Malignancy Rate of Indeterminate Findings on FDG-PET/CT in Cutaneous Melanoma Patients

Melanin-targeted [18F]-PFPN PET imaging for prognosticating patients with melanoma

PURPOSE

Positron emission tomography (PET) using [18F]-PFPN, a melanin-targeted imaging tracer, has excellent diagnostic performance in patients with melanoma. This study aimed to investigate its value in prognostication and determine predictors of progression-free survival (PFS) and overall survival (OS).

METHODS

We reviewed melanoma patients who underwent [18F]-PFPN and [18F]-FDG PET from February 2021 to July 2022. Clinical characteristics, follow-up data, and the following [18F]-PFPN PET parameters were recorded: maximum standardized uptake value (SUVmax), whole-body melanotic tumoral volume (WBMTV), and whole-body total lesion melanin (WBTLM). Receiver operating characteristic (ROC), Kaplan-Meier and Cox regression analyses were performed.

RESULTS

Seventy-six patients (47 men and 29 women; mean age, 57.99 ± 10.72 years) were included for analysis. Median follow-up was 12.0 months (range: 1-22 months). Eighteen patients died and 38 experienced progression. Median OS was 17.60 months (95% confidence interval, 15.89-19.31). In the ROC analysis, [18F]-PFPN PET parameters were superior to those of [18F]-FDG PET in prognosticating death and disease progression. PFS and OS were significantly better in patients with lower SUVmax, WBMTV, and WBTLM on [18F]-PFPN PET (log-rank, P < 0.05). In the univariate analyses, distant metastasis, SUVmax, WBMTV, and WBTLM were significantly associated with cumulative incidence of PFS and OS (P < 0.05). In the multivariate analysis, SUVmax was an independent predictor of PFS and OS.

CONCLUSIONS

[18F]-PFPN PET has a role in prognostication of melanoma patients. Patients with higher [18F]-PFPN SUVmax have worse prognosis.

CLINICAL TRIAL REGISTRATION

ClinicalTrials.gov, NCT05645484. Registered 9 December, 2022, https://clinicaltrials.gov/ct2/show/NCT05645484?cond=The+Prognostic+Value+of+18F-PFPN+PET+Imaging+in+Patients+With+Malignant+Melanoma&draw=2&rank=1.

Sex-Related Differences in Metastatic Melanoma Patients Treated with Immune Checkpoint Inhibition

Objectives: We aimed to investigate sex-related differences in patients with advanced melanoma treated with ICI by linking the assessment of inflammatory response in peripheral blood, onset of immune-related adverse events IRAEs during therapy and treatment response in short- and long-term. Methods: For the purpose of this single-center retrospective study metastatic melanoma patients treated with ICI were included. Baseline patient characteristics, blood sample tests and the onset of immune-related adverse events IRAEs were documented based on clinical records. The short-term treatment response was assessed with 18F-2-Fluor-2-desoxy-D-glucose Positron Emission Tomography/Computed Tomography FDG-PET/CT scans performed six months after initiation of ICI. The overall survival OS and progression-free survival PFS were used as endpoints to assess the long-term response to immunotherapy. Results: In total, 103 patients with advanced melanoma (mean age 68 ± 13.83 years) were included, 29 women (mean age 60.41 ± 14.57 years) and 74 men (mean age 65.66 ± 13.34 years). The primary tumor was located on a lower extremity in one out of three women and on the head/neck in one out of three men (p < 0.001). While the superficial spreading (41%) and nodular (36%) melanoma subtypes represented together 77% of the cases in male population, women showed a more heterogenous distribution of melanoma subtypes with the superficial spreading (35%), nodular (23%), acral lentiginous (19%) and mucosal (12%) melanoma subtypes being most frequent in female population (p < 0.001). Most differences between women and men with regards to inflammatory parameters were observed six months after initiation of ICI with a higher median NLR (p = 0.038), lower counts of lymphocytes (p = 0.004) and thrombocytes (p = 0.089) in addition to lower counts of erythrocytes (p < 0.001) and monocytes (p < 0.001) in women towards men. IRAEs were more frequent in women towards men (p = 0.013). Women were more likely to display endocrinological IRAEs, such as thyroiditis being the most frequent adverse event in women. Interestingly IRAEs of the gastrointestinal tract were the most frequent ones in men. Finally, men with advanced melanoma showed a significantly better response to immunotherapy in short- (p = 0.015) and long-term (OS p = 0.015 and PFS p < 0.001) than women. In fact, every fourth man died during the course of the disease, while every second woman did not survive. (p = 0.001). Conclusion: Men with advanced melanoma showed a significantly better response to immunotherapy in short- and long-term than women. Higher immune activation in peripheral blood before and after initiation ICI might be linked to favorable treatment response during and after ICI in favor of men and decoupled from the onset of IRAEs. Given the significantly higher immunotoxicity and worse outcome experienced by women compared to men the use of ICI should be chosen carefully in women with advanced melanoma.