Improving Outcome of Patients With Squamous Cell ESophageal CArcinoma by Dose escaLATion Using High-prEcision Mr-guided Radiotherapy (ESCALATE): a Phase 1 Dose Finding Trial
Objective: The main objective of this study is to determine the maximum tolerated dose (MTD) of 2-fraction boost MRI-guided radiotherapy (MRgRT) for patients with SCC following CROSS therapy. The secondary objectives are feasibility, non-dose limiting toxicity, oncological outcomes and to explore variables for early response evaluation. Study design: 6+3 dose-escalation design with 3 radiotherapy dose levels. Study population: Patients with a resectable squamous cell esophageal carcinoma who are eligible for nCRT, surgery and MRgRT. Intervention: 2 sequential, homogenous boost fractions of 4-7 Gy on the gross tumor volume (GTV) in the week following CROSS using MR-guided online adaptive radiotherapy on the MR-linac. Start in dose level 0, of 2 x 5Gy boost per patient, and if safe this is increased step-wise to a maximum dose level 2 of 2 x 7Gy per patient. Main study parameters/endpoints: The primary endpoint is the incidence of a dose limiting toxicity (DLT). Early DLT is defined as radiation induced esophageal fistula/ perforation/ hemorrhage/ necrosis or tracheal, bronchial or bronchopleural fistula/tracheal or bronchopulmonary hemorrhage grade ≥ 3 or any non-hematological grade 4 toxicity according to Common Toxicity Criteria for Adverse Events (CTCAE) version 5.0 occurring within 14 weeks after the start of radiotherapy and before surgery or the postponing of surgery \> 14 weeks after the end of radiotherapy due to any grade of treatment-related toxicity. Subacute DLT is defined as peri- and/or postoperative complications occurring within 30 days after surgery, defined as postoperative anastomotic leakage or pneumonitis ≥ 3b according to Clavien-Dindo. Secondary endpoints are non-DLT toxicity, the technical feasibility of dose delivery, perioperative complications, and oncological outcomes including R0 resection rate, histopathological tumor response, local and regional recurrence and death from any cause. Nature and extent of the burden and risks associated with participation, benefit and group relatedness: The benefits for the patients may include higher probability of complete pathological response that initially leads to increased survival and could eventually result in organ-sparing treatment programs. Compared to standard treatment, the CROSS regimen including the sequential boost will take 2 days extra in the final week of CROSS. Possible risks include higher radiation toxicity and surgical complication rates. However, it is expected this increase to be minor, for the investigators will use dose constraints on organs at risk, which are associated with low radiation-induced toxicity, and they will not be exceeded.
⁃ In order to be eligible for this study, a subject must meet all of the following criteria:
• Histologically confirmed squamous cell carcinoma of the esophagus or GE- junction (Siewert I/II)
• Potentially resectable, locally advanced esophageal tumor (cT1bN+, cT2-3, N0-3, M0) based on standard primary staging by EUS and 18F-FDG PET-CT
• Scheduled to receive neoadjuvant chemoradiotherapy according to CROSS-regimen: weekly administration of carboplatin and paclitaxel for 5 weeks and concurrent radiotherapy (41.4Gy in 23 fractions, 5 days per week), followed by esophagectomy (as judged by the multidisciplinary tumor board)
• Tumor length ≤ 10 cm
• Age ≥ 18 years
• WHO performance status 0-2
• Signed informed consent
• Tumor volume that can be defined on MRI at baseline (T2w and DW-MRI)
• Absence of any psychological, familial, sociological or geographical condition potentially hampering compliance with the study protocol and follow-up schedule before patient registration/randomization, written informed consent must be given according to ICH/GCP, and national/local regulations.