Autor:innen:
Romina Rösch | Department of Clinical Chemistry and Pathobiochemistry, Klinikum rechts der Isar, Technische Universität München | Germany
Irina Kerle | Department of Internal Medicine III - Hematooncology, Klinikum rechts der Isar, Technische Universität München | Germany
Markus Wirth | Department of Otolaryngology, Klinikum rechts der Isar, Technische Universität München | Germany
Markus Nieberler | Department of Oral and Maxillofacial Surgery, Klinikum rechts der Isar, Technische Universität München | Germany
Philipp Blüm | Department of Internal Medicine III - Hematooncology, Klinikum rechts der Isar, Technische Universität München | Germany
Nicole Pfarr | Department of General Pathology and Pathological Anatomy, Technische Universität München | Germany
Carolin Mogler | Department of General Pathology and Pathological Anatomy, Technische Universität München | Germany
Silvia Thoene | Department of Clinical Chemistry and Pathobiochemistry, Klinikum rechts der Isar, Technische Universität München | Germany
Ramona Secci | Department of Clinical Chemistry and Pathobiochemistry, Klinikum rechts der Isar, Technische Universität München | Germany
Dr. med. Andreas Bietenbeck | Department of Clinical Chemistry and Pathobiochemistry, Klinikum rechts der Isar, Technische Universität München | Germany
Christoph Straube | Department of Radiation Oncology, Klinikum rechts der Isar, Technische Universität München | Germany
Clemens Heiser | Department of Otolaryngology, Klinikum rechts der Isar, Technische Universität München | Germany
Klaus-Dietrich Wolff | Department of Oral and Maxillofacial Surgery, Klinikum rechts der Isar, Technische Universität München | Germany
Wilko Weichert | Department of General Pathology and Pathological Anatomy, Technische Universität München | Germany
Stephanie Combs | Department of Radiation Oncology, Klinikum rechts der Isar, Technische Universität München | Germany
Florian Bassermann | Department of Internal Medicine III - Hematooncology, Klinikum rechts der Isar, Technische Universität München | Germany
Prof. Dr. med. Jürgen Ruland | Department of Clinical Chemistry and Pathobiochemistry, Klinikum rechts der Isar, Technische Universität München | Germany
Dr. med. Christof Winter | Department of Clinical Chemistry and Pathobiochemistry, Klinikum rechts der Isar, Technische Universität München | Germany
Background and Objective
For patients diagnosed with head and neck cancer, disease monitoring and detection of tumor recurrence are currently based on clinical examination and imaging. Tumor-derived circulating nucleic acids such as cell-free tumor DNA (ctDNA) can frequently be found in body fluids of cancer patients. Liquid profiling of ctDNA in plasma and in saliva could provide better tumor monitoring and improve the early recurrence detection.Here, we aim to determine to which extent ctDNA and human papillomavirus (HPV) DNA can be detected in plasma and saliva of HNC patients, and which material is more suitable for liquid-based HNC profiling and HPV-related tumor diagnosis. The latter is particularly important as HPV-associated tumors have a better prognosis and might benefit from deescalating therapies.
Methods
In 92 early and late stage HNC patients, blood and saliva samples were prospectively collected after surgery. Samples from all patients were analyzed with digital droplet PCR (ddPCR) assays to detect two TERT promoter hotspot mutations, allowing ctDNA quantification without prior tumor sequencing. In 50 patients with HPV-associated tumor localizations, cell-free DNA (cfDNA) was tested for HPV16 with E7 gene-specific ddPCR primers. In addition, for 9 patients so far, mutations in the primary tumor tissue were identified with panel sequencing (45 genes) to quantify ctDNA using individually designed mutation-specific ddPCR assays.
Results
In 33% (30/92), ctDNA was detected in plasma with mutation-specific ddPCR assays, of which 38% were early tumor stages (I/II). In p16-positive patients (n=16), cell-free HPV16 DNA was detected in plasma in 39% (6/16), of which 50% were early tumor stages. In saliva, ctDNA was detected in 52% (17/33) of samples, and cell-free HPV16 DNA was detected in 15% (4/27) of samples so far. In patients where both plasma and saliva was available, ctDNA detection rate could be improved from 40% (plasma only, 16/40) to 58% (plasma or saliva, 23/40).
In the course of disease, an increase in tumor load could be detected in blood or saliva on average 5.4 months (range 2 weeks to 13 months) earlier than by clinical imaging.
In 63% (10/16) patients out of the p16-positive cohort, we could not detect HPV16-DNA (E7) in plasma and confirm the clinical HPV-positive status which is based on p16 expression as a surrogate marker. However, these patients showed an unfavorable clinical course compared to p16-positive HPV-positive patients (30% died, 79% had a relapse or progressive disease).
Conclusion
Liquid profiling with ddPCR-based detection of ctDNA in blood and saliva is a promising tool for disease monitoring and early recurrence detection in head and neck cancer patients. In HPV-associated tumors, cell-free HPV DNA could be a complementary marker for disease monitoring and for identifying a subgroup of p16-positive tumors that are not driven by HPV infection and hence might benefit from an escalating therapy regime.