Aparna R. Parikh, MD
Aparna R. Parikh, MD, Assistant Professor of Medicine, Harvard Medical School, and Director of the Massachusetts General Hospital Cancer Center’s Global Cancer Care Program, Boston, shared her thoughts on the C-800 study of balstilimab plus botensilimab with The ASCO Post.
Noting that the population included patients with advanced or metastatic colorectal cancer whose tumors were microsatellite stable (MSS), Dr. Parikh commented on the lack of progress in this subset of patients. “We haven’t made much headway to date in MSS tumors, which is unfortunately most patients with colorectal cancer. For patients with microsatellite instability–high tumors, we have seen tremendous advances in both the metastatic and neoadjuvant settings; however, this is a minority of patients.”
“We have seen many combination attempts in MSS colorectal cancer ultimately not pan out. Looking back at some of these efforts, we see that patients without liver metastases seemed to do better with such approaches…. What is notable in the study by El-Khoueiry et al is the difference in efficacy in patients with and without liver metastases,” Dr. Parikh observed. She posited that the presence of liver metastases somehow may hinder the ability to mount an immune response.
“It’s not clear how much the Fc engineering of the CTLA-4 agent is adding [to efficacy]…. Could we have seen the same benefit in patients without liver metastases with first-generation CTLA-4/anti–PD-1 combinations?” she questioned.
“This study is one of the more compelling pieces of data we have seen in some time,” Dr. Parikh concluded. “The toxicity profile is notable but seems to be manageable with aggressive recognition and treatment, particularly of colitis. We look forward to the phase II study.”
DISCLOSURE: Dr. Parikh reported no conflicts of interest.
In heavily pretreated patients with metastatic colorectal cancer who have microsatellite-stable tumors, the novel combination of the monoclonal antibodies botensilimab and balstilimab showed clinical activity, producing durable responses and an estimated 63% overall survival rate at 12 months,...