Cutaneous Squamous Cell Carcinoma Subjected to Anti PD-1 Immunotherapy: Monitoring Response Through Serial PET/CT Scans with 18F-FDG

The Prognostic Role of [18F]FDG PET/CT in Patients with Advanced Cutaneous Squamous Cell Carcinoma Submitted to Cemiplimab Immunotherapy: A Single-Center Retrospective Study

Background: Baseline 2-deoxy-2[18F]fluoro-d-glucose ([18F]FDG) positron emission tomography (PET)-derived parameters and 12-week metabolic response were investigated as prognostic factors in advanced cutaneous squamous cell carcinoma (cSCC) submitted to cemiplimab immunotherapy. Materials and Methods: Clinical records of 25 cSCC patients receiving cemiplimab, submitted to [18F]FDG positron emission tomography/computed tomography (PET/CT) at baseline and after ∼12 weeks, were retrospectively reviewed. The Kaplan-Meier (KM) method was applied to analyze differences in event-free survival (EFS), and Cox regression analysis was employed to identify the prognostic factors. Results: At the 12-week PET/CT evaluation, 16 patients (64%) were classified as responders (complete or partial response) and 9 (36%) as nonresponders ("unconfirmed progressive metabolic disease") according to immune PET Response Criteria in Solid Tumors (iPERCIST). By KM analysis, baseline metabolic tumor volume (MTV) and total lesion glycolysis (TLG) significantly correlated with the EFS (p < 0.05). Furthermore, the KM analysis showed that the lack of metabolic response at 12 weeks was associated with meaningfully shorter EFS (7.2 ± 1 months in nonresponders vs. 20.3 ± 2.3 months in responders). In Cox multivariate analysis, metabolic response at 12 weeks remained the only predictor of the EFS (p < 0.05). Conclusions: Baseline tumor load (i.e., MTV and TLG) and metabolic response at 12 weeks may have a prognostic impact in cSCC patients treated with cemiplimab.

Cemiplimab for the Treatment of Advanced Cutaneous Squamous Cell Carcinoma: Appropriate Patient Selection and Perspectives

Five percent of patients with cutaneous squamous cell carcinoma develop locally advanced or metastatic disease that is not amenable to definitive surgical or radiation therapy. Cemiplimab, an antibody against programmed death receptor-1, was approved in the United States for the treatment of locally advanced and metastatic cutaneous squamous cell carcinoma in 2018. We performed a literature review on the use of cemiplimab in cutaneous squamous cell carcinoma, with an emphasis on efficacy, safety and tolerability, patient selection, and future directions. Embase and PubMed were searched for relevant terms, and 23 peer-reviewed journal articles presenting primary data on cemiplimab treatment in 5 or more subjects with cutaneous squamous cell carcinoma were included and summarized. Objective response rates in locally advanced and metastatic disease ranged from 42.9% to 50.8% in Phase I/II clinical trials and 32-77% (median 58%) in post-approval observational studies. Phase II trials looking at neoadjuvant use also had favorable response rates. Real-world studies demonstrated cemiplimab efficacy in periorbital tumors, tumors with large caliber perineural invasion, and tumors in solid organ transplant recipients. Cemiplimab was safe and well-tolerated in most patients. While side effects such as fatigue, diarrhea, pruritus, and rash were fairly common, only 9.8% of adverse events required cessation of therapy in phase II trials. Severe adverse events were primarily immune-mediated, including pneumonitis, myocarditis, myositis, and autoimmune hepatitis; the risk of treatment-related death was 3% in clinical trials. Further research on cemiplimab therapy in cutaneous squamous cell carcinoma is needed, and trials are now underway to obtain Phase IV long-term real-world data, further data on adjuvant and neoadjuvant use, and additional data in special populations such as stem cell and solid organ transplant recipients.

The Role and Potential of 18F-FDG PET/CT in Malignant Melanoma: Prognostication, Monitoring Response to Targeted and Immunotherapy, and Radiomics

Novel therapeutic approaches, consisting of immune check-point inhibitors (ICIs) and molecularly targeted therapy, have thoroughly changed the clinical management of malignant melanoma (MM), the most frequent and deadly skin cancer. Since only 30–40% of MM patients respond to ICIs, imaging biomarkers suitable for the pre-therapeutic stratification and response assessment are warmly welcome. In this scenario, positron emission computed tomography (PET/CT) with 18F-fluorodeoxyglucose (18F-FDG) has been successfully utilized for advanced MM staging and therapy response evaluation. Furthermore, several PET-derived parameters (SUVmax, MTV, TLG) were particularly impactful for the prognostic evaluation of patients submitted to targeted and immunotherapy. In this review, we performed a web-based and desktop research on the clinical applications of 18F-FDG PET/CT in MM, with a particular emphasis on the various metabolic criteria developed for interpreting PET/CT scan in patients undergoing immunotherapy or targeted therapy or a combination of both. Furthermore, the emerging role of radiomics, a quantitative approach to medical imaging applying analysis methodology derived by the field of artificial intelligence, was examined in the peculiar context, putting a particular emphasis on the potential of this discipline to support clinicians in the delicate process of building patient-tailored pathways of care.