Response to Immune Checkpoint Inhibitor Therapy in Patients with Unresectable Recurrent Malignant Pleural Mesothelioma Shown by FDG-PET and CT

• Main Authors: Kazuhiro Kitajima, Mitsunari Maruyama, Hiroyuki Yokoyama, Toshiyuki Minami, Takashi Yokoi, Akifumi Nakamura, Masaki Hashimoto, Nobuyuki Kondo, Kozo Kuribayashi, Takashi Kijima, Seiki Hasegawa, Koichiro Yamakado
• Format: Article
• Language: English
• Published: MDPI AG 2021-03-01
• Series: Cancers
• Subjects: mesothelioma; immunotherapy; therapy response; survival; FDG; PET-CT
• Online Access: https://www.mdpi.com/2072-6694/13/5/1098

Background: To compare three FDG-PET criteria (EORTC, PERCIST, imPERCIST) with CT criteria (combined modified RECIST and RECIST 1.1) for response evaluation and prognosis prediction in patients with recurrent MPM treated with ICI monotherapy. Methods: Thirty MPM patients underwent FDG-PET/CT and contrast-enhanced CT at the baseline and during nivolumab therapy (median 10 cycles). Therapeutic response was evaluated according to EORTC, PERCIST, imPERCIST, and CT criteria. PFS and OS were examined using log-rank and Cox methods. Results: CMR/PMR/SMD/PMD numbered 5/3/4/18 for EORTC, 5/1/7/17 for PERCIST, and 5/3/9/13 for imPERCIST. With CT, CR/PR/SD/PD numbered 0/6/10/14. There was high concordance between EORTC and PERCIST (κ = 0.911), and PERCIST and imPERCIST (κ = 0.826), while that between EORTC and imPERCIST (κ = 0.746) was substantial, and between CT and the three PET criteria moderate (κ = 0.516–0.544). After median 14.9 months, 26 patients showed progression and nine died. According to both PET and CT findings, patients with no progression (CMR/PMR/SMD or CR/PR/SD) showed significantly longer PFS and somewhat longer OS than PMD and PD patients (EORTC <i>p</i> = 0.0004 and <i>p</i> = 0.055, respectively; PERCIST <i>p</i> = 0.0003 and <i>p</i> = 0.052; imPERCIST <i>p</i> < 0.0001 and <i>p</i> = 0.089; CT criteria <i>p</i> = 0.0015 and <i>p</i> = 0.056). Conclusions: Both FDG-PET and CT criteria are accurate for response evaluation of ICI therapy and prediction of MPM prognosis. In comparison with CT, all three FDG-PET/CT criteria judged a greater percentage of patients (16.7%) as CMR, while two (EORTC, PERCIST) judged a greater percentage (10–13.3%) as PMD. For predicting PFS, the three FDG-PET criteria were superior to the CT criteria, and imPERCIST demonstrated the highest rate of accurate prediction.