Christos Sachpekidis, Abstract Co-Author: Nothing to Disclose

Uwe Haberkorn MD, Abstract Co-Author: Nothing to Disclose

Lionel Larribere, Abstract Co-Author: Nothing to Disclose

Georgia Dimitrakopoulou MD, Presenter: Nothing to Disclose

Antonia Dimitrakopoulou-Strauss, Abstract Co-Author: Nothing to Disclose

Jessica Hassel, Abstract Co-Author: Nothing to Disclose

Ipilimumab is a newly approved immunotherapeutic agent that provides a clear survival benefit for patients with metastatic melanoma. 18F-FDG PET/CT has demonstrated very satisfying results in detecting melanoma metastases. We performed 18F-FDG PET/CT monitoring in metastatic melanoma patients undergoing ipilimumab therapy during treatment. Aim of our study was to evaluate the predictive role of 18F-FDG PET/CT performed after two cycles of ipilimumab in final response evaluation to therapy.

26 patients suffering from unresectable metastatic melanoma, scheduled for ipilimumab treatment underwent PET/CT scanning before the onset of therapy (baseline scan), after two cycles, and after the end of the four-cycle treatment. Patient response evaluation to treatment was based on the European Organization for Research and Treatment of Cancer (EORTC) 1999 criteria. Moreover, correlation analysis was performed between the changes in the number of melanoma lesions detected with PET/CT and the changes in lesions’ mean SUV taking place during the course of treatment. Results were considered significant for p<0.05.

After the end of treatment, 19 patients were characterized as having progressive metabolic disease (PMD), five patients as stable metabolic disease (SMD) and two patients showed partial metabolic response (PMR). However, three patients were falsely classified in the SMD, PMR and complete metabolic response (CMR) groups respectively, since they developed brain metastases, undetectable by PET/CT (PMD patient). PET/CT performed after two ipilimumab cycles predicted final treatment response in 14/19 PMD patients, in 5/5 SMD patients and in 0/2 PMR patients. Correlation analysis revealed significant correlation between changes in the number of melanoma lesions detected and changes in lesions’ mean SUVs during the course of treatment.

According to these preliminary results, 18F-FDG PET/CT after two cycles of ipilimumab is highly predictive of the final treatment outcome in PMD and SMD patients. However, its predictive results are rather poor in patients demonstrating partial disease remission.

This is the first study regarding treatment response evaluation to ipilimumab in metastatic melanoma patients, by means of 18F-FDG PET/CT, involving baseline, during therapy and after therapy completion examinations.

Sachpekidis, C, Haberkorn, U, Larribere, L, Dimitrakopoulou, G, Dimitrakopoulou-Strauss, A, Hassel, J, 18F-FDG PET/CT Performance in Treatment Response Evaluation in Metastatic Melanoma Patients under Ipilimumab.  Radiological Society of North America 2014 Scientific Assembly and Annual Meeting, - ,Chicago IL. http://archive.rsna.org/2014/14007127.html