Khalil, Lucien

Abstract Purpose: Relapse is a major cause of failure in human papillomavirus–independent head and neck squamous cell carcinoma. Clinicopathologic criteria for adjuvant treatment remain imprecise and have not changed for decades. We investigated whether ctDNA in lymphatic exudate collected via surgical drains (“lymph”) 24 hours after surgery identified molecular residual disease (MRD) and compared its performance with time-matched plasma. Experimental Design: Using an ultra-sensitive tumor-informed sequencing approach, tumor variants were called in lymph and plasma to classify patients as ctDNA positive or ctDNA negative, trained in an initial cohort of 36 patients, and replicated in an independent cohort of 37 patients. Progression-free survival was compared in ctDNA(+) versus ctDNA(–) patients. Results: Lymph identified MRD in two independent multi-site cohorts (initial cohort sensitivity = 76% and specificity = 63%; log-rank P = 0.01; replication cohort sensitivity = 65% and specificity = 70%; log-rank P = 0.04). Lymph performance was enhanced in locoregional relapse (sensitivity = 78% and specificity = 67%; log-rank P = 0.0004) and generalized to early-stage patients. Analysis of matched plasma collected at this early timepoint was not predictive of recurrence (sensitivity = 35% and specificity = 72%; log-rank P = 0.7). In patients with intermediate-risk pathology, lymph ctDNA was associated with recurrence (sensitivity = 88% and specificity = 67%; log-rank P = 0.0008), suggesting an opportunity for improved stratification of patients who may benefit from additional adjuvant treatment. Conclusions: Postoperative lymph is a novel, proximal, and early source of MRD with the potential to introduce more precision into adjuvant therapy decision-making and improve outcomes, especially for patients with intermediate-risk human papillomavirus–independent head and neck squamous cell carcinoma.

Abstract Recurrence after surgery remains a major cause of failure in head and neck squamous cell carcinoma (HNSCC), particularly for HPV-negative patients whose 2-year failure rate is > 50%. There is unmet need for an accurate diagnostic test that predicts risk of recurrence prior to adjuvant therapy selection. We evaluated ctDNA in lymphatic exudate (“lymph”) collected via surgical drains at 24 hours to detect molecular residual disease (MRD) and compared its performance to plasma and adverse pathology features. Lymph, plasma and blood were collected from 76 HPV- HNSCC patients 24 hours after surgery. Tumor tissue was collected at surgery. 73 patients passed QC. Samples were sequenced using a 699-gene custom panel to a median of 6322x (lymph and plasma cfDNA) or 533x (tumor and blood genomic DNA). Tumor variants were directly genotyped in lymph and plasma using a tumor-informed pipeline. MRD status was determined using a calibrated cutoff based on mean variant allele fraction. Wilcoxon signed-rank test was used for comparisons. Kaplan-Meier estimator with log-rank test and Cox proportional hazards model were used for survival analysis. We previously demonstrated that 24 hour postoperative lymph ctDNA detects recurrence in HPV(-) HNSCC across two independent multi-site cohorts and by orthogonal sequencing approaches (sensitivity (SN) = 72%, specificity (SP) = 65%, p = 0.003, hazard ratio (HR) = 3.1, n = 73). When compared to other data available at this early time point (pathology and 24 hour postoperative plasma), lymph ctDNA outperformed each for recurrence detection (extranodal extension (ENE, p = 0.30), lymphovascular invasion (p = 0.02), perineural invasion (p = 0.38), positive lymph nodes (p = 0.03), plasma (p = 0.8)). We next evaluated lymph ctDNA in a critical subpopulation: patients considered intermediate risk by pathology (negative for ENE or margins but with one or more other adverse pathologic feature). Current NCCN guidelines recommend radiotherapy and to “consider systemic therapy” for these patients. Lymph ctDNA accurately stratified recurrence in this group with high sensitivity (SN = 88%, SP = 69%; P = 0.013, HR = 9.1, n = 24). Within this cohort, 77% of patients who received RT alone and later recurred were positive for lymph ctDNA at 24 hours, suggesting an opportunity to use molecular data in concert with pathology to identify patients who may benefit from adjuvant treatment intensification. Postoperative lymph represents a novel proximal analyte for MRD detection in HPV- HNSCC designed specifically for use in the immediate post-surgical window when adjuvant therapy decisions must be made. Lymph ctDNA is significantly associated with recurrence and outperforms both time-matched plasma and pathology. Accurate MRD identification at this early timepoint has the potential to augment traditional pathology and personalize adjuvant treatment paradigms in HPV-negative HNSCC. Citation Format: Seka Lazare, Zhuosheng Gu, Noah Earland, Adam Harmon, Maciej Pacula, Megan Long, Ashley Tellis, Damion Whitfield, Adam Benson, Lucien Khalil, Robert L. Ferris, Marra Francis, Aadel A. Chaudhuri, Jose P. Zevallos, Wendy Winckler. Postoperative lymphatic exudate in HPV-negative head and neck cancer detects recurrence prior to adjuvant treatment decisions [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 1946.

Abstract Background: Head and neck squamous cell carcinoma (HNSCC) is the sixth most common malignancy globally, and the vast majority of cases are treated with primary surgical resection and adjuvant therapy. Our group has pioneered the use of HNSCC circulating tumor DNA (ctDNA) in surgical effluent collected postoperatively from surgical drains (surgical drain fluid, SDF) as a novel proximal bioanalyte for measuring minimal residual disease after surgery. We now profile the immune cell composition of SDF compared to paired peripheral blood mononuclear cells (PBMCs), and correlate SDF immune cell profiles with clinical variables and oncologic outcomes in HNSCC. Method: SDF and peripheral venous blood were collected 24 hours postoperatively from 58 HNSCC patients, including 11 HPV (+) and 47 HPV (-) patients undergoing standard of care surgical resection, lymph node dissection, and adjuvant therapy. Freshly collected SDF cells and PBMCs were cryopreserved until profiling by multicolor flow cytometry for respective leukocyte compositions. Analyses were used to define the following viable CD45+ leukocyte subsets: total T cells, CD4 T-cells CD8 T-cells, Treg cells, B-cells, non- classical monocytes, classical monocytes, natural killer (NK) cells, classical dendritic cells (cDC), plasmacytoid DC (pDC), macrophages, and monocytic myeloid-derived suppressive cells (MDSCs). Immune cell percentages were correlated with clinical characteristics and cancer recurrence. Results: CD45+ leukocytes comprised >99.5% of SDF cells, with very few EPCAM+ tumor cells (< 10^-4). HPV status did not significantly affect SDF immune cell composition, and no significant differences were noted by tumor site (larynx, oral cavity, oropharynx), or extracapsular lymph node extension. Among 13 HPV (-) HNSCC patients with paired peripheral blood drawn concurrently, SDF had a higher proportion of B-cells(16.8% vs. 9%, p=0.044), NK cells(56% vs. 12%, P<0.001), monocytes(14% vs. 1%, P<0.001), and macrophages(3.1% vs. 0.46%, P<0.001) compared to PBMCs, and a lower proportion of CD4+ T cells(1% vs. 24%, P<0.001), CD8+ T cells(0.6% vs. 18%, P<0.001), MDSCs(2.1% vs. 3.4%, P=0.029), and pDCs(0.1% vs. 0.2%, P=0.014). HPV (-) HNSCC patients that went on to recur (n=9) had a significantly higher proportions of SDF monocytes (total, classical, and non- classical) and CD56dimCD16+ NK cells (all P<0.001) compared to non-recurrent patients (n=38). Patients who went on to recur also had a significantly lower proportion of SDF B-cells (P<0.001), CD56bright NK cells(P=0.01), and macrophages (P=0.018) compared to non- recurrent cases. No significant differences were noted with respect to proportions of CD3+, CD4+, CD8+ T-cells, DC, and MDSC cells. Conclusion: SDF from HNSCC patients contains unique immune cell populations and may provide new insights into postoperative tumor immunity. Differences in SDF immune cell composition by oncologic outcome in patients that go on to recur, highlighting potential prognostic and predictive applications of SDF immune cell profiling for adjuvant therapy decision-making. Citation Format: Zhongping Xu, Noah Earland, Lucien Khalil, Lazar Vujanovic, Danny Azmi Elias, Riyue Bao, Jason J. Luke, Aadel A. Chaudhuri, Jose P. Zevallos. Immune cell composition in surgical drain fluid as a novel prognostic marker in head and neck squamous cell carcinoma [abstract]. In: Proceedings of the AACR Special Conference: Liquid Biopsy: From Discovery to Clinical Implementation; 2024 Nov 13-16; San Diego, CA. Philadelphia (PA): AACR; Clin Cancer Res 2024;30(21_Suppl):Abstract nr B031.