Paz J. Vellanki, MD from U.S. Department of Health and Human Services discusses an ASCO 2020 abstract entitled Evaluation of the correlation between antibiotic use and survival in patients with recurrent or metastatic head and neck squamous cell carcinoma (R/M HNSCC) treated with immune checkpoint inhibitors (ICIs)
Latest evidence indicates that systemic antibiotic (Abx) therapy interferes with the intestinal microbiome and may be associated with reduced survival in patients undergoing ICI care for advanced cancers, like R / M HNSCC. A possible confounder, however, is that the use of Abx identifies a subgroup of patients with a worse prognosis. The association between the use and survival of Abx for ICIs and other medications used to treat patients with R / M HNSCC has been investigated by the FDA.
Compared with chemotherapy and/or cetuximab (Control group), data submitted to the FDA from three randomized controlled trials with ICI as a single agent or with chemotherapy (ICI group) were pooled. The association of systemic Abx use for ICI and control groups within 30 days of initiation of anticancer therapy and survival was evaluated using Kaplan-Meier (KM) estimates and compared using Cox proportional hazard regression models, ECOG output control, therapy line, HPV status, PD-L1 expression, and other significant prognostic factors.
Abx was obtained by 36 percent and 46 percent of patients in the ICI and Control classes, respectively. The KM-estimated median overall survival (OS) gap for the ICI community was 5.6 months based on receipt of Abx (hazard ratio [HR] 1.70). For the Control group, Abx had no effect on OS. For progression-free survival (PFS), similar patterns have been observed.
In this exploratory study, systemic Abx was correlated with reduced survival in patients treated with ICIs relative to patients who did not receive Abx within 30 days of starting care for R / M HNSCC. In the control group, the use of Abx had no noticeable difference in survival. For patients with R / M HNSCC treated with ICIs, further review of the relationship between Abx use and clinical outcomes is required.