Quality Assurance Considerations in Radiopharmaceutical Therapy Dosimetry Using PLANETDose: An International Atomic Energy Agency Study.

Implementation of radiopharmaceutical therapy dosimetry varies depending on the clinical application, dosimetry protocol, software, and ultimately the operator. Assessing clinical dosimetry accuracy and precision is therefore a challenging task. This work emphasizes some pitfalls encountered during a structured analysis, performed on a single-patient dataset consisting of SPECT/CT images by various participants using a standard protocol and clinically approved commercial software. Methods: The clinical dataset consisted of the dosimetric study of a patient administered with [177Lu]Lu-DOTATATE at Tygerberg Hospital, South Africa, as a part of International Atomic Energy Agency-coordinated research project E23005. SPECT/CT images were acquired at 5 time points postinjection. Patient and calibration images were reconstructed on a workstation, and a calibration factor of 122.6 Bq/count was derived independently and provided to the participants. A standard dosimetric protocol was defined, and PLANETDose (version 3.1.1) software was installed at 9 centers to perform the dosimetry of 3 treatment cycles. The protocol included rigid image registration, segmentation (semimanual for organs, activity threshold for tumors), and dose voxel kernel convolution of activity followed by absorbed dose (AD) rate integration to obtain the ADs. Iterations of the protocol were performed by participants individually and within collective training, the results of which were analyzed for dosimetric variability, as well as for quality assurance and error analysis. Intermediary checkpoints were developed to understand possible sources of variation and to differentiate user error from legitimate user variability. Results: Initial dosimetric results for organs (liver and kidneys) and lesions showed considerable interoperator variability. Not only was the generation of intermediate checkpoints such as total counts, volumes, and activity required, but also activity-to-count ratio, activity concentration, and AD rate-to-activity concentration ratio to determine the source of variability. Conclusion: When the same patient dataset was analyzed using the same dosimetry procedure and software, significant disparities were observed in the results despite multiple sessions of training and feedback. Variations due to human error could be minimized or avoided by performing intensive training sessions, establishing intermediate checkpoints, conducting sanity checks, and cross-validating results across physicists or with standardized datasets. This finding promotes the development of quality assurance in clinical dosimetry.

Epigenomics as Potential Tools for Enhancing Magnitude of Breeding Approaches for Developing Climate Resilient Chickpea.

Epigenomics has become a significant research interest at a time when rapid environmental changes are occurring. Epigenetic mechanisms mainly result from systems like DNA methylation, histone modification, and RNA interference. Epigenetic mechanisms are gaining importance in classical genetics, developmental biology, molecular biology, cancer biology, epidemiology, and evolution. Epigenetic mechanisms play important role in the action and interaction of plant genes during development, and also have an impact on classical plant breeding programs, inclusive of novel variation, single plant heritability, hybrid vigor, plant-environment interactions, stress tolerance, and performance stability. The epigenetics and epigenomics may be significant for crop adaptability and pliability to ambient alterations, directing to the creation of stout climate-resilient elegant crop cultivars. In this review, we have summarized recent progress made in understanding the epigenetic mechanisms in plant responses to biotic and abiotic stresses and have also tried to provide the ways for the efficient utilization of epigenomic mechanisms in developing climate-resilient crop cultivars, especially in chickpea, and other legume crops.

Dosimetric analysis of patients with gastro entero pancreatic neuroendocrine tumors (NETs) treated with PRCRT (peptide receptor chemo radionuclide therapy) using Lu-177 DOTATATE and capecitabine/temozolomide (CAP/TEM).

OBJECTIVE:: Two radiosensitizing chemotherapeutic drugs, capecitabine (CAP) and temozolomide (TEM), are administered concurrently to enhance the therapeutic efficacy of peptide receptor radionuclide therapy (PRRT). This study aims to assess the biodistribution and normal-organ and tumor radiation dosimetry for Lu-177 DOTATATE administered concurrently with CAP/TEM. METHODS:: 20 patients with non-resectable histologically confirmed gastroenteropancreatic neuroendocrine tumors with normal kidney function, a normal haematological profile and somatostatin receptor expression of the tumor lesions, as scintigraphically assessed by a Ga-68 DOTANOC scan, were included in two groups-case group (n = 10) and control group (n = 10). Patients included in case group were those who were advised concomitant CAPTEM therapy by the treating medical oncologist. Patients were administered CAP orally at a dose of 600mg m-2 bovine serum albumin twice a day for 14 days starting 9 days prior to PRRT and oral TEM as a single dose at a dose of 75 mg m-2 was given concurrently for the last 5 days commencing on the day of PRRT (days 9-14). In the control group, patients were treated with Lu-177 DOTATATE only. For PRRT, 6.4 GBq-7.6 GBq (173-207 mCi) of Lu-177 DOTATATE was administered as infusion into each patient over 10-15 min in a solution with positively charged amino acids for renal protection. Dosimetric calculations were done using the HERMES software. RESULTS:: Physiological uptake of Lu-177 DOTATATE was seen in all patients in liver, spleen kidneys, and bone marrow. Radiation absorbed doses (mean ± standard deviation) were obtained as 0.29 ± 0.12 mGy/MBq for kidneys, 0.30 ± 0.18 mGy/MBq for liver, 0.63 ± 0.37 mGy/MBq for spleen, 0.019 ± 0.001 mGy/MBq for bone marrow and 3.85 ± 1.74 mGy/MBq for tumours in the case group and they were 0.31± 0.26, 0.24 ± 0.14, 0.64 ± 0.42, 0.017 ± 0.016, 5.6 ± 11.27 mGy/MBq in kidneys, liver, spleen, bone marrow and neuroendocrine tumour, respectively, in the control group. Mann-Whitney U test between the variables of two groups showed an insignificant difference (p > 0.05). CONCLUSIONS:: The authors demonstrated no significant difference between the tumor and organ doses with Lu-177 DOTATATE in the patients treated with and without concomitant chemotherapy. ADVANCES IN KNOWLEDGE:: To our knowledge, this is the first dedicated study exhibiting dosimetric analysis in patients undergoing PRRT in combination with chemotherapy.

An approach for conjugation of (177) Lu- DOTA-SCN- Rituximab (BioSim) & its evaluation for radioimmunotherapy of relapsed & refractory B-cell non Hodgkins lymphoma patients.

BACKGROUND & OBJECTIVES: The prerequisite of radioimmunotherapy is stable binding of a radionuclide to monoclonal antibodies, which are specific to the tumour-associated antigen. Most B-cell lymphomas express CD20 antigen on the surface of the tumour cells, making it a suitable target for therapeutic radioactive monoclonal antibodies. In the present study, the immunoconjugate of biosimilar Rituximab (Reditux™) and macrocyclic chelator, p-SCN-Bz-DOTA, was prepared and radiolabelled with Lutetium-177 followed by quality control procedures. METHODS: Rituximab(BioSim) was desalted with sodium bicarbonate (0.1M, pH 9.0) and incubated with DOTA-SCN (1:50). The effectiveness of the conjugation was evaluated by determining the number of chelators per antibody molecule. This conjugate was radiolabelled with Lutetium-177 and purified using PD10 column. The quality control parameters like pH, clarity, radiochemical purity, in vitro stability and sterility were studied. Immunoreactivity of 177 Lu-DOTA-Rituximab (BioSim) was assessed using RAMOS cells. The radioimmunoconjugate (RIC) after stringent quality assurance was injected in three patients and the biodistribution profile was analysed. RESULTS: An average of 4.25 ± 1.04 p-SCN-Bz-DOTA molecules could be randomly conjugated to a single molecule of Rituximab (BioSim).The radiochemical purity of the labelled antibody was > 95 per cent with preserved affinity for CD20 antigen. The final preparation was stable up to about 120 h when tested under different conditions. A favourable biodistribution profile was observed with liver showing the maximum uptake of the RIC. INTERPRETATION & CONCLUSIONS: A favourable radiochemical purity, stability and biodistribution of the radiolabelled immunoconjugate indicate that clinical trials for evaluation of toxicity and efficacy of 177 Lu-DOTA-antiCD20 antibody-Rituximab (BioSim) in patients of relapsed and refractory non Hodgkin's lymphoma can be considered.

Dual tracer functional imaging of gastroenteropancreatic neuroendocrine tumors using 68Ga-DOTA-NOC PET-CT and 18F-FDG PET-CT: competitive or complimentary?

OBJECTIVE: This study aimed to compare the diagnostic performance of Ga-DOTANOC PET/CT with F-FDG PET/CT in the patients with gastroenteropancreatic neuroendocrine tumors (GEP-NETs). PATIENTS AND METHODS: Data of 51 patients with definite histological diagnosis of GEP-NET who underwent both Ga-DOTA-NOC PET-CT and F-FDG PET-CT within a span of 15 days were selected for this retrospective analysis. Sensitivity, specificity, and predictive values were calculated for Ga-DOTA-NOC PET-CT and F-FDG PET-CT, and results were compared both on patientwise and regionwise analysis. RESULTS: Ga-DOTA-NOC PET-CT is superior to F-FDG PET-CT on patientwise analysis (P < 0.0001). On regionwise analysis, Ga-DOTA-NOC PET-CT is superior to F-FDG PET-CT only for lymph node metastases (P < 0.003). Although Ga-DOTA-NOC PET-CT detected more liver and skeletal lesions compared with F-FDG PET-CT, the difference was not statistically significant. In addition, the results of combined imaging helped in selecting candidates who would undergo the appropriate mode of treatment, whether octreotide therapy or conventional chemotherapy CONCLUSIONS: Ga-DOTA-NOC PET-CT seems to be superior to F-FDG PET-CT for imaging GEP-NETs. However, their role seems to be complementary because combination of Ga-DOTA-NOC PET-CT and F-FDG PET-CT in such patients helps demonstrate the total disease burden and segregate them to proper therapeutic groups.

Peptide receptor radionuclide therapy with (177)Lu DOTATATE in a case of recurrent carotid body paraganglioma with spinal metastases.

Paragangliomas are rare benign neuroendocrine tumors, and 80% of all paragangliomas are either carotid body tumors or glomus jugulare tumors. We present a case of recurrent unresectable carotid body paraganglioma with nodal and T7 vertebral metastases in a 30-year-old man 6 years postsurgery detected with Ga DOTANOC PET/CT and was administered with peptide receptor radionuclide therapy using Lu DOTATATE. After 5 cycles of Lu DOTATATE (total cumulative activity of 750 mCi [27 GBq]), significant response at the primary site on Ga DOTANOC PET/CT and complete disappearance of nodal and T7 vertebral metastases were noted.

Dosimetric analyses of kidneys, liver, spleen, pituitary gland, and neuroendocrine tumors of patients treated with 177Lu-DOTATATE.

OBJECTIVES: The aim of this work was to calculate the radiation absorbed dose to kidneys, liver, spleen, pituitary gland, and neuroendocrine tumors (NETs) of patients treated with (177)Lu-DOTATATE. METHODS: We enrolled 61 patients (male/female patients, 40/21) with mean age of 48.1 ± 15.3 years affected by different types of NETs diagnosed with (68)Ga-DOTANOC PET-CT and biochemical markers. For radiation protection of kidneys, amino acid mixture (lysine and arginine) was coinfused; 3.7 to 7.4 GBq (100-200 mCi) of (177)Lu-DOTATATE was infused to each patient over 30 minutes. Each patient underwent a series of 9 whole-body scans at 30 minutes (prevoid) and 4, 8, 12, 24, 48, 96, 144, and 168 h. The organs included in dosimetric calculation were kidney, liver, spleen, pituitary gland, and NETs. All dosimetric calculations were done using the OLINDA/EXM 1.0 software. RESULTS: Physiological uptake of (177)Lu-DOTATATE was seen in all patients in kidneys, liver, spleen, and pituitary gland. Radiation absorbed doses were calculated: 0.57 ± 0.09 mGy/MBq for kidneys, 0.27 ± 0.05 mGy/MBq for liver, 1.17 ± 0.14 mGy/MBq for spleen, 0.058 ± 0.011 mGy/MBq for pituitary gland, and 3.41 ± 0.68 mGy/MBq for NETs. CONCLUSIONS: The maximum cumulative activity of (177)Lu-DOTATATE that can be safely administered to a patient within permissible renal threshold in our study was found to be 40 GBq (1100 mCi). However, there are considerable interpatient differences in absorbed doses of all organs requiring individualized dosimetry for optimizing tumor dose.

Role of homocysteine & MTHFR C677T gene polymorphism as risk factors for coronary artery disease in young Indians.

BACKGROUND & OBJECTIVES: Hyperhomocysteinaemia (HCA) either due to mutation of MTHFR gene or deficiency of vitamin B 12 and folic acid, has been reported as a risk factor for coronary artery disease (CAD). The present study was aimed to determine plasma homocysteine (Hcy) levels and to evaluate MTHFR C677T gene polymorphism as risk factors for CAD, and to study the role of Hcy in conjunction with a few other risk factors of CAD in young Indians. The effect of vitamin B12 and folic acid supplements on the raised plasma Hcy levels in patients of CAD was also assessed. METHODS: The present study included 199 consecutive angiography confirmed CAD patients, <45 yr of age, without any other known pro- coagulant state and 200 age- and sex-matched healthy controls. Fasting blood samples were collected in EDTA and plasma Hcy was estimated by ELISA test and the MTHFR C677T polymorphism detection was carried out by PCR-RFLP method. RESULTS: Significant difference (P<0.001) was found between mean fasting levels of plasma Hcy in cases (22.14 ± 10.62 µmol/l) and controls (17.38 ± 8.46 µmol/l) with an Odds ratio as 1.93 (95% CI, 1.27-2.94). Levels of cholesterol, LDL, and triglycerides were significantly (P<0.001) higher in cases compared with controls. INTERPRETATION & CONCLUSIONS: Our study showed significant correlation between hyperhomocysteinaemia and coronary artery disease. Multivariate analysis by logistic regression of the various risk factors of CAD, found high levels of Hcy, cholesterol, LDL and low levels of HDL and smoking as independent predictors of CAD when all other factors were controlled. Significant post-treatment decrease found in HCA was easily modifiable by vitamin intervention irrespective to their CT or TT genotype of C677T MTHFR gene. Further studies to look at the plasma levels of folate and cobalamines and their association with Hcy are required to be done.

The single functional blast resistance gene Pi54 activates a complex defence mechanism in rice.

The Pi54 gene (Pi-k(h)) confers a high degree of resistance to diverse strains of the fungus Magnaporthe oryzae. In order to understand the genome-wide co-expression of genes in the transgenic rice plant Taipei 309 (TP) containing the Pi54 gene, microarray analysis was performed at 72 h post-inoculation of the M. oryzae strain PLP-1. A total of 1154 differentially expressing genes were identified in TP-Pi54 plants. Of these, 587 were up-regulated, whereas 567 genes were found to be down-regulated. 107 genes were found that were exclusively up-regulated and 58 genes that were down- regulated in the case of TP-Pi54. Various defence response genes, such as callose, laccase, PAL, and peroxidase, and genes related to transcription factors like NAC6, Dof zinc finger, MAD box, bZIP, and WRKY were found to be up-regulated in the transgenic line. The enzymatic activities of six plant defence response enzymes, such as peroxidase, polyphenol oxidase, phenylalanine ammonia lyase, ß-glucosidase, ß-1,3-glucanase, and chitinase, were found to be significantly high in TP-Pi54 at different stages of inoculation by M. oryzae. The total phenol content also increased significantly in resistant transgenic plants after pathogen inoculation. This study suggests the activation of defence response and transcription factor-related genes and a higher expression of key enzymes involved in the defence response pathway in the rice line TP-Pi54, thus leading to incompatible host-pathogen interaction.

Immune response to dna vaccine expressing transferrin binding protein a gene of Pasteurella multocida

Haemorrhagic Septicaemia (HS), an acute and fatal disease of cattle and buffalo is primarily caused by serotype B:2 or E:2 of Pasteurella multocida. The transferrin binding protein A (TbpA) has been found to act as immunogen and potent vaccine candidate in various Gram negative bacteria including P. multocida. The present study was carried out to evaluate the potential of this antigen as a DNA vaccine against HS in mice model. The tbpA gene of P. multocida serotype B:2 was cloned in a mammalian expression vector alone and along with murine IL2 gene as immunological adjuvant to produce monocistronic and bicistronic DNA vaccine constructs, respectively. The immune response to DNA vaccines was evaluated based on serum antibody titres and lymphocyte proliferation assay. A significant increase in humoral and cell mediated immune responses was observed in mice vaccinated with DNA vaccines as compared to non immunized group. Additionally, the bicistronic DNA vaccine provided superior immune response and protection level following challenge as compared to monocistronic construct. The study revealed that DNA vaccine presents a promising approach for the prevention of HS.

Radiolabeled somatostatin analogs for radionuclide imaging and therapy in patients with gastroenteropancreatic neuroendocrine tumors.

Gastroenteropancreatic neuroendocrine tumours (GEP-NETs) are a rare type of cancer that can arise from the diffused endocrine system, located in the gastrointestinal (GI) tract (carcinoids) and in the pancreas (insular tumors). Approximately 2% of all malignant tumours of the gastrointestinal system are GEP-NETs which can express somatostatin receptors. 111In-pentetreotide (octreoscan) and 68Ga-DOTA NOC (68Ga-labelled [1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid]-1-Nal3-Octreotide) are the commonly used radiopharmaceuticals for imaging. Once localized using 68Ga DOTA NOC or octreoscan, these tumours can be successfully targeted with radiolabelled somatostatin analogues. This review focuses on common nuclear medicine procedures used in both imaging and treatment of these tumors.