Activities of DNA-PK and Ku86, but not Ku70, may predict sensitivity to cisplatin in human gliomas

Objective To explore prospectively the positive predictive value of O-(2-[¹⁸F]fluoroethyl)-l-tyrosine (FET)–PET in selected patients with a magnetic resonance imaging (MRI)-based suspicion of a glioma recurrence or progression. Methods Patients with a supratentorial glioma (initial World Health Organization (WHO) grade II, III or IV) were considered eligible if they had both an MRI-(new/progressive contrast-enhancing lesion) and FET–PET-based diagnosis of a recurrence/progression after various forms and combinations of irradiation and chemotherapy. Criterion for tumour recurrence/progression in FET–PET was a standardized uptake value (SUVmax)/Background (BG) ratio of >2.0 in the late uptake phase. All patients underwent multimodal (MRI, FET–PET) imaging-guided stereotactic biopsy. The positive predictive value was defined as the proportion of MRI and FET–PET findings indicating glioma recurrence/progression that also tested positive for tumour recurrence/progression after stereotactic biopsy. Results Thirty-one patients with initially WHO grade II (17), WHO grade III (6), and grade IV glioma (8) were included. In 26 patients FET–PET results indicating tumour recurrence/progression were concordant with the biopsy results. In five patients histopathologic evaluation failed to reveal a “vital” tumour. FET–PET findings were also discordant with the radiographic and clinical follow-up in these five patients. The positive predictive value of FET–PET was 84%. Conclusion The positive predictive value of FET–PET using the standard ratio method is high, but not high enough to replace stereotactic biopsy in this highly selected study cohort. Whether the calculation of FET uptake in the early phase and/or the evaluation of uptake kinetics will improve the positive predictive value of FET–PET deserves prospective evaluation.     

Prognostic value of CD57<Superscript>+</Superscript> T lymphocytes in the peripheral blood of patients with advanced gastric cancer

Background  Natural killer (NK)-like T cells comprising CD56⁺ T cells and CD57⁺ T cells belong to a subset of CD1d-independent NKT cells playing an important role in regulating immune responses. Although NK-like T cells are reported to increase in patients with advanced gastric carcinomas, it remains unknown how NK-like T cells are involved in disease progression in gastric cancer patients. Methods  The proportions of Th1 cells (interferon [IFN]-γ-producing CD4⁺ T cells), Th2 cells (IL-4-producing CD4⁺ T cells), and NK-like T cells (CD56⁺ T cells and CD57⁺ T cells) in the peripheral blood of 48 gastric cancer patients and 20 healthy controls were measured by two-color flow cytometry analysis and by intracellular cytokine analysis to investigate an association of these immune cells with the survival rate of gastric cancer patients. Results  Univariate analysis showed that Th1 cells and CD57⁺ T cells, as well as some clinicopathological factors, significantly influenced the survival rate. CD57-high (≧18%) patients survived for a significantly shorter period after surgery compared to CD57-low patients (P = 0.046; Kaplan-Meier, log-rank test) in the stage III–IV patients, but not in the stage I–II patients. Further, multivariate analysis showed that lymphatic invasion was a statistically significant independent risk factor in all the gastric cancer patients, but the proportion of CD57⁺ T cells as well as depth of tumor were statistically significant independent risk factors in patients with advanced carcinomas (stage III–IV). Conclusion  An increased proportion (≧18%) of CD57⁺ T cells in the peripheral blood of patients with advanced gastric carcinomas could indicate a poor prognosis.     

AAA and PBC calculation accuracy in the surface build-up region in tangential beam treatments. Phantom and breast case study with the Monte Carlo code penelope

Background and purpose

In tangential beam treatments accurate dose calculation of the absorbed dose in the build-up region is of major importance, in particular when the target has superficial extension close to the skin. In most analytical treatment planning systems (TPSs) calculations depend on the experimental measurements introduced by the user in which accuracy might be limited by the type of detector employed to perform them. To quantify the discrepancy between analytically calculated and delivered dose in the build-up region, near the skin of a patient, independent Monte Carlo (MC) simulations using the penelope code were performed. Dose distributions obtained with MC simulations were compared with those given by the Pencil Beam Convolution (PBC) algorithm and the Analytical Anisotropic Algorithm (AAA) implemented in the commercial TPS Eclipse.

Material and methods

A cylindrical phantom was used to approximate the breast contour of a patient for MC simulations and the TPS. Calculations of the absorbed doses were performed for 6 and 18 MV beams for four different angles of incidence: 15°, 30°, 45° and 75° and different field sizes: 3 × 3 cm², 10 × 10 cm² and 40 × 40 cm². Absorbed doses along the phantom central axis were obtained with both the PBC algorithm and the AAA and compared to those estimated by the MC simulations. Additionally, a breast patient case was calculated with two opposed 6 MV photon beams using all the aforementioned analytical and stochastic algorithms.

Results

For the 6 MV photon beam in the phantom case, both the PBC algorithm and the AAA tend to underestimate the absorbed dose in the build-up region in comparison to MC results. These differences are clinically irrelevant and are included in a 1 mm range. This tendency is also confirmed in the breast patient case. For the 18 MV beam the PBC algorithm underestimates the absorbed dose with respect to the AAA. In comparison to MC simulations the PBC algorithm tends to underestimate the dose after the first 2-3 mm of tissue for larger angles but seems to be in good agreement for smaller angles. In the first millimetre of depth instead the PBC tends to overestimate the dose for smaller angles and underestimate it for larger angle of incidence. Instead, the AAA overestimates absorbed doses with respect to MC results for all angles of incidence and at all depths. This behaviour seems to be due to the electron contamination model, which is not able to provide accurate absorbed doses in the build-up region. Even for this case the differences are unlikely to be of clinical significance as 18 MV is not usually used to treat superficial targets.

Conclusions

The PBC algorithm and the AAA implemented in the TPS Eclipse system version 8.0.05, both yield equivalent calculations, after the first 2 mm of tissue, of the absorbed dose for 6 MV photon beams when a grid size smaller than 5 mm is used. When 18 MV photon beams are used care should be taken because the results of the AAA are highly dependent on the beam configuration.     

High 2-[F]fluoro-2-deoxy-d-glucose (FDG) uptake measured by positron emission tomography is associated with reduced overall survival in patients with oral squamous cell carcinoma

Patients with oral squamous cell carcinoma (OSCC) and poor prognosis may benefit from an intensification of the initial therapy scheme. To improve the clinical management of these patients, there is a strong requirement for an accurate assessment of the malignant properties of the individual lesion. The objective of the present analysis was to define the potential value of 2-[¹⁸F]fluoro-2-deoxy-d-glucose (¹⁸FDG) uptake in the tumor measured by positron emission tomography (PET) in predicting patients’ outcome in the clinical course of OSCC. In this respect, a clinically well-defined cohort of 79 patients with primary OSCC was retrospectively evaluated. ¹⁸FDG uptake in the primary tumor site was quantified by calculation of the maximum standardized uptake values (SUV_max). Subsequent statistical analyses found, that ¹⁸FDG uptake of the primary tumor was significantly higher in stage T3/T4 vs. T1/T2 (p < 0.001), in UICC stage IV vs. stage I–III (p = 0.01), and in N1–3 vs. N0 tumors (p < 0.001), respectively. To define SUV_max cut-off values for survival analyses, receiver operating curves (ROC) were calculated for overall and disease-free survival after 36 and 60 months, respectively. Univariate survival analysis showed that high SUV_max was significantly associated with shortened overall survival after 36 (p = 0.026) and 60 months (p = 0.02). Subsequent multi-variate Cox regression analysis including SUV_max, age, gender and UICC stage as co-variables determined that, high SUV_max was the only predictor of inferior overall survival after 60 months (p = 0.035) in this model. In conclusion, ¹⁸FDG uptake detected by PET predicts adverse outcome of patients with OSCC in this retrospective analysis. ¹⁸FDG–PET might be a promising tool to contribute to therapeutic decisions and should be evaluated in future prospective studies.     

Comparison of (immuno-)fluorescence data with serial [F]Fmiso PET/CT imaging for assessment of chronic and acute hypoxia in head and neck cancers

Purpose

Both, acute and chronic hypoxia can have unfavorable impacts on tumor progression and therapy response. The aim of this study was to optimize a macroscopic technique for the quantification of acute and chronic hypoxia (Wang model assessment of serial [¹⁸F]Fmiso PET/CT imaging) by comparing with a microscopic technique [(immuno-)fluorescence staining in tumor cryosections].

Materials and methods

Tumor pieces from the human squamous cell carcinoma lines from the head and neck FaDu and CAL33 were xenografted into the hind leg of NMRI nu/nu mice. Tumor-bearing mice were placed on an in-house developed multi-point fixation system and subjected to two consecutive dynamic [¹⁸F]Fmiso PET/CTs within a 24 h interval. The Wang model was applied to SUV (standard uptake values) to quantify the fractions of acute and chronic hypoxia. Hypoxia subtypes were also assessed in vital tumor tissue of cryosections from the same tumors for (immuno-)fluorescence distributions of Hoechst 33342 (perfusion), pimonidazole (hypoxia), and CD31 (endothelium) using pattern recognition in microcirculatory supply units (defined as vital tumor tissue area supplied by a single microvessel).

Results

Using our multi-point fixation system, acceptable co-registration (registration errors ε ranged from 0.34 to 1.37) between serial PET/CT images within individual voxels was achieved. The Wang model consistently yielded higher fractions of acute hypoxia than the MCSU method. Through specific modification of the Wang model (Wang_mod), it was possible to reduce the fraction of acute hypoxia. However, there was no significant correlation between the fractions of acute hypoxia in individual tumors assessed by the Wang_mod model and the MCSU method for either tumor line (FaDu: r = 0.68, p = 0.21 and CAL33: r = 0.71, p = 0.18). This lack of correlation is most-likely due to the difference between the non-linear uptake of [¹⁸F]Fmiso and the spatial assessment of MCSUs.

Conclusions

Whether the Wang model can be used to predict radiation response after serial [¹⁸F]Fmiso PET imaging, needs to be confirmed in experimental and clinical studies.     

Establishment of a mammary carcinoma cell line from Syrian hamsters treated with N-methyl-N-nitrosourea

Clearly new breast cancer models are necessary in developing novel therapies. To address this challenge, we examined mammary tumor formation in the Syrian hamster using the chemical carcinogen N-methyl-N-nitrosourea (MNU). A single 50 mg/kg intraperitoneal dose of MNU resulted in a 60% incidence of premalignant mammary lesions, and a 20% incidence of mammary adenocarcinomas. Two cell lines, HMAM4A and HMAM4B, were derived from one of the primary mammary tumors induced by MNU. The morphology of the primary tumor was similar to a high-grade poorly differentiated adenocarcinoma in human breast cancer. The primary tumor stained positively for both HER-2/neu and pancytokeratin, and negatively for both cytokeratin 5/6 and p63. When the HMAM4B cell line was implanted subcutaneously into syngeneic female hamsters, tumors grew at a take rate of 50%. A tumor derived from HMAM4B cells implanted into a syngeneic hamster was further propagated in vitro as a stable cell line HMAM5. The HMAM5 cells grew in female syngeneic hamsters with a 70% take rate of tumor formation. These cells proliferate in vitro, form colonies in soft agar, and are aneuploid with a modal chromosomal number of 74 (the normal chromosome number for Syrian hamster is 44). To determine responsiveness to the estrogen receptor (ER), a cell proliferation assay was examined using increasing concentrations of tamoxifen. Both HMAM5 and human MCF-7 (ER positive) cells showed a similar decrease at 24 h. However, MDA-MB-231 (ER negative) cells were relatively insensitive to any decrease in proliferation from tamoxifen treatment. These results suggest that the HMAM5 cell line was likely derived from a luminal B subtype of mammary tumor. These results also represent characterization of the first mammary tumor cell line available from the Syrian hamster. The HMAM5 cell line is likely to be useful as an immunocompetent model for human breast cancer in developing novel therapies.     

Early assessment of treatment response in patients with AML using [F]FLT PET imaging

Assessment of treatment response in acute leukemia is routinely performed after therapy via bone marrow biopsy. We investigated the use of positron emission tomography (PET) for early assessment of treatment response in patients with acute myeloid leukemia (AML), using the proliferation marker 3′-deoxy-3′-[¹⁸F]fluoro-l-thymidine (FLT). Eight adult AML patients receiving induction chemotherapy underwent whole-body FLT PET/CT scans acquired at different time points during therapy. Patients who entered complete remission (CR) exhibited significantly lower FLT uptake in bone marrow than those patients with resistant disease (RD). In bone marrow, mean and maximum standardized uptake values were 0.8, 3.6 for CR and 1.6, 11.4 for RD, p < 0.001. FLT PET results for CR and RD patients were independent of assessment time point, suggesting that FLT PET scans acquired as early as 2 days after chemotherapy initiation may be predictive of clinical response. This pilot study suggests that FLT PET imaging during induction chemotherapy may serve as an early biomarker of treatment response in AML.     

Prognostic value of SUVmax measurements obtained by FDG-PET in patients with non-small cell lung cancer receiving chemotherapy

[¹⁸F]Fluorodeoxyglucose (FDG) uptake has been shown to correlate well with tumor proliferation rates. In patients with non-small cell lung cancer (NSCLC) receiving chemotherapy, we analyzed the relationships between the maximum standardized uptake value (SUVmax) obtained by FDG positron emission tomography (FDG-PET) and other clinical factors, and examined whether or not SUVmax could predict progression-free survival (PFS) and/or overall survival (OS). This retrospective study involved 62 consecutive NSCLC patients (35 male and 27 female: median age, 65 years). All patients underwent FDG-PET examination before treatment. As the first-line treatment, the patients received chemotherapy with (n = 15) or without (n = 47) radiotherapy. Survival curves were obtained by the Kaplan-Meier method, and differences in survival between subgroups were analyzed by the log-rank test and the Cox proportional hazards model. Significant correlations were observed between SUVmax and gender (P = 0.006), histology (P < 0.001), smoking status (P = 0.049), stage (P = 0.015), and treatment modality (P = 0.008), but not other factors, including age (P = 0.402) and performance status (P = 0.421). The median SUVmax was 5.1 (25-75th percentile: 3.45-7.0) in patients with adenocarcinoma and 8.3 (25-75th percentile: 6.9-9.9) in those with other types of NSCLC. Adenocarcinomas showed significantly lower SUVmax than the other tumor types (P < 0.001). Cox analysis adjusting for possible confounding factors, including gender, smoking status, histology and stage, demonstrated that the hazard ratios increased as the SUVmax increased in terms of both PFS (P = 0.008) and OS (P = 0.045), indicating that SUVmax predicts outcome independently of other clinical factors, such as histology and stage. Our findings indicate that FDG-PET examination can provide information useful for prognostication in NSCLC.