PD-L1 mRNA Expression and Treatment Response in Triple-Negative Breast Cancer
Posted: Friday, March 5, 2021
Many patients with unresectable locally advanced triple-negative breast cancer have reaped survival benefits from treatment with atezolizumab plus nab-paclitaxel; however, its use has been hampered by the lack of reliable predictors of tumor response. Gian P. Spinelli, MD, PhD, of the Sapienza University of Rome, and colleagues conducted a study to determine whether the level of PD-L1 mRNA expression in plasma-derived exosomes may predict responses to anti–PD-L1 antibodies early in the course of therapy. Their results, which were presented during the European Society for Medical Oncology (ESMO) Targeted Anticancer Therapies (TAT) Virtual Congress 2021 (Abstract 23P), suggested that patients with higher expression levels at baseline may exhibit a better response to treatment.
A total of 77 patients who were treated with atezolizumab plus nab-paclitaxel participated in the study. Blood samples were collected at baseline as well as after 28 and 56 days of treatment. Patients with complete and partial responses at baseline seemed to display significantly higher levels of PD-L1 mRNA expression compared with those with stable or progressive disease (P < .001). In patients with complete and partial responses, the mean levels of PD-L1 mRNA at baseline and 2 months were 747.6 and 125.4 copies/mL, respectively (P = .001).
The mean number of PD-L1 mRNA copies/mL in patients with stable disease was higher at baseline than at 2 months (270.0 vs. 217.5; P = .614); however, this did not seem to hold in those with progressive disease (122.1 vs. 494.3, respectively; P < .001). In patients with increased levels of PD-L1 mRNA expression after treatment, the duration of progression-free (P = .007) and overall (P = .001) survival seemed to be significantly shorter compared with those who did not show such an increase.
Disclosure: The study authors reported no conflicts of interest.
