Glucose-Functionalized Liposomes for Reducing False Positives in Cancer Diagnosis

Fluorodeoxyglucose-positron emission tomography (¹⁸F-FDG-PET) is a powerful tool for cancer detection, staging, and follow-up. However, ¹⁸F-FDG-PET imaging has high rates of false positives, as it cannot distinguish between tumor and inflammation regions that both feature increased glucose metabolic activity. In the present study, we engineered liposomes coated with glucose and the chelator dodecane tetraacetic acid (DOTA) complexed with copper, to serve as a diagnostic technology for differentiating between cancer and inflammation. This liposome technology is based on FDA-approved materials and enables complexation with metal cations and radionuclides. We found that these liposomes were preferentially uptaken by cancer cell lines with high metabolic activity, mediated via glucose transporter-1. In vivo, these liposomes were avidly uptaken by tumors, as compared to liposomes without glucose coating. Moreover, in a combined tumor-inflammation mouse model, these liposomes accumulated in the tumor tissue and not in the inflammation region. Thus, this technology shows high specificity for tumors while evading inflammation and has potential for rapid translation to the clinic and integration with existing PET imaging systems, for effective reduction of false positives in cancer diagnosis.

Primary mediastinal B-cell lymphoma - metabolic and anatomical features in 18FDG-PET/CT and response to therapy

Aim of the study

Determining the role of PET/CT imaging in the evaluation of treatment efficacy in primary mediastinal B-cell lymphoma (PMBCL).

Material and methods

Retrospective analysis of seven PMBCL patients, treated at the University Hospital in Krakow, with interim PET/CT after the third course of chemo-immunotherapy.The analysis was based on the calculation of exact tumour volume and metabolic activity, compared with initial values (directly after diagnosis).

Results

Patients (five females, two males, average age 26.2 years, range 18–40 years), in clinical stage IIBX at diagnosis, were treated with eight cycles of R-CHOP-14 regimen, with radiotherapy consolidation (7/7) and central nervous system prophylaxis (6/7). The observed decrease in tumour volume between the initial staging and the interim PET ranged 72–89%. The mean ΔSUV_max reduction between initial (when available) and interim PET was 87% (range 84–89%). In 3/7 cases in the interim PET/CT, the uptake of the tumour was higher than the liver (Deauville Criteria score 4–5), and in 4/7 it was lower than the liver but higher than mediastinal blood pool structures (score 3 according to Deauville Criteria). After a median follow-up of 58 months – OS and EFS is 100%.

Conclusions

The excellent clinical outcome in the study group corresponds with very good metabolic and volumetric response in the interim PET. The ΔSUV_max seems to be easier in implementation and has a more significant impact than other measurements.

The use of interim (18)F-fluorodeoxyglucose PET to guide therapy in lymphoma

Over the past decade (18)F-fluorodeoxyglucose (FDG)-PET combined with computed tomography has gained a central role in the management of patients with lymphoma. The use of FDG-PET for staging and assessing treatment response in Hodgkin's and 'aggressive' non-Hodgkin's lymphoma is now well established, and the prognostic impact of the response to treatment assessed by FDG-PET is being increasingly recognized. Despite the widespread utilization of FDG-PET in clinical practice, key questions remain on its optimal use in certain contexts. One such area that is generating intense interest is the role of interim FDG-PET (typically performed after two to four cycles of chemotherapy) to guide treatment strategies. The author's will review the current available evidence in this area, highlighting questions in need of further study.

State-of-the-Art Research on "Lymphomas: Role of Molecular Imaging for Staging, Prognostic Evaluation, and Treatment Response"

Lymphomas are heterogeneous but potentially curable group of neoplasms. Treatment of lymphomas has rapidly evolved overtime with significant improvement in the cure rate and reductions in treatment-related toxicities. Despite excellent results, treatment programs are continued to be developed to achieve better curative and safety profiles. In these patients individualized therapy schemes can be devised based on a well-defined risk categorization. The therapy efficacy can be increased early during therapy in non-responding patients with escalated therapy protocols or with the addition of radiation therapy, particularly, in advanced-stage or unfavorable risk patients. The increasing availability of positron emission tomography using 18F-fluorodeoxyglucose, particularly fused with computed tomography (FDG-PET/CT) has lead to the integration of this modality into the routine staging and restaging for lymphoma with convincing evidence that it is a more accurate imaging modality compared with conventional imaging techniques. FDG-PET/CT is also is a promising surrogate for tumor chemosensitivity early during therapy. This review will summarize published data on the utility of FDG-PET/CT imaging in the staging, restaging, and predicting therapy response in patients with lymphoma.

Relapse after treatment of pediatric Hodgkin lymphoma: outcome and role of surveillance after end of therapy

BACKGROUND

The outcome of treatment for pediatric Hodgkin lymphoma (HL) is excellent using chemotherapy and radiation. However, a minority of patients will relapse after treatment, but additional therapy achieves durable second remission in many cases. The optimal surveillance strategy after modern therapy for HL has not been well defined.

PROCEDURES

We reviewed the outcomes of pediatric patients with HL treated between 1990 and 2006 to determine the primary event that led to the detection of relapse. We determined the probability of relapse detection by routine follow-up procedures, including history, physical examination, laboratory tests, and imaging, and determined the impact of each of these screening methods on the likelihood of survival after relapse.

RESULTS

Relapse occurred in 64 of 402 evaluable patients (15.9%) at a median of 1.7 years from the time of diagnosis. The majority of relapses (60%) were diagnosed at a routine visit, and patient complaint was the most common initial finding that led to a diagnosis of relapse (47% of relapses). An abnormal finding on physical examination was the primary event in another 17% of relapses, and imaging abnormalities led to the diagnosis in the remaining 36%. Laboratory abnormalities were never the primary finding. The method of detection of relapse and timing (whether detected at a routine visit or an extra visit) did not impact survival.

CONCLUSIONS

In pediatric HL, most relapses are identified through history and physical examination. Frequent imaging of asymptomatic patients does not appear to impact survival and is probably not warranted.

Strikingly high false positivity of surveillance FDG-PET/CT scanning among patients with diffuse large cell lymphoma in the rituximab era

Predictive value (PV) of surveillance fluorodeoxyglucose positron emission tomography (FDG-PET) in patients with diffuse large B-cell lymphoma (DLBCL) treated with chemotherapy-rituximab (R) versus chemotherapy only, remains unclear. The aim of the current study was to compare the performance of surveillance PET in DLBCL patients receiving CHOP (cyclophosphamide, hydroxydaunorubicin hydrochloride, vincristine, and prednisone) alone versus CHOP-R. Institutional database was retrospectively searched for adults with newly diagnosed DLBCL, receiving CHOP or CHOP-R, who achieved complete remission and underwent surveillance PETs. Follow-up (FU) PET was considered positive for recurrence in case of an uptake unrelated to physiological or known benign process. Results were confirmed by biopsy, imaging and clinical FU. One hundred nineteen patients, 35 receiving CHOP and 84 CHOP-R, who underwent 422 FU-PETs, were analyzed. At a median PET-FU of 3.4 years, 31 patients relapsed (17 vs. 14, respectively; P = 0.02). PET detected all relapses, with no false-negative studies. Specificity and positive PV (PPV) were significantly lower for patients receiving CHOP-R vs. CHOP (84% vs. 87%, P = 0.023; 23% vs. 74%, P < 0.0001), reflecting a higher false-positive (FP) rate in subjects receiving CHOP-R (77% vs. 26%, P < 0.001). In the latter group, FP-rate remained persistently high up to 3 years post-therapy. Multivariate analysis confirmed rituximab to be the most significant predictor for FP-PET. In conclusion, routine surveillance FDG-PET is not recommended in DLBCL treated with rituximab; strict criteria identifying patients in whom FU-PET is beneficial are required.

Diffuse large B-cell lymphoma

Diffuse large B-cell lymphoma (DLBCL) is the most common lymphoid malignancy in adults accounting for 31% of all NHL in Western Countries. Following, morphological, biological and clinical studies have allowed the subdivision of DLBCLs into morphological variants, molecular and immunophenotypic subgroups and distinct disease entities. However, a large number of cases still remain biologically and clinically heterogeneous, for which there are no clear and accepted criteria for subclassification; these are collectively termed DLBCL, not otherwise specified (NOS). DLBCL-NOS occurs in adult patients, with a median age in the seventh decade, but the age range is broad, and it may also occur in children. Clinical presentation, behaviour and prognosis are variable, depending mainly of the extranodal site when they arise. These malignancies present in localized manner in approximately 20% of patients. Disseminated extranodal disease is less frequent, and one third of patients have systemic symptoms. Overall, DLBCLs are aggressive but potentially curable malignancies. Cure rate is particularly high in patients with limited disease with a 5-year PFS ranging from 80% to 85%; patients with advanced disease have a 5-year PFS ≈ 50%. The International Prognostic Index (IPI) and age adjusted IPI (aaIPI) are the benchmarks of DLBCL prognosis. First-line treatment for patients with DLBCL is based on the individual IPI score and age, and three major subgroups should be considered: elderly patients (>60 years, aaIPI=0-3); young patients with low risk (<60 years, aaIPI=0-1); young patients with high risk (<60 years, aaIPI=2-3). The combination of the anti-CD20 monoclonal antibody rituximab and CHOP chemotherapy, every 14 or 21 days, is the standard treatment for DLBCL patients. Recent randomized trials suggest that high-dose chemotherapy supported by autologous stem cell transplant (HDC/ASCT) should not be used as upfront treatment for young high-risk patients outside prospective clinical trials. HDC/ASCT is actually recommended in young patients who did not achieve CR after first-line chemotherapy. Consolidation radiotherapy should be reserved to patients with bulky disease who did not achieve CR after immunochemotherapy. Patients with high IPI score, which indicates increased LDH serum level and the involvement of more than one extranodal site, and patients with involvement of certain extranodal sites (a.e., testes and orbit) should receive CNS prophylaxis as part of first-line treatment. HDC/ASCT should be considered the standard therapy for DLBCL patients with chemotherapy-sensitive relapse. Overall results in patients who cannot be managed with HDC/ASCT due to age or comorbidity are disappointing. New effective and less toxic chemotherapy drugs or biological agents are also worth considering for this specific and broad group of patients. Several novel agents are undergoing evaluation in DLBCL; among other, immunomodulating agents (lenalidomide), m-TOR inhibitors (temsirolimus and everolimus), proteasome inhibitors (bortezomib), histone deacetylase inhibitors (vorinostat), and anti-angiogenetic agents (bevacizumab) are being investigated in prospective trials.

Interim FDG PET/CT as a prognostic factor in diffuse large B-cell lymphoma

PURPOSE

Interim (18)F-FDG PET performed early during the course of therapy in diffuse large B-cell lymphoma (DLBCL) is a good predictor of outcome. However, interpretation criteria for interim PET for the evaluation of tumour response are still not clearly defined. The study aim was to assess whether interim PET can predict overall survival (OS) and progression-free survival (PFS) in DLBCL patients following three different sets of parameters, two qualitative (visual) methods and one semiquantitative.

METHODS

A total of 50 newly diagnosed DLBCL patients were prospectively enrolled in this study. All patients had a PET/CT scan at diagnosis and an interim PET/CT scan after the second or third cycle of chemotherapy. Three methods of evaluation for the interim PET/CT were used: a qualitative three-point scoring (3-PS) method, a qualitative 5-PS method and a semiquantitative method (ΔSUVmax). The degree of correlation between therapy response seen on FDG PET and PFS and OS was determined.

RESULTS

The analysis of the visual 3-PS method showed no statistically significant difference in PFS and OS. The estimated 5-year PFS and OS were 79 % and 92 %, respectively, in patients with an interim PET scan showing uptake not greater than in the liver versus 50 % in patients with uptake greater than in the liver, and this difference was statistically significant. The optimal cut-off value of ΔSUVmax that could predict the PFS and OS difference in patients with DLBCL was 76 % (95 % CI 62.7-89.2 %) and 75 % (95 % CI, 54.6-95.4 %), respectively.

CONCLUSION

Our results support the use of liver uptake as an indicator in the qualitative evaluation of interim PET, or a ΔSUVmax greater than 75 % in semiquantitative analysis. Interim PET may predict PFS and OS and could be considered in the prognostic evaluation of DLBCL.

18-Fluorodeoxyglucose Positron Emission Tomography/Computed Tomography in the Management of Aggressive Non-Hodgkin's B-Cell Lymphoma

18-Fluorodeoxyglucose (FDG-PET/CT) is an established imaging modality that has been proven to be of benefit in the management of aggressive B-cell non-Hodgkin's lymphoma, such as diffuse large B-cell lymphoma and advanced stage follicular lymphoma. The combination of anatomic and functional imaging afforded by FDG-PET/CT has led to superior sensitivity and specificity in the primary staging, restaging, and assessment of response to treatment of hematological malignancies when compared to FDG-PET and CT alone. The use of FDG-PET/CT for posttreatment surveillance imaging remains controversial, and further study is needed to ascertain whether this modality is cost effective and appropriate for use in this setting.

Interim 18-FDG-PET/CT failed to predict the outcome in diffuse large B-cell lymphoma patients treated at the diagnosis with rituximab-CHOP

Role of interim-PET (I-PET) in diffuse large B-cell Lymphoma (DLBCL) is controversial. To determine predictive value of I-PET on progression-free survival (PFS), we enrolled 88 first-line DLBCL patients treated with 6-8 R-CHOP courses regardless of I-PET. PET/CT were performed at diagnosis, after 2 to 4 courses and at the end of therapy with central reviewing according to visual dichotomous criteria. Results are as follows: I-PET, 72% negative, 28% positive; final-PET (F-PET), 88% negative, 12% positive; clinical complete response 90%. Concordance between clinical response and F-PET negativity was 97% because of 2 false positive. With a median follow-up of 26.2 months, 2-year overall survival and PFS were 91% and 77%, respectively. Two-year PFS for I-PET and F-PET negative versus positive were as follows: I-PET 85% versus 72% (P = .0475); F-PET 83% versus 64% (P < .001). Because of a small number of events, 2 independent bivariate Cox models were tested for PFS. In model 1, F-PET contradicted I-PET (hazard ratio [HR] = 5.03, P = .015 vs 1.27, P = 691); in model 2, F-PET (HR = 4.54) and International propnostic Index score (HR = 5.36, P = .001) remained independent prognostic factors. In conclusion, positive I-PET is not predictive of a worse outcome in DLBCL; larger prospective studies and harmonization of I-PET reading criteria are needed.

Plasma thymus and activation-regulated chemokine as an early response marker in classical Hodgkin's lymphoma

BACKGROUND

Plasma thymus and activation-regulated chemokine is a potential biomarker for classical Hodgkin's lymphoma. To define its value as a marker to monitor treatment response, we correlated serial plasma thymus and activation-regulated chemokine levels with clinical response in newly diagnosed and relapsed classical Hodgkin's lymphoma patients.

DESIGN AND METHODS

Plasma was collected from 60 (39 early stage and 21 advanced stage) newly diagnosed classical Hodgkin's lymphoma patients before, during, and after treatment, and from 12 relapsed patients before and after treatment. Plasma thymus and activation-regulated chemokine levels were determined by enzyme-linked immunosorbent assay and were related to pre-treatment metabolic tumor volume, as measured by quantification of 2-[18F]fluoro-2-deoxyglucose positron emission tomography images, and to treatment response.

RESULTS

Baseline plasma thymus and activation-regulated chemokine levels correlated with stage of disease and bulky disease, and more closely with metabolic tumor volume. Response to treatment was observed among 38 of 39 early stage and 19 of 21 advanced stage patients. Reduction in plasma thymus and activation-regulated chemokine to normal range levels could be observed as early as after one cycle of chemotherapy in all responsive patients, while plasma levels remained elevated during and after treatment in the 3 non-responsive patients. Plasma thymus and activation-regulated chemokine was elevated in all 12 relapsed patients at time of relapse and remained elevated after salvage treatment in the 4 non-responsive patients.

CONCLUSIONS

Baseline plasma thymus and activation-regulated chemokine levels correlate with classical Hodgkin's lymphoma tumor burden and serial levels correlate with response to treatment in patients with classical Hodgkin's lymphoma.

Impact of FDG-PET/CT in the management of lymphoma

Since the introduction of (67)Gallium-citrate 30 years ago, nuclear medicine has played an important role in the evaluation of malignant lymphoma. During that time, several radiotracers were evaluated as potential alternatives for the diagnosis of lymphoma, but the introduction of (18)F-fluorodeoxyglucose PET (FDG-PET) marked a major turning point. FDG-PET took over most of the role of gallium, and is now an essential tool in the diagnosis of lymphoma. FDG-PET is increasingly being used for assessment of the tumor staging prior to treatment, for evaluating the response to treatment, and for monitoring the early reactions to therapy to predict the final outcome. FDG-PET has been shown to have more accurate diagnostic capability than conventional CT and MRI for distinguishing the tumor necrosis and residual masses frequently seen after therapy in lymphoma patients without any clinical and biochemical manifestation. Malignant lymphoma is the first disease for which FDG-PET was adopted as a tool for response assessment in the international standard criteria. However, lymphoma does not always display a clear high uptake, and there are some pitfalls in assessing the response to therapy. This review will highlight the most important applications of FDG-PET in lymphoma, focusing on the advantages and pitfalls of this imaging, and past and ongoing efforts to standardize the use of FDG-PET, particularly in response to assessment and therapy monitoring.

18F-FDG-PET/CT in the surveillance of patients with lymphoma: detection of asymptomatic recurrences

AIM

To assess the diagnostic accuracy of (18)F-FDG-PET/CT in detecting asymptomatic recurrences in patients with lymphoma. To define uptake patterns of recurrence indicative of recurrence.

MATERIAL AND METHODS

Those patients with lymphoma who fulfilled the following inclusion criteria of clinical complete remission and negative PET/CT study were included retrospectively and longitudinally. Conventional surveillance of these patients was performed only by (18)F-FDG PET/CT following a standardized procedure. Pathologic locations (supra- and infradiaphragmatic) and their character (single or multiple) were analyzed in order to determine reliable metabolic patterns of recurrence. The final diagnosis was established by histopathological analysis or clinical follow-up greater than 8 months.

RESULTS

A total of 199 explorations belonging to 106 patients with lymphoma were included. Of these patients, 59 had Hodgkin's lymphoma and 47 non-Hodgkin's lymphoma. There was suspicion of relapse from the metabolic point of view in 27 of the PET/CT scans. Of these, 14 (10 patients) were false positive (FP), and 13 (8 patients) true positive. The remaining studies were true negative, no false negatives being detected. The pattern most frequently related to recurrence was infradiaphragmatic lymph node involvement while most of the FP had isolated supradiaphragmatic involvement. Sensitivity, specificity, PPV, NPV and diagnostic accuracy of PET/CT parameters for the study were 100%, 92%, 48%, 100% and 93%, respectively.

CONCLUSION

(18)F-FDG-PET/CT is a sensitive technique in the detection of asymptomatic recurrences in patients with lymphoma during their follow-up. Multiple character and infradiaphragmatic locations were the patterns that best correlated to the diagnosis of recurrence.

Role of Functional Imaging in the Management of Lymphoma

18-F-fluorodeoxyglucose (FDG) –positron emission tomography (PET), and more recently PET/computed tomography (CT), is the most sensitive and specific imaging technique currently available for patients with lymphoma. Nevertheless, despite being increasingly used in pretreatment assessment, midtreatment evaluation of response, post-treatment restaging, and surveillance during follow-up of patients with lymphoma, its impact on clinical outcome in most clinical situations remains to be confirmed. PET/CT provides its greatest clinical benefit in the post-treatment evaluation of Hodgkin's lymphoma and diffuse large B-cell lymphoma; however, the role of metabolic imaging in other indications and in other histologies remains to be demonstrated. Ongoing risk-adapted studies will hopefully provide evidence for clinical improvement on the basis of altering treatment as a result of interim PET results. Efforts are ongoing to better standardize the conduct and interpretation of FDG-PET scans. FDG-PET has the potential to improve lymphoma patient management; however, its usefulness will likely vary by histology, stage, therapy, and clinical setting.

Opportunities and pitfalls of cancer imaging in clinical trials

Cancer treatment strategies have changed considerably over the past two decades, with increasing emphasis on cancer-specific biological therapies. This situation has led to the incorporation of biomarkers, including those obtained by medical imaging, into trial designs to better understand mechanisms of action and, hopefully, to provide early evidence of treatment efficacy at a molecular or physiological level. Unlike blood tests and tissue samples, an imaging biomarker allows assessment of treatment in the whole tumor, in all tumors in the body, and at multiple time points. This situation has increased the complexity of clinical trials, as each imaging modality has issues related to cost, ease of use, patient compatibility, data analysis, and interpretation. This article reviews strengths and limitations of the current imaging methods available in clinical cancer trials, including MRI, CT, PET, and ultrasonography. The information gained by each test, and the difficulties in acquiring the data and interpreting it are also discussed in order to help researchers plan imaging in clinical trials and interpret data from such studies.

FDG-PET/CT in lymphoma

Molecular Imaging has played a prominent role in the assessment of lymphoma for now almost three decades since the introduction of (67)Ga-citrate imaging for staging and restaging of both Hodgkin's and non-Hodgkin's lymphoma (HL and NHL). Since then other molecular probes have been investigated for more accurate pre- and posttreatment assessment of lymphomas but none of these probes was widely accepted and utilized until the emergence of (18)F-fluorodeoxyglucose positron emission tomography (FDG-PET). FDG-PET or FDG-PET/CT, which combines FDG-PET with CT scanning, is now widely utilized for response assessment of lymphoma after completion of therapy, for pretreatment staging, and, increasingly, also for assessment of response during therapy (therapy monitoring). Particularly for response assessment at therapy conclusion, FDG-PET has been shown to be considerably more accurate than CT or conventional MRI because of its ability to distinguish between viable tumor and necrosis or fibrosis in posttherapy residual mass (es) that are frequently present in patients with lymphoma without any other clinical or biochemical evidence of disease. FDG-PET/CT is therefore the noninvasive modality of choice for response classifications of HL and aggressive NHLs consistent with the recently revised, primarily FDG-PET/CT-based, response criteria for lymphoma. This review will highlight the most important applications of FDG-PET (FDG-PET/CT) in lymphoma emphasizing the strengths and pitfalls of this imaging approach, past and ongoing efforts to standardize the use of FDG-PET, particularly in response assessment and therapy monitoring. Other promising molecular probes for lymphoma imaging will also be briefly discussed.

PET imaging for pediatric oncology: an assessment of the evidence

Positron emission tomography (PET) has shown potential benefits when used in therapeutic clinical trials for children with cancer. However, existing trials are limited in scope with small numbers of patients and varied observations, making accurate conclusions about the usefulness of PET scanning impossible. This review examines PET and its applications in pediatric oncology. While evidence is limited, there appears to be a basis for rigorous evaluation of this imaging modality before widespread application without validation from clinical trials.

Midtreatment 18F-fluorodeoxyglucose positron-emission tomography in aggressive non-Hodgkin lymphoma

BACKGROUND

The use of (18) F-fluorodeoxyglucose positron-emission tomography (PET) scan has increased considerably in the clinical management of non-Hodgkin lymphoma patients, and its role as a prognostic factor during chemotherapy has been established recently.

METHODS

Between May 2003 and May 2009, 91 newly diagnosed patients with primary mediastinal large B-cell lymphoma (PMLBCL) and diffuse large B-cell lymphoma (DLBCL) were treated with 12 weekly cycles of rituximab-MACOP-B (n = 12 patients with PMLBCL), 6 cycles of rituximab-CHOP21 (n = 65 patients with DLBCL, aged < 60 years and 1 patient with PMLBCL), or 8 weekly cycles of rituximab-VNCOP-B (n = 13 DLBCL patients, aged ≥ 60 years). All patients underwent a staging PET examination at baseline and a midtreatment (interim) PET examination after 6 weeks of rituximab-MACOP-B treatment, 3 cycles of rituximab-CHOP21 treatment, or 4 weeks of rituximab-VNCOP-B treatment and again at the end of the chemo-immunotherapy regimen.

RESULTS

At midtreatment evaluation, 35 patients showed a persistently positive PET scan; only 6 (17%) of these patients achieved a continuous complete response (CCR). However, 56 patients presented with a negative interim PET, and 50 (89%) of these patients achieved and maintained a CCR. Comparison between the 2 PET groups indicated a statistically significant association between PET findings and event-free survival (P = .0001) and overall survival (P = .0001).

CONCLUSIONS

The results of this study indicated that midtreatment PET may represent a significant step forward in helping physicians make crucial decisions on further treatment. Cancer 2011. © 2010 American Cancer Society.