Recurrent somatic mutations in the key spliceosome component, SF3B1, have been identified at various frequencies across several cancer types. The most common hotspot mutation is the K700E missense mutation, and while its effects on splicing have been well characterised at the molecular level, the mis-spliced genes that contribute to cancer progression and/or dictate responses to therapy are still unclear. Here, we used we use cell line modelling to assess the impact of the SF3B1K700E mutation on the cellular response to various apoptosis-inducing agents. Our data suggest that the SF3B1K700E mutation leads to reduced cFLIP levels, along with defects in the splicing and translation of BCL2, causing a shift in the balance of pro- and anti-apoptotic genes and proteins, which confers greater sensitivity to the bivalent SMAC mimetic, BV-6. As such, BV-6 may represent a therapeutic opportunity for patients with SF3B1 mutant cancers.

Background: The Dual Erb B Inhibition in Oesophago-gastric Cancer (DEBIOC) trial reported an acceptable safety profile for neoadjuvant oxaliplatin and capecitabine (Xelox) +/- AZD8931 in oesophageal adenocarcinoma (OAC) but limited efficacy. We evaluated the impact of neoadjuvant Xelox +/- AZD8931, a novel small-molecule inhibitor with equipotent activity against epidermal growth factor receptor (EGFR), human epidermal growth factor receptor (HER)2 and HER3, on biological pathways using a unique software-driven solution. Patients and methods: Transcriptomic profiles from 25 pre-treatment formalin-fixed paraffin-embedded OAC biopsies and 18 matched resection specimens, treated with Xelox + AZD8931 (n = 16) and Xelox alone (n = 9), were analysed using the Almac claraT total mRNA report analysing 92 gene signatures, 100 unique single-gene drug targets and 7337 single genes across 10 hallmarks of cancer. Gene-set enrichment analysis (GSEA) was utilised to investigate pathways governing pathological response. Tumour-infiltrating lymphocytes (TILs) were assessed digitally using the QuPath software. Results: Hierarchical clustering identified three molecular subgroups classified by activation of innate immune signalling. The immune-high subgroup was associated with HER2 positivity, increased pathological response and a marked reduction in immune signalling and TILs following neoadjuvant therapy. The immune-low cluster was predominantly HER2/EGFR-negative, and EGFR positivity was associated with the immune-mixed subgroup. Treatment with neoadjuvant therapy induced common resistance mechanisms, such as angiogenesis and epithelial emesenchymal transition signalling, and a reduction in DNA repair signatures. Addition of AZD8931 was associated with reduction of expression of EGFR, HER2 and AKT pathways and also promoted an immunosuppressive microenvironment. GSEA showed that patients with a pathological response to treatment had increased immune signalling, whereas non-responders to neoadjuvant therapy were enriched for nucleotide repair and cellular growth through the action of E2F transcription factors. Conclusion: OAC may be subdivided into three immune-related subgroups which undergo modulation in response to neoadjuvant therapy with marked suppression of the immune microenvironment in HER2-positive/immune-high tumours.

PDF file - 235K, Clinical relevance of AXL in CRC tissues.

PDF file - 179K, Effect of AXL siRNA on migration, proliferation and survival of CRC cells.

PDF file - 223K, Univariate and multivariate analyses for OS, DSS, DFS and AXL-LOW and AXL-HIGH in stage II/III CRC group (publicly-available CRC microarray dataset).

PDF file - 213K, Migration, proliferation rates and RTK profiling of HCT116 parental and invasive cells.

PDF file - 133K, Clinicopathological features of the colorectal cancer patient cohort.

EphA2 and EFNA1 expression levels in colorectal cancer cells.

Role of p53, Src family kinases and RAS/MAPK pathway in regulating EphA2 expression levels.

In recent years there has been rising interest in the field of protein-protein conjugation, especially related to bispecific antibodies (bsAbs) and their therapeutic applications. These constructs contain two paratopes capable of binding two distinct epitopes on target molecules and are thus able to perform complex biological functions (mechanisms of action) not available to monospecific mAbs. Traditionally these bsAbs have been constructed through protein engineering, but recently chemical methods for their construction have started to (re)emerge. While these have been shown to offer increased modularity, speed, and for some methods even the inherent capacity for further functionalization (e.g., with small molecule cargo), most of these approaches lacked the ability to include a fragment crystallizable (Fc) modality. The Fc component of IgG antibodies offers effector function and increased half-life. Here we report a first-in-class disulfide rebridging and click-chemistry-based method for the generation of Fc-containing, IgG-like mono-and bispecific antibodies. These are in the FcZ-(FabX)-FabY format, i.e., two distinct Fabs and an Fc, potentially all from different antibodies, attached in a homogeneous and covalent manner. We have dubbed these molecules synthetic antibodies (SynAbs). We have constructed a T cell engager (TCE) SynAb, FcCD20-(FabHER2)-FabCD3, and have confirmed that it exhibits the expected biological functions, including the ability to kill HER2+ target cells in a coculture assay with T cells.

The role of microenvironment-derived ligands in regulating EphA2 expression levels.

PDF file - 165K, Univariate and multivariate analyses in stage II-III CRC group (Singapore dataset) using Cox proportional hazards regression.

PDF file - 223K, Effect of 5-FU treatment on migration and proliferation of CRC cell lines.

PDF file - 53K, Statistical analysis.

PDF file - 190K, Effect of AXL small molecule inhibition on downstream signalling pathways and migration in CRC cell lines.

Supplementary table 1. Clinical-pathological features of the resection-only and chemotherapy/resection stage II/III colorectal cancer patient cohorts with mature survival data in the Singapore dataset. Supplementary table 2. EphA2 and clinical-pathological correlates in CRC. Correlation between EphA2 and CD44, LGR5, CD133, Ki-67 and AXL in 509 stage I-IV CRC cases of the Singapore dataset. Supplementary table 3. Statistical associations between pairs of factors in the surgery only (A) and surgery/chemotherapy (B) stage II/III groups in the Singapore dataset. Supplementary table 4. A. Univariate and multivariate analysis (Cox proportional hazards regression) of resection-chemotherapy stage II/III patient group. B. Final multivariate model (Cox proportional hazards regression) of resection-chemotherapy stage II/III patient group. Supplementary table 5. Statistical association between expression levels of TGF-α and EphA2 using Spearman's Rank Correlation in GSE17536, GSE39582, GSE14333 and The Cancer Genome Atlas (TCGA). Within each dataset the value of Rho and associated p-value is reported.

PDF file - 94K, Sensitivity of parental and invasive CRC cells to chemotherapy and EGFR targeted therapies.

Role of EFNA1 in invasion and migration of colorectal cancer cells.

EphA2 and overall survival in stage II and III CRC.