Clinical application of SPECT-CT with 99mTc-Tektrotyd in bronchial and thymic neuroendocrine tumors (NETs)

Neuroendocrine tumors (NETs) of the thorax including bronchial and thymic tumors belong to foregut NETs. Limited loco-regional thoracic NETs can be resected with surgery, but in extensive metastatic disease the treatment is mainly palliative. A high incidence and density of somatostatin receptors (SSTR2, SSTR3, and SSTR5) are found in thoracic NETs. The purpose of this study was to evaluate the role of SPECT-CT somatostatin receptor scintigraphy (SRS) with 99mTc-Tektrotyd for imaging, staging and follow up of patients with bronchial and thymic neuroendocrine tumors. Forty-one patients with thoracic tumors with neuroendocrine differentiation were studied. Sixty-eight examinations including SPECT-CT studies of the neck and chest and/or abdomen and pelvis were carried out 2–4 hrs. post i.v. administration of aver­age 740 MBq activity dose of 99mTc-EDDA/HYNIC-TOC (Tektrotyd, Polatom). In all 41 investigated patients we obtained 81.25% (13/16), 88% (22/25) and 85.36% (35/41) of sensitivity, specificity and accuracy of this diagnostic approach, respectively. Somatostatin-receptor scintigraphy correctly identified all primary NETs located in the lungs and thymus. SPECT-CT studies with 99mTc-EDDA/HYNIC-TOC resulted in exact pre-surgical and pre-treatment N/M staging of bronchial and thymic NETs, except 2 cases with multiple hepatic metastases and 1 with massive suprarenal metastasis. It can be concluded that SPECT-CT with 99mTc-EDDA/HYNIC-TOC is a valuable tool for staging and follow-up of patients with thoracic NETs

SPECT-CT Imaging with 99mTc-PSMAin Patients with Recurrent Prostate Cancer

Background: Prostate-specific membrane antigen (PSMA) is a cell surface glycoprotein with a large extracellular domain with overexpression of the prostatic tumour cells. Several small molecules of PSMA ligands of inhibitors binding to the active site of PSMA were developed. [99mTc]Tc-PSMA-T4 is a new radiopharmaceutical (Polatom) for imaging loco-regional metastases and/or local relapse in patients with prostate cancer. The purpose of this work was to evaluate the clinical application of SPECT-CT imaging with [99mTc]Tc-PSMA-T4 in patients with recurrent prostate cancer. Material and methods: Thirty-six patients with prostate cancer, aged 60–80 years with biochemical relapse of PSA (ranged from 0.1 to 73 ng/mL) were included. Three patients were studied after tru-cut biopsy, hormonal and cytoreductive radiotherapy and 33 patients out of 36 — after radical treatment (total prostatectomy or definitive radiotherapy of the tumour). All of them underwent whole-body imaging examinations with subsequent target SPECT-CT studies of the pelvis, abdomen and/or chest, 1–3 hrs post i.v. administration of [99mTc]Tc-PSMA-T4. The average activity dose was 6.3 MBq/kg in a man of 70 kg. A Dual-head SPECT-CT gamma camera with a low dose CT scan (Symbia T2, Siemens) was used. The images were interpreted based on all other clinical and radiological data. Follow-up could be conducted in 11/36 patients during that period. Results: Normal biodistribution of the radiopharmaceutical with high activity background was observed in the liver, spleen, kidneys, lacrimal and salivary glands, bowels and urinary bladder. Positive imaging for local relapse in the prostate bad was imaged in 21 patients, lymph node metastases — in 16 cases, bone lesions — in 10 cases, pulmonary metastases – in 2 cases, hepatic lesions were visualised in one of them and in another — adrenal suprarenal metastasis with intensive tracer uptake significant for overexpression of PSMA. There was a suspicion for local recurrences in 4 patients with negative MRT studies who were followed up. In 3 cases, previously treated bone metastases were partially negative without tracer uptake, only some progressive bone lesions were positive. Five patients were with negative results. Sensitivity was 84.37% (27/32), specificity — 100% (4/4) and accuracy — 86.11% (31/36). Conclusions: In conclusion SPECT-CT imaging with [99mTc]Tc-PSMA-T4 could be applied in patients with prostate cancer for the diagnosis of recurrent disease to determine personalized treatment for each patient. Specific uptake of this tracer, depicted by SPECT-CT images has clinical importance of identifying and assessing PSMA expression before consideration of Radio Ligand Therapy (RLT) with [177Lu]Lu-PSMA. SPECT-CT imaging with [99mTc]PSMA is promising and reliable nuclear medicine approach to monitoring therapeutic effect after treatment and for restaging of the disease.Introduction: Prostate-specific membrane antigen (PSMA) is a cell surface glycoprotein with a large extracellular domain with overexpression of the prostatic tumor cells. A lot of small molecules of PSMA ligands or inhibitors binding to active site of PSMA were developed. 99mTc-PSMA is a new radiopharmaceutical (Polatom) for imaging of loco-regional metastases and/or local relapse in patients with prostate cancer. The purpose of this work was to evaluate clinical application of SPECT-CT imaging with 99mTc-PSMAinpatients with recurrent prostate cancer. Patientsand Methods: Thirty-six patients with prostate cancer, aged 60-80 years with biochemical relapse of PSA (ranged from 0.1 to 73ng/ml) were included. Three patients were studied after tru-cut biopsy, hormonal and cytoreductive radiotherapy and 33 patients out of 36 – after radical treatment (total prostatectomy or definitive radiotherapy of the tumor). All of them underwent whole-body imaging examinations with subsequent target SPECT-CT studies of the pelvis, abdomen and/or chest, 1–3 hrs post i.v. administration of 99mTc-PSMA. The average activity dose was 6.3MBq/kg in a manof 70 kg. Dual-head SPECT-CT gamma camera with low dose CT scan Symbia T2, Siemens) was used. The images were interpreted based on all other clinical and radiological data. Follow-up could be conducted in 11/36 patients during that period. Results: Normal biodistribution of the radiopharmaceutical with high activity background was observed in the liver, spleen, kidneys, lacrimal and salivary glands, bowels and urinary bladder.Positive imaging for local relapse in the prostate bad was imaged in 21 patients, lymph node metastases – in 16 cases, bone lesions – in 10 cases, pulmonary metastases – in 2 cases, hepatic lesions were visualised in one of them and in another - adrenal suprarenal metastasis with intensive tracer uptake significant for overexpression of PSMA. There was suspicious for local recurrencesin 4 patients with negative MRT studies who were followed-up.  In 3 cases, previously treated bone metastases  were partially negativewithout tracer uptake,only some progressive bone lesions were positive.Five patientswerewith negative results. Sensitivity was 84,37% (27/32), specificity – 100% (4/4) and accuracy – 86,11% (31/36). Conclusion: In conclusion SPECT-CT imaging with 99mTc-PSMA could be applied in patients with prostate cancer for the diagnosis of recurrent disease in order to determine personalized treatment for each individual patient. Specific uptake of this racer, depicted by SPECT-CT images has clinical importance of identifying and assessment  PSMA expression before consideration of Radio Ligand Therapy (RLT) with 177Lu-PSMA.SPECT-CT imaging with 99mTc-PSMA is promising and reliable nuclear medicine approach to monitor therapeutic effect after treatment and for restaging of the disease

Highly efficient selenomethionine labeling of recombinant proteins produced in mammalian cells

Abstract The advent of the multiwavelength anomalousdiffraction phasing methodhas significantlyacceleratedcrystal structuredeterminationand hasbecomethe norm in protein crystallography. This method allowsresearchersto takeadvantageofthe anomalous signal fromdivers eatoms,but thedominantmethod forderivativ epreparation is selenomethionine substitution.S everal generallya pplicable, high-efficiency labeling protocolsh aveb een developed for use in the bacterial, yeast, andbaculovirus/insect cell expressionsystems butnot formammalian tissuec ulture.A sal arge number of proteinso fb iomedical importance cano nlyb ep roducedi ny ields sufficient forX -ray diffraction experimentsi nm ammalian expression systems, it becomesa ll them ore importantt od evelops uchp rotocols.W et herefore evaluateds everal variablest hatp lay roles in determining incorporation levels andr eporth ere as imple protocolf or selenom ethionine modification of proteinsi n mammalian cellsr outinely yielding >90%l abeling efficiency. Keywords: proteinl abeling; proteinc rystallography; selenomethionine; multiplew avelength anomalous diffraction; mammalian cell culture The multiwavelength anomalous diffraction (MAD)phasingm ethod (Hendrickson1 991) hasb ecome them ethod of choice for X-ray phase determination, with >50% of thee xperimentally phased structures deposited in the PDB during thep asty ear beingd etermined by MAD. WhileM AD has allowed researchers to take advantage of thea nomalouss ignal from several diverse heavy atoms, thed ominantm ethodf or heavya tomd erivative preparation is selenomethioninesubstitution. Several factors contribute to the widespread use of selenomethionine substitution, including simplicity, adaptabilitytodifferent expression systems, scalability,a nd, in some cases, an almost quantitative replacement of methionine resulting in ahomogeneousprotein population. This method results in modified proteins withoutsignificantstructural perturbations due to heavy atom incorporation,w hile eliminatingthe difficult and time-consuming screenings forheavy atom derivatives. It is estimated that, foras uccessful MADe xperiment, ones elenomethionine residue is required for every ; 75-100a mino acids (Hendrickson andO gata 1997). This corresponds to ; 80%o fa ll proteins, which have am ethioninecontentof1%ormore (Strub et al.2003). There are twol imitations to the method: First, the calculations abovea ssumeq uantitative( or near-quantitative) methionine substitution, which often is not the case.F or example, as the complexity of the expression system host increases, so does the complexity of the media requiredfor their growth, Article published onlinea head of print. Articlea nd publication date are at http://www.proteinscience.org/cg