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IntroductionSince the prostate-specific membrane antigen (PSMA) is frequently over-expressed in prostate cancer (PCa) several PSMA-targeting molecules are under development to detect and treat metastatic castration resistant prostate cancer (mCRPC). We investigated the tissue kinetics of a small molecule inhibitor of PSMA ((S)-2-(3-((S)-1-carboxy-5-(3-(4-[124I]iodophenyl)ureido)pentyl)ureido)pentanedioicacid; MIP-1095) using PET/CT to estimate radiation dosimetry for the potential therapeutic use of 131I-MIP-1095 in men with mCRPC. We also report preliminary safety and efficacy of the first 28 consecutive patients treated under a compassionate-use protocol with a single cycle of 131I-MIP-1095.MethodsSixteen patients with known prostate cancer underwent PET/CT imaging after i.v. administration of 124I-MIP-1095 (mean activity: 67.4 MBq). Each patient was scanned using PET/CT up to five times at 1, 4, 24, 48 and 72 h post injection. Volumes of interest were defined for tumor lesions and normal organs at each time point followed by dose calculations using the OLINDA/EXM software. Twenty-eight men with mCRPC were treated with a single cycle of 131I-MIP-1095 (mean activity: 4.8 GBq, range 2 to 7.2 GBq) and followed for safety and efficacy. Baseline and follow up examinations included a complete blood count, liver and kidney function tests, and measurement of serum PSA.ResultsI-124-MIP-1095 PET/CT images showed excellent tumor uptake and moderate uptake in liver, proximal intestine and within a few hours post-injection also in the kidneys. High uptake values were observed only in salivary and lacrimal glands. Dosimetry estimates for I-131-MIP-1095 revealed that the highest absorbed doses were delivered to the salivary glands (3.8 mSv/MBq, liver (1.7 mSv/MBq) and kidneys (1.4 mSv/MBq). The absorbed dose calculated for the red marrow was 0.37 mSv/MBq. PSA values decreased by >50 % in 60.7 % of the men treated. Of men with bone pain, 84.6 % showed complete or moderate reduction in pain. Hematological toxicities were mild. Of men treated, 25 % had a transient slight to moderate dry mouth. No adverse effects on renal function were observed.ConclusionBased on the biodistribution and dose calculations of the PSMA-targeted small molecule 124I-MIP-1095 therapy with the authentic analog 131I-MIP-1095 enables a targeted tumor therapy with unprecedented doses delivered to the tumor lesions. Involved lymph node and bone metastases were exposed to estimated absorbed doses upwards of 300 Gy.Electronic supplementary materialThe online version of this article (doi:10.1007/s00259-014-2713-y) contains supplementary material, which is available to authorized users.

Prostate-specific membrane antigen (PSMA) is expressed in normal human prostate epithelium and is highly upregulated in prostate cancer. We previously reported a series of novel small molecule inhibitors targeting PSMA. Two compounds, MIP-1072, (S)-2-(3-((S)-1-carboxy-5-(4–iodobenzylamino)pentyl)ureido)pentanedioic acid and MIP-1095, (S)-2-(3-((S)-1-carboxy-5-(3-(4-iodophenyl)ureido)pentyl)ureido)pentanedioic acid, were selected for further evaluation. MIP-1072 and MIP-1095 potently inhibited the glutamate carboxypeptidase activity of PSMA (Ki = 4.6 ± 1.6 and 0.24 ± 0.14 nM, respectively), and when radiolabeled with 123I exhibited high affinity for PSMA on human prostate cancer LNCaP cells (Kd = 3.8 ± 1.3 and 0.81 ± 0.39 nM, respectively). The association of [123I]MIP-1072 and [123I]MIP-1095 with PSMA was specific; there was no binding to human prostate cancer PC3 cells, which lack PSMA, and binding was abolished by co-incubation with a structurally unrelated NAALADase inhibitor, 2-(phosphonomethyl)pentanedioic acid (PMPA). [123I]MIP-1072 and [123I]MIP-1095 internalized into LNCaP cells at 37 °C. Tissue distribution studies in mice demonstrated 17.3 ± 6.3 (at 1 hr) and 34.3 ± 12.7 (at 4 hr) % injected dose per gram of tissue, for [123I]MIP-1072 and [123I]MIP-1095, respectively. [123I]MIP-1095 exhibited greater tumor uptake but slower washout from blood and non-target tissues compared to [123I]MIP-1072. Specific binding to PSMA in vivo was demonstrated by competition with PMPA in LNCaP xenografts, and the absence of uptake in PC3 xenografts. The uptake of [123I]MIP-1072 and [123I]MIP-1095 in tumor bearing mice was corroborated by SPECT/CT imaging. PSMA-specific radiopharmaceuticals should provide a novel molecular targeting option for the detection and staging of prostate cancer.

Endosomal sequestration of lipid-based nanoparticles (LNPs) remains a formidable barrier to delivery. Herein, structure-activity analysis of cholesterol analogues reveals that incorporation of C-24 alkyl phytosterols into LNPs (eLNPs) enhances gene transfection and the length of alkyl tail, flexibility of sterol ring and polarity due to-OH group is required to maintain high transfection. Cryo-TEM displays a polyhedral shape for eLNPs compared to spherical LNPs, while x-ray scattering shows little disparity in internal structure. eLNPs exhibit higher cellular uptake and retention, potentially leading to a steady release from the endosomes over time. 3D single-particle tracking shows enhanced intracellular diffusivity of eLNPs relative to LNPs, suggesting eLNP traffic to productive pathways for escape. Our findings show the importance of cholesterol in subcellular transport of LNPs carrying mRNA and emphasize the need for greater insights into surface composition and structural properties of nanoparticles, and their subcellular interactions which enable designs to improve endosomal escape.

Prostate specific membrane antigen (PSMA) is a validated molecular marker for prostate cancer. A series of glutamate-urea (Glu-urea-X) heterodimeric inhibitors of PSMA were designed and synthesized where X = epsilon-N-(o-I, m-I, p-I, p-Br, o-Cl, m-Cl, p-Cl, p-F, H)-benzyl-Lys and epsilon-(p-I, p-Br, p-Cl, p-F, H)-phenylureido-Lys. The affinities for PSMA were determined by screening in a competitive binding assay. PSMA binding of the benzyllysine series was significantly affected by the nature of the halogen substituent (IC(50) values, Cl < I = Br << F = H) and the ring position of the halogen atom (IC(50) values, p-I < o-I << m-I). The halogen atom had little affect on the binding affinity in the para substituted phenylureido-Lys series. Two lead iodine compounds were radiolabeled with (123)I and (131)I and demonstrated specific PSMA binding on human prostate cancer cells, warranting evaluation as radioligands for the detection, staging, and monitoring of prostate cancer.

2؉-stimulated phosphorylation of phosphatidylinositol in intact cells. These data demonstrate a novel mechanism for modulating phosphatidylinositol 3-kinase and provide a direct link between components of two fundamental signaling pathways.A critical aspect of protein and/or lipid kinase regulation is the tight coupling of catalytic activity to various extracellular or intracellular signals. Alterations in levels of intracellular free Ca 2ϩ ([Ca 2ϩ ] i ) 1 mediate the action of several hormones through the regulation of key enzymes; these signaling events are often orchestrated by the Ca 2ϩ effector, calmodulin (CaM) (1). Activation of phosphatidylinositol 3-kinase (PI3-kinase) in many tissues and cell types is required for mitogenesis, neuronal differentiation, and enhanced glucose transport (2). PI3-kinase and CaM are common components of several fundamental intracellular processes. For example, wortmannin, an inhibitor of PI3-kinase, and CGS9343B impede insulin-induced glucose uptake (3-5). Both CaM (6, 7) and PI3-kinase (8) participate in early endosome fusion. In the cytoskeleton, PI3-kinase has been linked to actin rearrangement (9), binds ␣-, ␤-and ␥-tubulin (10), and plays a role in platelet-derived growth factor-and insulin-induced membrane ruffling (11,12). Overexpression of CaM alters cell morphology and the arrangement of microfilaments within the cell (13). In addition, CaM binds to a variety of cytoskeletal proteins (1) including the family of unconventional myosins (14) and has been implicated in osteoclast membrane ruffling (15) and the formation of microspikes in neuronal cells (16). Finally, both PI3-kinase (17) and CaM, via modulation of the association of IQGAP1 with Cdc42 (18), may participate in the regulation of Rho family GTPases. Since CaM and PI3-kinase modulate similar cellular events, we evaluated a possible interaction between these two signaling components. EXPERIMENTAL PROCEDURESCell Culture and Lysis-Sf9 cells were maintained in Grace's medium supplemented with 10% fetal bovine serum and infected with baculovirus as described previously (19). CHO cells were grown to 80% confluence in Ham's F-12 medium with 10% fetal bovine serum. 32D cells and 32D cells expressing rat IRS-1 (32D/IRS-1) were cultured as described previously (20). The medium was removed, cells were washed 3 times with phosphate-buffered saline, and 1 ml of lysis buffer (50 mM Tris base, pH 7.4, 150 mM NaCl, 1 mM sodium orthovanadate, 1 mM phenylmethylsulfonyl fluoride, 0.1 g/ml leupeptin, aprotonin, and pepstatin, and 1% Triton X-100) was added. Where indicated CaCl 2 or EGTA was included. The cells were collected and quick-frozen in methanol/dry CO 2 .Antibodies-The specific anti-calmodulin monoclonal antibody has been previously described (21). The anti-myoglobin monoclonal antibody (IgG 1 ) was highly purified by Dr. J. Ladenson (Washington University Medical Center, St. Louis). The anti-p85 antibody was prepared by immunizing rabbits with a glutathione S-transferase (GST) fusion protein containing the inter...

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Messenger RNA (mRNA) represents an attractive therapeutic modality for potentially a wide range of clinical indications but requires uridine chemistry modification and/or tuning of the production process to prevent activation of cellular innate immune sensors and a concomitant reduction in protein expression. To decipher the relative contributions of these factors on immune activation, here, we compared, in multiple cell and in vivo models, mRNA that encodes human erythropoietin incorporating either canonical uridine or N1-methyl-pseudouridine (1mΨ), synthesized by either a standard process shown to have double-stranded RNA (dsRNA) impurities or a modified process that yields a highly purified mRNA preparation. Our data demonstrate that the lowest stimulation of immune endpoints was with 1mΨ made by the modified process, while mRNA containing canonical uridine was immunostimulatory regardless of process. These findings confirm that uridine modification and the reduction of dsRNA impurities are both necessary and sufficient at controlling the immune-activating profile of therapeutic mRNA.