The Impact of Liquid Biopsy in Advanced Ovarian Cancer Care

Abstract

Introduction: Ovarian cancer is the third most common gynaecological cancer and has a very high mortality rate. The cornerstone of treatment is complete debulking surgery plus chemotherapy. Even with treatment, 80% of patients have a recurrence. Circulating tumour DNA (ctDNA) has been shown to be useful in the control and follow-up of some tumours. It could be an option to define complete cytoreduction and for the early diagnosis of recurrence.

Objective: We aimed to demonstrate the usefulness of ctDNA and cell-free DNA (cfDNA) as a marker of complete cytoreduction and during follow-up in patients with advanced ovarian cancer.

Material and methods: We selected 22 women diagnosed with advanced high-grade serous ovarian cancer, of which only 4 had complete records. We detected cfDNA by polymerase chain reaction (PCR), presented as ng/mL, and detected ctDNA with droplet digital PCR (ddPCR). We calculated Pearson correlation coefficients to evaluate correlations among cfDNA, ctDNA, and cancer antigen 125 (CA125), a biomarker.

Results: The results obtained in the evaluation of cfDNA and ctDNA and their correlation with tumour markers and the radiology of patients with complete follow-up show disease progression during the disease, stable disease, or signs of recurrence. cfDNA and ctDNA correlated significantly with CA125. Following cfDNA and ctDNA over time indicated a recurrence several months earlier than computed tomography and CA125 changes.

Conclusion: An analysis of cfDNA and ctDNA offers a non-invasive clinical tool for monitoring the primary tumour to establish a complete cytoreduction and to diagnose recurrence early.

Keywords: advanced ovarian cancer; cancer care; liquid biopsy; translational research.

Figure 1

(A) Summary of patient 5’s clinical information, including the treatment type and dates (treatment dates indicated by the coloured vertical stripes; the date of the cytoreduction surgery is indicated by a red vertical line, and the date of the diagnosed recurrence is indicated by a red cross) as well as computed tomography images and summarised results. (B) Cell-free DNA (cfDNA) plasma levels are presented as ng/mL. (C) Circulating tumour DNA (ctDNA) plasma levels are expressed as the number of mutated copies/mL of plasma. Replicates were used to quantify the average TP53 R175H copies for each time point, and the error bars represent the standard deviation across replicates; no bar indicates that the standard deviation was too low to be visualised on the scale used. The volume-adjusted limit of detection was 21.2 GEs (genome equivalent)/mL for all time points. A two-tailed t-test was used to compare the ctDNA levels between sequential time points. (D) Cancer antigen 125 (CA125) serum levels (U/mL); data from multiple replicates were not provided. * p = 0.05.

Figure 2

The number of TP53 (R175H) copies quantified by digital droplet polymerase chain reaction.

Figure 3

(A) Summary of patient 11’s clinical information, including the treatment type and dates (treatment dates indicated by the coloured vertical stripes; the date of the cytoreduction surgery is indicated by a red vertical line, and the date of a diagnosed relapse is indicated by a red cross) as well as computed tomography images and summarised results. (B) Cell-free DNA (cfDNA) plasma levels are presented as ng/mL. (C) Circulating tumour DNA (ctDNA) plasma levels are expressed as the number of mutated copies/mL. Replicates were used to quantify the average BRCA1 E272* (c.814 G>T) levels for each time point, and the error bars represent the standard deviation across replicates; no bars indicate that the standard deviation was too low to be visualised on the scale used. The volume-adjusted limit of detection was 21.2 GE/mL for all time points. A two-tailed t-test was used to compare the ctDNA quantities between sequential time points. (D) Cancer antigen 125 (CA125) serum levels (U/mL); data from multiple replicates were not provided. * p < 0.05, ** p < 0.01, and *** p < 0.001.

Figure 4

The number of BCRA1 E272* (c.814 G>T) copies quantified by digital droplet polymerase chain reaction.

Figure 5

(A) Summary of patient 10’s clinical information, including the treatment type and dates (treatment dates indicated by the coloured vertical stripes, and date of the cytoreduction surgery indicated by a red vertical line) as well as a computed tomography scan and summarised results. (B) Cell-free DNA (cfDNA) plasma levels are presented as ng/mL. (C) Circulating tumour DNA (ctDNA) plasma levels are expressed as the number of mutated copies/mL. Replicates were used to quantify the average TP53 G245 levels for each time point, and the error bars represent the standard deviation across replicates (n = 3); no bars indicate that the standard deviation was too low to be visualised on the scale used. The volume-adjusted limit of detection was 21.2 GE/mL for all time points. A two-tailed t-test was used to compare the ctDNA quantities between sequential time points. (D) Cancer antigen 125 (CA125) serum levels (U/mL); data from multiple replicates were not provided. * p < 0.05, ** p < 0.01, and *** p < 0.001.

Figure 6

(A) Summary of patient 8’s clinical information, including the treatment type and dates (treatment dates indicated by the coloured vertical stripes; the date of the cytoreduction surgery is indicated by a red vertical line, and the date of a diagnosed relapse is indicated by a red cross) as well as computed tomographic images and summarised results. (B) Cell-free DNA (cfDNA) plasma levels are presented as ng/mL. (C) Circulating tumour DNA (ctDNA) plasma levels are expressed as the number of mutated copies/mL. Replicates were used to quantify the average TP53 (c.994C-1G) levels for each time point, and the error bars represent the standard deviation across replicates (n = 3); no bars indicate that the standard deviation was too low to be visualised on the scale used. The volume-adjusted limit of detection was 21.2 GE/mL for all time points. A two-tailed t-test was used to compare the ctDNA quantities between sequential time points. (D) Cancer antigen 125 (CA125) serum levels (U/mL); data from multiple replicates were not provided. * p < 0.05, ** p < 0.01, and *** p < 0.001.

Figure 7

Aggregated correlation between (A) cell-free DNA (cfDNA) and CA125 and (B) TP53-ctDNA and CA125 for the four patients with complete records.

Figure 8

Aggregated correlation between (A) cfDNA and CA125 and (B) TP53-ctDNA and CA125 for eleven different patients of the dataset.

Figure 9

Aggregated correlation between (A) cfDNA and CA125 and (B) TP53 ctDNA and CA125 for two patients with the same disease progression on treatment.

Figure 10

Monitoring cell-free DNA (cfDNA) and cancer antigen 125 (CA125) over time in patient 5.

Figure 11

Monitoring cell-free DNA (cfDNA) and cancer antigen 125 (CA125) over time in patient 11.

Figure 12

Monitoring cell-free DNA (cfDNA) and cancer antigen 125 (CA125) over time in patient 8.