RG7802 (also known as CEA CD3 TCB or RO6958688) is an investigational antibody-based cancer therapy being developed by Hoffmann-La Roche. It is currently being studied for the treatment of several types of solid tumors that produce a cell-surface protein called carcinoembryonic antigen (CEA). CEA is found in excess in several types of cancer.
How RG7802 works
RG7802 is a bispecific antibody, which is a protein engineered to bind simultaneously to two different target molecules. It is designed to bind simultaneously to CEA on tumor cells and to the CD3 receptor present on specialized immune cells called T-cells. This brings T-cells into close proximity to the cancer cells. RG7802 potentially leads to T-cell activation, migration to the tumor microenvironment, and subsequent tumor cell killing.
RG7802 in clinical trials
Preclinical studies demonstrated that RG7802 led to effective anti-tumor activity in solid tumors that were poorly infiltrated by immune cells.
An ongoing open-label, multicenter, dose-escalation Phase 1 clinical trial (NCT02324257) aims to evaluate the safety and anti-tumor activity of RG7802 as a single agent in patients with advanced CEA-positive solid tumors that have progressed on standard treatment. The study is currently recruiting patients across the U.S., Canada, and Europe, and is expected to be completed by 2018.
Another ongoing open-label, multicenter, dose-escalation Phase 1b expansion trial (NCT02650713) is evaluating the safety and anti-tumor activity of RG7802 in combination with Tecentriq (atezolizumab) in patients with advanced CEA-positive solid tumors, including metastatic colorectal cancer (mCRC) that has progressed after at least two prior chemotherapy cycles. The study is currently recruiting patients across the U.S., Canada, and Europe, and is expected to be completed by 2019.
Preliminary results from both studies demonstrated the potent anti-tumor activity of RG7802 at doses of 60 mg or above, with immune cells populating the tumor within few days. RG7802’s anti-tumor activity was further enhanced when used in combination with Tecentriq, and it had a manageable safety profile.
In a subgroup of 31 patients with mCRC treated with RG7802 as a single agent at a dose above 60 mg, 45% of patients showed either a partial response or stable disease. In the subgroup of 11 patients treated with RG7802 at doses of 80 and 160 mg combined with Tecentriq, 82% of patients showed a partial response or stable disease.
Another open-label, multicenter, randomized Phase 1b/2 study (NCT03337698) aims to evaluate the safety and effectiveness of several immunotherapy combinations including RG7802 in patients with advanced non-small cell lung cancer. The trial is currently recruiting participants in the U.S., Australia, South Korea, and Europe, including the U.K.
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