Programmed death ligand-1 PET imaging in patients with melanoma: a pilot study

Area of Science:

• Oncology
• Nuclear Medicine
• Immunotherapy

Background:

• Programmed death ligand-1 (PD-L1) expression in melanoma is heterogeneous and challenging to assess with standard biopsies.
• Noninvasive imaging offers a way to evaluate PD-L1 expression across multiple lesions.
• Assessing PD-L1 expression is crucial for guiding immunotherapy treatment decisions.

Purpose of the Study:

• To evaluate the feasibility of positron emission tomography (PET) imaging with [18F]-BMS-986229 for noninvasively assessing PD-L1 expression in advanced melanoma patients.
• To longitudinally track PD-L1 expression heterogeneity in lesions during combination immunotherapy (nivolumab and ipilimumab).
• To examine the relationship between PD-L1 PET uptake and clinical response to immunotherapy.

Main Methods:

• A prospective pilot trial involving 10 patients with advanced melanoma receiving nivolumab and ipilimumab.
• PD-L1 PET imaging using [18F]-BMS-986229 was performed at baseline and 6 weeks after treatment initiation.
• PD-L1 PET uptake (SUVmax) was correlated with radiographic response (RECIST) and baseline PD-L1 by immunohistochemistry (IHC).

Main Results:

• [18F]-BMS-986229 showed variable lesion uptake at baseline (median SUVmax 3.6), decreasing after 6 weeks of treatment in most lesions.
• Patients with higher baseline PD-L1 PET uptake (mean SUVmax ≥ 3.00) in evaluable lesions were more likely to respond to therapy.
• Higher baseline SUVmax correlated with greater individual lesion reduction; PD-L1 PET showed low correlation with IHC-based PD-L1 expression.

Conclusions:

• PD-L1 PET imaging with [18F]-BMS-986229 is a feasible noninvasive method to assess PD-L1 expression and heterogeneity in melanoma patients undergoing immunotherapy.
• This imaging approach may help monitor treatment response and understand PD-L1 dynamics.
• Larger studies are needed to confirm the utility of [18F]-BMS-986229 PET in managing immunotherapy.