Comparison of the EORTC criteria and PERCIST in solid tumors: a pooled analysis and review

Prognostic value of [18F]-FDG PET/CT in patients with meta-static breast cancer treated with cyclin-dependent inhibitors

Objective

The addition of cyclin-dependent kinase 4/6 inhibitors (CDK4/6i) to endocrine therapy impressively improved the outcome of patients with hormone receptor-positive metastatic breast cancer. Despite their great efficacy, not all patients respond to treatment and many of them develop acquired resistance. The aim of this retrospective study was to assess the role of [18F]-FDG PET/CT in predicting PFS and OS in breast cancer patients treated with CDK4/6i.

Methods

114 patients who performed an [18F]-FDG PET/CT scan before (PET1) and 2-6 months (PET2) after starting treatment were retrospectively enrolled. Metabolic response was evaluated by EORTC, PERCIST and Deauville Score and correlated to PFS and OS.

Results

In patients who did not progress at PET2 (n = 90), PFS rates were not significantly different between classes of response by EORTC and PERCIST. Conversely, patients showing a Deauville score ≤3 had a longer PFS (median PFS 42 vs 21.0 months; p = 0.008). A higher total metabolic tumor volume at PET1 (TMTV1) was also associated with a shorter PFS (median 18 vs 42 months; p = 0.0026). TMTV1 and Deauville score were the only independent prognostic factors for PFS at multivariate analysis and their combination stratified the population in four definite classes of relapse risk. Conversely, the above parameters did not affect OS which was only influenced by a progressive metabolic disease at PET2 (3-years survival rate 29.8 vs 84.9%; p<0.0001).

Conclusion

TMTV and metabolic response by Deauville score were significant prognostic factors for PFS in patients with breast cancer treated with CDK4/6i. Their determination could help physicians to select patients who may need a closer follow up.

PET Criteria by Cancer Type from Imaging Interpretation to Treatment Response Assessment: Beyond FDG PET Score

Background: in recent years, the role of positron emission tomography (PET) and PET/computed tomography (PET/CT) has emerged as a reliable diagnostic tool in a wide variety of pathological conditions. This review aims to collect and review PET criteria developed for interpretation and treatment response assessment in cases of non-[18F]fluorodeoxyglucose ([18F]FDG) imaging in oncology. Methods: A wide literature search of the PubMed/MEDLINE, Scopus and Google Scholar databases was made to find relevant published articles about non-[18F]FDG PET response criteria. Results: The comprehensive computer literature search revealed 183 articles. On reviewing the titles and abstracts, 149 articles were excluded because the reported data were not within the field of interest. Finally, 34 articles were selected and retrieved in full-text versions. Conclusions: available criteria are a promising tool for the interpretation of non-FDG PET scans, but also to assess the response to therapy and therefore to predict the prognosis. However, oriented clinical trials are needed to clearly evaluate their impact on patient management.

Multisystem Imaging Recommendations/Guidelines: In the Pursuit of Precision Oncology

With an increasing rate of cancers in almost all age groups and advanced screening techniques leading to an early diagnosis and longer longevity of patients with cancers, it is of utmost importance that radiologists assigned with cancer imaging should be prepared to deal with specific expected and unexpected circumstances that may arise during the lifetime of these patients. Tailored integration of preventive and curative interventions with current health plans and global escalation of efforts for timely diagnosis of cancers will pave the path for a cancer-free world. The commonly encountered circumstances in the current era, complicating cancer imaging, include coronavirus disease 2019 infection, pregnancy and lactation, immunocompromised states, bone marrow transplant, and screening of cancers in the relevant population. In this article, we discuss the imaging recommendations pertaining to cancer screening and diagnosis in the aforementioned clinical circumstances.

Gastrointestinal stromal tumors: a comprehensive radiological review

Gastrointestinal stromal tumors (GISTs) originating from the interstitial cells of Cajal in the muscularis propria are the most common mesenchymal tumor of the gastrointestinal tract. Multiple modalities, including computed tomography (CT), magnetic resonance imaging (MRI), fluorodeoxyglucose positron emission tomography, ultrasonography, digital subtraction angiography, and endoscopy, have been performed to evaluate GISTs. CT is most frequently used for diagnosis, staging, surveillance, and response monitoring during molecularly targeted therapy in clinical practice. The diagnosis of GISTs is sometimes challenging because of the diverse imaging findings, such as anatomical location (esophagus, stomach, duodenum, small bowel, colorectum, appendix, and peritoneum), growth pattern, and enhancement pattern as well as the presence of necrosis, calcification, ulceration, early venous return, and metastasis. Imaging findings of GISTs treated with antineoplastic agents are quite different from those of other neoplasms (e.g. adenocarcinomas) because only subtle changes in size are seen even in responsive lesions. Furthermore, the recurrence pattern of GISTs is different from that of other neoplasms. This review discusses the advantages and disadvantages of each imaging modality, describes imaging findings obtained before and after treatment, presents a few cases of complicated GISTs, and discusses recent investigations performed using CT and MRI to predict histological risk grade, gene mutations, and patient outcomes.

A Role for PET/CT in response assessment of malignant pleural mesothelioma

Malignant pleural mesothelioma is a rare type of cancer, whose incidence, however, is increasing and will presumably continue to rise in the coming years. Key features of this disease comprise its mantle-shaped, pleura-associated, often multifocal growth, which cause diagnostic challenges. A growing number of mesotheliomas are being treated with novel immunotherapies for which no image derived general response criteria have been established. However, recent studies indicate that FDG-PET/CT could be superior for response assessment compared to CT-based criteria. This article aims at providing an overview of response assessment criteria dedicated to malignant pleural mesothelioma, such as mRECIST, iRECIST, and PERCIST. In addition, the potential future role of PET/CT in the management of malignant pleural mesothelioma will also be discussed.

New tools to investigate tumor metabolism by NMR/MRI

Changes in metabolism is an hallmark that characterizes tumour cells from healthy ones. Their detection can be highly relevant for staging the tumor and for monitoring the response to therapeutic treatments. Herein it is shown the readout of these changes can be achieved either by assessing the pH of the extracellular space in the tumour region and by monitoring real time transformations of hyperpolarized C-13 labelled substrates. Mapping pH in a MR image is possible by measuring the CEST response of an administered contrast agent such as Iopamidol that can provide accurate measurements of the heterogeneity of tumour acidosis. Direct detection of relevant enzymatic activities have been acquired by using Pyruvate and Fumarate hyperpolarized by the incorporation of a molecule of para-H₂. Finally, it has been found that the tumour transformation involves an increase in the water exchange rate between the intra- and the extra-cellular compartments. A quantitative estimation of these changes can be obtained by acquiring the longitudinal relaxation times of tissue water protons at low magnetic field strength on Fast Field Cycling Relaxometers. This finding has been exploited in an application devoted to the assessment of the presence of residual tumour tissue in the margins of the resected mass in breast conservative surgery.

The role of Ga68 PSMA PET/CT imaging in Lu177 PSMA treatment planning in metastatic castration-resistant prostate cancer

OBJECTIVE

Lutetium-177 (Lu¹⁷⁷) prostate-specific membrane antigen (Lu¹⁷⁷ PSMA) is a novel targeted treatment for patients with metastatic castration-resistant prostate cancer (CRPC). The purpose of the study was to determine the molecular volumetric Gallium-68 (Ga⁶⁸) PSMA PET/CT parameters that can predict patients who will respond to treatment.

METHODS

These single-center retrospective data were obtained from metastatic CRPC patients receiving intravenous 6.0-8.5 GBq Lu¹⁷⁷ PSMA treatment every 6-8 weeks for a maximum of 3-8 cycles, with baseline Ga⁶⁸ PSMA PET/CT scan, clinical data, and information on treatment responses. All lesions were divided into two groups according to the increase and decrease in PSMA expression levels of 600 bone lesions and 85 lymph nodes that were compatible with metastasis of 23 patients after the treatment. The primary endpoint of our study was the evaluation of the relation between the baseline SUVmax, PSMA TV, TL PSMA values, and the treatment response of the two groups. The threshold values were determined for the parameters that had significant relations. In the present study, the prostate-specific antigen (PSA) response and treatment-induced toxicities were also evaluated as the secondary endpoint.

RESULTS

It was found that SUVmax, PSMA TV, and TL PSMA values in bone metastases showed significant differences between the groups with decreased and increased PSMA expression levels after the treatment. The AUC value for SUVmax was significant (AUC = 0.677; p < 0.001). The cutoff value was > 10.50 (sensitivity = 91.8%, Specificity = 41.5%) for SUVmax, > 1.50 cm³ (sensitivity = 49.1%, specificity = 70%) for PSMA TV and > 8.50 g (sensitivity = %60.9, specificity = %72.2) for TL PSMA. The median SUVmax value before the treatment in all metastatic lymph nodes was found to be 7.1 (5.4-12.4), and the median SUVmax after the treatment was 2.5 (1.6-12.1) (p < 0.001).

CONCLUSION

It was shown in the present study that Lu¹⁷⁷ PSMA treatment response may be higher in CRPC patients with metastatic bone lesion with high baseline PSMA expression level, and better treatment response may be achieved in patients with lymph node metastases than in bone metastases.

Assessment of Treatment Response to Lenvatinib in Thyroid Cancer Monitored by F-18 FDG PET/CT Using PERCIST 1.0, Modified PERCIST and EORTC Criteria-Which One Is Most Suitable?

Background: We aimed to compare the established metabolic response criteria PERCIST and EORTC for their applicability and predictive value in terms of clinical response assessment early after the initiation of lenvatinib therapy in patients with metastatic radioiodine-refractory (RAI) thyroid cancer (TC). Methods: In 25 patients treated with lenvatinib, baseline and 4-month follow-up F-18 FDG PET/CT images were analyzed using PERCIST 1.0, modified PERCIST (using SUVpeak or SUVmax) and EORTC criteria. Two groups were defined: disease control (DC) and progressive disease (PD), which were correlated with PFS and OS. Results: PERCIST, mPERCIST, PERCISTmax and EORTC could be applied in 80%, 80%, 88% and 100% of the patients based on the requirements of lesion assessment criteria, respectively. With PERCIST, mPERCIST, PERCISTmax and EORTC, the patients classified as DC and PD ranged from 65 to 68% and from 32 to 35%, respectively. Patients with DC exhibited a longer median PFS than patients with PD for EORTC (p < 0.014) and for PERCIST and mPERCIST (p = 0.037), respectively. Conclusion: EORTC and the different PERCIST criteria performed equally regarding the identification of patients with PD requiring treatment changes. However, the applicability of PERCIST 1.0 using SULpeak seems restricted due to the significant proportion of small tumor lesions.

Review of imaging techniques for evaluating morphological and functional responses to the treatment of bone metastases in prostate and breast cancer

Bone metastases are very common complications associated with certain types of cancers that frequently negatively impact the quality of life and functional status of patients; thus, early detection is necessary for the implementation of immediate therapeutic measures to reduce the risk of skeletal complications and improve survival and quality of life. There is no consensus or universal standard approach for the detection of bone metastases in cancer patients based on imaging. Endorsed by the Spanish Society of Medical Oncology (SEOM), the Spanish Society of Medical Radiology (SERAM), and the Spanish Society of Nuclear Medicine and Molecular Imaging (SEMNIM) a group of experts met to discuss and provide an up-to-date review of our current understanding of the biological mechanisms through which tumors spread to the bone and describe the imaging methods available to diagnose bone metastasis and monitor their response to oncological treatment, focusing on patients with breast and prostate cancer. According to current available data, the use of next-generation imaging techniques, including whole-body diffusion-weighted MRI, PET/CT, and PET/MRI with novel radiopharmaceuticals, is recommended instead of the classical combination of CT and bone scan in detection, staging and response assessment of bone metastases from prostate and breast cancer.Clinical trial registration: Not applicable.

Intracellular Water Lifetime as a Tumor Biomarker to Monitor Doxorubicin Treatment via FFC-Relaxometry in a Breast Cancer Model

This study aims to explore whether the water exchange rate constants in tumor cells can act as a hallmark of pathology status and a reporter of therapeutic outcomes. It has been shown, using 4T1 cell cultures and murine allografts, that an early assessment of the therapeutic effect of doxorubicin can be detected through changes in the cellular water efflux rate constant kio. The latter has been estimated by analyzing the magnetization recovery curve in standard NMR T1 measurements when there is a marked difference in the proton relaxation rate constants (R1) between the intra- and the extra-cellular compartments. In cellular studies, T1 measurements were carried out on a relaxometer working at 0.5 T, and the required difference in R1 between the two compartments was achieved via the addition of a paramagnetic agent into the extracellular compartment. For in-vivo experiments, the large difference in the R1 values of the two-compartments was achieved when the T1 measurements were carried out at low magnetic field strengths. This task was accomplished using a Fast Field Cycling (FFC) relaxometer that was properly modified to host a mouse in its probe head. The decrease in kio upon the administration of doxorubicin is the result of the decreased activity of Na+/K+-ATPase, as shown in an independent test on the cellular uptake of Rb ions. The results reported herein suggest that kio can be considered a non-invasive, early and predictive biomarker for the identification of responsive patients immediately from the first doxorubicin treatment.

Combined Metabolically Active Tumor Volume and Early Metabolic Response Improve Outcome Prediction in Metastatic Colorectal Cancer

Stratification of metastatic colorectal cancer (mCRC) patients is mostly based on clinical and biological characteristics. This study aimed to validate the prognostic value of ¹⁸F-FDG PET/CT-based biomarkers such as baseline whole-body metabolically active tumor volume (WB-MATV) and early metabolic response (mR) in mCRC. Methods: The development cohort included chemorefractory mCRC patients enrolled in two prospective Belgian multicenter trials evaluating last-line treatments (multikinase inhibitors). The validation cohort included mCRC patients from an Italian center treated with chemotherapy and bevacizumab as first-line. Baseline WB-MATV was defined as the sum of metabolically active volumes of all target lesions identified on the baseline ¹⁸F-FDG PET/CT. Early metabolic response (mR) assessment was performed following usual response criteria (PERCIST-30%, PERCIST-15%, EORTC) and the so-called CONSIST method, which defines response as a decrease of SULmax ≥ 15% for all target lesions. Baseline WB-MATV and early mR assessment were investigated along with usual clinical factors and correlated with overall and progression-free survival (OS/PFS). Results: Clinical factors, baseline WB-MATV and early mR were evaluable in 192/239 and 94/125 patients of the development and validation cohorts, respectively. Except for PERCIST-30%, all response methods were equivalent in terms of outcome prediction and CONSIST was found to be the most accurate. Baseline WB-MATV and early mR using CONSIST method were independent prognostic parameters after adjustment for clinical factors in the development and validation sets for both OS (HR WB-MATV: 1.87 (1.17-2.97), P = 0.005, and HR early mR: 1.79 (1.08-2.95), P = 0.02 for the validation set), and PFS (HR WB-MATV: 1.94 (1.27-2.97), P = 0.002, and HR early mR: 1.69 (1.04-2.73), P = 0.03 for the validation set). Conclusion: Baseline WB-MATV and early mR are strong independent prognostic biomarkers for OS/PFS in mCRC, regardless of treatment received. Therefore, combining these biomarkers improves risk stratification for OS/PFS in mCRC.

Freezing Nodal Disease: Local Control Following Percutaneous Image-Guided Cryoablation of Locoregional and Distant Lymph Node Oligometastases: A 10-Year, Single-Center Experience

PURPOSE

To retrospectively assess the technical feasibility, safety, and oncologic outcomes of percutaneous image-guided cryoablation (PCA) of locoregional and distant lymph node metastases (LNMs).

METHODS

All consecutive patients undergoing PCA of LNMs between February 2009 and December 2019 were identified using a retrospective database search. Every patient was followed up at 1, 3, 6, and 12 months after treatment using contrast-enhanced magnetic resonance imaging and at approximately 3-6-month intervals using computed tomography or positron emission tomography-computed tomography. The Kaplan-Meier method was used to calculate local tumor progression-free survival, disease-free survival, and overall survival. Locoregional and distant groups were compared using the Fisher test. Technical success, technique efficacy, complications, and oncologic outcomes were analyzed.

RESULTS

Fifty-six metachronous oligometastatic LNMs (median size, 15 mm [interquartile range, 13-15 mm; range, 9-36 mm]) were treated in 37 sessions in 29 patients and defined as locoregional (26/37 sessions) or distant (11/37 sessions). Seventeen patients had undergone prior surgery or radiotherapy. Six patients underwent 8 retreatments for locoregional progression. An additional visceral oligometastasis was treated in 4 of the 11 distant LNM PCA sessions. The technical success and primary technique efficacy rates were 100%. The complication rate was 5.4% (2 transient nerve palsies). At a median follow-up of 23 months, there were 2 instances of local tumor progression (5.6%); the 1-, 2-, and 3-year local tumor progression-free survival was 100%, 94.3%, and 94.3%, respectively. Thirteen (45%) patients demonstrated no disease progression. The 1-, 2-, and 3-year overall survival was 96.2%, 90.5%, and 70%, respectively. The patients were free from systemic oncologic therapy following 20 (54%) sessions, with a mean treatment break of 19.1 months.

CONCLUSIONS

The PCA of lymph node oligometastases is feasible and safe, and offers promising local tumor control at midterm follow-up.

Imaging and clinical correlates with regorafenib in metastatic colorectal cancer

In colorectal cancer (CRC), imaging is important in determining tumor stage, selecting treatment strategies, and in assessing response to therapy. However, some challenges remain with established imaging techniques, such as computed tomography, and with some commonly used response criteria, such as Response Evaluation Criteria in Solid Tumors, which measures change in size of several target lesions instead of change in tumor morphology or metabolic function. In addition, these assessments are not typically conducted until after 8 weeks of treatment, meaning that potential non-responders are often not identified in a timely manner. Regorafenib, an oral tyrosine kinase inhibitor indicated for the treatment of metastatic CRC, blocks the activity of several protein kinases involved in angiogenesis, oncogenesis, metastasis, and tumor immunity. Timely differentiation of regorafenib responders from non-responders using appropriate imaging techniques that recognize not only changes in tumor size but also changes in tumor density or vasculature, may reduce unnecessary drug-related toxicity in patients who are unlikely to respond to treatment. This review discusses the latest developments in computed tomography, magnetic resonance imaging, and positron emission tomography tumor imaging modalities, and how these aid in identifying patients with metastatic CRC who are responders or non-responders to regorafenib treatment.

Imaging for Response Assessment in Radiation Oncology: Current and Emerging Techniques

Imaging in radiation oncology is essential for the evaluation of treatment response in tumors and organs at risk. This influences further treatment decisions and could possibly be used to adapt therapy. This review article focuses on the currently used imaging modalities for response assessment in radiation oncology and gives an overview of new and promising techniques within this field.

Radiologic Modalities and Response Assessment Schemes for Clinical and Preclinical Oncology Imaging

Clinical drug trials for oncology have resulted in universal protocols for medical imaging in order to standardize protocols for image procurement, radiologic interpretation, and therapeutic response assessment. In recent years, there has been increasing interest in using large animal models to study oncologic disease, though few standards currently exist for imaging of large animal models. This article briefly reviews medical imaging modalities, the current state-of-the-art in radiologic diagnostic criteria and response assessment schemes for evaluating therapeutic response and disease progression, and translation of radiologic imaging protocols and standards to large animal models of malignant disease.

The use of molecular volumetric parameters for the evaluation of Lu-177 PSMA I&T therapy response and survival

PURPOSE

The primary aim of this study was to evaluate the volumetric therapy response via Ga-68 PSMA I&T PET/CT in patients treated with Lu-177 PSMA I&T therapy. The secondary purpose was to determine the impact of volumetric parameter responses to overall survival.

METHODS

PSMA tumor volumes (PSMA-TV) and tumor lesion PSMA expressions (TL-PSMA) were calculated with a semi-automatic program on Ga-68 PSMA I&T PET/CT images that were obtained before and after Lu-177 PSMA I&T therapies with 19 patients. The median overall survival was compared with PSMA-TV, TL-PSMA, SUV_max, PSA, and alteration in PERCIST criteria.

RESULTS

PSMA-TV values were decreased in 12 patients (63%), and TL-PSMA values were decreased in 15 patients (79%) following the therapy. The SUV_max and the PSA values were also decreased in 14 (74%) and 10 (53%) patients, respectively. The complete remission (CR) was observed in two patients (10%). The partial response (PR) and progressive disease were observed in 6 (32%) and 11 (58%) patients, respectively, according to PRECIST criteria. The survival rates were statistically significant in patients with a decrease in PSMA-TV and TL-PSMA values than patients without any decrease (p 0.001, p < 0.001, respectively). However, the survival rates did not differ in responders (PR or CR) and non-responders according to the PERCIST criteria (p 0.232). The survival rates did not also differ in responders and non-responders according to the SUV_max and PSA values (p 0.140, p 0.206, respectively).

CONCLUSIONS

Molecular and volumetric parameters are beneficial in the assessment of Lu-177 PSMA I&T therapy response. Although the number of patients is small, TL-PSMA response, which includes both the tumor volume and PSMA expression in tumor, may be considered as the most valuable parameter for the evaluation of the therapy response and the prediction of survival rate.

Regorafenib in Patients with Antiangiogenic-Naïve and Chemotherapy-Refractory Advanced Colorectal Cancer: Results from a Phase IIb Trial

BACKGROUND

Regorafenib is a multikinase inhibitor with antiangiogenic effects that improves overall survival (OS) in metastatic colorectal cancer (mCRC) after failure of standard therapies. We investigated the efficacy and safety of regorafenib in antiangiogenic therapy-naïve chemotherapy-refractory advanced colorectal cancer.

PATIENTS AND METHODS

This single-center, single-arm, phase IIb study (NCT02465502) enrolled adults with mCRC whose disease had progressed on, or who were intolerant to, standard therapy, but who were antiangiogenic therapy-naïve. Patients received regorafenib 160 mg once daily for 3 weeks per 4-week cycle. The primary endpoint was progression-free survival (PFS) rate at week 8.

RESULTS

Of 59 treated patients, almost half had received at least four prior lines of therapy. Patients received a median of 86% of the planned dose. The week 8 PFS rate was 53% (95% confidence interval [CI], 39.1-64.3); median PFS was 3.5 months (95% CI, 1.8-3.6). Median OS was 7.4 months (95% CI, 5.3-8.9). Tumor response (RECIST version 1.1) was 2%, and metabolic response rate (criteria from the European Organisation for Research and Treatment of Cancer) was 41%. The most frequently reported regorafenib-related grade ≥3 adverse events were hypertension (36%), hand-foot skin reaction (HFSR, 25%), and hypophosphatemia (24%). There were no regorafenib-related deaths. An exploratory analysis showed that patients with grade ≥2 HFSR had longer OS (10.2 months) with regorafenib treatment versus those with grades 0-1 (5.4 months).

CONCLUSION

These findings support the antitumor activity of regorafenib in antiangiogenic-naïve patients with chemotherapy-refractory mCRC.

IMPLICATIONS FOR PRACTICE

The multikinase inhibitor regorafenib improved overall survival in the phase III CORRECT and CONCUR trials in heavily pretreated patients with treatment-refractory metastatic colorectal cancer (mCRC). Exploratory subgroup analysis from CONCUR suggested that regorafenib treatment prior to targeted therapy (including bevacizumab) may improve outcomes. In this single-center, single-arm phase IIb study, regorafenib demonstrated antitumor activity in 59 antiangiogenic-naïve patients with chemotherapy-refractory mCRC. Further studies should assess the efficacy of regorafenib in this patient population, as well as explore the reasons behind improved outcomes among patients who had a metabolic response and those who developed hand-foot skin reaction.

Comparison of the morphologic criteria (RECIST) and metabolic criteria (EORTC and PERCIST) in tumor response assessments: a pooled analysis

BACKGROUND/AIMS

The Positron Emission Tomography Response Criteria in Solid Tumors (PERCIST) or European Organization for Research and Treatment of Cancer (EORTC) criteria are used to assess metabolic tumor responses. However, tumor responses have shown considerable discrepancies between the morphologic criteria (Response Evaluation Criteria in Solid Tumors [RECIST]) and metabolic criteria. We performed this pooled study to compare the RECIST and metabolic criteria in the assessment of tumor responses.

METHODS

Electronic databases were searched for eligible articles with the terms "RECIST," "PERCIST," or "EORTC criteria." The level of concordance in the tumor responses between the two criteria was estimated using κ statistics.

RESULTS

A total of 216 patients were collected from eight studies comparing the RECIST and EORTC criteria. The agreement of tumor responses between the two criteria was moderate (κ = 0.447). Eighty-six patients (39.8%) showed disagreement: tumor response was upgraded in 70 patients and downgraded in 16 when adopting the EORTC criteria. The EORTC criteria significantly increased the overall response rate (53% vs. 28%, p < 0.0001). The agreement of tumor responses between the RECIST and PERCIST was deemed fair (κ = 0.389). Of 407 patients from nine studies, 181 (44.5%) showed a discrepancy: using the PERCIST, tumor response were upgraded in 151 patients and downgraded in 30. When adopting the PERCIST, the overall response rate was also significantly increased from 30% to 55% (p < 0.0001).

CONCLUSION

This pooled analysis demonstrates that the concordance of tumor responses between the morphologic criteria and metabolic criteria is not excellent. When adopting the metabolic criteria instead of the RECIST, overall response rates were significantly increased.

Response to Single Low-dose 177Lu-DOTA-EB-TATE Treatment in Patients with Advanced Neuroendocrine Neoplasm: A Prospective Pilot Study

Objective:¹⁷⁷Lu-DOTA-EB-TATE is a theranostic agent based on octreotate that uses an Evans blue structure to bind albumin to improve the pharmacokinetics and pharmacodynamics. This pilot study aims to evaluate the efficacy of a single low-dose treatment using ¹⁷⁷Lu-DOTA-EB-TATE in patients with advanced neuroendocrine neoplasm (NEN).

Methods: With IRB approval and informed consent, 4 NEN patients were enrolled to undergo ¹⁷⁷Lu-DOTA-EB-TATE treatment with a single low dose of 0.66 ± 0.06 GBq (17.8 ± 1.7 mCi); 3 other NEN patients were enrolled as controls to undergo ¹⁷⁷Lu-DOTA-TATE treatment with administered activity of 3.98 ± 0.17 GBq (107.6 ± 4.6 mCi). One primary tumor and 62 metastatic lesions in the 7 patients were evaluated by ⁶⁸Ga-DOTA-TATE PET/CT immediately before and one or three months after the treatment. Maximum SUV (SUV_max) of the tumors ≥2.0 cm in diameter were measured and percentage of change (ΔSUV) after treatment were calculated.

Results: All 4 patients subjected to ¹⁷⁷Lu-DOTA-EB-TATE treatment tolerated the administered activity without significant adverse effects and showed symptomatic remission. Among the patients, 40 tumors were found with diameter ≥2.0 cm, with the baseline SUV_max varied from 1.5-82.9 (35.9 ± 21.0) and the ΔSUVs before and three months after the treatment from -75.1-26.3% (-38.9 ± 25.5%). Twenty-nine (72.5%) of the tumors showed >15% decrease of SUV_max (ΔSUV = -75.1%--17.1%). There was a significant negative correlation between the baseline SUV_max and the ΔSUV after treatment (r = -0.852, P < 0.001). Compared with the control ¹⁷⁷Lu-DOTA-TATE therapy, the ¹⁷⁷Lu-DOTA-EB-TATE treatment using approximately 1/6 the dose showed no significant difference in ΔSUV (-7.9 ± 5.4% vs. -5.8 ± 3.9%, P = 0.189) as demonstrated by the tumors with comparable baseline SUV_max from 10.0-35.0.

Conclusion: A single low-dose ¹⁷⁷Lu-DOTA-EB-TATE treatment appears to be safe and effective in the treatment of NENs with high ⁶⁸Ga-DOTA-TATE uptake. This pilot study merits further investigation with increased dose and frequency of ¹⁷⁷Lu-DOTA-EB-TATE administration with potential advantages over ¹⁷⁷Lu-DOTA-TATE.

The role of interim 18F-FDG PET/CT in prediction of response to ipilimumab treatment in metastatic melanoma

PURPOSE

The aim of the present study was to assess the value of interim ¹⁸F-FDG PET/CT performed after the first two cycles of ipilimumab treatment in the prediction of the final clinical response to this type of immunotherapy.

METHODS

The study group comprised 41 patients with unresectable metastatic melanoma scheduled for ipilimumab therapy. Whole-body ¹⁸F-FDG PET/CT was performed before the start of ipilimumab treatment (baseline PET/CT) and after the initial two cycles of ipilimumab treatment (interim PET/CT). Evaluation of patient response to treatment was based on the European Organization for Research and Treatment of Cancer (EORTC) 1999 criteria for PET as well as the recently proposed PET Response Evaluation Criteria for Immunotherapy (PERCIMT). The patients' best clinical response, assessed at a median of 21.4 months (range 6.3-41.9 months) was used as reference.

RESULTS

According to their best clinical response, the patients were divided into two groups: those showing clinical benefit (CB) including stable disease, partial response and complete response (31 patients), and those showing no clinical benefit (no-CB including progressive disease (10 patients). According to the EORTC criteria, interim PET/CT demonstrated progressive metabolic disease (PMD) in 20 patients, stable metabolic disease (SMD) in 11 patients, partial metabolic response (PMR) in 8 patients, and complete metabolic response (CMR) in 2 patients. According to the PERCIMT, interim PET/CT demonstrated PMD in 9 patients, SMD in 24 patients, PMR in 6 patients and CMR in 2 patients. On the basis of the interim PET, the patients were divided in a similar manner to the division according to clinical response into those showing metabolic benefit (MB) including SMD, PMR and CMR, and those showing no metabolic benefit (no-MB) including PMD. According to this dichotomization, the EORTC criteria showed a sensitivity (correctly predicting CB) of 64.5%, a specificity (correctly predicting no-CB) of 90.0%, a positive predictive value (PPV) of 95.2%, a negative predictive value (NPV) of 45.0% and an accuracy of 70.7% in predicting best clinical response. The PERCIMT showed a sensitivity of 93.6%, a specificity of 70.0%, a PPV of 90.6%, a NPV of 77.8% and an accuracy of 87.8%. The McNemar test showed that the PERCIMT had a significantly higher sensitivity than EORTC criteria (p = 0.004), while there was no significant difference in specificity (p = 0.5). The agreement between the two sets of criteria was poor (McNemar test p = 0.001, and accordingly kappa = 0.46).

CONCLUSION

The application of the recently proposed PERCIMT to interim ¹⁸F-FDG PET/CT provides a more sensitive predictor of final clinical response to immunotherapy than the application of the EORTC criteria in patients with metastatic melanoma.

Evaluating tumor response with FDG PET: updates on PERCIST, comparison with EORTC criteria and clues to future developments

Eighteen years ago, the EORTC PET criteria standardized for the first time response assessment by FDG PET. Response assessment by FDG PET has been further developed and refined by PERCIST (PET response criteria in solid tumors). This review describes the data underlying these two systems for assessing tumor response on FDG PET/CT. It also summarizes recent clinical studies that have compared EORTC criteria and PERCIST with each other as well as with the anatomically based "response criteria in solid tumors" (RECIST). These studies have shown that response assessment by EORTC criteria and PERCIST leads to very similar response classifications. In contrast, there are significant differences between response assessment by PERCIST and RECIST. Preliminary data also suggest that response assessment by PERCIST is better correlated with patient outcome and may be a better predictor for the effectiveness of new anti-cancer therapies than RECIST. If correct, this could have a significant impact on oncologic drug development. However, confirmation of the better predictive value of response assessment by PERCIST by data from randomized trials is still lacking.