61O - Updated results of a phase II trial evaluating an anti-EpCAM x anti-CD3 bispecific antibody, M701, for the treatment of malignant ascites

Background

We present updated results from a prospective randomized controlled phase II Trial (NCT06266091) of an anti-EpCAM x anti-CD3 bispecific antibody, M701, in advanced solid tumors patients (Pts) with malignant ascites (MA).

Methods

Pts with MA due to epithelial cancer were enrolled and randomly assigned to Arm 1 and Arm 2. Arm 1 received intraperitoneal infusions of M701 after paracentesis. The Arm 2 received the paracentesis alone. Both arms received systemic regimens during the trial. The primary endpoint is Puncture-free survival (PuFS), defined as the time of last drainage to the next puncture or death, whichever occurred first. Other endpoints, such as overall survival (OS) and adverse events were also evaluated.

Results

As of Jul 3, 2024, a total of 84 pts were enrolled, with 43 in Arm 1 and 41 in Arm 2. The updated PuFS data showed significantly improvement in the Arm 1 (median 75 days) versus the Arm 2 (median 23 days) (hazard ratios (HR) = 0.40, 95% CI 0.21-0.76, p=0.0085). All three types of cancer pts (gastric, colorectal and ovarian) benefited from M701 infusion with HR <0.5. Matured OS data still demonstrated a trend towards prolonged survival in the Arm 1 (median 111 days versus 86 days) (HR=0.65, 95% CI 0.39-1.09, p=0.102). The 6-month survival rates were 32.3% and 12.6% respectively. Subgroup analysis showed that pts with ≥ 13% relative lymphocyte count (RLC) in peripheral blood received more benefit in PuFS (86 days versus 26 days, HR = 0.23, 95% CI 0.07-0.75, p= 0.014) and OS (139 days versus 82 days, HR = 0.51, 95% CI 0.28-0.92, p= 0.026). In this subgroup, all three types of cancer pts showed prolonged survival with HR<0.6. ≥ Grade 3 TEAE incidence remained the same as prior report while the SAE incidence in Arm 1 increased to 50% (versus 50% in Arm 2). There was no ≥ Grade 3 CRS and the incidence of CRS was 6% in 50 M701 treated pts (including 7 pts transferred from Arm 2 after re-puncture).

Conclusions

Updated results further demonstrated the efficacy of M701 infusion in controlling MA. The ≥ 13% RLC subgroup pts received better benefit in PuFS and significant benefit in OS, which is consistent with the mechanism of action of M701. Those findings are encouraging and support further clinical trials of M701.

Clinical trial identification

NCT06266091 Last updated posted 2024-02-20.

Editorial acknowledgement

Legal entity responsible for the study

Wuhan YZY Biopharma Co., Ltd.

Funding

Wuhan YZY Biopharma Co., Ltd.

Disclosure

P. Zhou: Financial Interests, Personal, Ownership Interest: Wuhan YZY Biopharma Co., Ltd. S. Huang, X. Wang: Financial Interests, Personal, Full or part-time Employment: Wuhan YZY Biopharma Co., Ltd. All other authors have declared no conflicts of interest.