Muhammad K. Khattak, Edith Cowan UniversityFollow
Anna L. Reid, Edith Cowan UniversityFollow
James Freeman, Edith Cowan UniversityFollow
Michelle Pereira, Edith Cowan UniversityFollow
Ashleigh McEvoy, Edith Cowan UniversityFollow
Johnny Lo, Edith Cowan UniversityFollow
Markus Frank, Edith Cowan UniversityFollow
Isaac Spencer, Edith Cowan UniversityFollow
Mel Ziman, Edith Cowan UniversityFollow
Elin Gray, Edith Cowan UniversityFollow
James Freeman Orcid: https://orcid.org/0000-0001-8065-8416 Ashleigh McEvoy Orcid: https://orcid.org/0000-0001-5692-1317 Johnny Lo Orcid: https://orcid.org/0000-0003-1913-5354 Mel Ziman Orcid: https://orcid.org/0000-0001-7527-3538 Elin Gray Orcid: https://orcid.org/0000-0002-8613-3570
School of Medical and Health Sciences / School of Engineering
NHMRC : 1013349
BACKGROUND: PD-1 inhibitors are routinely used for the treatment of advanced melanoma. This study sought to determine whether PD-L1 expression on circulating tumor cells (CTCs) can serve as a predictive biomarker of clinical benefit and response to treatment with the PD-1 inhibitor pembrolizumab.
METHODS: Blood samples were collected from patients with metastatic melanoma receiving pembrolizumab, prior to treatment and 6-12 weeks after initiation of therapy. Multiparametric flow cytometry was used to identify CTCs and evaluate the expression of PD-L1.
RESULTS: CTCs were detected in 25 of 40 patients (63%). Patients with detectable PD-L1
CONCLUSION: Our results reveal the potential of CTCs as a noninvasive real-time biopsy to evaluate PD-L1 expression in patients with melanoma. PD-L1 expression on CTCs may be predictive of response to pembrolizumab and longer PFS.
IMPLICATIONS FOR PRACTICE: The present data suggest that PD-L1 expression on circulating tumor cells may predict response to pembrolizumab in advanced melanoma. This needs further validation in a larger trial and, if proven, might be a useful liquid biopsy tool that could be used to stratify patients into groups more likely to respond to immunotherapy, hence leading to health cost savings.
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