EpCAM CAR T (IMC001) for the treatment of advanced GI cancers

4034 Background: EpCAM is highly expressed in various cancer types of the GI system and at metastatic sites. It serves as a promising prognostic/predictive marker (CTC) and therapeutic target. IMC001 is an EpCAM-targeted CAR-T cell that showed promising anti-tumor activities in preclinical studies. Here, we report the results of the low and middle dosage groups in advanced gastric cancers (CT03) and GI cancers (CT04). Methods: This first-in-human, open-label trial involved two separate single-site trials. Both followed a classic 3+3 design with dose escalation of 0.3, 1 or 3 million CAR-T cells/kg after lymphodepletion chemotherapy. CT03 was an IMC001 monotherapy trial (Stage 1) for gastric cancer, while CT04 had Stage 1 and the combination with RFA or microwave ablation (Stage 2) for GI cancers. Eligible patients were those with EpCAM-positive (more than 10%) cancers who had no further standard treatment options and were ECOG 0 or 1. The objective was to assess the safety, PK/PD profile and preliminary efficacy of IMC001. Results: As of January 30, 2023, 12 patients with 6 colorectal and 6 gastric cancers had enrolled, with half receiving 0.3 million and the other half receiving 1 million cells/kg IMC001 infusion. No patient experienced DLT within the 4-week follow-up visits after infusion. All patients experienced ≥Grade 3 hematologic toxicity. One patient in the low-dose group had a SAE of immune hepatitis (Grade 3), which might have been related to cell therapy, and occurred around 11 days after the CAR-T infusion, prolonging the patient's hospitalization. Manageable CRS (Grade 1 to 3) and no ICANS were observed. Other adverse events related to cell therapy were CTCAE Stage 1-2 nausea, vomiting, asthenia, or pruritus, and these recovered quickly. Analyses of the CAR-T cells in peripheral blood revealed robust engraftment in all patients, with the peak number of CAR+ cells reaching on day 5-7 after infusion. CTC remained under the detection limit for more than 40 weeks after cell infusion. Significant elevations of serum levels of IL-6, IP-10, IFN-γ, IL-15, and MCP-1 were observed in most patients. Preliminary efficacy data showed that 2 out of 6 advanced gastric cancer patients were evaluated as PR and 3 remained SD by RECIST 1.1 at the low and middle dosages (CT03). The first PR patient received a second IMC001 infusion on week 50 and had survived for more than 60 weeks. The second PR patient underwent successful surgical removal of the stomach 28 weeks after IMC001 infusion. The CT04 trial is ongoing. Conclusions: This is the first CAR-T therapy ever tested in humans targeting the EpCAM. IMC001 showed a favorable safety profile and reasonable anti-tumor activities at the low and middle dosage levels in patients with advanced EpCAM+ GI cancers, especially in gastric cancer. In addition, our trial has successfully provided a surgical treatment opportunity after CAR-T therapy downstaging of unresectable gastric cancers. Updated data from open cohorts will be presented. Clinical trial information: NCT05028933 .