Abstract
FOLFIRINOX chemotherapy is recommended as first-line treatment for metastatic pancreatic ductal adenocarcinoma (mPDAC). While its efficacy has been well documented in clinical trials, the responses observed have been predominantly partial. To date, only rare cases of complete response (CR) assessed by CT scan have been reported in the literature.
We present a case of sustained metabolic CR over 23 months assessed by LAFOV FDG-PET/CT in a 56-year-old male patient with poorly differentiated mPDAC treated with FOLFIRINOX.
This case highlights the emerging role of latest generation of digital FDG-PET/CT in assessing the therapeutic efficacy of systemic treatments for solid cancers.
Introduction
Pancreatic ductal adenocarcinoma (PDAC) accounts for approximately 500,000 new cases worldwide and is the 7th leading cause of cancer-related death in both men and women. The prognosis for PDAC remains extremely poor, with only 50% of patients surviving beyond 4 months and a 5-year survival rate of less than 10 % for metastatic disease ().
FOLFIRINOX (oxaliplatin, irinotecan, fluorouracil, and leucovorin) chemotherapy is recommended as a first-line treatment for metastatic pancreatic ductal adenocarcinoma (mPDAC) (). The randomized phase III PRODIGE trial showed that FOLFIRINOX significantly improved both median progression-free survival (6.4 vs. 3.3 months; p < 0.001) and overall survival (11.1 vs. 6.8 months; p < 0.001) compared to gemcitabine in patients with mPDAC. However, of the 54 responding patients in the FOLFIRINOX arm (n = 171), only one (0.6%) achieved a complete response (CR) ().
18F-Fluorodeoxyglucose positron emission tomography/computed tomography (FDG-PET/CT) is an accurate tool for the initial staging of PDAC, particularly for the detection of distant metastases. In addition, FDG-PET/CT is emerging as a useful approach and valuable method for the therapeutic assessment of systemic treatments in metastatic gastrointestinal cancers ().
Case Description
We report the case of a 56-year-old man with no prior medical history who was diagnosed with poorly differentiated metastatic pancreatic ductal adenocarcinoma (mPDAC). At diagnosis, the patient was in good general condition (ECOG performance status = 0), with no reported symptoms or abnormal clinical findings. Immunohistochemistry showed positivity for MMR proteins and HER2 negativity, while molecular analysis revealed microsatellite stable (MSS) status and a KRAS mutation, with no BRAF or BRCA mutations. Initial staging with FDG-PET/CT revealed lymph node and bone metastases (Figures 1A, 2A–C, E–G).
Figure 1
Figure 2
According to current guidelines, first-line treatment with FOLFIRINOX was initiated administered at dose of: oxaliplatin 85 mg/m2; irinotecan 180 mg/m2; leucovorin 400 mg/m2; and fluorouracil 400 mg/m2 as a bolus, followed by 2,400 mg/m2 as a 46-h continuous infusion every 2 weeks. Oxaliplatin was discontinued from the 5th cycle onward due to grade 2 hepatic cytolysis associated with grade 1 peripheral neuropathy. Following improvement in liver function tests and stabilization of neuropathy, oxaliplatin was reintroduced at the 8th cycle with a 20% dose reduction. However, it was permanently discontinued at the 10th cycle due to recurrence of hepatic cytolysis and peripheral neuropathy. Neuropathy subsequently remained stable at grade 1, and hepatic cytolysis completely resolved. Irinotecan was omitted at the 26th cycle due to esophagitis, and its dose was subsequently reduced by 17% for treatment continuation. Other adverse events were mainly gastrointestinal, consisting of nausea and vomiting, particularly at treatment initiation.
Follow-up FDG-PET/CT demonstrated a complete metabolic response (CMR) of the target lesions according to PERCIST criteria (Figures 1B, 2B–D, F–H). This response was correlated with a marked decrease in CA 19-9 levels, from more than 75,000 U/mL to within the normal range (Figure 3). Remission has been maintained for more than 23 months. The patient has remained in excellent general condition with an ECOG performance status of 0, continuing all usual daily activities. The baseline examination was performed using a conventional digital PET/CT without iodinated contrast enhancement, whereas response assessment was conducted using a long axial field-of-view (LAFOV) PET/CT with contrast-enhanced CT acquired during the portal venous phase.
Figure 3
Discussion
Platinum-based chemotherapy has been associated with improved overall survival in patients with pancreatic adenocarcinoma harboring germline BRCA1 or BRCA2 mutations (–). This was not the case for our patient, in whom no BRCA mutation was identified. Moreover, the detected KRAS mutation is not known to confer specific sensitivity to FOLFIRINOX or FOLFIRI according to available data (). Historically, gemcitabine monotherapy was the standard treatment for unresectable or recurrent disease (). Subsequently, phase III trials demonstrated the superiority of FOLFIRINOX and gemcitabine plus nab-paclitaxel over gemcitabine alone (, ).
To our knowledge, this represents one of the rare cases of CMR observed on FDG-PET/CT in a patient with mPDAC treated with FOLFIRINOX. To date, only four cases of complete response assessed by CT have been reported; among them, one patient had a FDG-PET/CT demonstrating a CMR (–).
Therapeutic assessment was performed using a latest-generation LAFOV PET system, approximately ten-fold more sensitive compared with the digital PET system used at baseline, thereby strengthening the validity of this complete response. Although two different imaging systems were used, the sequence of their use limits the potential impact of this methodological heterogeneity. The conventional digital PET performed at diagnosis, being less sensitive, may theoretically have failed to detect very small additional lesions; however, this would not have altered the already metastatic stage of the disease. Conversely, the LAFOV PET/CT used for therapeutic evaluation provides an excellent negative predictive value. Therefore, the demonstration of a CMR with this system strongly suggests that it would also have been observed with a conventional PET system. Furthermore, iodinated contrast enhancement does not influence metabolic response assessment. The literature indicates that CMR assessed by functional imaging often precedes morphological response in metastatic gastrointestinal cancers (, ). A literature review of previously published cases of complete response in mPDAC treated with FOLFIRINOX is summarized in Table 1 (–).
Table 1
| Ref. | Age/sex | Metastatic sites | Differentiation | Molecular profile | Chemotherapy | Type of CR | Initial clinical signs | Toxicities/ adaptations | Initial CA 19-9 | CA 19-9 at CR | Imaging | CR duration |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Our case | 56/M | Lymph nodes, bone | Poorly differentiated | MMR positivity and HER2 negativity; MSS and KRAS mutation; no BRAF or BRCA mutations | FOLFIRINOX → FOLFIRI | Radiological CR | General condition alteration, PS 0–1 | Neuropathy → oxaliplatin discontinued; Esophagitis → irinotecan dose reduction | 7,5000 U/mL | Normalized | PET-CT | 23 months |
| Shelemey 2020 (PMID: 34031062) | 59/F | Liver | Moderately differentiated | MSI-stable; CCND1 amplification; KRAS (G12D) and TP53 (G245S) mutations; BRCA1/2–, PALB2– | FOLFIRINOX → FOLFIRI | Radiological CR | Pain, nausea, sweating; PS 1 | Neuropathy → oxaliplatin discontinued | ↑ 14514 U/mL; peak at 35,170 U/mL | Normalized | CT/MRI | >4 years |
| Tsujie 2020 (PMID: 32698268) | 46/F | Distant lymph nodes | ND | BRCA1/2 negative | FOLFIRINOX → FOLFIRI | Histological and radiological CR | Obstructive jaundice | Neuropathy → oxaliplatin discontinued | ↑ 71795.1 U/mL | Normalized | CT/PET-CT | ≥4 years |
| Nikolaou 2015 (PMID: 26090249) | 51/M | Post-surgery: lymph nodes, liver, lungs | ND | ND | FOLFIRINOX → FOLFIRI | Radiological CR | Abdominal pain; jaundice; weight loss; PS 0 | Neuropathy → oxaliplatin discontinued; Hematologic toxicity; Digestive toxicity with steatohepatitis | ↑ 12000 U/mL | Normalized | CT | ≥3 years |
| Yildirim 2023 (PMID: 36729128) | 42/F | Liver | ND | BRCA2 mutated | FOLFIRINOX | Radiological CR | ND | ND | ND | ND | CT | >5 years |
Summary of previously reported cases of complete response in mPDAC treated with FOLFIRINOX.
CR, complete response; MMR, mismatch repair proteins; HER2: human epidermal growth factor receptor 2; MSS: microsatellite stable; MSI: microsatellite instability; PS: performance status; CT: computed tomography; MRI: magnetic resonance imaging; PET-CT: positron emission tomography-computed tomography; ND: Not described; CA 19-9: carbohydrate antigen 19-9; BRCA1/2: breast cancer gene ½; PALB2, partner and localizer of BRCA2; CCND1: cyclin D1 gene; TP53: tumor protein p53 gene.
Conclusion
We report a case of complete response of a metastatic PDAC on FDG-PET/CT using a more sensitive LAFOV system, highlighting the potential of FDG-PET/CT for therapeutic assessment of solid cancers in future clinical trials, particularly with these highly sensitive innovative systems.
Statements
Data availability statement
The original contributions presented in the study are included in the article/supplementary material, further inquiries can be directed to the corresponding author.
Ethics statement
Written informed consent was obtained from the individual(s) for the publication of any potentially identifiable images or data included in this article.
Author contributions
RA: Writing – original draft, Conceptualization, Writing – review & editing. JD: Writing – original draft, Writing – review & editing, Conceptualization. J-pM: Writing – original draft, Conceptualization, Writing – review & editing. P-YS: Conceptualization, Writing – original draft, Writing – review & editing.
Funding
The author(s) declared that financial support was not received for this work and/or its publication.
Conflict of interest
The author(s) declared that this work was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.
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The author(s) declared that generative AI was not used in the creation of this manuscript.
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Abbreviations
PDAC, pancreatic ductal adenocarcinoma; mPDAC, metastatic pancreatic ductal adenocarcinoma; FOLFIRINOX, combination chemotherapy regimen consisting of 5-fluorouracil, leucovorin (folinic acid), irinotecan, and oxaliplatin; FOLFIRI, combination chemotherapy regimen consisting of 5-fluorouracil, leucovorin (folinic acid), and irinotecan; CR, complete response; CMR, complete metabolic response; FDG-PET/CT, 18F-fluorodeoxyglucose positron emission tomography/computed tomography; LAFOV, long axial field-of-view (PET system); MMR, mismatch repair (proteins/system); HER2, human epidermal growth factor receptor 2; MSS, microsatellite stable; MSI, microsatellite instability; KRAS, Kirsten rat sarcoma viral oncogene homolog; BRCA1/2, breast cancer susceptibility gene 1 and 2; PALB2, partner and localizer of BRCA2; CCND1, cyclin D1 gene; TP53, tumor protein p53 gene; CA 19-9, carbohydrate antigen 19-9; PS, performance status; ECOG, Eastern cooperative oncology group; CT, computed tomography; MRI, magnetic resonance imaging; PERCIST, PET response criteria in solid tumors.
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Summary
Keywords
Complete response, FDG-PET/CT, FOLFIRINOX, LAFOV, mPDAC
Citation
Abgral R, Dzuko Kamga J, Metges J and Salaun P-Y (2026) Case Report: long complete metabolic response assessed by LAFOV FDG-PET/CT to FOLFIRINOX in first-line treatment of metastatic low-differentiated pancreatic carcinoma. Front. Med. 13:1788442. doi: 10.3389/fmed.2026.1788442
Received
15 January 2026
Revised
20 February 2026
Accepted
27 February 2026
Published
18 March 2026
Volume
13 - 2026
Edited by
Romina Grazia Giancipoli, Agostino Gemelli University Polyclinic (IRCCS), Italy
Reviewed by
Carmelo Caldarella, Fondazione Policlinico Universitario A. Gemelli IRCCS, Italy
Susovan Jana, National Institute of Mental Health (NIH), United States
Updates
Copyright
© 2026 Abgral, Dzuko Kamga, Metges and Salaun.
This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
*Correspondence: Jacques Dzuko Kamga, jacqueskamga10@gmail.com
Disclaimer
All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article or claim that may be made by its manufacturer is not guaranteed or endorsed by the publisher.