The Keystone-001 study was designed to prospectively evaluate the efficacy and safety of preoperative treatment with pembrolizumab plus paclitaxel and cisplatin followed by Da Vinci robotic radical surgery in patients with locally advanced (stage III) ESCC. The study also explored the potential mechanism of this treatment strategy (NCT 04389177, 5/15/2020). The full study methods for this prospective, single-arm, single-center, open-label, phase-II study have been published previously. For further investigating the immune cell subpopulations that determine the efficacy, we performed single-cell sequencing on peripheral blood and tumor tissues after neoadjuvant therapy, and validated using flow cytometry. Of the 49 patients enrolled between July 8, 2020, and February 10, 2022, 47 received neoadjuvant therapy and were included in the ITT analysis. Among all patients who received neoadjuvant therapy, no grade ≥3 AEs were reported. Improvements from baseline nutritional status were observed with increases in patients’ median body weight and NRI. QoL evaluations showed improvements from baseline to post-adjuvant therapy in all functional scales and symptom scales of EORTC QLQ-C30 and in all items of the EORTC QLQ-OES18 questionnaire. Among all 45 patients in the efficacy analysis, the MPR rate was 73.3%, the pCR rate was 42.2%, the ORR was 95.6%, and the DCR was 100%. After a median follow-up of 23.3 months (95% CI 20.6, 24.9; maximum follow-up 34 months), the 1- and 2-year OS and DFS rates were 95.6 and 90.5% and 95.6 and 86.3%, respectively. The single-cell sequencing results showed that the main cell populations that affect the response of this treatment strategy were NKT and NK cell subpopulations in peripheral blood. Further analysis results showed that the TRGC2+NKT and FGFBP2+NK cell subpopulation in peripheral blood were more significantly increased in peripheral blood from patients with a good response. The preliminary findings of this trial were safe and effective, and further phase III studies (Keystone-002) have begun to recruit participants.

Background: Esophageal squamous cell carcinoma (ESCC) is one of the most refractory malignant tumors. Esophageal cancer (EC) is a malignant tumor with a high incidence worldwide, and over 50% of EC cases occur in China. Under the National Comprehensive Cancer Network (NCCN) guidelines, concurrent chemoradiotherapy is the only standard neoadjuvant treatment for locally advanced ESCC. In the first-line treatment of advanced ESCC, the efficacy of immune checkpoint inhibitors (ICIs) combined with systemic chemotherapy is significantly better than that of chemotherapy alone. Paclitaxel and cisplatin (TP), as one of the neoadjuvant chemotherapy regimens for locally advanced ESCC, have been widely used in China in recent years. ICIs combined with TP as neoadjuvant therapy seems promising. Methods: This is an open-label, single-arm, single-center, phase-II trial. Locally advanced resectable (stage III) ESCC patients who have not undergone previous systemic treatments will be enrolled in this study. All the subjects will intravenously receive 3 cycles of pembrolizumab (200 mg) on day 1, paclitaxel (135 mg/m(2)) on day 2, and cisplatin (20 mg/m(2)) on days 2-4, every 3 weeks. After an efficacy evaluation, the subjects will undergo Da Vinci robot-assisted radical resection. If the postoperative pathologic results do not reveal a complete response, pembrolizumab will be administrated for at least 6 cycles as an adjuvant therapy with the same usage as before. The primary endpoints are the major pathological response and safety. The secondary endpoints include the objective response rate (ORR), overall survival (OS), disease-free survival (DFS), the R0 resection rate, and perioperative complications. The exploratory endpoint is to examine the correlation between related biomarkers and tumor responses to this neoadjuvant treatment regimen. Discussion: This trial is the first enrolled study to evaluate the safety and efficacy of pembrolizumab combined with TP as neoadjuvant therapy for locally advanced ESCC. Currently, under the NCCN guidelines, neoadjuvant chemoradiotherapy (nCRT) is the only recommended treatment for locally advanced ESCC. This phase-II study will provide preliminary evidence of the efficacy of pembrolizumab combined with TP as novel neoadjuvant therapy for patients with locally advanced ESCC.

BackgroundNeoadjuvant concurrent chemoradiotherapy with surgery is the standard treatment for esophageal squamous cell carcinoma (ESCC) in NCCN guidelines. But many patients refused or abandon radiotherapy because of the intolerable adverse effects. We designed a single-arm, open-label, phase II trial of pembrolizumab plus paclitaxel, cisplatin followed by Da Vinci robot surgery for locally advanced (stage III) ESCC. The purpose is to observe and evaluate the efficacy and safety.MethodsThe enrolled subjects are the locally advanced and resectable (stage Ⅲ,8th, AJCC) ESCC patients, who will receive pembrolizumab (200mg, IV, D1, Q3W for 3 cycles), paclitaxel (135mg/m2, IV, D2, Q3W for 3 cycles) ,and cisplatin (20mg/m2, IV, D2-4, Q3W for 3 cycles), then will undergo Da Vinci robot-assisted McKeown surgery within 4-6 weeks after neoadjuvant treatment. If the pathology result is not a complete response, pembrolizumab alone as adjuvant therapy should be continued for at least 6 cycles with the same usage as before. Primary endpoints: major pathological response (MPR) rate; the safety. Secondary endpoints: pathological complete response (pCR) rate, objective response rate (ORR); 1, 3, 5-years OS and DFS, R0 resection rate and 30-day perioperative complications. Quality of life (EORTC QLQ-C30, OES18) and nutrition assessment (PG-SGA score).ResultsThis trial has recruited 42 subjects (50 in plan), of which 29 have finished robot surgery. The results confirm that this new treatment is safe (no adverse events of grade 3 or higher), and did not cause a delay in surgery. Patients' nutritional status and QOL improved significantly. R0 resection rate is 100%, with MPR 21/29 (72.4%), pCR 12/29 (41.4%), and ORR 28/29 (96.6%). No perioperative death has occurred so far.ConclusionPembrolizumab combined with paclitaxel and cisplatin as a neoadjuvant therapy was associated with few side effects, did not delay surgery, and induced a major pathological response in 72.4% of resected ESCC tumors. It may be better than the neoadjuvant concurrent chemoradiation recommended by NCCN guidelines.Clinical trial identificationNCT 04389177, date of registration: 15 May 2020.DisclosureAll authors have declared no conflicts of interest. BackgroundNeoadjuvant concurrent chemoradiotherapy with surgery is the standard treatment for esophageal squamous cell carcinoma (ESCC) in NCCN guidelines. But many patients refused or abandon radiotherapy because of the intolerable adverse effects. We designed a single-arm, open-label, phase II trial of pembrolizumab plus paclitaxel, cisplatin followed by Da Vinci robot surgery for locally advanced (stage III) ESCC. The purpose is to observe and evaluate the efficacy and safety. Neoadjuvant concurrent chemoradiotherapy with surgery is the standard treatment for esophageal squamous cell carcinoma (ESCC) in NCCN guidelines. But many patients refused or abandon radiotherapy because of the intolerable adverse effects. We designed a single-arm, open-label, phase II trial of pembrolizumab plus paclitaxel, cisplatin followed by Da Vinci robot surgery for locally advanced (stage III) ESCC. The purpose is to observe and evaluate the efficacy and safety. MethodsThe enrolled subjects are the locally advanced and resectable (stage Ⅲ,8th, AJCC) ESCC patients, who will receive pembrolizumab (200mg, IV, D1, Q3W for 3 cycles), paclitaxel (135mg/m2, IV, D2, Q3W for 3 cycles) ,and cisplatin (20mg/m2, IV, D2-4, Q3W for 3 cycles), then will undergo Da Vinci robot-assisted McKeown surgery within 4-6 weeks after neoadjuvant treatment. If the pathology result is not a complete response, pembrolizumab alone as adjuvant therapy should be continued for at least 6 cycles with the same usage as before. Primary endpoints: major pathological response (MPR) rate; the safety. Secondary endpoints: pathological complete response (pCR) rate, objective response rate (ORR); 1, 3, 5-years OS and DFS, R0 resection rate and 30-day perioperative complications. Quality of life (EORTC QLQ-C30, OES18) and nutrition assessment (PG-SGA score). The enrolled subjects are the locally advanced and resectable (stage Ⅲ,8th, AJCC) ESCC patients, who will receive pembrolizumab (200mg, IV, D1, Q3W for 3 cycles), paclitaxel (135mg/m2, IV, D2, Q3W for 3 cycles) ,and cisplatin (20mg/m2, IV, D2-4, Q3W for 3 cycles), then will undergo Da Vinci robot-assisted McKeown surgery within 4-6 weeks after neoadjuvant treatment. If the pathology result is not a complete response, pembrolizumab alone as adjuvant therapy should be continued for at least 6 cycles with the same usage as before. Primary endpoints: major pathological response (MPR) rate; the safety. Secondary endpoints: pathological complete response (pCR) rate, objective response rate (ORR); 1, 3, 5-years OS and DFS, R0 resection rate and 30-day perioperative complications. Quality of life (EORTC QLQ-C30, OES18) and nutrition assessment (PG-SGA score). ResultsThis trial has recruited 42 subjects (50 in plan), of which 29 have finished robot surgery. The results confirm that this new treatment is safe (no adverse events of grade 3 or higher), and did not cause a delay in surgery. Patients' nutritional status and QOL improved significantly. R0 resection rate is 100%, with MPR 21/29 (72.4%), pCR 12/29 (41.4%), and ORR 28/29 (96.6%). No perioperative death has occurred so far. This trial has recruited 42 subjects (50 in plan), of which 29 have finished robot surgery. The results confirm that this new treatment is safe (no adverse events of grade 3 or higher), and did not cause a delay in surgery. Patients' nutritional status and QOL improved significantly. R0 resection rate is 100%, with MPR 21/29 (72.4%), pCR 12/29 (41.4%), and ORR 28/29 (96.6%). No perioperative death has occurred so far. ConclusionPembrolizumab combined with paclitaxel and cisplatin as a neoadjuvant therapy was associated with few side effects, did not delay surgery, and induced a major pathological response in 72.4% of resected ESCC tumors. It may be better than the neoadjuvant concurrent chemoradiation recommended by NCCN guidelines. Pembrolizumab combined with paclitaxel and cisplatin as a neoadjuvant therapy was associated with few side effects, did not delay surgery, and induced a major pathological response in 72.4% of resected ESCC tumors. It may be better than the neoadjuvant concurrent chemoradiation recommended by NCCN guidelines.