associated neuroglial brain tumours as a neural stem cell. Moreover, we identify an association between the viral genome and the host cell bromodomain protein, BRD4, which is involved in numerous cellular functions, including cell cycle progression, differentiation of stem cells, tethering of persistent DNA viruses, and regulation of viral and host-cell gene transcription. We demonstrate that inhibition of BRD4 by the small molecule inhibitors (+)-JQ1 and IBET-151 (GSK1210151A) results in reduced RacPyV genome within cells in vitro, as well as significant reduction of viral gene transcripts LT and VP1, highlighting its importance in both maintenance of the viral genome and in driving oncogenic transformation by RacPyV. This work implicates BRD4 as a central protein involved in RacPyV neuroglial tumour cell proliferation and in the maintenance of a stem cell state