Introduction BIOEMBRACE-I was designed to investigate biomarkers of response and disease control in patients treated with chemo-radiation and MRI guided brachytherapy (BT) for cervix cancer.
Methods Between 2018–2021, eight EMBRACE-I sites contributed tumor tissue for immunohistochemistry (p16, PD-L1 and L1CAM). Biomarkers and clinicopathological factors (FIGO stage, nodal status, histology, necrosis on MR) were used to determine predictors of poor response (high-risk clinical target volume (HRCTV>40cc) at BT and 5-year local, pelvic control and disease-free survival (DFS). Interaction between p16, PDL-1, radiotherapy dose (HRCTV D90) and local control was investigated. Univariate and multivariable analysis (MVA) was performed.
Results Two hundred sixty-four patients were included. The median D90 was 89 (86–95) Gy. P16, PD-L1>1% and L1CAM>10% expression was noted in 81.4%, 17% and 17.4% respectively. P16 -ve status (OR 2.4 (1–5.7), p=0.04), necrosis on MRI (OR=2.1(1.1–4.3), p<0.02) independently predicted for HRCTV-BT >40cc in addition to FIGO stage and tumor width. PD-L1>1% was associated with reduced local (82% vs. 94%, p=0.02) and pelvic control (79% vs 89%, p=0.02). HRCTV D90 <85Gy was associated with inferior 5-year local control in p16+ patients especially if PDL-1 was co-expressed (figure 1). On MVA, PD-L1>1% was the only independent predictive factor for 5-year local event (HR 3.3, p=0.04) and L1CAM for pelvic event (HR 5.5 (1.3–23.3), p =0.02) (table 1).
Conclusion/Implications P16 -ve status and necrosis on MRI independently predict for poor response to EBRT (HRCTV-BT >40cc) and PD-L1 and L1CAM independently predict local and pelvic control suggesting impact of molecular features on radiotherapy response.Further validation is planned in EMBRACE-II.
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