Cetuximab in combination with chemoradiotherapy prior to surgery in patients with resectable, locally advanced esophageal carcinoma: A prospective, multicenter phase lb-ll trial of the Swiss Group for Clinical Cancer Research (SAKK 75/06)

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Background: Cetuximab significantly enhances efficacy of radiotherapy and chemotherapy in head and neck cancer. We investigated the safety and feasibility of adding cetuximab to neoadjuvant chemoradiation of locally advanced esophageal cancer. Methods: Pts with resectable, locally advanced squamous cell carcinoma (SCC) or adenocarcinoma (AC) of the thoracic esophagus or gastroesophageal junction (staged by EUS, CT and PET scan) were treated with 2 cycles of induction chemotherapy (docetaxel 75mg/m2, cisplatin 75mg/m2 q3w and weekly cetuximab 250mg/m2), followed by concomitant chemo- immuno-radiation therapy (CIRT: docetaxel 20mg/m2, cisplatin 25mg/m2 and cetuximab 250mg/m2 weekly five times concomitant with 45 Gy radiotherapy in 25 fractions); followed by surgery 4–8 weeks later. The phase I part consisted of 2 cohorts of 7 patients each, without and with docetaxel during CIRT, respectively. Interpatient dose-escalation (adding docetaxel during CIRT) was possible if < 2 out of 7 pts of the 1st cohort experienced limiting toxicity. Having finished the phase 1 part, 13 additional patients were treated with docetaxel-containing CIRT in a phase II part. Pathological response was evaluated according to the Mandard classification. Results: 27 pts from 12 institutions were included. As of today, results from 20 pts are available (cohort 1: 7, cohort 2: 7, phase ll : 6). Median age was 64yrs (range 47–71). 11 AC; 9 SCC. 19 pts (95%) completed CIRT (1 pt stopped treatment during induction therapy due to sepsis). 17 pts underwent resection (no surgery: 1pt for PD, 1pt for cardiac reasons). Grade 3 toxicities during CIRT included anorexia 15%, dysphagia/esophagitis 15%, fatigue 10%, nausea 10%, pruritus 5%, dehydration 5%, nail changes 5% and rash 5% .1 pt suffered from pulmonary embolism. 13 pts (65%, intention-to-treat) showed a complete or near complete pathological remission (cohort 1: 5, cohort 2: 4, phase II: 4). Conclusions: Adding cetuximab to preoperative chemoradiation for esophageal cancer is safe and feasible in a community-based multicenter setting. Antineoplastic activity is encouraging with 65% pathological responders.

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Response evaluation with endoscopic ultrasound (EUS) measuring maximum tumor thickness to predict pathological response after neoadjuvant chemoradiation therapy (CRT) in patients with locally advanced esophageal cancer (EC)

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Background: EUS does not accurately assess T-stage after neoadjuvant CRT due to inflammation, necrosis and fibrosis. We evaluated whether maximum tumor thickness (MTT) can predict pathological response (tumor regression grade, TRG) after CRT. Methods: Patients (pts) with resectable, locally advanced EC, were treated with 2 cycles of docetaxel/cisplatin (DC) q3w followed by CRT (DC weekly x5 with concomitant 45 Gy radiation therapy) and surgery. Radial scan EUS (7.5MHz) measured MTT at baseline and 3–5 weeks after CRT completion. We prospectively hypothesized that MTT =6mm in the second EUS predicts complete and subtotal pathological response (TRG1 and 2), tested by logistic regression. The effect of >50% reduction of MTT was analysed as well. Results: 66 pts from 11 institutions were treated; median age 61y (35–70y); adenocarcinoma (AC) 53%; squamous cell carcinoma 46%; 40 pts were eligible for the EUS project (10 no surgery, 10 tumor stenosis prohibiting EUS, 5 MTT not measured, 1 intolerant to EUS). Initial EUS staging: 9 uT2N1, 3 uT3N0, 27 uT3N1, 1 uT3Nx; Siewert-type-1 in 13 of 22 AC. Reduction of MTT to =6mm correctly predicted TRG1/2 with sensitivity (sens) 45%, specificity (spec) 90%, negative predictive value (NPV) 62%, and positive predictive value (PPV) 82%, the Iogistic regression model showed a trend predicting response only (OR 0.80; C.I. 0.62–1.03; p=0.082). Reduction of MTT >50% predicted TRG1/2 with sens 40%, spec 75%, NPV 56% and PPV 62%. Conclusions: The absolute value of maximum tumor thickness =6mm in the second EUS correctly predicts a good response to CRT in 82% (spec 90%) - rather than the relative reduction of MTT >50% -, but does not identify all responders. Feasibility in this multicenter setting was limited by exclusions due to tumor stenosis and incomplete measurements.

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No significant financial relationships to disclose.