AN0025 in combination with definitive chemoradiotherapy (dCRT) in unresectable locally advanced or locally recurrent esophageal cancer (EC): A single-arm, open-label, multicenter, phase Ib study.
Authors: Bi Nan , Liu Fang , Hu Ying , Wang Wei , Liu Wenyang , Liu Rongrui , Liu Yanli , Zhang Pei , Zhao Chuan Hua , Chen Jing , Luo Lingrong , Huang Zaijie , Gu Mengjie , Tang Kaiyang , Lu Xuyang , Song Xuyang , Zhao Tianyi , Wang Yuan , Liang Hongming , Xu Jianming 
Published: July 2024

e16076 Background: AN0025 is a selective EP4 inhibitor that demonstrates antitumor activity by modulating the accumulation and function of macrophages and immunosuppressive myeloid cells in tumor microenvironment. The combination of AN0025 with CRT as neoadjuvant therapy has shown synergistic antitumor efficacy in locally advanced rectal cancer in a prior clinical trial (NCT03152370). Methods: This Phase Ib study includes a dose escalation phase followed by an expansion phase to evaluate the safety, tolerability, and feasibility of AN0025 plus dCRT for unresectable locally advanced or locally recurrent EC or esophagogastric junction cancer. Antitumor efficacy was assessed per RECIST v1.1. The eligible patients (pts) are candidates for dCRT, who received RT (2.0 Gy/fraction, totally 50-60 Gy) with concurrent weekly paclitaxel and carboplatin for 4 weeks, followed by two doses of consolidation chemotherapy on Week 8 and Week 12. AN0025 (250 mg or 500 mg QD) was administered orally for 15 weeks concurrently with dCRT. At the beginning of Week 17, pts would start AN0025 monotherapy in the maintenance phase. Results: As of Jan 12, 2024, 12 pts (11 males and 1 female, median age 62) with histologically confirmed esophageal squamous cell carcinoma (ESCC) were enrolled and received the study treatment, 5 at the 250 mg dose level and 7 at the 500 mg dose level. Among those 12 pts, 11 were locally advanced ESCCs and 1 was locally recurrent ESCC. The most common AN0025-related adverse events (AEs) were weight decreased (33%), anemia (33%), and white blood cell count decreased (25%). Two pts (17%) experienced Grade ≥3 AN0025-related AEs (one Grade 3 weight decreased and one Grade 3 esophageal fistula). No dose-limiting toxicity occurred at either dose level, and the maximum tolerated dose was not reached. The median follow-up was 14.2 months, with 8 pts remaining on study treatment and a maximum time on treatment of 2 years. The disease control rate (DCR) was 92% (11/12). The median progression-free survival (PFS) was not reached, with 6-month and 1-year PFS rates of 91% and 73%, respectively. The 1-year overall survival (OS) rate was 82%. Additionally, among the 8 pts with measurable lesion(s) at baseline, 1 (13%) achieved confirmed complete response (CR), and 6 achieved partial response (PR), including 5 confirmed PRs, giving an unconfirmed overall response rate (ORR) of 88% (7/8) and a confirmed ORR of 75% (6/8). AN0025 PK approached linearity at both 250 mg and 500 mg QD. AN0025 PK in combination with dCRT showed no interactions. Conclusions: This Phase Ib study suggests that AN0025 plus dCRT exhibits favorable safety and encouraging preliminary efficacy in unresectable locally advanced or locally recurrent EC, warranting further investigation. Clinical trial information: NCT05191667 .