Yelena Y. Janjigian, MD, who not involved in COMPASSION-15, provided critique of the study, during another session at the meeting, in which she discussed the CheckMate 649 trial. She noted that, although the median OS of 15 months in the COMPASSION-15 study was slightly higher than the OS in the CheckMate 649 trial (approximately 14 months), comparing the results of two studies is challenging.
“In the COMPASSION-15 trial, chemotherapy was stopped after [4.5 months], and only 50% of patients received chemotherapy with subsequent treatment — this is not standard and may limit the comparison with other immunotherapy trials,” explained Dr. Janjigian, who is a gastrointestinal oncologist and was a principal investigator in the phase 3 CheckMate 649 immunotherapy trial for advanced gastric cancer.
Importantly, survival benefit with cadonilimab plus chemotherapy was observed across all prespecified PD-L1 expression levels, including in patients with low PD-L1 expression (PD-L1 combined positive score [CPS] less than 5%). In the low PD-L1 expression group (CPS less than 5%), the median OS was 14.8 months in the cadonilimab group compared with 11.8 months in the placebo group (HR, 0.70; 95% CI, 0.51-0.95; P = .011).
“These positive survival outcomes when cadonilimab was combined with chemotherapy may be attributed to synergistic mechanisms of action, enhanced immune responses, modulation of the tumor microenvironment, and careful patient selection based on biomarker assessments,” noted Dr. Ji, during an interview. “Targeting multiple pathways using bispecific antibodies provides potential synergistic effects, enhancing anti-tumor activity and improving treatment outcomes.”
Cadonilimab Plus Standard Chemotherapy Reduces the Risk of Tumor Progression
In addition to prolonging OS, cadonilimab plus chemotherapy also provided superior PFS and ORR compared to placebo plus chemotherapy.
The median PFS was 7.0 months in the cadonilimab plus chemotherapy group, versus 5.3 months in the chemotherapy-only group (HR, 0.53; 95% CI, 0.44-0.65, P < .001), and the ORR was 65.2% versus 48.9%, respectively. Furthermore, the duration of response was longer with cadonilimab plus chemotherapy than with placebo plus chemotherapy (8.8 versus 4.4 months, respectively).
Toxicities Associated With Cadonilimab Plus Standard Chemotherapy Are Manageable
The safety profile of the cadonilimab plus chemotherapy regimen was manageable, with grade 3 or higher treatment-related adverse events occurring in 71.8% of patients in the cadonilimab group and 60.5% of patients in the placebo group. No new safety signals were observed.
During an interview, Dr. Ji said that the most common adverse events were endocrine toxicity, skin toxicity, and lung toxicity. “These adverse events were managed through close monitoring, symptom management, and appropriate interventions based on the severity and nature of the toxicity experienced by patients,” he explained. He added that this toxicity profile of cadonilimab is similar to the toxicity profiles of approved PD-1 and CTLA-4 inhibitors.
Implications — A New Treatment Paradigm for Advanced Gastric Cancer?
According to Dr. Ji, the interim results from the cadonilimab study suggest that this novel PD-1/CTLA-4 bispecific antibody, in combination with chemotherapy, could become a new standard first-line treatment option for patients with advanced G/GEJ adenocarcinoma, offering a significant survival advantage over chemotherapy alone, regardless of PD-L1 status.
