Unpacking the Latest Research in Gastrointestinal Cancers

In season 4, episode 1 of Targeted Talks, Benjamin L. Schlechter, MD, senior physician at Dana-Farber Cancer Institute and instructor in Medicine at Harvard Medical School, discuses new studies in the gastrointestinal cancers space. Schlechter explains how these studies can inform future research.

First, in a phase 1a/1b study (NCT03860272) of botensilimab (AGEN1181) plus balstilimab (AGEN2034), promising clinical activity and durable responses were shown in patients with metastatic heavily pretreated patients with microsatellite stable (MSS) colorectal cancer (CRC). The findings were presented at the American Society of Clinical Oncology Gastrointestinal Cancers Symposium (ASCO GI). Schlecter explains that botensilimab is a first-in-class drug targeting the CTLA-4 protein receptor, and therefore offers something different than the anti-CTLA-4 therapies that are currently available.¹

“I don't think anyone expected things like this to work, because there have been so many failures in this space. I think it emphasizes that this is not just a CTLA-4 inhibitor, and not just a checkpoint inhibitor. There’s something fundamentally different about how this agent behaves. We see that in the efficacy profile and the toxicity profile. And I think it's easy to put this in the same basket as tremelimumab [Imjudo], or ipilimumab [Yervoy], and I don't think that's fair assessment. It's a next class of drug, and it really is its own thing,” Schlechter says.

In another early-phase study (TACTIC-02; NCT04727151), investigators are exploring the use of autologous T cells expressing T-cell antigen couple (TAC) that target HER2 in patients with solid tumors. Schlechter says that T-cell therapy is difficult in solid tumors, but if this study is successful, it will create opportunities for other targeted therapy studies in the future.²

Schlechter says: “I think this is a really important beginning. If we can target HER2 safely and successfully, this really opens the door for a number of targets that right now are off limits. There are so many cancers right now that we know there's a target for, but we can't go after that target because there's so much targeting normal tissue that it will be dangerous to do so. This is both an important innovation in T-cell therapy and HER2. But this is also important innovation for cellular therapy in oncology because products like this would allow us to target far more things than we currently can with existing technology.”

Schlechter also discusses later-phase trials that appear to be practice-changing. The SUNLIGHT study (NCT04737187), for example, may have global implications for adding bevacizumab (Avastin) to the combination of trifluridine/tipiracil (Lonsurf) for the treatment of metastatic CRC. This strategy is already standard in the United States. In addition, adding liposomal irinotecan to 5-fluorouracil with leucovorin plus oxaliplatin (NALIRIFOX) may achieve better efficacy compared with standard treatment, as shown in the NAPOLI-3 study (NCT04083235) in patients with pancreatic ductal adenocarcinoma.

_REFERENCES:

_{1. El-Khoueiry AB, Fakih M, Gordon MS, et al. Results from a phase 1a/1b study of botensilimab (BOT), a novel innate/adaptive immune activator, plus balstilimab (BAL; anti-PD-1 antibody) in metastatic heavily pretreated microsatellite stable colorectal cancer (MSS CRC). J Clin Oncol. 2023; 41(suppl 4): LBA8. doi: 10.1200/JCO.2023.41.3_suppl.LBA8}

_{2. Schlechter BL, Olson D, Sailbil S, et al. A phase I/II trial investigating the safety and efficacy of autologous TAC T cells targeting HER2 in relapsed or refractory solid tumors. J Clin Oncol. 2023;41(suppl 4): TPS816. doi: 10.1200/JCO.2023.41.4_suppl}