Definitive Proton Radiotherapy Combined With Chemotherapy and Immunotherapy for Locally Advanced Esophageal Squamous Cell Carcinoma: A Phase I Clinical Study
Trial Snapshot
- Phase
- Phase 1
- Status
- Not yet recruiting
- Sponsor
- Enrollment
- 23
- Locations
- 1
- Primary Endpoint
- Toxicity
Study Overview
Brief Summary
The standard treatment for locally advanced esophageal squamous cell carcinoma (ESCC) is definitive concurrent chemoradiotherapy (CCRT). However, conventional photon-based radiotherapy is associated with excessive radiation exposure to normal tissues and a high incidence of treatment-related toxicities. Proton radiotherapy, one of the major advances in radiation oncology in recent years, offers the dosimetric advantage of reduced radiation to surrounding normal tissues, thereby decreasing the rate of adverse events. Two recent clinical studies have suggested that, compared with conventional photon radiotherapy, proton radiotherapy can significantly reduce the incidence of treatment-related toxicities and potentially improve patient survival outcomes.
Immune checkpoint inhibitors (ICIs) have been widely used in both locally advanced and advanced esophageal cancer and have demonstrated promising clinical efficacy. Preliminary results from several ongoing phase III clinical trials indicate that combining ICIs with concurrent chemoradiotherapy is both safe and effective. Moreover, proton radiotherapy, by minimizing the low-dose radiation exposure to circulating peripheral lymphocytes, may better preserve systemic immune function. Therefore, compared to photon therapy, proton radiotherapy may theoretically enhance the synergistic effect when combined with ICIs, offering a potential survival benefit.
Based on this rationale, we propose a phase I clinical trial to investigate the safety and preliminary efficacy of definitive proton chemoradiotherapy combined with immune checkpoint inhibition in patients with locally advanced esophageal squamous cell carcinoma.
Detailed Description
- Background Esophageal squamous cell carcinoma (ESCC) is a highly prevalent malignancy in China, ranking sixth in incidence and fourth in cancer-related mortality, posing a serious threat to public health. Over 50% of newly diagnosed patients present with locally advanced esophageal squamous cell carcinoma. The RTOG 8501 and RTOG 9405 trials established definitive concurrent chemoradiotherapy (CCRT) as the standard of care for inoperable locally advanced esophageal squamous cell carcinoma, yielding a 5-year overall survival (OS) rate of approximately 30%. However, despite optimization of physical radiation dose and fractionation in photon radiotherapy and modifications in chemotherapy regimens, further improvements in clinical outcomes have been limited.
Recent research has focused on two primary strategies to enhance the efficacy of definitive CCRT in locally advanced esophageal squamous cell carcinoma: the incorporation of proton radiotherapy, and the integration of immune checkpoint inhibitors (ICIs).
Conventional photon therapy using 6-8 MV X-rays typically involves a total dose of 50-60 Gy delivered over 28-30 fractions, with or without elective nodal irradiation (ENI). However, photon radiotherapy is limited by large gross tumor volumes (GTV) and widespread lymphatic involvement, leading to excessive radiation exposure to organs-at-risk (OARs). Elevated doses to the heart and lungs increase the risk of late toxicities such as radiation-induced heart disease and pulmonary fibrosis, thereby impairing cardiopulmonary function and survival. Additionally, high-dose exposure to circulating lymphocytes and the thoracic vertebrae compromises systemic immunity by inducing lymphopenia, adversely affecting prognosis.
Proton radiotherapy, with its Bragg peak effect, delivers maximal radiation dose at the end of its range, significantly sparing surrounding normal tissues. Biologically, this translates into a lower incidence of late toxicities in the heart and lungs and reduced lymphocyte depletion, potentially leading to improved clinical outcomes. Emerging clinical data suggest that compared to conventional photon therapy, PRT reduces treatment-related toxicities and may improve survival.
ICIs have shown promising efficacy in advanced EC and are increasingly being investigated in earlier disease stages. Several phase III trials (ESCORT-CRT, Keynote 975, RATIONAL 311, etc.) are evaluating the combination of CCRT with ICIs in locally advanced esophageal squamous cell carcinoma, and preliminary data indicate that this approach is both safe and effective. Since proton radiotherapy minimizes radiation dose to circulating lymphocytes, it may exhibit superior synergy with immunotherapy compared to photon radiotherapy, potentially offering enhanced therapeutic benefit.
Study Design
- Study Type
- Interventional
- Allocation
- Non Randomized
- Intervention Model
- Single Group
- Primary Purpose
- Treatment
- Masking
- None
Eligibility Criteria
- Ages
- 18 Years to 75 Years (Adult, Older Adult)
- Sex
- All
- Accepts Healthy Volunteers
- No
Inclusion Criteria
- •Age 18-75 years ECOG performance status 0-1 Histologically confirmed esophageal squamous cell carcinoma (ESCC) Stage II-IVA disease (AJCC 8th edition), confirmed via contrast-enhanced CT of the neck, chest, and abdomen, or PET-CT Unresectable by surgical evaluation or patient refusal of surgery No prior oncologic treatment Life expectancy >6 months Radiotherapy plan meets physical dose constraints Signed informed consent by patient or legal representative
Exclusion Criteria
- •Age <18 or >75 years ECOG >1 or inability to tolerate treatment Histology other than squamous cell carcinoma Stage I or IVB disease High risk of hemorrhage or fistula, as assessed by imaging and radiation oncologists Previously treated patients Life expectancy <6 months Contraindications to chemotherapy or immunotherapy Radiotherapy plan fails to meet dose constraints Lack of signed informed consent
Arms & Interventions
Pronton radiotherapy with chemoimmunotherapy
Pronton radiotherapy with chemoimmunotherapy
Intervention: Proton radiotherapy (Radiation)
Pronton radiotherapy with chemoimmunotherapy
Pronton radiotherapy with chemoimmunotherapy
Intervention: Immune Checkpoint Inhibitors (Drug)
Outcomes
Primary Outcomes
Toxicity
Time Frame: One year
The incidence of myelosuppression, radiation-induced pneumonitis and esophagitis, radiation-induecd cardiac injury, etc.
Secondary Outcomes
No secondary outcomes reported