Functional precision medicine in colorectal cancer based on patient-derived tumoroids and in-vitro sensitivity drug testing

e15567

Background: Precision oncology based on in-vitro, functional assays has potential advantages compared to the much more common molecular approach, but the clinical benefit is unknown. We here report the results from the largest prospective interventional clinical trial testing the clinical outcome in colorectal cancer patients treated with drugs showing cytotoxic effect in matched patient-derived tumoroids. Methods: This single-center, phase II trial included patients with metastatic colorectal cancer previously exposed to all standard therapies. Specimens from one to three 18-16 G core needle biopsies were manually dissected, enzymatically treated, cultivated, and incubated to form 3D spherical microtumors, i.e. tumoroids. In the assay for in-vitro sensitivity testing, the tumoroids were challenged with single drugs and combinations thereof to determine patient-specific responses. Using tumoroid screening technology (IndiTreat, 2cureX, Copenhagen, Denmark), results were generated by comparing the sensitivity of the individual patient’s tumoroids with a reference panel from other patients. The testing included standard cytostatics and drugs with proven effect in previous early-phase clinical trials, a total of 15 drugs. The primary endpoint was the fraction of patients with progression-free survival (PFS) at two months. Based on placebo arms in randomized last-line trials, a minimal relevant difference of 20% (20% to 40%) was stated. Using Simon's two-stage design, a sample size of 45 patients was calculated with at least 14 PFS at two months (significance 5%, power 90%). Results: Ninety patients were enrolled from 9/2017 to 9/2020. Biopsies from 82 patients were obtained and sent for tumoroid formation of which 44 (54%, 95% CI 42-65) were successful and at least one treatment was suggested. Thirty-four patients initiated treatment according to the response obtained in the drug assays within a median of 51 days from inclusion (IQR 39-63). The primary endpoint, PFS at two months, was met in 17 of 34 patients (50%, 95%CI 32-68). There were no radiological responses. Median PFS was 81 days (95% CI 51-112) and median OS was 189 days (95% CI 103-277). Conclusions: Precision oncology using a functional approach with patient-derived tumoroids and in-vitro drug sensitivity testing seems feasible. The approach is limited by the fraction of patients with successful tumoroid development. The primary endpoint was met, as half of the patients were without progression at two months. Further clinical studies are justified. Clinical trial information: NCT03251612.

The clinical impact of MicroRNA-21 in low rectal cancers treated with curative radiotherapy in the organ preserving setting

e16120

Background: Neoadjuvant chemoradiotherapy (CRT) in curatively intended doses may result in clinical complete response (cCR) in selected patients, allowing for non-surgical management (NSM) of patients with low rectal cancers. MicroRNA-21-5p (miR-21), ubiquitous upregulated in cancer, has been associated with treatment response in rectal cancers treated with standard preoperative CRT. The aim of the present study was to investigate this association in low rectal cancers treated in the NSM setting. Methods: Forty eight patients from our single-arm phase II trial (NCT00952926) were available for analyses. All patients had resectable, T2 or T3, N0–N1, low adenocarcinomas and received 65Gy (intensity-modulated radiotherapy plus brachytherapy boost) and oral tegafur-uracil. Patients with cCR 6 weeks after treatment (clinical examination, magnetic-resonance imaging and biopsy) were referred to observation and followed closely. The miR expression, in the diagnostic biopsies, was measured by qPCR in 20 µl reactions using TaqMan MicroRNA Assays. The protocol using custom RT and preamplification pools was followed. The miR-193a-5p, -27a and –let7g were used for normalization based on previous recommendations from our group. The relationship between miR-21 expression and cCR was assessed using the Wilcoxon rank-sum tests. Results: Thirty-eight patients achieved cCR after treatment and were followed in observation while 10 patients proceeded to surgery due to a non-cCR. MicroRNA-21 was successfully analyzed in all samples. The median tumor expression of miR-21 in patients proceeding to surgery was significantly higher compared to patients achieving cCR, 24.3 (95% confidence interval (CI) 17.1-36.8) and 16.6 (95% CI 13.9-21.1), p = 0.02, respectively. Conclusions: The present results support a clinical impact of miR-21 in rectal cancer treated with CRT, comparable with results seen in patients treated in the standard preoperative setting, and may assist in the selection of patients for an organ preserving approach.

Validation of tumor DNA in bronchial lavage as a diagnostic tool in lung cancer

9020

Background: Diagnosing lung cancer requires invasive procedures with risk of complications for the patient. The HOXA9 gene is highly methylated in lung cancer, and methylated tumor DNA (meth-tDNA) in bronchial lavage has previously shown potential as a diagnostic biomarker. The aim of the present study was to validate these preliminary results. Methods: Patients were referred by the general practitioner on suspicion of lung cancer. The Danish diagnostic package includes chest and abdominal CT scan, bronchoscopy, blood tests, and histopathological or cytological verification. Twelve ml lavage fluid was collected at bronchoscopy for analysis of meth-tDNA based on droplet digital PCR according to our published method. A positive test was defined as ≥ 4 droplets containing meth-tDNA and a ratio between HOXA9 and Albumin of > 0.15%. The analysis was performed blinded to clinical data and meth-tDNA status was compared with the final diagnosis. Results: The study population was 204 consecutively enrolled patients. The material consisted of a discovery cohort (n = 105, presented at ASCO 2019) used for establishing the cut-points, and a validation cohort (n = 99). Six were excluded from analysis due to malignancy other than lung cancer and one due to failed analysis. In the discovery cohort, the sensitivity was 68.7% (95% CI 56.2-79.4%), specificity 88.2% (95% CI 72.6-96.7%), and positive predictive value (PPV) 92.0% (95% CI 80.8-97.8%). In the validation cohort, the same values were 76.9% (95% CI 63.2-87.5%), 77.3% (95% CI 62.2-88.5%), and 80.0% (95% CI 66.3-90.0%), respectively. Analyzing the entire patient material (n = 197) the sensitivity, specificity, and PPV were 72.3% (95% CI 63.3-80.1%), 82.1% (95% CI 71.7-89.8%), and 86.0% (95% CI 77.6-92.1%), respectively. The false positive samples were equally distributed among patients with cryptogenic organizing pneumonia, granulomatous inflammation, and acute inflammatory disease. The false negative samples were mainly from patients with peripheral tumor, no radiologically detectable tumor, and mesothelioma. Conclusions: Meth-tDNA in bronchial lavage holds potential as a supplementary tool in the diagnosis of lung cancer with a clinically relevant sensitivity and specificity. Routine clinical application awaits further validation in a clinical trial. [Table: see text]

Prognostic impact of SOX9 in stage II colon cancer: Results from a large nationwide cohort

183

Background: Up-regulation of the transcription factor SOX9 has been described in colon cancer, and it has been argued that differences in the expression levels dictates cell proliferation. The aim of the present study was to analyze the prognostic impact of SOX9 in patients with stage II colon cancer. Methods: Individual patient data and formalin fixed paraffin embedded tumor tissue were collected from a large unbiased, population-based cohort, representing all patients operated for stage II colon cancer in Denmark in 2002 and 2003. The SOX9 expression was evaluated by immunohistochemistry on whole tumor sections. Patients were classified into three groups dependent on the SOX9 expression gradient in the tumor: luminal, peripheral, and uniform for comparison with the clinical data. The endpoint was disease free survival (DFS). Results: A total of 1,153 patients were included. We detected an expression-dependent relationship between SOX9 and prognosis. Patients with tumors exhibiting a luminal expression pattern (N = 267, increasing SOX9 expression towards the luminal compartment of the tumor) were characterized by a significantly better DFS compared to the uniform (N = 846) and peripheral (N = 40) patterns, p = 0.0070. The five-year DFS rates were 74%, 67%, and 56%, respectively. Multiple Cox regression analysis, confirmed an independent prognostic advantage of the luminal SOX9 expression pattern, as compared to the uniform pattern, hazard ratio (HR) 0.7211 (95% confidence interval (CI) 0.5561-0.9351), p = 0.0137, whereas the possible disadvantage of the periphery pattern could not be verified, p = 0.1405. Conclusions: The present results support a prognostic impact of SOX9 in stage II colon cancer. The consequence of an altered SOX9 expression seems to differ between intra-tumoral compartments, and we propose that a gradient-dependent evaluation should be applied to provide the most clinically relevant information about this transcription factor.

Long-term outcomes after high-dose chemoradiotherapy for non-surgical management of distal rectal cancer

3611

Background: Surgery is standard treatment for rectal cancer, but neoadjuvant chemoradiotherapy (CRT) may result in clinical complete response (cCR) in selected patients, allowing for non-surgical management (NSM). Prospective studies of NSM strategies are sparse however, and long-term data on quality of life (QoL) are limited. We conducted a single-arm phase II trial of high-dose CRT for NSM of distal rectal cancer; we report secondary long-term patient-reported outcomes (PROs), local regrowth and overall survival (OS) in patients managed non-surgically. Methods: Fifty-one patients with resectable, T2 or T3, N0–N1, low adenocarcinoma received 65Gy (IMRT, brachytherapy boost) and oral tegafur-uracil. Patients with cCR 6 weeks after treatment (clinical examination, MRI, biopsy) were referred for observation, and followed closely with clinical examinations, endoscopies, PET-CTs, and PROs for 5 years. Overall colorectal cancer specific QoL and specific symptom scores were compared between timepoints using paired Wilcoxon tests. Local regrowth was estimated using cumulative incidence; overall survival using Kaplan-Meier estimates. Results: Forty patients achieved cCR after treatment; 28 were in follow-up at 24m, 21 at 36m, 18 at 60m. Patients left the trial due to local tumor regrowth (n=12), distant metastases (n=3), new primary cancers (n=6) and loss to follow-up (n=1). Average QoL score did not differ between baseline (median 11.1) and 24m (13.7), 48m (11.1,) or 60m (6.9). See Table for individual scores; only rectal bleeding deteriorated from baseline (significantly worse at 24m). At median follow-up of 5.0 years, local regrowth rate and OS were 31% (95 CI 15%-47%) and 85% (95 CI 75%-97%), respectively. Conclusions: Long term follow-up after NSM of early rectal cancer showed excellent general colorectal cancer QoL and local symptom scores. (NCT00952926). EORTC QLQ – CR 29. Proportion reporting ‘quite a bit’ or ‘very much’ on symptom scales. Clinical trial information: NCT00952926. [Table: see text]

Tissue immune response in epithelial ovarian carcinoma

2625

Background: Epithelial ovarian cancer (EOC) is a highly malignant disease with a fatal outcome for most patients. During recent years immunological mechanisms have proven important in relation to the treatment and prognosis of cancer, but within EOC the knowledge is still sparse. Understanding the importance of immune markers to the prognosis of ovarian cancer is essential for the future treatment of EOC. The aim of the present study was to investigate the prognostic impact of intratumoral PDL-1 expression, T cells, neutrophil granulocytes (NG) and Natural Killer (NK) cells in a population based cohort. Methods: All patients diagnosed with ovarian cancer in Denmark in 2005 were included in the study. Immunohistochemical staining was performed on tumor tissue from 412 patients. Antibodies for PD-L1, T cells (CD8), NG (CD66b), and NK cells (CD57) were used. Cell densities were analyzed using a digital image analysis method. The primary endpoint was overall survival (OS). Results: In high grade serous carcinoma (HGSC) the median OS in patients with a high level of tumor infiltrating T cells was 37 vs 25 months in patients with a low level(p = 0.0008). Multivariate analysis showed a hazard ratio (HR) of 0.72 (p = 0.020). The median OS in patients with a high level of tumor infiltrating NK cells was 45 vs 29 months in patients with a low level (p = 0.0310). Multivariate analysis showed a HR of 0.67 (p = 0.041). PD-L1 and NG had no statistically significant impact on OS. Only T cells showed prognostic significance across histological subtypes with a HR of 0.72 (p = 0.007) in favor of a high density of T cells. Conclusions: The present population based study demonstrated prognostic importance of tumor infiltrating T cells and NK cells in HGSC. Neither PD-L1 nor NG held prognostic significance.

Prognostic impact of SOX9 in stage II colon cancer: Results from a large nationwide cohort

e15165

Background: Up-regulation of the transcription factor SOX9 has been described in colon cancer, and it has been argued that differences in the expression levels dictates cell proliferation. The aim of the present study was to analyze the prognostic impact of SOX9 in stage II colon cancer. Methods: Individual patient data and formalin fixed paraffin embedded tumor tissue were collected from a large unbiased, population-based cohort, representing all patients operated for stage II colon cancer in Denmark in 2002 and 2003. The SOX9 expression was evaluated by immunohistochemistry on whole tumor sections. Patients were classified into three groups dependent on the SOX9 expression gradient in the tumor: luminal, peripheral, and uniform for comparison with the clinical data. The endpoint was disease free survival (DFS). Results: A total of 1,153 patients were included. We detected an expression-dependent relationship between SOX9 and prognoses. Patients with tumors exhibiting a luminal expression pattern (N = 267, increasing SOX9 expression towards the luminal compartment of the tumor) were characterized by a significantly better DFS compared to the uniform (N = 846) and peripheral (N = 40) patterns, p = 0.0070. The five-year DFS rates were 74%, 67%, and 56%, respectively. Multiple Cox regression analysis, adjusted for all standard high risk factors, confirmed an independent prognostic advantage of the luminal SOX9 expression pattern, as compared to the uniform pattern, hazard ratio (HR) 0.7211 (95% confidence interval (CI) 0.5561-0.9351), p = 0.0137, whereas the possible disadvantage of the periphery pattern could not be verified, HR 1.4393 (95% CI 0.8869-2.3660), p = 0.1405. Conclusions: The present results support a prognostic impact of SOX9 in stage II colon cancer. The consequence of an altered SOX9 expression seems to differ between intra-tumoral compartments, and we propose that a gradient-dependent evaluation should be applied to provide the most clinically relevant information about this transcription factor.

Tumor specific DNA in bronchial lavage as a new diagnostic tool in lung cancer

3047

Background: A considerable fraction of lung cancer patients raise diagnostic challenges requiring invasive procedures with a certain risk of complications. Therefore, new diagnostic tools are of major interest. Aberrant methylation of the HOXA9 gene occurs in almost all malignant lung tumors and HOXA9 methylated DNA (meth-ctDNA) is shed into the circulation. The present study aimed at a prospective investigation of the possible diagnostic value of HOXA9 meth-ctDNA in bronchial lavage (BL). Methods: Patients enrolled were referred from the general practitioner suspecting lung cancer. The diagnostic package according to national guidelines includes chest and abdominal CT scan, bronchoscopy, relevant blood tests, and histopathological or cytological verification. Twelve ml liquid was collected at bronchoscopy for analysis of meth-ctDNA based on ddPCR technology according to our published method. The analysis was performed blinded to the clinical data and compared to the final diagnosis. Results: Eighty-nine patients were consecutively included from the 1 November 2018 to 31 January 2019. Fifty-six patients (62.9%) were diagnosed with lung cancer and 33 (37.1%) with a variety of benign diseases. Meth-ctDNA was found in 42/56 of the patients with a malignant tumor, sensitivity = 75.0% (95%CI=61.6-85.6%), whereas 31/33 of the patients without cancer were negative, specificity = 93.9% (95%CI= 79.8-99.3%). Table summarizes the results. The false negative samples were mainly from patients with peripheral tumors. The two false positive patients included one patient with Cryptogenic Organizing Pneumonia and one with unspecific nodule. Conclusions: The presence of meth-ctDNA in BL has a high sensitivity and specificity. If validated, the analysis represents a valuable adjunct in the diagnosis of lung cancer. Potentially, it could save the patients from numerous examinations with potential harmful risks and ensure a fast diagnosis. The relation between meth-ctDNA and final lung cancer diagnosis (N= 89). [Table: see text]

Natural killer cell activity: A test for immune reactivity with clinical perspectives

87

Background: Natural Killer (NK) cells are essential in the biological fight against cancer and the activity of these cells has been suggested as a biomarker for immunological reaction in cancer patients. An assay has been introduced to measure NK cell activity (NKA) in a simple and standardized manner. Following stimulation of NK cells in whole blood with a recombinant protein, it utilizes the concentration of interferon-gamma (IFNγ) in plasma as a surrogate marker for NKA. This study aimed to verify that the test was indeed measuring NKA and whether it could predict the response to cytostatic treatment in metastatic colorectal cancer (mCRC). Methods: Blood was collected in dedicated tubes (NK Vue Promoca) and placed at 37°C. After 24 hours the plasma was analyzed for IFNγ by ELISA (NK Vue ELISA). Blood from patients with mCRC (n = 22) were sampled at baseline and prior to each treatment cycle, and IFNγ levels were compared to response data from first evaluation. The protocol is ongoing hence the results are preliminary. In healthy controls (n = 8), IFNγ was measured intracellularly using flow cytometry at baseline and after 5-, 10-, 15-, 20-, 24-, and 28 hours of incubation. Results: When analyzing the distribution of cells among the IFNγ expressing subset, the proportion of NK cells was significantly different than that of monocytes, T-, and NKT cells at all time points of incubation (p < 0.0001), thus suggesting that the readout of the test was indicative of the NK cells´ ability to mount a response. Using the NKA test, plasma levels of IFNγ in healthy controls were all above 200pg/mL after 24 hours of incubation. The mCRC patients were divided into three NKA groups: 1) IFNγ dropped below 200pg/mL or remained below that level throughout treatment (n = 9), 2) IFNγ remained above 200pg/mL throughout treatment (n = 5), and 3) IFNγ changed from being below 200pg/mL to above that level during treatment (n = 8). The response rates were 11%, 40%, and 100%, respectively, and the difference was significant (p < 0.001). The positive and negative predictive values of increasing IFNγ were 100% and 79%. Conclusions: These data suggest that increasing NK cell activity during treatment has predictive potential in mCRC. The NKA test performs reliably in this setting. Clinical trial information: NCT02705300.

Postponement of death weighed against duration of treatment and toxicity as key components in shared decision making about last line oncologic treatment

e21555

Background: Decisions about last-line treatment are challenging in oncology practice. The hope of prolonging life and reducing symptoms should be weighed against the time spend on treatment, side effects and cost. Standard oncology measures of effect such as median survival time and number needed to treat are not easily explained to patients. Postponement of symptoms or death has been shown to be superior to e.g. number needed to treat in communicating the benefit of treatment to patients. The aim of the present study was to develop a tool for shared decision making in last line treatment of patients with colorectal cancer. Methods: A literature review identified pivotal phase III trials about specific antineoplastic agents for metastatic colorectal cancer after standard treatments. Principles for determining the mean survival followed restricted mean survival time analysis. High-resolution survival curves were digitalized. Areas under the curves (AUC) were calculated for the experimental group and the control group. Results: Two drugs are approved for colorectal cancer after exposure to standard treatments; regorafenib and TAS102. AUC at one year for regorafenib was 30.1 weeks compared to 26.6 weeks for placebo resulting in a difference of 3.5 weeks. AUC at one year for TAS102 was 31.4 weeks compared to 25.7 weeks for placebo resulting in a difference of 5.7 weeks. Average time on treatment was 12 weeks for regorafenib and 14 weeks for TAS102. Risk of severe, medical significant or life-threatening (grade 3-4) adverse events increased from 14% to 54% (regorafenib) and from 52% to 69% (TAS102). Conclusions: Data was developed for shared decision making using restricted mean survival time. A patient with colorectal cancer after standard treatment can be advised: »This is a deadly disease irrespective of treatment. On average, taking medicine for about 12 weeks will postpone death for 4 to 6 weeks. Taking the medicine will cause 17 to 40 extra patients out of 100 experiencing severe or life-threatening side effects«. The concept of postponement will be further explored as a key component in patient empowerment for value based care.

Monitoring the effect of first-line treatment in RAS/RAF mutated metastatic colorectal cancer by serial analysis of tumor specific DNA in plasma

3593

Background: Personalized medicine calls for an early indicator of treatment failure. Circulating tumor DNA (ctDNA) is a promising marker in this setting and our prospective study explored the association between disease control and change of ctDNA during first line chemotherapy in patients with RAS/RAF mutated metastatic colorectal cancer (mCRC). Methods: The present study included 138 mCRC patients receiving standard first line combination chemotherapy. In patients with a RAS/RAF mutated tumor the same mutation was quantified in the plasma using droplet digital PCR (ddPCR). The fractional abundance of ctDNA (ctDNA level) was assessed in plasma before treatment start and at every treatment cycle until radiologically defined progressive disease (PD). Results: RAS/RAF mutations were detected in the plasma from 77 patients (94% of patients with a tumor mutation). Twenty patients progressed on treatment and 57 stopped treatment without progression. The presence of a RAS/RAF mutation in plasma correlated to overall survival (OS) with a median of 24.2 months for patients with a wild-type tumor compared to 12.7 months for patients with a mution in plasma. A substantial increase in ctDNA level was highly associated with progression on treatment (risk ratio = 4.58, 95%CI = 1.99-10.51, p < 0.0001). Furthermore, with a stable ctDNA level the chance of non-progression was 88.2% (range 76.1-95.6%). The first substantial increase in ctDNA level occurred at a median of 51 days (range 14-133 days) before radiologically confirmed PD. Conclusions: The results indicate that ctDNA level may be predictive of treatment effect in patients with mCRC. An increase was observed to correlate with high risk of progression with a relevant lead time, whereas an unchanging ctDNA level related to stable disease.

Monitoring tumor specific mutations in plasma during systemic treatment of biliary tract cancer

318

Background: We have previously reported a rate of 23% RAS/RAF mutations in plasma from patients with KRAS exon 2 and 3 wild-type, non-resectable biliary tract tumors. We wanted to explore the changes in circulating tumor specific DNA (ctDNA) during systemic chemotherapy in these patients. Methods: Patients with non-resectable biliary tract cancer treated within a phase II trial were included if they had KRAS exon 2 and 3 wild-type tumor tissue, had quantifiable levels of tumor specific DNA in plasma and progressive disease on imaging. They received gemcitabine, oxaliplatin and capecitabine with either bevacizumab or panitumumab. Treatment continued for up to six months until progression. Blood sampling and evaluation according to RECIST 1.1 were done every 12 weeks. Droplet Digital PCR was performed on DNA isolated from 4 ml plasma. A pre-amplification step was done and adequate positive and negative controls were included. The extended RAS and BRAF mutation analysis covered 20 mutations in KRAS exons 3/4, NRAS exon 2/3, PIK3CA and BRAF V600E. The percentage of tumor specific DNA relative to total DNA was reported. Results: The inclusion criteria were met by 13 patients, 10 women and three men. The typical pattern was seen in eight cases, where the percentage of tumor specific DNA dropped at least half during therapy and rose at least two-fold at progression. In three patients, a baseline sample was not available or there was not an initial drop, but the ctDNA rose at progression. One patient had an initial drop, but not a rise a progression based on imaging. The last patient progressed rapidly. Conclusions: This exploratory analysis pointed toward changes in percentage of tumor specific mutations in plasma as a marker of effect and progression. Dynamics of liquid biopsies is a promising tool in monitoring biliary tract cancer patients during systemic therapy. Clinical trial information: NCT01206049.

The relationship between microRNA-126 and maintenance therapy with bevacizumab after bevacizumab plus chemotherapy as first-line treatment for patients with metastatic colorectal cancer: Results of the phase III Nordic ACT trial NCT00598156 translational study

3573

Background: Maintenance therapy during chemotherapy free intervals is a debatable topic in metastatic colorectal cancer (mCRC). In the Nordic ACT trial patients benefitting from induction chemotherapy plus bevacizumab were randomized to bevacizumab with or without erlotinib. MicroRNA-126 (miRNA-126) is believed to influence angiogenesis in several ways, and we investigated the relationship between miRNA-126 and progression free survival (PFS) under maintenance therapy. Methods: The miRNA-126 was analysed by polymerase chain reaction on both genomic DNA (by the pri-miRNA-126 (A24G) single nucleotide polymorphism (SNP)) and paraffin embedded primary tumors, (which were classified as low or high miRNA-126 expressing tumours using the median value as cut-off). Diagnostic biopsies were not processed due to limited tumour tissue. Of the 159 randomized patients blood samples were available from 151 and primary tumours from 91. The PFS (from time of randomization) was compared using the Kaplan-Meier method and the log rank test. The Cox Regression analyses were used to test for independent contributions. Results: The A24G SNP was not related to PFS, but a significant association was seen between genotypes and miRNA-126 expression levels.Furthermore, the PFS was increased in patients with high tumor miRNA-126 expression compared to patients with low expression, hazard ratio (HR) 0.58 (95% confidence interval (CI) 0.38-0.90), p = 0.015. The median PFS was 6.2 months (95% CI 4.3-6.6 months) and 4.0 months (95% CI 2.6-4.5 months), respectively. Results did not differ between treatment arms, but the Cox Regression analysis confirmed an independent prognostic value of the tumor miRNA-126 expression, HR 0.61 (95% CI 0.39-0.95), p = 0.030. Conclusions: The miRNA-126 may be a potential marker for bevacizumab containing maintenance therapy. A similar relationship with PFS has recently been demonstrated in patients with mCRC treated with chemotherapy only. The results call for validation.

The prognostic value of an early response in chemoradiation of locally advanced rectal cancer

e14134

Background: Preoperative chemoradiation is standard treatment of locally advanced rectal cancer, and there is an obvious need for new methods of assessing the effect. Evaluation by clinical examination with endoscopy is controversial. In most papers the assessment of effect has been performed after the end of treatment. The aim of the present study was to investigate the clinical value of an examination during chemoradiation. Methods: The study included 128 patients with histopathologically verified rectal cancer. Further inclusion criteria were a T3 tumor with a circumferential margin ≤ 5 mm by MRI or a T4 tumor, a distance of < 10 cm from the anal verge and localized diseased only by abdominal and chest CT scan. The treatment was 50.4 Gy/28 fractions or the same treatment with the addition of endorectal brachytherapy 10 Gy/2 fractions in a randomized trial. The concomitant chemotherapy was UFT 300 mg/m2 and L-leucovorin 22.5 mg daily. Both drugs were given five days a week. Clinical examination with endoscopy was performed week 4 during treatment. The clinical effect was classified into complete response (CR) or not complete response with clinical residual tumor (NCR). The patients were operated eight weeks after end of treatment and the pathological tumor response was classified according to Mandard (TRG). Results: CR was found in 14% of the patients. Comparison with TRG showed that 82% with CR had TRG1 as compared to the NCR group where only 9% had TRG1 (p<10-4). The risk of lymph node metastasis was also different with 94% pN0 in the group with CR compared to 57% in the NCR group (p=0.02). The rate of CR translated to a major difference in the risk of recurrence (local and distant). No patients with CR experienced recurrence as compared to 19% in the NCR group (p<0.05). The CR also correlated with cancer specific survival. None of the patients with CR died from rectal cancer with a median observation time of 36 months compared to 30% in the NCR group. Conclusions: CR is a major prognostic parameter in locally advanced rectal cancer treated with chemoradiation. Early CR should be considered in the selection of patients for Watchful Waiting.

The prognostic importance of miRNA-21 in stage II colon cancer: A population-based study

3513

Background: Adjuvant chemotherapy for stage II colon cancer patients is still controversial and the debate on which patients should be considered as high risk patients is still ongoing. The decision is based on clinical and pathological markers of risk, which are inadequately informative in most of the patients, and better methods are highly needed. The aim of the present study was to investigate the possible prognostic importance of miRNA-21, quantified by in situ hybridization (ISH), in a unique, large population-based cohort of patients treated for stage II colon cancer patients. Methods: The study included all patients diagnosed with stage II colon cancer in Denmark in the year 2003 (711 patients), representing a full population of five million people. Patients receiving adjuvant chemotherapy were excluded (N=15). One paraffin-embedded tissue block was obtained from each patient. A 6μm-thick section was processed for formazan-based chromogenic miR-21 ISH analysis and counter stained with nuclear red. The blue miR-21 ISH signal was assessed by image analysis to obtain two quantitative expression estimates: the total blue area (TB) and the ratio of TB with the nuclear density (TBR). Results: The miRNA-21 signal was predominantly observed in fibroblast-like cells located in the stromal compartment of the tumors. Patients expressing high levels of miRNA-21 (high mean TBR) had significantly inferior cancer specific survival (CSS): HR = 1.26 (95% CI; 1.15-1.60), p <0.001. In the COX regression analysis (including; gender, T-category, malignancy grade, localization, tumor perforation, tumor fixation, number of lymph nodes and MSI status), mean TBR was found to be an independent predictive marker of poor CSS, HR = 1.41 (95%CI; 1.19-1.67, p< 0.001). The same applied to TB. Conclusions: The present study shows that increasing miRNA-21 expression level is significantly correlated to decreasing CSS. Analyses of miRNA-21 should be considered as a potential adjunct in the selection of high risk stage II patients.

Panitumumab and pegylated liposomal doxorubicin in platinum-resistant epithelial ovarian cancer with KRAS wild-type: The PaLiDo study, a phase II nonrandomized multicenter study

5052

Background: Ovarian cancer (OC) patients with platinum-resistant recurrent disease have few therapeutic options and the response rates are only 10-20% using non-cross-resistant chemotherapeutic agents. The increasing number of negative trials for OC treatment has prompted an evaluation of new biologic agents, which in combination with chemotherapy may result in improvement in survival. Panitumumab is a fully human monoclonal antibody specific to the epidermal growth factor receptor (EGFR). No previous studies have evaluated the effect of panitumumab in OC based on KRAS mutation status. The main purpose was to investigate the response rate in platinum-resistant, KRAS wild-type OC patients treated with pegylated liposomal doxorubicin (PLD) supplemented with panitumumab. Methods: Major eligibility criteria were confirmed stage I-IV primary epithelial ovarian/fallopian/peritoneal cancer patients with progression either during or within 6 months after end of first or second line platinum-based chemotherapy. Only patients with measurable disease by CA125 criteria and with KRAS wild type were eligible. Patients were treated with panitumumab 6 mg/kg day 1 and day 15 and with PLD 40 mg/m² day 1, every 4 weeks. Tumor assessment was performed at baseline and at every third cycle according to CA-125 criteria. Results: A total of 46 patients were enrolled by 6 study sites in this multi-institutional phase II trial. Within the population evaluable for response (N=33), there was 8 CA125 responders for an overall response rate of 24.3 %. Progression-free and overall survival in the intention-to-treat population (N=43) was 2.7 months (2.5-3.2 months, 95%CI) and 8.1 months (5.6-11.7 months, 95%CI), respectively. The most common treatment related grade 3 toxicities included skin toxicity (42%), fatigue (19%) and vomiting (12%). Conclusions: The combination of PLD and panitumumab demonstrates efficacy in platinum refractory/resistant patients although the dermatologic toxicity was considerable.