Re-evaluating the need for chronic toxicity studies with therapeutic monoclonal antibodies, using a weight of evidence approach

To support registration of monoclonal antibodies (mAbs) for chronic indications, 6-month toxicity studies have historically been conducted. Experience with mAb development has shown a relatively benign and well-understood safety profile for this class, with most toxicity findings anticipated based on pharmacology. We evaluated whether a 6-month toxicity study is necessary to assess the long-term safety of mAbs. Data on First-in-Human (FIH)-enabling and chronic toxicity studies were shared for 142 mAbs submitted by 11 companies. Opportunities to further optimize study designs to reduce animal usage were identified. For 71% of mAbs, no toxicities or no new toxicities were noted in chronic studies compared to FIH-enabling study findings. New toxicities of potential concern for human safety or that changed trial design were identified in 13.5% of cases, with 7% being considered critical and 2% leading to program termination. An iterative, weight-of-evidence model which considers factors that influence the overall risk for a mAb to cause toxicity was developed. This model enables an evidence-based justification, suggesting when 3-month toxicity studies are likely sufficient to support late-stage clinical development and registration for some mAbs.

The use of recovery animals in nonclinical safety assessment studies with monoclonal antibodies: further 3Rs opportunities remain

Assessment of reversibility from nonclinical toxicity findings in animals with potential adverse clinical impact is required during pharmaceutical development, but there is flexibility around how and when this is performed and if recovery animals are necessary. For monoclonal antibodies (mAbs) and in accordance with ICH S6(R1) if inclusion of recovery animals is warranted, this need only occur in one study. Data on study designs for first-in-human (FIH)-enabling and later-development toxicity studies were shared from a recent collaboration between the NC3Rs, EPAA, Netherlands Medicines Evaluation Board (MEB) and 14 pharmaceutical companies. This enabled a review of practices on recovery animal use during mAb development and identification of opportunities to reduce research animal use. Recovery animals were included in 68% of FIH-enabling and 69% of later-development studies, often in multiple studies in the same program. Recovery groups were commonly in control plus one test article-dosed group or in all dose groups (45% of studies, each design). Based on the shared data review and conclusions, limiting inclusion of recovery to a single nonclinical toxicology study and species, study design optimisation and use of existing knowledge instead of additional recovery groups provide opportunities to further reduce animal use within mAb development programs.

Nonclinical Development of Biologics: Integrating Safety, Pharmacokinetics, and Pharmacodynamics to Create Smarter and More Flexible Nonclinical Safety Programs Optimizing Animal Use

Safety assessment of biological drugs has its challenges due to the multiple new different modalities, for example, antibody-drug conjugates, bispecifics, nanobodies, fusion proteins and advanced therapy medicinal products (ATMPs), their different pharmacokinetic and pharmacodynamic properties, and their ability to trigger immunogenicity and toxicity. In the public and in the pharmaceutical industry, there is a strong and general desire to reduce the number of animals used in research and development of drugs and in particular reducing the use of nonhuman primates. Important discussions and activities are ongoing investigating the smarter designs of early research and dose range finding studies, reuse of animals, and replacing animal experiments with in vitro studies. Other important challenges include absence of a relevant species and design of studies and developing genetically modified animals for special investigative toxicology studies. Then, the learnings and challenges from the development of the first ATMPs are available providing valuable insights in the development path for these new potentially transformative treatments. Finally, development of strategies for assessment of immunogenicity and prediction of translation of immunogenicity and associated findings to the clinic. On this, the eighth meeting for the European BioSafe members, these challenges served as the basis for the presentations and discussions during the meeting. This article serves as the workshop report reviewing the presentations and discussions at the meeting.

Challenges of non-clinical safety testing for biologics: A Report of the 9th BioSafe European Annual General Membership Meeting

New challenges and other topics in non-clinical safety testing of biotherapeutics were presented and discussed at the nineth European BioSafe Annual General Membership meeting in November 2019. The session topics were selected by European BioSafe organization committee members based on recent company achievements, agency interactions and new data obtained in the non-clinical safety testing of biotherapeutics, for which data sharing would be of interest and considered as valuable information. The presented session topics ranged from strategies of in vitro testing, immunogenicity prediction, bioimaging, and developmental and reproductive toxicology (DART) assessments to first-in-human (FIH) dose prediction and bioanalytical challenges, reflecting the entire space of different areas of expertise and different molecular modalities. During the 9th meeting of the European BioSafe members, the following topics were presented and discussed in 6 main sessions (with 3 or 4 presentations per session) and in three small group breakout sessions: 1) DART assessment with biotherapeutics: what did we learn and where to go?; 2) Non-animal testing strategies; 3) Seeing is believing: new frontiers in imaging; 4) Predicting immunogenicity during early drug development: hope or despair?; 5) Challenges in FIH dose projections; and 6) Non-canonical biologics formats: challenges in bioanalytics, PKPD and biotransformation for complex biologics formats. Small group breakout sessions were organized for team discussion about 3 specific topics: 1) Testing of cellular immune function in vitro and in vivo; 2) MABEL approach (toxicology and pharmacokinetic perspective); and 3) mRNA treatments. This workshop report presents the sessions and discussions at the meeting.

Baseline staging imaging for distant metastasis in women with stages I, II, and III breast cancer

Background

In Ontario, there is no clearly defined standard of care for staging for distant metastasis in women with newly diagnosed and biopsy-confirmed breast cancer whose clinical presentation is suggestive of early-stage disease. This guideline addresses baseline imaging investigations for women with newly diagnosed primary breast cancer who are otherwise asymptomatic for distant metastasis.

Methods

The medline and embase databases were systematically searched for evidence from January 2000 to April 2019, and the best available evidence was used to draft recommendations relevant to the use of baseline imaging investigation in women with newly diagnosed primary breast cancer who are otherwise asymptomatic. Final approval of this practice guideline was obtained from both the Staging in Early Stage Breast Cancer Advisory Committee and the Report Approval Panel of the Program in Evidence-Based Care.

Recommendations

These recommendations apply to all women with newly diagnosed primary breast cancer (originating in the breast) who have no symptoms of distant metastasis Staging tests using conventional anatomic imaging [chest radiography, liver ultrasonography, chest-abdomen-pelvis computed tomography (ct)] or metabolic imaging modalities [integrated positron-emission tomography (pet)/ct, integrated pet/magnetic resonance imaging (mri), bone scintigraphy] should not be routinely ordered for women newly diagnosed with clinical stage i or stage ii breast cancer who have no symptoms of distant metastasis, regardless of biomarker status. In women newly diagnosed with stage iii breast cancer, baseline staging tests using either anatomic imaging (chest radiography, liver ultrasonography, chest-abdomen-pelvis ct) or metabolic imaging modalities (pet/ct, pet/mri, bone scintigraphy) should be considered regardless of whether the patient is symptomatic for distant metastasis and regardless of biomarker profile.

"Simulect" as a model compound for assessing placental transfer of monoclonal antibodies in minipigs

The aim of this study was to directly test and measure in vivo, if placental transfer of monoclonal antibodies takes place in pregnant Göttingen Minipigs to assess their suitability for reproductive assessment of therapeutic monoclonal antibodies. Simulect®, an approved anti CD25 (anti IL-2 receptor alpha) chimeric monoclonal IgG1 antibody, was used as a model monoclonal antibody. Maternal systemic exposure and potential placental transfer of Simulect® to fetuses were investigated following 4 weekly bolus intravenous administration of 5.0 mg/kg from gestation day (GD) 79 or 80 (e.g GD 79, 86, 93 and 100) and with terminal Caesarean section on GD 108 or GD 109 respectively. Results clearly showed exposure in maternal animals, detectable compound in the amniotic fluid from one out of 9 maternal animals, but no exposure in fetuses confirming absence of placental transfer of the selected model antibody Simulect® in minipigs. The absence of Simulect® in the fetuses further supports that the presence of Simulect® in the amniotic fluid in one maternal animal was likely due to contamination with maternal blood during sampling. The demonstrated absence of fetal exposure clearly indicates that, the minipig is not a suitable species for conduct of reproductive toxicity studies with monoclonal antibodies.

Biotherapeutics in non-clinical development: Strengthening the interface between safety, pharmacokinetics-pharmacodynamics and manufacturing

Biological drugs comprise a wide field of different modalities with respect to structure, pharmacokinetics and pharmacological function. Considerable non-clinical experience in the development of proteins (e.g. insulin) and antibodies has been accumulated over the past thirty years. In order to improve the efficacy and the safety of these biotherapeutics, Fc modifications (e.g. Fc silent antibody versions), combinations (antibody-drug conjugates, protein-nanoparticle combinations), and new constructs (darpins, fynomers) have been introduced. In the last decade, advanced therapy medicinal products (ATMPs) in research and development have become a considerable and strongly growing part of the biotherapeutic portfolio. ATMPs consisting of gene and cell therapy modalities or even combinations of them, further expand the level of complexity, which already exists in non-clinical development strategies for biological drugs and has thereby led to a further diversification of expertise in safety and PKPD assessment of biological drugs. It is the fundamental rationale of the BioSafe meetings, held yearly in the EU and in the US, to convene experts on a regular basis and foster knowledge exchange and mutual understanding in this fast growing area. In order to reflect at least partially the variety of the biotherapeutics field, the 2016 EU BioSafe meeting addressed the following topics in six sessions: (i) In vitro Meets in vivo to Leverage Biologics Development (ii) New developments and regulatory considerations in the cell and gene therapy field (iii) CMC Challenges with Biologics development (iv) Minipigs in non-clinical safety assessment (v) Opportunities of PKPD Assessment in Less Common Administration Routes In the breakout sessions the following questions were discussed: (i) Cynomolgus monkey as a reprotoxicology Species: Impact of Immunomodulators on Early Pregnancy Maintenance (ii) Safety Risk of Inflammation and Autoimmunity Induced by Immunomodulators (iii) Experience with non-GMP Material in Pivotal Non-clinical Safety Studies to Support First in Man (FiM) Trials (iv) Safety Assessment of Combination Products for Non-oncology.

Lessons learned implementing a province-wide smoking cessation initiative in Ontario's cancer centres

PURPOSE

A large body of evidence clearly shows that cancer patients experience significant health benefits with smoking cessation. Cancer Care Ontario, the provincial agency responsible for the quality of cancer services in Ontario, has undertaken a province-wide smoking cessation initiative. The strategies used, the results achieved, and the lessons learned are the subject of the present article.

METHODS

Evidence related to the health benefits of smoking cessation in cancer patients was reviewed. A steering committee developed a vision statement for the initiative, created a framework for implementation, and made recommendations for the key elements of the initiative and for smoking cessation best practices.

RESULTS

New ambulatory cancer patients are being screened for their smoking status in each of Ontario's 14 regional cancer centres. Current or recent smokers are advised of the benefits of cessation and are directed to smoking cessation resources as appropriate. Performance metrics are captured and used to drive improvement through quarterly performance reviews and provincial rankings of the regional cancer centres.

CONCLUSIONS

Regional smoking cessation champions, commitment from Cancer Care Ontario senior leadership, a provincial secretariat, and guidance from smoking cessation experts have been important enablers of early success. Data capture has been difficult because of the variety of information systems in use and non-standardized administrative and clinical processes. Numerous challenges remain, including increasing physician engagement; obtaining funding for key program elements, including in-house resources to support smoking cessation; and overcoming financial barriers to access nicotine replacement therapy. Future efforts will focus on standardizing processes to the extent possible, while tailoring the approaches to the populations served and the resources available within the individual regional cancer programs.

FcRn Expression on Placenta and Fetal Jejunum during Early, Mid-, and Late Gestation in Minipigs

Developmental toxicity testing of therapeutic antibodies is most often conducted in nonhuman primates owing to lack of cross-reactivity in other species. Minipigs may show cross-reactivity for some humanized antibodies but have not been used for developmental toxicity testing due to an assumed lack of embryo-fetal exposure. Unlike in humans, maternal IgGs do not cross the porcine placenta to reach the fetus. Some humanized IgGs, however, have a higher affinity for the neonatal Fc receptor (FcRn) and are more likely than endogenous antibodies to cross the placenta of animals. The major site of prenatal IgG transfer is the placenta, though FcRn in fetal intestine could also uptake maternal IgGs from swallowed amniotic fluid. Using immunohistochemistry andin situhybridization in this experiment, FcRn was found in minipig placenta and fetal intestine during early, mid-, and late gestation. To date, however, fetal exposure to maternally administered IgGs has never been demonstrated in the minipig.

Safety and immunotoxicity assessment of immunomodulatory monoclonal antibodies

Most therapeutic monoclonal antibodies (mAbs) licensed for human use or in clinical development are indicated for treatment of patients with cancer and inflammatory/autoimmune disease and as such, are designed to directly interact with the immune system. A major hurdle for the development and early clinical investigation of many of these immunomodulatory mAbs is their inherent risk for adverse immune-mediated drug reactions in humans such as infusion reactions, cytokine storms, immunosuppression and autoimmunity. A thorough understanding of the immunopharmacology of a mAb in humans and animals is required to both anticipate the clinical risk of adverse immunotoxicological events and to select a safe starting dose for first-in-human (FIH) clinical studies. This review summarizes the most common adverse immunotoxicological events occurring in humans with immunomodulatory mAbs and outlines non-clinical strategies to define their immunopharmacology and assess their immunotoxic potential, as well as reduce the risk of immunotoxicity through rational mAb design. Tests to assess the relative risk of mAb candidates for cytokine release syndrome, innate immune system (dendritic cell) activation and immunogenicity in humans are also described. The importance of selecting a relevant and sensitive toxicity species for human safety assessment in which the immunopharmacology of the mAb is similar to that expected in humans is highlighted, as is the importance of understanding the limitations of the species selected for human safety assessment and supplementation of in vivo safety assessment with appropriate in vitro human assays. A tiered approach to assess effects on immune status, immune function and risk of infection and cancer, governed by the mechanism of action and structural features of the mAb, is described. Finally, the use of immunopharmacology and immunotoxicity data in determining a minimum anticipated biologic effect Level (MABEL) and in the selection of safe human starting dose is discussed.

Sym004: a novel synergistic anti-epidermal growth factor receptor antibody mixture with superior anticancer efficacy

Epidermal growth factor receptor (EGFR) is a validated therapeutic target in cancer and EGFR antagonists with greater effectiveness than existing clinical agents remain of interest. Here, we report a novel approach based on Sym004, a mixture of two anti-EGFR monoclonal antibodies directed against distinct nonoverlapping epitopes in EGFR extracellular domain III. Like anti-EGFR monoclonal antibodies in current clinical use, Sym004 inhibits cancer cell growth and survival by blocking ligand-binding receptor activation and phosphorylation and downstream receptor signaling. However, unlike the other antibodies, Sym004 induces rapid and efficient removal of the receptor from the cancer cell surface by triggering EGFR internalization and degradation. Compared with reference anti-EGFR monoclonal antibodies, Sym004 exhibited more pronounced growth inhibition in vitro and superior efficacy in vivo. Together, these findings illustrate a strategy to target EGFR more effectively than existing clinical antibodies.

Influence of somatostatin to biochemical parameters in patients with primary hyperparathyroidism

Somatostatin (SRIF) is effective in the nonoperative management of a variety endocrine tumors. A potential role of SRIF for treatment of patients with primary hyperparathyroidism (pHPT) has been suggested. In a controlled, prospective, triple-blinded, randomized clinical trial, the somatostatin analogue octreotide (SMS 201-995, Sandostatin) was evaluated in 40 patients with well documented pHPT. Amongst other biochemical parameters, serum calcium and-phosphate and levels of parathyroid hormone, calcitonin, and osteocalcin as well as octreotide were assessed before and for 4 hours after a single iv. application of 200 micrograms ocreotide or placebo. SRIF-receptor autoradiography was performed in parathyroid tissue samples. Baseline values revealed a constellation of biochemical parameters typically found in pHPT. Following 200 micrograms octreotide, no significant changes in any of the biochemical parameters investigated for were observed. Multivariate analysis was performed to identify patient subpopulations in which any given combination of laboratory parameters changed in response to either drug or placebo. However, no 'responders' to octreotide were identified. 45% of patients receiving octreotide, reported side effects. Parathyroid tissue samples were negative for SRIF-receptor expression. It is concluded that a single dose iv. application of octreotide does not result in appreciable changes of biochemical parameters relevant in pHPT and carries a high rate of side effects. Furthermore, absence of SRIF-receptors in parathyroid tissue from patients with pHPT, together with lack of octreotide effects, suggests that somatostatin-analogues may not be effective in the non-operative therapy of pHPT.

The agnogene of the human polyomavirus BK is expressed

Primate polyomavirus genomes all contain an open reading frame at the 5' end of the late coding region called the agnogene. A simian virus 40 agnoprotein with unknown functions has previously been demonstrated. We now show that a BK virus agnoprotein appears in the perinuclear area and cytoplasm late in the infectious cycle. It is phosphorylated in vivo and coimmunoprecipitates with a subset of host cell proteins.

[Development of adenocarcinoma in a retrorectal pre-sacrococcygeal hamartoma]

Among the different pathologic structures of the presacrococcygeal space retrorectal cystic hamartomas are uncommon lesions. These cysts are most likely derived from remnants of the embryonic tailgut although an association to teratomas may exist. We describe the clinicopathologic features of a retrorectal cystic hematoma with malignant transformation in a 60 year old female patient. The literature is reviewed and etiology, diagnosis and operative management are discussed.

Dichotomy of the T cell response to Leishmania antigens in patients suffering from cutaneous leishmaniasis; absence or scarcity of Th1 activity is associated with severe infections

The T cell response was studied in 25 patients suffering from cutaneous leishmaniasis caused by Leishmania major with severe (n = 10) and mild (n = 15) disease manifestations. Peripheral blood mononuclear cells (PBMC) from the patients were activated by sonicates of Leishmania promastigotes (LMP) and amastigotes (LDA), and the surface protease gp63. The proliferative responses to Leishmania antigens were lower in patients with severe disease than in patients with mild disease (P = 0.01-0.05), and such a difference was not observed in the response to purified protein derivative of tuberculin (PPD) or tetanus toxoid (TT). LMP-induced interferon-gamma (IFN-gamma) production was lower in patients with severe than in patients with mild disease (P < 0.05). When the IL-4 and IFN-gamma responses of each patient were considered, two response patterns were observed in the cultures activated by the Leishmania sonicates. One response pattern was characterized by high production of IFN-gamma without production of IL-4 (a Th1-like pattern), the other was characterized by low IFN-gamma levels which in most cases were associated with IL-4 production (not a Th1-like pattern). These patterns could not be distinguished when the cells from the same donors were stimulated by TT and PPD. The percentages of patients with a Th1-like response pattern after stimulation by LMP in patients with severe and mild disease manifestations were 30% and 80%, respectively. This difference was statistically significant (P = 0.034).

Trichoblastic fibroma (fibromatoid trichoepithelioma)

Six examples of so-called trichoblastic fibroma occurred in five females and one male. The age of the patients ranged from 46 to 70 years (mean: 61 years). Three tumours were on the back, one each on the left gluteus, right skull and left thigh; they were present one to 20 years and varied in size from 1.8 to 6 cm. The tumour nodules were easily shelled out at operation, and the macroscopic aspect was that of fibroma. Although there seems to be a close relationship to trichoepitheliomas, this tumour deserves a separation from classical conventional trichoepitheliomas and differs from these by size, consistency, involvement of deeper tissues, nodular character, unusual location, age of patients and additional histopathologic findings. In our opinion, these rare tumours may also be classified as fibromatoid trichoepitheliomas.

[Vascular eccrine giant spiradenoma--a case report with histology and immunohistology of a rare variant of benign sweat gland tumors]

Giant vascular eccrine spiradenoma (GVES) is a rare variant of benign tumors of the sweat glands, which differs from common eccrine spiradenoma in both its size and vascularity. Clinically as well as macroscopically, this intradermal or subcutaneous encapsulated tumor might be mistaken for an angiomatous lesion or thrombosis. Histological examination reveals clearly delimited "cords" showing two types of cells, prominent blood-filled cavities and extensive hemorrhages. According to immunohistochemical findings, the epithelial cells contain cytokeratin, protein S-100 and carcino-embryonal antigen (CEA). Like the endothelial cells of vessels, some of the luminal epithelial cells also bind Ulex europaeus lectin; however, they do not show factor VIII-associated antigen.

[Arterial fibromuscular dysplasia as an unexpected cause of death in adults]

In a 38-year-old woman, arterial hypertension was diagnosed a few weeks before her death. She died unexpectedly before a diagnostic clarification of the cause was possible. Autopsy revealed an arterial fibromuscular dysplasia with manifestation in both common iliac arteries, both renal arteries, the celiac trunk and the splenic artery. Both renal arteries displayed stenotic dissecant aneurysms which were the cause of the arterial hypertension. As a rare and lethal complication of fibromuscular dysplasia, a ruptured saccular aneurysm was found in the splenic artery. Histologically, the vascular alterations were a combination of medical fibromuscular dysplasia (type II) and periarterial or adventitial fibroplasia (type III). On the basis of the immunohistochemical detection of abundant lysozyme-positive cells, the periarterial fibroplasia appears to be a secondary chronic granulating and cicatricial reaction and not a separate form of fibromuscular dysplasia.

Embryonal brain neoplasms in the neonatal period and early infancy

We report on two cases of congenital primitive neuroectodermal tumors located in the posterior cranial fossa. They were symptomatic at birth with occlusive internal hydrocephalus. Clinical investigations had failed to diagnose brain tumors and had led to the suggestion of maldevelopment syndromes. In one of these children a malignant rhabdoid tumor of the kidney was operated at the age of 4 1/2 months. Autopsy revealed medulloblastoma combined with a malignant rhabdoid tumor of the kidney in one case and ependymoblastoma in the other.

Comparison of bronchoalveolar lavage helper/suppressor T-cell ratios in sarcoidosis versus other interstitial lung diseases

In order to compare the frequency of elevated lymphocyte proportions and elevated Leu3/Leu2 (helper/inducer to suppressor/cytotoxic) ratios in sarcoidosis with those in clinically similar interstitial lung diseases (ILDs), bronchoalveolar lavage (BAL) lymphocyte proportions and Leu3/Leu2 ratios were determined for 20 patients with sarcoidosis and 30 patients with other (non-sarcoidosis) ILDs [cryptogenic fibrosing alveolitis (seven), lung connective tissue disease (seven), extrinsic allergic alveolitis (four), lymphoproliferative disease (two), and asbestosis (ten)], as well as in eight control subjects. BAL lymphocyte proportions were elevated above control values in 19 (95%) patients with pulmonary sarcoidosis (mean value 36 +/- 3%) but also in 12 (39%) patients with non-sarcoidosis ILDs (mean value 17 +/- 4%). Leu3/Leu2 ratios were over 2.5 in 15 (75%) of the sarcoidosis patients (mean ratio 4.4 +/- 1). In all control subjects, however, and in all but one of the non-sarcoidosis groups, Leu3/Leu2 ratios were below 2.5 (p less than 0.001 for each compared to sarcoidosis patients). Helper/suppressor ratios over 2.5 are found in the majority of our sarcoidosis patients and, unlike raised lymphocyte proportions alone, are not commonly seen in other ILDs, suggesting that evaluation of BAL helper/suppressor cell ratios may be of value in the investigation of patients with ILD.

[Bacterial infection of an Ionescu-Shiley bioprosthesis. Morphologic studies]

Bacterial inflammation associated with artificial cardiac valves is a rare complication after valve replacement but is burdened with a high lethality. Whereas in the case of mechanical valves the infection involves the body's own tissues, bacterial colonisation of valves made of prepared biological material can also occur. The morphology of the bacterial inflammation was examined in a case of early postoperative endocarditis. Although the bacterial infection in the paravalvular tissues resulted in a purulent inflammation, the Ionescu-Shiley-bovine bioprosthesis remained free of inflammatory cells despite extensive vegetative bacterial growth.

[Ultrastructural studies of vacuole formation in arterial chorionic vessels of the mature human placenta]

The so called endothelial vacuoles of the human fetal stem arteries are formed by contraction of the tunica muscularis media. The cytoplasm of the smooth muscle cells prolapses through gaps of the basal membrane, found in areas of myoendothelial junctions, into the intima. Perfusion with fixative immediately after delivery prevents the formation of the vacuoles.

[Rare complication of fibromuscular dysplasia of the internal carotid artery (author's transl)]

Following resection of an angiographically demonstrated fibromuscular stenosis of the renal artery--the cause of long-standing arteria hypertension--there occurred a thrombotic occlusion of the fibromuscular-dysplastic internal carotid artery from which the 34-year-old woman died. The treatment of choice of fibromuscular stenosis of the renal artery with renovascular hypertension is resection of the stenosis with revascularisation or nephrectomy. Since fibromuscular dysplasia is a generalised vascular disease in which all arteries of the muscular type may participate, angiography of the extra-renal, in particular cervical, arteries should be performed preoperatively in addition to the renal artery angiograms.