4046 Background: Perioperative chemotherapy improves cure rate in locally advanced gastroesophageal adenocarcinoma (GEA), and immune checkpoint inhibitors are active at the metastatic stage. This trial tests the hypothesis that the addition of avelumab to perioperative chemotherapy will increase the major pathologic response (MPR) rate in comparison with historical controls. Methods: Phase II study of avelumab + chemotherapy (docetaxel, cisplatin and 5-FU or mDCF) given every 2 weeks for 4 cycles before and after surgery. Main inclusion criteria: GEA, cT3 and/or cN+, M0, WHO PS 0-1. Main exclusion criteria: use of immunosuppressants, serious autoimmune disease, daily intake >10 mg prednisone. Staging studies: CT, PET-CT, endoscopic ultrasound, diagnostic laparoscopy. Surgical resection: D2 lymphadenectomy, en-bloc esophagectomy for type I/II gastroesophageal junction (GEJ) tumors. Aim of the study: MPR as defined as tumor regression grades 0-1 (modified Ryan scheme); as per hypothesis, this experimental regimen will result in a 20% rate of MPR, compared with 7% with chemotherapy alone. Simon 2-stage design: if less than 2 MPR are seen in the first 16 patients, the study will be closed. The study hypothesis cannot be rejected if at least 6 MPR are seen in the first 50 patients. All adverse effects are prospectively recorded per CTCAE guidelines in patients who have received at least one treatment cycle. Survival rates are calculated with Kaplan-Meier method. Preliminary results are presented since the study has met its primary endpoint. Results: Feb 2018-Feb 2020: 28 patients enrolled (25 M/3 F, age 45-78). Location: GEJ (23), stomach (5). Staging: cT3 (25), cT4 (1), cN+ (20). Biomarkers expression: mismatch repair (MMR) protein loss (3/28); PD-L1(clone 73-10) expression in 1% (TPS) or more of tumor cells seen in 12/28 samples, and >10% in 6 patients. Grade 3 toxicity: stomatitis (2/28); nausea (2/28); vomiting (1/28); diarrhea (1/28); hypothyroidism (1/28); arthralgia (3/28); neutropenia (1/28). Grade 4 toxicity: pneumonia (1/28); neutropenia (2/28). Postoperative 30-day mortality: 0%. One patient was excluded from efficacy analyses for M1 staging; 27 patients underwent surgery, 26 with R0 (96%). Six cases (22%) show MPR: 3 grade 0 (11%) and 3 grade 1 (11%) tumor regressions. No correlation was seen between MMR proteins or PD-L1 expression and tumor regression. With a median follow-up of 1.5 years (range 0.4-2.5), the disease-free survival rate is projected to be 0.92 (95% CI 0.83-1.00) at 12 months and 0.77 (95% CI 0.58-1.00) at 24 months. Conclusions: The combination of mDCF chemotherapy with Avelumab demonstrates a promising safety and activity profile. Ongoing laboratory investigations are underway to correlate our findings with tumor molecular features before exposure to treatment. Clinical trial information: NCT03288350.
Background: It has recently been reported that mismatch repair (MMR) status and microsatellite instability (MSI) status in gastroesophageal carcinomas predict surgical, chemotherapeutic and immunotherapeutic outcomes; however, there is extensive variability in the reported incidence and clinical implications of MMR/MSI status in gastroesophaegal adenocarcinomas. We characterized a Canadian surgical patient cohort with respect to MMR status, clinicopathologic correlates and anatomic tumour location. Methods: We investigated MMR and BRAF V600E status of gastroesophaegal adenocarcinomas in patients who underwent gastrectomy or esophagectomy with extended (D2) lymphadenectomy at a single centre between 2011 and 2019. We correlated patterns of MMR expression in the overall cohort and in anatomic location–defined subgroups with treatment response and overall survival using multivariate analysis. Results: In all, 226 cases of gastroesophaegal adenocarcinoma (63 esophageal, 98 gastroesophageal junctional and 65 gastric) were included. The MMR-deficient (dMMR) immunophenotype was found in 28 tumours (12.3%) (15 junctional [15.3%], 13 gastric [20.0%] and none of the esophageal). The majority (25 [89%]) of dMMR cases showed MLH1/PMS2 loss without concurrent BRAF V600E mutation. Two MSH2/ MSH6-deficient gastric tumours and 1 MSH6-deficient junctional tumour were detected. The pathologic response to preoperative chemotherapy was comparable in the dMMR and MMR-proficient (pMMR) cohorts. However, dMMR status was associated with significantly longer median overall survival than pMMR status (5.8 yr v. 2.4 yr, hazard ratio [HR] 1.91, 95% confidence interval [CI] 1.06–3.46), particularly in junctional tumours (4.6 yr v. 1.9 yr, HR 2.97, 95% CI 1.27–6.94). Conclusion: Our study shows that MMR status has at least prognostic value, which supports the need for biomarker testing in gastroesophageal adenocarcinomas, including junctional adenocarcinomas. This highlights the clinical significance of determining the MMR status in all adenocarcinomas of the upper gastrointestinal tract. Response to induction chemotherapy, however, was not influenced by MMR status.
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