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Missense mutations in the TP53tumor-suppressor gene inactivate its antitumorigenic properties and endow the incipient cells with newly acquired oncogenic properties that drive invasion and metastasis. Although the oncogenic effect of mutant p53 transcriptome has been widely acknowledged, the global influence of mutant p53 on cancer cell proteome remains to be fully elucidated. Here, we show that mutant p53 drives the release of invasive extracellular factors (the ‘secretome’) that facilitates the invasion of lung cancer cell lines. Proteomic characterization of the secretome from mutant p53-inducible H1299 human non-small cell lung cancer cell line discovered that the mutant p53 drives its oncogenic pathways through modulating the gene expression of numerous targets that are subsequently secreted from the cells. Of these genes, alpha-1 antitrypsin (A1AT) was identified as a critical effector of mutant p53 that drives invasion in vitroand in vivo,together with induction of epithelial–mesenchymal transition markers expression. Mutant p53 upregulated A1AT transcriptionally through the involvement with its family member p63. Conditioned medium containing secreted A1AT enhanced cell invasion, while an A1AT-blocking antibody attenuated the mutant p53-driven migration and invasion. Importantly, high A1AT expression correlated with increased tumor stage, elevated p53 staining and shorter overall survival in lung adenocarcinoma patients. Collectively, these findings suggest that A1AT is an indispensable target of mutant p53 with prognostic and therapeutic potential in mutant p53-expressing tumors.

Alanine, serine, cysteine-preferring transporter 2 (ASCT2; SLC1A5) mediates uptake of glutamine, a conditionally essential amino acid in rapidly proliferating tumour cells. Uptake of glutamine and subsequent glutaminolysis is critical for activation of the mTORC1 nutrient-sensing pathway, which regulates cell growth and protein translation in cancer cells. This is of particular interest in breast cancer, as glutamine dependence is increased in high-risk breast cancer subtypes. Pharmacological inhibitors of ASCT2-mediated transport significantly reduced glutamine uptake in human breast cancer cell lines, leading to the suppression of mTORC1 signalling, cell growth and cell cycle progression. Notably, these effects were subtype-dependent, with ASCT2 transport critical only for triple-negative (TN) basal-like breast cancer cell growth compared with minimal effects in luminal breast cancer cells. Both stable and inducible shRNA-mediated ASCT2 knockdown confirmed that inhibiting ASCT2 function was sufficient to prevent cellular proliferation and induce rapid cell death in TN basal-like breast cancer cells, but not in luminal cells. Using a bioluminescent orthotopic xenograft mouse model, ASCT2 expression was then shown to be necessary for both successful engraftment and growth of HCC1806 TN breast cancer cells in vivo. Lower tumoral expression of ASCT2 conferred a significant survival advantage in xenografted mice. These responses remained intact in primary breast cancers, where gene expression analysis showed high expression of ASCT2 and glutamine metabolism-related genes, including GLUL and GLS, in a cohort of 90 TN breast cancer patients, as well as correlations with the transcriptional regulators, MYC and ATF4. This study provides preclinical evidence for the feasibility of novel therapies exploiting ASCT2 transporter activity in breast cancer, particularly in the high-risk basal-like subgroup of TN breast cancer where there is not only high expression of ASCT2, but also a marked reliance on its activity for sustained cellular proliferation.

IntroductionTwo groups of biological therapies are licensed and approved by NICE for the management of moderate to severe UC in the UK. The anti-TNF drugs, Infliximab (IFX), Adalimumab (ADA) and Golimumab and the α4β7 anti-integrin Vedolizumab (VDZ). As there are no published head-to-head RCTs comparing the efficacy and safety of these drugs for UC, we aim to compare the outcomes for all patients treated with biological therapy for UC in our unit of 3000 IBD patients.MethodAnti-TNF or VDZ has been used routinely for UC maintenance therapy in Leeds since Oct 2015. We use biosimilar IFX as our first line anti-TNF, ADA for patients who prefer SC over IV therapy and VDZ for anti-TNF failures or contraindications. Acute severe colitis cases were excluded. We prospectively collected data on demographics and clinical outcomes over a 9 month period. Response and remission at 3 months were defined according to Mayo scores or physician global assessment (PGA) and compared using the Chi-squared test.ResultsA total of 36 (20 female) patients received biological therapy for UC in this period (17 IFX, 6 ADA, 13 VDZ). Baseline results for IFX:ADA:VDZ respectively are; mean age (years) 38, 30, 41; disease duration (months) 92.8, 23.4, 54; mean weight (kg) 74, 80, 81; mean steroid dose (mg) 10.5, 1.6, 15; and thiopurine use 59%, 33%, 62%. Mayo scores at baseline were 6.4, 7.3, 7 or with endoscopy sub-scores 8.5 (n=14), 9.5 (n=2), 9 (n=8).17/17 (100%) IFX patients were given the drug first line compared to 4/6 (67%) ADA and 2/13 (15%) VDZ. VDZ was used first-line in 1 case of MS and 1 of possible latent TB. After 3 months of IFX therapy 1 dose escalated, 3 switched to ADA due to low drug levels with high antibodies and 2 had treatment withdrawn due to infusion reactions. 50% of ADA patients dose escalated by 3 months. There were 4 colectomies in the VDZ group, all had previously failed ≥1 anti-TNF therapy. There was no significant difference in response (p=0.17) and remission (p=0.62) rates between IFX and VDZ.Abstract PWE-053 Table 1Response (Resp) and Remission (Rem) rates by Mayo score or PGA for biological therapies in UCDrugnResp MayoResp PGARem MayoRem PGAColectomyIFX178/13 (62%)12/17 (71%)7/13 (54%)9/17 (53%)0ADA63/6 (50%)3/6 (50%)0/5 (0%)1/6 (17%)0VDZ139/13 (69%)9/13 (69%)5/13 (38%)4/13 (31%)4ConclusionAnti-TNF and VDZ therapies are safe and effective in the management of UC. Whilst patient numbers were small 50% of ADA patients dose escalated, this is of particular note considering the relative cost of these therapies. VDZ response and remission rates of 69% and 38% are encouraging in this largely anti-TNF failure cohort, however more data on cost-effectiveness of anti-TNF versus VDZ first-line are required.Disclosure of InterestA. Johnston: None Declared, M. Lenti: None Declared, A. O’Connor: None Declared, C. Selinger Conflict with: Warner Chilcott, Abbvie, Conflict with: Warner Chilcott, Dr Falk, Abbvie, Takeda, Janssen, Conflict with: Warner Chilcott, Dr Falk, Abbvie, MSD, Takeda, A. Ford: None Declared, P. Hamlin Conflict with: Abbvie, Dr Falk, Ferring, Janssen, MSD, Otsuka, Takeda Warner Chilcottee

IntroductionVirtual biologics clinics (VBC) are used to review annually patients receiving biological therapy. Decisions on continuing, switching or stopping therapy are based on review of clinical symptoms, disease history and investigations. Therapeutic drug monitoring (TDM) of Infliximab trough levels (ITL) and anti-drug antibodies (ADA) has previously not been universally available in the UK. The aim of this study was to assess whether access to TDM influences decision making within VBC.MethodAll IBD patients receiving Infliximab maintenance therapy were reviewed and two treatment decisions were recorded. The first decision was based on assessment of all clinical details but clinicians remained blinded to ITL and ADA data (Biohit assay). An administrator revealed ITL and ADA data and clinicians formed a second decision incorporating TDM. Decisions were standardised to: A - continue without change B -shorten infusion interval/increase IFX dose C - lengthen infusion interval D - stop IFX E - other.N= blindN= unblindedA169 122B9 16C5 15D5 28E3 122ResultsOf 201 patients reviewed TDM data were available for 191 (mean 40y old, 57% male). Diagnoses were Crohn’s disease in 160, ulcerative colitis in 18 and IBD-U in 13 cases. Mean duration of IFX treatment was 4 years (minimum 6 months), 57% received co-therapy with immunomodulator and 38% had shortened infusion intervals. Disease activity was remission in 70%, mild in 19%, moderate in 10% and severe in 1%. ITL were sub-therapeutic in 25% (<1.8 mg/L), therapeutic in 61% and supra-therapeutic in 14% (>7 mg/L); mean ITL was 3.85 mg/L. ADA were detected in 30% and were >50 AU/ml in 14%. Blinded treatment decisions were changed on unblinded review in 56 cases (29%, table 1, chi-square test: p<0.0001). Knowledge of ITL and ADA led to 7 patients receiving higher dose IFX or more frequent infusions whereas 33 patients were able to dose de-escalate or stop IFX therapy.DecisionConclusionBasing decisions on TDM rather than clinical acumen alone led to change in 29%. An additional 23 patients discontinued therapy (undetectable ITL + high ADA). This represents a considerable cost saving and reduces the exposure to potentially toxic therapies. Routine TDM should be considered as an integral part of VBC.Disclosure of InterestNone Declared

IntroductionIntroduction of biologics particularly anti-TNF agents are thought to have resulted in changes in natural history of Crohn’s disease (CD). The impact of these in presentation of CD with perianal fistula (CD-PAF) and subsequent surgical approaches is not known.Method11 IBD centres across Europe and Israel were invited to collect data on CD-PAF patients diagnosed since January 2010 to Dec 2015. Data on demographics, mode and route of presentation, type of fistula, MRI, prior treatment for CD were collected. Patients who had at least one surgical therapy for CD-PAF fistula were analysed for reasons and the type of interventions.Results253 patients with CD-PAF (161 M, 92 F) were included. The mean age at diagnosis of CD was 28 years (SD: 13.3), and at diagnosis of CD-PAF was 32 years (SD: 13.92). 65% of the patients with CD-APF developed their fistulae in the period between 1 year before and 4 years after diagnosis of CD. 30% of patients were smokers at the onset of CD-PAF. 37.2% of the CD-PAF presented as emergency medical or surgical admission and 30% and 23.7% were identified in IBD clinics and colorectal clinics respectively. 77.1% has MRI pelvis done at diagnosis with 52.8% of patients having complex fistulae (38.7% trans-sphincteric, 10.3% extrasphincteric,3.8% with suprasphincteric).Proctitis and anal stenosis at presentation were identified in 43.1% and 9.5% respectively. Examination under Anaesthesia (EUA) +/- abscess drainage was required in 69.6% of patients but only 53.8% had Seton inserted at first EUA (median number of Setons=1, range 1–6). 96 patients (68% of those needing Seton insertion) had them removed and only 33 of these needed Seton re-insertion. he reasons for non-removal:surgeons’ preference (21);surgeon and physician preference (13) and patient preference (5).Overall repeat surgical intervention were required in 102 patients (40.3%):repeat abscess drainage (43), Reinsertion of Seton (33), Diverting stoma (20) and proctectomy (6).ConclusionMajority of CD-PAF present within 5 years of their diagnosis of CD with a third presenting as emergency. EUA with abscess drainage and Seton insertion is the main surgical intervention needed. Radical surgery appears to be less often requiring in comparison to previous studies.Disclosure of InterestNone Declared

IntroductionTreatment paradigms for Crohn’s disease with perianal fistula (CD-PAF) are still evolving and so far, considered to have disappointing rates of complete healing. We aimed to study the impact of multidisciplinary multimodality treatment approach in CD-PAF on the recurrence rates of fistula and need for re-interventions.MethodThis was a multinational multicentre retrospective cohort study with data collected in CD patients who developed fistula from 2010 to 2015. Multidisciplinary multimodality approach was defined as using a combination of medical treatments (antibiotics, immunomodulators, and biologics) along with surgical approach (examination under anaesthesia (EUA) +/- Seton drainage) at diagnosis.Results253 adult onset CD-PAF patients were included. There was significant difference in fistula healing rates between simple and complex fistulae (complete healing 60% vs 41%, p=0.015). 52% of patients who received multimodality treatment had complete fistula healing. 27% of simple fistula and 40.3% of the complex patients had recurrent fistula needing re-intervention at a median of 12 months (range 1–36 months) from diagnosis of fistula. 22% of those with complete healing needed repeat surgery compared to 49% with partial healing and 71% in those with no healing (p=<0.001). Only 26% of the 141 patients having multidisciplinary multimodal treatment needed surgical re-intervention when compared to 59% without this( P=<0.001).Univariate analysis showed complex (p=0.008),absence of multidisciplinary approach (p=<0.001), EUA (p=0.005),combined immunosuppression (p=0.032),presence of proctitis (p=<0.001) as factors impacting need for re-intervention but there was no impact of age, gender, smoking status, mode of presentation,Montreal class, presence of anal stenosis and thiopurine use alone. On logistic regression, absence of multi-disciplinary approach (OR 2.8, 95% CI: 1.4–5.6) and presence of proctitis OR 2.2, 95% CI: 1.2, 3.9) were predictors for re-intervention.ConclusionIn this multicentre cohort study, complete fistula healing rates were higher and the recurrence rates lower than previously reported. Presence of proctitis and lack of multidisciplinary approach are predictors for recurrence and re-intervention for CD-PAF.Disclosure of InterestNone Declared

IntroductionThere is no comparative data on outcomes in perianal fistulas in paediatric/adolescent versus adult onset CD. Management paradigms in perianal fistulas in Crohn’s disease is not fully defined and approaches from paediatric and adult IBD clinicians and surgeons may be different. We aimed to study any differences in diagnostic and treatment approaches and outcomes in paediatric/adolescent onset CD with perianal fistula (CD-PAF) and adult onset disease.MethodData was collected on patients included in 2 retrospective multicentre multinational cohorts (11 adult and 7 paediatric centres) of perianal fistula with paediatric/adolescent onset and adult onset CD PAF. We evaluated fistula characteristics, surgical and medical treatments following onset of CD-PAF and fistula healing. We also compared re-intervention rates:the need for re-insertion of seton or abscess drainage or diverting stoma or proctectomy.Results253 adults and 116 paediatric/adolescent patients were included. Complex fistulas were identified in 53% of adult and 67% of paediatric/adolescent group. Proctitis was recorded in 43% of adult onset and in 3% of paediatric/adolescent onset CD-PAF. Significantly higher proportion of adult CD-PAF patients had seton insertion (15% vs 54%, p<0.001). Anti TNF use was more often is paediatric onset CD-PAF (83% vs 68%). Complete clinical fistula healing was more often noted in paediatric/adolescent onset CD-PAF (71% vs 49%, p=0.015). Reintervention rates were higher in adult onset CD (40.3% vs 16.05%, p=<0.001. Radical surgery (diverting stoma or proctectomy) was required in 3 patients (2.58%) with paediatric/adolescent onset and 26 patients (10.28%) with adult onset CD-PAF (p=0.04).ConclusionPaediatric/adolescent onset CD-PAF appears to have better outcomes with less radical surgery or re-interventions when compared to adult onset disease despite less frequent use of seton.Disclosure of InterestNone Declared

IntroductionFor the majority of patients with IBD long-term therapy is required to maintain remission; yet 30%–45% of patients do not adhere to their IBD medication. Medication adherence can be assessed with prescription refill rates, biological measures (metabolites, trough levels, etc) and patient self-report tools. There is currently no accepted gold standard and the feasibility and utility of different adherence assessment tools in the routine outpatient clinic setting has not been fully examined. The aim of this service improvement project was to test the acceptability of self-report tools assessing thiopurine adherence in the IBD clinic and to correlate the results with thioguanine-nucleotide (TGN) levels.MethodConsecutive outpatients on thiopurine maintenance therapy for IBD for >3 months were recruited from clinic. Patients self-reported adherence using a visual analogue scale (VAS), the validated Morisky adherence tool (MOR) and the validated Medication Adherence Report Scale (MARS). TGN levels were classed as complete non-adherence (<100 and MMP low), partial adherence (TGN 100–235 and MMP low) or full adherence (>235 or MMP high). Correlation analysis was performed using Pearson tests.ResultsOf 100 approached patients none refused participation and TGN levels were available for 69. These included 38 women. Diagnoses were Crohn’s disease in 27, ulcerative colitis in 41 and IBD-U in 1 cases. Concomitant therapy included 5-ASA (25 cases), anti-TNF (13 cases) and Vedolizumab (2 cases). The proportion of adherent patients was according to the relevant report tool 71% (TGN), 87% (VAS), 87% (Morisky) and 77% (MARS). VAS (Pearson 0.315; p=0.005) and Morisky (Pearson −0.363; p=0.001) correlated moderately with TGN, but MARS (Pearson 0.09; p=0.39) did not. The 7 patients, who were non-adherent by TGN were detected by VAS in 3, Morisky in 6 and MARS in 3 cases. However, patients showing non-adherence according to self-report tools had normal TGN levels in 6 of 10 cases for VAS, 10 of 26 for Morisky and 4 of 15 for MARS.ConclusionSelf-report tools provided a patient friendly and inexpensive way of assessing adherence, but correlation with TGN levels was only moderate. While providing a more objective assessment TGN levels are problematic for routine use in all patients. TGN require a more invasive and expensive approach. Furthermore TGN cannot detect “white coat adherence” (patients take medication only around appointments), which is the most likely explanation for normal TGN levels in patients reporting to be poorly adherent. Neither TGN levels nor self-report tools can be seen as the gold standard at present.Disclosure of InterestNone Declared