In Vitro Tumor Cell-Binding Assay to Select High-Binding Antibody and Predict Therapy Response for Personalized 64Cu-Intraperitoneal Radioimmunotherapy against Peritoneal Dissemination of Pancreatic Cancer: A Feasibility Study.

Peritoneal dissemination of pancreatic cancer has a poor prognosis. We have reported that intraperitoneal radioimmunotherapy using a 64Cu-labeled antibody (64Cu-ipRIT) is a promising adjuvant therapy option to prevent this complication. To achieve personalized 64Cu-ipRIT, we developed a new in vitro tumor cell-binding assay (64Cu-TuBA) system with a panel containing nine candidate 64Cu-labeled antibodies targeting seven antigens (EGFR, HER2, HER3, TfR, EpCAM, LAT1, and CD98), which are reportedly overexpressed in patients with pancreatic cancer. We investigated the feasibility of 64Cu-TuBA to select the highest-binding antibody for individual cancer cell lines and predict the treatment response in vivo for 64Cu-ipRIT. 64Cu-TuBA was performed using six human pancreatic cancer cell lines. For three cell lines, an in vivo treatment study was performed with 64Cu-ipRIT using high-, middle-, or low-binding antibodies in each peritoneal dissemination mouse model. The high-binding antibodies significantly prolonged survival in each mouse model, while low-and middle-binding antibodies were ineffective. There was a correlation between in vitro cell binding and in vivo therapeutic efficacy. Our findings suggest that 64Cu-TuBA can be used for patient selection to enable personalized 64Cu-ipRIT. Tumor cells isolated from surgically resected tumor tissues would be suitable for analysis with the 64Cu-TuBA system in future clinical studies.

Usefulness of carbon-11-labeled methionine positron-emission tomography for assessing the treatment response of primary central nervous system lymphoma.

BACKGROUND: Primary central nervous system lymphoma (PCNSL) responds relatively quickly to chemotherapy or radiotherapy. However, determination of a complete response after treatment is often difficult because of extremely light residual contrast enhancement on magnetic resonance images due to the effects of microhemorrhages and scar tissue formation. These small enhancing lesions define an unconfirmed complete response. The aim of this study was to investigate the usefulness of carbon-11-labeled methionine (11C-Met) positron-emission tomography (PET) for determining the treatment response of PCNSL. METHODS: Data for 36 patients who were treated for PCNSL between 2011 and 2015 and underwent magnetic resonance imaging and 11C-Met PET were reviewed. Magnetic resonance imaging findings were classified as complete response, unconfirmed complete response, and tumor mass (a composite of partial response, stable disease and progressive disease). PET images were evaluated, standardized uptake values were quantified, and the tumor-to-normal tissue count ratio (TNR) was calculated. Receiver operating characteristic curves were generated to determine the optimal cutoff TNRs. RESULTS: The optimal TNRs for differentiating complete response and unconfirmed complete response from tumor mass were 1.83 (area under the curve, 0.951) and 1.80 (area under the curve, 0.932), respectively. The corresponding sensitivity and specificity values for the diagnosis of tumor mass were 82.4 and 100%, respectively, in the complete response group and 85.3 and 85%, respectively, in the unconfirmed complete response group. CONCLUSIONS: A TNR of ≥1.80 can aid in the detection of active PCNSL using 11C-Met PET. Thus, 11C-Met-PET may be a useful tool for accurate evaluation of the treatment efficacy in PCNSL.

Non-invasive estimation of 10 B-4-borono-L-phenylalanine-derived boron concentration in tumors by PET using 4-borono-2-18 F-fluoro-phenylalanine.

In boron neutron capture therapy (BNCT), 10 B-4-borono-L-phenylalanine (BPA) is commonly used as a 10 B carrier. PET using 4-borono-2-18 F-fluoro-phenylalanine (18 F-FBPA PET) has been performed to estimate boron concentration and predict the therapeutic effects of BNCT; however, the association between tumor uptake of 18 F-FBPA and boron concentration in tumors remains unclear. The present study investigated the transport mechanism of 18 F-FBPA and BPA, and evaluated the utility of 18 F-FBPA PET in predicting boron concentration in tumors. The transporter assay revealed that 2-aminobicyclo-(2.2.1)-heptane-2-carboxylic acid, an inhibitor of the L-type amino acid transporter, significantly inhibited 18 F-FBPA and 14 C-4-borono-L-phenylalanine (14 C-BPA) uptake in FaDu and LN-229 human cancer cells. 18 F-FBPA uptake strongly correlated with 14 C-BPA uptake in 7 human tumor cell lines (r = .93; P < .01). PET experiments demonstrated that tumor uptake of 18 F-FBPA was independent of the administration method, and uptake of 18 F-FBPA by bolus injection correlated well with BPA uptake by continuous intravenous infusion. The results of this study revealed that evaluating tumor uptake of 18 F-FBPA by PET was useful for estimating 10 B concentration in tumors.

Prognosis of patients with peripheral T cell lymphoma who achieve complete response after CHOP/CHOP-like chemotherapy without autologous stem cell transplantation as an initial treatment.

Cyclophosphamide, doxorubicin, vincristine, and prednisolone (CHOP)/CHOP-like chemotherapy has been mostly applied to patients with untreated peripheral T cell lymphoma (PTCL). Because the long-term outcome of patients with PTCL, especially those achieving complete response (CR), has not been fully elucidated, we retrospectively analyzed 78 consecutive patients initially treated with CHOP/CHOP-like chemotherapy, without high-dose chemotherapy followed by autologous stem cell transplantation (HDC/auto-SCT). Median overall and progression-free survivals in all 78 patients were 44 and 17 months, respectively, with a median follow-up of 62 months. In the 53 patients achieving CR, the median relapse-free survival (RFS) was 21 months, and 2-, 3-, and 5-year RFSs were 46, 45, and 36%, respectively. Although our results showed an unfavorable outcome for PTCL as a whole, those who achieved CR following CHOP/CHOP-like chemotherapy did not always have a poor outcome without the consolidation of HDC/auto-SCT; in particular, 45% of the 65 years or younger patients were alive without disease at 5 years.

Radiation absorbed dose estimates for 18F-BPA PET.

Background Boron neutron capture therapy (BNCT) is a molecular radiation therapy approach based on the 10B (n, α) 7Li nuclear reaction in cancer cells. In BNCT, delivery of 10B in the form of 4-borono-phenylalanine conjugated with fructose (BPA-fr) to the cancer cells is important. The PET tracer 4-borono-2-18F-fluoro-phenylalanine (FBPA) has been used to predict the accumulation of BPA-fr before BNCT. Purpose To determine the biodistribution and dosimetric parameters in 18F-BPA PET/CT studies. Material and Methods Human biokinetic data were obtained during clinical 18F-BPA PET studies between February and June 2015 at one institution. Nine consecutive patients were studied prospectively. The internal radiation dose was calculated on the basis of radioactivity data from blood, urine, and normal tissue of the heart, liver, spleen, kidney, and other parts of the body at each time point using OLINDA/EXM1.1 program. We compared our calculations with published 18F-FDG data. Results Adult patients (3 men, 3 women; age range, 28-68 years) had significantly smaller absorbed doses than pediatric patients (3 patients; age range, 5-12 years) ( P = 0.003). The mean effective dose was 57% lower in adult patients compared with pediatric patients. Mean effective doses for 18F-BPA were 25% lower than those for 18F-FDG presented in International Commission of Radiation Protection (ICRP) publication 106. Conclusion We found significant differences in organ absorbed doses for 18F-BPA against those for 18F-FDG presented in ICRP publication 106. Mean effective doses for 18F-BPA were smaller than those for 18F-FDG in the publication by 0.5-38% (mean difference, 25%).

Theragnostic imaging using radiolabeled antibodies and tyrosine kinase inhibitors.

During the past decade, the efficacy of new molecular targeted drugs such as tyrosine kinase inhibitors (TKIs) and monoclonal antibodies has been proven worldwide, and molecular targeted therapies have become the mainstream in cancer therapy. However, clinical use of these new drugs presents unexpected adverse effects or poor therapeutic effects. Therefore, we require diagnostic tools to estimate the target molecule status in cancer tissues and predict therapeutic efficacy and adverse effects. Although immunohistochemical, polymerase chain reaction (PCR) and fluorescence in situ hybridization (FISH) analyses of biopsy samples are conventional and popular for this diagnostic purpose, molecular imaging modalities such as positron emission tomography (PET) and single photon emission computed tomography (SPECT) are also useful for noninvasive estimation of gene and protein expression and drug pharmacokinetics. In this review, we introduce new radiolabeled TKIs, antibodies, and their clinical application in molecular targeted therapy and discuss the issues of these imaging probes.

[Draft guideline regarding appropriate use of 131I-MIBG radiotherapy for neuroendocrine tumors Drafting Committee for Guideline of Radiotherapy with 131I-MIBG, Committee for Nuclear Oncology and Immunology, The Japanese Society of Nuclear Medicine].

131I-MIBG radiotherapy has been used for unresectable nueroendocrine tumors including malignant pheochromocytomas and neuroblastomas in foreign countries since the '80s when clinical therapeutic trials were initiated. In Japan, 131I-MIBG radiotherapy has not been approved by Ministry of Health, Labor and Welfare, however, personally imported 131I-MIBG is now available in limited institutions for therapeutic purpose. This updated guideline draft aims to provide useful information concerning 131I-MIBG radiotherapy, to prevent side effects, and to protect physicians, nurses, other health care professionals, patients and their families from radiation exposure. The committee also provides appendices including practical guidance for attending physicians, patient management and referring physicians for their conveniences.

SMARCA4-deficient tumors in the adrenal gland and small intestines: A rare case report.

Thoracic SMARCA4-deficient undifferentiated tumors (SMARCA4-UTs) are rare undifferentiated thoracic malignancies with poor prognosis. They predominantly affect young men who are heavy smokers. Recently, the category of SMARCA4-deficiency-related malignancy has been expanded to include extra-thoracic sites, such as the paranasal sinuses, gastrointestinal tract, ovary, and uterus. We report a rare case of SMARCA4-deficient tumors in the adrenal gland and small intestines. SMARCA4-deficient tumors should be included in the differential diagnosis when multiple large masses with heterogeneous contrast effect and strong accumulation are seen in cancers of unknown primary on 18F-fluorodeoxyglucose (FDG) positron emission tomography with computed tomography (PET/CT).

A case of pelvic squamous cell carcinoma of unknown primary origin that responded well to radiotherapy and nivolumab.

Squamous cell carcinoma of unknown primary origin in the pelvis is rare. We report a case of a 64-year-old woman with a large osteolytic squamous cell carcinoma of unknown primary origin in the pelvis that presented with p16 expression. The patient presented with leg pain and swelling and was admitted to our hospital. Computed tomography scans of the pelvis revealed a large osteolytic tumor. A computed tomography-guided needle biopsy was performed, and pathological examination revealed neoplastic cells with metastatic squamous cell carcinoma presenting with p16 expression. Despite a whole-body examination, tumor origin remained undetected. The patient was treated for this metastatic squamous cell carcinoma of unknown primary using palliative radiotherapy for hip pain and nivolumab. Remarkable reduction in the tumor marker levels and tumor size were obtained after therapy. Finally, partial remission and progression-free survival for more than 7 months were achieved. In conclusion, we experienced a rare case with a large p16-positive squamous cell carcinoma of unknown primary in pelvis, which responded well to radiotherapy and nivolumab.

Improved synthesis of 17ß-hydroxy-16α-iodo-wortmannin, 17ß-hydroxy-16α-iodoPX866, and the [(131)I] analogue as useful PET tracers for PI3-kinase.

An improved method for the synthesis of 17ß-hydroxy-16α-iodo-wortmannin along with the first synthesis of 17ß-hydroxy-16α-iodoPX866 and [(131)I] radiolabeled 17ß-hydroxy-16α-[(131)I]iodo-wortmannin, as potential PET tracers for PI3K was also described. The differences between wortmannin and its iodo analogue were compared by covalently docking each structure to L833 in PI3K.

SAPHO syndrome with a purely osteolytic form: A case report.

SAPHO (synovitis, acne, pustulosis, hyperostosis, and osteitis) syndrome is a rare, chronic autoinflammatory disorder that can present with a constellation of cutaneous and osteoarticular symptoms. Osteodestructive lesions are not pathognomonic, whereas hyperostosis and osteitis are the most prominent imaging findings. We report the case of a man with osteolytic changes of the lumbar vertebra and a history of palmoplantar pustulosis. Biopsy revealed no neoplasm, suggesting SAPHO syndrome. Our case demonstrates that knowledge of atypical radiologic findings is necessary for the diagnosis of SAPHO syndrome.

Fluorodeoxyglucose positron emission tomography (FDG/PET) shows the effect of carbon-ion radiotherapy (CIRT); with pathologic confirmation.

Response evaluation of carbon-ion radiotherapy poses a diagnostic challenge. Due to its functional aspects, fluorodeoxyglucose positron emission tomography (FDG/PET) has a role in the diagnosis of photon radiation therapy. In addition, several studies suggested that FDG/PET may be useful to select the optimal site for performing a diagnostic biopsy. Here, we report a 73-year-old female in which FDG/PET was effective in determining the recurrence of liposarcoma and the therapeutic effect. Based on the results of FDG/PET, we could make a pathologic definitive diagnosis and selectively performing carbon-ion radiotherapy for active tumors.

Correlation between L-amino acid transporter 1 expression and 4-borono-2-18 F-fluoro-phenylalanine accumulation in humans.

BACKGROUND: The correlation between L-type amino acid transporter 1 (LAT1) expression and 4-borono-2-18 F-fluoro-phenylalanine (18 F-FBPA) accumulation in humans remains unclear. This study aimed to investigate the correlation between LAT1 expression in tumor tissues and 18 F-FBPA accumulation in patients with head and neck cancer who participated in a clinical trial of 18 F-FBPA positron emission tomography (PET). METHODS: Altogether, 28 patients with head and neck cancer who participated in a clinical trial of 18 F-FBPA PET at our institution between March 2012 and January 2018 were included. Correlations between standardized uptake values (SUVs); the maximum SUV (SUVmax ), the mean SUV within a 1 cm3 sphere centered at a single point, that is, the SUVmax (SUVpeak ), the minimum SUV (SUVmin ), and the intensity of LAT1 expression (maximum and minimum LAT1 expressions) were investigated. RESULTS: Weak correlations were identified between SUVmax and LAT1 maximum score, SUVmin and LAT1 maximum score, and SUVmin and LAT1 minimum score (ρ = 0.427, 0.362, and 0.330, respectively). SUVmax and LAT1 minimum score, SUVpeak and LAT1 maximum score, and SUVpeak and LAT1 minimum score demonstrated moderate correlations (ρ = 0.535, 0.556, and 0.661, respectively). Boron neutron capture therapy (BNCT) was performed in 2 of the 4 patients with discrepancies between 18 F-FBPA accumulation and intensity of LAT1 expression, and the intensity of LAT1 expression was a better predictor of treatment response. CONCLUSION: 18 F-FBPA accumulation and the intensity of LAT1 expression demonstrated a moderate correlation; however, LAT1 expression may be a better predictor of treatment response of BNCT in patients with discrepancies.

Process to Remove the Size Variants Contained in the Antibody-Chelator Complex PCTA-NCAB001 for Radiolabeling with Copper-64.

Understanding the physicochemical properties of antibody-drug conjugates is critical to assess their quality at manufacturing and monitor them during subsequent storage. For radiometal-antibody complexes, it is important to control the properties of the antibody-chelator conjugate to maintain the quality of the final product. We have been developing 64Cu-labeled anti-epidermal growth factor receptor antibody NCAB001 (64Cu-NCAB001) for the early diagnosis and therapy of pancreatic cancer with positron-emission tomography. Here, we characterized the larger size variants contained in the antibody-chelator conjugate PCTA-NCAB001 by multi-angle light scattering coupled with size-exclusion chromatography. Secondly, we developed a chromatographic method to remove these size variants. Lastly, we demonstrated the stability of PCTA-NCAB001 after the removal of size variants. Dimer and oligomers were identified in PCTA-NCAB001. These larger size variants, together with some smaller size variants, could be removed by hydrophobic interaction chromatography. The PCTA-NCAB001 product, after the removal of these size variants, could be stored at 4 °C for six months. The methods developed here can be applied to assure the quality of PCTA-NCAB001 and other antibody-drug conjugates to facilitate the development of antibody-radiometal conjugates for positron-emission tomography and radioimmunotherapy of malignant cancers.

Trace Metal Impurities Effects on the Formation of [64Cu]Cu-diacetyl-bis(N4-methylthiosemicarbazone) ([64Cu]Cu-ATSM).

[64Cu]Cu-diacetyl-bis(N4-methylthiosemicarbazone) ([64Cu]Cu-ATSM) is a radioactive hypoxia-targeting therapeutic agent being investigated in clinical trials for malignant brain tumors. For the quality management of [64Cu]Cu-ATSM, understanding trace metal impurities' effects on the chelate formation of 64Cu and ATSM is important. In this study, we conducted coordination chemistry studies on metal-ATSM complexes. First, the effects of nonradioactive metal ions (Cu2+, Ni2+, Zn2+, and Fe2+) on the formation of [64Cu]Cu-ATSM were evaluated. When the amount of Cu2+ or Ni2+ added was 1.2 mol or 288 mol, equivalent to ATSM, the labeling yield of [64Cu]Cu-ATSM fell below 90%. Little effect was observed even when excess amounts of Zn2+ or Fe2+ were added to the ATSM. Second, these metals were reacted with ATSM, and chelate formation was measured using ultraviolet-visible (UV-Vis) absorption spectra. UV-Vis spectra showed a rapid formation of Cu2+ and the ATSM complex upon mixing. The rate of chelate formation by Ni2+ and ATSM was lower than that by Cu-ATSM. Zn2+ and Fe2+ showed much slower reactions with the ATSM than Ni2+. Trace amounts of Ni2+, Zn2+, and Fe2+ showed little effect on [64Cu]Cu-ATSM' quality, while the concentration of impurity Cu2+ must be controlled. These results can provide process management tools for radiopharmaceuticals.

Transitional changes of spacer materials used in carbon-ion radiation therapy.

PURPOSE: To evaluate the imaging findings and transitional changes in spacer materials used in carbon-ion radiation therapy MATERIALS: Medical records were retrospectively reviewed, and the maximum thickness, volume, and CT value of spacers were calculated from CT scans. Procedure-related complications were recorded. RESULTS: A spacer was surgically placed in six patients in retroperitoneal, presacral, or peritoneal sites. The spacer material was polyglycolic acid (PGA) in four patients and expanded polytetrafluoroethylene (ePTFE) in two patients. The thickness of PGA spacers showed no changes in any patients within 4 weeks, but increased within 6 weeks in one patient and was unchanged or decreased in the remaining patients. PGA spacer volume decreased gradually after placement in three of four patients; this was observed at 4 months in two patients and at 6 months in one patient. The mean CT value of PGA spacers was 83 HU just after placement, and decreased gradually thereafter. Air was seen in the PGA spacers of two patients. Neither ePTFE spacer showed volume changes over time, and the mean CT value was low (mean, -53.7 HU) just after placement but increased rapidly to 145 HU at 2 months. CONCLUSION: Spacer imaging findings may vary according to type and may change over time. Familiarity with these features is beneficial for diagnostic radiologists.

Identification and quantitative structure-activity relationship assessment of trace chemical impurities contained in the therapeutic formulation of [64Cu]Cu-ATSM.

BACKGROUND: [64Cu]Cu-diacethyl-bis(N4-methylthiosemicarbazone) ([64Cu]Cu-ATSM) is a radioactive hypoxia-targeting therapeutic agent, and the efficacy and safety of [64Cu]Cu-ATSM in the treatment of malignant brain tumors are evaluated in clinical trials. For the clinical application of [64Cu]Cu-ATSM, we determined a drug formulation incorporating a stabilizer against radiolysis and confirmed its radiochemical stability. This study aimed to identify trace chemical impurities derived from the degradation of ATSM contained in the [64Cu]Cu-ATSM investigational drug formulation and assess their potential hazards by quantitative structure-activity relationship (QSAR) assessment. METHODS: We hypothesized that the chemical impurities contained in the [64Cu]Cu-ATSM formulation were derived from the degradation of ATSM. Therefore, we first identified the degradants of ATSM using LC-MS/MS. ATSM was dissolved with the drug formulation of [64Cu]Cu-ATSM, except for 64Cu, and analyzed by LC-MS/MS at 0 and 48 h after sample preparation. Subsequently, the chemical impurities contained in the [64Cu]Cu-ATSM formulation were measured at 0, 5, and 24 h after preparation by HPLC, and the results were compared to the degradants of ATSM. The potential hazards of the chemical impurities contained in the [64Cu]Cu-ATSM formulation were assessed using the QSAR Toolbox (ver. 4.3). RESULTS: Six ATSM degradants were detected and identified by LC-MS/MS analysis, indicating that the functional groups around the nitrogen and sulfur atoms of ATSM were affected. The same peaks were detected as trace chemical impurities in the [64Cu]Cu-ATSM formulation at 24 h, while no apparent peaks were detected at 0 and 5 h. The estimated LD50 values of these chemical impurities showed 4.31 mg/kg or more by QSAR assessment. In contrast, the estimated amount of each chemical impurity exposed to patients was 31.8 ng/kg or less per dose. The smallest margin between the amount of chemical impurities and smallest estimated LD50 value of the corresponding impurity was a ratio of approximately 1:700,000. CONCLUSIONS: We identified trace chemical impurities derived from ATSM in the [64Cu]Cu-ATSM formulation. This suggests that the potential risk of the systemic exposure of patients to these chemical impurities is substantially low.

Preliminary experiences of PET/MRI in predicting complete response in patients with breast cancer treated with neoadjuvant chemotherapy.

Clinical response predictions through image examinations after neoadjuvant chemotherapy (NAC) for breast cancer is important. The present study aimed to evaluate the utility of a novel imaging modality, positron-emission tomography/magnetic resonance imaging (PET/MRI), in predicting the pathological complete response (pCR) to NAC in patients with early breast cancer. A total of 74 patients underwent PET/MRI, mammography (MG), including tomosynthesis, and ultrasound (US) after NAC. The complete response was predicted using each modality and these outcomes were compared accordingly. In terms of PET/MRI, complete response (CR) was defined as the disappearance of 18F-fluorodeoxyglucose uptake and the absence of enhanced lesions with contrast enhanced MRI. In MG and US, undetectable lesions were considered as CR. The background and tumor characteristics of patients were also analyzed between the pCR and non-pCR cases. Overall, 18 (24.3%) of the 74 patients achieved pCR. The overall sensitivity and specificity of PET/MRI were 72.2 and 78.6%, respectively. Both the sensitivity in hormone receptor (HR)-positive cases and the specificity in HR-negative cases were 100%. HR-negative and human epidermal growth factor receptor 2 (HER2)-positive cases demonstrated a significant association with pCR compared with HR-positive cases and triple negative cases (P=0.017). Furthermore, patients with 'mass' type lesions evaluated by MRI before NAC experienced pCR with a higher frequency than those with 'non-mass' type lesions. There was a statistically significant difference between the two groups (P=0.018). In conclusion, PET/MRI is a different diagnostic approach that utilizes a multi-modality system. It demonstrates reasonable diagnostic accuracies of the responses of NAC with reference to hormonal subtypes in breast cancer.