A single-arm, multicenter, phase II study of utidelone in advanced solid tumors: Efficacy data from screening and the expansion cohort assessing utidelone plus sintilimab and oxaliplatin for advanced gastric cancer.

e16055 Background: Treatment regimens for many advanced solid tumors are limited and alternative options are needed.Utidelone is approved for the treatment of advanced breast cancer in China. NCT04911907 is a single-arm, multicenter, phase II study to assess the efficacy and safety of utidelone in advanced cancer. Stage I of the trial, completed in October 2023, included patients (pts) with pretreated advanced solid tumors. Based on the stage I data, a stage II expansion cohort (USO-G) investigated utidelone plus sintilimab and oxaliplatin as first-line therapy for advanced gastric cancer (GC). Here, we report efficacy and safety data from stage I and stage II for interim analysis. Methods: Eligible pts aged 18–70 years with pretreated advanced solid tumors were enrolled in stage I and received utidelone monotherapy (35 mg/m 2 /day iv on days 1–5 every 21 days). In stage II, eligible pts with metastatic and/or unresectable HER2 negative GC received utidelone (30mg/m 2 /day iv on days 1–5 every 21 days) plus sintilimab (200 mg iv Q3W) and oxaliplatin (130 mg/m 2 /day Q3W for up to 6 cycles), until disease progression or unacceptable toxicity. Results: From March 18 th 2021 to October 13 th 2022, 79 pts were enrolled into 7 tumor cohorts and 54 pts were evaluable for efficacy. The best overall responses were 1 CR, 3 PRs and 3 SDs in 10 esophageal cancer pts, 3 PRs and 5 SDs in 15 GC pts, 1 PR and 3 SDs in 10 ovarian cancer pts, SD for all 4 cholangiocarcinoma pts, 3 SDs in 4 cervical cancer pts, 2 SDs in 3 pancreatic cancer pts and a PR in 1 neuroectodermal tumor patient. Grade 3/4 TRAEs occurred in 27.8% of pts in stage I, and included anemia (13.9%), peripheral neuropathy (11.4%) and neutropenia (7.6%). No treatment-related deaths occurred. Gastric cancer was chosen as the expansion cohort indication. As of February 1 st 2024, 14 eligible pts with GC with a median age of 57 years (range, 41–69) were enrolled. The median follow-up was 5.5 months (range, 1.0–9.7) and the longest duration of response was 8.0 months. A total of 8 PRs and 3 SDs were achieved in the 11 pts evaluable for efficacy, and 6 pts including the 3 with SD were still receiving treatment. Grade 3/4 TRAEs occurred in 28.6% of pts including diarrhea (14.3%), fatigue (14.3%), neutropenia (14.3%), and vomiting (7.1%). Other AEs were all Grade 1 or 2, with no treatment-related deaths. Conclusions: Utidelone monotherapy showed antitumor activity and manageable toxicity in pts with advanced solid tumors. Utidelone plus sintilimab and oxaliplatin demonstrated promising efficacy and an acceptable safety profile as first-line treatment for pts with GC. Stage II of the USO-G study is still actively enrolling; further data will be provided at the time of presentation. Clinical trial information: NCT04911907 .