Abstract 3251: Immediate postoperative minimal residual disease detection with MAESTRO predicts recurrence and survival in head and neck cancer patients

Abstract Introduction: Most head and neck squamous cell carcinoma (HNSCC) patients are diagnosed with locoregionally advanced disease and face high recurrence rates despite standard-of-care treatments. Using circulating tumor DNA (ctDNA) to detect minimal residual disease (MRD) has emerged as a promising biomarker for assessing recurrence risk and treatment efficacy across various cancers. However, the sensitivity of commercially available assays for detecting MRD remains limited, often failing to capture subtle dynamic changes. As a result, the dynamics of ctDNA immediately following treatment and its potential as a reliable biomarker for guiding early post-operative adjuvant treatment decision making remain poorly understood. Methods: Our group has developed MAESTRO (minor-allele-enriched sequencing through recognition oligonucleotides) that uses patient-specific probes to selectively enrich ctDNA carrying thousands of genome-wide tumor mutations, enabling highly sensitive MRD detection with minimal sequencing. We utilized MAESTRO to prospectively monitor MRD in HNSCC patients after surgery during the immediate post-operative window—serial blood samples taken while patients were in the hospital recovering from surgery—and the surveillance period, aiming to evaluate its potential to predict disease progression. Kaplan Meier survival analysis and Cox proportional hazards regression were applied to assess the association of MRD detection during the immediate post-operative window with event-free survival (EFS). Results: 24 HNSCC patients were enrolled. Patients were pre-dominantly HPV-negative [23/24 (95.8%)] and had advanced stage III/IV disease [22/24 (91.7%)]. Serial sampling in the days following surgery revealed rapid ctDNA clearance on the first post-operative blood draw (1-3 days postop) of patients without MRD. MAESTRO detected ctDNA in 13 of the 15 (86.7%) patients who experienced an event (recurrence or death). In 8 of the 13 (61.5%) patients with an event and detectable MRD, tumor fractions were below the limit of detection of leading commercial assays. MRD detection was associated with worse EFS (HR = 27.4; 95% CI 3.5-214.5; P < 0.0001) and remained an independent predictor of EFS when controlling for high-risk pathologic features (23.8; 3.0-192.1; P = 0.003). Conclusions: Tumor fractions of HNSCC patients treated effectively with surgery were undetectable as early as the first postoperative day. Most tumor fraction levels detected by MAESTRO were outside the sensitivity range of leading commercially available assays. MRD detection of patients in the immediate post-operative period was predictive of recurrence and worse survival. MAESTRO-based MRD detection may enable highly-sensitive identification of high-risk HNSCC patients and guide therapy including whether treatment escalation may be necessary. Citation Format: Edward S. Sim, 1 Justin Rhoades, 2 Kan Xiong, 2 Laurel Walsh, 2 Andjela Crnjac, 2 Timothy Blewett, 2 Yana Al-Inaya, 1 Julia Mendel, 1 Daniel Ruiz, 1 Vasileios Efthymiou, 1 Gjystina Lumaj, 1 William J. Benjamin, 1 G. Mike Makrigiorgos, 3 Shervin Tabrizi, 2 Viktor A. Adalsteinsson, 2 Daniel L. Faden1. Immediate postoperative minimal residual disease detection with MAESTRO predicts recurrence and survival in head and neck cancer patients [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2025; Part 1 (Regular Abstracts); 2025 Apr 25-30; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2025;85(8_Suppl_1):Abstract nr 3251.