Detection of ctDNA in patients with stage III cutaneous melanoma with satellite/in-transit or nodal metastases.

Jafar Al-Mondhiry Inova Schar Cancer Institute, Fairfax, VA info_outline Jafar Al-Mondhiry, Chelsea Stahl, Suraj S. Venna, Sekwon Jang

Authors Jafar Al-Mondhiry Inova Schar Cancer Institute, Fairfax, VA info_outline Jafar Al-Mondhiry, Chelsea Stahl, Suraj S. Venna, Sekwon Jang Organizations Inova Schar Cancer Institute, Fairfax, VA Abstract Disclosures Research Funding No funding received None. Background: Circulating tumor DNA (ctDNA) has emerged as a biomarker to monitor disease status in cancer patients. Limited data exists on the sensitivity of ctDNA for detection of satellite/in-transit or nodal metastases in melanoma. Methods: We conducted a retrospective study of stage III cutaneous melanomas with clinically detected satellite/in-transit and/or lymph node metastases who underwent ctDNA analysis using an mPCR-NGS-based ctDNA assay ("Signatera") prior to surgery or systemic therapy at Inova Schar Cancer Institute. Results: ctDNA was detected in 4 of 14 patients including 1 of 3 patients with both satellite/in-transit metastases and nodal metastases; 3 of 6 patients with nodal metastases only; none of 5 patients with satellite/in-transit metastases only. Nodal tumor burden (sum of short axis of involved lymph nodes) for ctDNA detected patients was greater than 1.5cm (5.0cm, 3.0cm, 3.0cm, and 1.6cm, respectively), and 1.5cm or less in patients whose ctDNA were not detected. Conclusions: ctDNA may not detect satellite/in-transit metastases or small nodal metastases in melanoma. A larger study is needed to validate this finding. Age Sex T stage N stage Nodal metastases (nodal burden) Satellite/in-transit metastases Mutation detected ctDNA detected 71 F T1a N2c Yes (1.5cm) Yes NRAS not detected 59 M T2b N1c No Yes NRAS not detected 45 M T2b N3c Yes (1.1cm) Yes BRAF not detected 80 F T3b N1c No Yes NRAS not detected 51 M T2a N2c No Yes BRAF not detected 78 M T4b N3b Yes (1.0cm) No ARID not detected 78 M T1b N1c No Yes NA* not detected 55 M T3a N1b Yes (1.3cm) No NF1 not detected 64 F Tx N1a Yes (0.7cm) No BRAF not detected 68 M T3a N2c No Yes NRAS not detected 83 F Tx N3b Yes (3.0cm) No BRAF detected (0.05 MTM/mL) 67 M T3a N2b Yes (1.6cm) No NF1 detected (0.66 MTM/mL) 29 M T4b N1b Yes (5.0cm) No NRAS detected (0.15 MTM/mL) 48 F T4b N3c Yes (3.0cm) Yes BRAF detected (7.88 MTM/mL) *NA: Not available.