HER2/neu is over expressed in 20-25% of breast cancers. HER2 breast cancers are aggressive and are associated with poor prognosis. The aim of this study was to develop the clinical grade Lu-177-trastuzumab and its preliminary evaluation for specific tumor targeting in HER2 positive breast cancer patients. Trastuzumab was conjugated to bifunctional chelator, DOTA, and characterized for integrity and the number of molecules conjugated. Radiolabeling of DOTA-conjugated trastuzumab was optimized using Lu-177. Quality control parameters including radiochemical purity, stability, sterility, pyrogenicity and immunoreactivity were assessed. A preliminary pilot study was conducted on breast cancer patients (n = 6 HER2 positive and n = 4 HER2 negative) to evaluate the ability of Lu-177-trastuzumab for HER2 specific tumor targeting. The conjugates were efficiently labeled with Lu-177 with high radiochemical purity (up to 91%) and specific activity (6-13 µCi/µg). Lu-177-trastuzumab was stable up to 12 hr post labeling. The radioimmunoassay demonstrated good antigen binding ability and specificity for HER2 receptor protein. The patient studies showed the localization of Lu-177-trastuzumab at primary as well as metastatic sites (HER2 positive) in the planar and SPECT/CT images. No tracer uptake was observed in HER2 negative patients that indicated the specificity of Lu-177-trastuzumab. The study demonstrated that in-house developed Lu-177-trastuzumab has specific targeting ability for HER2 expressing lesions and may in future become a palliative treatment option in the form of targeted radionuclide therapy for disseminated HER2 positive breast cancer.

The present study is aimed at carrying out a comparative performance evaluation of different types of (68)Ge/(68)Ga generators to identify the best choice for use in (68)Ga-radiopharmacy. Over the 1 year period of evaluation, the elution yields from the CeO2-based and SiO2-based (68)Ge/(68) Ga generators remained almost consistent, in contrast to the sharp decrease observed in the elution yields from TiO2 and SnO2-based generators. The level of (68)Ge impurity in (68)Ga eluates from the CeO2 and SiO2-based (68)Ge/(68)Ga generator was always <10(-3)%, while this level increased from 10(-3)% to 10(-1)% in case of TiO2 and SnO2-based generators. The level of chemical impurities in (68)Ga eluates from CeO2 and SiO2-based (68)Ge/(68)Ga generators was negligibly low (<0.1 ppm) in contrast to the significantly higher level (1-20 ppm) of such impurities in eluates from other two generators. As demonstrated by radiolabeling studies carried out using DOTA-coupled dimeric cyclic RGD peptide derivative (DOTA-RGD2), CeO2-PAN and SiO2-based generators are directly amenable for radiopharmaceutical preparation, whereas the other generators can be only used after post-elution purification of (68)Ga eluates. Clinically relevant dose of (68)Ga-DOTA-RGD2 was prepared in a hospital radiopharmacy for non-invasive visualization of tumors in breast cancer patients using positron emission tomography.

Background Corticotrophin releasing hormone (CRH) is the major regulator of ACTH secretion from the anterior pituitary and acts via CRH-1 receptors (CRH-1R). Corticotropinoma though autonomous still retain their responsiveness to CRH and hence, we hypothesize that in vivo detection of CRH-1 receptors on pituitary adenoma using Gallium-68 ( 68Ga) tagged CRH can indicate the functionality of adenoma and combining it with Positron emission tomography-computed tomography (PET-CT) can provide requisite anatomical information. Methods Subjects with ACTH dependent Cushing's syndrome (CS) [n = 27, 24: Cushing's disease (CD), 3: ectopic Cushing's syndrome (ECS)] underwent 68Ga CRH PET-CT. Two nuclear medicine physicians read these images for adenoma delineation and superimposed them on MRI sella. The information so provided was used for intra-operative navigation and compared with operative and histopathological findings. Findings 68Ga CRH PET-CT correctly delineated corticotropinoma in all the 24 cases of CD, including the ten cases with size &lt; 6mm (four cases negative on MRI). Corticotropinoma location on 68Ga CRH PET fusion images with MRI were concordant with operative findings and further confirmed on histopathology. There was no tracer uptake in pituitary in two patients with ECS while in another, the diffuse uptake in pituitary suggested ectopic CRH production. Conclusion 68Ga CRH PET-CT represents a novel non-invasive molecular imaging targeting CRH receptors that not only delineates corticotropinoma and provides surgeon with valuable information for intra-operative tumour navigation but also helps in differentiating pituitary from extra-pituitary source of ACTH dependent Cushing’s syndrome.

Purpose of the Study:To study quality control parameters of routinely prepared positron emission tomography (PET) radiopharmaceuticals.Materials and Methods:Three PET radiopharmaceuticals fluorine-18 fluorodeoxyglucose (F-18 FDG), N-13 ammonia (N-13 NH3), and Ga-68 DOTATATE (n = 25 each), prepared by standardized protocols were used. The radionuclide purity, radiochemical purity, residual solvents, pH, endotoxins, and sterility of these radiopharmaceuticals were determined.Results:The physical half-life of radionuclide in radiopharmaceuticals, determined by both graphical and formula method, demonstrated purity of radionuclides used. pH of all PET radiopharmaceuticals used was in the range of 5-6.5. No microbial growth was observed in radiopharmaceutical preparations. The residual solvents, chemical impurity, and pyrogens were within the permissible limits.Conclusions:All three PET radiopharmaceuticals were safe for intravenous administration.

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