Diagnostic Accuracy of 68Ga-FAPI Versus 18F-FDG PET in Patients with Various Malignancies

To assess the diagnostic accuracy of 68Ga-labeled fibroblast activation protein inhibitor (FAPI) and 18F-labeled FDG PET for the detection of various tumors, we performed a head-to-head comparison of both imaging modalities across a range of tumor entities as part of our ongoing 68Ga-FAPI PET observational trial. Methods: The study included 115 patients with 8 tumor entities who received imaging with 68Ga-FAPI for tumor staging or restaging between October 2018 and March 2022. Of those, 103 patients received concomitant imaging with 68Ga-FAPI and 18F-FDG PET and had adequate lesion validation for accuracy analysis. Each scan was evaluated for the detection of primary tumor, lymph nodes, and visceral and bone metastases. True or false positivity and negativity to detected lesions was assigned on the basis of histopathology from biopsies or surgical excision, as well as imaging validation. Results: 68Ga-FAPI PET revealed higher accuracy than 18F-FDG PET in the detection of colorectal cancer (n = 14; per-patient, 85.7% vs. 78.6%; per-region, 95.6% vs. 91.1%) and prostate cancer (n = 22; per-patient, 100% vs. 90.9%; per-region, 96.4% vs. 92.7%). 68Ga-FAPI PET and 18F-FDG PET had comparable per-patient accuracy in detecting breast cancer (n = 16, 100% for both) and head and neck cancers (n = 10, 90% for both modalities). 68Ga-FAPI PET had lower per-patient accuracy than 18F-FDG PET in cancers of the bladder (n = 12, 75% vs. 100%) and kidney (n = 10, 80% vs. 90%), as well as lymphoma (n = 9, 88.9% vs. 100%) and myeloma (n = 10, 80% vs. 90%). Conclusion: 68Ga-FAPI PET demonstrated higher diagnostic accuracy than 18F-FDG PET in the diagnosis of colorectal cancer and prostate cancer, as well as comparable diagnostic performance for cancers of the breast and head and neck. Accuracy and impact on management will be further assessed in an ongoing prospective interventional trial (NCT05160051).

Fibroblast Activation Protein α-Directed Imaging and Therapy of Solitary Fibrous Tumor

Fibroblast activation protein α (FAPα) is expressed at high levels in several types of tumors. Here, we report the expression pattern of FAPα in solitary fibrous tumor (SFT) and its potential use as a radiotheranostic target. Methods: We analyzed FAPα messenger RNA and protein expression in biopsy samples from SFT patients using immunohistochemistry and multiplexed immunofluorescence. Tracer uptake and detection efficacy were assessed in patients undergoing clinical 68Ga-FAPα inhibitor (FAPI)-46 PET,18F-FDG PET, and contrast-enhanced CT. 90Y-FAPI-46 radioligand therapy was offered to eligible patients with progressive SFT. Results: Among 813 patients and 126 tumor entities analyzed from the prospective observational MASTER program of the German Cancer Consortium, SFT (n = 34) had the highest median FAPα messenger RNA expression. Protein expression was confirmed in tumor biopsies from 29 of 38 SFT patients (76%) in an independent cohort. Most cases showed intermediate to high FAPα expression by immunohistochemistry (24/38 samples, 63%), which was located primarily on the tumor cell surface. Nineteen patients who underwent 68Ga-FAPI-46 PET imaging demonstrated significantly increased tumor uptake, with an SUVmax of 13.2 (interquartile range [IQR], 10.2), and an improved mean detection efficacy of 94.5% (SEM, 4.2%), as compared with 18F-FDG PET (SUVmax, 3.2 [IQR, 3.1]; detection efficacy, 77.3% [SEM, 5.5%]). Eleven patients received a total of 34 cycles (median, 3 cycles [IQR, 2 cycles]) of 90Y-FAPI-46 radioligand therapy, which resulted in disease control in 9 patients (82%). Median progression-free survival was 227 d (IQR, 220 d). Conclusion: FAPα is highly expressed by SFT and may serve as a target for imaging and therapy. Further studies are warranted to define the role of FAPα-directed theranostics in the care of SFT patients.

Oncologic Staging with 68Ga-FAPI PET/CT Demonstrates a Lower Rate of Nonspecific Lymph Node Findings Than 18F-FDG PET/CT

Nonspecific lymph node uptake on 18F-FDG PET/CT imaging is a significant pitfall for tumor staging. Fibroblast activation protein α expression on cancer-associated fibroblasts and some tumor cells is less sensitive to acute inflammatory stimuli, and fibroblast activation protein-directed PET may overcome this limitation. Methods: Eighteen patients from our prospective observational study underwent 18F-FDG and 68Ga fibroblast activation protein inhibitor (FAPI) PET/CT scans within a median of 2 d (range, 0-22 d). Lymph nodes were assessed on histopathology and compared with SUV measurements. Results: On a per-patient basis, lymph nodes were rated malignant in 10 (56%) versus 7 (39%) patients by 18F-FDG PET/CT versus 68Ga-FAPI PET/CT scans, respectively, with a respective accuracy of 55% versus 94% for true lymph node metastases. Five of 6 (83%) false-positive nodes on the 18F-FDG PET/CT scans were rated true negative by the 68Ga-FAPI PET/CT scans. On a per-lesion basis, tumor detection rates were similar (85/89 lesions, 96%). Conclusion: 68Ga-FAPI PET/CT imaging demonstrated higher accuracy for true nodal involvement and therefore has the potential to replace 18F-FDG PET/CT imaging for cancer staging.

68Ga-Labeled Fibroblast Activation Protein Inhibitor (68Ga-FAPI) PET for Pancreatic Adenocarcinoma: Data from the 68Ga-FAPI PET Observational Trial

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.

177Lu-Prostate-Specific Membrane Antigen Therapy in Patients with Metastatic Castration-Resistant Prostate Cancer and Prior 223Ra (RALU Study)

223Ra-dichloride (223Ra) and 177Lu-prostate-specific membrane antigen (PSMA) are approved treatments for metastatic castration-resistant prostate cancer (mCRPC). The safety and effectiveness of sequential use of 223Ra and 177Lu-PSMA in patients with mCRPC are not well described. This study aimed to evaluate 177Lu-PSMA safety and efficacy in patients with mCRPC previously treated with 223Ra. Methods: The radium→lutetium (RALU) study was a multicenter, retrospective, medical chart review. Participants had received at least 1 223Ra dose and, in any subsequent therapy line, at least 1 177Lu-PSMA dose. Primary endpoints included the incidence of adverse events (AEs), serious AEs, grade 3-4 hematologic AEs, and abnormal laboratory values. Secondary endpoints included overall survival, time to next treatment/death, and change from baseline in serum prostate-specific antigen and alkaline phosphatase levels. Results: Data were from 133 patients. Before 177Lu-PSMA therapy, 56% (75/133) of patients received at least 4 life-prolonging therapies; all patients received 223Ra (73% received 5-6 injections). Overall, 27% (36/133) of patients received at least 5 177Lu-PSMA infusions. Any-grade treatment-emergent AEs were reported in 79% (105/133) of patients and serious AEs in 30% (40/133). The most frequent grade 3-4 laboratory abnormalities were anemia (30%, 40/133) and thrombocytopenia (13%, 17/133). Median overall survival was 13.2 mo (95% CI, 10.5-15.6 mo) from the start of 177Lu-PSMA. Conclusion: In this real-world setting, 223Ra followed by 177Lu-PSMA therapy in heavily pretreated patients with mCRPC was clinically feasible, with no indication of impairment of 177Lu-PSMA safety or effectiveness.

Bilobar Radioembolization Carries the Risk of Radioembolization-Induced Liver Disease in the Treatment of Advanced Hepatocellular Carcinoma: Safety and Efficacy Comparison to Systemic Therapy with Atezolizumab/Bevacizumab

Recommended treatment options for advanced-stage hepatocellular carcinoma (HCC) include systemic therapy (ST) and trans-arterial radioembolization (TARE) with Yttrium-90 (Y90). Before the approval of immune-checkpoint inhibitors, a similar safety profile was reported for TARE and ST with tyrosine kinase inhibitors (TKI). However, whole-liver treatment and underlying cirrhosis were identified as risk factors for potentially lethal radioembolization-induced liver disease (REILD). Therefore, the safety and efficacy of TARE and ST with atezolizumab/bevacizumab were compared in patients with advanced HCC involving at least both liver lobes in a retrospective real-world cohort. In total, 74 patients with new or recurrent advanced-stage HCC (BCLC stage B/C) were included if treated with either bilobar TARE (n = 33) or systemic combination therapy with atezolizumab plus bevacizumab (n = 41). Most patients had compensated liver function (90.5% were classified as Child-Pugh Score A, 73% as ALBI Grade 1) at baseline. Although not significant, patients treated with ST showed a more prolonged overall survival than those treated with Y90 TARE (7.1 months vs. 13.0 months, p = 0.07). While a similar disease control rate could be achieved with bilobar TARE and atezolizumab/bevacizumab, in the TARE group, overall survival was curtailed by the occurrence of REILD. In patients with underlying liver cirrhosis, the liver function at baseline was a predictor for REILD.

68Ga-FAPI PET/CT Interobserver Agreement on Tumor Assessment: An International Multicenter Prospective Study

⁶⁸Ga-fibroblast activation protein inhibitors (FAPIs) are promising radiotracers for cancer imaging, with emerging data in the recent years. Nonetheless, the interobserver agreement on ⁶⁸Ga-FAPI PET/CT study interpretations in cancer patients remains poorly understood. Methods: ⁶⁸Ga-FAPI PET/CT was performed on 50 patients with various tumor entities (sarcoma [n = 10], colorectal cancer [n = 10], pancreatic adenocarcinoma [n = 10], genitourinary cancer [n = 10], and other types of cancer [n = 10]). Fifteen masked observers reviewed and interpreted the images using a standardized approach for local, local nodal, and metastatic involvement. Observers were grouped by experience as having a low (<30 prior ⁶⁸Ga-FAPI PET/CT studies; n = 5), intermediate (30-300 studies; n = 5), or high level of experience (>300 studies; n = 5). Two independent readers with a high level of experience and unmasked to clinical information, histopathology, tumor markers, and follow-up imaging (CT/MRI or PET/CT) served as the standard of reference (SOR). Observer groups were compared by overall agreement (percentage of patients matching SOR) and Fleiss κ with mean and corresponding 95% CI. We defined acceptable agreement as a κ value of at least 0.6 (substantial or higher) and acceptable accuracy as at least 80%. Results: Highly experienced observers agreed substantially on all categories (primary tumor: κ = 0.71; 95% CI, 0.71-0.71; local nodal involvement: κ = 0.62; 95% CI, 0.61-0.62; distant metastasis: κ = 0.75; 95% CI, 0.75-0.75), whereas observers with intermediate experience showed substantial agreement on primary tumor (κ = 0.73; 95% CI, 0.73-0.73) and distant metastasis (κ = 0.65; 95% CI, 0.65-0.65) but moderate agreement on local nodal stages (κ = 0.55; 95% CI, 0.55-0.55). Observers with low experience had moderate agreement on all categories (primary tumor: κ = 0.57; 95% CI, 0.57-0.58; local nodal involvement: κ = 0.51; 95% CI, 0.51-0.52; distant metastasis: κ = 0.54; 95% CI, 0.53-0.54). Compared with SOR, the accuracy for readers with high, intermediate, and low experience was 85%, 83%, and 78%, respectively. In summary, only highly experienced readers showed substantial agreement and a diagnostic accuracy of at least 80% in all categories. Conclusion: The interpretation of ⁶⁸Ga-FAPI PET/CT for cancer imaging had substantial reproducibility and accuracy among highly experienced observers only, especially for local nodal and metastatic assessments. Therefore, for accurate interpretation of different tumor entities and pitfalls, we recommend training or experience with at least 300 representative scans for future clinical readers.

Superior Tumor Detection for 68Ga-FAPI-46 Versus 18F-FDG PET/CT and Conventional CT in Patients with Cholangiocarcinoma

Management of cholangiocarcinoma is among other factors critically determined by accurate staging. Here, we aimed to assess the accuracy of PET/CT with the novel cancer fibroblast-directed ⁶⁸Gafibroblast activation protein (FAP) inhibitor (FAPI)-46 tracer for cholangiocarcinoma staging and management guidance. Methods: Patients with cholangiocarcinoma from a prospective observational trial were analyzed. ⁶⁸Ga-FAPI-46 PET/CT detection efficacy was compared with ¹⁸F-FDG PET/CT and conventional CT. SUV_max/tumor-to-background ratio (Wilcoxon test) and separately uptake for tumor grade and location (Mann-Whitney U test) were compared. Immunohistochemical FAP and glucose transporter 1 (GLUT1) expression of stromal and cancer cells was analyzed. The impact on therapy management was investigated by pre- and post-PET/CT questionnaires sent to the treating physicians. Results: In total, 10 patients (6 with intrahepatic cholangiocarcinoma and 4 with extrahepatic cholangiocarcinoma; 6 with grade 2 tumor and 4 with grade 3 tumor) underwent ⁶⁸Ga-FAPI-46 PET/CT and conventional CT; 9 patients underwent additional ¹⁸F-FDG PET/CT. Immunohistochemical analysis was performed on the entire central tumor plain in 6 patients. Completed questionnaires were returned in 8 cases. Detection rates for ⁶⁸Ga- FAPI-46 PET/CT, ¹⁸F-FDG PET/CT, and CT were 5, 5, and 5, respectively, for primary tumor; 11, 10, and 3, respectively, for lymph nodes; and 6, 4, and 2, respectively, for distant metastases. ⁶⁸Ga-FAPI-46 versus ¹⁸F-FDG PET/CT SUV_max for primary tumor, lymph nodes, and distant metastases was 14.5 versus 5.2 (P = 0.043), 4.7 versus 6.7 (P = 0.05), and 9.5 versus 5.3 (P = 0.046), respectively, and tumor-to-background ratio (liver) was 12.1 versus 1.9 (P = 0.043) for primary tumor. Grade 3 tumors demonstrated a significantly higher ⁶⁸Ga-FAPI-46 uptake than grade 2 tumors (SUV_max, 12.6 vs. 6.4; P = 0.009). Immunohistochemical FAP expression was high on tumor stroma (~90% of cells positive), whereas GLUT1 expression was high on tumor cells (~80% of cells positive). Overall, average expression intensity was estimated as grade 3 for FAP and grade 2 for GLUT1. Positive ⁶⁸Ga-FAPI-46 PET findings led to a consequent biopsy workup and diagnosis of cholangiocarcinoma in 1 patient. However, patient treatment was not adjusted on the basis of ⁶⁸Ga-FAPI-46 PET. Conclusion: ⁶⁸Ga-FAPI-46 demonstrated superior radiotracer uptake, especially in grade 3 tumors, and lesion detection in patients with cholangiocarcinoma. In line with this result, immunohistochemistry demonstrated high FAP expression on tumor stroma. Accuracy is under investigation in an ongoing investigator-initiated trial.

Fibroblast Activation Protein Inhibitor Theranostics

The theranostic use of fibroblast activation protein inhibitors (FAPIs) is a novel approach in oncology. Sarcomas are a heterogenous group of rare malignant tumors. Prognosis remains poor in advanced/metastatic disease due to limited therapeutic options. Sarcoma frequently demonstrate high expression of fibroblast activation protein alpha on the tumor cells themselves, in contrast to other solid tumors, where it is mainly expressed on cancer-associated fibroblasts. Consequently, high in vivo uptake of FAPI in PET is observed in sarcoma. Moreover, retrospective case reports and series demonstrated feasibility of FAPI radioligand therapy with signs of tumor response.

Time interval between radium-223 (223Ra) therapy and Lutetium-177–prostate-specific membrane antigen (177Lu-PSMA) treatment and outcomes in the RALU study

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Background: 223Ra and 177Lu-PSMA-617 both prolong overall survival (OS) in different mCRPC settings. The observational, retrospective study, RALU, investigated safety and clinical outcomes of sequential 223Ra/177Lu-PSMA therapy in patients (pts) with mCRPC. This analysis evaluated the association of time interval between 223Ra and 177Lu-PSMA treatments and safety and OS outcomes of 177Lu-PSMA. Methods: Retrospective data were collected from 2021–22 in German nuclear medicine centers for all pts receiving 177Lu-PSMA with prior history of 223Ra therapy. Time intervals were <6 months (mo) (Group [Grp]1) or ≥6 mo (Grp 2) from last 223Ra dose to first 177Lu-PSMA dose. Results: 42 pts received 177Lu-PSMA within 6 mo after 223Ra (Grp 1) and 90 pts received 223Ra ≥6 mo prior to 177Lu-PSMA (Grp 2). Baseline characteristics prior to 177Lu-PSMA therapy were, respectively: median ages 72 and 74 years; 57% and 63% with Eastern Cooperative Oncology Group performance status (ECOG PS) 1, 43% and 37% with ECOG PS 2; median prostate-specific antigen (PSA) values were 366 and 268 ng/ml, and median alkaline phosphatase (ALP) values were 133 and 149 U/L; 40% and 64% received ≥4 life prolonging therapies before starting 177Lu-PSMA. All pts had prior 223Ra; 57% and 77% received 6 223Ra injections; other prior therapies were abiraterone (60%, 77%), enzalutamide (50%, 78%), docetaxel (71%, 76%) and cabazitaxel (17%, 26%). Prior to 177Lu-PSMA, 24% and 29% of pts had visceral metastases. 45% and 52% of pts received ≥4 177Lu-PSMA cycles. From 177Lu-PSMA start to ≤30 days post last dose, 71% and 82% of pts had treatment-emergent adverse events (TEAEs) of any grade; most common were fatigue (12%, 7%), nausea (12%, 8%) and dry mouth (7%, 18%); 36% and 24% of pts had grade 3–4 TEAEs; excluding laboratory abnormalities, osteonecrosis of the jaw was the most frequent grade 3–4 TEAE (5%, 2%). Grade 3–4 laboratory abnormalities (177Lu-PSMA start to ≤90 days post last dose) are shown; treatment-related deaths were reported for 2% and 4% of pts. AEs led to treatment delays in 10% and 9% of pts. Median OS from start of 177Lu-PSMA was 12.0 mo (95% CI, 8.8–19.9) in Grp 1 and 13.2 mo (95% CI, 10.0–15.9) in Grp 2. During 177Lu-PSMA therapy, PSA response ≥50% occurred in 53% and 39% and ALP response ≥30% in 28% and 14% of pts, respectively. Conclusions: In this real-world setting, treating pts with 177Lu-PSMA within 6 mo of completing 223Ra was clinically feasible and well tolerated: no safety signals or concerns were seen. OS outcomes were similar in pts receiving 177Lu-PSMA <6 mo vs. pts receiving it ≥6 mo after completing 223Ra. [Table: see text]

Fibroblast activation protein positron emission tomography and histopathology in a single-center database of 324 patients and 21 tumor entities

Rationale: We present an overview of our prospective fibroblast activation protein inhibitors (FAPI) registry study across a 3-year period, with head-to-head comparison of tumor uptake in ⁶⁸Ga-FAPI and ¹⁸F-FDG PET, as well as FAP immunohistochemistry. Methods: This is an interim analysis of the ongoing ⁶⁸Ga-FAPI PET prospective observational trial at our Department. Patients who underwent clinical imaging with ⁶⁸Ga-FAPI PET between October 2018 and October 2021 were included. Tracer uptake for tumor lesions was quantified by SUV_max and for normal organs by SUVmean. PET tumor volume (40% isocontour) and tumor-to-background ratios (TBR) were calculated. Correlation between SUV_max and FAP staining in tissue samples was analyzed. Results: 324 patients with 21 different tumor entities underwent ⁶⁸Ga-FAPI imaging; 237 patients additionally received ¹⁸F-FDG PET. The most common tumor entities were sarcoma (131/324, 40%), pancreatic carcinoma (67/324, 21%), and primary tumors of the brain (22/324, 7%). Mean primary tumor SUV_max was significantly higher for ⁶⁸Ga-FAPI than ¹⁸F-FDG among pancreatic cancers (13.2 vs. 6.1, p<0.001) and sarcoma (14.3 vs. 9.4, p<0.001), and the same was true for mean SUV_max in metastatic lesions of pancreatic cancers (9.4 vs. 5.5, p<0.001). Mean primary tumor TBRmax was significantly higher for ⁶⁸Ga-FAPI than ¹⁸F-FDG across several tumor entities, most prominently pancreatic cancers (14.7 vs. 3.0, p<0.001) and sarcoma (17.3 vs. 4.7, p<0.001). Compared to ¹⁸F-FDG, ⁶⁸Ga-FAPI showed superior detection for locoregional disease in sarcoma (52 vs. 48 total regions detected) as well as for distant metastatic disease in both, sarcoma (137 vs. 131) and pancreatic cancer (65 vs. 57), respectively. Among 61 histopathology samples, there was a positive correlation between ⁶⁸Ga-FAPI SUV_max and overall FAP immunohistochemistry score (r=0.352, P = 0.005). Conclusion: ⁶⁸Ga-FAPI demonstrates higher absolute uptake in pancreatic cancers and sarcoma, as well as higher tumor-to-background uptake along with improved tumor detection for pancreatic cancers, sarcoma, and other tumor entities when compared to ¹⁸F-FDG. ⁶⁸Ga-FAPI is a new tool for tumor staging with theranostic potential.

Safety and Survival Outcomes of Lutetium-177–Prostate-Specific Membrane Antigen Therapy in Patients with Metastatic Castration-Resistant Prostate Cancer with prior Radium-223 treatment: The RALU Study

The radium lutetium (RALU) study evaluated the feasibility of sequential α- and β-emitter use in patients with bone-predominant metastatic castration-resistant prostate cancer. Methods: This preplanned interim retrospective analysis investigated safety and survival outcomes with ¹⁷⁷Lu-PSMA in patients treated with prior ²²³Ra. Results: Forty-nine patients were evaluated. Patients received a median of 6 ²²³Ra injections; 59% of patients received at least 4 ¹⁷⁷Lu-PSMA cycles. Most (69%) patients received at least 4 life-prolonging therapies before ¹⁷⁷Lu-PSMA. Common Terminology Criteria for Adverse Events grade 3-4 treatment-emergent adverse events during ¹⁷⁷Lu-PSMA therapy and a 30-d follow-up period included anemia (18%) and thrombocytopenia (2%). Median overall survival was 12.6 mo (95% CI, 8.8-16.1 mo) and 31.4 mo (95% CI, 25.7-37.6 mo) from starting ¹⁷⁷Lu-PSMA or ²²³Ra, respectively. Conclusion: ¹⁷⁷Lu-PSMA treatment was well tolerated in patients who had received prior ²²³Ra. ²²³Ra use before ¹⁷⁷Lu-PSMA is feasible and can be considered for future assessment of the optimal treatment sequence.

Safety and Efficacy of 90Y-FAPI-46 Radioligand Therapy in Patients with Advanced Sarcoma and Other Cancer Entities

PURPOSE

We report efficacy and safety of 90Y-labeled FAPI-46 (90Y-FAPI-46-RLT) in patients with advanced sarcoma, pancreatic cancer, and other cancer entities.

EXPERIMENTAL DESIGN

Up to four cycles of radioligand therapy (RLT) were offered to patients with (i) progressive metastatic malignancy, (ii) exhaustion of approved therapies, and (iii) high fibroblast activation protein (FAP) expression, defined as SUVmax ≥ 10 in more than 50% of tumor. Primary endpoint was RECIST response after RLT. Secondary endpoints included PET response (PERCIST), overall survival (OS), dosimetry, and safety of FAP-RLT.

RESULTS

Among 119 screened patients, 21 (18%) were found eligible [n = 16/3/1/1 sarcoma/pancreatic cancer/prostate/gastric cancer; 38% Eastern Cooperative Oncology Group (ECOG) ≥ 2] and received 47 90Y-FAPI-46-RLT cycles; 16 of 21 (76%) patients underwent repeat RLT. By RECIST, disease control was confirmed in 8 of 21 patients [38%; 8/16 (50%) of evaluable patients). There was one partial response (PR) and seven stable diseases after RLT. Disease control was associated with prolonged OS (P = 0.013). PERCIST response was noted in 8 of 21 patients [38%; 8/15 (53%) of evaluable patients]. Dosimetry was acquired in 19 (90%) patients. Mean absorbed dose was 0.53 Gy/GBq in kidney, 0.04 Gy/GBq in bone marrow, and <0.14 Gy/GBq in liver and lung. Treatment-related grade 3 or 4 adverse events were observed in 8 (38%) patients with thrombocytopenia (n = 6) and anemia (n = 6) being most prevalent.

CONCLUSIONS

90Y-FAPI-46-RLT was safe and led to RECIST PR in one case as well as stable disease in about one third of patients with initially progressive sarcomas, pancreatic cancer, and other cancers. Discontinuation after the first cycle and a low rate of PR requires future improvement of FAP-RLT.

Safety and survival outcomes in patients (pts) with metastatic castration-resistant prostate cancer (mCRPC) treated with lutetium-177–prostate-specific membrane antigen (177Lu-PSMA) after radium-223 (223Ra): Interim analysis of the RALU study

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Background: 223Ra and 177Lu-PSMA both prolong overall survival (OS) in different mCRPC settings. Previous data from the observational REASSURE (Sartor O, et al. 2021) and WARMTH (Ahmadzadehfar H, et al. 2021) studies suggested the feasibility of sequencing 223Ra and 177Lu-PSMA therapies. Here we used data from the observational, retrospective RALU study to further examine the safety and clinical outcomes of sequential 223Ra/177Lu-PSMA therapy in pts with mCRPC. Methods: This interim analysis investigated the baseline characteristics, safety (primary endpoint) and OS (secondary endpoint) in pts who received 177Lu-PSMA after 223Ra using retrospective data collected in German centers. Results: Data from 49 pts were available for this interim analysis. At baseline, before the start of 177Lu-PSMA, 73% of pts were Eastern Cooperative Oncology Group performance status (ECOG PS) 1 and 27% ECOG PS 2. Visceral metastases were present in 31% of pts. Median prostate-specific antigen (PSA) and alkaline phosphatase (ALP) were 287 ng/ml and 142 U/L, respectively (Table). 70% of pts received ≥4 life-prolonging therapies prior to 177Lu-PSMA, with abiraterone acetate (80%), enzalutamide (67%) and docetaxel (92%) being the most frequently used. 74% of pts received ≥5 223Ra injections. Pts received either PSMA-617 (67%) or PSMA I&T (33%): 65% of pts received 1–4 cycles and 33% received 5–6 cycles. Median duration of 177Lu-PSMA therapy was 4.9 months (m) (0–57.1). Median time from the last 223Ra dose to first 177Lu-PSMA dose was 9.3 m (0.9–41.9). Any grade treatment-emergent adverse events (TEAEs) from the start of 177Lu-PSMA therapy to 30 days of follow-up occurred in 91.8% of pts, and serious TEAEs in 20% of pts. Grade 3-4 hematologic laboratory abnormalities up to 90 days post-177Lu-PSMA occurred in 34.7% of pts for anemia, 12.8% for thrombocytopenia and 2.0% for neutropenia. No grade 5 toxicities occurred. 39% of pts had ≥30% decline in PSA during 177Lu-PSMA treatment. Median OS was 12.6 m (95% CI 8.8–16.1) from the start of 177Lu-PSMA therapy. Conclusions: In this real-world retrospective analysis of selected pts with advanced mCRPC, the 223Ra/177Lu-PSMA treatment sequence was clinically feasible and well tolerated. [Table: see text]

Clinical Use of PET/MR in Oncology: An Update

The combination of PET and MRI is one of the recent advances of hybrid imaging. Yet to date, the adoption rate of PET/MRI systems has been rather slow. This seems to be partially caused by the high costs of PET/MRI systems and the need to verify an incremental benefit over PET/CT or sequential PET/CT and MRI. In analogy to PET/CT, the MRI part of PET/MRI was primarily used for anatomical imaging. Though this can be advantageous, for example in diseases where the superior soft tissue contrast of MRI is highly appreciated, the sole use of MRI for anatomical orientation lessens the potential of PET/MRI. Consequently, more recent studies focused on its multiparametric potential and employed diffusion weighted sequences and other functional imaging sequences in PET/MRI. This integration puts the focus on a more wholesome approach to PET/MR imaging, in terms of releasing its full potential for local primary staging based on multiparametric imaging and an included one-stop shop approach for whole-body staging. This approach as well as the implementation of computational analysis, in terms of radiomics analysis, has been shown valuable in several oncological diseases, as will be discussed in this review article.

The Future Role of PET Imaging in Metastatic Breast Cancer

BACKGROUND

A variety of therapeutic approaches are employed to treat patients suffering from breast cancer. Likewise, a broad spectrum of imaging ligands has been introduced for non-invasive PET/CT imaging to enable comprehensive tumor characterization and more accurate response evaluation.

SUMMARY

In recent years, novel radioactively labelled ligands have been developed for PET/CT imaging in metastatic breast cancer. One promising tracer is [18F]fluoroestradiol, which was recently approved by the Food and Drug Administration. It can be used for a whole-body assessment of estrogen receptor status. Another radionuclide currently under development is [68Ga]Ga-FAPI. In addition to new radionuclides, the field of application for existing tracers like [18F]fluorodeoxyglucose (FDG) were broadened. It has been shown that an early therapeutic response to various therapies can be detected by [18F]FDG PET/CT, which leads to early treatment optimization. Key Message: In this review, we highlighted new tracers and applications of PET/CT imaging as well as therapeutic approaches in patients with advanced breast cancer. Furthermore, we give an outlook on the application of artificial intelligence, immunoPET and liquid biopsy.

Effects of GH and/or sex steroid administration on abdominal subcutaneous and visceral fat in healthy aged women and men

Aging is associated with reduced GH, IGF-I, and sex steroid axis activity and with increased abdominal fat. We employed a randomized, double-masked, placebo-controlled, noncross-over design to study the effects of 6 months of administration of GH alone (20 microg/kg BW), sex hormone alone (hormone replacement therapy in women, testosterone enanthate in men), or GH + sex hormone on total abdominal area, abdominal sc fat, and visceral fat in 110 healthy women (n = 46) and men (n = 64), 65-88 yr old (mean, 72 yr). GH administration increased IGF-I levels in women (P = 0.05) and men (P = 0.0001), with the increment in IGF-I levels being higher in men (P = 0.05). Sex steroid administration increased levels of estrogen and testosterone in women and men, respectively (P = 0.05). In women, neither GH, hormone replacement therapy, nor GH + hormone replacement therapy altered total abdominal area, sc fat, or visceral fat significantly. In contrast, in men, administration of GH and GH + testosterone enanthate decreased total abdominal area by 3.9% and 3.8%, respectively, within group and vs. placebo (P = 0.05). Within-group comparisons revealed that sc fat decreased by 10% (P = 0.01) after GH, and by 14% (P = 0.0005) after GH + testosterone enanthate. Compared with placebo, sc fat decreased by 14% (P = 0.05) after GH, by 7% (P = 0.05) after testosterone enanthate, and by 16% (P = 0.0005) after GH + testosterone enanthate. Compared with placebo, visceral fat did not decrease significantly after administration of GH, testosterone enanthate, or GH + testosterone enanthate. These data suggest that in healthy older individuals, GH and/or sex hormone administration elicits a sexually dimorphic response on sc abdominal fat. The generally proportionate reductions we observed in sc and visceral fat, after 6 months of GH administration in healthy aged men, contrast with the disproportionate reduction of visceral fat reported after a similar period of GH treatment of nonelderly GH deficient men and women. Whether longer term administration of GH or testosterone enanthate, alone or in combination, will reduce abdominal fat distribution-related cardiovascular risk in healthy older men remains to be elucidated.

Interrelationships of spontaneous growth hormone axis activity, body fat, and serum lipids in healthy elderly women and men

Aging is associated with decreased growth hormone (GH) secretion and plasma insulin-like growth factor-I (IGF-I) levels, increased total and abdominal fat, total and low-density lipoprotein (LDL) cholesterol, and triglycerides, and reduced high-density lipoprotein (HDL) cholesterol. Similar changes in lipids and body composition occur in nonelderly GH-deficient adults and are reversed with GH administration. To examine whether GH/IGF-I axis function in the elderly is related to the lipid profile independently of body fat, we evaluated GH secretion, serum IGF-I and IGF binding protein-3 (IGFBP-3) levels, adiposity via the body mass index (BMI), waist to hip ratio (WHR), dual-energy x-ray absorptiometry (DEXA), and magnetic resonance imaging (MRI), and circulating lipids in 101 healthy subjects older than 65 years. Integrated nocturnal GH secretion (log IAUPGH) was inversely related (P < .005) to DEXA total and abdominal fat and MRI visceral fat in both genders. Log IAUPGH was inversely related to visceral fat in women (P < .005) and men (P < .0001), but was not significantly related to total fat in either gender. In women, log IAUPGH was related inversely to total and LDL cholesterol and positively to HDL cholesterol (P < .008). In men, log IAUPGH was inversely related to total cholesterol and triglycerides (P < .005). In women, HDL cholesterol was inversely related to the WHR (P < .005). In men, triglycerides were positively related (P < .001) to the WHR and DEXA abdominal and MRI visceral fat. Multivariate regression revealed log IAUPGH, but not DEXA total body fat, to be an independent determinant of total (P < .001 for women and P = .01 for men) and LDL (P < .007 and P = .05) cholesterol in both sexes and of HDL cholesterol (P < .005) and triglycerides (P < .03) in women. Log IAUPGH, but not DEXA abdominal fat, was related to total (P < .005 and P < .03) and LDL (P < .03 and P = .05) cholesterol in both genders and to HDL in women (P < .05). Log IAUPGH, but not MRI visceral fat, was related to total cholesterol (P < .03 and P = .05) in women and men. Age, IGF-I, and IGFBP-3 were not significantly related to any body fat or lipid measures, except for a positive correlation of IGF-I with triglycerides in men. Thus, endogenous nocturnal GH secretion predicts total, LDL, and HDL cholesterol levels independently of total or abdominal fat, suggesting that it is an independent cardiometabolic risk factor in healthy elderly people.

4-(2-Aminoethyl)benzenesulfonyl fluoride attenuates tumor-necrosis-factor-alpha-induced blood-brain barrier opening

The effect of serine protease inhibitor 4-(2-aminoethyl)benzenesulfonyl fluoride (AEBSF) was investigated on the prevention of tumor-necrosis-factor-alpha (TNF-alpha)-induced blood-brain barrier opening. TNF-alpha (10,000 IU) was injected intracarotidly to newborn pigs pretreated with 0, 2.4, 4.8, 9.6 and 19.2 mg/kg AEBSF (n = 6 in each group). AEBSF dose-dependently inhibited the TNF-alpha-induced increase in the blood-brain barrier permeability for sodium fluorescein (MW = 376) in all of the five brain regions examined, while only 19.2 mg/kg AEBSF could significantly (P < 0.05) decrease the change in Evan's blue-albumin (MW = 67,000) transport in two regions. In conclusion, AEBSF attenuates vasogenic brain edema formation.

Inhibition of neutrophil and monocyte defensive functions by nicotine

To learn more about the effects of smokeless tobacco on the defensive functions of neutrophils, we studied the influence of nicotine on these cells in vitro, looking at their bactericidal activity against oral pathogens, and at their ability to produce microbicidal reactive oxygen species (oxygen radicals). Exposure of human blood neutrophils to nicotine (0.01% to 0.1%) inhibited their ability to kill Actinomyces naeslundii, Actinobacillus actinomycetemcomitans, and Fusobacterium nucleatum. Although these concentrations of nicotine are high, such concentrations are relevant to phagocytes in the gingival sulcus, because smokeless tobacco contains 0.5% to 3.5% nicotine by dry weight. Nicotine had no such inhibitory effect when the killing assay was performed in an anaerobic environment, implying that nicotine preferentially affected oxygen-dependent killing mechanisms. To further investigate the effects of nicotine on production of oxygen radicals, neutrophils were primed with lipopolysaccharide and triggered with f-met-leu-phe or phorbol ester in the presence of nicotine. Nicotine inhibited production of superoxide anion (measured by reduction of cytochrome c) and hydrogen peroxide (measured by oxidation of phenol red). Nicotine inhibition of superoxide production was reversible by washing away the nicotine. By observing that nicotine inhibited the reduction of cytochrome c by reagent potassium superoxide, we determined that nicotine directly absorbed superoxide. In addition, by examining nicotine inhibition of the uptake of oxygen by neutrophils, we determined that nicotine also interfered with the production of oxygen radicals by these cells. Nicotine also inhibited production of superoxide and interleukin-1 beta by monocytes. Nicotine did not affect the viability of neutrophils and monocytes, as determined by their ability to exclude trypan blue dye. Inhibition of the aerobic antimicrobial functions of neutrophils and monocytes by nicotine may alter the microbial ecology of the oral cavity, and this might be one mechanism by which nicotine compromises the oral health of users of tobacco products.

Serine protease inhibitors block priming of monocytes for enhanced release of superoxide

Monocytes freshly isolated from human blood produced large amounts of superoxide when triggered by phorbol ester. After monocytes were cultured for 18-24 hr in endotoxin-free, non-adherent conditions, they produced low amounts of superoxide. Addition of lipopolysaccharide (LPS), interferon-gamma (IFN-gamma), tumour necrosis factor-alpha (TNF-alpha), or platelet-activating factor (PAF) at the beginning of culture 'primed' the monocytes, causing them to maintain a high superoxide response for at least 96 hr. Also, in response to LPS, monocytes secreted TNF-alpha. The ability of LPS, IFN-gamma, TNF-alpha or PAF to maintain the high superoxide response was blocked by addition of inhibitors of serine proteases, either 4-(2-aminoethyl)-benzenesulphonyl fluoride (AEBSF) or 3,4-dichloroisocoumarin. AEBSF was most effective at 200 microns, and required 6 hr for maximum effect. AEBSF did not affect phorbol-triggered superoxide release by unprimed monocytes. AEBSF did not affect cell viability, nor did it interfere with the TNF-alpha secretion in response to LPS. An analogue of AEBSF that lacked ability to inhibit proteases did not affect monocyte responses. 3,4-Dichloroisocoumarin blocked priming at a low concentration, 1 microM. We conclude that activity of a monocyte serine protease is required to maintain the high superoxide response in monocytes primed with LPS, IFN-gamma, TNF-alpha, or PAF.

Lipopolysaccharide-inactivating activity of neutrophils is due to lactoferrin

Neutrophils can inactivate lipopolysaccharide (LPS), thereby blocking the ability of LPS to prime fresh neutrophils for enhanced fMLP-triggered release of superoxide. Here we show that inactivation of LPS by neutrophils was primarily due to lactoferrin. A time course for inactivating LPS showed that neutrophils (5 million/ml) took 30 min to inactivate 10 ng/ml LPS. Mononuclear cells could not inactivate LPS under the same conditions. Experiments with radioactive LPS showed that inactivated LPS remained in the medium and was not taken up or destroyed by the neutrophils during inactivation. Inactivated LPS still gelled Limulus lysate and primed monocytes. Cell-free medium from neutrophil suspensions also inactivated LPS. A single LPS-inactivating factor was purified from medium by heparin-agarose chromatography. SDS-PAGE showed a single band at 80 kDa, which was identified as lactoferrin by immunoblotting. Antilactoferrin immunoglobulin G removed the LPS-inactivating activity from purified lactoferrin and cell-free medium. Surprisingly, even purified neutrophil lactoferrin required 30 min to inactivate LPS, indicating inherently slow binding of lactoferrin to LPS.

Providing medical care to methadone clinic patients: referral vs on-site care

OBJECTIVES

Intravenous drug users are at high risk for medical illness, yet many are medically underserved. Most methadone treatment programs have insufficient resources to provide medical care. The purpose of this study was to test the efficacy of providing medical care at a methadone clinic site vs referral to another site.

METHODS

Patients with any of four target medical conditions were randomized into an on-site group offered medical care at the methadone treatment clinic and a referred group offered medical care at a nearby clinic. Entry to treatment and use of medical services were analyzed.

RESULTS

Of 161 intravenous drug users evaluated, 75 (47%) had one or more of the target medical conditions. Fifty-one were randomized. In the on-site group (n = 25), 92% received medical treatment; in the referred group (n = 26), only 35% received treatment.

CONCLUSIONS

Providing medical care at a methadone treatment program site is more effective than the usual referral procedure and is a valuable public health intervention.

Disease prevalence among women attending a sexually transmitted disease clinic varies with reason for visit

Prevalence of sexually transmitted diseases (STD) and selected behavioral and demographic variables were evaluated in 279 women attending a Baltimore STD clinic, using a standardized questionnaire and cultures for Neisseria gonorrhoeae, Chlamydia trachomatis, and Trichomonas vaginalis. Stratified by reason for clinic visit, 102 (37%) of 279 women attending the clinic stated that they were recent contacts to men with STDs with the majority (59 out of 102, or 58%) reporting gonorrhea contact as their reason for visit. Another 124 women (44%) came to the clinic for symptom evaluation, and 53 (19%) for other reasons. Prevalence of STDs was higher among those attending as contacts than among noncontacts: 35% versus 15% for N. gonorrhoeae; 26% versus 16% for C. trachomatis; and 27% versus 15% for T. vaginalis (P less than 0.05 for each). Furthermore, multiple infections were found in 23% of those attending as contacts but only in 10% of noncontacts (P less than 0.001). In general, patients reporting contact with an infected person were also less likely to report symptoms (43% versus 34%, P less than 0.001), despite increased disease prevalence. These data suggest that multiple STDs are often present in women attending STD clinics, irrespective of reason for visit. Merely treating women for reported exposure without further evaluation will fail to identify a substantial number of women coinfected with other organisms.

Surrogate methods to diagnose gonococcal and chlamydial cervicitis: comparison of leukocyte esterase dipstick, endocervical gram stain, and culture

This study compared leukocyte esterase dipsticks (LED) and endocervical Gram stains (EGS) as surrogates for culture diagnosis of gonococcal and chlamydial cervicitis in 495 STD clinic patients. Overall, gonorrhea prevalence was 15.7%; chlamydia prevalence (in the subgroup that was tested) was 17.8%. In diagnosing gonorrhea, LED and EGS performed similarly, with sensitivities of 68% and 76%, respectively, and identical specificities of 44%. In diagnosing gonococcal or chlamydial cervicitis, LED and EGS sensitivities fell to 48% and 47%, respectively, whereas specificities increased to 55% and 75%. These data suggest that, although both tests are imperfect surrogates for gonococcal and chlamydial culture, LED sacrifices little in sensitivity compared with EGS. Because LED does not require ancillary supplies, equipment, electricity, or trained personnel, its use may be feasible when Gram-stain diagnosis is impossible. Modifications of LED technology and specimen preparation should be sought to improve LED performance.

Monocyte responses to sulfatide from Mycobacterium tuberculosis: inhibition of priming for enhanced release of superoxide, associated with increased secretion of interleukin-1 and tumor necrosis factor alpha, and altered protein phosphorylation

In monocytes, sulfatide, a lipid from Mycobacterium tuberculosis, blocked priming for enhanced release of superoxide (O2-) by the macrophage activating factors lipopolysaccharide, gamma interferon, interleukin-1 beta (IL-1 beta), tumor necrosis factor alpha (TNF-alpha), and muramyl dipeptide. Sulfatide, in the presence of lipopolysaccharide, also caused increased secretion of IL-1 beta and TNF-alpha into monocyte culture medium. Sulfatide altered the pattern of phosphorylation of monocyte proteins. Cell lysates prepared from monocytes treated with sulfatide showed decreased activity of protein kinase C, but sulfatide did not directly inhibit protein kinase C activity when added to lysates. A known inhibitor of protein kinase C, staurosporine, also inhibited O2- release and caused increased secretion of IL-1 beta. Thus, sulfatide appeared to indirectly affect protein kinase C, implicating protein kinase C as part of the mechanism of priming. Because sulfatide blocked priming for enhanced release of O2-, which could interfere with monocyte bactericidal activity, while causing enhanced secretion of IL-1 beta and TNF-alpha, which could promote formation of granulomata, sulfatide might be an important factor in the pathogenesis of M. tuberculosis.

Multicenter, comparative study of enoxacin and ceftriaxone for treatment of uncomplicated gonorrhea

The efficacy of single dose enoxacin, 400 mg was compared to ceftriaxone, 250 mg IM for therapy of uncomplicated gonorrhea in 152 evaluable patients attending sexually transmitted disease clinics in Baltimore, Indianapolis and Seattle. Anogenital gonorrhea was cured in 75 (99%) of 76 patients treated with enoxacin and 73 (97%) of 75 patients treated with ceftriaxone. Three of three patients with pharyngeal gonorrhea were not cured by enoxacin while all three ceftriaxone treated cases of pharyngeal gonorrhea were cured. All cases of anogenital gonorrhea caused by beta-lactamase producing Neisseria gonorrheae (11 patients), gonococci with high-level, plasmid-mediated tetracycline resistance (11 patients), or gonococci with chromosomally mediated penicillin resistance (22 patients) were cured. The IC90 for enoxacin of N. gonorrhoeae isolated in this study was 0.06 microgram/ml. Enoxacin appears to be a well tolerated, efficacious alternative to currently recommended therapy for patients with uncomplicated, anogenital gonorrhea including cases potentially caused by antibiotic resistant N. gonorrhoeae.