Vol.:(0123456789) 1 3 Annals of Nuclear Medicine https://doi.org/10.1007/s12149-018-01323-8 ORIGINAL ARTICLE Response evaluation with  18 F-FDG PET/CT in metastatic breast cancer patients treated with Palbociclib: frst experience in clinical practice Silvia Taralli 1  · Margherita Lorusso 1  · Valentina Scolozzi 1,2  · Valeria Masiello 3  · Fabio Marazzi 3  · Maria Lucia Calcagni 1,2 Received: 12 October 2018 / Accepted: 2 December 2018 © The Japanese Society of Nuclear Medicine 2018 Abstract Objective Palbociclib is a cyclin-dependent kinase 4/6 inhibitor recently approved for treatment in advanced or metastatic breast cancer (BC) patients. The use of 18 F-FDG PET/CT for chemo/endocrine therapy response assessment in BC patients is well reported in the literature, but no studies have evaluated its role for assessing Palbociclib efcacy in clinical practice. Our study aimed to evaluate the potential role of 18 F-FDG PET/CT in this setting. Methods In 12 metastatic BC patients (mean age = 62 ± 10 years) treated with Palbociclib plus endocrine therapy and who underwent a baseline and post-therapy 18 F-FDG PET/CT, we retrospectively compared the Metabolic Response Evaluation (MRE, based on PET/CT) to the Standard Response Evaluation (SRE, based on clinico-laboratory and morphological data); we also assessed the infuence of additional PET/CT information on the patients’ management. Results Compared to SRE, MRE increased the proportion of patients classifed with progressive disease from 25 to 50% and difered from SRE in 8/12 patients: 3/8 shifted from stable disease or undetermined response to metabolic progression (more unfavorable category), 4/8 from stable disease to partial or complete metabolic response, and 1/8 from partial response to complete metabolic response (more favorable category). Additional PET/CT information led to a change in patients’ management in 3/12 (25%) patients. Conclusion In BC patients treated with Palbociclib, additional 18 F-FDG PET/CT information seems clinically useful, with respect to personalized management, to early intercept patients who should discontinue Palbociclib because of progressive disease and to select patients requiring a strict monitoring of additional metabolic fndings. Further studies are needed to confrm these preliminary results. Keywords 18 F-FDG PET/CT · Breast cancer · Palbociclib · Response assessment Introduction Breast cancer (BC) is the most common malignancy in women; it is a heterogeneous disease with diferent clini- cal and molecular characteristics. About 80% of all breast cancers are estrogen receptor-positive (ER+), and so most patients beneft from hormonal treatment [1]. Nevertheless, resistance to hormonal therapy often occurs, requiring change to a diferent therapy to evade resistance mecha- nisms. The molecular signaling pathways causing endocrine resistance development have been discovered and diferent so-called “targeted therapies” have been introduced to pre- vent or reverse resistance [2]. Targeted therapies or mecha- nism-based drugs are directed to specifc abnormalities that drive the malignant phenotype and have taken place in the last 2 decades. These agents are predominantly cytostatic in nature; that is, they stop the growth of tumors rather than causing a signifcant tumor cell death. In the context of the emerging targeted therapies, Palbociclib has been recently approved in the United States and Europe as a frst-line treatment in association with letrozole in postmenopausal women with ER-positive and HER2-negative metastatic breast cancer [3–5]. Palbociclib is a selective inhibitor of cyclin-dependent kinases 4 and 6 (CDK 4/6) that prevents * Silvia Taralli silvia.taralli@hotmail.it 1 Nuclear Medicine Unit, Fondazione Policlinico Universitario Agostino Gemelli IRCCS, Largo Francesco Vito, 1, 00168 Rome, Italy 2 Nuclear Medicine Institute, Università Cattolica del Sacro Cuore, Rome, Italy 3 Radiation Oncology Unit, Fondazione Policlinico Universitario Agostino Gemelli IRCCS, Rome, Italy