Justification for a Fixed Dose of Eflapegrastim, a Long-Acting G-CSF, in Patients Receiving Docetaxel-Cyclophosphamide Chemotherapy.

Eflapegrastim (Rolontis) is a long-acting granulocyte colony-stimulating factor (G-CSF) produced by conjugating a human G-CSF analogue and a human immunoglobulin G4 Fc fragment, linked via a polyethylene glycol linker. Weight-based doses of 45 to 270 µg/kg eflapegrastim (12.3-73.6 µg/kg as G-CSF) were evaluated in a phase 2 study in patients. Based on these results, a fixed dose of 13.2 mg eflapegrastim (3.6 mg G-CSF) was compared with pegfilgrastim (6 mg G-CSF) in 2 phase 3 studies and in a pharmacokinetic single-arm multicenter study. Absolute neutrophil count (ANC) data from these 3 studies were evaluated in patients with early-stage breast cancer who were treated with docetaxel and cyclophosphamide (n = 669). Serum concentrations of eflapegrastim were determined by enzyme-linked immunosorbent assay. Eflapegrastim systemic exposures were higher in cycle 1 than in cycle 3, likely attributable to the higher ANC in cycle 3, increasing neutrophil-mediated clearance. Eflapegrastim elicited a greater effect on ANC than pegfilgrastim in patients at ∼60% of the G-CSF dose. Body weight had no clinically significant effect on response, justifying administration of a fixed dose of eflapegrastim. The results from 2 phase 3 studies demonstrate that eflapegrastim at a fixed dose of 13.2 mg (3.6 mg G-CSF) administered once per chemotherapy cycle is effective in prophylactic treatment of chemotherapy-induced neutropenia.

Eflapegrastim's enhancement of efficacy compared with pegfilgrastim in neutropenic rats supports potential for same-day dosing.

Eflapegrastim (Rolontis) is a long-acting granulocyte colony-stimulating factor (G-CSF) with an IgG4 Fc fragment and short polyethylene glycol linker. Current G-CSF products are administered 24 hours after chemotherapy. The present study compares the duration of neutropenia (DN) with eflapegrastim or pegfilgrastim at 0, 2, 5, or 24 hours post chemotherapy. Eflapegrastim was evaluated by G-CSF receptor binding and bone marrow cell proliferation assays in vitro. Eflapegrastim-Fc component binding to Fcγ receptors C1q and FcRn was assessed by enzyme-linked immunosorbent assay. Neutropenia was induced in rats via intraperitoneal cyclophosphamide or docetaxel/cyclophosphamide. Rats received chemotherapy followed by vehicle, pegfilgrastim, or eflapegrastim at 2, 5, or 24 hours. The difference in DN after treatment was assessed. In vitro binding to G-CSF receptor of both agents was similar. Binding to FcRn and no binding to Fcγ receptors or C1q were observed with eflapegrastim. Studies in chemotherapy-induced neutropenic rats revealed shorter DN with eflapegrastim versus pegfilgrastim. Increased levels of G-CSF in serum and marrow were observed in groups treated with eflapegrastim versus those treated with pegfilgrastim. Although eflapegrastim and pegfilgrastim have similar in vitro binding affinity, the Fc fragment in eflapegrastim increases the uptake into bone marrow, resulting in increased therapeutic potential for chemotherapy-induced neutropenia. Eflapegrastim's greater marrow resident time provided a pharmacodynamic advantage over pegfilgrastim, translating into shortened duration of neutropenia. Our findings support eflapegrastim same-day administration with chemotherapy, warranting further evaluation in patients undergoing myelosuppressive chemotherapy.

Can we prevent or treat graft-versus-host disease with cellular-therapy?

Acute and chronic graft-versus-host disease (GvHD) are the most important causes of treatment-related morbidity and mortality after allogeneic hematopoietic cell transplants for various diseases. Corticosteroids are an effective therapy in only about one-half of affected individuals and new therapy options are needed. We discuss novel strategies to treat GvHD using cellular-therapy including adoptive transfer of regulatory T-cells (Tregs), mesenchymal stromal cells (MSCs), cells derived from placental tissues, invariant natural killer T-cells (iNKTs), and myeloid-derived suppressor cells (MDSCs).These strategies may be more selective than drugs in modulating GvHD pathophysiology, and may be safer and more effective than conventional pharmacologic therapies. Additionally, these therapies have not been observed to substantially compromise the graft-versus-tumor effect associated with allotransplants. Many of these strategies are effective in animal models but substantial data in humans are lacking.

Regulatable interleukin-12 gene therapy in patients with recurrent high-grade glioma: Results of a phase 1 trial.

Human interleukin-12 (hIL-12) is a cytokine with anticancer activity, but its systemic application is limited by toxic inflammatory responses. We assessed the safety and biological effects of an hIL-12 gene, transcriptionally regulated by an oral activator. A multicenter phase 1 dose-escalation trial (NCT02026271) treated 31 patients undergoing resection of recurrent high-grade glioma. Resection cavity walls were injected (day 0) with a fixed dose of the hIL-12 vector (Ad-RTS-hIL-12). The oral activator for hIL-12, veledimex (VDX), was administered preoperatively (assaying blood-brain barrier penetration) and postoperatively (measuring hIL-12 transcriptional regulation). Cohorts received 10 to 40 mg of VDX before and after Ad-RTS-hIL-12. Dose-related increases in VDX, IL-12, and interferon-γ (IFN-γ) were observed in peripheral blood, with about 40% VDX tumor penetration. Frequency and severity of adverse events, including cytokine release syndrome, correlated with VDX dose, reversing promptly upon discontinuation. VDX (20 mg) had superior drug compliance and 12.7 months median overall survival (mOS) at mean follow-up of 13.1 months. Concurrent corticosteroids negatively affected survival: In patients cumulatively receiving >20 mg versus ≤20 mg of dexamethasone (days 0 to 14), mOS was 6.4 and 16.7 months, respectively, in all patients and 6.4 and 17.8 months, respectively, in the 20-mg VDX cohort. Re-resection in five of five patients with suspected recurrence after Ad-RTS-hIL-12 revealed mostly pseudoprogression with increased tumor-infiltrating lymphocytes producing IFN-γ and programmed cell death protein 1 (PD-1). These inflammatory infiltrates support an immunological antitumor effect of hIL-12. This phase 1 trial showed acceptable tolerability of regulated hIL-12 with encouraging preliminary results.

Clinical utilization of Chimeric Antigen Receptor T-cells (CAR-T) in B-cell acute lymphoblastic leukemia (ALL)-an expert opinion from the European Society for Blood and Marrow Transplantation (EBMT) and the American Society for Blood and Marrow Transplantation (ASBMT).

On August 30, 2017, the U.S. Food and Drug Administration (US-FDA) approved tisagenlecleucel (KYMRIAH, Novartis, Basel, Switzerland), a synthetic bioimmune product of anti-CD19 chimeric antigen receptor-T cells (CAR-T), for the treatment of children and young adults with relapsed/refractory B-cell acute lymphoblastic leukemia (B-ALL). With this new era of personalized cancer immunotherapy, multiple challenges are present ranging from implementation of a CAR-T program to safe delivery of the drug, long-term toxicity monitoring and disease assessments. To address these issues, experts representing the American Society for Blood and Marrow Transplant (ASBMT), the European Group for Blood and Marrow Transplantation (EBMT), the International Society of Cell and Gene Therapy (ISCT), and the Foundation for the Accreditation of Cellular Therapy (FACT), formed a global CAR-T task force to identify and address key questions pertinent for hematologists and transplant physicians regarding the clinical use of anti CD19 CAR-T therapy in patients with B-ALL. This article presents an initial roadmap for navigating common clinical practice scenarios that will become more prevalent now that the first commercially available CAR-T product for B-ALL has been approved.

Clinical Utilization of Chimeric Antigen Receptor T Cells in B Cell Acute Lymphoblastic Leukemia: An Expert Opinion from the European Society for Blood and Marrow Transplantation and the American Society for Blood and Marrow Transplantation.

On August 30, 2017 the US Food and Drug Administration approved tisagenlecleucel (Kymriah; Novartis, Basel, Switzerland), a synthetic bioimmune product of anti-CD19 chimeric antigen receptor T cells (CAR-T), for the treatment of children and young adults with relapsed/refractory B cell acute lymphoblastic leukemia (B-ALL). With this new era of personalized cancer immunotherapy, multiple challenges are present, ranging from implementation of a CAR-T program to safe delivery of the drug, long-term toxicity monitoring, and disease assessments. To address these issues experts representing the American Society for Blood and Marrow Transplant, the European Society for Blood and Marrow Transplantation, the International Society of Cell and Gene Therapy, and the Foundation for the Accreditation of Cellular Therapy formed a global CAR-T task force to identify and address key questions pertinent for hematologists and transplant physicians regarding the clinical use of anti CD19 CAR-T therapy in patients with B-ALL. This article presents an initial roadmap for navigating common clinical practice scenarios that will become more prevalent now that the first commercially available CAR-T product for B-ALL has been approved.

Regulated intratumoral expression of IL-12 using a RheoSwitch Therapeutic System® (RTS®) gene switch as gene therapy for the treatment of glioma.

The purpose of this study was to determine if localized delivery of IL-12 encoded by a replication-incompetent adenoviral vector engineered to express IL-12 via a RheoSwitch Therapeutic System® (RTS®) gene switch (Ad-RTS-IL-12) administered intratumorally which is inducibly controlled by the oral activator veledimex is an effective approach for glioma therapy. Mice bearing 5-10-day-old intracranial GL-261 gliomas were intratumorally administered Ad-RTS-mIL-12 in which IL-12 protein expression is tightly controlled by the activator ligand, veledimex. Local tumor viral vector levels concomitant with veledimex levels, IL-12-mRNA expression, local and systemic cytokine expression, tumor and systemic flow cytometry and overall survival were studied. Ad-RTS-mIL-12+veledimex elicited a dose-related increase in tumor IL-12 mRNA and IL-12 protein and discontinuation of veledimex resulted in a return to baseline levels. These changes correlated with local immune and antitumor responses. Veledimex crossed the blood-brain barrier in both orthotopic GL-261 mice and cynomolgus monkeys. We have demonstrated that this therapy induced localized controlled production of IL-12 which correlates with an increase in tumor-infiltrating lymphocytes (TILs) leading to the desired biologic response of tumor growth inhibition and regression. At day 85 (study termination), 65% of the animals that received veledimex at 10 or 30 mg/m2/day were alive and tumor free. In contrast, the median survival for the other groups were: vehicle 23 days, bevacizumab 20 days, temozolomide 33 days and anti-PD-1 37 days. These findings suggest that the controlled intratumoral production of IL-12 induces local immune cell infiltration and improved survival in glioma, thereby demonstrating that this novel regulated immunotherapeutic approach may be an effective form of therapy for glioma.

Plasma Pharmacokinetics of Veledimex, a Small-Molecule Activator Ligand for a Proprietary Gene Therapy Promoter System, in Healthy Subjects.

Major obstacles to developing effective immunotherapy are the ability of tumors to escape the immune system and the toxicity associated with systemic administration. To overcome these challenges, a gene delivery platform technology, RheoSwitch Therapeutic System (RTS), has been developed to enable the regulated expression of a target gene, Ad-RTS-IL-12, administered intratumorally, where IL-12 expression is controlled via the administration of an oral activator ligand, veledimex. Pharmacokinetics in healthy human subjects indicated that veledimex plasma exposure increased with increasing dose after single- and multiple-dose administration in Labrasol slurry and F-22 capsule formulations. No apparent formulation or sex-related difference in veledimex pharmacokinetics (PK) was observed. Minimal or no plasma accumulation of veledimex was observed after once-daily oral administration for 14 days. Veledimex steady state in plasma was reached after 5 daily doses. Food consumption prior to veledimex administration prolonged and enhanced absorption with no impact on the elimination rate and extent of metabolism of veledimex, resulting in significantly increased systemic exposure to veledimex and its 2 major circulating metabolites. Overall, veledimex was well tolerated and exhibited a PK profile supportive of once-daily dosing. For enhanced efficacy, veledimex should be taken under fed conditions to ensure optimal absorption and sufficient systemic exposure.

Symptom distress predicts long-term health and well-being in allogeneic stem cell transplantation survivors.

The number of survivors after allogeneic hematopoietic stem cell transplantation (HSCT) continues to increase, yet their survivorship experience has not been fully characterized. This study examines the health status and health-related quality of life (HRQL) of HSCT survivors. The aims of the study were to: (1) explore the baseline and change over time in these health outcomes, and (2) characterize subgroups experiencing adverse outcomes. In this longitudinal study, adults who survived >3 years from date of allogeneic HSCT completed a series of patient-reported outcome measures annually, including measures of health status, HRQL, and symptoms. Data were analyzed using hierarchical linear modeling. Subjects (N = 171) were on average 44 (±13.5) years of age and primarily male (62.6%); 40% were Hispanic. Mean scores for physical and mental health and HRQL were preserved relative to population norms. Hierarchical linear modeling revealed no significant change in the mean trajectories of these outcomes, although significant between-individual variability was observed. When controlling for demographic and clinical factors, physical symptom distress negatively affected all outcomes. The impact of symptom distress on physical health varied based on time since HSCT; impairment in physical health was greatest in survivors experiencing high symptom distress and who were within the first decade post transplantation. Extended treatment with systemic immunosuppressive therapy also predicted inferior physical health. These findings suggest that patient-centered outcomes are preserved relative to normative values and are generally stable after allogeneic HSCT, although survivors with persistent symptoms and those receiving systemic immunosuppression experience impairments in health status and HRQL.

First-in-man evaluation of 2 high-affinity PSMA-avid small molecules for imaging prostate cancer.

UNLABELLED: This phase 1 study was performed to determine the pharmacokinetics and ability to visualize prostate cancer in bone, soft-tissue, and the prostate gland using (123)I-MIP-1072 and (123)I-MIP-1095, novel radiolabeled small molecules targeting prostate-specific membrane antigen. METHODS: Seven patients with a documented history of prostate cancer by histopathology or radiologic evidence of metastatic disease were intravenously administered 370 MBq (10 mCi) of (123)I-MIP-1072 and (123)I-MIP-1095 2 wk apart in a crossover trial design. (123)I-MIP-1072 was also studied in 6 healthy volunteers. Whole-body planar and SPECT/CT imaging was performed and pharmacokinetics studied over 2-3 d. Target-to-background ratios were calculated. Absorbed radiation doses were estimated using OLINDA/EXM. RESULTS: (123)I-MIP-1072 and (123)I-MIP-1095 visualized lesions in soft tissue, bone, and the prostate gland within 0.5-1 h after injection, with retention beyond 48 h. Target-to-background ratios from planar images averaged 2:1 at 1 h, 3:1 at 4-24 h, and greater than 10:1 at 4 and 24 h for SPECT/CT. Both agents cleared the blood in a biphasic manner; clearance of (123)I-MIP-1072 was approximately 5 times faster. (123)I-MIP-1072 was excreted in the urine, with 54% and 74% present by 24 and 72 h, respectively. In contrast, only 7% and 20% of (123)I-MIP-1095 had been renally excreted by 24 and 72 h, respectively. Estimated absorbed radiation doses were 0.054 versus 0.110 mGy/MBq for the kidneys and 0.024 versus 0.058 mGy/MBq for the liver, for (123)I-MIP-1072 and (123)I-MIP-1095, respectively. CONCLUSION: (123)I-MIP-1072 and (123)I-MIP-1095 detect lesions in soft tissue, bone, and the prostate gland at as early as 1-4 h. These novel radiolabeled small molecules have excellent pharmacokinetic and pharmacodynamic profiles and warrant further development as diagnostic and potentially when labeled with (131)I therapeutic radiopharmaceuticals.

Comparison of high-specific-activity ultratrace 123/131I-MIBG and carrier-added 123/131I-MIBG on efficacy, pharmacokinetics, and tissue distribution.

Metaiodobenzylguanidine (MIBG) is an enzymatically stable synthetic analog of norepinephrine that when radiolabled with diagnostic ((123)I) or therapeutic ((131)I) isotopes has been shown to concentrate highly in sympathetically innervated tissues such as the heart and neuroendocrine tumors that possesses high levels of norepinephrine transporter (NET). As the transport of MIBG by NET is a saturable event, the specific activity of the preparation may have dramatic effects on both the efficacy and safety of the radiodiagnostic/radiotherapeutic. Using a solid labeling approach (Ultratrace), noncarrier-added radiolabeled MIBG can be efficiently produced. In this study, specific activities of >1200 mCi/micromol for (123)I and >1600 mCi/micromol for (131)I have been achieved. A series of studies were performed to assess the impact of cold carrier MIBG on the tissue distribution of (123/131)I-MIBG in the conscious rat and on cardiovascular parameters in the conscious instrumented dog. The present series of studies demonstrated that the carrier-free Ultratrace MIBG radiolabeled with either (123)I or (131)I exhibited similar tissue distribution to the carrier-added radiolabeled MIBG in all nontarget tissues. In tissues that express NETs, the higher the specific activity of the preparation the greater will be the radiopharmaceutical uptake. This was reflected by greater efficacy in the mouse neuroblastoma SK-N-BE(2c) xenograft model and less appreciable cardiovascular side-effects in dogs when the high-specific-activity radiopharmaceutical was used. The increased uptake and retention of Ultratrace (123/131)I-MIBG may translate into a superior diagnostic and therapeutic potential. Lastly, care must be taken when administering therapeutic doses of the current carrier-added (131)I-MIBG because of its potential to cause adverse cardiovascular side-effects, nausea, and vomiting.

Preclinical evaluation of an 131I-labeled benzamide for targeted radiotherapy of metastatic melanoma.

Radiolabeled benzamides are attractive candidates for targeted radiotherapy of metastatic melanoma as they bind melanin and exhibit high tumor uptake and retention. One such benzamide, N-(2-diethylamino-ethyl)-4-(4-fluoro-benzamido)-5-iodo-2-methoxy-benzamide (MIP-1145), was evaluated for its ability to distinguish melanin-expressing from amelanotic human melanoma cells, and to specifically localize to melanin-containing tumor xenografts. The binding of [(131)I]MIP-1145 to melanoma cells in vitro was melanin dependent, increased over time, and insensitive to mild acid treatment, indicating that it was retained within cells. Cold carrier MIP-1145 did not reduce the binding, consistent with the high capacity of melanin binding of benzamides. In human melanoma xenografts, [(131)I]MIP-1145 exhibited diffuse tissue distribution and washout from all tissues except melanin-expressing tumors. Tumor uptake of 8.82% injected dose per gram (ID/g) was seen at 4 hours postinjection and remained at 5.91% ID/g at 24 hours, with tumor/blood ratios of 25.2 and 197, respectively. Single photon emission computed tomography imaging was consistent with tissue distribution results. The administration of [(131)I]MIP-1145 at 25 MBq or 2.5 GBq/m(2) in single or multiple doses significantly reduced SK-MEL-3 tumor growth, with multiple doses resulting in tumor regression and a durable response for over 125 days. To estimate human dosimetry, gamma camera imaging and pharmacokinetic analysis was performed in cynomolgus monkeys. The melanin-specific binding of [(131)I]MIP-1145 combined with prolonged tumor retention, the ability to significantly inhibit tumor growth, and acceptable projected human dosimetry suggest that it may be effective as a radiotherapeutic pharmaceutical for treating patients with metastatic malignant melanoma.

Preclinical evaluation of novel glutamate-urea-lysine analogues that target prostate-specific membrane antigen as molecular imaging pharmaceuticals for prostate cancer.

Prostate-specific membrane antigen (PSMA) is expressed in normal human prostate epithelium and is highly up-regulated 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)-1carboxy-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 (K(i) = 4.6 +/- 1.6 nmol/L and 0.24 +/- 0.14 nmol/L, respectively) and, when radiolabeled with (123)I, exhibited high affinity for PSMA on human prostate cancer LNCaP cells (K(d) = 3.8 +/- 1.3 nmol/L and 0.81 +/- 0.39 nmol/L, respectively). The association of [(123)I]MIP-1072 and [(123)I]MIP-1095 with PSMA was specific; there was no binding to human prostate cancer PC3 cells, which lack PSMA, and binding was abolished by coincubation with a structurally unrelated NAALADase inhibitor, 2-(phosphonomethyl)pentanedioic acid (PMPA). [(123)I]MIP-1072 and [(123)I]MIP-1095 internalized into LNCaP cells at 37 degrees C. Tissue distribution studies in mice showed 17.3 +/- 6.3% (at 1 hour) and 34.3 +/- 12.7% (at 4 hours) injected dose per gram of LNCaP xenograft tissue, for [(123)I]MIP-1072 and [(123)I]MIP-1095, respectively. [(123)I]MIP-1095 exhibited greater tumor uptake but slower washout from blood and nontarget tissues compared with [(123)I]MIP-1072. Specific binding to PSMA in vivo was shown by competition with PMPA in LNCaP xenografts, and the absence of uptake in PC3 xenografts. The uptake of [(123)I]MIP-1072 and [(123)I]MIP-1095 in tumor-bearing mice was corroborated by single-photon emission computed tomography/computed tomography (SPECT/CT) imaging. PSMA-specific radiopharmaceuticals should provide a novel molecular targeting option for the detection and staging of prostate cancer.

Radiation dosimetry, pharmacokinetics, and safety of ultratrace Iobenguane I-131 in patients with malignant pheochromocytoma/paraganglioma or metastatic carcinoid.

This is a first of many phase 1 study of Ultratrace Iobenguane I-131 (Ultratrace 131I-MIBG; Molecular Insight Pharmaceuticals, Inc., Cambridge, MA). High-specific-activity Ultratrace 131I-MIBG may provide improved efficacy and tolerability over carrier-added 131I-MIBG. We investigated the pharmacokinetics (PK), radiation dosimetry, and clinical safety in 11 patients with confirmed pheochromocytoma/paraganglioma (Pheo) or carcinoid tumors. A single 5.0-mCi (185 MBq) injection of Ultratrace 131I-MIBG, supplemented with 185 microg of unlabeled MIBG to simulate the amount of MIBG anticipated in a therapeutic dose, was administered. Over 120 hours postdose, blood and urine were collected for PK, and sequential whole-body planar imaging was performed. Patients were followed for adverse events for 2 weeks. Ultratrace 131I-MIBG is rapidly cleared from the blood and excreted in urine (80.3% +/- 2.8% of dose at 120 hours). For a therapeutic administration of 500 mCi (18.5 GBq), our estimate of the projected dose is 1.4 Gy for marrow and 10.4 Gy for kidneys. Safety results showed 12 mild adverse events, all considered unrelated to study drug, in 8 of 11 patients. These findings support the further development of Ultratrace 131I-MIBG for the treatment of neuroendocrine tumors, such as metastatic Pheo and carcinoid.

Biomarkers and imaging: physics and chemistry for noninvasive analyses.

The era of 'modern medicine' has changed its name to 'molecular medicine', and reflects a new age based on personalized medicine utilizing molecular biomarkers in the diagnosis, staging and monitoring of therapy. Alzheimer's disease has a classical biomarker determined at autopsy with the histologic staining of amyloid accumulation in the brain. Today we can diagnose Alzheimer's disease using the same classical pathologic biomarker, but now using a noninvasive imaging probe to image the amyloid deposition in a patient and potentially provide treatment strategies and measure their effectiveness. Molecular medicine is the exploitation of biomarkers to detect disease before overt expression of pathology. Physicians can now find, fight and follow disease using imaging, and the need for other disease biomarkers is in high demand. This review will discuss the innovative physical and molecular biomarker probes now being developed for imaging systems and we will introduce the concepts needed for validation and regulatory acceptance of surrogate biomarkers in the detection and treatment of disease.

Synthesis and evaluation of a series of 99mTc(CO)3+ lisinopril complexes for in vivo imaging of angiotensin-converting enzyme expression.

In animal models of cardiac disease and in human congestive heart failure, expression of angiotensin-converting enzyme (ACE) is upregulated in the failing heart and has been associated with disease progression leading to cardiac failure and fibrosis. To develop probes for imaging ACE expression, a series of di(2-pyridylmethyl)amine (D) chelates capable of binding M(CO)3+ (M = technetium, rhenium) was conjugated to lisinopril by acylation of the epsilon-amine of the lysine residue with a series of di(2-pyridylmethylamino)alkanoic acids where the distance of the chelator from the lisinopril core was investigated by varying the number of methylene spacer groups to produce di(2-pyridylmethyl)amine(Cx)lisinopril analogs: D(C4)lisinopril, D(C5)lisinopril, and D(C8)lisinopril. The inhibitory activity of each rhenium complex was evaluated in vitro against purified rabbit lung ACE and was shown to vary directly with the length of the methylene spacer: Re[D(C8)lisinopril], inhibitory concentration of 50% (IC50) = 3 nM; Re[D(C5)lisinopril], IC50 = 144 nM; and Re[D(C4)lisinopril], IC50 = 1,146 nM, as compared with lisinopril, IC50 = 4 nM. The in vivo specificity for ACE was determined by examining the biodistribution of the 99mTc-[D(C8)lisinopril] analog in rats with and without pretreatment with unlabeled lisinopril. Uptake in the lungs, a tissue that constitutively expresses ACE, was 15.2 percentage injected dose per gram at 10 min after injection and was dramatically reduced by pretreatment with lisinopril, supporting ACE-mediated binding in vivo. Planar anterior imaging analysis of 99mTc-[D(C8)lisinopril] corroborated these data. Thus, high-affinity 99mTc-labeled ACE inhibitor has been designed with potency similar to that of lisinopril and has been demonstrated to specifically localize to tissues that express ACE in vivo. This agent may be useful in monitoring ACE as a function of disease progression in relevant diseases such as heart failure.

Development of 17-allylamino-17-demethoxygeldanamycin hydroquinone hydrochloride (IPI-504), an anti-cancer agent directed against Hsp90.

Heat shock protein 90 (Hsp90) is an emerging therapeutic target of interest for the treatment of cancer. Its role in protein homeostasis and the selective chaperoning of key signaling proteins in cancer survival and proliferation pathways has made it an attractive target of small molecule therapeutic intervention. 17-Allylamino-17-demethoxygeldanamycin (17-AAG), the most studied agent directed against Hsp90, suffers from poor physical-chemical properties that limit its clinical potential. Therefore, there exists a need for novel, patient-friendly Hsp90-directed agents for clinical investigation. IPI-504, the highly soluble hydroquinone hydrochloride derivative of 17-AAG, was synthesized as an Hsp90 inhibitor with favorable pharmaceutical properties. Its biochemical and biological activity was profiled in an Hsp90-binding assay, as well as in cancer-cell assays. Furthermore, the metabolic profile of IPI-504 was compared with that of 17-AAG, a geldanamycin analog currently in clinical trials. The anti-tumor activity of IPI-504 was tested as both a single agent as well as in combination with bortezomib in myeloma cell lines and in vivo xenograft models, and the retention of IPI-504 in tumor tissue was determined. In conclusion, IPI-504, a potent inhibitor of Hsp90, is efficacious in cellular and animal models of myeloma. It is synergistically efficacious with the proteasome inhibitor bortezomib and is preferentially retained in tumor tissues relative to plasma. Importantly, it was observed that IPI-504 interconverts with the known agent 17-AAG in vitro and in vivo via an oxidation-reduction equilibrium, and we demonstrate that IPI-504 is the slightly more potent inhibitor of Hsp90.

In vivo molecular imaging of acute and subacute thrombosis using a fibrin-binding magnetic resonance imaging contrast agent.

BACKGROUND: Plaque rupture with subsequent thrombosis is recognized as the underlying pathophysiology of most acute coronary syndromes and stroke. Thus, direct thrombus visualization may be beneficial for both diagnosis and guidance of therapy. We sought to test the feasibility of direct imaging of acute and subacute thrombosis using MRI together with a novel fibrin-binding gadolinium-labeled peptide, EP-1873, in an experimental animal model of plaque rupture and thrombosis. METHODS AND RESULTS: Fifteen male New Zealand White rabbits (weight, approximately 3.5 kg) were made atherosclerotic by feeding a high-cholesterol diet after endothelial aortic injury. Plaque rupture was then induced with the use of Russell's viper venom (RVV) and histamine. Subsequently, MRI of the subrenal aorta was performed before RVV, after RVV, and after EP-1873. Histology was performed on regions suggested by MRI to contain thrombus. Nine rabbits (60%) developed plaque rupture and thrombus, including 25 thrombi visually apparent on MRI as "hot spots" after injection of EP-1873. Histological correlation confirmed all 25 thrombi (100%), with no thrombi seen in the other regions of the aorta. In the remaining 6 rabbits (control) without plaque rupture, no thrombus was observed on the MR images or on histology. CONCLUSIONS: We demonstrate the feasibility of in vivo "molecular" MRI for the detection of acute and subacute thrombosis using a novel fibrin-binding MRI contrast agent in an animal model of atherosclerosis and acute/subacute thrombosis. Potential clinical applications include thrombus detection in acute coronary syndromes and stroke.

90Y and 111In complexes of a DOTA-conjugated integrin alpha v beta 3 receptor antagonist: different but biologically equivalent.

90Y-TA138 is a (90)Y-labeled nonpeptide integrin alpha(v)beta(3) receptor antagonist that binds with high affinity and specificity to integrin alpha(v)beta(3) receptors overexpressed on both endothelial and tumor cells. (90)Y-TA138 has demonstrated significant therapeutic effects in several preclinical tumor-bearing animal models. Since (90)Y is a pure beta-emitter, (111)In-TA138 has been chosen as the imaging surrogate for dosimetry determination of (90)Y-TA138. This report describes the synthesis of (111)In-TA138 and biological evaluations of both (111)In-TA138 and (90)Y-TA138 in the c-neu Oncomouse model. The HPLC data shows that (111)In-TA138 is more hydrophilic with the retention time approximately 4.5 min shorter than that of (90)Y-TA138 under identical chromatographic conditions. Since the only difference between (111)In-TA138 and (90)Y-TA138 is the metal ion, the HPLC retention time difference strongly suggests that indium and yttrium chelates do not share the same coordination sphere in solution even though they are coordinated by the same DOTA conjugate. Despite their differences in lipophilicity and solution structure, biodistribution data in the c-neu Oncomouse model clearly showed that (111)In-TA138 and (90)Y-TA138 are biologically equivalent with respect to their uptake in tumors and other major organs. Therefore, (111)In-TA138 is useful as an imaging surrogate for (90)Y-TA138 and should be able to predict the radiation dosimetry of (90)Y-TA138, a therapeutic radiopharmaceutical for treatment of rapidly growing tumors.