Elevation Oncology, Inc. together with CSPC Pharmaceutical Group Limited announced promising initial clinical data for SYSA1801 (EO-3021) from the ongoing Phase 1 dose escalation and expansion study in China. These data will be presented at the American Society of Clinical Oncology (ASCO) 2023 Annual Meeting, being held June 2-6, 2023, in Chicago, IL. EO-3021 is a potential best-in-class antibody-drug conjugate (ADC) that has been designed to selectively deliver a cytotoxic payload directly to Claudin 18.2-expressing cancer cells to minimize toxicities and maximize anti-tumor activity.

EO-3021 is a fully human monoclonal antibody (mAb) that targets Claudin 18.2 and is site-specifically conjugated to the cytotoxic agent monomethyl auristatin E (MMAE), via a cleavable linker with a drug-to-antibody ratio (DAR) of 2. Elevation Oncology’s partner, CSPC, is actively recruiting patients in the Phase 1 clinical trial of SYSA1801 (EO-3021) in China (NCT05009966). Key Findings from the Phase 1 Study?: As of the data cutoff date of November 5, 2022, 33 patients with resistant/refractory solid tumors that expressed Claudin 18.2 were enrolled; Patients received 0.5 mg/kg to 3 mg/kg of SYSA1801 (EO-3021) administered intravenously (IV) every 3 weeks (Q3W) as part of the dose escalation (n=17) portion of the study; in the dose expansion portion of the study, patients (n=16) were treated at effective doses (2.0 mg/kg IV Q3W and 2.5 mg/kg IV Q3W); 26 patients (78.8%) had gastric cancer (GC); 7 patients (21.2%) had pancreatic cancer; 11 patients (33.3%) had been pretreated with =3 prior lines of therapy; 21 patients (gastric cancer n=17; pancreatic cancer n=4) were evaluable for efficacy per RECIST v1.1; In gastric cancer, the objective response rate (ORR) was 47.1% (8 PRs, including 4 confirmed PRs) and the disease control rate (DCR) was 64.7%, including three patients with stable disease (SD); The overall ORR was 38.1% (8 PRs, including 4 confirmed PRs) and DCR was 57.1% (including 4 SDs); Of the 33 patients enrolled at the time of data cutoff, treatment-related adverse events (TRAEs) of any grade occurred in 25 patients (75.8%), including eight (24.2%) TRAEs of =Grade 3; The most common TRAEs (occurring in >20% of patients) were nausea (42.4%), vomiting (36.4%), dry eye syndrome (21.2%) and anemia (21.2%); Two dose-limiting toxicities (DLTs) of Grade 3 nausea and vomiting occurred at the 3 mg/kg IV Q3W dose; No treatment-related deaths were reported; The dose escalation and expansion portion of the study in China is ongoing. ?

Details for the ASCO 2023 Presentation are as Follows: Title: First-in-human dose escalation and expansion study of SYSA1801, an antibody-drug conjugate targeting claudin 18.2 in patients with resistant/refractory solid tumors. Presenter: Dr. Yakun Wang; Session Type: Poster Discussion Session; Session Title: Molecularly Targeted Agents and Tumor Biology; Poster Session Date and Time: June 3, 2023, 8:00 a.m. – 11:00 a.m. CT; Poster Discussion Date and Time: Saturday, June 3, 2023, at 1:15 p.m. CT; Abstract Number: 3016; Poster Number: 214 . The full presentation can be accessed under the resources and publications page of the Elevation Oncology website following the completion of the presentation session at ASCO.