HPV virus and biomarkers of resistance to chemoradiation in circulating tumor cells from patients with squamous cell carcinoma of the anus

Localized anal cancer is mostly represented by squamous cell carcinoma of the anus (SCCA) and is cured in ≥80 % of cases by chemoradiation (CRT). Development of techniques for detection/evaluating circulating tumor cells (CTCs) for diagnosis/ prognosis/response to therapy can change the manner we treat/follow SCCA patients.

Objective: to detect CTCs from patients with SCCA and evaluate the presence of HPV virus, p16 expression and markers related to resistance to CRT (RAD23B/ ERCC1/ TYMS) in CTCs at baseline and after CRT.

Methods: CTCs were isolated/quantified by ISET®, protein expressions were analyzed by immunocytochemistry and HPV DNA was detected by chromogenic in situ hybridization.

Results: We enrolled 15 patients: median age was 61 (43-73) years, the majority was women (10/15). CTCs were detected in all patients at baseline (median= 0.4 (0.4-3.33) CTCs/mL) and in 8/9 patients, after CRT (median= 2.33 (0-7.0) CTCs/mL). DNA from HPV was found in CTCs in 14/15 patients (93.33 %) at baseline and in 7/9 (77.7 %) after treatment. At a median follow-up of 22.20 (1.45-38.55) months, three patients expressed ERCC1 in CTCs after treatment, with one of them having disease recurrence.

Conclusion: We showed that detection of HPV in CTCs from patients with non-metastatic SCCA is feasible and appears to be a sensitive diagnostic method. These results may be clinically useful for better monitoring these patients. However, future larger cohorts may demonstrate whether there is any correlation between the presence of HPV and the expression of screening markers for CRT in SCCA.