Comparison of FDG-PET/CT and CT for evaluation of tumor response to nivolumab plus ipilimumab combination therapy and prognosis prediction in patients with unresectable malignant pleural mesothelioma

Our plain-English summary of Comparison of FDG-PET/CT and CT for evaluation of tumor response to nivolumab plus ipilimumab combination therapy and prognosis prediction in patients with unresectable malignant pleural mesothelioma, by K. Kitajima, K. Kuribayashi, T. Minami, et al (Oncotarget, 2024).

The study

• Authors: K. Kitajima, K. Kuribayashi, T. Minami, H. Yokoyama, A. Nakamura, M. Hashimoto, T. Kijima, S. Hasegawa, H. Kaida, K. Yamakado
• Journal: Oncotarget
• Published: 2024;15:408-417
• Cited by: 5 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

Objectives: Results for malignant pleural mesothelioma (MPM) patients following first-line treatment with nivolumab plus ipilimumab obtained with immunotherapy-modified PERCIST (imPERCIST), shown by [18F]fluorodeoxyglucose positron emission tomography/computed tomography (FDG-PET/CT), and modified RECIST (mRECIST), shown by CT, were compared for response evaluation and prognosis prediction.

Results: imPERCIST indicated nine progressive metabolic disease (PMD), eight stable metabolic disease (SMD), four partial metabolic response (PMR), and five complete metabolic response (CMR) cases. mRECIST showed nine with progressive disease (PD), nine stable disease (SD), seven partial response (PR), and one complete response (CR). Although high concordance was noted (κ = 0.827), imPERCIST correctly judged a greater percentage with CMR (15.4%). Following a median 10.0 months, 15 patients showed progression and eight died from MPM. With both, progression-free survival (PFS) and overall survival (OS) were significantly longer in patients without progression (CMR/PMR/SMD, CR/PR/SD, respectively) as compared to PMD/PD patients (imPERCIST p < 0.0001 and p = 0.015, respectively; mRECIST p < 0.0001 and p = 0.015, respectively).

Methods: Twenty-six patients (23 males, 3 females; median 73.5 years) with histologically proven MPM and no curative surgery received nivolumab plus ipilimumab combination therapy. FDG-PET/CT and diagnostic CT scanning at the baseline, and after 2-4 cycles (2 in three, 3 in 17, 4 in six patients) were performed. Therapeutic response findings evaluated using imPERCIST and mRECIST were compared. PFS and OS analyses were done using log-rank and Cox methods.

Conclusion: For unresectable MPM patient examinations, FDG-PET and CT provide accurate findings for evaluating tumor response and also prognosis prediction following first-line nivolumab plus ipilimumab immunotherapy (approximately three cycles).

In plain English

This retrospective study from Hyogo Medical University in Japan compared two scan-based ways of judging how malignant pleural mesothelioma responded to first-line nivolumab plus ipilimumab immunotherapy. One used FDG-PET/CT with imPERCIST criteria; the other used CT with mRECIST criteria. It included 26 patients (23 men, 3 women; median age 73.5) who could not have surgery, scanned before treatment and after about three cycles. The two methods agreed closely (kappa 0.827). Four patients (15.4%) judged to have a complete metabolic response on FDG-PET/CT were not judged complete responders on CT. During follow-up, 15 of 26 patients progressed and eight died from mesothelioma. With either method, patients without progression on the scan had significantly longer progression-free survival (p less than 0.0001) and overall survival (p = 0.015) than patients with progression. Differences between responders and non-responders were not statistically significant. The authors concluded that both methods were useful and that FDG-PET/CT showed slight superiority. They noted that the study was retrospective, at a single center, and small.

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: Retrospective single-center study comparing two imaging response criteria (imPERCIST on FDG-PET/CT and mRECIST on CT) in the same patients
• Who was studied: 26 patients with histologically diagnosed malignant pleural mesothelioma who were not surgery candidates (23 males, 3 females; median age 73.5, range 63 to 85), referred to the authors' institution in Hyogo, Japan, between September 2021 and December 2023. 16 had epithelioid and 10 had non-epithelioid histology.
• Exposure: Not an asbestos exposure study. The exposure studied was first-line treatment with nivolumab 3 mg/kg every two weeks plus ipilimumab 1 mg/kg every six weeks. Patients had FDG-PET/CT and diagnostic CT at baseline and after 2 to 4 cycles (2 cycles in three patients, 3 in 17, 4 in six).
• Main results:
  • Whole cohort, FDG-PET/CT (imPERCIST): progressive metabolic disease in 9, stable metabolic disease in 8, partial metabolic response in 4, complete metabolic response in 5 of 26 patients.
  • Whole cohort, CT (mRECIST): progressive disease in 9 (34.6%), stable disease in 9 (34.6%), partial response in 7 (26.9%), complete response in 1 (3.8%).
  • The two methods showed high agreement (kappa 0.827). Four patients (15.4%) were classified as complete metabolic response by imPERCIST but not by CT (mRECIST).
  • By histology: in the epithelioid group (n = 16), agreement was kappa 0.805 and imPERCIST showed a greater percentage with complete metabolic response (12.5%). In the non-epithelioid group (n = 10), agreement was kappa 0.828 and the figure was 20.0%.
  • 15 (57.7%) of the 26 patients developed progressive disease, at a median of 8.9 months (range 1.9 to 26.9 months).
  • Patients without progression on either method had significantly longer progression-free survival than patients with progression (imPERCIST p less than 0.0001; mRECIST p less than 0.0001).
  • After a median of 10.0 months (range 2.4 to 27.0), 8 (30.8%) patients died from mesothelioma. Patients without progression had significantly longer overall survival than those with progression on both methods (imPERCIST p = 0.015; mRECIST p = 0.015).
  • Responders had longer progression-free survival than non-responders, but the difference was not statistically significant (imPERCIST p = 0.12; mRECIST p = 0.21). The same was true for overall survival (imPERCIST p = 0.14; mRECIST p = 0.16).
  • Treatment-related adverse events occurred in 4 (15.4%) of the 26 patients: enteritis in two, dermatitis in one, encephalitis in one.
• The authors' conclusion: The authors concluded that both FDG-PET/CT (imPERCIST) and CT (mRECIST) were useful for evaluating tumor response to first-line nivolumab plus ipilimumab (about three cycles) and for predicting progression in unresectable malignant pleural mesothelioma. They stated that the FDG-PET/CT criteria demonstrated a slight superiority.
• Limitations the authors state:
  • Retrospective design, single center, and small number of patients, making the findings difficult to generalize.
  • The authors stated that a larger prospective multicenter trial would be needed.

Topics

The National Library of Medicine indexes this study under subjects our site covers: Lung cancer, Mesothelioma.

Medical terms in this study, explained in our Lexicon: Nivolumab (Opdivo), Ipilimumab (Yervoy), Prognosis, Unresectable, Pleural Mesothelioma, Immunotherapy, Modified RECIST (mRECIST), Progression-Free Survival.

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