HPV circulating tumor DNA to monitor response to pembrolizumab and vorinostat combination in patients with advanced HPV-related squamous-cell carcinomas

Abstract

Background: Limited data are available on the role of human papillomavirus circulating tumor DNA (HPV-ctDNA) as a pharmacodynamic marker to monitor the response to treatment in the recurrent/metastatic (R/M) setting. Our study aimed to investigate the sensitivity and pharmacodynamic value of HPV-ctDNA levels during treatment in patients with R/M HPV-related squamous cell carcinoma (SCC) treated with pembrolizumab in combination with vorinostat (PEVO trial, NCT04357873).

Materials and methods: Plasma samples were prospectively collected from 57 patients with HPV-related SCC before treatment initiation and every 6 weeks until disease progression. HPV-ctDNA was quantified by droplet digital PCR. The levels before treatment were analyzed according to the patient and tumor characteristics. Landmark analyses were carried out to study the association between dynamic changes in HPV-ctDNA and progression-free survival (PFS), overall survival (OS), and overall response rate (ORR).

Results: HPV-ctDNA was detected before treatment in all patients (n = 57) with HPV-related SCC. HPV-ctDNA levels correlated with the number of HPV copies in tumor tissue (P < 0.001). Higher levels of HPV-ctDNA in plasma samples were observed in anal cancer than in other tumor types (P < 0.001), and in patients with distant metastases with or without locoregional recurrence than in patients with locoregional recurrence alone (P = 0.02). The increase in HPV-ctDNA levels during treatment was associated with a lower ORR (P = 0.01) and shorter PFS and OS (both P = 0.01).

Conclusion: These findings reveal that dynamic HPV-ctDNA variation levels during treatment have a pharmacodynamic value and may help monitor treatment response in patients with advanced HPV-related SCC from different locations.

Keywords: HPV; biomarker; circulating tumor DNA; immunotherapy; pharmacodynamic; squamous cell carcinoma.

Figure 1

Overview of the study design. Number of patients selected for human papillomavirus circulating tumor DNA (HPV-ctDNA) analysis at different time points (T0 = before treatment initiation; T1 = at the first radiographic evaluation of cycle 3 of treatment; T2 = at the second radiographic evaluation of cycle 5 of treatment; T3 = at disease progression). PD, progressive disease.

Figure 2

HPV-ctDNA detection by droplet digital PCR before treatment. Circles, squares, and triangles correspond to patients with HPV16-related tumors, HPV18-related tumors, and other HPV-related tumors, respectively. (A) HPV-ctDNA levels (log scale) according to different primary tumor locations; the group median is represented by a horizontal bar (Mann–Whitney test). (B) HPV copy number in tumor tissues (log scale) according to different primary tumor locations; the group median is represented by a horizontal bar (Mann–Whitney test). (C) Positive correlation between HPV-ctDNA levels and HPV copy number in tumor tissues (log scale). Spearman’s correlation, r = 0.63 (P < 0.001). ctDNA, circulating tumor DNA; HPV, human papillomavirus.

Figure 3

Evolution of HPV-ctDNA during treatment. (A) Each line represents a single patient (n = 57). The length of each line corresponds to the duration of follow-up. Red (•), green (•), and white (•) circles correspond to an increase in HPV-ctDNA level, a decrease in HPV-ctDNA level, and clearance of HPV-ctDNA, respectively. Time zero indicated the time of enrollment in the study. Blue arrow (→), black cross (x), and plus sign (+) indicate patients alive without PD, disease progression, and death, respectively. (B) Waterfall plot illustrating response according to HPV-ctDNA fold change levels (%) from T0 to T1 in each patient (n = 52). For one patient, the fold change was 5700% and was represented as a fold change of 2100% with an upper horizontal line (-) for graphical reasons. CR, complete response; ctDNA, circulating tumor DNA; HPV, human papillomavirus; PD, progressive disease; PR, partial response; SD, stable disease.

Figure 4

Survival analyses according to HPV-ctDNA variation levels between T0 and T1 across all cohorts. (A) Progression-free survival (n = 40). (B) Overall survival (n = 50). ctDNA, circulating tumor DNA; HPV, human papillomavirus.