Systemic therapy with or without local intervention for oligometastatic oesophageal squamous cell carcinoma (ESO-Shanghai 13): an open-label, randomised, phase 2 trial.

Background: The efficacy of local therapy for patients with oligometastatic oesophageal squamous cell carcinoma is unclear. We aimed to assess the efficacy of local plus systemic therapy compared with systemic therapy alone in patients with oligometastatic oesophageal squamous cell carcinoma.

Methods: The ESO-Shanghai 13 trial was a randomised, open-label, multicentre, phase 2 trial. Patients (aged ≥18 years) were recruited from six hospitals in China with histological confirmation of oligometastatic oesophageal squamous cell carcinoma with a controlled primary tumour and one to four metastatic lesions. Eligible patients were randomly assigned via a computer-generated schedule in a 1:1 ratio to receive either systemic therapy alone (ie, systemic therapy only group) or combined systemic and local therapy (ie, systemic and local therapy group). The systemic therapy regimens in both groups were at the discretion of the investigator and included chemotherapy alone, anti-PD-1 antibodies alone, or chemotherapy plus anti-PD-1 antibodies. Local therapy-radiotherapy, surgery, or thermal ablation-was delivered to all metastatic lesions for patients in the systemic and local therapy group. Randomisation was balanced dynamically on three factors: the number of disease sites, the lines of systemic therapy, and the location of the metastases. Patients and investigators were not masked to treatment allocation. The primary endpoint was progression-free survival, defined as the time from randomisation to progression or death from any cause in the intention-to-treat population. The safety population included all patients who had undergone random assignment and at least one of the intended therapies. This trial is registered with ClinicalTrials.gov, NCT03904927. The trial is ongoing but closed to new participants.

Findings: 116 patients were screened for enrolment between March 5, 2019, and Sept 16, 2021, and 104 patients who met the eligibility criteria were randomly assigned to the systemic and local therapy group (n=53) or the systemic therapy only group (n=51). 20 (38%) patients in the systemic plus local therapy group and 23 (45%) patients in the systemic therapy only group received anti-PD-1 antibody-based systemic therapy; three patients in the systemic and local therapy group did not receive systemic therapy. At a median follow-up of 30·5 months (IQR 24·7-37·8), median progression-free survival was 15·3 months (95% CI 10·1-20·5) in the systemic and local therapy group versus 6·4 months (5·2-7·6) in the systemic therapy only group (stratified hazard ratio 0·26 [95% CI 0·16-0·42]; stratified log rank p<0·0001). Grade 1-2 acute oesophagitis was more common in the systemic and local therapy group than in the systemic therapy only group (10 [19%] vs one [2%] patients; p=0·036). The number of patients who had grade 3 or worse treatment-related adverse events was similar between groups (25 [47%] vs 21 [41%]; p=0·538), with the most common adverse events being leukocytopenia (17 [32%] vs 18 [35%]) and neutropenia (19 [36%] vs 20 [39%]). Treatment-related deaths occurred in two patients in the systemic and local therapy group and one patient in the systemic therapy only group.

Interpretation: The addition of local treatment for metastases could significantly improve progression-free survival among patients with oligometastatic oesophageal squamous cell carcinoma being treated with systemic therapy. Our findings suggest that combining local and systemic therapy could be a treatment option for patients with oligometastatic oesophageal squamous cell carcinoma, but further support from phase 3 trials is required.

Funding: Science and Technology Commission of Shanghai Municipality, National Nature Science Foundation of China, and Shanghai Municipal Health Commission.

Translation: For the Chinese translation of the abstract see Supplementary Materials section.