Normative values of the aortic valve area and Doppler measurements using two-dimensional transthoracic echocardiography: results from the Multicentre World Alliance of Societies of Echocardiography Study

AIMS

Aortic valve area (AVA) used for echocardiographic assessment of aortic stenosis (AS) has been traditionally interpreted independently of sex, age and race. As differences in normal values might impact clinical decision-making, we aimed to establish sex-, age- and race-specific normative values for AVA and Doppler parameters using data from the World Alliance Societies of Echocardiography (WASE) Study.

METHODS AND RESULTS

Two-dimensional transthoracic echocardiographic studies were obtained from 1903 healthy adult subjects (48% women). Measurements of the left ventricular outflow tract (LVOT) diameter and Doppler parameters, including AV and LVOT velocity time integrals (VTIs), AV mean pressure gradient, peak velocity, were obtained according to ASE/EACVI guidelines. AVA was calculated using the continuity equation. Compared with men, women had smaller LVOT diameters and AVA values, and higher AV peak velocities and mean gradients (all P < 0.05). LVOT and AV VTI were significantly higher in women (P < 0.05), and both parameters increased with age in both sexes. AVA differences persisted after indexing to body surface area. According to the current diagnostic criteria, 13.5% of women would have been considered to have mild AS and 1.4% moderate AS. LVOT diameter and AVA were lower in older subjects, both men and women, and were lower in Asians, compared with whites and blacks.

CONCLUSION

WASE data provide clinically relevant information about significant differences in normal AVA and Doppler parameters according to sex, age, and race. The implementation of this information into clinical practice should involve development of specific normative values for each ethnic group using standardized methodology.

Age-, Sex-, and Race-Based Normal Values for Left Ventricular Circumferential Strain from the World Alliance Societies of Echocardiography Study

BACKGROUND

Left ventricular (LV) circumferential strain has received less attention than longitudinal deformation, which has recently become part of routine clinical practice. Among other reasons, this is because of the lack of established normal values. Accordingly, the aim of this study was to establish normative values for LV circumferential strain and determine sex-, age-, and race-related differences in a large cohort of healthy adults.

METHODS

Complete two-dimensional transthoracic echocardiograms were obtained in 1,572 healthy subjects (51% men), enrolled in the World Alliance Societies of Echocardiography Normal Values Study. Subjects were divided into three age groups (<35, 35-55, and >55 years) and stratified by sex and by race. Vendor-independent semiautomated speckle-tracking software was used to determine LV regional circumferential strain and global circumferential strain (GCS) values. Limits of normal for each measurement were defined as 95% of the corresponding sex and age group falling between the 2.5th and 97.5th percentiles. Intergroup differences were analyzed using unpaired t tests.

RESULTS

Circumferential strain showed a gradient, with lower magnitude at the mitral valve level, increasing progressively toward the apex. Compared with men, women had statistically higher magnitudes of regional and global strain. Older age was associated with a stepwise increase in GCS despite an unaffected ejection fraction, a decrease in LV volume, and relatively stable global longitudinal strain in men, with a small gradual decrease in women. Asian subjects demonstrated significantly higher GCS magnitudes than whites of both sexes and blacks among women only. In contrast, no significant differences in GCS were found between white and black subjects of either sex. Importantly, despite statistical significance of these differences across sex, age, and race, circumferential strain values were similar in all groups, with variations of the order of magnitude of 1% to 2%. Notably, no differences in GCS were found among brands of imaging equipment.

CONCLUSION

This study established normal values of LV regional circumferential strain and GCS and identified sex-, age-, and race-related differences when present.

Unmet Need for Further LDL-C Lowering in India despite Statin Therapy: Lipid Association of India Recommendations for the Use of Bempedoic Acid

Lipid-lowering therapy plays a crucial role in reducing adverse cardiovascular (CV) events in patients with established atherosclerotic cardiovascular disease (ASCVD) and familial hypercholesterolemia. Lifestyle interventions along with high-intensity statin therapy are the first-line management strategy followed by ezetimibe. Only about 20-30% of patients who are on maximally tolerated statins reach recommended low-density lipoprotein cholesterol (LDL-C) goals. Several factors contribute to the problem, including adherence issues, prescription of less than high-intensity statin therapy, and de-escalation of statin dosages, but in patients with very high baseline LDL-C levels, including those with familial hypercholesterolemia and those who are intolerant to statins, it is critical to expand our arsenal of LDL-C-lowering medications. Moreover, in the extreme risk group of patients with an LDL-C goal of ≤30 mg/dL according to the Lipid Association of India (LAI) risk stratification algorithm, there is a significant residual risk requiring the addition of non-statin drugs to achieve LAI recommended targets. This makes bempedoic acid a welcome addition to the existing non-statin therapies such as ezetimibe, bile acid sequestrants, and PCSK9 inhibitors. A low frequency of muscle-related side effects, minimal drug interactions, a significant reduction in high-sensitivity C-reactive protein (hsCRP), and a lower incidence of new-onset or worsening diabetes make it a useful adjunct for LDL-C lowering. However, the CV outcomes trial results are still pending. In this LAI consensus document, we discuss the pharmacology, indications, contraindications, advantages, and evidence-based recommendations for the use of bempedoic acid in clinical practice.

Three-Dimensional Transthoracic Static and Dynamic Normative Values of the Mitral Valve Apparatus: Results from the Multicenter World Alliance Societies of Echocardiography Study

BACKGROUND

Recent advances in mitral valve (MV) percutaneous interventions have escalated the need for a more quantitative and comprehensive assessment of the MV, which can be best achieved using three-dimensional echocardiography. Understanding normal valve size, structure, and function is essential for differentiation of healthy from disease states. The aims of this study were to establish normative values for MV apparatus size and morphology and to determine how they vary across age, sex, and race groups using data from the World Alliance Societies of Echocardiography Normal Values Study.

METHODS

Three-dimensional volumetric data sets obtained on transthoracic echocardiography in 748 normal subjects (51% men) were analyzed using commercial MV analysis software (TomTec Imaging Systems) to determine annular and leaflet dimensions and areas. The subjects were divided into groups by sex (378 men and 370 women) and age (18 to 40 years [n = 266], 41 to 65 years [n = 249], and >65 years [n = 233]) to identify sex- and age-related differences. In addition, differences among black, white, and Asian populations were studied. Inter- and intraobserver variability was assessed in a subset of 30 subjects and expressed as mean absolute difference between pairs of repeated measurements.

RESULTS

Compared with women, men had larger annular size measurements, larger tenting size parameters, and larger leaflet length and area. Compared with the black and white populations, the Asian population showed significantly smaller mitral annular size. Although many of the age, sex, and race differences in MV parameters were statistically significant, they were comparable with or smaller than the corresponding measurement variability. Indexing to body surface area and height did not eliminate these differences consistently, suggesting that parameters may need to be indexed according to their dimensionality.

CONCLUSIONS

This analysis of the World Alliance Societies of Echocardiography data provides normative values of mitral apparatus size and morphology. Although sex- and age-related differences were noted, they need to be interpreted with caution in view of the associated measurement variability.

Risk Factors Analysis and Management of Cardiometabolic-Based Chronic Disease in Low- and Middle-Income Countries

The epidemic of obesity or adiposity-based chronic diseases presents a significant challenge with the rising prevalence of morbidities and mortality due to atherosclerotic cardiovascular diseases (ASCVD), especially in low- and middle-income countries (LMIC). The underlying pathophysiology of metabolic inflexibility is a common thread linking insulin resistance to cardiometabolic-based chronic disease (CMBCD), including dysglycemia, hypertension, and dyslipidemia progressing to downstream ASCVD events. The complex CMBCD paradigm in the LMIC population within the socio-economic and cultural context highlights considerable heterogeneity of disease predisposition, clinical patterns, and socio-medical needs. This review intends to summarize the current knowledge of CMBCD. We describe recently established or emerging trends for managing risk factors, assessment tools for evaluating ASCVD risk, and various pharmacological and non-pharmacological measures particularly relevant for LMICs. A CMBCD model positions insulin resistance and β-cell dysfunction at the summit of the disease spectrum may improve outcomes at a lower cost in LMICs. Despite identifying multiple pathophysiologic disturbances constituting CMBCD, a large percentage of the patient at risk for ASCVD remains undefined. Targeting dysglycemia, dyslipidemia, and hypertension using antihypertensive, statins, anti-glycemic, and antiplatelet agents has reduced the incidence of ASCVD. Thus, primordial prevention targeting pathophysiological changes that cause abnormalities in adiposity and primary prevention by detecting and managing risk factors remains the foundation for CMBCD management. Therefore, targeting pathways that address mitochondrial dysfunction would exert a beneficial effect on metabolic inflexibility that may potentially correct insulin resistance, β cell dysfunction and, consequently, would be therapeutically effective across the entire continuum of CMBCD.

POS0022 PHARMACOVIGILANCE PREGNANCY DATA IN A LARGE POPULATION OF PATIENTS WITH CHRONIC INFLAMMATORY DISEASE EXPOSED TO CERTOLIZUMAB PEGOL: PREGNANCY OUTCOMES AND CONFOUNDERS

Background:

Chronic inflammatory diseases (CID) in women of reproductive age are increasingly being treated with tumour necrosis factor inhibitors (TNFi), in line with recent guidelines.1 However, data on TNFi-exposed pregnancy outcomes are still limited. Certolizumab pegol (CZP), a PEGylated, Fc-free TNFi, has no/minimal placental transfer from mother to infant during the third trimester.2

Objectives:

To assess pregnancy outcomes from the UCB Pharmacovigilance safety database from over 1,300 prospectively reported pregnancies with maternal CZP exposure.

Methods:

Details of CZP-exposed pregnancies from the UCB Pharmacovigilance safety database were reviewed up to November 1, 2020. Analysis was limited to prospectively reported cases with known pregnancy outcomes to avoid potential reporting bias. Confounders (specific CID, non-biologic medications and maternal infection) were evaluated using a multivariate stepwise regression model; results from the confounders analysis are reported as odds ratios (OR) with 95% confidence intervals (CI). Patients with missing information about presence or absence of confounders were excluded from the model.

Results:

1,392 prospective pregnancies (1,425 fetuses) with maternal CZP exposure and known outcomes were reported (Figure 1). Mean (SD) maternal age was 31.9 (5.1) years. Of these, 1,021/1,392 (73.3%) pregnancies had at least first-trimester CZP exposure and 547/1,392 (39.3%) were exposed during all trimesters. Overall, there were 1,259/1,425 (88.4%) live births, 150/1,425 (10.5%) abortions (miscarriages and terminations), 11/1,425 (0.8%) stillbirths, and 5/1,425 (0.4%) ectopic pregnancies. Congenital malformations were reported in 35/1,425 fetuses (2.5%) and in 30/1,259 live-born infants (2.4%); 26 (2.1%) congenital malformations were major according to the Metropolitan Atlanta Congenital Defects Program criteria. There was no pattern of specific congenital malformations. Preterm births occurred in 124/1,259 (9.8%) live births, and 101/1,259 (8.0%) of infants had low birth weight (<2.5 kg). In the confounders analysis, reported corticosteroid use was independently associated with increased odds of preterm birth (OR [95% CI]: 2.1 [1.3–3.4]; p<0.005) and low birth weight (OR [95% CI]: 1.7 [1.0–2.9]; p<0.05), but decreased odds of abortion (OR [95% CI]: 0.5 [0.3–0.9]; p<0.05). Reported NSAID use was associated with increased odds of abortion (OR [95% CI]: 2.2 [1.2–4.0]; p<0.05), as was methotrexate/leflunomide use (OR [95% CI]: 3.2 [1.7–6.2]; p<0.0005). Maternal infections were associated with increased odds of preterm birth (OR [95% CI]: 1.9 (1.1–3.5; p<0.05). Finally, there was an association between a diagnosis of Crohn’s disease and odds of abortion (OR [95% CI]: 2.5 [1.5–4.1]; p=0.0005), and between rheumatoid arthritis and low birth weight (OR [95% CI]: 1.9 [1.1–3.3]; p<0.05).

Conclusion:

This prospective analysis, including more than 1,000 pregnancies with CZP exposure in at least the first trimester, represents one of the largest cohorts of pregnancies with known outcomes in patients with CID. Our data confirm the impact of specific CID, concomitant drugs or comorbidities on pregnancy outcomes. In particular, additional use of corticosteroids was highlighted as a risk factor for preterm birth and low birth weight in our cohort of CZP-treated patients. No increase in adverse pregnancy outcomes or specific congenital malformations was observed in CZP-exposed pregnancies, compared to the general population,3,4 which offers further reassurance for women of childbearing age considering CZP treatment.

References:

[1]Sammaritano LR. Arthritis Rheum 2020;72:529–56;

[2]Mariette X. Ann Rheum Dis 2018;77:228–33;

[3]Ventura SJ. Natl Vital Stat Rep 2012;60:1–21;

[4]Lee H. BMC Pregnancy Childbirth 2020;20:33.

Acknowledgements:

This study was funded by UCB Pharma. Editorial services were provided by Costello Medical.

Disclosure of Interests:

Megan Clowse Consultant of: UCB Pharma, Grant/research support from: Janssen, Pfizer, Rebecca Fischer-Betz Consultant of: AbbVie, BMS, Celgene, Chugai, Eli Lilly, Janssen, Novartis, Pfizer, Sanofi, UCB Pharma, Catherine Nelson-Piercy Consultant of: Alliance Pharma, UCB Pharma, Angela Scheuerle Consultant of: Antiretroviral Pregnancy Registry, Harmony Biosciences, IQVIA, ICON, NovoNordisk, PPD, Roche, Sanofi-Genzyme, Syneos, UCB Pharma, ViiV, Thomas Kumke Shareholder of: UCB Pharma, Employee of: UCB Pharma, Bernard Lauwerys Employee of: UCB Pharma, Rachna Kasliwal Employee of: UCB Pharma, Frauke Förger Speakers bureau: Mepha, Roche, UCB Pharma, Grant/research support from: UCB Pharma.

Echocardiography in Minimally Invasive Direct Coronary Artery Bypass

Minimally invasive direct coronary artery bypass (MIDCAB) is a recently developed, less-invasive alternative to standard bypass surgery. MIDCAB is performed through a small incision (2-3 inches) on the beating heart without the use of cardiopulmonary bypass or cardioplegia. It is associated with less trauma and a shorter hospital stay than conventional surgery. Transesophageal echocardiography helps in patient selection by detecting protruding aortic atheromas (PATHs), which are associated with a high risk of stroke during typical cardiopulmonary bypass. MIDCAB may be the technique of choice in patients with PATHs. Intraoperative echocardiography can detect wall motion abnormalities and helps in determining intraoperative myocardial ischemia and the postoperative prognosis. Duplex study of the internal mammary arteries is helpful in evaluating coronary anastomosis patency. Characteristically, a patent coronary anastomosis demonstrates a high diastolic flow fraction, with a ratio between peak diastolic and peak systolic flow velocity of > 1.

Sequential external counterpulsation increases cerebral and renal blood flow

The purpose of this study was to evaluate the effect of sequential external counterpulsation (SECP) on cerebral and renal blood flow. The effect of SECP on carotid and renal artery blood flow was studied in 35 and 18 patients, respectively. With a portable unit, cuffs were applied to the calves and thighs, sequentially inflated with air at the onset of diastole, and deflated at the onset of systole. Carotid and renal artery Duplex studies were performed during intermittent SECP. Flow velocity and flow velocity integral were measured at baseline and during SECP. Diastolic augmentation of carotid and renal artery flow velocity was observed in all patients. The mean carotid flow velocity integral increased by 22% from 27.7 +/- 1.8 cm to 33.1 +/- 2.3 cm (P = 0.001). The mean renal artery flow velocity integral increased by 19% from 21 +/- 1 cm to 25 +/- 1 cm (P = 0.0001). With SECP, a new diastolic Doppler flow velocity wave was observed, with an average peak carotid diastolic flow velocity of 56 +/- 4 cm/sec and an average peak renal artery diastolic flow velocity of 40 +/- 2.5 cm/sec. This diastolic wave was 75% (carotid) and 68% (renal) as high as the systolic wave during SECP. In addition, with SECP the systolic wave increased by 6% and 8% in the carotid and renal artery, respectively (P = 0.02 and 0.006, respectively). In conclusion, SECP significantly increases carotid and renal blood flow. This noninvasive, harmless treatment may be useful to support patients with decreased cerebral and renal perfusion.

High-dose 90Y Mx-diethylenetriaminepentaacetic acid (DTPA)-BrE-3 and autologous hematopoietic stem cell support (AHSCS) for the treatment of advanced breast cancer: a phase I trial

This Phase I trial explores the use of high-dose 90Y conjugated to the antibreast cancer monoclonal antibody BrE-3 and autologous hematologic cell support in the treatment of women with stage four breast cancer. Nine women with heavily pretreated disease were enrolled. All of the patients had BrE-3-positive tumors by immunostaining and were treated with increasing doses of 90Y (15 mCi/m2, 3 patients), 20 mCi/M2 (six patients), and a fixed (50 mg) dose of BrE-3. 111In-labeled BrE-3 (5 mCi) was given simultaneously for scanning purposes. The only toxicity noted was hematological. Grade 4 platelet toxicity requiring transfusion support occurred in four patients. Grade 4 WBC toxicity was seen in two patients that resolved in 3-9 days. All hematological nadirs occurred approximately 25 days after treatment. Objective partial responses were noted in 4 of 8 (50%) patients with measurable tumors. Dose escalation is ongoing.

Synthesis, antitumor activity, and chemical properties of silaplatin and related platinum (II) and platinum (IV) complexes derived from beta-silyl amines

Platinum (II) and platinum (IV) coordination complexes derived from beta-silyl-substituted amines were prepared. The solubility of selected complexes in water and physiological saline was measured, and the effect of the beta-silicon on the reactivity of the complex in aqueous solution was determined by HPLC. The stabilities of selected silyl complexes were compared to the carbon analogues. The cyclic complexes 2a ("silaplatin") and its Pt(IV) analogue, 2b, were very active against L1210 leukemia in vivo. Both the platinum (II) complex 2a and the platinum (IV) complex 2b produced a significant number of cures over the dose range 10-40 mg/kg. The platinum (II) complex 2a, silaplatin, was very active in vivo against an L1210 leukemia subline that was resistant to cisplatin; 2a was also active, when given ip, against ic implanted L1210. The cyclobutanedicarboxylic acid complex 3c was synthesized; this complex was active against both cisplatin sensitive and resistant L1210 leukemia but was less potent than the analogous dichloro compound 2a. The acyclic platinum (II) and platinum (IV) complexes 1a,b were synthesized and unexpectedly found to be inactive in vivo against L1210 leukemia. More lipophilic silaplatin analogues were prepared--Pt(II) complex 2c and Pt(IV) complex 2d have one additional methylene carbon compared to 2a,b, whereas Pt(II) complex 2e and Pt(IV) complex 2f have two additional methylene carbons. Cyclization of the alkyl groups attached to the silicon gave the spiro bicyclic Pt(II) complexes 10a and 11a and the Pt(IV) complexes 10b and 11b.

Clinical and coronary arteriographic features and outcome of recent onset unstable angina

Fifty consecutive patients (43 male and seven female; mean age 51.8 years) with recent onset angina (24.6% of all admissions for unstable angina during a 1-year period) underwent coronary arteriography. Most patients (96.8%) presented with severe angina (Canadian Cardiovascular Society Class III-IV) with admission ECG changes of myocardial ischemia in 46%. Echocardiography (within 2 days of admission) showed normal left ventricular function (LVEF > 50%) in 80% and mild or moderate impairment (LVEF 35-49%) in 12% of patients. Segmental wall motion abnormalities were noted in a small number (12.9%). Coronary angiography revealed significant (> or = 70% diameter stenosis) disease in one vessel in 14 (28%), in two vessels in seven (14%), three vessels in 22 (44%) and no disease in seven (14%) patients. Significant left main stenosis (> or = 50% diameter stenosis) was present in two (5%) patients. Left anterior descending artery was more commonly involved (66%) as compared to the other arteries. A significantly higher incidence of multivessel disease was observed in patients with diabetes mellitus (P < 0.003) and in smokers (P < 0.04). Multiple coronary artery involvement was more common in patients with three or more risk factors for coronary artery disease (P < 0.005). In-hospital non fatal myocardial infarction occurred in three (6%) patients. During follow-up (average 13 +/- 1.28 months) 30 (60%) patients underwent coronary artery bypass surgery, 13 (26%) required coronary angioplasty while seven (14%) were managed by drugs alone with no further mortality and significant symptomatic relief. Patients with recent onset angina, in our setting, frequently have severe multiple vessel coronary artery disease.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of variations in the duration of diffusible-tracer infusions on calculated values of global and local cerebral blood flow

Using dual tracer quantitative digital autoradiography and iodoantipyrine (IAP), we compared local cerebral blood flow (LCBF) measurements using two different infusion times within the same animal. Rats were given concurrent infusions of 14C-IAP and 123I-IAP; one tracer was administered over 20 seconds and the other over 40 seconds. Pairs of autoradiograms, one representing predominantly 123I and the other 14C, were then produced from 20 micron-thick brain sections and images from each section were digitized and processed to produce pairs of digital images of LCBF. The corresponding LCBF images were compared quantitatively on a pixel-by-pixel basis. Global LCBF values were greater (28%) at 20 seconds compared to 40 seconds, consistent with the previously reported "falling flow" phenomenon. Perhaps more importantly, the actual pattern of LCBF differed in certain regions such as the cortex, hippocampus, thalamus, and cerebellum between the two time points. In other words, the quantitative patterns of calculated LCBF values were dependent upon the duration of tracer infusion, even when the infusion times were kept below recommended limits (45 seconds). Thus, errors in LCBF measurements may occur in certain structures even in brief experiments. Because these errors are spatially dependent rather than blood flow dependent, there is presently no model which can be globally applied to the brain to correct them.

A pharmacokinetic model describing the removal of circulating radiolabeled antibody by extracorporeal immunoadsorption

Extracorporeal immunoadsorption is a new technique for removal of circulating radiolabeled antibody from the peripheral blood (1) to reduce background activity for improved tumor imaging, and (2) to reduce whole-body and marrow toxicity when high doses of radiolabeled antibodies are used for antitumor therapy. A pharmacokinetic model was developed to describe plasma disappearance of 111In-KC-4G3 prior to, during, and after immunoadsorption in humans. The model is developed based on a two-compartment open model, and during immunoadsorption a third compartment is added for removed radioactivity by the immunoadsorption column. Goodness-of-fit statistics indicate a good fit of the model to the data. The resulting pharmacokinetic parameters for a selected patient are V1 = 2.64 L, VSS = 3.64 L, t 1/2 alpha = 3.77 hr, and t 1/2 beta = 48.5 hr. The immunoadsorption clearance (CLIA = 19.3 ml/min) was 21-fold greater than the patient's plasma clearance (CL10 = 0.899 ml/min), indicating a very effective immunoadsorption process. The model predicts an increase in plasma radioactivity upon termination of immunoadsorption, probably due to redistribution of radioactivity from the extravascular compartment to the plasma in response to the rapid decline in plasma radioactivity during immunoadsorption. Two series of simulations were performed to examine the influence of onset time and duration of immunoadsorption. In series one the onset time was varied and in series two immunoadsorption duration was varied. In series one, the predicted radioactivity amounts adsorbed by the immunoadsorption column ranged from 75% of the injected dose (4-hr onset) to 52% of the injected dose (24-hr onset). In series two, immunoadsorbed radioactivity ranged from 32% (2-hr duration) to 64% of the injected dose (12-hr duration). When instituted as early as 4 hr, the predictions suggest that earlier immunoadsorption onset improves the effectiveness of radioactivity removal, relating to higher early circulation concentrations, and longer immunoadsorption periods remove more radioactivity, but also result in larger predicted radioactivity redistribution form tissue to plasma. To employ the immunoadsorption procedure for tumor imaging and therapy optimally, the data and our predictions indicate that a compromise must be made that will balance immunoadsorption onset and duration against tumor radioactivity uptake and subsequent radioactivity redistribution from tissues back to plasma. Together with biologic considerations providing sufficient antigen-antibody interaction and dependent on the utilized radioisotope, these data support the utility of extracorporeal immunoadsorption during the radioimmunodetection of cancer and for future therapeutic applications.

Imaging of non-small cell lung cancers with a monoclonal antibody, KC-4G3, which recognizes a human milk fat globule antigen

To determine the role of lung cancer tumor imaging with monoclonal antibodies directed against high molecular weight human milk fat globule antigens, we administered i.v. 111In-KC-4G3 to 24 patients with advanced non-small cell lung cancer. One mg of 111In-KC-4G3 was mixed with 0, 9, 49, 99, or 499 mg of unlabeled KC-4G3 and infused i.v. over 1 to 5 h. The mean 111In-KC-4G3 radiochemical purity was greater than 97% and the resultant immunoreactivity averaged 62%. Successful imaging of cancer sites was accomplished in 92% of 24 patients, and 57% of 91 total lesions were visualized. Successful localization of tumor sites related to size (P less than 0.001), with 81% of lesions greater than 3.0 cm in diameter, 50% of lesions 1.5 to 3 cm, and 6% of lesions less than 1.5 cm successfully imaging, and to location (P less than 0.05), with 69% of pulmonary lesions, 80% of soft tissue lesions, and only 32% of bone metastases being visualized. Nonspecific reticulo-endothelial uptake of radioactivity was a major problem. Approximately 35% of 111In was chelated to serum transferrin by 24 and 48 h after infusion. The mean t 1/2 beta for plasma radioisotope and immunoreactive KC-4G3 was 29 and 27 h, respectively. There was no correlation between total infused antibody dose and imaging success or between total dose and effect on 111In and KC-4G3 kinetics. Circulating free KC-4 antigen was measurable in all but one patient before study. Tumor biopsy following infusion could demonstrate antibody presence but not saturable antigen binding. We conclude that (a) 111In-KC-4G3 demonstrates successful tumor localization in non-small cell lung cancers bearing generally high expression of its antigen and (b) further investigations to diminish nonspecific radioactivity for imaging and utilization of high dose radiolabeled antibody for therapeutic intent are warranted.

Pharmacokinetics, biodistribution, and gamma camera imaging of 111In-KC-4G3 murine monoclonal antibody in athymic nude mice with or without human tumor xenografts

The pharmacokinetics and tissue distribution of the monoclonal antibody radioconjugate 111In-diethylenetriaminepentaacetic acid-KC-4G3, which is directed against a high molecular weight mucin(s) antigen expressed on the human milk fat globule and many epithelial cell membranes, were examined in BALB/c nude mice with and without xenografts of the human tumor lines ZR-75 (mammary adenocarcinoma, KC-4G3 antigen positive) and BALL-1 (B-cell lymphoma, KC-4G3 antigen negative). Plasma of ZR-75 and BALL-1 tumor-bearing nude mice inoculated with 111In-KC-4G3 had a higher initial volume of distribution (V1), steady state volume of distribution (Vss), and plasma clearance and a lower initial half-life (t1/2 alpha) than non-tumor-bearing nude mice. There were no significant differences in biological half-life (t1/2 beta) in tumor- and non-tumor-bearing nude mice. Urinary and fecal excretion of radioactivity by ZR-75 tumor-bearing mice was greater than that of BALL-1 and non-tumor-bearing mice. Localization of 111In-KC-4G3 in mice bearing xenografts of ZR-75 was significantly greater than in mice with BALL-1 tumors. Uptake of 111In-KC-4G3 by ZR-75 tumors averaged 14% of injected dose/g at 72 h after inoculation and was unaffected by antibody dose. Significantly, the radioconjugate concentration in ZR-75 tumors remained relatively constant from 72 to 336 h post-inoculation, while that in normal tissues declined considerably over this period. Nonspecific reticuloendothelial tissue uptake of 111In-KC-4G3 was only moderately affected by pretreatment with a large excess of unlabeled normal mouse immunoglobulin and was not changed by treatment with asialofetuin. Further enhancement of specific localization of 111In-KC-4G3 was obtained by subtraction of the blood pool identified by co-inoculation of 131I-labeled, isotype-identical, normal mouse immunoglobulin. Gamma camera images of 111In-KC-4G3-inoculated ZR-75 tumor-bearing mice showed enhanced tumor localization compared to mice with BALL-1 tumors. The results of this study suggest that 111In-KC-4G3 may prove useful for imaging and possibly therapy of human malignancies expressing the high molecular weight epithelial mucin(s).

Mapping regional cerebral vascular transit time by simultaneous determination of local cerebral blood flow and local cerebral blood volume

We developed a method for autoradiographic mapping of regional cerebral transit time (CTT) by simultaneously measuring local cerebral blood flow (LCBF) and local cerebral blood volume (LCBV). Previously described single-tracer techniques for determination of LCBF and LCBV were modified for dual-tracer, 99mTc and 14C, autoradiography and used to create digital images of LCBF and LCBV from the same brain sections in a series of normal rats. The images were aligned and ratio images (LCBV/LCBF) were then generated which reflected CTT. Regional cerebral transit time was found to vary significantly through-out the brain in a pattern only partially related to that of blood flow. Such CTT heterogeneity could cause errors in implementation of kinetic models which assume uniform or monovariant distributions of vascular transit time.

In vitro and in vivo evaluation of [123I]IBZM: a potential CNS D-2 dopamine receptor imaging agent

In vitro binding characteristics of a CNS dopamine D-2 receptor imaging agent, (S)-N-[(1-ethyl-2-pyrrolidinyl)] methyl-2-hydroxy-3-iodo-6-methoxybenzamide [( 125I]IBZM), was carried out in rats. Also brain images, as well as organ biodistribution were determined in a monkey following the administration of 123I-labeled compound. The S-(-)-I[125I]IBZM showed high specific dopamine D-2 receptor binding in rat striatum (Kd = 0.426 +/- 0.082 nM, Bmax = 480 +/- 22 fmol/mg of protein). Competition of various ligands for the IBZM binding displayed the following rank order of potency: spiperone greater than S(-)IBZM much greater than R(+)IBZM greater than or equal to S(-)BZM greater than dopamine greater than ketanserin greater than SCH-23390 much greater than propranolol, norepinephrine, serotonin. In vivo planar images of a monkey injected with [123I]IBZM demonstrated a high concentration in basal ganglia of brain. The ratios of activity in the basal ganglia to cerebellum and the cortex to cerebellum in monkey brain were 4.93 and 1.44, respectively, at 120 min postinjection. These preliminary results indicate that [123I]IBZM is a potentially promising imaging agent for the investigation of dopamine D-2 receptors in humans.

Dopamine D-2 receptor imaging radiopharmaceuticals: synthesis, radiolabeling, and in vitro binding of (R)-(+)- and (S)-(-)-3-iodo-2-hydroxy-6-methoxy-N- [(1-ethyl-2-pyrrolidinyl)methyl]benzamide

In developing central nervous system (CNS) dopamine D-2 receptor imaging agents, enantiomers, R-(+) and S-(-) isomers, of 3-[125I]iodo-2-hydroxy-6-methoxy-N-[(1-ethyl-2- pyrrolidinyl)methyl]benzamide, [125I]IBZM, were synthesized, and their in vitro binding characteristics were evaluated in rat striatum tissue preparation. The (S)-(-)-[125I]IBZM showed high specific dopamine D-2 receptor binding (Kd = 0.43 nM, Bmax = 0.48 pmol/mg of protein). Competition data of various ligands for IBZM binding displayed the following rank order of potency: spiperone greater than (S)-(-)-IBZM greater than (+)-butaclamol much greater than (R)-(+)-IBZM greater than (S)-(-)-BZM greater than dopamine greater than ketanserin greater than SCH23390 much greater than propanolol. The results indicate that [125I]IBZM binds specifically to the dopamine D-2-receptor with stereospecificity. The [123I]IBZM is potentially useful as an imaging agent for the investigation of dopamine D-2 receptors in humans.

The toxicity and mutagenicity of S-3-iodo-N-(1-ethyl-2-pyrrolidinyl)methyl-2-hydroxy-6-methoxybenzamide (IBZM), a new CNS D-2 dopamine receptor imaging agent

IBZM is one of several benzamide derivatives showing a high affinity for the CNS D-2 dopamine receptor. Carrier-free [123I]IBZM is potentially useful as a nuclear medicine imaging agent for investigating CNS D-2 dopamine receptor in humans. This study describes the acute toxicity of IBZM in the rat and rabbit, its subchronic toxicity in the rabbit and its mutagenicity measured by the Ames test. IBZM had a 24 hour LD50 of 400 mg/kg in the rat and 50 mg/kg in the rabbit when administered i.v. Deaths occurred within minutes of dosing. Some necrosis was evident at the injection site in IBZM treated animals which was not found in the controls. No gross or histological differences between experimental animals and controls were evident in surviving animals when necropsied 14 days after dosing. Repeated exposure of rabbits to IBZM at a total cumulative dose of 100,000 times the expected clinical dose revealed no consistent changes in hematology, blood chemistry, blood enzymes or tissue pathology. IBZM was not mutagenic in the modified Ames assay with or without metabolic activation in the TA98 and TA100 tester strains. It is therefore unlikely that acute adverse effects will be associated with the diagnostic use of this drug in man.