Vital Tumor Cells Research Articles

761 PATIENT PREFERENCES FOR ACTIVE SURVEILLANCE VERSUS STANDARD SURGERY AFTER NEOADJUVANT CHEMORADIOTHERAPY IN ESOPHAGEAL CANCER TREATMENT

Abstract The need for standard surgical resection in esophageal cancer patients after neoadjuvant chemoradiotherapy (nCRT) is subject of debate. Possibly, active surveillance (AS) is an option for patients with a clinically complete response (cCR), in whom no vital tumor cells are detected after nCRT. In a large Dutch multicenter randomized trial (SANO trial), standard surgery is compared to AS in patients with a cCR. Within this trial, we performed a side-study on patient treatment preferences. Methods Esophageal cancer patients, who declined participation in the SANO-trial due to a strong treatment preference for either AS or surgery were included. In-depth interviews were held on patient’s motives for their treatment choice. First, personal motives were addressed in an open manner, and later specific topics were addressed: earlier experiences with illness and health care, future health expectations, emotional motives, religious or spiritual believes and values in life. Data was recorded, transcribed verbatim and qualitatively analyzed according to the grounded theory principles. In addition, questionnaires on health literacy, coping, anxiety and decision regret were administered at two time points. Results Forty patients participated: twenty preferred AS and twenty standard surgery. The central principle for all patients is striving for safety while dealing with the threat of cancer. However, patients express different coping strategies in dealing with this threat. Patients preferring AS rely on trusting their bodies and good outcomes, while questioning the need for surgery. Patients preferring surgery try to minimize insecurity by eliminating the source of the cancer, while arguing that chances for undergoing surgery are high anyway. Interestingly, for either treatment option comparable arguments were used, with the most striking one of wishing ‘not to become a patient’. Conclusion Patients’ preferences in the treatment of esophageal cancer are determined by the way they cope with the threat of cancer. Since the arguments given for either AS or standard surgery can be comparable or even similar, the need for healthcare professionals to discuss what truly matters to their patients is of high importance. Subsequently, attuning to the personal needs of esophageal cancer patients will benefit the decision making process on future treatment.

Computertomography-Based Prediction of Complete Response Following Neoadjuvant Chemoradiotherapy of Locally Advanced Rectal Cancer.

Therapeutic strategies for patients with locally advanced rectal cancer (LARC) who are achieving a pathological complete response (pCR) after neoadjuvant radio-chemotherapy (neoCRT) are being increasingly investigated. Recent trials challenge the current standard therapy of total mesorectal excision (TME). For some patients, the treatment strategy of “watch-and-wait” seems a preferable procedure. The key factor in determining individual treatment strategies following neoCRT is the precise evaluation of the tumor response. Contrast-enhanced computer tomography (ceCT) has proven its ability to discriminate benign and malign lesions in multiple cancers. In this study, we retrospectively analyzed the ceCT based density of LARC in 30 patients, undergoing neoCRT followed by TME. We compared the tumors´ pre- and post-neoCRT density and correlated the results to the amount of residual vital tumor cells in the resected tissue. Overall, the density decreased after neoCRT, with the highest decrease in patients achieving pCR. Densitometry demonstrated a specificity of 88% and sensitivity of 68% in predicting pCR. Thus, we claim that ceCT based densitometry is a useful tool in identifying patients with LARC who may benefit from a “watch-and-wait” strategy and suggest further prospective studies.

Targeted therapy of human leukemia xenografts in immunodeficient zebrafish

Personalized medicine holds tremendous promise for improving safety and efficacy of drug therapies by optimizing treatment regimens. Rapidly developed patient-derived xenografts (pdx) could be a helpful tool for analyzing the effect of drugs against an individual’s tumor by growing the tumor in an immunodeficient animal. Severe combined immunodeficiency (SCID) mice enable efficient in vivo expansion of vital tumor cells and generation of personalized xenografts. However, they are not amenable to large-scale rapid screening, which is critical in identifying new compounds from large compound libraries. The development of a zebrafish model suitable for pdx could facilitate large-scale screening of drugs targeted against specific malignancies. Here, we describe a novel strategy for establishing a zebrafish model for drug testing in leukemia xenografts. We used chronic myelogenous leukemia and acute myeloid leukemia for xenotransplantation into SCID zebrafish to evaluate drug screening protocols. We showed the in vivo efficacy of the ABL inhibitor imatinib, MEK inhibitor U0126, cytarabine, azacitidine and arsenic trioxide. We performed corresponding in vitro studies, demonstrating that combination of MEK- and FLT3-inhibitors exhibit an enhanced effect in vitro. We further evaluated the feasibility of zebrafish for transplantation of primary human hematopoietic cells that can survive at 15 day-post-fertilization. Our results provide critical insights to guide development of high-throughput platforms for evaluating leukemia.

Cancer Stem Cells: Current Status and Therapeutic Implications in Cancer Therapy-A New Paradigm.

Recent evidence confirms that not each tumor cell is proficient in instigating a tumor. Merely a small part of the cancer cells, so-called cancer stem cells (CSCs), can produce cancer indistinguishable from the first one. CSC model has been recognized as a cellular component that adds to phenotypic and functional heterogeneity in different cancers. The latest explanations have featured numerous complexities and difficulties like CSC phenotype that can differ extensively between patients. Tumors may harbor various phenotypically or genetically specific CSCs, and consequently, metastatic CSCs can develop from vital CSCs and tumor cells. Scientists have discovered a few markers for CSCs. The recent finding reveals that CSCs are resistant to radiotherapy and chemotherapy and may clarify the disease's reappearance. Minimal amounts of CSCs can repopulate a tumor. Subsequently, it is essential to understand the attributes and mechanisms by which CSCs show their resistance to therapeutic agents. These aptitudes contribute to new bits of knowledge that give better therapeutic motivations to discover novel anticancer therapeutics. Accordingly, remedial procedures that emphasize focusing on CSCs and their microenvironmental niche are insufficient for conventional malignant growth treatments to eradicate the CSCs that, in any case, bring about therapy resistance. Mutual utilization of traditional therapies with CSC- specific agents may offer a promising technique for enduring cancer treatment as well as remedy.

Histopathologic Regression and Survival in RAS Wildtype Metastatic Colorectal Cancer Under First-Line Treatment – Subgroup Analysis of the VOLFI Trial (AIO-KRK-0109)

<i>Aim</i>: The VOLFI trial demonstrated an improved objective response rate through the addition of panitumumab to FOLFOXIRI in untreated all-RAS-wildtype mCRCs compared to FOLFOXIRI alone. In this subgroup analysis, we focused on histopathological response as a predictive marker for PFS. Additionally, we analyzed chemotherapy induced steatosis hepatitis (CASH) in both treatment arms. <i>Methods</i>: Histopathological response, CASH, sinusoidal obstructive syndrome, ballooning, steatosis, cholestasis, fibrosis and inflammation were determined in 14 resected liver metastasis. PFS was estimated using Kaplan-Meier method, the logrank test was used for the statistical comparison. The trial is registered with Clinical Trials. gov, NCT01328171. <i>Results</i>: Tissue of 14/18 resected pts. was evaluable. Median age was 57.5 yrs. (32–67), 7 male and 7 females. All primary tumors were located in the left colon. Molecular analysis detected one BRAF V600E mutation and one MSI-H tumor. Median treatment duration until resection were 7 cycles (3 – 12) panitumumab/mFOLFOXIRI and 9.5 cycles (7 - 11) FOLFOXIRI. 7 pts. achieved very good histopathological response corresponding to ≤20% vital tumor cells (panitumumab/ mFOLFOXIRI vs. FOLFOXIRI 2/5) and 7 pts. showed vital tumor cells >20% (panitumumab/mFOLFOXIRI vs. FOLFOXIRI 2/5). A very good histopathological response (residual tumor cells in proportion to the total tumor area ≤20%) showed a trend to an improved PFS in comparison to >20% (median PFS 12.40; 95% CI 6.43-51.22 vs. PFS 9.88; 95% CI 6.17-15.26 months). The severity of CASH was not increased by the addition of panitumumab or longer duration of chemotherapy. <i>Discussion</i>: In this analysis histopathological response seems to correlate with a better PFS after secondary metastasis resection. By analysis of liver toxicity, no relevant difference of CASH were detectable regarding panitumumab/mFOLFOXIRI vs. FOLFOXIRI or the duration of chemotherapy.

Postneoadjuvant surveillance and surgery as needed compared with postneoadjuvant surgery on principle in multimodal treatment for oesophageal cancer: a scoping review protocol

IntroductionIn current medical practice of curative treatment for non-metastatic oesophageal cancer, surgery on principle is carried out by oesophagectomy after neoadjuvant treatment. However, oesophagectomy is often associated with postoperative morbidity...

Enhanced prognostic stratification of neoadjuvant treated lung squamous cell carcinoma by computationally-guided tumor regression scoring

IntroductionThe amount of residual tumor burden after neoadjuvant chemotherapy is an important prognosticator, but for non-small cell lung carcinoma (NSCLC), no official regression scoring system is yet established. Computationally derived histological regression scores could provide unbiased and quantitative readouts to complement the clinical assessment of treatment response. MethodsHistopathologic tumor regression was microscopically assessed on whole cases in a neoadjuvant chemotherapy-treated cohort (NAC, n = 55 patients) of lung squamous cell carcinomas (LSCC). For each patient, the slide showing the least pathologic regression was selected for subsequent computational analysis and histological features were quantified: percentage of vital tumor cells (cTu.Percentage), total surface covered by vital tumor cells (cTu.Area), area of the largest vital tumor fragment (cTu.Size.max), and total number of vital tumor fragments (cTu.Fragments). A chemo-naïve LSCC cohort (CN, n = 104) was used for reference. For 23 of the 55 patients [18F]-Fluorodeoxyglucose (FDG) PET/CT measurements of maximum standard uptake value (SUVmax), background subtracted lesion activity (BSL) and background subtracted volume (BSV) were correlated with pathologic regression. Survival analysis was carried out using Cox regression and receiver operating characteristic (ROC) curve analysis using a 3-years cutoff. ResultsAll computational regression parameters significantly correlated with relative changes of BSV FDG PET/CT values after neoadjuvant chemotherapy. ROC curve analysis of histological parameters of NAC patients showed that cTu.Percentage was the most accurate prognosticator of overall survival (ROC curve AUC = 0.77, p-value = 0.001, Cox regression HR = 3.6, p = 0.001, variable cutoff < = 30 %). ConclusionsThis study demonstrates the prognostic relevance of computer-derived histopathologic scores. Additionally, the analysis carried out on slides displaying the least pathologic regression correlated with overall pathologic response and PET/CT values. This might improve the objective histopathologic assessment of tumor response in neoadjuvant setting.

Ex vivo modelling of drug efficacy in a rare metastatic urachal carcinoma

BackgroundEx vivo drug screening refers to the out-of-body assessment of drug efficacy in patient derived vital tumor cells. The purpose of these methods is to enable functional testing of patient specific efficacy of anti-cancer therapeutics and personalized treatment strategies. Such approaches could prove powerful especially in context of rare cancers for which demonstration of novel therapies is difficult due to the low numbers of patients. Here, we report comparison of different ex vivo drug screening methods in a metastatic urachal adenocarcinoma, a rare and aggressive non-urothelial bladder malignancy that arises from the remnant embryologic urachus in adults.MethodsTo compare the feasibility and results obtained with alternative ex vivo drug screening techniques, we used three different approaches; enzymatic cell viability assay of 2D cell cultures and image-based cytometry of 2D and 3D cell cultures in parallel. Vital tumor cells isolated from a biopsy obtained in context of a surgical debulking procedure were used for screening of 1160 drugs with the aim to evaluate patterns of efficacy in the urachal cancer cells.ResultsDose response data from the enzymatic cell viability assay and the image-based assay of 2D cell cultures showed the best consistency. With 3D cell culture conditions, the proliferation rate of the tumor cells was slower and potency of several drugs was reduced even following growth rate normalization of the responses. MEK, mTOR, and MET inhibitors were identified as the most cytotoxic targeted drugs. Secondary validation analyses confirmed the efficacy of these drugs also with the new human urachal adenocarcinoma cell line (MISB18) established from the patient’s tumor.ConclusionsAll the tested ex vivo drug screening methods captured the patient’s tumor cells’ sensitivity to drugs that could be associated with the oncogenic KRASG12V mutation found in the patient’s tumor cells. Specific drug classes however resulted in differential dose response profiles dependent on the used cell culture method indicating that the choice of assay could bias results from ex vivo drug screening assays for selected drug classes.

Does multiparametric imaging with 18F-FDG-PET/MRI capture spatial variation in immunohistochemical cancer biomarkers in head and neck squamous cell carcinoma?

BackgroundThe purpose of this study is to test if functional multiparametric imaging with 18F-FDG-PET/MRI correlates spatially with immunohistochemical biomarker status within a lesion of head and neck squamous cell carcinoma (HNSCC), and also whether a biopsy with the highest FDG uptake was more likely to have the highest PD-L1 expression or the highest percentage of vital tumour cells (VTC) compared with a random biopsy.MethodsThirty-one patients with HNSCC were scanned on an integrated PET/MRI scanner with FDG prior to surgery in this prospective study. Imaging was quantified with SUV, ADC and Ktrans. A 3D-morphometric MRI scan of the specimen was used to co-register the patient and the specimen scans. All specimens were sectioned in consecutive slices, and slices from six different locations were selected randomly from each tumour. Core biopsies were performed to construct TMA blocks for IHC staining with the ten predefined biomarkers. The spatial correlation was assessed with a partial correlation analysis.ResultsTwenty-eight patients with a total of 33 lesions were eligible for further analysis. There were significant correlations between the three imaging biomarkers and some of the IHC biomarkers. Moreover, a biopsy taken from the most FDG-avid part of the tumour did not have a statistically significantly higher probability of higher PD-L1 expression or VTC, compared with a random biopsy.ConclusionWe found statistically significant correlations between functional imaging parameters and key molecular cancer markers.

Histopathology of retinoblastoma eyes enucleated after intra-arterial chemotherapy

BackgroundTo demonstrate histopathological findings in retinoblastoma eyes enucleated after intra-arterial chemotherapy (IAC) with special emphasis on vascular toxicity and local tumour control.MethodsRetrospective study with a consecutive series of 23 retinoblastoma...

904PD - Pre-operative ipilimumab and nivolumab in locoregionally advanced, stage III, urothelial cancer (NABUCCO)

BackgroundStage III (cT3-4aN0M0 or ≥cT1N+M0) urothelial cancer (UC) patients (pts) have a poor prognosis. Despite high response rates, pre-operative chemo shows limited survival benefit. Immunotherapy targeting PD-1/PD-L1 is active in metastatic UC; the combination of ipilimumab (ipi) and nivolumab (nivo) appears to increase response rates. Encouraging path Complete Response (pCR) rates are observed in trials testing neoadjuvant anti-PD-1/PD-L1 (mostly cT2-T3N0 pts). Here, we present the first clinical trial data on preoperative ipi+nivo. MethodsThis is a single-arm phase 1B trial testing the feasibility (primary endpoint) of pre-operative ipi+nivo in stage III UC pts (cis unfit/refusal). To mitigate the risk of immune-related toxicity, pts were treated with (based on melanoma data): ipi 3mg/kg (day 1), ipi 3 + nivo 1mg/kg (day 22), and nivo 3mg/kg (day 43), followed by resection. Secondary endpoints were efficacy (pCR) and translational parameters: PD-L1, TMB (by WES), and immune cell infiltrates at baseline vs on-treatment using multiplex immunofluorescence (mIF; pan-CK/CD3/CD8/FOXP3/CD20/CD68). Results24 pts (14 cT3-4N0; 10 cN+) were enrolled, of whom 23 (96%) had resection <12 weeks from 1st cycle. 1pt, responding radiologically, had a delay in surgery because of an irAE (hemolysis). 18/24 pts received all 3 cycles, 6 pts received 2 cycles due to irAEs. Grade 3/4 irAEs occurred in 54% of pts; 42% when excluding clinically insignificant lab deviations. 22 pts were available for efficacy assessment (1pt resection delayed, 1pt had resection 1day before abstract submission). 10/22 pts (45%) achieved a pCR. 3 additional pts (14%) had noninvasive cancer at resection (2 ypTis, 1 ypTa), resulting in an overall path downstaging (≤ypT1N0) rate of 59% (13/22). In recent neoadjuvant IO studies in melanoma and NSCLC, major path response (MPR) has been defined as≤10% vital tumor cells in the tumor bed. MPR was seen in 5/22 pts (23%). Nonresponse was seen in 4/22 (17%). Response was associated with massive infiltration of CD8+ T-cells in the tumour bed. ConclusionsPreoperative ipi+nivo is feasible (96% surgery <12 weeks) and shows promising efficacy in stage III UC pts. Updated results on all 24 pts, including mIF, PDL1 and TMB, will be presented. Clinical trial identificationNCT03387761, January 2, 2018. Legal entity responsible for the studyNetherlands Cancer Institute - Antoni van Leeuwenhoek. FundingBMS. DisclosureM.S. Van der Heijden: Advisory / Consultancy, Research grant / Funding (institution): BMS; Advisory / Consultancy, Research grant / Funding (institution): Astellas; Advisory / Consultancy, Research grant / Funding (institution), Travel / Accommodation / Expenses: Roche/Genentech; Advisory / Consultancy, Research grant / Funding (institution): AstraZeneca; Advisory / Consultancy, Travel / Accommodation / Expenses: MSD; Advisory / Consultancy: Janssen. T.N. Schumacher: Advisory / Consultancy: Adaptive Biotechnologies; Advisory / Consultancy, Shareholder / Stockholder / Stock options: AIMM Therapeutics; Advisory / Consultancy, Shareholder / Stockholder / Stock options: Allogene Therapeutics; Advisory / Consultancy: Amgen; Advisory / Consultancy, Shareholder / Stockholder / Stock options: Merus; Advisory / Consultancy, Shareholder / Stockholder / Stock options: Neon Therapeutics; Advisory / Consultancy, Shareholder / Stockholder / Stock options: Scenic Biotech; Advisory / Consultancy: Third Rock Ventures; Research grant / Funding (institution): Merck; Research grant / Funding (institution): Bristol-Myers Squibb; Research grant / Funding (institution): Merck KGaA. P. Kvistborg: Advisory / Consultancy: Neon Therapeutics; Advisory / Consultancy: Personalis; Research grant / Funding (institution): Merck; Research grant / Funding (institution): BMS. C.U. Blank: Advisory / Consultancy, Research grant / Funding (institution): BMS; Advisory / Consultancy: MSD; Advisory / Consultancy, Research grant / Funding (institution): Novartis; Advisory / Consultancy: Roche; Advisory / Consultancy: GSK; Advisory / Consultancy: Pfizer; Advisory / Consultancy: Eli Lilly; Advisory / Consultancy: GenMab; Advisory / Consultancy: Pierre Fabre; Research grant / Funding (institution): NanoString. B.W. van Rhijn: Advisory / Consultancy: Astellas; Advisory / Consultancy: AstraZeneca; Advisory / Consultancy: Ferring. All other authors have declared no conflicts of interest.

Efficacy of a Bispecific Antibody Co-Targeting VEGFA and Ang-2 in Combination with Chemotherapy in a Chemoresistant Colorectal Carcinoma Xenograft Model.

Vascular endothelial growth factor (VEGF) inhibition by the addition of bevacizumab to the chemotherapy regimen of metastatic colorectal cancer leads to an improved outcome. However, anti-angiogenic tumor therapy targeting a single factor may be limited by complementary mechanisms. Angiopoietin-2 (Ang-2, ANGPT2) is another important factor that cooperates with VEGF to drive tumor angiogenesis. It was shown that high Ang-2 levels are associated with a poor clinical outcome of colorectal cancer patients treated with bevacizumab-containing therapy. Therefore, combined inhibition of VEGF and Ang-2 was supposed to improve anti-angiogenic therapy. Here, we evaluated the efficacy of a bispecific antibody (CrossMab) co-targeting VEGF and Ang-2 in combination with chemotherapy in a chemoresistant colorectal carcinoma model. Antitumor activity was evaluated in athymic nude mice bearing subcutaneous DLD1 xenograft tumors and treated with anti-VEGF (B20), anti-Ang-2 (LC06) and anti-VEGF/Ang-2 (CrossMab) antibodies. Chemotherapy consisted of 5-FU and irinotecan. Resected tumors were analyzed immunohistochemically. First, an impact of targeting each single factor but also a clear advantage of co-targeting both factors could be demonstrated. Accordingly, tumor tissue showed strong staining for VEGF and Ang-2. Chemotherapy alone was less effective. Efficient tumor growth inhibition could be achieved by treatment with anti-VEGF/chemotherapy, single CrossMab and CrossMab/chemotherapy, which resulted in 3 out of 10, 6 out of 10 and 10 out of 10 complete responses, respectively, during seven weeks. Complete retarded tumors were characterized by massive intratumoral necrosis surrounded by layers of vital tumor cells and connective tissue with CD31-positive vessels at the periphery. In some cases, a distinct feature known as vessel co-option could be observed. In conclusion, the data from this model clearly support the strategy of co-targeting VEGF and Ang-2 and further demonstrate the beneficial impact of co-treatment with chemotherapy. The clear superiority of the CrossMab-containing regimen compared to clinical standard anti-VEGF/chemotherapy warrants further analyses in other models.

PET-directed combined modality therapy for gastroesophageal junction cancer: First results of the prospective MEMORI trial.

4018 Background: We evaluated a PET-guided treatment stratification for improvement in obtaining negative surgical margins (R0) in resectable gastroesophageal junction (GEJ) adenocarcinoma. According to sequential 18F-FDG PET, only 40–50% of patients (pts) respond to neoadjuvant chemotherapy (CTX). Early PET non-responders (P-NR) after induction CTX might benefit from changing to chemoradiation (CRT). Methods: 75 pts with resectable GEJ adenocarcinomas were enrolled in this interventional, prospective, non-randomized multicenter trial. Pts underwent baseline 18F-FDG PET scan followed by 1 cycle of CTX (physicians’ choice, e.g. EOX, XP, mFOLFOX6). PET was repeated at day 14-21 and responders (P-R), defined as ≥ 35% decrease in SUVmax from baseline, continued with CTX. P-NR switched to CRT (41.4 Gy/23 fractions with weekly carboplatin/paclitaxel). Pts underwent surgery 4-6 weeks post-CTX/CRT. Primary objective was an improvement of R0 resection rates in P-NR above a proportion of 70% based on results from the MUNICON1/2 trials. Secondary endpoints include disease-free survival (DFS), overall survival (OS), measured from randomization to death from any cause, and translational endpoints. Results: Between 12/2014 and 07/ 2018 160 pts with resectable GEJ adenocarcinomas were prospectively screened with PET in three German university centers. Overall, 85 pts (53%) could not be included due to previously undetectable metastases (40/25%), no or too low FDG uptake of the primary tumor (21/13%), other reasons (24/15%). 75 eligible pts were enrolled in the study and 69 were evaluable. Based on PET criteria, 47 (68%) and 22 (32%) were P-R and P-NR, respectively. R0 resection rates were 94% (44/47) for P-R and 91% (20/22) for P-NR. Pathologic complete remission (pCR; &lt; 10% vital tumor cells), was 33% (15/46) in P-R and 55% (12/22) in P-NR. With a median follow-up time of 19 months (mo), estimated 18 mo DFS was 71%/61% for P-R/P-NR, respectively. Observed median 18 mo OS was 95% for P-R and 75% for P-NR. Conclusions: Alternative CRT for GEJ adenocarcinoma improved R0- and pCR rates among pts who were P-NR after induction CTX. PET response was prognostic for a prolonged OS and DFS. Clinical trial information: 2014-000860-16.

Correlation of histopathologic regression with progression free survival (PFS) in patients (pts) with RAS wildtype metastatic colorectal cancer (mCRC) under fluorouracil/folinic acid, irinotecan, and oxaliplatin (FOLFOXIRI) plus panitumumab (pmab) or FOLFOXIRI alone: Subgroup analysis of VOLFI (AIO-KRK-0109).

e15024 Background: We recently demonstrated improved objective response rate in untreated all-RAS wildtype mCRC with the addition of the anti-EGFR-antibody pmab to FOLFOXIRI. In this subgroup analysis we focused on histopathological response as a predictive marker for PFS. Additionally we analyzed chemotherapy induced steatosis hepatitis (CASH) in both treatment arms. Methods: Tissue samples from pts. achieving secondary resection of liver metastases in VOLFI were analyzed. We defined a cut-off for very good histopathological response at 20% of residual tumor cells in proportion to the total tumor area. For CASH sinusoidal obstructive syndrome, ballooning, steatosis, cholestasis, fibrosis and inflammation were determined. PFS was estimated using LIFETEST procedure. Results: Tissue of 14/19 resected pts. was evaluable (pmab-FOLFOXIRI/FOLFOXIRI: 11/3). All showed partial remission by RECIST. Median age was 56 yrs. (32–67), male/female: 7/7. All primary tumors were located in the left colon. Molecular analysis detected 1 BRAF (V600E) mutation and 1 MSI-H tumor. Median treatment duration until resection in this cohort: pmab-FOLFOXIRI 7 cycles (3-12)/FOLFOXIRI 9.5 cycles (7-11).7 pts. achieved very good histopathological response with vital tumor cells ≤20% (pmab-FOLFOXIRI/FOLFOXIRI 5/2) and 7 pts. showed vital tumor cells &gt;20% (pmab-FOLFOXIRI/FOLFOXIRI 6/1). The cut-off correlated with an improved PFS in the group ≤20 vs &gt;20% (median PFS 12.40; confidence interval (CI) 6.43-51.22 vs PFS 9.88; CI 6.17-15.26 months). The severity of CASH was not increased by the addition of pmab. Conclusions: In this preliminary analysis of VOLFI histopathological response seems to correlate with a better PFS after secondary resection of liver metastases. There was no relevant difference in CASH between pmab-FOLFOXIRI vs. FOLFOXIRI alone. The trial is registered with ClinicalTrials.gov, NCT01328171. Clinical trial information: AIO-KRK-0109.

Neoadjuvant chemoradiation for patients with advanced oesophageal cancer - which response grading system best impacts prognostic discrimination?

Neoadjuvant chemoradiation reduces tumour volume and improves the R0 resection rate, followed by extended survival for patients with advanced oesophageal cancer. The degree of tumour regression has high prognostic relevance. To date, there is still no generally accepted tumour regression grading system. The aim of this study was to compare the prognostic discrimination power of different histological regression grading systems: (i) the fibrosis/tumour ratio within the primary tumour (Mandard classification), (ii) the percentage of residual vital tumour cells (VTC) compared to the original primary tumour (Cologne Regression) and (iii) the ypT category, in patients with cT3 carcinoma of the oesophagus after neoadjuvant chemoradiation. This study included 216 patients with oesophageal cancer clinically staged as cT3NxM0 and treated from 2009 to 2012 with standardised chemoradiation followed by oesophagectomy [median age 62years, 176 (81%) male and 138 (64%) adenocarcinoma patients]. The subgroup frequencies of the three classification systems were ypT category: ypT0=18%, ypT1=14%, ypT2=23%, ypT3= 44%, ypT4=1%; Mandard classification: TRG1=18%, TRG2=26%, TRG3=24%, TRG4= 30%, TRG5=2%; and Cologne Regression Scale: no tumour=18%, 1-10% VTC=27%, 10-50% VTC= 26% and >50% VTC=29%. The Mandard and Cologne Regression classifications showed better prognostic differentiation for the subgroups than the ypT category. The four-tiered Cologne Regression system had a good prognostic relevance. Comparing results of the re-evaluated Cologne Regression classification with the classification by routine pathological report showed very good inter-rater agreement, with kappa value 0.891. Compared to the original primary tumour, the tumour regression grading system using the percentage of residual vital tumour has prognostic relevance.

Systematic Generation of Patient-Derived Tumor Models in Pancreatic Cancer.

In highly aggressive malignancies like pancreatic cancer (PC), patient-derived tumor models can serve as disease-relevant models to understand disease-related biology as well as to guide clinical decision-making. In this study, we describe a two-step protocol allowing systematic establishment of patient-derived primary cultures from PC patient tumors. Initial xenotransplantation of surgically resected patient tumors (n = 134) into immunodeficient mice allows for efficient in vivo expansion of vital tumor cells and successful tumor expansion in 38% of patient tumors (51/134). Expansion xenografts closely recapitulate the histoarchitecture of their matching patients’ primary tumors. Digestion of xenograft tumors and subsequent in vitro cultivation resulted in the successful generation of semi-adherent PC cultures of pure epithelial cell origin in 43.1% of the cases. The established primary cultures include diverse pathological types of PC: Pancreatic ductal adenocarcinoma (86.3%, 19/22), adenosquamous carcinoma (9.1%, 2/22) and ductal adenocarcinoma with oncocytic IPMN (4.5%, 1/22). We here provide a protocol to establish quality-controlled PC patient-derived primary cell cultures from heterogeneous PC patient tumors. In vitro preclinical models provide the basis for the identification and preclinical assessment of novel therapeutic opportunities targeting pancreatic cancer.

Treatment of hepatic pancreatic ductal adenocarcinoma metastases with high-dose-rate image-guided interstitial brachytherapy: a single center experience.

PurposeTo evaluate the efficacy and safety of image-guided (computed tomography/magnetic resonance imaging – CT/MRI) high-dose-rate (HDR) interstitial brachytherapy (iBT) as a salvage maneuver for the treatment of hepatic metastases originating from hepatic pancreatic ductal adenocarcinoma (PDAC). PDAC metastases present a major and unresolved problem, and any surgical approach or local therapeutic intervention remains extremely controversial.Material and methodsA cumulative number of 45 hepatic PDAC metastases in 16 patients were treated and retrospectively analyzed. Synchronous metastatic spread was observed in five patients, metachronous in eleven. 14 patients had resection of the pancreatic primary prior to iBT: eight Whipple/PPPD and six distal pancreatectomy procedures. The hepatic metastases were progressing under chemotherapy, thus iBT was applied as a salvage maneuver with the intention of local tumor control and prolonged survival. iBT is applied interstitially, with temporarily introduced 192Ir source in a single fraction HDR irradiation regime to eradicate vital tumor cells. Response to treatment was assessed clinically with CT/MRI every three months.ResultsLocal tumor control was achieved in 87% of all treated metastases. The median diameter of the irradiated lesions was 2.2 cm (range, 1-11.2 cm), the median irradiation dose was 21 Gy (range, 5-29.1 Gy). Median progression-free survival (PFS) after iBT was 3.4 months (range, 1.5-19.6 months), the median overall survival (OS) after iBT was 8.9 months (range, 3.1-29.3 months). Three major complications (CTCAE grade 3) occurred following iBT: three cases of liver abscess, which were successfully resolved with drainage and antibiotics.ConclusionsOverall, iBT is a safe procedure, which enables excellent rates of local tumor control and presents a viable anti-neoplastic treatment option as a salvage therapy for metastatic PDAC patients.

Expression levels of hnRNPK and p21WAF1/CIP1 are associated with resistance to radiochemotherapy independent ofp53 pathway activation in rectal adenocarcinoma.

Ionizing radiation (IR) is frequently applied in the treatment of rectal adenocarcinoma, however, there is marked variance in the response to radiochemotherapy between individual tumors. In our previous investigations, it was shown that the overexpression of heterogeneous nuclear ribonucleoprotein K (hnRNP K) confers radioresistance to malignant melanoma and colorectal carcinoma (CRC) in vitro, however, the underlying mechanism remains to be elucidated. As hnRNP K, a p53 binding partner and cofactor for the transcriptional activation of p53 target genes, is overexpressed in CRC, the present study investigated the possible radioprotective effect of the hnRNP K/p53-induced upregulation of p21 (also known as WAF1/CIP1) in rectal adenocarcinoma. Immunohistochemistry was performed for hnRNP K, p53 and p21 in a series of 68 consecutive cases of rectal adenocarcinoma with full molecular characterization following radiochemo-therapy and 14 corresponding pre-therapeutic biopsies, and the results were correlated with clinicopathological characteristics and the percentage of vital tumor cells following therapy. In addition, pathway analyses, protein immunoprecipitation, western immunoblotting and immunofluorescence microscopy were performed to identify dysregulated kinase signaling and hnRNP K targets upon exposure of CRC cells to IR. Although the fraction of vital tumor cells upon neoadjuvant therapy was significantly higher in hnRNP K/p21-positive tumors (P=0.0047 and P=0.0223, Students’ t-test), no significant association was found between the protein expression levels of hnRNP K, p53 and p21 (P>0.05, χ2 test). Irradiation enhanced apoptotic pathway activation via p53/CHK2 phosphorylation and poly (ADP-ribose) polymerase cleavage, and induced the overexpression and interaction of hnRNP K and p53. However, p53 Ser15-phosphorylation was independent of the presence of hnRNP K, and there was no measurable effect of hnRNP K on the expression of p21 in vitro. Taken together, the results of the present study support a radioprotective role for hnRNP K, which may be mediated through an interaction with p53, however, this effect appears to be independent of the hnRNP K/p53-induced upregulation of p21 in rectal adenocarcinoma.

PS02.085: ASSESSMENT OF TUMOR REGRESSION OF ESOPHAGEAL SQUAMOUS CELL CARCINOMA AFTER NEOADJUVANT CHEMORADIOTHERAPY: COMPARISON OF 3 COMMONLY USED SCORING APPROACHES

Abstract Background Tumor regression grade (TRG) is a measure of histopathological response of cancer to neoadjuvant chemoradiotherapy(nCRT) and is associated with outcomes. Several TRG system are used in esophageal cancer: Schneider 4 tier(0%,1∼10%,10∼50%, &gt; 50% vital residual tumor cell[VRTC]), Chirieac 3 tier(0%,1∼50%, &gt; 50% VRTC) and Japanese 4 tier(0%,1∼33%,33∼66%, &gt; 66% VRTC). Although these methods are generally accepted, currently there is no common standard. Methods We compared the application of three major systems for assessment of tumor regression. Hematoxylin and eosin–stained slides from 370 resection specimens of esophageal squamous cell carcinoma following nCRT were independently reviewed by two pathologists. Primary endpoints included (1) interobserver agreement (2) prognostic discrimination Results Interobserver agreement was excellent for all three sutem while the Chirieac 3 tier system showed the best kappa value(0.93). All models had similar discriminatory and stratification power, and they predicted survival (P &lt; 0.0001) on univariate analysis. While Chirieac system remained a significant predictor for overall survival independent of yp-stage and margin status in multivariate analysis. Conclusion A simple 3-tiered system with the estimation of VRTC(0%,1∼50%, &gt; 50%) is most reproducible for the evaluation of histological response and together with yp-stage and margin status as independent predictors for survival. Disclosure All authors have declared no conflicts of interest.

Correlation of Dynamic O-(2-[18F]Fluoroethyl)-L-Tyrosine Positron Emission Tomography, Conventional Magnetic Resonance Imaging, and Whole-Brain Histopathology in a Pretreated Glioblastoma: A Postmortem Study

Amino acid positron emission tomography (PET) using O-(2-[18F]fluoroethyl)-L-tyrosine (FET) provides important additional information on the extent of viable tumor tissue of glioblastoma compared with magnetic resonance imaging (MRI). Especially after radiochemotherapy, progression of contrast enhancement in MRI is equivocal and may represent either tumor progression or treatment-related changes. Here, the first case comparing postmortem whole-brain histology of a patient with pretreated glioblastoma with dynamic invivo FET PET and MRI is presented. A 61-year-old patient with glioblastoma initially underwent partial tumor resection and died 11 weeks after completion of chemoradiation with concurrent temozolomide. Three days before the patient died, a follow-up FET PET and MRI scan indicated tumor progression. Autopsy was performed 48 hours after death. After formalin fixation, a 7-cm bihemispherical segment of the brain containing the entire tumor mass was cut into 3500 consecutive 20μm coronal sections. Representative sections were stained with hematoxylin and eosin stain, cresyl violet, and glial fibrillary acidic protein immunohistochemistry. An experienced neuropathologist identified areas of dense and diffuse neoplastic infiltration, astrogliosis, and necrosis. Invivo FET PET, MRI datasets, and postmortem histology were co-registered and compared by 3 experienced physicians. Increased uptake of FET in the area of equivocal contrast enhancement on MRI correlated very well with dense infiltration by vital tumor cells and showed tracer kinetics typical for malignant gliomas. An area of predominantly reactive astrogliosis showed only moderate uptake of FET and tracer kinetics usually observed in benign lesions. This case report impressively documents the correct imaging of a progressive glioblastoma by FET PET.