Visual Abstract
Abstract
The fibroblast activation protein (FAP) is highly expressed on carcinoma-associated fibroblasts in the stroma of pancreatic cancer and thus is a promising target for imaging and therapy. Preliminary data on PET imaging with radiolabeled FAP inhibitors (FAPIs) demonstrate superior tumor detection. Here we assess the accuracy of FAP-directed PET in patients with pancreatic cancer. Methods: Of 64 patients with suspected or proven pancreatic cancer, 62 (97%) were included in the data analysis of the 68Ga-FAPI PET observational trial (NCT04571086). All of these patients underwent contrast-enhanced CT, and 38 patients additionally underwent 18F-FDG PET. The primary study endpoint was the association of 68Ga-FAPI PET uptake intensity and histopathologic FAP expression. Secondary endpoints were detection rate, diagnostic performance, interreader reproducibility, and change in management. Datasets were interpreted by 2 masked readers. Results: The primary endpoint was met: The association between 68Ga-FAPI SUVmax and histopathologic FAP expression was significant (Spearman r, 0.48; P = 0.04). For histopathology-validated lesions, 68Ga-FAPI PET showed high sensitivity and positive predictive values (PPVs) on per-patient (sensitivity, 100%; PPV, 96.3%) and per-region (sensitivity, 100%; PPV, 97.0%) bases. In a head-to-head comparison versus 18F-FDG or contrast-enhanced CT, 68Ga-FAPI detected more tumor on a per-lesion (84.7% vs. 46.5% vs. 52.9%), per-patient (97.4% vs. 73.7% vs. 92.1%), or per-region (32.6% vs. 18.8% vs. 23.7%) basis, respectively. 68Ga-FAPI PET readers showed substantial overall agreement on the basis of the Fleiss κ: primary κ, 0.77 (range, 0.66–0.88). Minor and major changes in clinical management occurred in 5 patients (8.4%) after 68Ga-FAPI PET. Conclusion: We confirmed an association of 68Ga-FAPI PET SUVmax and histopathologic FAP expression in pancreatic cancer patients. Additionally, we found high detection rate and diagnostic accuracy, superior to those of 18F-FDG PET/CT. 68Ga-FAPI might become a powerful diagnostic tool for pancreatic cancer work-up.
Pancreatic ductal adenocarcinoma (PDAC) is a frequent solid malignancy associated with extremely poor survival (1). Because of late detection, PDAC is often diagnosed in advanced or metastasized stages, which emphasizes the necessity of accurate imaging methods for suspected lesions. Emerging data suggest a prominent role for the tumor microenvironment and carcinoma-associated fibroblasts supporting the aggressiveness and high therapeutic resistance of these tumors (2). As such, carcinoma-associated fibroblasts influence tumor cells by producing signaling and metabolic mediators and can promote tumor angiogenesis, migration, and proliferation (3,4). The fibroblast activation protein (FAP) is highly expressed in carcinoma-associated fibroblasts in the stroma of PDAC and numerous other tumor entities (5) and activated fibroblasts in nonmalignant stroma tissue to promote wound healing, but it is absent in normal adult tissues (6–9). A metaanalysis of 15 studies showed that FAP overexpression in solid tumors, including PDAC, is associated with a poor outcome and is distinctively seen in tumor tissue compared with normal tissue (6,7).
In 2018, novel FAP-targeted radiotracers were introduced for diagnostic and therapeutic purposes and showed promising diagnostic value for multiple entities, including PDAC (8,9). A more recent retrospective analysis of Röhrich et al. showed that 68Ga-labeled FAP inhibitor (68Ga-FAPI) PET changed disease stages of 10 of 19 recruited PDAC patients compared with standard-of-care imaging (10). Further changes in oncologic management occurred in 7 patients (10). In addition, FAP radioligands can be labeled with β-emitting radionuclides (e.g., 177Lu and 90Y) for FAP-targeted radioligand therapy (8,11,12), a promising treatment option for patients with metastases.
We initiated a prospective, single-center observation trial (68Ga-FAPI PET trial) to investigate the association of histopathologic FAP expression and 68Ga-FAPI PET tracer uptake intensity in various tumor entities (9). We further aimed to analyze 68Ga-FAPI PET sensitivity, specificity, and positive predictive value (PPV) as well as the impact on management of this new methodology. Here we report data on the PDAC cohort of the 68Ga-FAPI PET observational trial.
METHODS
Study Design and Patients
The flow of patients is illustrated in Figure 1. This study was a subgroup analysis of the ongoing 68Ga-FAPI PET observational trial. Until November 2020, adult patients who had proven or suspected PDAC and who underwent clinical 68Ga-FAPI PET/CT were offered consent for an observational trial conducted at University Hospital Essen (NCT04571086). Before enrollment, patients gave written consent to undergo 68Ga-FAPI PET/CT for a clinical indication. Patients were enrolled irrespective of prior conventional imaging or treatment. The detailed study protocol has been described previously (13).
Enrollment flowchart.
In short, patients who were scheduled for 68Ga-FAPI PET/CT for staging or restaging of PDAC as part of the clinical routine and who were 18 y old or older were enrolled. The primary endpoint was the association between 68Ga-FAPI uptake intensity and histopathologic FAP expression. The primary endpoint was met if PET uptake and tissue FAP expression showed a significant Spearman correlation (ordinal data). Secondary endpoints were detection rate and PPV on per-patient and per-region bases as well as sensitivity and specificity confirmed by histopathology. Additionally, the impact on management and interreader reproducibility were analyzed.
The study was initiated, planned, conducted, analyzed, and published by the investigators. No financial support was received from commercial entities. All reported investigations were conducted in accordance with the Declaration of Helsinki and with national regulations. This observational trial was registered on ClinicalTrials.gov (NCT04571086) and was approved by the local ethics committee (permit numbers 19-8991-BO and 20-9485-BO). Patients gave written informed consent for inclusion in the observational trial.
Imaging
Clinical PET scans were performed in the craniocaudal direction on Biograph mCT or Biograph mCT VISION scanners (Siemens Healthineers). All 68Ga–FAPI-46 PET and 18F-FDG PET scans were performed as PET/CT (including low-dose CT). The mean ± SD injected activity of 68Ga-FAPI was 142 ± 39 MBq, and that of 18F-FDG was 221 ± 107 MBq. 68Ga–FAPI-46 PET/CT images were acquired approximately 15 min (14.7 ± 7.3 min) after injection, and 18F-FDG PET/CT images were acquired 60 min (66.4 ± 17.5 min) after injection. Diagnostic contrast-enhanced CT (Ce-CT) with a standard protocol (80–100 mA, 120 kV) and iodinated contrast material (arterial and venous abdominal contrast phases) or 18F-FDG PET/CT was included if performed within 4 wk of 68Ga-FAPI PET/CT. Patients were monitored for adverse events until the end of the examination time and for at least 1 h after 68Ga–FAPI-46 injection.
For each scan, the number of lesions per region and per patient and the size of the lesion with the highest tracer uptake per region were recorded. Any focal tracer uptake higher than the surrounding background and not associated with physiologic uptake was considered suggestive of malignancy. SUVs (e.g., SUVmax, SUVpeak) of tumor lesions were measured with a region-growing algorithm with a threshold of 40% of the maximal uptake (Syngo.via software; Siemens Healthcare) for the lesion with the highest tracer uptake in the respective cancer site (primary lesion; local nodal, distant nodal, liver, peritoneal, lung, and bone metastases; and other [e.g., organ, skin, or soft-tissue] metastasis). SUVpeak was measured using Syngo.via in accordance with the PERCIST definition as the average SUV in the hottest 1-cm3 sphere within the volume of interest. Images were reported independently by 2 experienced, masked nuclear medicine physicians (PET/CT) or radiologists (Ce-CT) for each of the respective modalities (experience: >500 68Ga-FAPI PET/CT, >1,000 18F-FDG PET/CT, and >2,000 Ce-CT scans). Readers had to adhere to a 4-wk pause before reading other modalities. Readers were unaware of previous pancreatectomy. Divergent findings were discussed and reported in a separate consensus session between readers.
Lesion Validation
All patients were followed up for histopathologic analysis and, if possible, respective FAP immunohistochemistry (IHC). Lesions were included if 68Ga-FAPI PET findings could be directly validated with histopathologically proven lesions within 3 mo of examination. Alternatively, every available immunohistopathologic specimen was correlated with the highest SUVmax and SUVpeak in the respective regions for specimens acquired within 3 mo of 68Ga-FAPI PET or any specimen available for FAP immunohistopathologic analysis. Validation was performed by the unmasked local investigators after review of images and reports in accordance with prespecified criteria of the study protocol. All patients were additionally followed up for conventional imaging (18F-FDG PET/CT, CT, and/or MRI) or serum tumor marker CA19-9 after local/focal therapy (e.g., surgery or radiotherapy) acquired as part of the clinical routine. A composite reference standard was used as a combination of histopathology, imaging, and CA19-9 follow-up after local/focal therapy.
Immunohistochemistry
Biopsy and surgical specimens were stained with standard hematoxylin and eosin and FAP IHC stains and evaluated as previously described (13,14). In short, staining results were evaluated visually by an experienced pathologist who was unaware of imaging findings. Staining results were scored on a 4-point scoring system, where negative = 0, 1%–10% FAP-positive cells = 1, 11%–50% FAP-positive cells = 2, and >50% FAP-positive cells = 3.
Survey Design
A change in management was measured by the completion of 2 questionnaires by referring physicians (13,15). The first questionnaire was required to assess the existing treatment plan for the patient without the information from 68Ga-FAPI PET. The second questionnaire inquired about intended management after receipt of the written clinical report and the 68Ga-FAPI PET images. After return of the second questionnaire, all other pending imaging findings were disclosed. Implementation of intended management was verified by patient file review or information provided by the referring physician. Intermodality changes were considered major changes (e.g., change from local to systemic therapy). Otherwise, intramodality changes (e.g., change of surgical route or change in systemic treatment) were regarded as minor changes (e.g., change from chemotherapy to immunotherapy or radioligand therapy).
Statistical Analysis
The primary endpoint was association between 68Ga-FAPI PET uptake intensity and histopathologic FAP expression. PET uptake and tissue FAP expression were compared by use of the Spearman correlation. In addition, uptake and expression data were compared descriptively for each score/uptake/expression range. Sensitivity, specificity, PPV, negative predictive value (NPV), and accuracy, on per-patient and per-region bases, of 68Ga-FAPI PET for the detection of tumor location confirmed with histopathology/biopsy or the composite reference standard were calculated and reported along with the corresponding 2-sided 95% CIs. The CIs were constructed using the Wilson score method. The detection rate was defined as the total number and percentage of positive PET/CT or Ce-CT scans identified by the imaging readers and calculated as the number of positive lesions/patients/regions divided by the number of all lesions/patients/numbers reported × 100. Uptake measurements of tumor regions were tested for statistical differences using a nonparametric Mann–Whitney U test. Interreader agreement was calculated with the Fleiss κ. All statistical analyses were performed using SSPS software (version 28.0; SPSS Inc.) or GraphPad Prism (version 9.1.1; GraphPad Software).
RESULTS
Patient Characteristics
Until November 2021, 64 patients with suspected or proven pancreatic cancer were enrolled at the University Hospital Essen; 63 of these patients received 68Ga-FAPI PET/CT (1 patient who received PET/MRI was excluded). Within 4 wk before or after 68Ga-FAPI PET/CT, 62 patients (98.4%) had Ce-CT and 38 patients (60.3%) had 18F-FDG PET/CT. The latter 38 patients underwent all 3 modalities within 4 wk of 68Ga-FAPI PET/CT. No patient had any therapeutic change/intervention in the time intervals between the 68Ga-FAPI PET/CT, 18F-FDG PET/CT, and Ce-CT scans. Table 1 shows detailed clinical characteristics of all patients. No examination-related adverse events were reported. Most patients (n = 61; 97%) had pancreatic cancer, mostly pancreatic ductal adenocarcinoma (n = 57; 93%) and rarely anaplastic (n = 2; 3%), mucinous (n = 1; 2%), and acinar cell (n = 1; 2%) carcinomas. Detailed numbers and types of tissue sampling are shown in Supplemental Table 3.
Characteristics of 63 Patients
Association Between 68Ga-FAPI PET Uptake Intensity and FAP Expression
Comparisons of 68Ga-FAPI uptake values and histopathologic FAP scores (n = 18) are depicted in Figure 2. A significant strong association between SUVpeak and immunohistochemical scores for samples acquired within 3 mo of PET/CT (n = 8) was observed (SUVpeak r, 0.73; P = 0.04), whereas SUVmax did not correlate with those samples (SUVmax Spearman r, 0.65; P = 0.09) (Fig. 2A). Correlations of the FAP score for any available specimen with the respective tumor regions showed a significant moderate relationship for SUVmax (Spearman r, 0.60; P < 0.01) (Fig. 2B). Details for uptake values for 68Ga-FAPI and 18F-FDG are shown in Supplemental Table 1.
Primary endpoint: association between 68Ga-FAPI PET uptake intensity and FAP IHC score. (A) Spearman r for 68Ga-FAPI SUVmax and SUVpeak by FAP IHC score of histopathology within 3 mo of 68Ga-FAPI PET. Correlation with SUVpeak (n = 8; SUVmax r, 0.65 [P = 0.09]; SUVpeak r, 0.73 [P = 0.04]) was moderate. (B) Significant moderate correlation for 68Ga-FAPI SUVmax and FAP IHC score of any sample (n = 18; SUVmax r, 0.60; P < 0.01). SUVpeak did not correlate with FAP IHC.
Diagnostic Performance
In total, 28 patients (44.4%) and 36 regions were validated by histopathology, and 58 patients (92.1%) and 225 regions were validated with the composite reference standard. The detailed diagnostic performance and CIs on per-patient and per-region bases are shown in Table 2. In patients with positive PET results and histopathologic validation, PPVs were 96.3% on a per-patient basis (n = 27) and 97.0% on a per-region basis (n = 33). In cases with histopathologic validation, sensitivity was 100% on per-patient and per-region bases (Table 2). The composite reference standard showed similar performance on per-patient (sensitivity, 100%; PPV, 94.6%) and per-region (sensitivity, 98.0%; PPV, 91.7%) bases. Regardless of the type of validation 68Ga-FAPI showed high diagnostic accuracy, for example, 96.4% by histopathologic validation on a per-patient basis (Table 2).
68Ga-FAPI PET Accuracy*
In the subgroup of patients with matched 68Ga-FAPI PET/CT and 18F-FDG PET/CT scans, accuracy was compared (n = 32) (Table 3). Generally, both tracers showed similar diagnostic performances, with partially higher sensitivity, NPV, and accuracy for 68Ga-FAPI PET/CT on per-patient and per-region bases. Of note, by histopathologic confirmation, sensitivity, specificity, PPV, NPV, and accuracy were 100% for 68Ga-FAPI and 18F-FDG on a per-patient basis; however, differences in sensitivity, NPV, and accuracy on a per-region basis (sensitivity, 100% vs. 86.7%; NPV, 100% vs. 50%; and accuracy, 100% vs. 88.2%) were noted because of a higher rate of negative findings for 18F-FDG (n = 2 for 68Ga-FAPI vs. n = 10 for 18F-FDG). The rate of false-positive results was higher for 68Ga-FAPI than for 18F-FDG (n = 5 for 68Ga-FAPI vs. n = 1 for 18F-FDG), resulting in lower specificity and PPV for 68Ga-FAPI on per-patient and per-region bases (Table 3).
68Ga-FAPI PET and 18F-FDG PET Accuracy for 32 Patients*
Detection Rate
The detection rates for 68Ga-FAPI PET/CT versus 18F-FDG PET/CT versus Ce-CT (n = 38) and 68Ga-FAPI PET.CT versus Ce-CT (n = 62) are summarized in Table 4. In the comparison of 68Ga-FAPI PET/CT, 18F-FDG PET/CT, and Ce-CT, overall, 346 lesions were detected by any modality, with the highest detection by 68Ga-FAPI PET/CT (293, 161, and 183, respectively; P = 0.0001) and with the higher detection on a per-region basis by 68Ga-FAPI PET/CT (99, 57, and 72 positive regions, respectively; P = 0.0001). Especially primary, liver, and peritoneal regions had more positive lesions on 68Ga-FAPI PET/CT. The lowest detection rate was observed for the lung region (2, 3, and 7 for 68Ga-FAPI PET/CT, 18F-FDG PET/CT, and Ce-CT, respectively). Figure 3 shows a case example of a recurrent tumor positive on 68Ga-FAPI PET/CT and Ce-CT but not on 18F-FDG PET/CT.
Comparison of Detection Rates for 68Ga-FAPI, 18F-FDG, and Ce-CT (n = 38)
Case presentation. Male patient with suspected recurrent pancreatic cancer. Ce-CT shows mass around superior mesenteric artery after pancreatectomy. 18F-FDG only shows discrete uptake of lesion (SUVmax, 3.8), whereas 68Ga-FAPI clearly visualizes recurrent tumor. Patient received adjuvant chemotherapy after 68Ga-FAPI. Patient denied recommended chemotherapy. Increase of CA19-9 levels (from 240 to 767 U/mL) and follow-up imaging 8 mo later validated progression of mesenteric mass as well as increased 18F-FDG uptake (SUVmax, 5.3). MIP = maximum-intensity projection.
Reproducibility
On a per-region basis, both masked readers showed an overall substantial agreement for all modalities, with the lowest overall agreement for Ce-CT (68Ga-FAPI PET/CT κ, 0.77; 18F-FDG PET/CT κ, 0.78; and Ce-CT κ, 0.70) (Table 5). Fleiss κ values per region are shown in Table 5. Especially for liver region disease, readers showed higher agreement for 68Ga-FAPI PET/CT than for 18F-FDG PET/CT and Ce-CT (κ, 0.84, 0.74, and 0.81, respectively). In contrast, interreader agreement for primary, distant nodal, and peritoneal regions was higher for 18F-FDG PET/CT (e.g., 68Ga-FAPI primary κ, 0.28; 18F-FDG PET/CT κ, 0.63; and Ce-CT κ, 0.51) (Table 5). Low agreement on primary region detection for 68Ga-FAPI might be due to pancreatitis pitfalls or scarring in the setting of local recurrence (10).
Reproducibility (n = 38)*
Change in Management
Fifty-nine patients (93.7%) completed and returned the pre- and postimaging questionnaires, and implemented management was assessed by file review (Suppl. Fig. 1). For most of the patients (n = 54; 91.5%), no change in management was documented after 68Ga-FAPI PET. Therapeutic changes were documented for 5 patients (8.5%) and were classified as major (n = 3; e.g., change in therapeutic strategy) or minor (n = 2; e.g., modification of intended therapy or systemic therapy). The treatment plan changed from active surveillance to chemotherapy (major change) for 1 patient, planned biopsies were canceled and chemotherapy was initiated (major change) for 2 patients, and another 2 patients were changed to different systemic treatments (minor change; change to immunotherapy or compassionate-use radioligand therapy) after 68Ga-FAPI PET/CT.
DISCUSSION
FAP was identified as a promising theranostic target for various cancer entities (13,16–18). Early data on 68Ga–FAPI-02 and 68Ga–FAPI-04 provided high uptake values for pancreatic cancer, a tumor entity characterized by a dominant tumor microenvironment, frequent treatment resistance, and a dismal prognosis (1,9).
FAP expression of carcinoma-associated fibroblasts in pancreatic cancer has been described and linked to biologic phenotypes and clinical outcomes of patients (7,19). For the evaluation of 68Ga-FAPI as a noninvasive tool for measuring FAP expression, we correlated tracer uptake with immunohistopathologic FAP expression and found a strong to moderate relationship. However, a considerable limitation of the present study was the heterogeneity of the partially heavily pretreated cohort; therefore, the results should be considered with caution.
To assess the diagnostic value of 68Ga-FAPI PET, we included patients with suspected or proven pancreatic cancer in the ongoing 68Ga-FAPI PET observational trial (NCT04571086) and assessed the association of 68Ga-FAPI PET uptake with FAP expression, validated by FAP IHC, and further analyzed detection rates, diagnostic performance, interreader agreement, and changes in management for a cohort of 62 patients.
Overall, an association between tracer uptake and histopathologic FAP expression for any available sample was observed. We established good diagnostic performance and higher diagnostic accuracy of 68Ga-FAPI PET/CT than of 18F-FDG PET/CT in this cohort. Further, we found almost perfect sensitivity, PPV, NPV, and accuracy of 68Ga-FAPI PET/CT. Additionally, 68Ga-FAPI PET/CT detected more lesions than did 18F-FDG PET/CT and Ce-CT.
Previously, few studies evaluated 68Ga-FAPI PET/CT in pancreatic cancer, but those studies aligned in higher tumor uptake values for 68Ga-FAPI PET/CT than for 18F-FDG PET/CT and partially higher detection rates, leading to upstaging in some patients (10,20,21). In 2021, a retrospective analysis of 19 pancreatic cancer patients showed a TNM change after 68Ga-FAPI PET/CT in 10 of the 19 patients, underlining the potential impact of this new modality (10).
To our knowledge, this is the first observational prospective trial providing a detailed head-to-head comparison of 68Ga-FAPI PET/CT with 18F-FDG PET/CT and Ce-CT, the standard-of-care imaging method. Zhang et al. recently provided data on tumor detection with 68Ga–FAPI-04 PET/MRI and 18F-FDG PET/CT in patients with suspected pancreatic cancer (20). Discordant to the present study, they observed higher detection of primary tumors and liver metastasis with 18F-FDG PET/CT, whereas our data showed better performance of and detection with 68Ga-FAPI PET/CT in all regions. This discrepancy might be explained by cohort heterogeneity and disease extent.
To date, there has been only 1 other study providing diagnostic performance of 68Ga–FAPI-04 PET in pancreatic cancer patients at suspicion or initial diagnosis of the disease (21). Pang et al. showed high sensitivity and accuracy for the primary lesion and for nodal, bone, and visceral metastases, results that partially align with our data (21). However, their study did not provide overall performance on per-patient and per-region bases, hampering direct comparison. Nonetheless, 18F-FDG PET showed worse performance than the results obtained with our cohort and currently available data, which might involve selection bias (22–24).
A secondary endpoint of the observational trial was the determination of changes in clinical management implemented after 68Ga-FAPI PET. In our cohort, 5 changes in management were reported. So far, previously published data provided only upstaging and downstaging numbers and not the resulting clinical impacts, which might not differ drastically in more advanced stages, such as metastatic settings (10,21). Still, in our opinion, impacts on clinical management will increase if 68Ga-FAPI PET is performed in earlier disease stages.
Prospectively, theranostic approaches with 68Ga-FAPI and 177Lu/90Y-FAPI could enable novel cancer treatment strategies against not just tumor but also stromal cells for microenvironmental targeting as well (16,25,26).
Limitations
This trial was limited because of its observational character. We recruited a heterogeneous patient population at various disease stages with mostly metastatic disease. Accordingly, the fact that those patients were heavily pretreated might have affected FAP expression and imaging results. Regulation of FAP expression and therapy-related changes in expression levels are not yet understood. Additionally, pathologic samples were available only for a small number of patients at various time frames and from multiple tumor regions. Further, the type of tissue sampling (e.g., surgery or biopsy) might have influenced the statistical outcome because of sampling errors and lack of representativeness (e.g., needle biopsy). Nonetheless, this cohort reflects the real-life patient distribution in pancreatic cancer. Further, the variety of pancreatic cancer entities, genetic phenotypes, and mutations were not taken into consideration and will need further investigation. A general limitation of 68Ga-FAPI in pancreatic cancer patients is the high tracer uptake in chronic inflammation of the pancreas, which has been reported in several studies (10,21,27). Further, fibrotic or scarred tissue after surgery or other therapies shows tracer uptake as well. These pitfalls are prone to generate false-positive results for primary or locally recurrent lesions, especially with inexperienced readers, and may make it challenging to interpret 68Ga-FAPI PET findings for the evaluation of locally advanced pancreatic cancer. Adjustments of examination protocols or dynamic imaging could help to differentiate tumor from inflammatory tissue.
CONCLUSION
This prospective observational study on pancreatic cancer patients demonstrated an association between FAP expression and the 68Ga-FAPI PET SUVmax. We provided data on diagnostic performance and reproducibility of 68Ga-FAPI PET compared with 18F-FDG PET or Ce-CT. 68Ga-FAPI PET is a valuable diagnostic tool in patients with pancreatic cancer and provided accuracy and the highest lesion detection rate compared with standard imaging modalities. Further, the theranostic potential of radiolabeled FAPI should be investigated.
DISCLOSURE
Ken Herrmann and Jens T. Siveke are supported by the German Federal Ministry of Education and Research (BMBF; 01KD2206A/SATURN3). The work of Jens T. Siveke is supported by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) through 405344257 (SI1549/3-2) and SI1549/4-1, by the German Cancer Consortium (DKTK), and by German Cancer Aid (70112505/PIPAC, 70113834/PREDICT-PACA). Lukas Kessler is consultant for BTG and AAA and has received fees from Sanofi outside of the submitted work. Kim M. Pabst has received a Junior Clinician Scientist Stipend granted by the University Duisburg-Essen, travel fees from IPSEN, and research funding from Bayer. Rainer Hamacher has received travel grants from Lilly, Novartis, and PharmaMar as well as fees from Lilly outside of the submitted work and is supported by the Clinician Scientist Program of the University Medicine Essen Clinician Scientist Academy (UMEA) sponsored by the Faculty of Medicine and the Deutsche Forschungsgemeinschaft (DFG). Benedikt M. Schaarschmidt has received a research grant from PharmaCept for an undergoing investigator-initiated study not related to this work. Ken Herrmann reports receiving personal fees from Bayer, personal fees from SOFIE Biosciences, personal fees from SIRTEX, nonfinancial support from ABX, personal fees from Adacap, personal fees from Curium, personal fees from Endocyte, grants and personal fees from BTG, personal fees from IPSEN, personal fees from Siemens Healthineers, personal fees from GE Healthcare, personal fees from Amgen, personal fees from Novartis, personal fees from ymabs, personal fees from Aktis Oncology, personal fees from Theragnostics, personal fees from Pharma15, personal fees from Debiopharm, personal fees from AstraZeneca, and personal fees from Janssen. Wolfgang P. Fendler reports receiving fees from SOFIE Biosciences (research funding), Janssen (consultant, speaker), Calyx (consultant, image review), Bayer (research funding, consultant, speaker), Novartis (speaker), and Telix (speaker) outside of the submitted work. Jens T. Siveke receives honoraria as a consultant or for continuing medical education presentations from AstraZeneca, Bayer, Boehringer Ingelheim, Bristol-Myers Squibb, Immunocore, MSD Sharp Dohme, Novartis, Roche/Genentech, and Servier outside the submitted work; his institution receives research funding from Abalos Therapeutics, Boehringer Ingelheim, Bristol-Myers Squibb, Celgene, Eisbach Bio, and Roche/Genentech outside the submitted work; and he holds ownership and serves on the Board of Directors of Pharma15 outside the submitted work. No other potential conflict of interest relevant to this article was reported.
KEY POINTS
QUESTION: Is there an association between 68Ga-FAPI tracer uptake intensity and FAP expression in pancreatic cancer and what is the diagnostic performance of 68Ga-FAPI PET in pancreatic cancer patients?
PERTINENT FINDINGS: We observed an association between the 68Ga-FAPI SUVmax and immunohistochemical FAP expression in pancreatic cancer and showed high accuracy and reproducibility of 68Ga-FAPI PET compared with 18F-FDG and Ce-CT.
IMPLICATIONS FOR PATIENT CARE: We demonstrated the diagnostic utility of 68Ga-FAPI PET for pancreatic cancer patients, with future implications for FAP-targeted therapies.
Footnotes
Published online Nov. 16, 2023.
- © 2023 by the Society of Nuclear Medicine and Molecular Imaging.
REFERENCES
- Received for publication February 7, 2023.
- Revision received September 27, 2023.
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