Imaging the Met Receptor Tyrosine Kinase (Met) and Assessing Tumor Responses to a Met Tyrosine Kinase Inhibitor in Human Xenograft Mouse Models with a [99mTc] (AH-113018) or Cy 5** (AH-112543) Labeled Peptide.

Developing an imaging agent targeting the hepatocyte growth factor receptor protein (Met) status of cancerous lesions would aid in the diagnosis and monitoring of Met-targeted tyrosine kinase inhibitors (TKIs). A peptide targeting Met labeled with [(99m)Tc] had high affinity in vitro (Kd = 3.3 nM) and detected relative changes in Met in human cancer cell lines. In vivo [(99m)Tc]-Met peptide (AH-113018) was retained in Met-expressing tumors, and high-expressing Met tumors (MKN-45) were easily visualized and quantitated using single-photon emission computed tomography or optical imaging. In further studies, MKN-45 mouse xenografts treated with PHA 665752 (Met TKI) or vehicle were monitored weekly for tumor responses by [(99m)Tc]-Met peptide imaging and measurement of tumor volumes. Tumor uptake of [(99m)Tc]-Met peptide was significantly decreased as early as 1 week after PHA 665752 treatment, corresponding to decreases in tumor volumes. These results were comparable to Cy5**-Met peptide (AH-112543) fluorescence imaging using the same treatment model. [(99m)Tc] or Cy5**-Met peptide tumor uptake was further validated by histologic (necrosis, apoptosis) and immunoassay (total Met, p Met, and plasma shed Met) assessments in imaged and nonimaged cohorts. These data suggest that [(99m)Tc] or Cy5**-Met peptide imaging may have clinical diagnostic, prognostic, and therapeutic monitoring applications.

Immuno-PET imaging of tumor endothelial marker 8 (TEM8).

Tumor endothelial marker 8 (TEM8) is a cell surface receptor that is highly expressed in a variety of human tumors and promotes tumor angiogenesis and cell growth. Antibodies targeting TEM8 block tumor angiogenesis in a manner distinct from the VEGF receptor pathway. Development of a TEM8 imaging agent could aid in patient selection for specific antiangiogenic therapies and for response monitoring. In these studies, L2, a therapeutic anti-TEM8 monoclonal IgG antibody (L2mAb), was labeled with (89)Zr and evaluated in vitro and in vivo in TEM8 expressing cells and mouse xenografts (NCI-H460, DLD-1) as a potential TEM8 immuno-PET imaging agent. (89)Zr-df-L2mAb was synthesized using a desferioxamine-L2mAb conjugate (df-L2mAb); (125)I-L2mAb was labeled directly. In vitro binding studies were performed using human derived cell lines with high, moderate, and low/undetectable TEM8 expression. (89)Zr-df-L2mAb in vitro autoradiography studies and CD31 IHC staining were performed with cryosections from human tumor xenografts (NCI-H460, DLD-1, MKN-45, U87-MG, T-47D, and A-431). Confirmatory TEM8 Western blots were performed with the same tumor types and cells. (89)Zr-df-L2mAb biodistribution and PET imaging studies were performed in NCI-H460 and DLD-1 xenografts in nude mice. (125)I-L2mAb and (89)Zr-df-L2mAb exhibited specific and high affinity binding to TEM8 that was consistent with TEM8 expression levels. In NCI-H460 and DLD-1 mouse xenografts nontarget tissue uptake of (89)Zr-df-L2mAb was similar; the liver and spleen exhibited the highest uptake at all time points. (89)Zr-L2mAb was highly retained in NCI-H460 tumors with <10% losses from day 1 to day 3 with the highest tumor to muscle ratios (T:M) occurring at day 3. DLD-1 tumors exhibited similar pharmacokinetics, but tumor uptake and T:M ratios were reduced ∼2-fold in comparison to NCI-H460 at all time points. NCI-H460 and DLD-1 tumors were easily visualized in PET imaging studies despite low in vitro TEM8 expression in DLD-1 cells indicating that in vivo expression might be higher in DLD-1 tumors. From in vitro autoradiography studies (89)Zr-df-L2mAb specific binding was found in 6 tumor types (U87-MG, NCI-H460, T-47D MKN-45, A-431, and DLD-1) which highly correlated to vessel density (CD31 IHC). Westerns blots confirmed the presence of TEM8 in the 6 tumor types but found undetectable TEM8 levels in DLD-1 and MKN-45 cells. This data would indicate that TEM8 is associated with the tumor vasculature rather than the tumor tissue, thus explaining the increased TEM8 expression in DLD-1 tumors compared to DLD-1 cell cultures. (89)Zr-df-L2mAb specifically targeted TEM8 in vitro and in vivo although the in vitro expression was not necessarily predictive of in vivo expression which seemed to be associated with the tumor vasculature. In mouse models, (89)Zr-df-L2mAb tumor uptakes and T:M ratios were sufficient for visualization during PET imaging. These results would suggest that a TEM8 targeted PET imaging agent, such as (89)Zr-df-L2mAb, may have potential clinical, diagnostic, and prognostic applications by providing a quantitative measure of tumor angiogenesis and patient selection for future TEM8 directed therapies.

Short-term outcomes of vaginal mesh placement among female Medicare beneficiaries.

OBJECTIVE: To compare short-term outcomes between prolapse repairs with and without mesh using a national data set. Mesh use in surgical treatment of pelvic organ prolapse has gained wide popularity. However, mesh complications have increased concomitantly with its use. METHODS: Public Use File data were obtained for a 5% random national sample of female Medicare beneficiaries aged 65 years and older. Women who underwent prolapse surgery were identified using Current Procedural Terminology Coding System, Fourth Edition (CPT-4) codes. Because the code for mesh placement was effected in 2005, we separated patients into 3 cohorts as follows: those who underwent prolapse repairs from 1999 to 2000 (presumably without mesh), those who underwent repairs from 2007 to 2008 (presumably without mesh), and those with mesh (based on CPT-4 code 57267) from 2007 to 2008. One-year outcomes were identified using International Classification of Diseases, Ninth Revision diagnosis and procedure codes and CPT-4 procedure codes. RESULTS: A total of 9180 prolapse repairs without mesh were performed from 1999 to 2000, 7729 without mesh from 2007 to 2008, and 1804 prolapse repairs with mesh from 2007 to 2008. Prolapse reoperation within 1 year of surgery was higher in nonmesh vs mesh cohorts (6%-7% vs 4%, P <.02). Mesh removal rates were higher in mesh vs nonmesh group (4% vs 0%-1%, P <.001). Mesh use was associated with more dyspareunia, mesh-related complications, and urinary retention, even when controlling for concomitant sling. CONCLUSION: Mesh to treat pelvic organ prolapse and stress urinary incontinence was associated with a small decrease in early reoperation for prolapse. This decrease came at the expense of increased rates of pelvic pain, retention, mesh-related complications, and mesh removal.

Patients' understanding of pelvic floor disorders: what women want to know.

OBJECTIVE: To assess the effect of initial visit with a specialist on disease understanding in women with pelvic floor disorders. METHODS: Women with referrals or chief complaints suggestive of urinary incontinence or pelvic organ prolapse were recruited from an academic urology clinic. The patients completed a Test of Functional Health Literacy in Adults and scripted interview sessions before and after a physician encounter. Physician's treatment plans were standardized based on diagnosis and were explained using models. Interview transcripts were analyzed using qualitative grounded theory methodology. RESULTS: Twenty women with pelvic floor disorders (urinary incontinence or pelvic organ prolapse) were recruited and enrolled in this pilot study. The mean age was 60.5 years (range, 31-87 years) and most of the women were white, with a college degree or beyond. Test of Functional Health Literacy in Adults scores indicated adequate to high levels of health literacy. Preliminary themes before and after the physician encounter were extracted from interviews, and 2 main concepts emerged. First, after the initial physician's visit, knowledge of their diagnosis and the ability to treat their symptoms relieved the patients' concerns related to misunderstandings of the severity of their disease, Second, the patients tended to focus on treatment and had difficulty grasping certain diagnostic terms. This resulted in good understanding of treatment plans despite an inconsistent understanding of diagnosis. CONCLUSION: Our findings demonstrated a significant effect of the initial physician's visit on the patients' understanding of their pelvic floor disorder. Despite the variation in diagnostic recall after the physician encounter, the patients had a good understanding of treatment plans. This served to increase perceived control and adequately relieve patients' fears.

Review of functional/anatomical imaging in oncology.

Patient management in oncology increasingly relies on imaging for diagnosis, response assessment, and follow-up. The clinical availability of combined functional/anatomical imaging modalities, which integrate the benefits of visualizing tumor biology with those of high-resolution structural imaging, revolutionized clinical management of oncologic patients. Conventional high-resolution anatomical imaging modalities such as computed tomography (CT) and MRI excel at providing details on lesion location, size, morphology, and structural changes to adjacent tissues; however, these modalities provide little insight into tumor physiology. With the increasing focus on molecularly targeted therapies, imaging radiolabeled compounds with PET and single-photon emission tomography (SPECT) is often carried out to provide insight into a tumor's biological functions and its surrounding microenvironment. Despite their high sensitivity and specificity, PET and SPECT alone are substantially limited by low spatial resolution and inability to provide anatomical detail. Integrating SPECT or PET with a modality capable of providing these (i.e. CT or MR) maximizes their separate strengths and provides anatomical localization of physiological processes with detailed visualization of a tumor's structure. The availability of multimodality (hybrid) imaging with PET/CT, SPECT/CT, and PET/MR improves our ability to characterize lesions and affect treatment decisions and patient management. We have just begun to exploit the truly synergistic capabilities of multimodality imaging. Continued advances in the development of instrumentation and imaging agents will improve our ability to noninvasively characterize disease processes. This review will discuss the evolution of hybrid imaging technology and provide examples of its current and potential future clinical uses.

Immuno-PET of the hepatocyte growth factor receptor Met using the 1-armed antibody onartuzumab.

UNLABELLED: The overexpression and overactivation of hepatocyte growth factor receptor (Met) in various cancers has been linked to increased proliferation, progression to metastatic disease, and drug resistance. Developing a PET agent to assess Met expression would aid in the diagnosis and monitoring of responses to Met-targeted therapies. In these studies, onartuzumab, the experimental therapeutic 1-armed monoclonal antibody, was radiolabeled with (76)Br or (89)Zr and evaluated as an imaging agent in Met-expressing cell lines and mouse xenografts. METHODS: (89)Zr-desferrioxamine (df)-onartuzumab was synthesized using a df-conjugate; (76)Br-onartuzumab was labeled directly. Met-binding studies were performed using the human tumor-derived cell lines MKN-45, SNU-16, and U87-MG, which have relatively high, moderate, and low levels of Met, respectively. Biodistribution and small-animal PET studies were performed in MKN-45 and U87-MG xenografts. RESULTS: (76)Br-onartuzumab and (89)Zr-df-onartuzumab exhibited specific, high-affinity Met binding (in the nanomolar range) that was concordant with established Met expression levels. In MKN-45 (gastric carcinoma) xenografts, both tracers cleared slowly from nontarget tissues, with the highest uptake in tumor, blood, kidneys, and lungs. (76)Br-onartuzumab MKN-45 tumor uptake remained relatively constant from 18 h (5 percentage injected dose per gram of tissue [%ID/g]) to 48 h (3 %ID/g) and exhibited tumor-to-muscle ratios ranging from 4:1 to 6:1. In contrast, (89)Zr-df-onartuzumab MKN-45 tumor uptake continued to accumulate from 18 h (10 %ID/g) to 120 h (23 %ID/g), attaining tumor-to-muscle ratios ranging from 20:1 to 27:1. MKN-45 tumors were easily visualized in imaging studies with both tracers at 18 h, but after 48 h (89)Zr-df-onartuzumab image quality improved, with at least 2-fold-greater tumor uptake than nontarget tissues. MKN-45 tumor uptake for both tracers correlated significantly with tumor mass and Met expression and was not affected by the presence of plasma shed Met. CONCLUSION: (89)Zr-df-onartuzumab and (76)Br-onartuzumab specifically targeted Met in vitro and in vivo; (89)Zr-df-onartuzumab achieved higher tumor uptake and tumor-to-muscle ratios than (76)Br-onartuzumab at later times, suggesting that (89)Zr-df-onartuzumab would be better suited to image Met for diagnostic and prognostic purposes.

Aging attenuates the pituitary response to gonadotropin-releasing hormone.

CONTEXT: Complex changes in GnRH secretion occur with aging in women, but little is known about the effect of aging on the pituitary per se. OBJECTIVE: The aim of the study was to determine whether pituitary responsiveness to GnRH is attenuated with aging. DESIGN AND SETTING: A GnRH antagonist and graded doses of GnRH were used to isolate pituitary responsiveness in Clinical Research Center studies at an academic medical center. SUBJECTS: Subjects were healthy postmenopausal women (PMW) aged 48-57 yr (n = 10) or 70-77 yr (n= 9). INTERVENTIONS: A suppressive dose of the NAL-GLU GnRH antagonist (150 microg/kg sc) was administered and was followed by GnRH doses of 25, 75, 250, or 750 ng/kg iv every 4 h. RESULTS: The LH response to GnRH was attenuated with aging (P = 0.05) with an interaction between age and dose (P = 0.01) such that the LH amplitude was less in older PMW at the higher doses (250 ng/kg, 50 +/- 9 vs. 29 +/- 4.9 IU/liter, for young and old PMW, respectively, P = 0.02; and 750 ng/kg, 97.7 +/- 11 vs. 70.2 +/- 9.3 IU/liter, P = 0.002), but not the lower doses of GnRH. The FSH response to GnRH was also attenuated with aging in PMW (P = 0.005). CONCLUSIONS: In studies that isolated the pituitary from endogenous GnRH stimulation, aging attenuated the LH and FSH responses to exogenous GnRH in PMW. These studies indicate that the pituitary plays a role in the decline in gonadotropin levels with aging, further supporting the potential contribution of age-associated changes in both hypothalamic and pituitary function to reproductive senescence.