Circulating Cell-free DNA for Metastatic Cervical Cancer Detection, Genotyping and Monitoring

Purpose: Circulating cell-free (ccf) human papillomavirus (HPV) DNA may serve as a unique tumor marker for HPV-associated malignancies, including cervical cancer. We developed a method to genotype and quantify circulating HPV DNA in patients with HPV16- or HPV18-positive metastatic cervical cancer for potential disease monitoring and treatment-related decision making. Patients and Methods: In this retrospective study, HPV ccfDNA was measured in serum samples from 19 metastatic cervical cancer patients by duplex digital droplet (dd) PCR. Nine patients had received tumor-infiltrating lymphocyte (TIL) immunotherapy. ccfDNA data were aligned with the tumor HPV genotype, drug treatment, and clinical outcome. Results: In blinded tests, HPV ccfDNA was detected in 19/19 (100%) patients with HPV-positive metastatic cervical cancer but not in any of the 45 healthy blood donors. The HPV genotype harbored in the patients' tumors was correctly identified in 87/87 (100%) sequential patient serum samples from 9 patients who received TIL immunotherapy. In three patients who experienced objective cancer regression after TIL treatment, a transient HPV ccfDNA peak was detected 2-3 days after TIL infusion. Furthermore, persistent clearance of HPV ccfDNA was only observed in two patients who experienced complete response (CR) after TIL immunotherapy. Conclusions: HPV ccfDNA represents a promising tumor marker for non-invasive HPV genotyping and may be used in selecting patients for HPV type-specific T cell based immunotherapies. It may also have value in detecting anti-tumor activity of therapeutic agents and in the long-term follow-up of cervical cancer patients in remission.

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