3432 - Durable Local Control of Adding Palliative Radiotherapy to Nivolumab for Advanced Esophageal Cancer
Presenter(s)
T. Fujisawa1, H. Hirata1, D. Kotani2, H. Hojo1, M. Nakamura1, S. I. Kageyama1,3, H. Oyoshi1, K. Tomizawa1, S. Mishima2, T. Kojima2, Y. Zhou1, K. Fukushi1, K. Makita1, Y. Koike1, G. Uchida1, H. Sakurai4, and S. Zenda1; 1Department of Radiation Oncology, National Cancer Center Hospital East, Kashiwa, Japan, 2Department of Gastroenterology, National Cancer Center Hospital East, Kashiwa, Japan, 3Division of Radiation Oncology and Particle Therapy, Exploratory Oncology Research and Clinical Trial Center, National Cancer Center, Chiba, Japan, 4Department of Radiation Oncology, Faculty of Medicine, University of Tsukuba, Tsukuba, Japan
Purpose/Objective(s): Nivolumab (anti-PD-1 monoclonal antibody therapy) has recently become established as one of the standards of care for patients with advanced esophageal carcinoma (EC) who are ineligible for definitive treatment, including those with recurrent or metastatic disease. Although nivolumab is expected to have a systemic effect, it alone is insufficient to relieve local symptoms. Palliative radiotherapy (RT) is widely used to improve such symptoms and suppress local disease progression in patients with advanced EC. Palliative RT is sometimes added during nivolumab administration; however, the local efficacy and safety of adding palliative RT to nivolumab remain unclear. Thus, the aim of this retrospective study was to clarify the local efficacy and safety of palliative RT during the administration of nivolumab.
Materials/Methods: We retrospectively evaluated 34 consecutive patients with advanced EC who received palliative RT within 1 month of nivolumab administration at our institution between January 2018 and April 2023. We evaluated local progression-free survival (LPFS), local tumor response in irradiated lesions in accordance with RECIST 1.1, overall survival (OS), and treatment-related adverse events graded according to CTCAE 5.0. We immunohistochemically evaluated PD-L1 expression using the 28-8 antibody in tumor tissue samples obtained before palliative RT
Results: Among the 34 patients, 1 (3%), 24 (71%), and 9 (26%) had the Union for International Cancer Control 8th stage IVA, IVB, and recurrent disease, respectively, at the start of palliative RT. Thirty-three patients (97%) had squamous cell carcinoma, and one (3%) had adenosquamous carcinoma. The median RT dose was 20 Gy in five fractions, ranging from 8 to 40 Gy in 1–20 fractions (2–8 Gy/fraction). RT was delivered to the primary tumors and lymph node metastases in 7 patients (21%), primary tumors in 15 patients (44%), lymph nodes in 10 patients (29%), and distant metastasis in 2 patients (6%). With a median follow-up time of 23 months, the median LPFS was 7.8 months (95% CI: 6.1–not reached). There was no significant difference in LPFS according to the tumor proportion score (TPS; =1% vs <1%) status (hazard ratio = 0.7 [95% CI: 0.3–1.8]). The best response rate for irradiated lesions was 56% (19 of 34 patients), with 35% complete and 21% partial responses. No patients showed progressive disease at the best-response evaluation. The median OS was 13 months (95% CI: 7.4– not reached). RT-related grade-3 esophageal stenosis was observed in one patient (3%). Grade 3 or higher immune-related adverse events (irAEs) were recorded in six patients (17%). One patient developed a Grade 5 irAE (myocarditis) outside the irradiated field.
Conclusion: After the addition of palliative RT during nivolumab administration, > 50% of patients achieved at least 6 months of LPFS without severe RT-related toxicities, regardless of the TPS.