The safety and short-term efficacy of selective internal radiation therapy combined with systemic treatment for unresectable malignant hepatic tumors in Chinese patients.

e16247 Background: There are many systemic treatment options for patients with unresectable malignant hepatic tumors. In China, selective internal radiation therapy (SIRT) with yttrium-90 (Y90) resin microspheres was approved until 2022. The aim of this retrospective study was to investigate the safety and short-term efficacy of SIRT with Y90 resin microspheres followed by systemic treatment in Chinese patients. Methods: The study analyzed patients who received SIRT with Y90 combined with systemic treatment at our center between June 2022 and October 2023. The study's primary endpoint was to determine the objective response rate (ORR), while safety was the secondary endpoint. Response was measured based on modified Response Evaluation Criteria in Solid Tumors criteria (mRECIST) up to 90 days after the initial therapy. Safety was evaluated using the Common Terminology Criteria for Adverse Events Version 5.0. Results: 21 patients wereincluded, of whom 22 times of SIRT were performed. 18 patients had HCC, and 3 had mCRC.The baseline characteristics of the patients are shown in Table. The median age was 54 years (IQR, 48-59 years) and 90.5% of patients were male. According to Eastern Cooperative Oncology Group performance status, grade 0 and grade 1 were 81% and 19%, respectively, whereas Child-Pugh A represented 90.5% of cases. The proportion of patients with hepatitis B virus infection was 95.2%. Thirteen (61.9%) patients received different treatments before SIRT. The median number of tumors was 2.5 (IQR, 1-4.3), whereas the median diameter of the largest lesion was 100.4 mm (IQR, 68.3-127.7 mm). PVTT was classified as follows: Vp1 (n = 3), Vp2 (n = 2), Vp3 (n = 2) and Vp4 (n = 1). Median AFP was 33.2 ng/mL (IQR, 5.9-401 ng/mL). The median total radiation activity administered was 1.4 GBq (IQR, 0.9-2.7 GBq) and the median target tissue dose was 205 Gy (IQR, 155-242 Gy). Nine (43%) patients were downstaged to surgery. Four (19%) patients had a complete response, fifteen (71.4%) had a partial response and two (9.5%) had a progressive disease. ORR and disease control rate were 90.5% and 90.5%, respectively. None of the patients experienced grade 3 and higher adverse events. The most common treatment-related adverse events were fever and abdominal pain, which required no special treatment. Conclusions: SIRT with Y90 resin microspheres combined with systemic treatment is safe and effective in patients with unresectable malignant hepatic tumors, which resulted in encouraging ORR (90.5%) and a downstaging rate (43%). Clinical trial information: ChiCTR2300077524. Table: see text