CTC Detection Linked to Relapse in Stage III Melanoma

Anthony Lucci, MD, professor of breast surgical oncology and surgical oncology, The University of Texas MD Anderson Cancer Center

Anthony Lucci, MD

The presence of circulating tumor cell (CTCs) was found to be independently associated with relapse in patients with stage III melanoma, suggesting that CTC assessment may be useful in identify patients who are at risk for relapse and could benefit from adjuvant therapy.¹

In a prospective study, results showed that, through multivariable analysis, the detection of ≥1 CTC was associated with a decreased relapse-free survival (RFS) within 6 months (HR, 3.62; 95% CI, 1.78-7.36; P <.0001). Additionally, in a univariate analysis, patients with ≥1 CTC had a significant decrease in RFS within 54 months of follow-up (HR, 1.69; 95% CI, 1.13-2.54; P = .01).

“Our findings are significant, given that there is a need for blood-based biomarkers to guide clinical decision making for stage III melanoma patients,” lead study author Anthony Lucci, MD, professor of breast surgical oncology and surgical oncology, The University of Texas MD Anderson Cancer Center, stated in a press release.² “There currently are no blood tests available to help doctors accurately tell which patients are likely to relapse, and should be given therapy, and which are low risk, and could be observed.”

Lucci added in the press release that, currently, there is no agreement on when to recommend immunotherapy for node-positive patients with melanoma.

In the prospective study, 243 patients with stage III melanoma participated in the prospective study. Thirty-seven percent of patients had ≥1 CTCs, 17% had ≥2 CTCs, and 5% had ≥3 CTCs per 7.5 mL of blood. At least one baseline CTC was identified in 37% of patients (n = 90). Nineteen percent of patients had stage IIIA disease, 28% stage IIIB, 49% had stage IIIC, and 5% of patients had stage IIID disease.

The mean age of patients was 57 years (range, 20-88) and 61% of patients were male. The median follow-up was 17 months, and 14% of patients experienced relapse within 6 months of baseline CTC assessment.

Fifty-four percent of patients (n = 132) received adjuvant therapy; 6 patients received chemotherapy, 18 patients received targeted therapy, 56 patients received immunotherapy, and 52 patients received other therapies. There were no significant associations between whether or not adjuvant therapy was given, the type of adjuvant therapy administered, and CTC detection, the researchers noted.

The number of CTCs had at baseline corresponding with relapse rates: 0 CTCs (8%), 1 CTC (22.4%), 2 CTCs (24.1%), and ≥3 CTCs (25%). While the authors hypothesized that there is a possible connection between relapse and increasing CTC numbers, a cohort of nonmetastatic patients with melanoma showed that 17% of patients had ≥2 CTCs and 5% of patients had ≥3 CTCs.

Additional results showed that 23% of patients who had ≥1 CTC relapsed within 6 months, compared with 8% who had 0 CTCs. The 6-month RFS rate after baseline was 76% in the ≥1 CTCs group than in those with 0 CTCs (92%; P <.0001).

Forty-eight percent of patients who had ≥1 CTC at baseline relapsed during the full follow-up period compared with 37% of patients who had 0 CTCs. No patients reported adverse events from the blood collection.

“Our analysis demonstrated that CTC detection was significantly associated with a decrease in relapse-free survival at 6 months, and persisted at a 54-month longer-term follow-up,” Lucci added in the press release. “The data from this study provides support for the future pursuit of liquid biopsy techniques to help identify patients most likely to benefit from adjuvant systemic therapy.”

References

1. Lucci, A. Hall, CS, Patel, SP, et al. Circulating tumor cells and early relapse in node-positive melanoma. Clin Cancer Res. 2020;1-31. doi: 10.1158/1078-0432.CCR-19-2670.
2. Study demonstrates liquid biopsy as effective predictor of stage III melanoma relapse and treatment [news release]. The University of Texas MD Anderson Cancer Center. Published February 3, 2020. https://bit.ly/2GY9ffS. Accessed February 4, 2020.