Age Does not Affect the Efficacy of Antibody Drug Conjugates, But is Associated with High-Grade Adverse Events in Patients with Cancer Enrolled in Early Phase Clinical Trials.

Background: Data on the use of antibody drug conjugates (ADCs) in older patients are scarce.

Objective: The objective was to study the safety and efficacy of ADCs used in early phase clinical trials in patients aged ≥ 65 years compared with younger patients.

Patients and methods: All patients enrolled in early phase clinical trials (phase I or II) of ADCs for solid tumors in our institution between November 2014 and May 2023 were included in this retrospective monocentric study. Safety and efficacy were compared between patients ≥ 65 and < 65 years old (y.o).

Results: A total of 136 patients were included in our study, with 43 (31.6%) patients aged ≥ 65 y.o. In comparison with the younger population, patients aged 65 years or older had similar demographic characteristics. Older patients experienced the same rate of all-grade adverse events (95.3 versus 97.8%) and all-grade related adverse events (65.1 versus 66.7%) but more high-grade adverse events (41.9 versus 30.1%) than younger patients. In the univariate analysis, we identified age, taken as a continuous variable, as associated with high-grade adverse event (p = 0.047). No statistically significant difference was found between older and younger patients in terms of disease control rate (65 versus 54%), median progression-free survival (2.76 months [95% confidence interval, 95% CI 1.64-3.75] compared with 2.56 [95% CI 1.81-2.79], p = 0.34), or median overall survival (6.57 months [95% CI 4.01-13.01] compared to 7.89 [95% CI 6.83-9.36], p = 0.65).

Conclusions: In our cohort, ADC therapy provided comparable survival benefits for the older patients but with a higher risk of high-grade adverse event.