Quantitative Dynamic 18F-FDG PET/CT in Survival Prediction of Metastatic Melanoma under PD-1 Inhibitors

Abstract

The advent of novel immune checkpoint inhibitors has led to unprecedented survival rates in advanced melanoma. At the same time, it has raised relevant challenges in the interpretation of treatment response by conventional imaging approaches. In the present prospective study, we explored the predictive role of quantitative, dynamic 18F-fluorodeoxyglucose (18F-FDG) positron emission tomography/computed tomography (PET/CT) performed early during immunotherapy in metastatic melanoma patients receiving treatment with programmed cell death protein 1 (PD-1) inhibitors. Twenty-five patients under PD-1 blockade underwent dynamic and static 18F-FDG PET/CT before the start of treatment (baseline PET/CT) and after the initial two cycles of therapy (interim PET/CT). The impact of semiquantitatively (standardized uptake value, SUV) and quantitatively (based on compartment modeling and fractal analysis) derived PET/CT parameters, both from melanoma lesions and different reference tissues, on progression-free survival (PFS) was analyzed. At a median follow-up of 24.2 months, survival analysis revealed that the interim PET/CT parameters SUVmean, SUVmax and fractal dimension (FD) of the hottest melanoma lesions adversely affected PFS, while the parameters FD of the thyroid, as well as SUVmax and k3 of the bone marrow positively affected PFS. The herein presented findings highlight the potential predictive role of quantitative, dynamic, interim PET/CT in metastatic melanoma under PD-1 blockade. Therefore, dynamic PET/CT could be performed in selected oncological cases in combination with static, whole-body PET/CT in order to enhance the diagnostic certainty offered by conventional imaging and yield additional information regarding specific molecular and pathophysiological mechanisms involved in tumor biology and response to treatment.

Assessment of early metabolic progression in melanoma patients under immunotherapy: an 18F-FDG PET/CT study

“…This finding is consistent with recently published literature investigating spleen metabolism by means of 18 F-FDG PET, which highlighted the significant association between a high SLR and a poor outcome to immunotherapy [ 23 , 49 ]. At the same time, these results should be interpreted with caution, since other studies in the field—although not explicitly involving SLR calculations—have shown a less contributory role of spleen metabolism in differentiating responders from non-responders to ICIs [ 46 , 50 , 51 ], supporting the opinion that spleen metabolism is a “double-edged” biomarker with debatable results [ 52 ]. On the whole, the investigation by means of functional imaging not only of the tumor but also of the patient’s host immune system gradually gains significance as potential surrogate marker of treatment response.…”

A rare case of pancreatic metastasis from malignant melanoma mimicking pancreatitis on 18F-FDG PET/CT

“…Therefore, it is of foremost importance to promptly identify subjects who can benefit from such a therapeutic regimen. 18 F-FDG PET/CT, particularly when specific technical approaches such as dynamic acquisition and analysis of PET-derived parameters are utilized, proved useful to predict MM's response to IT and offers the unique opportunity to get an insight into tumor's biology at a molecular level [4][5][6]. To the best of our knowledge, our case is the first report describing diffuse pancreatic metastatic involvement from MM, evaluated before and after IT through PET/CT imaging.…”

Managing Metastatic Melanoma in 2022: A Clinical Review

“…For example, a prospective study using dynamic 18F-fluorodeoxyglucose positron emission tomography and computed tomography imaging during early phases of systemic ICI in patients with advanced melanoma provided clinical impacts on PFS on the basis of several semiquantitative and quantitative parameters. 177 Additional efforts in examining such an approach may provide further insights into these PFS trends with simultaneous improvements in monitoring treatment responses and guiding therapeutic decisions within this patient population.…”