Abstract CT126: A Phase 0 Study of EGF-Depleting Therapy CIMAvax-EGF in Combination With Standard Therapy for RAS- and BRAF Wild-Type Metastatic Colorectal Cancer

Abstract Background: Colorectal Cancer (CRC) is the 3rd most common cancer in the US and a leading cause of cancer-related death. The epidermal growth factor receptor (EGFR) is overexpressed by immunohistochemistry (IHC) in up to 60% of CRC and is a relevant target for treatment. Monoclonal antibodies targeting the EGFR (cetuximab, panitumumab) have been in clinical use since 2004 as single agents as well as in combination with chemotherapeutics for patients with metastatic CRC, however primary and secondary resistance is very common. CIMAvax-EGF® (CIMAvax) vaccinates against one of the main EGFR ligands: the epidermal growth factor (EGF) protein. The vaccine is based on active immunotherapy where an individual’s immune response is manipulated to release its own effector antibodies against circulating EGF. We hypothesize that adding CIMAvax-EGF to standard chemotherapy has the potential to elicit an immune response against EGF for RAS- and BRAF wild-type metastatic CRC. Methods: This is a phase 0 study to evaluate CIMAvax in combination with standard therapy for RAS- and BRAF wild-type metastatic CRC. Patients will be treated with chemotherapy/biologic agent plus CIMAvax 2. 4 mg (DL 1) ; DL -1 is 1. 2 mg. The starting dose is the dose currently established as recommended dose in combination with immunotherapy in patients with non-small cell lung cancer. Cohorts A, B1 and B2 will enroll each 6-12 patients. Based on the known CIMAvax safety profile, we expect to enroll 18-20 patients in these cohorts. Cohort C will enroll 4-6 patients. Cohort A will enroll patients who have not received prior therapy for advanced disease. Patients in Cohort A will be treated with mFOLFOX6/Bevacizumab/CIMAvax at present. Cohort B will enroll patients who have received at least one but no more than 2 prior therapies for advanced disease. Cohort B is comprised of 2 sub-Cohorts. The standard therapy backbone in Cohort B1 will be FOLFIRI/anti-EGFR therapy, and in Cohort B2 mFOLFOX6/anti-EGFR therapy. Cohort C will enroll patients who have not received prior therapy for advanced disease and are candidates for liver metastasectomy. Cohort C will start accruing after the safety run-in phase in Cohorts A, and B2 are completed. The primary objective of this study is to determine the immunogenicity of CIMAvax in the 1st and 2nd/3rd line setting. Secondary objectives include determining the safety and efficacy of these combinations in this patient population and PFS. Exploratory objectives include evaluation of immunomodulation in the tumor microenvironment in patients undergoing metastasectomy of liver metastases, predictive/prognostic role of EGFR ligands (such as EGF, epiregulin, and amphiregulin), somatic mutation profile, EGFR expression by IHC and EGFR copy number alterations/mRNA expression. This trial is currently open for accrual. Clinicaltrials. gov number NCT06011772 Citation Format: Deepak Vadehra, Cayla Janes, Rachel Frascati, Mary Reid, Tania C. Ramos, Sarbajit Mukherjee, Kalet L. Monzón, Patricia L. Alvárez, Orestes S. Morales, Circe M. Pardillo, Christos Fountzilas. A Phase 0 Study of EGF-Depleting Therapy CIMAvax-EGF in Combination With Standard Therapy for RAS- and BRAF Wild-Type Metastatic Colorectal Cancer abstract. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 2 (Late-Breaking, Clinical Trial, and Invited Abstracts) ; 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84 (7Suppl): Abstract nr CT126.