Clinical Validation of HPV ctDNA for Early Detection of Residual Disease Following Chemoradiation in Cervical Cancer

Abstract

Despite chemoradiation (CRT), 30-40% of patients with locally advanced cervical cancer relapse. Most cases are caused by human papilloma virus (HPV), and HPV circulating tumor DNA (ctDNA) may identify patients at highest risk of relapse. Our previous pilot study showed that detectable HPV ctDNA at the end of CRT is associated with inferior progression-free survival (PFS) using digital polymerase chain reaction (dPCR), and that a next generation sequencing approach (HPV-seq) may outperform dPCR. We hypothesized that HPV ctDNA may identify cervical cancer patients at increased risk of relapse following CRT and aimed to prospectively validate HPV ctDNA as a tool for early detection of residual disease. This prospective, multicenter validation study accrued 70 patients with HPV+ stage IB-IVA cervical cancer treated with definitive CRT from 2017-2022. Patients underwent phlebotomy at baseline, end of, 4-6 weeks and 3 months post CRT for HPV ctDNA levels. HPV genotyping was performed on the baseline plasma sample using HPV-seq. HPV genotype-specific DNA levels in plasma were quantified using both dPCR and HPV-seq. PFS was estimated using the Kaplan-Meier method and compared using the log rank test. Multivariable Cox regression analyses incorporating stage and HPV ctDNA detectability assessed independent prognostic factors associated with PFS. At the time of abstract, results for 67 patients were available. The majority had squamous histology (84%) and stage IIB (36%) or IIIC1 (25%) disease. HPV genotyping using HPV-seq revealed 54% (36/67) of cases harboring HPV-16, and 46% harboring other HPV types: 15 HPV-18; 5 HPV-59; 2 HPV-31; 2 HPV-33; 2 HPV-52; 1 each HPV-39, HPV-45, HPV-53, HPV-58, and HPV-82. With a median follow up of 2.2 (range 0.4 - 5.2) years, there were 21 PFS events. Most recurrences (14/21) were distant and/or paraaortic; 4 local and nodal/distant; 2 pelvic nodal; and 1 local. Patients with detectable HPV ctDNA on dPCR at the end of, 4-6 weeks and 3 months post CRT had significantly worse 2-year PFS compared to those with undetectable HPV ctDNA (78 vs 52%, p = 0.04; 82 vs 26%, p < 0.001; and 80 vs 23%, p = < 0.001, respectively). HPV-seq showed similar results (87 vs 55%, p = 0.02; 81 vs 45%, p = 0.003; and 84 vs 31%, p = < 0.001, respectively). On multivariable analyses, detectable HPV ctDNA on dPCR and HPV-seq remained independently associated with inferior PFS (see table). HPV-seq enables HPV genotyping directly from plasma in locally advanced cervical cancer. Persistent HPV ctDNA following CRT is independently associated with inferior PFS in this prospective validation study. HPV ctDNA testing can be used to identify, as early as at the end of CRT, patients at high risk of recurrence in future treatment intensification trials.