Background <p>We aimed to determine the maximum tolerable dose (MTD) and dose-limiting toxicities (DLTs) of weekly lobaplatin chemotherapy concurrent with external beam radiotherapy (EBRT) using image-guided volumetric-modulated arc therapy (VMAT) and brachytherapy in locally advanced cervical cancer (LACC).</p> Methods <p>Patients with clinical stage IB3-IVA cervical cancer were enrolled following a standard 3 + 3 dose escalation design. Patients received EBRT with 45&#xa0;Gy in 25 fractions to the pelvis and 60&#xa0;Gy in 25 fractions to the involved lymph nodes. Then high-dose-rate intracavitary brachytherapy was conducted with 28&#xa0;Gy in 4 fractions. The starting dose of weekly lobaplatin was 8&#xa0;mg/m², then increased by 2 mg/m² for a total of 5 levels. The primary endpoints were the MTD and DLTs of weekly lobaplatin. DLTs were defined as follows: 1) grade 4 neutropenia, or thrombocytopenia of grade 3 or higher; 2) grade 3 or higher nonhematologic toxicity; and 3) failure to complete 3 cycles of lobaplatin due to treatment-related toxicity.</p> Results <p>Between December 2020 and October 2022, 21 patients were enrolled. Three patients experienced DLTs: grade 3 fatigue at 14 mg/m², receiving two cycles of chemotherapy at 16 mg/m², and grade 3 fatigue at 16 mg/m². The only severe and dose-limiting nonhematologic toxicity was grade 3 fatigue. The MTD of weekly lobaplatin was 14 mg/m².</p> Conclusions <p>The MTD of weekly lobaplatin concurrent with VMAT and brachytherapy for LACC was established as 14 mg/m². A weekly dose of 12 mg/m² of lobaplatin is recommended in combination with radiotherapy in patients with LACC.</p> Trial registration <p>This study is registered with chictr.org, ChiCTR2000040113 on 21 November 2020&#xa0;prior to participant enrollment, and is now complete.</p>