Alice Gangloff

Effects of KRAS, BRAF, NRAS, and PIK3CA mutations on the efficacy of cetuximab plus chemotherapy in chemotherapy-refractory metastatic colorectal cancer: a retrospective consortium analysis

BACKGROUND Following the discovery that mutant KRAS is associated with resistance to anti-epidermal growth factor receptor (EGFR) antibodies, the tumours of patients with metastatic colorectal cancer are now profiled for seven KRAS mutations before receiving cetuximab or panitumumab. However, most patients with KRAS wild-type tumours still do not respond. We studied the effect of other downstream mutations on the efficacy of cetuximab in, to our knowledge, the largest cohort to date of patients with chemotherapy-refractory metastatic colorectal cancer treated with cetuximab plus chemotherapy in the pre-KRAS selection era. METHODS 1022 tumour DNA samples (73 from fresh-frozen and 949 from formalin-fixed, paraffin-embedded tissue) from patients treated with cetuximab between 2001 and 2008 were gathered from 11 centres in seven European countries. 773 primary tumour samples had sufficient quality DNA and were included in mutation frequency analyses; mass spectrometry genotyping of tumour samples for KRAS, BRAF, NRAS, and PIK3CA was done centrally. We analysed objective response, progression-free survival (PFS), and overall survival in molecularly defined subgroups of the 649 chemotherapy-refractory patients treated with cetuximab plus chemotherapy. FINDINGS 40.0% (299/747) of the tumours harboured a KRAS mutation, 14.5% (108/743) harboured a PIK3CA mutation (of which 68.5% [74/108] were located in exon 9 and 20.4% [22/108] in exon 20), 4.7% (36/761) harboured a BRAF mutation, and 2.6% (17/644) harboured an NRAS mutation. KRAS mutants did not derive benefit compared with wild types, with a response rate of 6.7% (17/253) versus 35.8% (126/352; odds ratio [OR] 0.13, 95% CI 0.07-0.22; p<0.0001), a median PFS of 12 weeks versus 24 weeks (hazard ratio [HR] 1.98, 1.66-2.36; p<0.0001), and a median overall survival of 32 weeks versus 50 weeks (1.75, 1.47-2.09; p<0.0001). In KRAS wild types, carriers of BRAF and NRAS mutations had a significantly lower response rate than did BRAF and NRAS wild types, with a response rate of 8.3% (2/24) in carriers of BRAF mutations versus 38.0% in BRAF wild types (124/326; OR 0.15, 95% CI 0.02-0.51; p=0.0012); and 7.7% (1/13) in carriers of NRAS mutations versus 38.1% in NRAS wild types (110/289; OR 0.14, 0.007-0.70; p=0.013). PIK3CA exon 9 mutations had no effect, whereas exon 20 mutations were associated with a worse outcome compared with wild types, with a response rate of 0.0% (0/9) versus 36.8% (121/329; OR 0.00, 0.00-0.89; p=0.029), a median PFS of 11.5 weeks versus 24 weeks (HR 2.52, 1.33-4.78; p=0.013), and a median overall survival of 34 weeks versus 51 weeks (3.29, 1.60-6.74; p=0.0057). Multivariate analysis and conditional inference trees confirmed that, if KRAS is not mutated, assessing BRAF, NRAS, and PIK3CA exon 20 mutations (in that order) gives additional information about outcome. Objective response rates in our series were 24.4% in the unselected population, 36.3% in the KRAS wild-type selected population, and 41.2% in the KRAS, BRAF, NRAS, and PIK3CA exon 20 wild-type population. INTERPRETATION While confirming the negative effect of KRAS mutations on outcome after cetuximab, we show that BRAF, NRAS, and PIK3CA exon 20 mutations are significantly associated with a low response rate. Objective response rates could be improved by additional genotyping of BRAF, NRAS, and PIK3CA exon 20 mutations in a KRAS wild-type population. FUNDING Belgian Federation against Cancer (Stichting tegen Kanker).

Clinical value of chip-based digital-PCR platform for the detection of circulating DNA in metastatic colorectal cancer.

BACKGROUND The detection of circulating DNA is considered a promising strategy in cancer patients. Digital PCR has emerged as a sensitive method able to quantify both circulating free and tumour DNA. AIM The aim of this study was to prospectively evaluate the clinical value of a chip-based digital PCR for the detection of circulating DNA. METHODS Digital PCR was used in 34 metastatic colorectal cancer patients to detect and quantify circulating free and tumour DNA based on K-ras mutational status. Clinical outcomes were analyzed according to circulating DNA measurements. RESULTS Digital PCR yielded a detection rate of 69% for circulating tumour DNA. The median concentrations of circulating free and tumour DNA were 20 and 6.8 ng/mL, respectively, with significant correlation between both biomarkers (p<0.001). Median overall survival was 4.8 months in patients with high circulating free DNA (>75% quartile) versus not reached in patients with a low level (<25% quartile) (p=0.029). Moreover, median overall survival was significantly decreased in patients with detectable circulating tumour DNA compared to those without (respectively 11.8 months versus not reached, p=0.04). CONCLUSIONS Chip-based digital PCR is a simple and non-invasive method allowing the efficient detection of circulating DNA. Our results highlight that levels of these circulating markers may have a potential prognostic value.

Impact of nutritional parameter variations during definitive chemoradiotherapy in locally advanced oesophageal cancer

BACKGROUND Undernutrition is frequently observed in patients with a locally advanced oesophageal carcinoma. However, variations of nutritional parameters during chemoradiotherapy have not been thoroughly investigated. AIM To evaluate the characteristics and the impact of nutritional variations during treatment. METHODS Weight loss, body mass index (BMI), serum albumin level and daily food intake at baseline and during treatment (T1=week 1; T2=week 5 or 8; T3=week 11) were retrospectively analyzed in 101 patients with oesophageal carcinoma. RESULTS Significant variations occurred during chemoradiotherapy with a decrease in serum albumin level (p<0.001), body mass index (p<0.001) and weight (p<0.001). Response rate to treatment was significantly lower in patients with undernutrition at T1 (p=0.05), from T1 to T2 (p=0.01) and from T1 to T3 (p=0.04). Median overall survival was 25 months in patients with persistent undernutrition from T1 to T2 vs 42 months in wellnourished patients from T1 to T2 and those malnourished only at T1 or T2 (p=0.05). In responders, patients presenting with a lower weight or a lower food intake from T1 to T3 had worse survival (33 vs 59 months, p<0.001 and 29 vs 61 months, p=0.001, respectively). CONCLUSION Significant variations of nutritional parameters occurred during chemoradiotherapy with a worse impact on response and survival.

Fully versus partially covered self‐expandable metal stents in benign esophageal strictures

Self-expandable plastic stents are currently recommended for refractory benign esophageal strictures but they show disappointing results in terms of migration and long-term efficacy. We report here our experience in the management of benign esophageal strictures with partially covered (PCSEMS) and fully covered self-expandable metal stents (FCSEMS). We performed a retrospective analysis of self-expandable metal stent (SEMS) placements for benign esophageal strictures from 1998 to 2011 in Rouen University Hospital. Twenty-two patients (15 men, 7 women) attempted 40 esophageal SEMS placements (17 PCSEMS, 23 FCSEMS) during this period. All technical complications were migrations. Migration was noted after 3/17 PCSEMS (17.6%) and 4/23 FCSEMS placement (17.4%, P = ns). Clinical complications occurred after 6/17 PCSEMS and 2/23 FCSEMS placements (35.3% vs. 8.7%, P = 0.053). PCSEMS caused two major complications (fistulae) whereas FCSEMS did not cause any major complication (11.7% vs. 0%). Mean dysphagia score was significantly lower after SEMS placement (1.68 vs. 3.08, P < 0.001) with similar results for PCSEMS and FCSEMS. Stent placement resulted in long-term clinical success for 23.5% of PCSEMS and 34.7% of FCSEMS (P = 0.0505). FCSEMS provide satisfying clinical success rate with an acceptable complication rate and they could constitute a relevant therapeutic option in the management of benign esophageal strictures.

Diagnostic value of CA19.9, circulating tumour DNA and circulating tumour cells in patients with solid pancreatic tumours

Background:The direct comparison of CA19.9, circulating tumour cells (CTCs) and circulating tumour DNA (ctDNA) using endoscopic ultrasound-guided fine needle aspiration (EUS-FNA) has never been performed for the diagnosis of solid pancreatic tumours (SPTs).Methods:We included 68 patients with a SPT referred for EUS-FNA. CTCs were analysed using size-based platform and ctDNA using digital PCR. The sensitivity, specificity, negative and positive predictive values were evaluated for each marker and their combination.Results:SPTs corresponded to 58 malignant tumours (52 pancreatic adenocarcinoma (PA) and 6 others) and 10 benign lesions. The sensitivity and specificity for PA diagnosis were 73% and 88% for EUS-FNA, 67% and 80% for CTC, 65% and 75% for ctDNA and 79% and 93% for CA19.9, respectively. The positivity of at least 2 markers was associated with a sensitivity and specificity of 78% and 91%, respectively. CtDNA was the only marker associated with overall survival (median 5.2 months for ctDNA+ vs 11.0 months for ctDNA−, P=0.01).Conclusions:CA19.9 alone and in combination with ctDNA and/or CTC analysis may represent an efficient method for diagnosing PA in patients with SPTs. Further studies including a larger cohort of patients with both malignant and benign lesions will be necessary to confirm these promising results.

Evaluating bevacizumab in combination with FOLFIRI after the failure of platinum-etoposide regimen in patients with advanced poorly differentiated neuroendocrine carcinoma: The PRODIGE 41–BEVANEC randomized phase II study

INTRODUCTION Patients with gastroenteropancreatic (GEP), metastatic or locally advanced, non-resectable, grade 3 poorly-differentiated neuroendocrine carcinoma (NEC) are treated with cisplatin (or carboplatin)-etoposide in first-line palliative chemotherapy (CT1). However, nearly all patients will develop resistance and there is no standard second-line treatment. AIM PRODIGE 41-BEVANEC is an academic randomized, phase II study designed to evaluate the efficacy of bevacizumab in combination with FOLFIRI after failure of CT1 in unknown primary NEC and GEP-NEC. MATERIALS AND METHODS The main eligibility criteria are age ≥18 years, metastatic (synchronous or metachronous) or locally advanced, non-resectable, grade 3 GEP-NEC, and documented progressive disease during or after CT1 therapy. RESULTS A total of 124 patients will be randomly assigned (1:1) to receive either 5 mg/kg bevacizumab with FOLFIRI, or FOLFIRI alone, every 14 days until disease progression or unacceptable toxicity. The hypothesis is to demonstrate a 6-month overall survival for at least 50% of the patients in bevacizumab arm versus 35% in the control arm (FOLFIRI alone). Secondary endpoints are objective response, response duration, progression-free survival, toxicity, and biochemical response. CONCLUSION The study is currently opened in France (NCT02820857). The first patient was randomized on September 6, 2017.

Réponse à la radiochimiothérapie dans le cancer de l’œsophage : du mythe à la réalité ?

La radiochimiotherapie (RCT) seule ou suivie de chirurgie constitue une etape determinante de la prise en charge therapeutique du cancer de l’œsophage non metastatique localement avance. Plusieurs etudes randomisees ont montre un benefice de survie similaire entre la RCT definitive et la RCT suivie de chirurgie chez les patients repondeurs a la sequence de RCT initiale. L’evaluation de la reponse a la RCT est necessaire pour identifier les patients repondeurs des non repondeurs a la RCT. Classiquement, l’evaluation de la reponse s’effectue 6 a 10 semaines apres la fin de la RCT par au moins un examen d’imagerie et la realisation d’une endoscopie œsogastroduodenale (EOGD) avec biopsies de la zone traitee. La reponse clinique complete (RCC) est definie par l’absence de tumeur visible en imagerie et l’absence de residu tumoral macroscopique et histologique en EOGD avec biopsies. Si l’evaluation et la definition d’une reponse complete apres RCT a evolue au cours du temps, elle est imparfaite et de nouveaux parametres sont evalues tels que notamment la reponse metabolique par tomographie d’emission de positons au [18F]-fluorodeoxyglucose (TEP-FDG), le but principal etant de se rapprocher de la reponse pathologique. Dans ce contexte, une etude randomisee francaise (etude ESOSTRATE) va prochainement debuter afin de comparer la RCT seule a la RCT plus chirurgie chez les patients consideres en reponse complete (clinique, tomodensitometrie +/- TEP-FDG).

1617PCLINICAL INTEREST OF DIGITAL PCR FOR ROUTINE DETECTION OF CIRCULATING DNA IN METASTATIC COLORECTAL CANCER

ABSTRACT Aim: Liquid biopsy based on circulating DNA is considered as a promising issue in cancer patients to assess key somatic alterations involved in disease progression or in treatment sensitivity. However, the clinical relevance of sensitive detection methods such as Digital PCR remains to be established. The aim was to evaluate the clinical interest of Digital PCR in circulating DNA detection including cell-free (cfDNA) and circulating tumour (ctDNA) DNA in patients treated for a metastatic colorectal cancer (MCRC). Methods: A prospective single-center study was conducted from April to July 2013 in 34 patients treated for a MCRC. DNA was extracted from 1 mL of plasma using the QIAamp ® kit Circulating Nucleic Acid. ctDNA was detected and quantified (fragments per mL of plasma) by Digital PCR (Digital 3D ™ QuantStudio ®, Life Technologies) from KRAS mutations identified in the primary tumor. cfDNA was also quantified by Digital PCR and expressed in ng/mL of plasma. Response to chemotherapy and survival were analyzed according to both cfDNA and ctDNA. cfDNA was integrated as a dichotomized covariate (above versus below 75% percentile) for response and overall survival (OS) analysis. Results: The mean cfDNA concentration was 106 ng/mL (range, 3-1443 ng/mL). KRAS mutations were identified in tumour from 16/34 patients (c.34G>T, n=1; c.35G>A, n=8; c.35G>C, n=3; c.35G>T, n=2; c.38G>A, n=2) with a sensitivity and specificity for ctDNA detection of 63% (10/16) and 100% (0/18), respectively. The mean level of ctDNA was 21972 fragments/mL (range, 136 and 308,000). There was a significant correlation between cfDNA and ctDNA (r=0.993, p Conclusions: Digital PCR is a simple and non-invasive method allowing the routine detection of circulating DNA. Our results also highlight that cfDNA and ctDNA are correlate markers with a significant prognostic impact in MCRC patients. Disclosure: All authors have declared no conflicts of interest.

565PA BAR CODE OF SELECTED GENE COPY NUMBER ALTERATIONS IS ASSOCIATED WITH DISEASE-FREE SURVIVAL IN STAGE II-III MICROSATELLITE STABLE (MSS) COLON CANCER

ABSTRACT Aim: Genomic quantitative alteration is a backbone event during the carcinogenesis process in microsatellite stable colon cancer. However, the prognostic value of loss or gain of the main genomic regions is still controversial. We conducted a prospective study to assess the prognostic impact of the main genomic quantitative alterations in stage II-III MSS colon cancer (NCT02110329). Methods: Patients treated for stage II-III colon cancer from 01/2002 to 01/2009 with available frozen tissue were included. The Quantitative Multiplex PCR of Short Fluorescent Fragments (QMPSF) method was used for molecular screening (1). The QMPSF was based on the simultaneous amplification, from normal and tumoral tissues, of 8 selected target genomic sequences according to literature data: DCC (18q21); EGFR (7p12); TP53 (17p13.1); BLK (8p23-p22); MYC (8q24.12); APC (5q22.2); ERBB2 (17q12); STK6 (20q13.31); and two control: PCBD2 (5q31.1); HMBS (11q23.3). The primary end-point was to determine the association between molecular alterations and disease-free survival (DSF). Combinations of alterations were defined according to univariate results (p Results: A total of 401 patients were included with a median follow-up of 48 months. There were 236 stage II and 165 stage III and the recurrence rate was 30.2%. Loss of DCC/18q, TP53/17p, BLK/8p, and APC/5q were detected in respectively 33.2%, 26.7%, 22.7%, 9.7% and gain of EGFR/7p, MYC/8q, ERBB2/17q and STK6/20q were observed in 31.7%, 35.7%, 18.7% and 48.9% of cases, respectively. There was no significant interaction between alterations and disease stage. DFS was significantly associated with loss of DCC/18q (57.5 vs 70.6%, p = 0.02) with a trend for BLK/8p loss (59.8 vs 68.6%, p = 0.08) and ERBB2/17q gain (59.2 vs 68.5%, p = 0.14). In multivariate analysis, the combination of loss DCC/18q and/or loss BLK/8p and/or gain ERBB2/17q was significantly associated with DFS. The DFS significantly decreased from 74.2% to 61.7% (HR = 1.78, 95CI: 1.14-2.77) and to 57.2% (HR =2.06, 95CI: 1.26-3.37) in patients with respectively none, 1 and at least 2 of these 3 alterations. Conclusions: Combination of DCC/18q, BLK/8p and ERBB2/17q gene copy number alterations is associated with disease-free survival in stage II-III colon cancer. Disclosure: All authors have declared no conflicts of interest.