Biomarker Expression and Clinical Outcomes in International Study of Chemoradiation and Magnetic Resonance Imaging-Based Image-Guided Brachytherapy for Locally Advanced Cervical Cancer: BIOEMBRACE.

Purpose: BIOEMBRACE was designed to study the impact of biomarkers in addition to clinicopathological factors on disease outcomes in patients treated with chemoradiation and magnetic resonance imaging (MRI)-guided brachytherapy (BT) for locally advanced cervical cancer in the EMBRACE study.

Methods and materials: Between 2018 and 2021, 8 EMBRACE-I sites contributed tumor tissue for the immunohistochemistry of p16, PD-L1, and L1CAM. These biomarkers and clinicopathological factors (International Federation of Gynecology and Obstetrics 2009 stage, nodal status, histology, and necrosis on MRI) were analyzed to predict poor response at BT (high-risk clinical target volume [HR-CTV] ≥ 40 cc) at BT) and 5-year local control, pelvic control, and disease-free survival. Interaction between p16, PD-L1, radiation therapy dose (HR-CTV D90), and disease outcomes was investigated. Univariable and multivariable analyses were performed.

Results: Two hundred sixty-four patients were included. The median HR-CTV D90 was 89 Gy (86-95). P-16 positive status, PD-L1 > 1%, and L1CAM ≥ 10% was noted in 86.6%, 20.1%, and 17.8% of patients, respectively. P16 negative status (odds ratio, 2.0; 95% CI, 1.0-5.7; P = .04) and necrosis on MRI (odds ratio, 2.1; 95% CI, 1.1-4.3; P < .02) independently predicted for HR-CTV ≥ 40 cc, as did the International Federation of Gynecology and Obstetrics stage and tumor width >5 cm. PD-L1 > 1% was associated with reduced local (82% vs 94%; P = .02) and pelvic control (79% vs 89%; P = .02). HR-CTV D90 < 85 Gy was associated with inferior 5-year local control in p16-positive patients, especially if PD-L1 was coexpressed. On multivariable analysis, PD-L1 > 1% was the only independent factor for 5-year local control (hazard ratio, 3.3; P = .04) and L1CAM ≥ 50% for pelvic control (hazard ratio, 5.5; 95% CI, 1.3-23.3; P = .02).

Conclusions: P16 negative status and tumor necrosis on MRI are independently associated with poor response to chemoradiation, whereas PD-L1 > 1% and L1CAM ≥ 50% have an independent impact on local and pelvic control, suggesting an impact of biomarker expression on outcomes. Further validation is needed.