PLUME: A single-arm phase II trial evaluating the combination of pembrolizumab and lenvatinib in metastatic uveal melanoma (mUM) patients (pts) previously treated or not with tebentafusp

TPS9613 Background: Up to 50% of pts with uveal melanoma (UM) develop metastases, mainly hepatic, with poor overall survival and limited treatment options as response rate to first-line immune checkpoint inhibitors (ICI) is low in mUM pts. Tebentafusp, a bispecific T-cell engager, was recently approved in this setting but only in HLA A*02-01+ mUM patients. Lenvatinib is a tyrosine kinase inhibitor targeting multiple growth factor receptors including vascular endothelial growth factor receptors (VEGFRs), fibroblast growth factor receptors (FGFRs) and colony-stimulating factor receptor (CSF1-R), which are key pathways in UM. Lenvatinib showed an immune-modulating effect in preclinical models. The combination demonstrated synergic clinical anti-tumor activity in various tumor types including microsatellite-stable endometrial cancers, kidney cancers and ICI-resistant skin melanomas. We hypothesize that combining pembrolizumab with lenvatinib in mUM may lead to an improved immune response in mUM patients. Methods: Fifty-four, ICI-naïve, metastatic UM pts will be enrolled in this monocentric, single-arm phase II trial at Institut Curie, Paris, France. Because previous exposure to tebentafusp might increase the activity of subsequent ICI, the combination will be assessed in two independent cohorts: cohort 1 with HLA A*02-01 neg , tebentafusp-naive patients (22 assessable patients), and cohort 2 with HLA A*02-01 pos pts previously treated with tebentafusp (28 assessable patients). Up to 54 patients may be included according to an 8% drop-out rate. Each participant will receive pembrolizumab (200 mg Q3W, maximum of 35 cycles) plus lenvatinib (starting at 20mg QD) until reaching a discontinuation criterion. Liver MRI and chest-abdomen-pelvis CT will be performed every 9 weeks until progressive disease. Primary objective is to evaluate the progression-free survival (PFS) after nine cycles of treatment (27 weeks) as assessed by the investigator using the RECIST v1.1. Secondary objectives include PFS according to immune RECIST (iRECIST), overall survival, overall response rate, safety and tolerability, quality of life. Inclusion period started mid-July 2022 for two years. To date, twenty-four (21 in cohort 1, 3 in cohort 2) of planned 54 pts have been enrolled in six months. Biospecimens (longitudinal blood samples and tumor tissue at inclusion) will be collected during the study to allow biomarker research. Clinical trial information: NCT05282901 .